Contents

Preface to Sixth Edition

Preface to the First Edition

vii

Acknowledgments

Chapter 1

Introduction and Reader’s Guide

Including Rationale for Labels and Abbreviations

Chapter 2

External Morphology of the Central Nervous System

The Spinal Cord: Gross Views and Vasculature

The Brain: Lobes, Principle Brodmann Areas, Sensory-Motor Somatotopy

The Brain: Gross Views, Vasculature, and MRI

The Cranial Nerves in MRI

The Insula: Gross View and MRI

The Meninges, Cisterns, and Meningeal and Cisternal Hemorrhages

The Ventricles and Ventricular Hemorrhages

Chapter 3

Dissections of the Central Nervous System

Lateral, Medial, and Ventral Aspects

Overall Views

Chapter 4

Internal Morphology of the Brain in Slices and MRI

Brain Slices in the Coronal Plane Correlated with MRI

Brain Slices in the Axial Plane Correlated with MRI

Chapter 5

Internal Morphology of the Spinal Cord and Brain in Stained Sections

The Spinal Cord with CT and MRI

Arterial Patterns Within the Spinal Cord With Vascular Syndromes

The Degenerated Corticospinal Tract

The Medulla Oblongata with MRI and CT

Arterial Patterns Within the Medulla Oblongata With Vascular Syndromes

110

The Cerebellar Nuclei

112

The Pons with MRI and CT

116

Arterial Patterns Within the Pons With Vascular Syndromes

124

The Midbrain with MRI and CT

126

Arterial Patterns Within the Midbrain With Vascular Syndromes

136

The Diencephalon and Basal Nuclei with MRI

138

Arterial Patterns Within the Forebrain With Vascular Syndromes

158

Chapter 6

Internal Morphology of the Brain in Stained Sections:

Axial-Sagittal Correlations with MRI

161

Axial-Sagittal Correlations

162

Chapter 7

Synopsis of Functional Components, Tracts, Pathways, and Systems

173

Components of Cranial and Spinal Nerves

174

Orientation

176

Sensory Pathways

178

Motor Pathways

190

Cerebellum and Basal Nuclei

204

Optic, Auditory, and Vestibular Systems

220

Limbic System

232

Preface to the Sixth Edition

revious editions of Neuroanatomy have endeavored 1) to provide a

drawing and its companion stained section in the anatomical orienta-

structural basis for understanding the function of the central ner-

tion. At the same time, it introduces, on the same set of pages, the im-

vous system; 2) to emphasize points of clinical relevance through use

portant concept that CNS anatomy, both external and internal, is ori-

of appropriate terminology and examples; and 3) to integrate neuro-

ented differently in MRI or CT. It is the clinical orientation issue that

anatomical and clinical information in a format that will meet the edu-

will confront the student/clinician in the clinical setting. It is certainly

cational needs of the user. The goal of the sixth edition is to continue

appropriate to introduce, and even stress, this view of the brain and

this philosophy and to present structural information and concepts in

spinal cord in the basic science years.

an even more clinically useful and relevant format. Information learned

Third, new images have been included in chapter 8. These include,

in the basic science setting should flow as seamlessly as possible into the

but are not limited to, new examples of general vessel arrangement in

clinical setting.

MRA, examples of specific vessels in MRI, and some additional exam-

I have received many constructive suggestions and comments from

ples of hemorrhage.

my colleagues and students. This is especially the case for the modifi-

Fourth, additional examples of cranial nerves traversing the sub-

cations made in Chapters 2, 5, 7, 8, and 9 in this new edition. The

arachnoid space are included. In fact, the number of MRI showing cra-

names of the individuals who have provided suggestions or comments

nial nerves has been doubled. In addition, each new plate starts with a

are given in the Acknowledgments. This thoughtful and helpful input

gross anatomical view of the nerve (or nerves) shown in the succeed-

is greatly appreciated and has influenced the preparation of this new

ing MRI in that figure.

edition.

Fifth, additional clinical information and correlations have been in-

The major changes made in the sixth edition of Neuroanatomy are as

cluded. These are in the form of new images, new and/or modified fig-

follows:

ure descriptions, and changes in other portions of the textual elements.

First, recognizing that brain anatomy is seen in clear and elegant de-

Sixth, in some instances, existing figures have been relocated to im-

tail in MRI and CT, and that this is the primary way the brain is viewed

prove their correlation with other images. In other instances, existing

in the health care setting, additional new images have been incorporated

figures have been repeated and correlated with newly added MRI or

into this new edition. Every effort has been made to correlate the MRI

CT so as to more clearly illustrate an anatomical-clinical correlation.

or CT with brain or spinal cord anatomy by relating these images on the

Seventh, a new chapter (chapter 9), consisting of approximately 240

same page or on facing pages. New MRI or CT have been introduced

study and review questions and answers in the USMLE style, has been

into chapter 2 (spinal cord, meningeal hemorrhages correlated with the

added. All of these questions have explained answers keyed to specific

meninges, cisterns, hemorrhage into the brain, hemorrhage into the

pages in the Atlas. Although not designed to be an exhaustive set, this

ventricles correlated with the structure of the ventricles), chapter 5

new chapter should give the user of this atlas a unique opportunity for

(spinal cord and brainstem), and chapter 8 (vascular).

self-assessment.

Second, the structure of the central nervous system should be avail-

Two further issues figured prominently in the development of this

able to the student (or the medical professional for that matter) in a for-

new edition. First, the question of whether to use eponyms in their

mat that makes this information immediately accessible, and applica-

possessive form. To paraphrase one of my clinical colleagues “Parkin-

ble, to the requirements of the clinical experience. It is commonplace

son did not die of his disease (Parkinson disease), he died of a stroke;

to present brain structure in an anatomical orientation (e.g., the colli-

it was never his own personal disease.” There are rare exceptions, such

culi are “up” in the image and the interpeduncular fossa is “down”).

as Lou Gehrig’s disease, but the point is well taken. McKusick

However, when the midbrain is viewed in an axial MRI or CT, the re-

(1998a,b) has also made compelling arguments in support of using the

verse is true: the colliculi are “down” in the image and the interpedun-

non-possessive form of eponyms. It is, however, acknowledged that

cular fossa is “up”. There are many good reasons for making brainstem

views differ on this question—much like debating how many angels

images available in an anatomical orientation and for teaching this view

can dance on the head of a pin. Consultation with my neurology and

in the academic setting. These reasons are recognized in this book. On

neurosurgery colleagues, a review of some of the more comprehensive

the other hand, the extensive use of MRI or CT in all areas of medi-

neurology texts (e.g., Rowland, 2000; Victor and Ropper, 2001), and

cine, not just the clinical neurosciences, requires that students be

the standards established in The Council of Biology Editors Manual for

clearly aware of how brain and spinal cord structure is viewed, and used, in

Authors, Editors, and Publishers (1994) and the American Medical As-

the clinical environment. To address this important question, a series of

sociation’s Manual of Style (1998) clearly indicate an overwhelming

illustrations, including MRI or CT, are introduced in the spinal cord

preference for the non possessive form. Recognizing that many users

and brainstem sections of chapter 5. These images are arranged to show

of this book will enter clinical training, it was deemed appropriate to

1) the small colorized version of the spinal cord or brainstem in an

encourage a contemporary approach. Consequently, the non posses-

anatomical orientation; 2) the same image flipped bottom-to-top into

sive form of the eponym is used.

a clinical orientation; and 3) the clinical orientation of the colorized

The second issue concerns use of the most up-to-date anatomical

line drawing followed by T1 and T2 MRI and/or CT at levels compa-

terminology. With the publication of Terminologia Anatomica (Thieme,

rable to the line drawing and corresponding stained section. This ap-

New York, 1998), a new official international list of anatomical terms

proach retains the inherent strengths of the full-page, colorized line

for neuroanatomy is available. This new publication, having been

vi Preface to the Sixth Edition

adopted by the International Federation of Associations of Anatomists,

References:

supersedes all previous terminology lists. Every effort has been made

Council of Biology Editions Style Manual Committee. Scientific Style and

to incorporate any applicable new or modified terms into this book.

Format—The CBE Manual for Authors, Editors, and Publishers. 6^th Ed.

The number of changes is modest and related primarily to directional

Cambridge: Cambridge University Press, 1994.

terms: posterior for dorsal, anterior for ventral, etc. In most cases, the

Federative Committee on Anatomical Terminology. Terminologia Ana-

previous term appears in parentheses following the official term, i.e.,

tomica. Thieme, Stuttgart and New York, 1998.

posterior (dorsal) cochlear nucleus. It is almost certain that some changes

Iverson, MA et al. American Medical Association Manual of Style—A Guide

have eluded detection; these will be caught in subsequent printings.

for Authors and Editors. 9^th Ed. Baltimore: Williams & Wilkins, 1998.

Last, but certainly not least, the sixth edition is a few pages

McKusick, VA. On the naming of clinical disorders, with particular ref-

longer than was the fifth edition. This results exclusively from the

erence to eponyms. Medicine 1998;77: 1-2.

inclusion of more MRI and CT, a better integration of anatomical-

McKusick, VA. Mendelian Inheritance in Man, A Catalog of Human Genes

clinical information, including more clinical examples (text and il-

and Genetic Disorders. 12^th Ed. Baltimore: The Johns Hopkins Uni-

lustrations), and the inclusion of Study/Review and USMLE style

versity Press, 1998.

questions with explained answers.

Rowland, LP. Merritt’s Neurology. 10^th Ed. Baltimore: Lippincott Williams

& Wilkins, 2000.

Duane E. Haines

Victor, M and Ropper, AH. Adams and Victor’s Principles of Neurology. 7^th

Jackson, Mississippi

Ed. New York: McGraw-Hill, Medical Publishing Division, 2001.

Preface to the First Edition

his atlas is a reflection of, and a response to, suggestions from pro-

dents in the laboratory and greatly enhances their ability to grasp and

fessional and graduate students over the years I have taught human

retain information on CNS connections. While this atlas does not at-

neurobiology. Admittedly, some personal philosophy, as regards

tempt to teach clinical concepts, a chapter correlating selected views

teaching, has crept into all parts of the work.

of angiograms and CT scans with morphological relationships of cere-

The goal of this atlas is to provide a maximal amount of useful in-

bral arteries and internal brain structures is included. These examples

formation, in the form of photographs and drawings, so that the initial

illustrate that a clear understanding of normal morphological relation-

learning experience will be pleasant, logical, and fruitful, and the re-

ships, as seen in the laboratory, can be directly transposed to clinical

view process effective and beneficial to longterm professional goals. To

situations.

this end several guiding principles have been followed. First, the entire

This atlas was not conceived with a particular audience in mind. It

anatomy of the central nervous system (CNS), external and internal,

was designed to impart a clear and comprehensive understanding of

has been covered in appropriate detail. Second, a conscientious effort

CNS morphology to its readers, whoever they may be. It is most obvi-

has been made to generate photographs and drawings of the highest

ously appropriate for human neurobiology courses as taught to med-

quality: illustrations that clearly relay information to the reader. Third,

ical, dental, and graduate students. In addition, students in nursing,

complementary information always appears on facing page. This may

physical therapy, and other allied health curricula, and psychology as

take the form of two views of related structures such as brainstem or

well, may also find its contents helpful and applicable to their needs.

successive brain slices or a list of abbreviations and description for a

Inclusion and integration of blood vessel patterns, both external and in-

full-page figure. Fourth, illustrations of blood supply have been in-

ternal, and the summary pathway drawings may be useful to the indi-

cluded and integrated into their appropriate chapters. When gross

vidual requiring a succinct, yet comprehensive review before taking

anatomy of the brain is shown, the patterns of blood vessels and rela-

board exams in the neurological, neurosurgical, and psychiatric spe-

tionships of sinuses appear on facing pages. The distribution pattern of

cialties.

blood vessels to internal CNS structures is correlated with internal

The details in some portions of this atlas may exceed that found in

morphology as seen in stained sections. Including information on ex-

comparable parts of other atlases. If one is to err, it seems more judi-

ternal vascular patterns represents a distinct departure from what is

cious to err on the side of greater detail than on the side of inadequate

available in most atlases, and illustrations of internal vessel distribution

detail. If the student is confronted with more information on a partic-

are unique to this atlas.

ular point than is needed during the initial learning process, he or she

There are other features which, although not unique in themselves,

can simply bypass the extra information. However, once the initial

do not usually appear in atlas format. In the chapter containing cross-

learning is completed, the additional information will be there to en-

sections, special effort has been made to provide figures that are accu-

hance the review process. If students have inadequate information in

rate, clear, and allow considerable flexibility in how they can be used

front of them it may be difficult, or even impossible, to fill in missing

for both teaching and learning. The use of illustrations that are one-half

points that may not be part of their repertoire of knowledge. In addi-

photograph and one-half drawing is not entirely novel. In this atlas,

tion, information may be inserted out of context, and, thereby, hinder

however, the sections are large, clearly labeled, and the drawing side

the learning experience.

is a mirror-image of the photograph side. One section of the atlas is de-

A work such as this is bound to be subject to oversights, and for such

voted to summaries of a variety of major pathways. Including this ma-

foibles, I am solely responsible. I welcome comments, suggestions, and

terial in a laboratory atlas represents a distinct departure from the stan-

corrections from my colleagues and from students.

dard approach. However, feedback over the years strongly indicates

that this type of information in atlas format is extremely helpful to stu-

Duane E. Haines

vii

Acknowledgments

s was the case in previous editions of this book, my colleagues and

A. Rosenquist, M. Schwartz, J. Scott, V. Seybold, D. Smith, S. Sten-

students in both medical and graduate programs have been most

saas, D. Tolbert, F. Walberg, S. Walkley, M. Woodruff, M. Wyss,

gracious in offering their suggestions and comments. I greatly appreci-

and B. Yezierski. The stained sections used in this atlas are from the

ate their time and interest in the continuing usefulness of this book.

teaching collection in the Department of Anatomy at West Virginia

As changes were being contemplated for this new edition, input on

University School of Medicine.

potential modifications was solicited from faculty as well as students in

Dr. R. Brent Harrison (former Chairman of Radiology, UMMC),

an effort to ascertain how these changes might impact on the usefulness

Dr. Robert D. Halpert (current Chairman of Radiology, UMMC) and

of this Atlas. These individuals went out of their way to review the doc-

Dr. Gurmett Dhilon (Neuroradiology) generously continue to give me

uments that were provided and to give insightful, and sometimes

full access to all their facilities. I would like to express a special thanks

lengthy, comments on the pros and cons of the ideas being considered.

to Mr. W. (Eddie) Herrington (Chief CT/MRI Technologist) and Mr.

This input was taken into consideration as the initial plans were modified

Joe Barnes (Senior MRI Technologist) for their outstanding efforts to

and finalized by the author and then incorporated into this new edition.

supply new images and their special efforts to generate images at spe-

The faculty who gave generously of their time and energy were Drs. A.

cific planes for this new edition. In the same vein, Drs. G. Dhilon and

Agmon, C. Anderson, R. Baisden, S. Baldwin, J. L. Culberson, B. Hal-

S. Crawford also made special attempts to get specific MRI at special

las, J. B. Hutchins, T. Imig, G. R. Leichnetz, E. Levine, R. C. S. Lin, J.

planes. I am also deeply appreciative to several technologists and nurses

C. Lynch, T. McGraw-Ferguson, G. F. Martin, G. A. Mihailoff, R. L.

in the CT/MRI suite, and particularly to Master Johnathan Barnes, for

Norman, R. E. Papka, H. J. Ralston, J. Rho, L. T. Robertson, J. D.

being such cooperative “patients” as we worked to generate scans that

Schlag, K. L. Simpson, and C. Stefan. The students who offered helpful

matched stained sections in the Atlas as closely as possible.

and insightful comments were A. Alqueza (medical student, University

Modifications, both great and small, to the artwork and labeling

of Florida at Gainesville), A. S. Bristol (graduate student, University of

scheme, as well as some new renderings, were the work of Mr.

California at Irvine), L. Simmons (medical student, Vanderbilt Univer-

Michael Schenk (Director of Biomedical Illustration Services). Mr. Bill

sity), J. A. Tucker (medical student, The University of Mississippi Med-

Armstrong (Director of Biomedical Photography) produced outstand-

ical Center), S. Thomas (graduate student, University of Maryland at

ing photographs of gross specimens and slices, CTs, MRIs, and MRAs.

College Park), and M. Tomblyn (medical student, Rush Medical Col-

I am very appreciative of the time, effort, and dedication of these indi-

lege). I greatly appreciate their comments and suggestions.

viduals to create the very best artwork and photographs possible for

I would also like to thank my colleagues in the Department of

this new edition. Ms. Katherine Squires did all the typing for the sixth

Anatomy at The University of Mississippi Medical Center (UMMC) for

edition. Her excellent cooperation, patience, and good-natured repar-

their many helpful suggestions and comments. My colleagues in the

tee with the author were key elements in completing the final draft in

Department of Neurosurgery at UMMC (Drs. A. Parent [Chairman],

a timely manner.

L. Harkey, J. Lancon, J. Ross, D. Esposito, and G. Mandybur) and in

This sixth edition would not have been possible without the inter-

the Department of Neurology at UMMC (especially Drs. J. Corbett

est and support of the publisher, Lippincott Williams & Wilkins. I want

[Chairman], S. Subramony, H. Uschmann, and M. Santiago) have of-

to express thanks to my editor, Ms. Betty Sun (Acquisitions Editor), to

fered valuable input on a range of clinical issues. I am especially in-

Mr. Dan Pepper (Associate Managing Editor), to Ms. Erica Lukenich

debted to Dr. J. A. Lancon (Neurosurgery) for his significant contri-

(Editorial Assistant), Ms. Jennifer Weir (Associate Production Man-

butions to this new edition. These include his willingness to participate

ager), and to Mr. Joe Scott (Marketing Manager) for their encourage-

as co-author of Chapter 9 and his careful review of all new clinical in-

ment, continuing interest, and confidence in this project. Their coop-

formation added to the book. I would also like to thank Ms. Amanda

eration has given me the opportunity to make the improvements seen

Ellis, B.S.N., for keeping my friend John on track.

herein.

I am indebted to the following individuals for their careful review

Last, but certainly not least, I would like to express a special thanks

of previous editions of the book: Drs. B. Anderson, R. Borke, Patricia

to my wife, Gretchen. She put up with me while these revisions were

Brown, Paul Brown, T. Castro, B. Chronister, A. Craig, E. Dietrichs,

in progress, carefully reviewed all changes in the text and all ques-

J. Evans, B. Falls, C. Forehand, R. Frederickson, E. Garcis-Rill, G.

tions/answers, and was a tangible factor in getting everything done. I

Grunwald, J. King, A. Lamperti, K. Peusner, C. Phelps, D. Rosene,

dedicate this edition to Gretchen.

Introduction and Reader’s Guide

t a time when increasing numbers of atlases and text-

The present atlas addresses these points. The goal is not

books are becoming available to students and instruc-

only to show external and internal structure per se but also

tors, it is appropriate to briefly outline the approach used in

to demonstrate that the relationship between brain anatomy

this volume. Most books are the result of 1) the philosophic

and MRI/CT, the blood supply to specific areas of the CNS

approach of the author/instructor to the subject matter and

and the arrangement of pathways located therein, the neu-

2) students’ needs as expressed through their suggestions

roactive substances associated with pathways, and examples

and opinions. The present atlas is no exception, and as a re-

of clinical deficits are inseparable components of the learn-

sult, several factors have guided its further development.

ing experience. An effort has been made to provide a for-

These include an appreciation of what enhances learning in

mat that is dynamic and flexible—one that makes the learn-

the laboratory and classroom, the inherent value of corre-

ing experience an interesting and rewarding exercise.

lating structure with function, the clinical value of under-

standing the blood supply to the central nervous system

The relationship between blood vessels and specific brain

(CNS), and the essential importance of integrating anatomy

regions (external and/or internal) is extremely important

with clinical information and examples. The goal is to make

considering that approximately 50% of what goes wrong in-

it obvious to the user that structure and function in the CNS

side the skull, producing neurological deficits, is vascular-

are integrated elements and not separate entities.

related. To emphasize the value of this information, the dis-

Most neuroanatomic atlases approach the study of the

tribution pattern of blood vessels is correlated with external

CNS from fundamentally similar viewpoints. These atlases

spinal cord and brain anatomy (Chapter 2) and with inter-

present brain anatomy followed by illustrations of stained

nal structures such as tracts and nuclei (Chapter 5), re-

sections, in one or more planes. Although variations on this

viewed in each pathway drawing (Chapter 7), and shown in

theme exist, the basic approach is similar. In addition, most

angiograms, MRAs, and MRVs (Chapter 8). This approach

atlases do not make a concerted effort to correlate vascular

has several advantages: 1) the vascular pattern is immediately

patterns with external or internal brain structures. Also,

related to the structures just learned, 2) vascular patterns

most atlases include little or no information on neurotrans-

are shown in the sections of the atlas in which they belong,

mitters and do not integrate clinical examples and informa-

3) the reader cannot proceed from one part of the atlas to

tion with the study of functional systems.

the next without being reminded of blood supply, and 4) the

Understanding CNS structure is the basis for learning path-

conceptual importance of the distribution pattern of blood

ways, neural function, and for developing the skill to diagnose

vessels in the CNS is repeatedly reinforced.

the neurologically impaired patient. Following a brief period

The ability to diagnose a neurologically compromised pa-

devoted to the study of CNS morphology, a significant por-

tient is specifically related to a thorough understanding of

tion of many courses is spent learning functional systems. This

pathway structure, function, blood supply, and the rela-

learning experience may take place in the laboratory because

tionships of this pathway to adjacent structures. To this end

it is here that the student deals with images of representative

Chapter 7 provides a series of semidiagrammatic illustrations

levels of the entire neuraxis. However, few attempts have

of various clinically relevant pathways. Each figure shows 1)

been made to provide the student with a comprehensive and in-

the trajectory of fibers that comprise the entire pathway; 2)

tegrated guide—one that correlates, 1) external brain anatomy

the laterality of fibers comprising the pathway, this being an

with MRI and blood supply; 2) meninges and ventricles with

extremely important concept in diagnosis; 3) the positions

examples of meningeal, ventricular, and brain hemorrhage;

and somatotopy of fibers comprising each pathway at repre-

3) internal brain anatomy with MRI, blood supply, the orga-

sentative levels; 4) a review of the blood supply to the en-

nization of tracts and nuclei and selected clinical examples; 4)

tire pathway; 5) important neurotransmitters associated

summaries of clinically relevant pathways with neurotrans-

with fibers of the pathway; and 6) examples of deficits seen

mitters, numerous clinical correlations, and the essential con-

following lesions of the pathway at various levels through-

cept of laterality; and 5) includes a large variety of images such

out the neuraxis. This chapter is designed to be used by itself

as angiogram, computed tomography (CT), magnetic reso-

or integrated with other sections of the atlas; it is designed to

nance imaging

(MRI), magnetic resonance angiography

provide the reader with the structural and clinical essentials

(MRA), and magnetic resonance venography (MRV).

of a given pathway in a single illustration.

Introduction and Reader’s Guide

The advent and common use of imaging methods (MRI,

The Brain and Related Structures in CT

MRA, and MRV) mandates that such images become an inte-

STRUCTURE/FLUID/SPACE

GREY SCALE

gral part of the educational process when teaching and/or

Bone, acute blood

Very white

learning clinically applicable neuroscience. To this end, this

Enhanced tumor

Very white

book contains about 175 MRI and CT images and 12 MRA and

Subacute blood

Light grey

MRV. All of these images are directly correlated with external

Muscle

Light grey

brain anatomy such as gyri and sulci, internal structures in-

Grey matter

Light grey

cluding pathways and nuclei, cranial nerves and adjacent struc-

White matter

Medium grey

tures, or they demonstrate examples of hemorrhages related

Cerebrospinal fluid

Medium grey to black

to the meninges and ventricles or the parenchyma of the brain.

Air, Fat

Very black

Imaging the Brain (CT and MRI): Imaging the brain in

vivo is now commonplace for the patient with neurological

The advantages of CT are 1) it is rapidly done, which is

deficits that may indicate a compromise of the central nervous

especially important in trauma; 2) it clearly shows acute and

system. Even most rural hospitals have, or have easy access to,

subacute hemorrhages into the meningeal spaces and brain;

CT or MRI. With these facts in mind, it is appropriate to make

3) it shows bone (and skull fractures) to advantage; and 4)

a few general comments on these imaging techniques and what

it is less expensive than MRI. The disadvantages of CT are

is routinely seen, or best seen, in each. For details of the meth-

1) it does not clearly show acute or subacute infarcts or is-

ods and techniques of CT and MRI consult sources such as

chemia, or brain edema; 2) it does not clearly differentiate

Grossman (1996), Lee et al. (1999), or Buxton (2002).

white from grey matter within the brain nearly as well as

Computed Tomography (CT): In CT, the patient is

MRI; and 3) it exposes the patient to ionizing radiation.

passed between a source of x-rays and a series of detectors.

Magnetic Resonance Imaging (MRI): The tissues

Tissue density is measured by the effects of x-rays on atoms

of the body contain proportionately large amounts of pro-

within the tissue as these x-rays pass through the tissue.

tons (hydrogen). Protons have a positive nucleus, a shell of

Atoms of higher number have a greater ability to attenuate

negative electrons, and a north and south pole; they func-

(stop) x-rays while those with lower numbers are less able to

tion like tiny spinning bar magnets. Normally, these atoms

attenuate x-rays. The various attenuation intensities are

are arranged randomly in relation to each other due to the

computerized into numbers (Hounsfield units or CT num-

constantly changing magnetic field produced by the elec-

bers). Bone is given the value of +1,000 and is white, while

trons. MRI uses this characteristic of protons to generate

air is given a value of

1,000 and is black. Extravascular

images of the brain and body.

blood, an enhanced tumor, fat, the brain (grey and white

When radio waves are sent in short bursts into the mag-

matter), and cerebrospinal fluid form an intervening contin-

net containing the patient, they are called a radiofrequency

uum from white to black. A CT image of a patient with sub-

pulse (RP). This pulse may vary in strength. When the fre-

arachnoid hemorrhage illustrates the various shades seen in a

quency of the RP matches the frequency of the spinning pro-

CT (Fig. 1-1). In general, the following table summarizes the

ton, the proton will absorb energy from the radio wave (res-

white to black intensities seen for selected tissues in CT.

onance). The effect is two-fold. First, the magnetic effects

of some protons are cancelled out and second, the magnetic

effects and energy levels in others are increased. When the

RP is turned off, the relaxed protons release energy (an

“echo”) that is received by a coil and computed into an im-

age of that part of the body.

The two major types of MRI images (MRI/T1 and

MRI/T2) are related to the effect of RP on protons and the

reactions of these protons (relaxation) when the RP is

turned off. In general, those cancelled out protons return

slowly to their original magnetic strength. The image con-

structed from this time constant is called T1 (Fig. 1-2). On

the other hand, those protons that achieved a higher energy

level

(were not cancelled-out) lose their energy more

rapidly as they return to their original state; the image con-

structed from this time constant is T2 (Fig. 1-3). The cre-

1-1

Computed Tomography (CT) in the axial plane of a patient

ation of a T1-weighted image versus a T2-weighted image is

with subarachnoid hemorrhage. Bone is white, acute blood (white)

based on a variation in the times used to receive the “echo”

outlines the subarachnoid space, brain is grey, and cerebrospinal fluid

in third and lateral ventricles is black.

from the relaxed protons.

Introduction and Reader’s Guide

The Brain and Related Structures in MRI

NORMAL

Bone

Very black

Air

Very black

Muscle

Dark grey

White matter

Light grey

Dark grey

Grey matter

Dark grey

Light grey

Fat

White

Grey

CSF

Very black

Very white

ABNORMAL

1-2

A sagittal T1 weighted Magnetic Resonance Image (MRI).

Brain is grey and cerebrospinal fluid is black.

Edema

Dark grey

Light grey to white

Tumor

Variable

Enhanced tumor

White

(Rarely done)

Acute infarct

Dark grey

Light grey to white

The following table summarizes the white to black inten-

Subacute infarct

Dark grey

Light grey to white

sities seen in MRI images that are T1-weighted versus T2-

Acute ischemia

Dark grey

Light grey to white

weighted. It should be emphasized that a number of varia-

Subacute ischemia

Dark grey

Light grey to white

tions on these two general MRI themes are routinely seen in

the clinical environment.

The advantages of MRI are 1) it can be manipulated to vi-

sualize a wide variety of abnormalities or abnormal states

Chapter 2

within the brain; and 2) it can show great detail of the brain

This chapter presents 1) the gross anatomy of the spinal cord

in normal and abnormal states. The disadvantages of MRI

and its principal arteries; 2) the external morphology of the

are 1) it does not show acute or subacute subarachnoid hem-

brain, accompanied by MRIs and drawings of the vascula-

orrhage or hemorrhage into the substance of the brain in any

ture patterns from the same perspective; 3) cranial nerves

detail; 2) it takes a much longer time to do and, therefore,

as seen in specimens and in MRI; and 4) the meninges and

is not useful in acute situations or in some types of trauma;

ventricular spaces. Emphasis is placed on correlating exter-

3) it is, comparatively, much more expensive than CT, and

nal brain and spinal cord anatomy with the respective vas-

4) the scan is extremely loud and may require sedation in

cular patterns and on correlating external brain structures

children.

and cranial nerves as seen in specimens with how the same

The ensuing discussion briefly outlines the salient features

structures appear in MRI. Information concerning the orga-

of individual chapters. In some sections, considerable flexi-

nization of the meninges includes clinical correlations, ex-

bility has been designed into the format; at these points,

amples of extradural, so-called “subdural”, and subarach-

some suggestions are made as to how the atlas can be used.

noid hemorrhages in CT and examples of cisterns in MRI.

In addition, new clinical correlations and examples have

The section showing the structure and relations of the ven-

been included and a new chapter of USMLE-style review

tricular system now includes samples of hemorrhage into

questions has been added.

lateral, third, and fourth ventricles.

Chapter 3

The dissections in Chapter 3 offer views of some of those

brain structures introduced in Chapter 2. Certain structures

and/or structural relationships—for example, the orienta-

tion of the larger association bundles—are particularly

suited to such a presentation. This chapter uses a represen-

tative series of dissected views to provide a broader basis for

learning human neuroanatomy. Because it is not feasible to

illustrate every anatomic feature, the views and structures

selected are those that are usually emphasized in medical

neurobiology courses. These views provide basic informa-

1-3

A sagittal T2 weighted Magnetic Resonance Image (MRI).

Brain is grey, blood vessels frequently appear black, and cerebrospinal

tion necessary to make more detailed dissections, if appro-

fluid is white.

priate, in a particular learning situation.

Introduction and Reader’s Guide

Chapter 4

nuclei of cranial nerves. This scheme continues rostrally

into the caudal nuclei of the dorsal thalamus and the poste-

The study of general morphology of the hemisphere and

rior limb of the internal capsule. In addition to the coloring

brainstem is continued in the two sections of Chapter 4. The

of the artwork, each page has a key that specifies the struc-

first section contains a representative series of unstained

ture and function of each colored structure. This approach

coronal slices of brain, each of which is accompanied, on the

emphasizes anatomical-clinical integration.

same page, by MRIs. The brain slice is labeled (by complete

Semidiagrammatic representations of the internal blood

names), and the MRIs are labeled with a corresponding ab-

supply to the spinal cord, medulla, pons, midbrain, and fore-

breviation. The second section contains a series of unstained

brain follow each set of line drawings and stained sections.

brain slices cut in the axial plane, each of which is accompa-

This allows the immediate, and convenient, correlation of

nied, again on the same page, by MRIs. Labeling of the axial

structure with its blood supply as one is studying the inter-

slices is as done for the coronal slices.

nal anatomy of the neuraxis. In addition, tables that summarize

The similarities between the brain slices and the MRIs are

the vascular syndromes of the spinal cord, medulla, pons, midbrain,

remarkable, and this style of presentation closely integrates

and forebrain are located on the pages facing each of these vas-

anatomy in the slice with that as seen in the corresponding

cular drawings. While learning or reviewing the internal

MRI. Because the brain, as sectioned at autopsy or in clini-

blood supply to these parts of the neuraxis, one can also cor-

cal pathologic conferences, is viewed as an unstained speci-

relate the deficits seen when the same vessels are occluded.

men, the preference here is to present the material in a for-

It is essential to successful diagnosis to develop a good un-

mat that will most closely parallel what is seen in these

derstanding of what structure is served by what vessel.

clinical situations.

The diencephalon and basal nuclei section of this chapter

uses ten cross-sections to illustrate internal anatomy. It

should be emphasized that 8 of these 10 sections (those parallel to

Chapter 5

each other) are all from the same brain.

This chapter has been revised with special emphasis on in-

The internal anatomy of the brainstem is commonly

creasing the correlation between anatomical and clinical in-

taught in an anatomical orientation. That is, posterior struc-

formation. This new edition retains the quality and inherent

tures, such as the vestibular nuclei and colliculi, are “up” in

strengths of the line drawings and the stained sections being

the image, while anterior structures, such as the pyramid

located on facing pages in this chapter. However, an innov-

and crus cerebri, are “down” in the image. However, when

ative approach (described below) is introduced that allows

the brainstem is viewed in the clinical setting, as in CT or

the use of these images in their classic Anatomical Orienta-

MRI, this orientation is reversed. In the clinical orientation,

tion and, at the same time, their conversion to the Clinical

posterior structures (4th ventricle, colliculi) are “down” in

Orientation so universally recognized and used in clinical

the image while anterior structures (pyramid, basilar pons,

imaging techniques.

crus cerebri) are “up” in the image.

Chapter 5 consists of six sections covering, in sequence,

Recognizing that many users of this book are pursuing a

the spinal cord, medulla oblongata, cerebellar nuclei, pons,

health care career (as a practitioner or teacher of future clin-

midbrain, and diencephalon and basal nuclei, all with MRI.

icians), it is essential to introduce MRI and CT of the brain-

In this format, the right-hand page contains a complete im-

stem into chapter 5. This accomplishes two important points.

age of the stained section. The left-hand page contains a la-

First, it allows correlation of the size, shape, and configura-

beled line drawing of the stained section, accompanied by a

tion of brainstem sections (line drawings and stained slices)

figure description, and a small orientation drawing. The sec-

with MRI and CT at comparable levels. Second, it offers the

tion part of the line drawing is printed in a 60% screen of

user the opportunity to visualize how nuclei, tracts (and their

black, and the leader lines and labels are printed at 100%

somatotopy) and vascular territories are represented in MRI

black. This gives the illustration a sense of depth and tex-

and CT. Understanding the brain in the Clinical Orientation

ture, reduces competition between lines, and makes the il-

(as seen in MRI or CT) is extremely important in diagnosis.

lustration easy to read at a glance.

To successfully introduce MRI and CT in the brainstem por-

Beginning with the first spinal cord level (coccygeal, Fig-

tion of chapter 5, a continuum from Anatomical Orientation

ure 5-1), the long tracts that are most essential to under-

to Clinical Orientation to MRI needs to be clearly illustrated.

standing how to diagnose the neurologically impaired

This is achieved by 1) placing a small version of the colorized

patient are colored. These tracts are the posterior column-

line drawing on the facing page (page with the stained section)

medial lemniscus system, the lateral corticospinal tract, and

in Anatomical Orientation; 2) showing how this image is

the anterolateral system. In the brainstem, these tracts are

flipped top to bottom into a Clinical Orientation; and 3) fol-

joined by the colorized spinal trigeminal tract, the ventral

lowing this flipped image with (usually) T1 and T2 MRls at

trigeminothalamic tract, and all of the motor and sensory

levels comparable to the accompanying line drawing and

Introduction and Reader’s Guide

stained section (Fig. 1-4). This approach retains the anatom-

ical strengths of the spinal cord and brainstem sections of

chapter 5 but allows the introduction of important concepts

regarding how anatomical information is arranged in images

utilized in the clinical environment.

Every effort has been made to use MRI and CT that match,

as closely as possible, the line drawings and stained sections in

the spinal cord and brainstem portions of chapter 5. Recog-

nizing that this match is subject to the vicissitudes of angle and

individual variation, special sets of images were used in chap-

ter 5. The first set consisted of T1- and T2-weighted MRI

1-5

Computed Tomography (CT) of a patient following injection

generated from the same individual; these are identified, re-

of a radiopaque contrast media into the lumbar cistern. In this exam-

spectively, as “MRI, T1-weighted” and “MRI, T2-weighted”

ple, at the medullary level (a cisternogram), neural structures appear

in chapter 5. The second set consisted of CT images from a

grey and the subarachnoid space appears light.

patient who had an injection of the radiopaque contrast me-

dia Isovue-M^R 200 (iopamidol injection 41 %) into the lum-

The juxtaposition of MRI to stained section extends into

bar cistern. This contrast media diffused throughout the spinal

the forebrain portion of chapter 5. Many anatomic features

and cranial subarachnoid spaces, outlining the spinal cord and

seen in the forebrain stained sections are easily identified in

brainstem (Fig. 1-5). Images at spinal levels show neural

the adjacent MRI. These particular MRI are not labeled so

structures as grey surrounded by a light subarachnoid space;

as to allow the user to develop and practice his/her inter-

this is a “CT myelogram”. A comparable image at brainstem

pretive skills. The various subsections of chapter 5 can be

levels (grey brain, light CSF) is a “CT cisternogram”. These

used in a variety of ways and will accommodate a wide range

designations are used in chapter 5. While all matches are not

of student and/or instructor preferences.

perfect, not all things in life or medicine are, the vast major-

ity of matches between MRI, CT, and drawings/sections are

Chapter 6

excellent and clearly demonstrate the intended points.

The three-dimensional anatomy of internal structures in the

CNS can also be studied in stained sections that correlate sim-

ilar structures in different planes. The photographs of stained

axial and sagittal sections and of MRIs in Chapter 6 are orga-

nized to provide four important levels of information. First,

Anatomical orientation

Clinical orientation

the general internal anatomy of brain structures can be easily

identified in each photograph. Second, axial photographs are

on left-hand pages and arranged from dorsal to ventral (Fig-

ures 6-1 to 6-9), whereas sagittal photographs are on right-

hand pages and arranged from medial to lateral (Figures 6-2

to 6-10). This setup, in essence, provides complete repre-

sentation of the brain in both planes for use as independent

MRI, T1 weighted image

study sets (axial only, sagittal only) or as integrated/corre-

lated sets (compare facing pages). Third, because axial and

sagittal sections are on facing pages and the plane of section of

each is indicated on its companion by a heavy line, the reader

can easily visualize the positions of internal structures in more

MRI, T2 weighted image

than one plane and develop a clear concept of three-dimen-

sional topography. In other words, one can identify structures

dorsal or ventral to the axial plane by comparing them with

the sagittal, and structures medial or lateral to the sagittal

plane by comparing them with the axial. Such comparisons fa-

cilitate a more full understanding of three-dimensional rela-

CT cisternogram

tionships in the brain. Fourth, the inclusion of MRIs with rep-

resentative axial and sagittal stained sections provides

1-4

An example showing anatomical and clinical orientations of a

excellent examples of the fact that structures seen in the

brainstem level and the corresponding T1 MRI, T2 MRI, and CT cister-

teaching laboratory are easy to recognize in clinical images.

nogram. For additional examples and details see chapter 5, pages 84-133.

Introduction and Reader’s Guide

These MRIs are also not labeled so as to allow the user to de-

general format as the preceding figures. Photocopies of

velop his/her interpretive skills.

these blank master drawings can be used by the student for

learning and/or review of any pathway and by the instruc-

tor to teach additional pathways not included in the atlas or

Chapter 7

as a substrate for examination questions. The flexibility of

This chapter provides summaries of a variety of clinically

information as presented in Chapter 7 extends equally to

relevant CNS tracts and/or pathways and has four features

student and instructor.

that enhance student understanding. First, the inclusion of

pathway information in atlas format broadens the basis one

Chapter 8

can use to teach functional neurobiology. This is especially

the case when pathways are presented in a style that en-

This chapter contains a series of angiograms (arterial and

hances the development of diagnostic skills. Second, each

venous phases), magnetic resonance angiography (MRA)

drawing illustrates, in line color, a given pathway com-

images, and magnetic resonance venography (MRV) im-

pletely, showing its 1) origins, longitudinal extent, course

ages. The angiograms are shown in lateral and anterior-

throughout the neuraxis and termination; 2) laterality—an

posterior projections—some as standard views with corre-

all-important issue in diagnosis; 3) point of decussation, if

sponding digital subtraction images. MRA and MRV tech-

applicable; 4) position in representative cross sections of the

nology are noninvasive methods that allow for the visualiza-

brainstem and spinal cord; and 5) the somatotopic organi-

tion of arteries (MRA) and veins and venous sinuses (MRV).

zation of fibers within the pathway, if applicable. The blood

There are, however, many situations when both arteries and

supply to each pathway is reviewed on the facing page.

veins are seen with either method. Use of MRA and MRV

Third, a brief summary mentions the main neuroactive sub-

is commonplace, and this technology is an important diag-

stances associated with cells and fibers composing particular

nostic tool. A number of new vascular images have been in-

segments of the pathway under consideration. The action of

cluded in this revised version of Chapter 8.

the substance, if widely agreed on, is indicated as excitatory

(

) or inhibitory (

). This allows the reader to closely correlate

Chapter 9

a particular neurotransmitter with a specific population of projec-

tion neurons and their terminals. The limitations of this ap-

A primary goal in the study of functional human neurobi-

proach, within the confines of an atlas, are self-evident. The

ology is to become a competent health care professional.

transmitters associated with some pathways are not well

Another, and equally significant, goal is to pass examina-

known; consequently, such information is not provided for

tions. These may be course examinations, the National

some connections. Also, no attempt is made to identify sub-

Board Subject Exam (some courses require these), or stan-

stances that may be colocalized, to discuss their synthesis or

dardized tests, such as the USMLE Step 1 and Step 2, given

degradation, or to mention all neurotransmitters associated

at key intervals and taken by all students.

with a particular cell group. The goal here is to introduce

The questions comprising chapter 9 were generated in

the reader to selected neurotransmitters and to integrate and

the recognition that examinations are an essential part of the

correlate this information with a particular pathway, circuit,

educational process. Whenever possible, and practical,

or connection. Fourth, the clinical correlations that accompany

these questions are in the USMLE Step 1 style (single best

each pathway drawing provide examples of deficits resulting from

answer). These questions emphasize 1) anatomical and clin-

lesions, at various levels in the neuraxis, of the fibers composing that

ical concepts and correlations; 2) the application of basic hu-

specific pathway. Also, examples are given of syndromes or

man neurobiology to medical practice; and 3) how neuro-

diseases in which these deficits are seen. The ways in which

logical deficits and diseases relate to damage in specific parts

these clinical correlations can be used to enrich the learning

of the nervous system. In general, the questions are grouped

process are described in Figure 7-3 on page 176.

by chapter. However, in some instances, questions draw on

The drawings in this section were designed to provide the

information provided in more than one chapter. This is

maximum amount of information, to keep the extraneous

sometimes essential in an effort to make appropriate

points to a minimum, and to do it all in a single, easy-to-fol-

structural/functional/clinical correlations. At the end of

low illustration. A complete range of relevant information

each group of questions the correct answers are provided

is contained in each drawing and in its description as ex-

and explained. Included with the explanation is a reference

plained in the second point above.

to the page (or pages) containing the answer, be that answer

Because it is not possible to anticipate all pathways that

in the text or in a figure. Although not exhaustive, this list

may be taught in a wide range of neurobiology courses, flex-

of questions should provide the user of this atlas with an ex-

ibility has been designed into Chapter 7. The last figure in

cellent opportunity for self-assessment covering a broad

each section is a blank master drawing that follows the same

range of clinically relevant topics.

Introduction and Reader’s Guide

Rationale for Labels and Abbreviations

o universally accepted way to identify specific features

Chapters 2 and 4). This uses the complete word(s) on the

or structures in drawings or photographs exists. The

larger image of a brain structure while using the shorter ab-

variety of methods seen in currently available atlases reflects

breviation on the smaller image of the MRI.

the personal preferences of the authors. Such is the case in

The abbreviations used in this atlas do not clutter the il-

the present endeavor. The goal of this atlas is to present ba-

lustration; they permit labeling of all relevant structures and

sic functional and clinical neuroanatomy in an understand-

are adequately informative while stimulating the think-

able and useful format.

ing-learning process. The abbreviations are, in a very real

Among currently available atlases, most figures are la-

sense, mnemonics. When learning gyri and sulci of the oc-

beled with either the complete names of structures or with

cipital lobe, for example, one realizes that the abbreviation

numbers or letters that are keyed to a list of the complete

“LinGy” in the atlas could only mean “lingual gyrus.” It could

names. The first method immediately imparts the greatest

not be confused with other structures in other parts of the

amount of information; the second method is the most suc-

nervous system. Regarding the pathways, “RuSp” could

cinct. When using the complete names of structures, one

mean only “rubrospinal tract” and “LenFas,” the “lenticular

must exercise care to not compromise the quality or size of

fasciculus.” As the reader learns more and more terminol-

the illustration, the number of structures labeled, or the size

ogy from lectures and readings, he or she will be able to use

of labels used. Although the use of single letters or numbers

these abbreviations with minimal reference to the accompa-

results in minimal clutter on the figure, a major drawback is

nying list. In addition, a subtle advantage of this method of

the fact that the same number or letter may appear on sev-

labeling is that, as the reader looks at the abbreviation and

eral different figures and designate different structures in all

momentarily pauses to ponder its meaning, he or she may

cases. Consequently, no consistency occurs between num-

form a mental image of the structure and the complete

bers and letters and their corresponding meanings as the

word. Because neuroanatomy requires one to conceptualize

reader examines different figures. This atlas uses a combi-

and form mental images to more clearly understand CNS

nation of complete words and abbreviations that are clearly

relationships, this method seems especially useful.

recognized versions of the complete word.

References:

In response to suggestions made by those using this book

Bruxton, RB. Introduction to Functional Magnetic Resonance

over the years, the number of abbreviations in the sixth edi-

Imaging, Principles and Techniques. Cambridge: Cambridge

tion has been reduced, and the number of labels using the

University Press, 2002.

complete name has been increased. Simultaneously, com-

Grossman, CB. Magnetic Resonance Imaging and Computed To-

plete names and abbreviations have been used together in

mography of the Head and Spine.

2^nd Ed. Baltimore:

some chapters to the full advantage of each method. For ex-

Williams & Wilkins, 1996.

ample, structures are labeled on a brain slice by the com-

Lee, SH, Roa, KCVG, and Zimmerman, RA. Cranial MRI

plete name, but the same structure in the accompanying

and CT. 4^th Ed. New York: McGraw-Hill Health Profes-

MRI is labeled with a corresponding abbreviation (see

sions Division, 1999.

The Spinal Cord

Posterior View

Sulci:

Posterior median

Posterior intermediate

Posterolateral

C₇ Posterior root

Spinal (posterior root) ganglion

Fasciculus gracilis

Fasciculus cuneatus

Anterior View

Anterior spinal artery

C₇ Anterior root

Anterior radicular

artery

Anterior funiculus

Anterior median fissure

2-2

Posterior (upper) and anterior (lower) views showing details

of the spinal cord as seen in the C₇ segment. The posterior (dorsal) root

ganglion is partially covered by dura and connective tissue.

Posterior spinal arteries

Arterial

vasocorona

Basilar artery

Posterior inferior

cerebellar arteries

Vertebral arteries

Anterior spinal artery

Posterior spinal

medullary artery

Posterior radicular

artery (on dorsal root)

Sulcal arteries

Anterior spinal

medullary artery

Anterior radicular artery

(on ventral root)

Segmental artery

2-3

Semidiagrammatic representation showing the origin and gen-

medullary arteries) arise at intermittent levels and serve to augment

eral location of principal arteries supplying the spinal cord. The ante-

the blood supply to the spinal cord. The artery of Adamkiewicz is an

rior and posterior radicular arteries arise at every spinal level and serve

unusually large spinal medullary artery arising usually on the left in low

their respective roots and ganglion. The anterior and posterior spinal

thoracic or upper lumbar levels (T₉-L₁). The arterial vasocorona is a

medullary arteries (also called medullary feeder arteries or segmental

diffuse anastomotic plexus covering the cord surface.

External Morphology of the Central Nervous System

Thoracic

cord

Dura and

arachnoid

LuSaCd

Lumbar and

sacral cord

(LuSaCd)

SaCoCd

Sacral and

coccygeal

Lumbar

cord

cistern

(SaCoCd)

FTInt

Conus

medullaris

CaEq

Filum

terminale

internum

(FTInt)

Cauda

equina

(CaEq)

Posterior

root

ganglion

Dura and

arachnoid

2-4

Overall posterior (A,B) and sagittal MRI (C, T2-weighted)

end of the spinal cord. This space contains the anterior and posterior

views of the lower thoracic, lumbar, sacral, and coccygeal spinal cord

roots from the lower part of the spinal cord that collectively form the

segments and the cauda equina. The dura and arachnoid are retracted

cauda equina. The filum terminale internum also descends from the

in A and B. The cauda equina is shown in situ in A, and in B the nerve

conus medullaris through the lumbar cistern to attach to the inner sur-

roots of the cauda equina have been spread laterally to expose the conus

face of the dural sac. The dural sac ends at about the level of the S2 ver-

medullaris and filum terminale internum. This latter structure is also

tebra and is attached to the coccyx by the filum terminale externum

called the pial part of the filum terminale. See Figures 5-1 and 5-2 on

(also see Fig. 2-47 on page 47). A lumbar puncture is made by insert-

pages 84-87 for cross-sectional views of the cauda equina.

ing a large gauge needle (18-22 gauge) between the L3 and L4 verte-

In the sagittal MRI (C), the lower portions of the cord, the filum

bra or L4 and L5 vertebra and retrieving a sample of cerebrospinal fluid

terminale internum, and cauda equina are clearly seen. In addition, the

from the lumbar cistern. This sample may be used for a number of di-

intervertebral discs and the bodies of the vertebrae are clear. The lum-

agnostic procedures.

bar cistern is an enlarged part of the subarachnoid space caudal to the

The Brain: Lobes

Central sulcus

Precentral sulcus

Postcentral sulcus

Lobes

Parietooccipital

sulcus

Frontal

Parietal

Temporal

Occipital

Preoccipital

Lateral sulcus

notch

Limbic

Insular

Central sulcus

Paracentral sulcus

Marginal sulcus (marginal

ramus of the cingulate

Cingulate sulcus

sulcus)

Corpus callosum

Parietooccipital

sulcus

Fornix

Diencephalon

Calcarine

sulcus

Preoccipital notch

Collateral sulcus

2-5

Lateral (A) and medial (B) views of the cerebral hemisphere

of the cortex is made up of long and short gyri that are separated from

showing the landmarks used to divide the cortex into its main lobes.

each other by the central sulcus of the insula. The insula, as a whole, is

On the lateral aspect, the central sulcus (of Rolando) separates

separated from the adjacent portions of the frontal, parietal, and tem-

frontal and parietal lobes. The lateral sulcus (of Sylvius) forms the bor-

poral opercula by the circular sulcus.

der between frontal and temporal lobes. The occipital lobe is located

On the medial aspect, the cingulate sulcus separates medial portions

caudal to an arbitrary line drawn between the terminus of the parieto-

of frontal and parietal lobes from the limbic lobe. An imaginary con-

occipital sulcus and the preoccipital notch. A horizontal line drawn

tinuation of the central sulcus intersects with the cingulate sulcus and

from approximately the upper two-thirds of the lateral fissure to the

forms the border between frontal and parietal lobes. The parieto-

rostral edge of the occipital lobe represents the border between pari-

occipital sulcus and an arbitrary continuation of this line to the preoc-

etal and temporal lobes. The insular cortex (see also Figs. 2-46 on page

cipital notch separate the parietal, limbic, and temporal lobes from the

45 and 3-1 on page 56) is located internal to the lateral sulcus. This part

occipital lobe.

The Brain: Lobes

Precentral gyrus (primary somatomotor cortex)

Posrcentral gyrus (primary somatosens ry cortex)

Anterior paracentral gyrus (somatomotor)

Posterior paracentral gyrus (somatosensory)

Left

inferior

visual

quadrant

2-7

Lateral (A) and medial (B) views of the cerebral hemisphere

ing the hand and upper extremity areas, and the medial third repre-

showing the somatotopic organization of the primary somatomotor

senting the trunk and the hip. Lesions of the somatomotor cortex re-

and somatosensory cortices. The lower extremity and foot areas are lo-

sult in motor deficits on the contralateral side of the body while lesions

cated on medial aspects of the hemisphere in the anterior paracentral

in the somatosensory cortex result in a loss of sensory perception from

(motor) and the posterior paracentral (sensory) gyri. The remaining

the contralateral side of the body.

portions of the body extend from the margin of the hemisphere over

The medial surface of the right hemisphere (B) illustrates the posi-

the convexity to the lateral sulcus in the precentral and postcentral

tion of the left portions of the visual field. The inferior visual quadrant

gyri.

is located in the primary visual cortex above the calcarine sulcus while

In general, the precentral gyrus can be divided into three regions:

the superior visual quadrant is found in the cortex below the calcarine

the lateral third representing the face area, the middle third represent- sulcus.

The Brain: Gross Views, Vasculature, and MRI

Central sulcus

Anterior and posterior

parietal branches of MCA

Rolandic branches

of MCA

Angular branches

Prerolandic branches

of MCA

Posterior temporal

branches of MCA

Orbitofrontal branches

of MCA

Orbital branches

of anterior cerebral artery

Middle temporal

branches of MCA

Middle cerebral artery (MCA)

in lateral sulcus

Anterior temporal

branches of MCA

2-12

Lateral view of the right cerebral hemisphere showing the

sphere represent the M₄ segment. Terminal branches of the posterior

branching pattern of the middle cerebral artery. Gyri and sulci can be

and anterior cerebral arteries course over the edges of the temporal and

identified by comparison with Figure 2-11 (facing page). The middle

occipital lobes, and parietal and frontal lobes, respectively (see Figure

cerebral artery initially branches in the depths of the lateral sulcus (as

2-9 on page 17). See Figure 8-1 (p. 240) for a comparable angiogram

M₂ and M₃ segments); these branches seen on the surface of the hemi-

of the middle and anterior cerebral arteries.

Rolandic vein

Greater anastomotic vein (Trolard)

Superior sagittal sinus

Superior cerebral veins

Superior cerebral

veins

Inferior anastomotic

vein (Labbé)

Straight sinus

Superficial middle

Sinus confluens

cerebral vein

Transverse sinus (TS)

To sphenoparietal sinus

To cavernous sinus

Inferior cerebral veins

To sphenoparietal sinus

Inferior cerebral veins

Occipital sinus

to sphenoparietal sinus

Temporal cerebral veins

To sigmoid sinus

2-13

Lateral view of the right cerebral hemisphere showing the lo-

sinuses are also indicated. See Figures 8-2 (p. 241) and 8-11 (p. 250)

cations of sinuses and the locations and general branching patterns of

for comparable angiogram and MRV of the sinuses and superficial

veins. Gyri and sulci can be identified by comparison with Figure 2-11

veins.

(facing page). Communications between veins and sinuses or between

The Brain: Gross Views, Vasculature, and MRI

Orbitofrontal branches

of MCA

Orbital branches of ACA

Middle cerebral

artery (MCA)

Anterior cerebral

MCA in lateral sulcus

artery (ACA)

Lenticulostriate

branches of MCA

Anterior temporal

Posterior cerebral

branch of PCA

artery (PCA)

(P₃ segment)

Posterior temporal

branch of PCA

(P₃ segment)

Parieto-occipital

branch of PCA

(P₄ segment)

Calcarine branch of PCA

(P₄ segment)

2-15

Ventral view of the cerebral hemisphere with the brainstem

on page 25. Shown here are P₃ (origin of temporal arteries) and P₄ (ori-

removed, which shows the branching pattern of the posterior cerebral

gin of calcarine and parietooccipital arteries) segments. Gyri and sulci

artery (PCA) and some branches of the anterior and middle cerebral

can be identified by comparison with Figure 2-14 (facing page).

arteries. The P₁ and P₂ segments of the PCA are shown on Figure 2-21

Sphenoparietal sinus

Intercavernous sinuses

Cavernous sinus

Posterior

Superior petrosal sinus

Pineal

Inferior petrosal sinus

Great cerebral vein

Sigmoid sinus

Straight sinus

Internal jugular vein

—inferior sagittal sinus

—superior cerebellar veins

Transverse sinus (TS)

Sinus confluens

2-16

Ventral view of the cerebral hemisphere, with brainstem re-

are the main tributaries of that sinus. See Figures 8-5 (p. 245), 8-9

moved, showing the locations and relationships of the main sinuses.

(p. 248), and 8-11 (p. 250) for comparable MRV of the transverse

Gyri and sulci can be identified by comparison with Figure 2-14 (facing

sinus.

page). The listings preceded by an en-dash (-) under principal sinuses

The Brain: Gross Views, Vasculature, and MRI

Anterior cerebral artery

Internal carotid artery

Middle cerebral artery (MCA)

Optic nerve,

chiasm, and tract

Posterior communicating artery

Lenticulostriate

Oculomotor nerve

branches of MCA

Superior cerebellar artery

Posterior cerebral artery

Trochlear nerve

Basilar artery

Trigeminal nerve

Abducens nerve

Facial and

AICA

vestibulocochlear nerves

Anterior inferior

Branches of AICA

cerebellar artery (AICA)

Posterior inferior

PICA

cerebellar artery (PICA)

PSA

Vertebral artery

Branches of PICA

Posterior spinal artery (PSA)

Anterior spinal artery

2-18

Ventral view of the cerebral hemispheres, diencephalon,

son with Figure 2-17 (facing page). Details of the cerebral arterial cir-

brainstem, and cerebellum, which shows the arterial patterns created

cle and the vertebrobasilar arterial pattern are shown in Figure 2-21 on

by the internal carotid and vertebrobasilar systems. Note the cerebral

page 25. See Figure 8-9 and 8-10 (pp. 248-249) for comparable MRA

arterial circle (of Willis). Gyri and sulci can be identified by compari-

of the cerebral arterial circle and its major branches.

Superior ophthalmic vein

-from area of ophthalmic artery

Sphenoparietal sinus

-middle cerebral vein

Cavernous sinus

-cerebral vein

Superior petrosal sinus

Intercaverous sinuses

-cerebellar veins

-inferior cerebral veins

-tympanic veins

Inferior petrosal sinus

-veins of pons and medulla

Basilar plexus

-auditory veins

Sigmoid sinus

Internal jugular vein

Transverse sinus

Anterior vertebral

-emissary veins

venous plexus

-inferior cerebral veins

-inferior cerebellar veins

Occipital sinus

Sinus confluens

-posterior internal vertebral

-straight sinus

venous plexus

-superior sagittal sinus

2-19

Ventral view of the cerebral hemispheres, diencephalon, principal sinuses and veins. The listings preceded by a dash (-) under

brainstem, and cerebellum showing the locations and relationships of principal sinuses are the main tributaries of that sinus.

The Brain: Gross Views, Vasculature, and MRI

Vessels

Structures

Medial striate artery

Anterior communicating artery

Olfactory tract

Anterior cerebral artery

Optic chiasm

Optic nerve

Posterior communicating artery

Anterior perforated substance

Ophthalamic artery

Anterior and polar

Internal carotid artery

temporal arteries

Uncal artery

Middle cerebral

artery

Optic tract

Mammillary body

Infundibulum

Lenticulostriate arteries

Crus cerebri

Anterior choroidal artery

Posterior cerebral artery

Oculomotor nerve (III)

Posterior choroidal arteries

Trochlear nerve (IV)

Quadrigeminal artery

Basilar pons

Superior cerebellar artery

Trigeminal nerve (V)

Abducens nerve (VI)

Pontine arteries

Facial nerve (VII)

Middle cerebellar

peduncle

Basilar artery

Vestibulocochlear

nerve (VIII)

Choroid plexus

Anterior inferior

Glossopharyngeal nerve (IX)

cerebellar artery

Vagus nerve (X)

Labyrinthine artery

Accessory nerve (XI)

Posterior inferior

cerebellar artery

Hypoglossal nerve (XII)

Olive (inferior);

Posterior spinal artery

olivary eminence

Vertebral artery

Cerebellum

Pyramid

Anterior spinal artery

2-21

Ventral view of the brainstem showing the relationship of

p. 242 for details). Lateral to the internal carotid bifurcation is the

brain structures and cranial nerves to the arteries forming the verte-

M₁ segment of the middle cerebral artery (MCA), which divides and

brobasilar system and the cerebral arterial circle (of Willis). The pos-

continues as the M₂ segments (branches) on the insular cortex. The

terior spinal artery usually originates from the posterior inferior

M₃ branches of the MCA are those located on the inner surface of the

cerebellar artery (left), but it may arise from the vertebral (right).

opercula, and the M₄ branches are located on the lateral aspect of the

Although the labyrinthine artery may occasionally branch from the

hemisphere. Between the basilar bifurcation and the posterior com-

basilar (right), it most frequently originates from the anterior infe-

municating artery is the P₁ segment of the posterior cerebral artery;

rior cerebellar artery (left). Many vessels that arise ventrally course

P₂ is between the posterior communicator and the first temporal

around the brainstem to serve dorsal structures. The anterior cere-

branches. See Figure 8-9, 8-10, and 8-12 (pp. 248, 249, 251) for

bral artery consists of A₁ (between the internal carotid bifurcation

comparable MRA of the cerebral arterial circle and vertebrobasilar

and the anterior communicating artery) and segments A₂-A₅ which

system. See Figure 8-12 on p. 251 for blood supply of the choroid

are distal to the anterior communicating artery (see Figure 8-3 on

plexus.

The Brain: Gross Views, Vasculature, and MRI

Fornix

Choroid plexus, third ventricle

Optic tract

Posterior choroidal arteries

Thalamogeniculate artery

Lateral geniculate body

Dorsal thalamus

Posterior cerebral artery

Mammillary body

Medial geniculate body

Quadrigeminal artery

Superior colliculus

Posterior communicating

Crus cerebri

artery

Internal carotid artery

Brachium of inferior colliculus

Inferior colliculus

Oculomotor nerve

Superior cerebellar artery

Trochlear nerve

Trigeminal nerve

Motor root

Sensory root

Superior cerebellar peduncle

Anterior medullary velum

Basilar artery

Middle cerebellar peduncle

Anterior inferior

cerebellar artery

Vestibulocochlear nerve

Facial nerve

Labyrinthine artery

Posterior inferior

Abducens nerve

cerebellar artery

Glossopharyngeal nerve

Choroid plexus,

Vagus nerve

fourth ventricle

Hypoglossal nerve

Restiform body

Accessory nerve

Cuneate tubercle

Gracile tubercle

Posterior inferior cerebellar artery

Posterior spinal artery

Anterior spinal artery

Vertebral artery

2-24

Lateral view of the brainstem and thalamus showing the rela-

tively, are shown as dashed lines. Compare with Figure 2-22 on the fac-

tionship of structures and cranial nerves to arteries. Arteries that serve

ing page. See Figure 8-7 (p. 246) for comparable angiogram of the ver-

dorsal structures originate from ventrally located parent vessels. The

tebrobasilar system. See Figure 8-12 on p. 251 for blood supply of the

approximate positions of the posterior spinal and labyrinthine arteries,

choroid plexus.

when they originate from the vertebral and basilar arteries, respec-

Anterior cerebral artery

communicating

artery

Middle cerebral artery (M1)

Hypothalamus

Posterior communicating

Crus cerebri

artery

Red nucleus

Posterior cerebral artery

Cerebral aqueduct

Cortical branches of

posterior cerebral artery

2-25

A proton density MRI through basal regions of the hemi-

2-21 on page 25. See Figure 8-9 and 8-10 (pp. 248-249) for compa-

sphere and through the midbrain showing several major vessels that

rable MRA of the cerebral arterial circle.

form part of the cerebral arterial circle (of Willis). Compare to Figure

External Morphology of the Central Nervous System

Anterior paracentral gyrus (APGy)

Central sulcus (CSul)

Paracentral sulcus (ParCSul)

Posterior paracentral gyrus (PPGy)

Precentral sulcus (PrCSul)

Marginal sulcus (MarSul)

Precuneus (PrCun)

Cingulate gyrus (CinGy)

Superior frontal

gyrus (SFGy)

Parieto-occipital

sulcus (POSul)

Cingulate sulcus

Cuneus (Cun)

(CinSul)

Calcarine sulcus

(CalSul)

Lingual gyrus

(LinGy)

Sulcus of corpus

callosum (SulCC)

Isthmus of cingulate gyrus

Paraterminal gyri

Occipitotemporal gyri

Parolfactory gyri (ParolfGy)

Parahippocampal gyrus

Uncus

Temporal pole

Rhinal sulcus

APGy

PrCSul

CSul

PPGy

ParCSul

MarSul

SulCC

CinGy

PrCun

CinSul

POSul

ParolfGy

Cun

CalSul

LinGy

MarSul

SFGy

Corpus callosum

POSul

CalSul

Colloid cyst

Internal cerebral

vein

2-26

Midsagittal view of the right cerebral hemisphere and dien-

A colloid cyst (colloid tumor) is a congenital growth usually dis-

cephalon, with brainstem removed, showing the main gyri and sulci

covered in adult life once the flow of CSF through the interventricular

and two MRI (both T1-weighted images) showing these structures

foramina is compromised (obstructive hydrocephalus). The patient

from the same perspective. The lower MRI is from a patient with a

may have headache, unsteady gait, weakness of the lower extremities,

small colloid cyst in the interventricular foramen. When compared to

visual or somatosensory disorders, and/or personality changes or con-

the upper MRI, note the enlarged lateral ventricle with resultant thin-

fusion. Treatment is usually by surgical removal.

ning of the corpus callosum.

The Brain: Gross Views, Vasculature, and MRI

Internal frontal branches

Paracentral branches

Callosomarginal branch

Internal parietal branches

of ACA

Parietooccipital

Pericallosal branch

branches of PCA

of ACA

Frontopolar branches

of ACA

Orbital branches of ACA

Anterior cerebral artery (ACA)

Calcarine branch of PCA

Posterior temporal branches of PCA

Posterior cerebral artery (PCA)

Anterior temporal branches of PCA

2-27

Midsagittal view of the cerebral hemisphere and dien-

to serve medial regions of the frontal and parietal lobes, and the same

cephalon showing the locations and branching patterns of anterior and

relationship is maintained for the occipital and temporal lobes by

posterior cerebral arteries. The positions of gyri and sulci can be ex-

branches of the posterior cerebral artery. See Figures 8-1 (p. 240) and

trapolated from Figure 2-26 (facing page). Terminal branches of the

8-7 (p. 246) for comparable angiogram of anterior and posterior cere-

anterior cerebral artery arch laterally over the edge of the hemisphere

bral arteries.

Inferior sagittal sinus

Posterior vein of corpus callosum

Superior sagittal sinus

Internal occipital veins

Veins of the

caudate nucleus

Straight sinus

Septal veins

Sinus

confluens

Transverse

sinus

Superior

Anterior cerebral vein

cerebellar vein

Occipital

Basal vein

sinus

Great

Internal cerebral vein

cerebral vein

2-28

Midsagittal view of the cerebral hemisphere and dien-

(facing page). TV = Terminal vein (superior thalamostriate vein). See

cephalon that shows the locations and relationships of sinuses

Figures 8-2 (p. 241) and 8-11 (p. 250) for comparable angiogram (ve-

and the locations and general branching patterns of veins. The

nous phase) and MRV showing veins and sinuses.

position of gyri and sulci can be extrapolated from Figure

2-26

External Morphology of the Central Nervous System

Midbrain

quadrangular

lobe (AntLb)

lobule

Posterior

quadrangular

lobule

Posterior

Primary

superior

fissure

Superior semilunar

Hemisphere

lobule

Bpon

Vermis (Ver)

AntLb

SCP

Fourth ventricle

Basilar pons (Bpon)

Medulla (Med)

Flocculus (Fl)

Tonsil (Ton)

Biventer

lobule

Med

Gracile

lobule

Ton

Inferior

semilunar

PostLb

lobule

Hemisphere

Vermis (Ver)

Ver

Colliculi:

Superior

Cerebellar peduncles:

lobe (AntLb)

Inferior

Superior (SCP)

Middle (MCP)

Inferior

Primary fissure

AntLb

Horizontal

MCP

fissure

Flocculus (Fl)

Posterior

Tonsil (Ton)

lobe (PostLb)

Nodulus

Med

PostLb

2-31

Rostral (A, superior surface), caudal (B, inferior surface),

with cerebellar structures seen in axial MRIs at comparable levels (D,

and an inferior view (C, inferior aspect) of the cerebellum. The view

E). Structures seen on the inferior surface of the cerebellum, such as

in C shows the aspect of the cerebellum that is continuous into the

the tonsil (F), correlate closely with an axial MRI at a comparable level.

brainstem via cerebellar peduncles. The view in C correlates with su-

In G, note the appearance of the margin of the cerebellum, the general

perior surface of the brainstem (and middle superior cerebellar pe-

appearance and position of the lobes, and the obvious nature of the

duncles) as shown in Figure 2-34 on page 34.

middle cerebellar peduncle. All MRI images are T1-weighted.

Note that the superior view of the cerebellum (A) correlates closely

The Brain: Gross Views, Vasculature, and MRI

II,III

Midbrain (Mid)

Primary

fissure (PriFis)

PriFis

Basilar

pons (Bpon)

Mid

VII

Fourth

Bpon

VII

ventricle

(ForVen)

ForVen

Medulla

Med

VIII

(Med)

VIII

Posterolateral

fissure (PostLatFis)

II,III

PriFis

Mid

Bpon

VII

ForVen

Med

X IX

VIII

2-32

A median sagittal view of the cerebellum (A) showing its re-

Lobules I-V are the vermis parts of the anterior lobe; lobules VI-IX

lationships to the midbrain, pons, and medulla. This view of the cere-

are the vermis parts of the posterior lobe; and lobule X (the nodulus)

bellum also illustrates the two main fissures and the vermis portions of

is the vermis part of the flocculonodular lobe. Note the striking simi-

lobules I-X. Designation of these lobules follows the method devel-

larities between the gross specimen (A) and a median sagittal view of

oped by Larsell.

the cerebellum in a T1-weighted MRI (B) and a T2-weighted MRI (C).

Peduncles

Middle cerebellar

Superior cerebellar

Inferior colliculus

Trochlear nerve

Flocculus

Crus cerebri

Trigeminal nerve:

Sensory root

Motor root

Basilar pons

2-33

Lateral and slightly rostral view of the cerebellum and brain-

relative positions of, and distinction between, motor and sensory roots

stem with the middle and superior cerebellar peduncles exposed. Note

of the trigeminal nerve. See page 40, Figure 2-41D for an MRI show-

the relationship of the trochlear nerve to the inferior colliculus and the

ing the trochlear nerve.

External Morphology of the Central Nervous System

Internal cerebral vein

Superior colliculus (SC)

Inferior colliculus (IC)

Pineal

Frenulum

Pulvinar nuclear

complex (PuNu)

Medial

geniculate

body (MGB)

Brachium of

PulNu

superior

colliculus

MGB

LGB

Brachium of

Lateral

inferior

geniculate

colliculus

body (LGB)

Crus cerebri

Trochlear nerve

(cranial nerve IV)

Superior cerebellar

Anterior medullary velum

peduncle

Facial colliculus

Middle cerebellar

Sulcus limitans

peduncle

Superior fovea

Inferior cerebellar peduncle

Striae medullares of

(juxtarestiform body and

fourth ventricle

restiform body)

Lateral recess of

fourth ventricle

Vestibular area

Restiform body

Tela choroidea (cut edge)

Inferior fovea

Vagal trigone

Level of obex

Hypoglossal trigone

Tuberculum cuneatum (cuneate tubercle)

Tuberculum gracile

(gracile tubercle)

Posterolateral sulcus

Trigeminal tubercle (tuberculum cinerum)

Posterior intermediate sulcus

Cuneate fasciculus

Gracile fasciculus

Posterior median sulcus

2-34

Detailed dorsal view of the brainstem, with cerebellum re-

tuberculum cinereum is also called the trigeminal tubercle (tubercu-

moved, providing a clear view of the rhomboid fossa (and floor of the

lum trigeminale) because it is the surface representation of the spinal

fourth ventricle) and contiguous parts of the caudal diencephalon. The

trigeminal tract and its underlying nucleus. Figure 3-10 on page 61 also

dashed line on the left represents the position of the sulcus limitans and

shows a comparable view of the brainstem and the posterior portions

the area of the inferior cerebellar peduncle is shown on the right. The

of the diencephalon.

The Brain: Gross Views, Vasculature, and MRI

Vessels

Structures

Choroid plexus, third ventricle

Pineal

Habenula

Medial thalamus

Brachium of superior colliculus

Thalamogeniculate arteries

Superior

Lateral thalamus

colliculus

Pulvinar nucleus

Internal capsule

Choroid plexus,

lateral ventricle

Medial

Lateral geniculate body

and lateral

posterior choroidal arteries

Medial geniculate body

Quadrigeminal artery

Brachium of inferior colliculus

Superior cerebellar artery:

Crus cerebri

Medial branch

Trochlear nerve (IV)

Lateral branch

Inferior colliculus

Superior cerebellar peduncle

Anterior medullary velum

Facial colliculus

Vestibular area

Inferior cerebellar peduncle

Middle cerebellar peduncle

Choroid plexus, fourth ventricle

Hypoglossal trigone

Anterior inferior

Glossopharyngeal nerve (IX)

cerebellar artery

Vagal nerve (X)

Accessory nerve (XI)

Posterior inferior

cerebellar artery

Restiform body

Vagal trigone

Trigeminal tubercle (tuberculum cinereum)

Cuneate tubercle

Posterior spinal artery

Gracile tubercle

Gracile fasciculus

Cuneate fasciculus

2-35

Dorsal view of the brainstem and caudal diencephalon show-

tion to serving the medulla, branches of the posterior inferior cerebel-

ing the relationship of structures and some of the cranial nerves to ar-

lar artery also supply the choroid plexus of the fourth ventricle. The

teries. The vessels shown in this view have originated ventrally and

tuberculum cinereum is also called the trigeminal tubercle. See Figure

wrapped around the brainstem to gain their dorsal positions. In addi-

8-12 on p. 251 for blood supply of the choroid plexus.

The Brain: Gross Views, Vasculature, and MRI

Fornix

Choroid plexus, third ventricle

Optic tract

Posterior choroidal arteries

Thalamogeniculate artery

Lateral geniculate body

Dorsal thalamus

Posterior cerebral artery

Mammillary body

Medial geniculate body

Quadrigeminal artery

Superior colliculus

Posterior communicating

Crus cerebri

artery

Internal carotid artery

Brachium of inferior colliculus

Inferior colliculus

Oculomotor nerve

Superior cerebellar artery

Trochlear nerve

Trigeminal nerve

Motor root

Sensory root

Superior cerebellar peduncle

Anterior medullary velum

Basilar artery

Middle cerebellar peduncle

Anterior inferior

cerebellar artery

Vestibulocochlear nerve

Facial nerve

Labyrinthine artery

Posterior inferior

Abducens nerve

cerebellar artery

Glossopharyngeal nerve

Choroid plexus,

fourth ventricle

Vagus nerve

Hypoglossal nerve

Restiform body

Accessory nerve

Cuneate tubercle

Gracile tubercle

Posterior inferior cerebellar artery

Posterior spinal artery

Anterior spinal artery

Vertebral artery

2-38

Lateral view of the brainstem and thalamus, which shows the

shown as dashed lines. Arteries that distribute to dorsal structures orig-

relationship of structures and cranial nerves to arteries. The approxi-

inate from large ventral vessels. Compare with Figure 2-36 on the fac-

mate positions of the labyrinthine and posterior spinal arteries, when

ing page.

they originate from the basilar and vertebral arteries, respectively, are

External Morphology of the Central Nervous System

Optic nerve

Optic chiasm

Infundibulum

Optic tract

Crus cerebri

Mammillary

body

Interpeduncular

fossa

Optic nerve

Bulb of eye

Optic chiasm

Temporal lobe

Mammillary

body

Optic tract

Interpeduncular

fossa

Uncus

Midbrain

Crus cerebri

tegmentum

Dorsal thalamus

Frontal lobe

Interpeduncular

fossa

Optic nerve

Basilar pons

Bulb of eye

Anterior communicating

artery

Optic nerve

Optic chiasm

Anterior cerebral

Optic tract

artery, A₁ segment

Interpeduncular

fossa

Infundibulum

Midbrain

2-39

Inferior view of the hemisphere showing the optic nerve (II),

cerebral artery (D) is the most common site of supratentorial (carotid

chiasm, tract, and related structures (A). The MRIs of cranial nerve II

system) aneurysms. Rupture of aneurysms at this location is one of the

are shown in axial (B, T1-weighted; D, T2-weighted) and in oblique

more common causes of spontaneous subarachnoid hemorrhage. The

sagittal (C, T1-weighted) planes. Note the similarity between the ax-

proximity of these vessels to optic structures and the hypothalamus (D)

ial planes, especially (B), and the gross anatomical specimen. In addi-

explain the variety of visual and hypothalamic disorders experienced by

tion, note the relationship between the anterior cerebellar artery, an-

these patients. A lesion of the optic nerve results in blindness in that

terior communicating artery, and the structures around the optic

eye and loss of the afferent limb of the pupillary light reflex. Lesions

chiasm (D).

in, or caudal to, the optic chiasm result in deficits in the visual fields of

The anterior communicating artery or its junction with the anterior both eyes.

The Cranial Nerves

artery

Optic chiasm

Middle cerebral

artery

Posterior communicating

Posterior cerebral

artery

Oculomotor nerve

Basilar artery

Superior cerebellar

artery

Basilar pons

Optic tract

Posterior cerebral

Bulb of the eye

artery

Superior cerebellar

artery

Oculomotor nerve

Internal carotid

Oculomotor

artery

nerve

Oculomotor

Temporal lobe

nerve

Basilar pons

Uncus

(rostral portion)

Fourth ventricle

(rostral portion)

Corpus callosum

Dorsal thalamus

Frontal lobe

Superior colliculus

Interpeduncular

fossa

Inferior colliculus

Cerebellum

Optic chiasm

Basilar pons

Oculomotor nerve

2-40

Inferior view of the hemisphere showing the exiting fibers of

position of the oculomotor nerve in the interpeduncular fossa rostral

the oculomotor nerve (III), and their relationship to the posterior cere-

to the basilar pons and caudal to optic structures.

bral and superior cerebellar arteries (A). The MRIs of cranial nerve III

That portion of the posterior cerebral artery located between the

are shown in sagittal (B, T2-weighted; D, T1-weighted) and in axial

basilar artery and the posterior communicating artery (A) is the P₁ seg-

(C, T1-weighted) planes. Note the relationship of the exiting fibers of

ment. The most common site of aneurysms in the infratentorial area

the oculomotor nerve to the posterior cerebral and superior cerebel-

(vertebrobasilar system) is at the bifurcation of the basilar artery, also

lar arteries (A, B) and the characteristic appearance of the III nerve as

called the basilar tip. Patients with aneurysms at this location may pre-

it passes through the subarachnoid space toward the superior orbital fis-

sent with eye movement disorders and pupillary dilation due to dam-

sure (C). The sagittal section (D) is just off the midline and shows the

age to the root of the third nerve (A,B).

External Morphology of the Central Nervous System

Mammillary body

Interpeduncular

Lamina terminalis

fossa

Supraoptic recess

Cerebral aqueduct

Optic chiasm

Oculomotor nerve

Basilar pons

Infundibular recess

Posterior cerebral

Optic tract

artery

Superior cerebellar

artery

Optic nerve

Oculomotor nerve

Basilar pons

Posterior cerebral

Oculomotor nerve

artery

Posterior cerebral

Superior cerebellar

artery

Interpeduncular

Crus cerebri

fossa

Midbrain

Anterior lobe

of cerebellum

Anterior cerebral artery

Middle cerebral artery

Hypothalamus

Optic tract

Interpeduncular fossa

Mammillary body

Posterior cerebral artery

Crus cerebri

Trochlear nerve

Midbrain tegmentum

(in ambient cistern)

Fourth ventricle

(rostral portion)

2-41

A median sagittal view of the brainstem and diencephalon (A)

nerves of the midbrain. The third nerve exits via the interpeduncular

reveals the position of the oculomotor nerve (III) in relation to adjacent

fossa to innervate four major extraocular muscles (see Fig. 7-15 on

structures. The MRI in B and C show the position of the oculomotor

page 201) and, through the ciliary ganglion, the sphincter pupillae

nerve in sagittal (B, T1-weighted) and in axial (C, T2-weighted) planes.

muscles. Damage to the oculomotor nerve may result in paralysis of

Note the relationship of the oculomotor nerve to the adjacent posterior

most eye movement, a dilated pupil, and loss of the efferent limb of

cerebral and superior cerebellar arteries (B, C). Also compare these im-

the pupillary light reflex, all in the ipsilateral eye. The fourth nerve is

ages with that of figure 2-40B on page 39. In D (T2-weighted), the

unique in that it is the only cranial nerve to exit the posterior (dorsal)

trochlear nerve is seen passing through the ambient cistern around the

aspect of the brainstem and is the only cranial nerve motor nucleus to

lateral aspect of the midbrain (compare with Fig. 2-32 on page 32).

innervate, exclusively, a muscle on the contralateral side of the mid-

The oculomotor (III) and trochlear (IV) nerves are the cranial

brain.

The Cranial Nerves

Basilar pons

Trigeminal nerve

Abducens nerve

Facial nerve

Flocculus

Vestibulocochlear

Pyramid

nerve

Internal carotid artery

Temporal lobe

Trigeminal nerve

Basilar artery

Middle cerebellar

Trigeminal nerve

peduncle

Basilar pons

Fourth ventricle

Pontine tegmentum

Cerebellum

Temporal lobe

Trigeminal

ganglion

Basilar artery

Trigeminal nerve

Superior cerebellar

artery

Tegmentum

of pons

Basilar pons

Fourth ventricle

Anterior lobe

of cerebellum

Third ventricle

Midbrain

Crus cerebri

tegmentum

Interpeduncular

Root of trigeminal

fossa

nerve

Sensory root of the

trigeminal nerve

Basilar pons

Pyramid

2-42

The trigeminal nerve (V) is the largest of the cranial nerve

in the coronal plane (D, E). In addition, the MRI in C clearly illustrates

roots exiting the brainstem (A). It exits at an intermediate position on

the position of the trigeminal ganglion in the middle cranial fossa.

the lateral aspect of the pons roughly in line with cranial nerves VII, IX,

Trigeminal neuralgia (tic douloureux) is a lancinating paroxysmal

and X. The fifth nerve, and these latter three, are mixed nerves in that

pain within the V₂-V₃ territories frequently triggered by stimuli

they have motor and sensory components. The trigeminal nerve is

around the corner of the mouth. The causes are probably multiple and

shown in axial MRI (B, T1-weighted; C, T2-weighted) and in coronal

may include neurovascular compression by the superior cerebellar

planes (D, E, both T1-weighted images). Note the characteristic ap-

artery (see the apposition of this vessel to the nerve root in C), multi-

pearance of the root of the trigeminal nerve as it traverses the sub-

ple sclerosis, tumors, and ephaptic transmission within the nerve or

arachnoid space (B and C), the origin of the trigeminal nerve, and the

ganglion.

position of the sensory root of the nerve at the lateral aspect of the pons

External Morphology of the Central Nervous System

Abducens nerve

Facial nerve

Vestibulocochlear

nerve

Vestibulocochlear

nerve

Facial nerve

Glossopharyngeal

nerve

Pyramid

Vagus nerve

Olivary eminence

Hypoglossal nerve

Basilar artery

Cochlea

Abducens nerve

Semicircular canals

Pons-medulla junction

Vestibulocochlear

nerve

Lateral recess of

fourth ventricle

Facial nerve

Fourth ventricle

Tonsil of cerebellum

Abducens nerve

Cochlea

Cochlear portion of

VIIIth nerve (CPVIII)

Semicircular canals

VPVIII

Semicircular canals

CPVIII

Vestibular portion of

VIIIth nerve (VPVIII)

Fourth ventricle

Basilar pons

Pontine tegmentum

Cerebellum

Cochlear portion of

VIIIth nerve

Anterior inferior

cerebellar artery

Cochlea

Semicircular canals

Vestibular portion of

Cerebellar vermis

VIIIth nerve

Cerebellar

tonsil

hemisphere

2-43

The cranial nerves at the pons medulla junction are the ab-

inferior cerebellar artery also enters the internal acoustic

ducens (VI), the facial (VII), and the vestibulocochlear (VIII) (A). The

meatus.

facial and vestibulocochlear nerves both enter the internal acoustic

The so-called acoustic neuroma, a tumor associated with the eighth

meatus, the facial nerve distributing eventually to the face through the

nerve, is actually a vestibular schwannoma since it arises from the

stylomastoid foramen, and the vestibulocochlear nerve to structures

neurilemma sheath of the vestibular root. Most patients with this tu-

of the inner ear. MRI in the axial plane, B, C, D, (all T2-weighted im-

mor have hearing loss, tinnitus and equilibrium problems, or vertigo.

ages) show the relationships of the vestibulocochlear root and the fa-

As the tumor enlarges (to more than about 2 cm) it may cause facial

cial nerve to the internal acoustic meatus. Also notice the character-

weakness (seventh root), numbness (fifth root), or abnormal corneal

istic appearance of the cochlea (B, C) and the semicircular canals (C).

reflex (fifth or seventh). Treatment is usually by surgery, radiation

In addition to these two cranial nerves, the labyrinthine branch of the

therapy, or a combination thereof.

The Cranial Nerves

Facial nerve

Abducens nerve

Vestibulocochlear

nerve

Glossopharyngeal

Olivary eminence

nerve

Vagus nerve

Postolivary sulcus

Preolivary sulcus

Hypoglossal nerve

Preolivary sulcus

Pyramid

Retroolivary sulcus

(postolivary sulcus)

Olive (inferior)

Glossopharyngeal

nerve

Flocculus

Restiform body

Fourth ventricle

Tonsil of cerebellum

Cerebellum

Pyramid

Olive (inferior)

Vagus nerve

Retroolivary sulcus

Fourth ventricle

Tonsil of cerebellum

Cerebellum

Pyramid

Olivary eminence

Vagus nerve

Postolivary sulcus

Restiform body

Vagus nerve

Fourth ventricle

Tonsil of cerebellum

2-44

The glossopharyngeal (IX) and vagus (X) nerves (A) exit the

cle is smaller. The ninth and tenth cranial nerves and the spinal portion

lateral aspect of the medulla via the postolivary sulcus; the ninth nerve

of the accessory nerve (XI) exit the skull via the jugular foramen.

exits rostral to the row of rootlets comprising the tenth nerve (A).

Glossopharyngeal neuralgia is a lancinating pain originating from

These nerves are generally in line with the exits of the facial and

the territories served by the ninth and tenth nerves at the base of the

trigeminal nerves; all of these are mixed nerves. The exit of the glos-

tongue and throat. Trigger events may include chewing and swallow-

sopharyngeal nerve (A, B) is close to the pons-medulla junction and

ing. Lesions of nerves passing through the jugular foramen (IX, X, XI)

correlates with the corresponding shape (more rectangular) of the

may result in loss of the gag reflex (motor limb via ninth nerve), and

medulla. The vagus nerve exits at a slightly more caudal position (A,

drooping of the ipsilateral shoulder accompanied by an inability to turn

C, D); the shape of the medulla is more square and the fourth ventri-

the head to the opposite side against resistance (eleventh nerve).

External Morphology of the Central Nervous System

Comparison of Cerebral versus Spinal Meninges

CEREBRAL

SPINAL

Dura

• adherent to inner table of skull (no epidural space)

• separated from vertebrae by epidural space

• composed of two fused layers (periosteal and meningeal),

• composed of one layer (spinal dura only; vertebrae

which split to form sinuses

have their own periosteum)

Arachnoid (outer part of leptomeninges)

• attached to dura in living condition (no subdural space)

• attached to dura in living condition (no subdural

space)

• arachnoid villi (in superior sagittal sinus)

• no arachnoid villi

• arachnoid trabeculae

• few or no arachnoid trabeculae but larger arachnoid septae

• subarachnoid space with many cisterns

• subarachnoid space with one cistern

Pia (inner part of leptomeninges)

• intimately adherent to surface of brain

• intimately adherent to surface of cord

• no pial specializations

• specializations in the form of denticulate ligaments,

filum terminale, and linea splendens

• follows vessels as they pierce the cerebral cortex

• follows vessels as they pierce the cord

Meningitis, Meningeal, Hemorrhages, Meningioma

A wide variety of disease processes and lesions may involve the

commonly seen in younger patients, are usually detected immediately

meninges; only a few examples are mentioned here.

or within a few hours after the precipitating incident. Chronic subdural

Bacterial infections of the meninges (bacterial meningitis) are

hematomas, usually seen in the elderly, are frequently of unknown ori-

commonly called leptomeningitis because the causative organisms are

gin; may take days or weeks to become symptomatic; and cause a pro-

usually found in the subarachnoid space and involve the pia and arach-

gressive change in mental status of the patient. This lesion appears

noid. The organism seen in about one-half of adult cases is Streptococcus

“long and thin,” compared to an epidural hematoma, follows the sur-

pneumoniae, while in neonates and children up to about 1 year it is Es-

face of the brain, and may extend for considerable distances (see Fig.

cherichia coli. The patient becomes acutely ill (i.e., confusion, fever, stiff

2-48 on p. 48 and Fig. 2-51 on p. 51). Treatment is surgical evacua-

neck, stupor), may have generalized or focal signs/symptoms, and, if

tion (for larger or acute lesions) or close monitoring for small, asymp-

not treated rapidly, will likely die. Treatment is with appropriate an-

tomatic, or chronic lesions.

tibiotics. Patients with viral meningitis may become ill over a period

The most common cause of subarachnoid hemorrhage is trauma.

of several days, experience headache, confusion, and fever, but, with

In approximately 80% of patients with spontaneous (nontrau-

supportive care, will recover after an acute phase of approximately 1-2

matic) subarachnoid hemorrhage, the precipitating event is rupture

weeks. These patients usually recover with no permanent deficits.

of an intracranial aneurysm. Symptomatic bleeding from an arteriove-

The most common cause of an epidural (extradural) hematoma

nous malformation occurs in approximately 5% of cases. Blood collects

is a skull fracture that results in a laceration of a major dural vessel, such

in, and percolates through, the subarachnoid space and cisterns (see

as the middle meningeal artery. In approximately 15% of cases, bleed-

Fig. 2-51 on page 51). Sometimes, the deficits seen (assuming the pa-

ing may come from a venous sinus. The extravasated blood dissects the

tient is not in coma) may be a clue as to location, especially if cranial

dura mater off the inner table of the skull; there is no preexisting (ex-

nerves are nearby. Onset is sudden; the patient complains of an excru-

tradural) space for the blood to enter. These lesions are frequently

ciating headache and may remain conscious, become lethargic and dis-

large, lens (lenticular) shaped, may appear loculated, and are “short

oriented, or may be comatose. Treatment of an aneurysm is to surgi-

and thick” compared to subdural hematomas (see Fig. 2-48 on page

cally occlude it (by clip or coil), if possible, and to protect against the

48). The patient may lapse into a coma and, if the lesion is left un-

development of vasospasm. During surgery, some blood in the sub-

treated, death may result. In some cases, the patient may initially be

arachnoid space and cisterns may be removed.

unconscious followed by a lucid interval (the patient is wide awake),

Tumors of the meninges (meningiomas) are classified in different

then subsequently deteriorate rapidly and die; this is called “talk and

ways but they usually arise from arachnoid cap/stem cells (a small

die.” Treatment of choice for large lesions is surgical removal of the

number are dural in origin) around the villi or at places where vessels

clot and coagulation of the damaged vessel.

or cranial nerves penetrate the dura-arachnoid. These tumors grow

Tearing of bridging veins (veins passing from the brain outward

slowly (symptoms may develop almost imperceptibly over years), are

through the arachnoid and dura), usually the result of trauma, is a com-

histologically benign, may result in hyperostosis of the overlying skull,

mon cause of subdural hematoma. This designation is somewhat a

and frequently contain calcifications. In decreasing order, menin-

misnomer because the extravasated blood actually dissects through a

giomas are found in the following locations: parasagittal area

falx

specialized, yet structurally weak, cell layer at the dura-arachnoid in-

(together 29%), convexity 15%, sella 13%, sphenoid ridge 12%, and

terface; this is the dural border cell layer. There is no preexisting “sub-

olfactory groove 10%. Treatment is primarily by surgical removal, al-

dural space” in the normal brain. Acute subdural hematomas, more

though some meningiomas are treated by radiotherapy.

The Meninges, Cisterns, and Meningeal and Cisternal Hemorrhages

Subdural

hemorrhage

Lamina terminalis

cistern

Supraoptic recess

Sylvian

Interpeduncular

cistern

Crural

cistern

Temporal

horn

Blood on

insular cortex

Midbrain

Ambient

Quadrigeminal

cistern

Lamina terminalis

Third

cistern

ventricle

Sylvian

Blood on

cistern

insula

Interpeduncular

cistern

Crural

cistern

Ambient

Cerebellum

cistern

Blood on tentorium

Rostral part

cerebelli

of fourth

ventricle

2-51

Blood in the subarachnoid space and cisterns. In these CT ex-

blood on the cortex of the insula. In C, the blood is located around the

amples, blood occupies the subarachnoid space and cisterns, outlining

midbrain (crural and ambient cisterns), extends into the Sylvian cis-

these areas in white. Consequently, the shape of the cisterns is indi-

tern, and into the cistern of the lamina terminalis. The sharp interface

cated by the configuration of the white area, the white area represent-

between the lamina terminalis cistern (containing blood) and the third

ing blood.

ventricle (devoid of blood) represents the position of the lamina ter-

Around the base of the brain (A), it is easy to identify the cisterns

minalis. In D, blood is located in cisterns around the pons but avoids

related to the midbrain, the supraoptic recess which is devoid of blood,

the rostral part of the fourth ventricle. Compare these images with the

and blood extending laterally into the Sylvian cistern. In some cases

locations of some of the comparable cisterns as seen in Figure 2-50 on

(B), subdural hemorrhage may penetrate the arachnoid membrane and

the facing page. Images A-D are CT.

result in blood infiltrating between gyri, such as this example with

External Morphology of the Central Nervous System

Massa intermedia

Body of lateral

Pineal recess

ventricle

Third ventricle

Suprapineal recess

Anterior horn of

Posterior commissure

lateral ventricle

Pineal

Interventricular

Atrium of lateral ventricle

foramen

(and glomus choroideum)

Posterior horn of

Anterior commissure

lateral ventricle

Tectum

Lamina terminalis

Cerebral aqueduct

Infundibular recess

Supraoptic recess

Fourth ventricle

Optic chiasm

Infundibulum

Lateral recess of fourth ventricle

Mammillary body

Foramen of

Amygdaloid nuclear complex

Luschka

Inferior horn of lateral ventricle

Dorsal cerebellomedullary

cistern (cisterna magna)

Bordering Structures

Ventricular Space

Genu of corpus callosum

Anterior horn of lateral ventricle

Head of caudate nucleus

Septum pellucidum

Body of lateral ventricle

(ventral to body of corpus callosum)

Body of caudate nucleus

Third ventricle

Fornix

Suprapineal recess

Amygdaloid nuclear complex

Inferior horn of

lateral ventricle

Tail of caudate nucleus

Hippocampal formation

Cerebral aqueduct

Splenium of

corpus callosum

Atrium of lateral ventricle

(contains glomus choroideum)

Optic radiations

Tapetum

Lateral recess of

fourth ventricle

Fourth ventricle

Posterior horn of lateral ventricle

2-52

Lateral (above) and dorsal (below) views of the ventricles and

colors are continued in Figure 2-53 on the facing page. Note the rela-

the choroid plexus. The dashed lines show the approximate positions

tionships between the choroid plexus and various parts of the ventric-

of some of the important structures that border on the ventricular

ular system. The large expanded portion of the choroid plexus found

space. The choroid plexus is shown in red and structures bordering on

in the area of the atrium is the glomus (glomus choroideum). See Fig-

the various portions of the ventricular spaces are color-coded; these

ure 8-12 on p. 251 for details of blood supply to the choroid plexus.

The Ventricles and Ventricular Hemorrhage

Corpus callosum

Caudate nucleus

(body)

Corpus callosum

(body)

Caudate nucleus (body)

Anterior horn of

lateral ventricle

Stria terminalis

Septum

pellucidum

Corpus callosum (body)

Septum

pellucidum

Fornix (F)

Body of lateral

Caudate nucleus

ventricle

Body of lateral

(head)

ventricle

Choroid plexus (CP)

Interventricular

Corpus callosum

foramen

(rostrum)

Fornix

commissure

Third ventricle

Gyrus rectus

Dorsal thalamus

Hypothalamus

Massa intermedia

Optic chiasm

Mammillary body

Hypothalamus

Caudate nucleus

Fornix

Dorsal thalamus

Third ventricle

Amygdaloid nuclear

complex

Optic tract

Inferior horn of

lateral ventricle

Body of lateral

ventricle

Corpus callosum

Pulvinar

Optic radiations

Tapetum

Pineal

Cerebral aqueduct

Inferior horn of

lateral ventricle

Hippocampal formation

Corpus callosum

(splenium)

Caudate nucleus (tail)

Atrium of lateral

Calcarine

ventricle

sulcus

Hippocampal formation

Calcar avis

Posterior horn of

lateral ventricle

2-53

Lateral view of the ventricular system and corresponding

and the majority of structures labeled have some direct relevance to the

semidiagrammatic cross-sectional representations from rostral (A) to

ventricular space at that particular level. The color-coding corresponds

caudal (G) identifying specific structures that border on the ventricu-

to that shown in Figure 2-52 on the facing page.

lar space. In the cross-sections, the ventricle is outlined by a heavy line,

Internal Morphology of the Brain in Slices and MRI

Anterior horn of lateral

Genu of corpus callosum

ventricle (AHLatVen)

Septum pellucidum

Stria terminalis and

terminal vein

Head of caudate nucleus (HCaNu)

Genu of internal

Column of fornix (ColFor)

capsule (GIntCap)

Anterior limb of

Anterior nucleus of thalamus

internal capsule (ALIntCap)

Ventral anterior nucleus

Putamen (Put)

of thalamus

Choroid plexus in third ventricle

Globus pallidus (GP)

Insula (In)

Claustrum

Third ventricle (ThrVen)

Posterior limb of internal

capsule (PLIntCap)

Internal medullary lamina

Dorsomedial nucleus

Ventral lateral nucleus

of thalamus (DMNu)

of thalamus

Habenular nucleus

Centromedian nucleus

(Hab)

of thalamus

Ventral posterolateral

nucleus of thalamus

Retrolenticular limb of

internal capsule (RLIntCap)

Tail of caudate nucleus

Fimbria of hippocampus

Pulvinar (Pul)

Hippocampal formation (Hip)

Atrium of lateral

ventricle (ALatVen)

Crus of fornix

Optic radiations

Tapetum

Splenium of corpus callosum (SpCorCl)

Posterior horn of lateral ventricle (PHLatVen)

ALIntCap

AHLatVen

HCaNu

ALIntCap

GIntCap

Put

GIntCap

PLIntCapr

ColFor

PLIntCap

ThrVen

Lateral

thalamic

Lateral

nuclei

thalamic

nuclei

DMNu

RLIntCap

ALatVen

RLIntCap

Pul

Hab

PHLatVen

Hip

ThrVen

SpCorCl

4-12

Ventral surface of an axial section of brain through the genu of

structures identified in the brain slice. The arrowheads in the brain slice

the corpus callosum, head of caudate nucleus, centromedian nucleus, and dor-

and in the MRIs are pointing to the mammillothalamic tract. The ter-

sal portions of the pulvinar. The two MRI images (inversion recovery—

minal vein is also called the superior thalamostriate vein.

left; T2-weighted—right) are at the same plane and show many of the

Axial Brain Slice—MRI Correlation

Genu of corpus callosum

Anterior commissure (AC)

Subcallosal gyri

Head of caudate nucleus (HCaNu)

Anterior limb of internal

capsule (ALIntCap)

Column of fornix (ColFor)

Third ventricle

Putamen (Put)

Mammillothalamic tract (MtTr)

Globus pallidus (GP)

External capsule

Insula (In)

Claustrum

Posterior limb of internal

Extreme capsule

capsule (PLIntCap)

Ventral posterior

thalamic nuclei

Subthalamic nucleus

Brachium of superior

colliculus

Red nucleus (RNu)

Pulvinar

Lateral geniculate

nucleus (LGNu)

Tail of caudate nucleus

Retrolenticular limb of

internal capsule

Tapetum (Tap)

Fimbria of hippocampus

Optic radiation (OpRad)

Hippocampal formation (Hip)

Atrium of lateral ventricle

(ALatVen)

Medial geniculate

nucleus (MGNu)

Posterior horn of lateral ventricle

(PHLatVen)

Pineal

Superior colliculus (SC)

Splenium of corpus callosum (SpCorCl)

HCaNu

ColFor

ALIntCap

ColFor

Put

MtTr

PLIntCap

RNu

LGNu

Massa

Lateral

intermed.

MGNu

thalamic

nuclei

Pul

Tap

Hip

Dorsomedial

nucleus

ALatVen

Crus of

fornix

PHLatVen

OpRad

SpCorCl

4-13

Ventral surface of an axial section of brain through the anterior

can be discerned on the right side of the brain. The MRI images (both

commissure, column of fornix, medial and lateral geniculate nuclei, and supe-

T2-weighted) are at approximately the same plane and show many of

rior colliculus. The medial and lateral segments of the globus pallidus are vis-

the structures identified in the brain slice.

ible on the slice. The lateral and medial segments of the globus pallidus

CHAPTER

Internal Morphology of the Spinal Cord

and Brain in Stained Sections

Basic concepts that are essential when one is initially learning how

and the lateral corticospinal tract (grey). In the brainstem, these

to diagnose the neurologically impaired patient include 1) an un-

spinal tracts are joined by the spinal trigeminal tract and ventral

derstanding of cranial nerve nuclei and 2) how these structures re-

trigeminothalamic fibers (both are light green). The long tracts are

late to long tracts. The importance of these relationships is clearly

color-coded on one side only, to emphasize 1) laterality of function

seen in the combinations of deficits that generally characterize le-

and dysfunction, 2) points at which fibers in these tracts may de-

sions at different levels of the neuraxis. First, deficits of only the

cussate, and 3) the relationship of these tracts to cranial nerves.

body that may present as motor or sensory losses (long tracts) on

A color key appears on each page. This key identifies the var-

the same, or opposite, sides are indicative of spinal cord lesions

ious tracts and nuclei by their color and specifies the function of

(e.g., Brown-Sequard syndrome). Spinal cord injuries character-

each structure on each page. This approach not only emphasizes

istically have motor and sensory levels; these are the lowest functional

anatomical and clinical concepts, but also lends itself to a variety

levels remaining in the compromised patient. Second, cranial

of instructional settings.

nerve deficits (on one side of the head) in combination with long

Correlation of MRI and CT with Spinal Cord and

tract signs (on the opposite side of the body) characterize lesions

Brainstem: As one is learning basic anatomical concepts it is

in the brainstem (e.g., lateral medullary or Weber syndromes).

essential to consider how this information may be used in the

These patterns of loss are frequently called alternating or crossed

clinical environment. To this end, MRI (T1- and T2-weighted)

deficits. In these examples cranial nerve signs are better localizing

and CT (myelogram/cisternogram) images are introduced into

signs than are long tract signs. A localizing sign can be defined as an

the spinal cord and brainstem sections of this chapter (see also

objective neurologic abnormality that correlates with a lesion (or

Chapter 1). To show the relationship between basic anatomy and

lesions) at a specific neuroanatomical location (or locations).

how MRI and CT are viewed, a series of self-explanatory illus-

Third, motor and sensory deficits on the same side of the head and

trations are provided on each set of facing pages in these sections.

body are usually indicative of a lesion in the forebrain.

This continuum of visual information consists of (1) a small ver-

Color Coded Cranial Nerve Nuclei and Long Tracts:

sion of the colorized line drawing in an Anatomical Orientation,

Cranial nerve nuclei are coded by their function: pink, sensory;

(2) a top-to-bottom flip of this illustration that brings it into a

red, motor. These structures are colored bilaterally to make it easy

Clinical Orientation, and (3) a CT (spinal cord) or MRI and CT

to correlate cranial nerve and long tract function on both sides of

(brainstem) that follows this clinically oriented image. Every ef-

the midline. For example, one can easily correlate damage to the

fort is made to identify and use MRI and CT that correlate, as

hypoglossal nerve root and the adjacent corticospinal fibers on one

closely as possible, with their corresponding line drawing and

side while comparing this pattern with the clinical picture of a lat-

stained section. This approach recognizes and retains the

eral medullary syndrome on the other side.

strength of the anatomical approach, introduces essential clinical

Long tracts are color-coded beginning at the most caudal spinal

concepts while at the same time allowing the user to customize

cord levels (e.g., see Figures 5-1 and 5-2), with these colors ex-

the material to suit a range of educational applications.

tending into the dorsal thalamus (see Figure 5-30) and the posterior

limb of the internal capsule (see Figures 5-31 and 5-32). The col-

orized spinal tracts are the fasciculus gracilis (dark blue), the fasci-

*The dark and light blue colors represent information originating from lower

culus cuneatus (light blue)*, the anterolateral system (dark green),

and upper portions of the body, respectively.

CHAPTER

Internal Morphology of the Brain in Stained

Sections: Axial-Sagittal Correlations with MRI

Although the general organization of Chapter 6 has been de-

in this chapter gives the reader an opportunity to compare in-

scribed in Chapter 1 (the reader may wish to refer back to this

ternal brain anatomy, as seen in stained sections, with those

section), it is appropriate to reiterate its unique features at this

structures as visualized in clinical images generated in the same

point. Each set of facing pages has photographs of an axial stained

plane. Even a general comparison reveals that many features, as

section (left-hand page) and a sagittal stained section (right-hand

seen in the stained section, can be readily identified in the adja-

page). In addition to individually labeled structures, a heavy line

cent MRI.

appears on each photograph. This prominent line on the axial

This chapter is also organized so that one can view structures in

section represents the approximate plane of the sagittal section

either the axial or the sagittal plane only. Axial photographs appear

located on the facing page. On the sagittal section this line signi-

on left-hand pages and are sequenced from dorsal to ventral (odd-

fies the approximate plane of the corresponding axial section.

numbered Figures 6-1 through 6-9), while sagittal photographs are

The reader can identify features in each photograph and then, us-

on the right-hand pages and progress from medial to lateral (even-

ing this line as a reference point, visualize structures that are lo-

numbered Figures 6-2 through 6-10). Consequently, the user can

cated either above or below that plane (axial to sagittal compar-

identify and follow structures through an axial series by simply flip-

ison) or medial or lateral to that plane

(sagittal to axial

ping through the left-hand pages or through a sagittal series by flip-

comparison). This method of presentation provides a format for

ping through the right-hand pages. The inherent flexibility in this

reconstructing and understanding three-dimensional relation-

chapter should prove useful in a wide variety of instructional/

ships within the central nervous system.

learning situations. The drawings shown in the following illustrate

The magnetic resonance image (MRI) placed on every page the axial and sagittal planes of the photographs in this chapter.

Fig. 6-6

Fig. 6-4

Fig. 6-8

Fig. 6-2

Fig. 6-10

Axial Planes

Fig. 6-1

Fig. 6-3

Fig. 6-5

Sagittal

Fig. 6-7

Planes

Fig. 6-9

Axial-Sagittal Correlations

163

AntNu

For,B

LDNu

CorCl,Spl

CorCl,G

DMNu

PrTecNu

SMT

Hab

PoCom

RNu

For,Col

HyTh

TroNr

MtTr

MLF

OcNr

FNu

OpNr

SCP,Dec

AbdNu

NuGr

HyNu

LCSp

6-2

Sagittal section through the column of the fornix, anterior thalamic

represents the approximate plane of the axial section shown in Figure

nucleus, red nucleus, and medial portions of the pons (abducens nucleus),

6-1 (facing page). Many of the structures labeled in this photograph can

cerebellum (fastigial nucleus), and medulla (nucleus gracilis). The heavy line

be clearly identified in the adjacent T1-weighted MRI.

Abbreviations

AbdNu Abducens nucleus

MB Mammillary body

AC Anterior commissure

ML Medial lemniscus

AntNu Anterior nucleus of thalamus

MLF Medial longitudinal fasciculus

BP Basilar pons

MtTr Mammillothalamic tract

CorCI,G Corpus callosum, genu

NuGr Nucleus gracilis

CorCI,Spl Corpus callosum, splenium

OcNr Oculomotor nerve

DMNu Dorsomedial nucleus of thalamus

OpNr Optic nerve

FNu Fastigial nucleus (medial cerebellar nucleus)

PO Principal olivary nucleus

For,B Fornix, body

PoCom Posterior commissure

For,Col Fornix, column

PrTecNu Pretectal nuclei

Hab Habenular nuclei

Py Pyramid

HyNu Hypoglossal nucleus

RNu Red nucleus

HyTh Hypothalamus

SC Superior colliculus

IC Inferior colliculus

SCP,Dec Superior cerebellar peduncle, decussation

LCsp Lateral corticospinal tract

SMT Stria medullaris thalami

LDNu Lateral dorsal nucleus

TroNr Trochlear nerve

Axial-Sagittal Correlations

165

LatVen,AH

MtTr

CorCl,B

LDNu

For,B

CorCl, Spl

AntNu

DMNu

PulNu

ThFas

RNu

Hyth

LenFas

AnLen

OpTr

SCP

OlfTr

ForVen

NuGr

FacNu

SolNu & Tr

NuCu

6-4

Sagittal section through anterior and ventral anterior thalamic nu-

sents the approximate plane of the axial section shown in Figure 6-3

clei, red nucleus and central areas of the pons, cerebellum (and superior pe-

(facing page). Many of the structures labeled in this photograph can be

duncle), and medulla (solitary nuclei and tract). Note the position of the

clearly identified in the adjacent T1-weighted MRI.

facial motor nucleus at the pons-medulla junction. The heavy line repre-

Abbreviations

Anterior commissure

LDNu Lateral dorsal nucleus

AnLen

Ansa lenticularis

ML Medial lemniscus

AntNu

Anterior nucleus of thalamus

MtTr Mammillothalamic tract

Basilar pons

NuCu Nucleus cuneatus

Crus cerebri

NuGr Nucleus gracilis

CM Centromedian nucleus

OlfTr Olfactory tract

CorCl,B

Corpus callosum, body

OpTr Optic tract

CorCl, Spl Corpus callosum, splenium

PO Principal olivary nucleus

DMNu Dorsomedial nucleus of thalamus

PulNu Pulvinar nuclear complex

FacNu

Facial nucleus

RNu Red nucleus

For,B

Fornix, body

SC Superior colliculus

ForVen

Fourth ventricle

SCP Superior cerebellar peduncle (brachium

H Prerubral field

conjunctivum)

HyTh

Hypothalamus

SN Substantia nigra

Inferior colliculus

SolNu&Tr Solitary nuclei and tract

LatVen,AH Lateral ventricle, anterior horn

ThFas Thalamic fasciculus

LenFas

Lenticular fasciculus

VA Ventral anterior nucleus of thalamus

Axial-Sagittal Correlations

167

CorCl,G

LDNu

CorCl,Spl

DMNu

PulNu

CaNu,H

RNu

SCP

ENu

OpTr

AnLen

SOpNu

LenFas

CSNu

TriMoNu

FacNr

OCblF

NuCu

6-6

Sagittal section through central regions of the diencephalon (cen-

heavy line represents the approximate plane of the axial section shown

tromedian nucleus) and midbrain (red nucleus), and through lateral areas of

in Figure 6-5 (facing page). Many of the structures labeled in this pho-

the pons (trigeminal motor nucleus) and medulla (nucleus cuneatus). The

tograph can be clearly identified in the adjacent T1-weighted MRI.

Abbreviations

AC Anterior commissure

LL Lateral lemniscus

AnLen Ansa lenticularis

ML Medial lemniscus

CaNu,H Caudate nucleus, head

NuCu Nucleus cuneatus

CC Crus cerebri

OCblF Olivocerebellar fibers

CM Centromedian nucleus of thalamus

OpTr Optic tract

CorCl,G Corpus callosum, genu

PulNu Pulvinar nuclear complex

CorCl,Spl Corpus callosum, splenium

RNu Red nucleus

CSNu Chief (prinicipal) sensory nucleus of trigeminal nerve

SC Superior colliculus

DMNU Dorsomedial nucleus of thalamus

SCP Superior cerebellar peduncle (brachium con-

ENu Emboliform nucleus (anterior interposed cerebellar nucleus)

junctivum)

FacNr Facial nerve

SN Substantia nigra

H Field of Forel (prerubral field)

SOpNu Supraoptic nucleus

IC Inferior colliculus

TriMoNu Trigeminal motor nucleus

LenFas Lenticular fasciculus

VA Ventral anterior nucleus of thalamus

LDNu Lateral dorsal nucleus of thalamus

VL Ventral lateral nucleus of thalamus

CHAPTER

Synopsis of Functional Components,

Tracts, Pathways, and Systems

The study of regional neurobiology (brain structures in gross spec-

the CD that comes with this atlas; these are taken from the cur-

imens, in brain slices, in stained sections, and in MRI and CT) is

rent edition of Stedman’s Medical Dictionary. In this respect, the

the basis for the study of systems neurobiology (tracts, pathways,

full definitions are actually available in this book. Researching the

cranial nerves and their functions), which, in turn, is the basis for

full definition of a clinical term or phrase is a powerful and ef-

understanding and diagnosing the neurologically impaired pa-

fective learning tool. Also, each clinical term or phrase is avail-

tient. Building on the concepts learned in earlier chapters on ex-

able in any standard medical dictionary or comprehensive neu-

ternal and internal brain anatomy in specimens and in MRI and

rology text.

CT, on brain vascular patterns, and on the relationships of cra-

The layout of the drawings in this chapter clearly shows the

nial nerves with long tracts, this chapter explores systems neurobi-

laterality of the tract/pathway. That is, the relationship between

ology with a particular emphasis on clinical correlations.

the location of the cell of origin and the termination of the fibers

The format of each set of facing pages is designed to summa-

making up a tract/pathway or the projections of cranial nerve

rize, accurately and consisely, the relationships of a given tract

nuclei. This information is absolutely essential to understanding the po-

or pathway. This includes, but is not limited to, 1) the location

sition of a lesion and correlating this fact with the deficits seen in the

of the cells of origin for a given tract/pathway, 2) its entire

neurologically compromised patient. For example, is the deficit on

course throughout the neuraxis and cerebrum, 3) the location of

the same side as the lesion (ipsilateral), on the opposite side (con-

the decussation of these fibers, if applicable, 4) the neurotrans-

tralateral), or on both sides (bilateral)? The concept of laterality

mitters associated with the neurons comprising the tract/pathway,

is usually expressed as “right,” “left,” or “bilateral” in reference

5) a brief review of its blood supply, and 6) a summary of a num-

to the side of the deficit(s) when written on the patient’s chart.

ber of deficits seen as a result of lesions at various points in the

This chapter is designed to maximize the correlation between

tract/pathway. The structure of an atlas does not allow a detailed

structure and function, to provide a range of clinical examples

definition of each clinical term on the printed page. However,

for each tract/pathway, and to help the user develop a knowl-

the full definition of each clinical term or phrase is available on

edge base that can be easily integrated into the clinical setting.

174

Synopsis of Functional Components, Tracts, Pathways, and Systems

SSA

SVA

GVA

posterior

GSA

GVA

medial

lateral

GVE

GSE

GSA

GVA

GVE

GSE

7-1

A semidiagrammatic summary of the positions of functional

In the brainstem, however, there is a slight transposition of the SVE

components as seen in the developing neural tube (left) and in the

and GSA functional components. Embryologically, SVE cell groups ap-

spinal cord and brainstem of the adult (right). In the neural tube, the

pear between those associated with GSE and GVE components. As de-

alar plate and its associated GSA and GVA components are posterior

velopment progresses, however, SVE cell groups migrate (open ar-

(dorsal) to the sulcus limitans (SL) while the basal plate and its related

row) to anterolateral areas of the tegmentum. Cell groups associated

GVE and GSE components are anterior (ventral) to the SL. In the adult

with the GSA functional component are displaced from their postero-

spinal cord, this general posterior/anterior relationship is maintained,

lateral position in the developing brainstem by the newly acquired cell

although the neural canal (as central canal) is reduced and/or absent.

groups having SSA components (as well as other structures). Conse-

Two major changes occur in the transition from spinal cord to brain-

quently, structures associated with the GSA component are located

stem in the adult. First, as the central canal of the cervical cord enlarges

(open arrow) in more anterolateral and lateral areas of the brainstem.

into the fourth ventricle and the cerebellum develops, the posterior

The approximate border between motor and sensory regions of the

portion of the neural tube is rotated laterally. Consequently, in the

brainstem is represented by an oblique line drawn through the brain-

adult, the sulcus limitans is present in the brainstem with motor com-

stem beginning at the SL. The medial (from midline) to lateral posi-

ponents (adult derivatives of the basal plate) medial to it, and sensory

tions of the various functional components, as shown on the far right

components (adult derivatives of the alar plate) are located laterally.

of this figure, are taken from their representative diagrams of brain-

Second, in the brainstem, special functional components (SVE to mus-

stem and cord and are directly translatable to Figure 7-2 (facing page).

cles of pharyngeal arch origin; SVA taste and olfaction; SSA vestibular,

The color-coding of the components on this figure correlate with that

auditory, and visual systems) are intermingled with the rostral contin-

in Figure 7-2 on the facing page.

uation of the general functional components as found in the spinal cord.

Abbreviations

GSA General somatic afferent

SSA Special somatic afferent

GSE General somatic efferent

SVA Special visceral afferent

GVA General visceral afferent

SVE Special visceral efferent

GVE General visceral efferent

SL Sulcus limitans

Cranial nerves

Components of Cranial and Spinal Nerves

175

E E

Midbrain

1. Oculomotor nuc. (GSE)

2. Edinger-Westphal nuc. (GVE)

3. Trochlear nuc. (GSE)

4. Mesencephalic nuc. & tr.

of V (GSA)

Pons

5. Abducens nuc. (GSE)

6. Sup. salivatory nuc. (GVE)

7. Motor trigeminal nuc. (SVE)

8. Motor facial nuc. (SVE)

9. Principle sensory nuc of V (GSA)

10. Spinal trigeminal nuc. (GSA)

(pars oralis)

Medulla oblongata

11. Hypoglossal nuc. (GSE)

12. Dorsal motor nuc. of vagus (GVE)

13. Inf. salivatory nuc. (GVE)

14. Nuc. ambiguus (SVE)

15. Solitary nuc. and tr.

15a: gustatory nuc. (SVA)

15b: cardiorespiratory nuc (GVA)

16. Vestibular nuclei (SSA)

S = Sup; L = Lat; M = Med; Sp. = Spinal

17. Cochlear nuc. (SSA)

18. Spinal trigeminal nuc. (GSA)

(pars interpolaris, pars caudalis)

Spinal cord

Cervical

cord

19. Medial motor cell column (GSE)

20. Accessory nuc. (GSE)

21. Lateral motor cell columns (GSE)

22. Intermediolateral cell column (GVE)

23. Visceral afferent receptive areas (GVA)

24. Substantia gelatinosa, nucleus proprious

and associated GSA receptive areas

Thoracic

25. Sacral parasympathetics (GVE)

cord

Lumbosacral

cord

Spinal nerves

7-2

The medial to lateral positions of brainstem cranial nerve

continuous cell groups) from one division of the brainstem to the

and spinal cord nuclei as shown here are the same as in Figure 7-1.

next or from brainstem to spinal cord. The nucleus ambiguus is a

This diagrammatic posterior (dorsal) view shows 1) the relative po-

column of cells composed of distinct cell clusters interspersed with

sitions and names of specific cell groups and their associated func-

more diffusely arranged cells, much like a string of beads. Nuclei as-

tional components, 2) the approximate location of particular nuclei

sociated with cranial nerves I (olfaction, SVA) and II (optic, SSA) are

in their specific division of brainstem and/or spinal cord, and 3) the

not shown. The color-coding used on this figure correlates with that

rostrocaudal continuity of cell columns (either as continuous or dis-

on Figure 7-1 (facing page).

176

Synopsis of Functional Components, Tracts, Pathways, and Systems

7-3

Orientation drawing for pathways. The trajectory of most

cospinal fibers are found in the internal capsule, crus cerebri, basilar

pathways illustrated in Chapter 7 appears on individualized versions of

pons, pyramid, and lateral corticospinal tract). Third, the location of ter-

this representation of the central nervous system (CNS). Although

minals containing specific neurotransmitters is indicated by the site(s) of

slight changes are made in each drawing, so as to more clearly diagram

termination of each tract (glutaminergic terminals of corticospinal fibers

a specific pathway, the basic configuration of the CNS is as represented

are located in the spinal cord gray matter). In addition, the action of most

here. This allows the user to move from pathway to pathway without

neuroactive substances is indicated as excitatory (

) or inhibitory (

being required to learn a different representation or drawing for each

This level of neurotransmitter information, as explained here for gluta-

pathway; also, laterality of the pathway, a feature essential to diagno-

minergic corticospinal fibers, is repeated for each pathway drawing.

sis (see introduction), is inherently evident in each illustration.

Clinical Correlations: The clinical correlations are designed to

The forebrain (telencephalon and diencephalon) is shown in the

give the user an overview of specific deficits (i.e., hemiplegia, athetosis)

coronal plane, and the midbrain, pons, medulla, and spinal cord are

seen in lesions of each pathway and to provide examples of some syn-

represented through their longitudinal axes. The internal capsule is

dromes or diseases (i.e., Brown-Sequard syndrome, Wilson disease) in

represented in the axial plane in an effort to show the rostrocaudal dis-

which these deficits are seen. Although purposefully brief, these cor-

tribution of fibers located therein.

relations highlight examples of deficits for each pathway and provide a

The reader should become familiar with the structures and regions

built-in mechanism for expanded study. For example, the words in

as shown here because their locations and relationships are easily trans-

italics in each correlation are clinical terms and phrases that are defined

ferable to subsequent illustrations. It may also be helpful to refer back

on the CD (from Stedman’s) included with this atlas or can be found

to this illustration when using subsequent sections of this chapter.

in standard medical dictionaries and clinical neuroscience textbooks.

Neurotransmitters: Three important facts are self-evident in the

Consulting these sources, especially the CD available in this atlas, will

descriptions of neurotransmitters that accompany each pathway draw-

significantly enhance understanding of the deficits seen in the neuro-

ing. These are illustrated by noting, as an example, that glutamate is

logically compromised patient. Expanded information, based on the

found in corticospinal fibers (see Figure 7-10). First, the location of neu-

deficits mentioned in this chapter, is integrated into some of the ques-

ronal cell bodies containing a specific transmitter is indicated (glutamate-

tions for chapter 7. Referring to such sources will allow the user to

containing cell bodies are found in cortical areas that project to the spinal

glean important clinical points that correlate with the pathway under

cord). Second, the trajectory of fibers containing a particular neurotrans-

consideration, and enlarge his or her knowledge and understanding by

mitter is obvious from the route taken by the tract (glutaminergic corti-

researching the italicized words and phrases.

Abbreviations

CE Cervical enlargement of spinal cord

IntCap,PL Internal capsule, posterior limb

Cer Cervical levels of spinal cord

LatSul Lateral sulcus (Sylvian sulcus)

CinSul Cingulate sulcus

LatVen Lateral ventricle

CaNu Caudate nucleus ( Put neostriatum)

LSE Lumbosacral enlargement of spinal cord

CM Centromedian (and intralaminar) nuclei

LumSac Lumbosacral level of spinal cord

CorCI Corpus callosum

L-VTh Lateral and ventral thalamic nuclei

Dien Diencephalon

excluding VPM and VPL

DMNu Dorsomedial nucleus of thalamus

Mes Mesencephalon

For Fornix

Met Metencephalon

GP Globus pallidus (paleostriatum)

Myelen Myelencephalon

GPl Globus pallidus, lateral segment

Put Putamen ( CaNu neostriatum)

GPm Globus pallidus, medial segment

SThNu Subthalamic nucleus

HyTh Hypothalamic area

Telen Telencephalon

IC Internal capsule

Thor Thoracic levels of spinal cord

IntCap,AL Internal capsule, anterior limb

VPL Ventral posterolateral nucleus of thalamus

IntCap,G Internal capsule, genu

VPM Ventral posteromedial nucleus of thalamus

178

Synopsis of Functional Components, Tracts, Pathways, and Systems

Posterior (Dorsal) Column-Medial Lemniscus System

7-4

The origin, course, and distribution of fibers composing the

used to describe deficits seen in lesions of the parietal cortex. Bilateral

posterior (dorsal) column (PC)-medial lemniscus (ML) system. This il-

damage (as in tabes dorsalis or subacute combined degeneration of the spinal

lustration shows the longitudinal extent, the positions in representa-

cord) produces bilateral losses. Although ataxia is the most common fea-

tive cross-sections of brainstem and spinal cord, and the somatotopy of

ture in patients with tabes dorsalis, they also have a loss of deep tendon

fibers in the PC and ML. The ML undergoes positional changes as it

reflexes, severe lancinating pain over the body below the head (more com-

courses from the myelencephalon (medulla) rostrally toward the mes-

mon in the lower extremity), and bladder dysfunction. The ataxia that

encephalic-diencephalic junction. In the medulla, ML and ALS fibers

may be seen in patients with posterior column lesions (sensory ataxia) is

are widely separated and receive different blood supplies, whereas in

due to a lack of proprioceptive input and position sense. These individ-

the midbrain, they are served by a common arterial source. As the ML

uals tend to forcibly place their feet to the floor in an attempt to stimu-

makes positional changes, the somatotopy therein follows accordingly.

late such sensory input. A patient with mild ataxia due to posterior col-

Fibers of the postsynaptic posterior column system (shown in green)

umn disease may compensate for the motor deficit by using visual cues.

are considered in detail in Figure 7-6 on page 182.

Patients with subacute combined degeneration (SCD) of the spinal cord

Neurotransmitters: Acetylcholine and the excitatory amino

first have signs and symptoms of posterior column involvement, fol-

acids glutamate and aspartate are associated with some of the large-

lowed later by signs of corticospinal tract damage (spastic weakness of legs,

diameter, heavily myelinated fibers of the posterior horn and posterior

increased deep tendon reflexes, Babinski sign).

columns.

Rostral to the sensory decussation, medial lemniscus lesions result

Clinical Correlations: Damage to posterior column fibers on one

in contralateral losses that include the entire body excluding the head.

side of the spinal cord (as in the Brown-Sequard syndrome) results in an ip-

Brainstem lesions involving medial lemniscus fibers usually include ad-

silateral loss of vibratory sensation, position sense, and discriminative

jacent structures, result in motor and additional sensory losses, and

touch (astereognosis, stereoagnosis) below the level of the lesion. The term

may reflect the distribution patterns of vessels (as in medial medullary or

stereoanesthesia is frequently used to specify a lesion of peripheral nerves

medial pontine syndromes). Large lesions in the forebrain may result in a

that results in an inability to perceive proprioceptive and tactile sensa-

complete contralateral loss of modalities carried in the posterior

tions. The term tactile agnosia is sometimes considered to be synony-

columns and anterolateral systems, or may produce pain (as in the thal-

mous with these preceding three terms. However, tactile agnosia is also

amic syndrome).

Abbreviations

ALS

Anterolateral system

NuGr Gracile nucleus

Basilar pons

PC Posterior column

Crus cerebri

PO Principal olivary nucleus

CTT

Central tegmental tract

PoCGy Postcentral gyrus

FCu

Cuneate fasciculus

PPGy Posterior paracentral gyrus

FGr

Gracile fasciculus

PRG Posterior (dorsal) root ganglia

IAF

Internal arcuate fibers

Py Pyramid

Internal capsule

RB Restiform body

Medial lemniscus

RNu Red nucleus

MLF

Medial longitudinal fasciculus

SN Substantia nigra

NuCu

Cuneate nucleus

VPL Ventral posterolateral nucleus of thalamus

Somatotopy of Body Areas

Fibers conveying input from upper extremity

S₅

Fibers from approximately the fifth sacral

Fibers conveying input from lower extremity

level

Fibers conveying input from neck

T₅

Fibers from approximately the fifth thoracic

Fibers conveying input from trunk

level

C₂

Fibers from approximately the second

cervical level

Review of Blood Supply to DC-ML System

STRUCTURES

ARTERIES

PC in Spinal Cord

penetrating branches of arterial vasocorona (see Figure 5-6)

ML in Medulla

anterior spinal (see Figure 5-14)

ML in Pons

overlap of paramedian and long circumferential branches of basilar

(see Figure 5-21)

ML in Midbrain

short circumferential branches of posterior cerebral and superior

cerebellar (see Figure 5-27)

VPL

thalamogeniculate branches of posterior cerebral (see Figure 5-38)

Posterior Limb of IC

lateral striate branches of middle cerebral (see Figure 5-38)

180

Synopsis of Functional Components, Tracts, Pathways, and Systems

Anterolateral System

7-5

The longitudinal extent and somatotopy of fibers composing the

fibers or projection neurons, conveying nociceptive (pain) informa-

anterolateral system (ALS). The ALS is a composite bundle containing

tion.

ascending fibers that terminate in the reticular formation (spinoreticu-

Clinical Correlations: Spinal lesions involving the anterolateral

lar fibers), the mesencephalon (spinotectal fibers to deep layers of the

system (as in the Brown-Sequard syndrome) result in a loss of pain and

superior colliculus, spinoperiaqueductal fibers to the periaqueductal

temperature sensations on the contralateral side of the body beginning

grey), the hypothalamus (spinohypothalamic fibers), and the sensory re-

one to two levels caudal to the lesion. Syringomyelia produces bilateral

lay nuclei of the dorsal thalamus (spinothalamic fibers). Other fibers in

sensory losses restricted to adjacent dermatomes because of damage to

the ALS include spinoolivary projections to the accessory olivary nuclei.

the anterior (ventral) white commissure. Vascular lesions in the spinal

Spinothalamic fibers terminate primarily in the VPL and reticulothala-

cord (such as acute central cervical cord syndrome) may result in a bilateral

mic fibers terminate in some intralaminar nuclei, and in medial areas of

and splotchy loss of pain and thermal sense below the lesion because

the posterior thalamic complex.

the ALS has a dual vascular supply.

Fibers from the PAG and nucleus raphe dorsalis enter the nucleus

Vascular lesions in the lateral medulla (posterior inferior cerebellar artery

raphe magnus and adjacent reticular area. These latter sites, in turn,

syndrome) or lateral pons (anterior inferior cerebellar artery occlusion)

project to laminae I, II, and V of the spinal cord via raphespinal and

result in a loss of pain and thermal sensations over the entire contralat-

reticulospinal fibers that participate in the modulation of pain trans-

eral side of the body (ALS) as well as on the ipsilateral face (spinal

mission in the spinal cord.

trigeminal tract and nucleus), coupled with other motor and/or sensory

Neurotransmitters: Glutamate

(

), calcitonin gene-related

deficits based on damage to structures these vessels serve. Note that the

peptide, and substance P(

)-containing posterior (dorsal) root gan-

ALS and PC-ML systems are separated in the medulla (in different vas-

glion cells project into laminae I, II (heavy), V (moderate), and III, IV

cular territories) but are adjacent to each other in the midbrain (basi-

(sparse). Some spinoreticular and spinothalamic fibers contain

cally in the same vascular territory). Consequently, medullary lesions

enkephalin (

), somatostatin (

), and cholecystokinin (

). In addi-

will not result in deficits related to both pathways, while a lesion in the

tion to enkephalin and somatostatin, some spinomesencephalic fibers

midbrain may result in a contralateral loss of pain, thermal, vibratory,

contain vasoactive intestinal polypeptide (

). Neurons in the PAG and

and discriminative touch sensations on the body, excluding the head.

nucleus raphe dorsalis containing serotonin and neurotensin project

Profound loss of posterior column and anterolateral system modali-

into the nuclei raphe magnus and adjacent reticular formation. Cells in

ties, or intractable pain and/or paresthesias (as in the thalamic syndrome),

these latter centers that contain serotonin and enkephalin send

may result from vascular lesions in the posterolateral thalamus. So-

processes to spinal cord laminae I, II, and V. Serotonergic raphespinal

called thalamic pain may also be experienced by patients who have

or enkephalinergic reticulospinal fibers may inhibit primary sensory

brainstem lesions.

Abbreviations

Input from upper extremity regions

PRG Posterior (dorsal) root ganglion

ALS

Anterolateral system

Py Pyramid

AWCom

Anterior (ventral) white commissure

RaSp Raphespinal fibers

Crus cerebri

RB Restiform body

Internal capsule

RetF Reticular formation (of midbrain)

Input from lower extremity regions

RetTh Reticulothalamic fibers

MCP

Middle cerebellar peduncle

RNu Red nucleus

Medial lemniscus

S Input from sacral regions

MLF

Medial longitudinal fasciculus

SC Superior colliculus

Nuclei

SpRet Spinoreticular fibers

NuDark

Nucleus of Darkschewitsch

SpTec Spinotectal fibers

NuRa,d

Nucleus raphe, dorsalis

SpTh Spinothalamic fibers

NuRa,m

Nucleus raphe, magnus

T Input from thoracic regions

PAG

Periaqueductal gray

VPL Ventral posterolateral nucleus of thalamus

PoCGy

Postcentral gyrus

I-VIII Laminae I-VIII of Rexed

PPGy

Posterior paracentral gyrus

Review of Blood Supply to ALS

STRUCTURES

ARTERIES

ALS in Spinal Cord penetrating branches of arterial vasocorona and branches of central

(see Figures 5-6 and 5-14)

ALS in Medulla

caudal third, vertebral; rostral two-thirds, posterior inferior cerebellar

(see Figure 5-14)

ALS in Pons

long circumferential branches of basilar (see Figure 5-21)

ALS in Midbrain

short circumferential branches of posterior cerebral, superior

cerebellar (see Figure 5-27)

VPL

thalamogeniculate branches of posterior cerebral (see Figure 5-38)

Posterior Limb of IC

lateral striate branches of middle cerebral (see Figure 5-38)

182

Synopsis of Functional Components, Tracts, Pathways, and Systems

Postsynaptic-Posterior (Dorsal) Column System and the

Spinocervicothalamic Pathway

7-6

The origin, course, and distribution of fibers composing the

cal nucleus and the dorsal column nuclei, glutamate (and substance P)

postsynaptic-posterior column system (upper) and the spinocervi-

may also be present in some postsynaptic dorsal column fibers.

cothalamic pathway (lower). Postsynaptic-posterior column fibers

Clinical Correlations: The postsynaptic-posterior column and

originate primarily from cells in lamina IV (some cells in laminae III and

spinocervicothalamic pathways are not known to be major circuits in

V-II also contribute), ascend in the ipsilateral dorsal fasciculi, and end

the human nervous system. However, the occurrence of these fibers

in their respective nuclei in the caudal medulla. Moderate-to-sparse

may explain a well known clinical observation. Patients that have re-

collaterals project to a few other medullary targets.

ceived an anterolateral cordotomy (this lesion is placed just ventral to the

Fibers of the spinocervical part of the spinocervicothalamic pathway

denticulate ligament) for intractable pain may experience complete or

also originate from cells in lamina IV (less so from III and V). The axons

partial relief, or there may be a recurrence of pain perception within

of these cells ascend in the posterior part of the lateral funiculus (this is

days or weeks. Although the cordotomy transects fibers of the antero-

sometimes called the dorsolateral funiculus) and end in a topographic

lateral system (the main pain pathway), this lesion spares the posterior

fashion in the lateral cervical nucleus: lumbosacral projections termi-

horn, posterior columns, and spinocervical fibers. Consequently, the

nate posterolaterally and cervical projections anteromedially. Cells of

recurrence of pain perception (or even the partial relief of pain) in

the posterior column nuclei and the lateral cervical nucleus convey in-

these patients may be explained by these postsynaptic-dorsal column

formation to the contralateral thalamus via the medial lemniscus.

and spinocervicothalamic projections. Through these connections,

Neurotransmitters: Glutamate (

) and possibly substance P

some nociceptive (pain) information may be transmitted to the ventral

(

) are present in some spinocervical projections. Because some cells

posterolateral nucleus and on to the sensory cortex, via circuits that by-

in laminae III-V have axons that collateralize to both the lateral cervi-

pass the anterolateral system and are spared in a cordotomy.

Abbreviations

ALS Anterolateral system

AWCom Anterior (ventral) white commissure

FCu Cuneate fasciculus

FGr Gracile fasciculus

IAF Internal arcuate fibers

LCerNu Lateral cervical nucleus

ML Medial lemniscus

NuCu Cuneate nucleus

NuGr Gracile nucleus

PRG Posterior (dorsal) root ganglion

Review of Blood Supply to Dorsal Horn, FGr, FCu, LCerNu

STRUCTURES

ARTERIES

FGr, FCu in Spinal Cord penetrating branches of arterial vasocorona and some branches

from central (sulcal) (see Figure 5-6)

LCerNu

penetrating branches of arterial vasocorona and branches from

central (see Figure 5-6)

NuGr NuCu

posterior spinal (see Figure 5-14)

184

Synopsis of Functional Components, Tracts, Pathways, and Systems

Trigeminal Pathways

7-7

The distribution of general sensory (GSA) information origi-

tile sensation from the ipsilateral face, oral cavity, and teeth; 2) ipsilat-

nating on cranial nerves V (trigeminal), VII (facial), IX (glossopharyn-

eral paralysis of masticatory muscles; and 3) ipsilateral loss of the

geal), and X (vagus). Some of these primary sensory fibers end in the

corneal reflex. Damage to peripheral portions of the trigeminal nerve

chief sensory nucleus, but most form the spinal trigeminal tract and

may be traumatic (skull fracture, especially of supraorbital and infraor-

end in the spinal trigeminal nucleus.

bital branch), inflammatory (as in herpes zoster), or result from tumor

Neurons in the spinal trigeminal nucleus and in ventral parts of the

growth. The deficit would reflect the peripheral portion of the trigem-

chief sensory nucleus give rise to crossed anterior (ventral) trigeminothal-

inal nerve damaged.

amic fibers. Collaterals of these ascending fibers influence the hy-

Trigeminal neuralgia (tic douloureux) is a severe burning pain restricted

poglossal, facial (corneal reflex, supraorbital, or trigeminofacial reflex), and

to the peripheral distribution of the trigeminal nerve, usually its V₂

trigeminal motor nuclei; mesencephalic collaterals are involved in the

(maxillary) division. This pain may be initiated by any contact to areas

jaw reflex, also called the jaw-jerk reflex. Collaterals also enter the dorsal

of the face such as the corner of the mouth, nose, lips, or cheek (e.g.,

motor vagal nucleus (vomiting reflex), the superior salivatory nucleus

shaving, putting make-up on, chewing, or even smiling). The attacks

(tearing/lacrimal reflex), and the nucleus ambiguus and adjacent reticular

frequently occur without warning, may happen only a few times a

formation (sneezing reflex). Uncrossed posterior (dorsal) trigeminothal-

month to many times in a single day, and are usually seen in patients

amic fibers arise from posterior regions of the chief sensory nucleus.

40 years of age or older. One probable cause of trigeminal neuralgia is

Neurotransmitters: Substance P (

)-containing and cholecys-

compression of the trigeminal root by aberrant vessels, most com-

tokinin (

)-containing trigeminal ganglion cells project to the spinal

monly a loop of the superior cerebellar artery (see page 41). Other

trigeminal nucleus, especially its caudal part (pars caudalis). Glutamate

causes may include tumor, multiple sclerosis, and ephaptic transmission

(

) is found in many trigeminothalamic fibers arising from the chief sen-

(ephapse) in the trigeminal ganglion. This is the most common type of

sory nucleus and the pars interpolaris of the spinal nucleus. It is present

neuralgia.

in fewer trigeminothalamic fibers from the pars caudalis and in almost

In the medulla, fibers of the spinal trigeminal tract and ALS are

none from the pars oralis. The locus ceruleus (noradrenergic fibers) and

served by the posterior inferior cerebellar artery (PICA). Conse-

the raphe nuclei (serotonergic fibers) also project to the spinal nucleus.

quently, an alternating hemianesthesia is one characteristic feature of the

Enkephalin (

)-containing cells are present in caudal regions of the

PICA syndrome. This is a loss of pain and thermal sensations on one side

spinal nucleus, and enkephalinergic fibers are found in the nucleus am-

of the body and the opposite side of the face. Pontine gliomas may pro-

biguus and in the hypoglossal, facial, and trigeminal motor nuclei.

duce a paralysis of masticatory muscles (motor trigeminal damage) and

Clinical Correlations: Lesions of the trigeminal ganglion or nerve

some loss of tactile input (chief sensory nucleus damage), as well as

proximal to the ganglion result in 1) a loss of pain, temperature, and tac-

other deficits based on what adjacent structures may be involved.

Abbreviations

ALS

Anterolateral system

MesNu Mesencephalic nucleus

VPM Ventral posteromedial nucleus

Crus cerebri

ML Medial lemniscus

of thalamus

CSNu

Chief (principal) sensory

OpthV Ophthalmic division of

VTTr Ventral trigeminothalamic

nucleus

trigeminal nerve

tract

DTTr

Dorsal trigeminothalamic tract

RB Restiform body

FacNu

Facial nucleus

RetF Reticular formation

Ganglia

GSA

General somatic afferent

RNu Red nucleus

Trigeminal ganglion

HyNu

Hypoglossal nucleus

SpTNu Spinal trigeminal nucleus

Geniculate ganglion

Internal capsule

SpTTr Spinal trigeminal tract

Superior of glossopharyngeal

ManV

Mandibular division of

TriMoNu Trigeminal motor nucleus

Superior of vagus

trigeminal nerve

TMJ Temporomandibular joint

MaxV

Maxillary division of trigeminal

VPL Ventral posterolateral nucleus

nerve

of thalamus

Review of Blood Supply to SpTT, SpTNu,

and Trigeminothalamic Tracts

STRUCTURES

ARTERIES

SpTTr and SpTNu

caudal third, vertebral; rostral two-thirds, posterior

in Medulla

inferior cerebellar (see Figure 5-14)

SpTTr and SpTNu in Pons long circumferential branches of basilar (see Figure 5-21)

Trigeminothalamic Fibers

short circumferential branches of posterior cerebral and

in Midbrain

superior cerebellar (see Figure 5-27)

VPM

thalamogeniculate branches of posterior cerebral

(see Figure 5-38)

Posterior Limb of IC

lateral striate branches of middle cerebral (see Figure 5-38)

186

Synopsis of Functional Components, Tracts, Pathways, and Systems

Solitary Pathways

7-8

Visceral afferent input (SVA-taste; GVA general visceral sen-

adjacent dorsal motor vagal nucleus. Cholecystokinin (

), somato-

sation) on cranial nerves VII (facial), IX (glossopharyngeal), and X (va-

statin (

), and enkephalin (

) are present in solitary neurons, in cells

gus) enters the solitary nuclei via the solitary tract. What we com-

of the parabrachial nuclei, and in some thalamic neurons that project

monly call the solitary “nucleus” is actually a series of small nuclei that

to taste, and other visceral areas, of the cortex.

collectively form this rostrocaudal-oriented cell column.

Clinical Correlations: Lesions of the geniculate ganglion, or fa-

Solitary cells project to the salivatory, hypoglossal, and dorsal mo-

cial nerve proximal to the ganglion, result in 1) ipsilateral loss of taste

tor vagal nuclei and the nucleus ambiguus. Solitary projections to the

(ageusia) from the anterior two-thirds of the tongue and 2) an ipsilateral

nucleus ambiguus are largely bilateral and are the intermediate neurons

facial (Bell) palsy. Although a glossopharyngeal nerve lesion will result in

in the pathway for the gag reflex. The afferent limb of the gag-reflex is

ageusia from the posterior third of the tongue on the ipsilateral side, this

carried on the glossopharyngeal nerve, and the efferent limb originates

loss is difficult to test. On the other hand, glossopharyngeal neuralgia is an

from the nucleus ambiguus. In this respect, the efferent limb travels on

idiopathic pain localized to the peripheral sensory branches of the IXth

both the glossopharyngeal and vagus nerves. Although not routinely

nerve in the posterior pharynx, posterior tongue, and tonsillar area. Al-

tested, the gag-reflex should be evaluated in patients with dysarthria, dys-

though comparatively rare, glossopharyngeal neuralgia may be aggra-

phagia, or hoarnessness. Solitariospinal fibers are bilateral with a con-

vated by talking or even swallowing. Occlusion of the posterior inferior

tralateral preponderance and project to the phrenic nucleus, the inter-

cerebellar artery (as in the posterior inferior cerebellar artery or lateral

mediolateral cell column, and the ventral horn. The VPM is the

medullary syndrome), in addition to producing an alternate hemianesthesia,

thalamic center through which visceral afferent information is relayed

will also result in ageusia from the ipsilateral side of the tongue because

onto the cerebral cortex.

the posterior inferior cerebellar artery serves the solitary tract and nu-

Neurotransmitters: Substance P (

)-containing and cholecys-

clei in the medulla.

tokinin (

)-containing cells in the geniculate ganglion (facial nerve)

Interestingly, lesions of the olfactory nerves or tract (anosmia, loss

and in the inferior ganglia of the glossopharyngeal and vagus nerves

of olfactory sensation; dysosmia, distorted olfactory sense) may affect

project to the solitary nucleus. Enkephalin (

), neurotensin, and

how the patient perceives taste. Witness the fact that the nasal conges-

GABA (

) are present in some solitary neurons that project into the tion accompanying a severe cold will markedly affect the sense of taste.

Abbreviations

AmyNu Amygdaloid nucleus (complex)

SalNu Salivatory nuclei

CardResp Cardiorespiratory portion (caudal) of

SolTr & Nu Solitary tract and nuclei

solitary nucleus

SVA Special visceral afferent

GustNu Gustatory nucleus (rostral portion of

Tr Tract

solitary nucleus)

VA Visceral afferent

GVA General visceral afferent

VPM Ventral posteromedial nucleus of

HyNu Hypoglossal nucleus

thalamus

HyTh Hypothalamus

Inf VNu Inferior (or spinal) vestibular nucleus

Number Key

MVNu Medial vestibular nucleus

Geniculate ganglion of facial

NuAm Nucleus ambiguus

Inferior ganglion of glossopharyngeal

PBNu Parabrachial nuclei

Inferior ganglion of vagus

RB Restiform body

Dorsal motor vagal nucleus

Review of Blood Supply to SolNu and SolTr

STRUCTURES

ARTERIES

SolNu and Tr in

caudal medulla, anterior spinal; rostral medulla, posterior inferior

inferior cerebellar

cerebellar (See Figure 5-14)

Ascending Fibers

long circumferential branches of basilar and branches of superior

in Pons

cerebellar (see Figure 5-21)

VPM

thalamogeniculate branches of posterior cerebral (see Figure 5-38)

Posterior Limb of IC

lateral striate branches of middle cerebral (see Figure 5-38)

190

Synopsis of Functional Components, Tracts, Pathways, and Systems

Corticospinal Tracts

7-10

The longitudinal extent of corticospinal fibers and their posi-

is a hallmark of this disease. Ocular muscles are usually affected first

tion and somatotopy at representative levels within the neuraxis. The

(diplopia, ptosis), and in approximately 50% of patients, facial and

somatotopy of corticospinal fibers in the basilar pons is less obvious than

oropharyngeal muscles are commonly affected ( facial weakness, dys-

in the internal capsule, crus cerebri, pyramid, or spinal cord. In the de-

phagia, dysarthria). Weakness may also be seen in limb muscles but al-

cussation of the pyramids, fibers originating from upper extremity ar-

most always in combination with facial/oral weaknesses.

eas of the cerebral cortex cross rostral to those that arise from lower ex-

Injury to corticospinal fibers on one side of the cervical spinal cord

tremity areas. In addition to fibers arising from the somatomotor area

(as in the Brown-Sequard syndrome) results in weakness (hemiparesis) or

of the cerebral cortex (area 4), a significant contingent also originate

paralysis (hemiplegia) of the ipsilateral upper and lower extremities. In

from the postcentral gyrus (areas 3, 1, 2); the former terminate pri-

addition, and with time, these patients may exhibit features of an upper

marily in laminae VI-IX, while the latter end mainly in laminae IV and

motor neuron lesion (hyperreflexia, spasticity, loss of superficial abdominal

V. Prefrontal regions, especially area 6, and parietal areas 5 and 7 also

reflexes, and the Babinski sign). Bilateral cervical spinal cord damage

contribute to the corticospinal tract.

above C4-C5 may result in paralysis of all four extremities (quadriple-

Neurotransmitters: Acetylcholine, gamma-aminobutyric acid

gia). Unilateral spinal cord lesions in thoracic levels may result in paral-

(

), and substance P (

, plus other peptides) are found in small cor-

ysis of the ipsilateral lower extremity (monoplegia). If the thoracic spinal

tical neurons presumed to function as local circuit cells or in cortico-

cord damage is bilateral both lower extremities may be paralyzed ( para-

cortical connections. Glutamate (

) is present in cortical efferent

plegia). Small lesions within the decussation of the pyramids may result

fibers that project to the spinal cord. Glutaminergic corticospinal fibers

in a bilateral paresis of the upper extremities (lesion in rostral portions)

and terminals are found in all spinal levels but are especially concen-

or a bilateral paresis of the lower extremities (lesion in caudal portions)

trated in cervical and lumbosacral enlargements. This correlates with

based on the crossing patterns of fibers within the decussation.

the fact that approximately 55% of all corticospinal fibers terminate in

Rostral to the pyramidal decussation, vascular lesions in the medulla

cervical levels of the spinal cord, approximately 20% in thoracic lev-

(the medial medullary syndrome), pons (the Millard-Gubler or Foville syn-

els, and approximately 25% in lumbosacral levels. Some corticospinal

dromes), or midbrain

(the Weber syndrome) all produce alternating

fibers may branch and terminate at multiple spinal levels. Lower mo-

(crossed) hemiplegias. These present as a contralateral hemiplegia of the

tor neurons are influenced by corticospinal fibers either directly or in-

upper and lower extremities, coupled with an ipsilateral paralysis of

directly via interneurons. Acetylcholine and calcitonin gene-related

the tongue (medulla), facial muscles or lateral rectus muscle (pons),

peptides are present in these large motor cells and in their endings in

and most eye movements (midbrain). Sensory deficits are frequently

skeletal muscle.

seen as part of these syndromes. Lesions in the internal capsule (lacu-

Clinical Correlations: Myasthenia gravis, a disease characterized

nar strokes) produce contralateral hemiparesis sometimes coupled with

by moderate to profound weakness of skeletal muscles, is caused by

various cranial nerve signs due to corticonuclear (corticobulbar) fiber

circulating antibodies that react with postsynaptic nicotinic acetyl-

involvement. Bilateral weakness, indicative of corticospinal involve-

choline receptors. Progressive muscle fatigability throughout the day

ment, is also present in amyotrophic lateral sclerosis.

Abbreviations

ACSp Anterior corticospinal tract

LCSp Lateral corticospinal tract

Somatotopy of CSp Fibers

ALS Anterolateral system

ML Medial lemniscus

A Position of fibers coursing to

APGy Anterior paracentral gyrus

MLF Medial longitudinal fasciculus

upper extremity regions of

BP Basilar pons

PO Principal olivary nucleus

spinal cord

CC Crus cerebri

PrCGy Precentral gyrus

L Position of fibers coursing to

CNu Corticonuclear (corticobulbar)

Py Pyramid

lower extremity regions of

fibers

RB Restiform body

spinal cord

CSp Corticospinal fibers

RNu Red nucleus

T Position of fibers coursing to

IC Internal capsule

SN Substantia nigra

thoracic regions of spinal cord

Review of Blood Supply to Corticospinal Fibers

STRUCTURES

ARTERIES

Posterior Limb of IC

lateral striate branches of middle cerebral (see

Figure 5-38)

Crus Cerebri in

paramedian and short circumferential

Midbrain

branches of basilar and posterior

communicating (see Figure 5-27)

CSp in BP

paramedian branches of basilar (see Figure 5-21)

Py in Medulla

anterior spinal (see Figure 5-14)

LCSp in Spinal Cord

penetrating branches of arterial vasocorona (leg

fibers), branches of central artery (arm fibers)

(See Figure 5-6)

192

Synopsis of Functional Components, Tracts, Pathways, and Systems

Corticonuclear (Corticobulbar) Fibers

7-11

The origin, course, and distribution of corticonuclear (corti-

may produce a transient gaze palsy in which the eyes deviate toward the

cobulbar) fibers to brainstem motor nuclei. These fibers influence—ei-

lesioned side and away from the side of the hemiplegia. In addition to

ther directly or through neurons in the immediately adjacent reticular

a contralateral hemiplegia, common cranial nerve findings in capsular le-

formation—the motor nuclei of oculomotor, trochlear, trigeminal, ab-

sions may include 1) deviation of the tongue toward the side of the

ducens, facial, glossopharyngeal and vagus (both via nucleus ambiguus),

weakness and away from the side of the lesion when protruded and 2)

spinal accessory, and hypoglossal nerves.

paralysis of facial muscles on the contralateral lower half of the face

Corticonuclear (corticobulbar) fibers arise in the frontal eye fields (ar-

(central facial palsy). This reflects the fact that corticonuclear (cortico-

eas 6 and 8 in caudal portions of the middle frontal gyrus), the precen-

bulbar) fibers to genioglossus motor neurons and to facial motor neu-

tral gyrus (somatomotor cortex, area 4), and some originate from the

rons serving the lower face are primarily crossed. Interruption of cor-

postcentral gyrus (areas 3,1, 2). Fibers from area 4 occupy the genu of

ticonuclear fibers to the nucleus ambiguus may result in weakness of

the internal capsule, but those from the frontal eye fields (areas 8,6) may

palatal muscles contralateral to the lesion; the uvula will deviate to-

traverse caudal portions of the anterior limb, and some (from areas

wards the ipsilateral (lesioned) side on attempted phonation. In addi-

3,1,2), may occupy the most rostral portions of the posterior limb.

tion, a lesion involving corticonuclear fibers to the accessory nucleus

Fibers that arise in areas 8 and 6 terminate in the rostral interstitial nucleus

may result in drooping of the ipsilateral shoulder (or an inability to el-

of the medial longitudinal fasciculus (vertical gaze center) and in the parame-

evate the shoulder against resistance) due to trapezius weakness, and

dian pontine reticular formation (horizontal gaze center); these areas, in turn,

difficulty in turning the head (against resistance) to the contralateral

project respectively to the IIIrd and IVth, and to the VIth nuclei. Fibers

side due to weakness of the sternocleidomastoid muscle. In contrast to

from area 4 terminate in, or adjacent to, cranial nerve motor nuclei ex-

the alternating hemiplegia seen in some brainstem lesions, hemisphere

cluding those of III, IV, and VI.

lesions result in spinal and cranial nerve deficits that are generally, but

Although not illustrated here, the superior colliculus receives cor-

not exclusively, contralateral to the cerebral injury.

tical input from area 8 and from the parietal eye field (area 7) and also

Brainstem lesions, especially in the midbrain or pons, may result in

projects to the riMLF and PPRF. In addition, it is important to note

the following: 1) vertical gaze palsies (midbrain), 2) the Parinaud syn-

that descending cortical fibers (many arising in areas 3, 1, 2) project to

drome—paralysis of upward gaze (tumors in area of pineal), 3) internu-

sensory relay nuclei of some cranial nerves and to other sensory relay

clear ophthalmoplegia (lesion in MLF between motor nuclei of III and

nuclei in the brainstem, such as those of the posterior column system.

VI), 4) horizontal gaze palsies (lesion in PPRF), or 5) the one-and-a-half

Neurotransmitters: Glutamate (

) is found in many corticofu-

syndrome. In the latter case, the lesion is adjacent to the midline and in-

gal axons that directly innervate cranial nerve motor nuclei and in

volves the abducens nucleus and adjacent PPRF, internuclear fibers

those fibers that terminate near (indirect), but not in, the various mo-

from the ipsilateral abducens that are crossing to enter the contralat-

tor nuclei.

eral MLF, and internuclear fibers from the contralateral abducens nu-

Clinical Correlations: Lesions involving the motor cortex (as in

cleus that cross to enter the MLF on the ipsilateral (lesioned) side. The

cerebral artery occlusion) or the internal capsule (as in lacunar strokes

result is a loss of ipsilateral abduction (lateral rectus) and adduction

or occlusion of lenticulostriate branches of M₁) give rise to a con-

(medial rectus, the “one”) and a contralateral loss of adduction (medial

tralateral hemiplegia of the arm and leg (corticospinal fiber involve-

rectus, the “half ”); the only remaining horizontal movement is con-

ment) coupled with certain cranial nerve signs. Strictly cortical lesions

tralateral abduction via the intact abducens motor neurons.

Abbreviations

AbdNu Abducens nucleus

OcNu Oculomotor nucleus

AccNu Accessory nucleus (spinal accessory nu.)

PPRF Paramedian pontine reticular formation

FacNu Facial nucleus

riMLF Rostral interstitial nucleus of the medial

HyNu Hypoglossal nucleus

longitudinal fasciculus

IC Internal capsule

TriMoNu Trigeminal motor nucleus

NuAm Nucleus ambiguus

TroNu Trochlear nucleus

Review of Blood Supply to Cranial Nerve Motor Nuclei

STRUCTURES

ARTERIES

OcNu and EWNu

paramedian branches of basilar bifurcation and medial branches

of posterior cerebral and posterior communicating (see Figure

5-27)

TriMoNu

long circumferential branches of basilar (see Figure 5-21)

AbdNu and FacNu

long circumferential branches of basilar (see Figure 5-21)

NuAm

posterior inferior cerebellar (see Figure 5-14)

HyNu

anterior spinal (see Figure 5-14)

194

Synopsis of Functional Components, Tracts, Pathways, and Systems

Tectospinal and Reticulospinal Tracts

7-12

The origin, course, position in representative cross-sections

ing system that modulates pain transmission at the spinal level. Many

of brainstem and spinal cord, and the general distribution of tectospinal

reticulospinal fibers influence the activity of lower motor neurons.

and reticulospinal tracts. Tectospinal fibers originate from deeper lay-

Clinical Correlations: Isolated lesions of only tectospinal and

ers of the superior colliculus, cross in the posterior (dorsal) tegmental

reticulospinal fibers are essentially never seen. Tectospinal fibers pro-

decussation, and distribute to cervical cord levels. Several regions of

ject to upper cervical levels where they influence reflex movement of

cerebral cortex (e.g., frontal, parietal, temporal) project to the tec-

the head and neck. Such movements may be diminished or slowed in

tum, but the most highly organized corticotectal projections arise from

patients with damage to these fibers. Pontoreticulospinal (medial retic-

the visual cortex. Pontoreticulospinal fibers (medial reticulospinal)

ulospinal) fibers are excitatory to extensor motor neurons and to neu-

tend to be uncrossed, while those from the medulla (bulboreticu-

rons innervating axial musculature; some of these fibers may also in-

lospinal or lateral reticulospinal) are bilateral but with a pronounced

hibit flexor motor neurons. In contrast, some bulboreticulospinal

ipsilateral preponderance. Corticoreticular fibers are bilateral with a

(lateral reticulospinal) fibers are primarily inhibitory to extensor mo-

slight contralateral preponderance and originate from several cortical

tor neurons and to neurons innervating muscles of the neck and back;

areas.

these fibers may also excite flexor motor neurons via interneurons.

Neurotransmitters: Corticotectal projections, especially those

Reticulospinal (and vestibulospinal) fibers contribute to the spasticity

from the visual cortex, utilize glutamate (

). This substance is also

that develops in patients having lesions of corticospinal fibers. These

present in most corticoreticular fibers. Some neurons of the giganto-

reticulospinal and vestibulospinal fibers (see Figure 7-13 on page 196)

cellular reticular nucleus that send their axons to the spinal cord, as

also contribute to the tonic extension of the arms and legs seen in de-

reticulospinal projections, contain enkephalin (

) and substance P

cerebrate rigidity when spinal motor neurons are released from de-

(

). Enkephalinergic reticulospinal fibers may be part of the descend- scending cortical control.

Abbreviations

ALS Anterolateral system

PO Principal olivary nucleus

ATegDec Anterior tegmental decussation

PTegDec Posterior tegmental decussation

(rubrospinal fibers)

(tectospinal fibers)

BP Basilar pons

Py Pyramid

CC Crus cerebri

RB Restiform body

CRet Corticoreticular fibers

RetNu Reticular nuclei

CTec Corticotectal fibers

RetSp Reticulospinal tract(s)

GigRetNu Gigantocellular reticular nucleus

RNu Red nucleus

LCSp Lateral corticospinal tract

RuSp Rubrospinal tract

ML Medial lemniscus

SC Superior colliculus

MLF Medial longitudinal fasciculus

SN Substantia nigra

MVNu Medial vestibular nucleus

SpVNu Spinal (or inferior) vestibular nucleus

OcNu Oculomotor nucleus

TecSp Tectospinal tract

Review of Blood Supply to SC, Reticular Formation of Pons

and Medulla, and TecSp and RetSp Tracts in Cord

STRUCTURES

ARTERIES

long circumferential branches (quadrigeminal branch) of posterior

cerebral plus some from superior cerebellar and posterior

choroidal (see Figure 5-27)

Pontine Reticular

long circumferential branches of basilar plus branches of superior

Formation

cerebellar in rostral pons (see Figure 5-21)

Medullary Recticular

branches of vertebral plus paramedian branches of basilar at

Formation

medulla-pons junction (see Figure 5-14)

TecSp and RetSp

branches of central artery (TecSp and Medullary RetSp); Tracts

penetrating branches of arterial vasocorona (Pontine RetSp) (see

Figures 5-14 and 5-6)

196

Synopsis of Functional Components, Tracts, Pathways, and Systems

Rubrospinal and Vestibulospinal Tracts

7-13

The origin, course, and position in representative cross-sec-

Clinical Correlations: Isolated injury to rubrospinal and vestibu-

tions of brainstem and spinal cord, and the general distribution of

lospinal fibers is really not seen in humans. Deficits in fine distal limb

rubrospinal and vestibulospinal tracts. Rubrospinal fibers cross in the an-

movements seen in monkeys following experimental rubrospinal le-

terior (ventral) tegmental decussation and distribute to all spinal levels

sions may be present in humans. However, these deficits are over-

although projections to cervical levels clearly predominate. Cells in dor-

shadowed by the hemiplegia associated with injury to the adjacent cor-

somedial regions of the red nucleus receive input from upper extremity

ticospinal fibers. The contralateral tremor seen in patients with the

areas of the motor cortex and project to cervical cord, but those in ven-

Claude syndrome (a lesion of the medial midbrain) is partially related to

trolateral areas of the nucleus receive some fibers from lower extremity

damage to the red nucleus as well as to the adjacent cerebellothalamic

areas of the motor cortex and may project in sparse numbers to lum-

fibers. These patients may also have a paucity of most eye movement

bosacral levels. The red nucleus also projects, via the central tegmental

on the ipsilateral side and a dilated pupil (mydriasis) due to concurrent

tract, to the ipsilateral inferior olivary complex (rubroolivary fibers).

damage to exiting rootlets of the oculomotor nerve.

Medial and lateral vestibular nuclei give rise to the medial and lateral

Medial vestibulospinal fibers primarily inhibit motor neurons inner-

vestibulospinal tracts, respectively. The former tract is primarily ipsi-

vating extensors and neurons serving muscles of the back and neck. Lat-

lateral, projects to upper spinal levels, and is considered a component

eral vestibulospinal fibers may inhibit some flexor motor neurons, but

of the medial longitudinal fasciculus in the spinal cord. The latter tract

they mainly facilitate spinal reflexes via their excitatory influence on spinal

is ipsilateral and somatotopically organized; fibers to lumbosacral levels

motor neurons innervating extensors. Vestibulospinal and reticulospinal

originate from dorsal and caudal regions of the lateral nucleus, while

(see Figure 7-12 on page 194) fibers contribute to the spasticity seen in pa-

those to cervical levels arise from its rostral and more ventral areas.

tients with damage to corticospinal fibers or to the tonic extension of the

Neurotransmitters: Glutamate (

) is present in corticorubral

extremities in patients with decerebrate rigidity. In the case of decerebrate

fibers. Some lateral vestibulospinal fibers contain aspartate

(

rigidity, the descending influences on spinal flexor motor neurons (corti-

whereas glycine (

) is present in a portion of the medial vestibu-

cospinal, rubrospinal) is removed; the descending brainstem influence on

lospinal projection. There are numerous gamma-aminobutyric acid

spinal extensor motor neurons predominates; this is augmented by exci-

(

)-containing fibers in the vestibular complex; these represent the

tatory spinoreticular input (via ALS) to some of the centers giving rise to

endings of cerebellar corticovestibular fibers.

reticulospinal fibers (see also Figure 7-12 on page 194).

Abbreviations

ATegDec Anterior tegmental decussation

MVessp Medial vestibulospinal tract

(rubrospinal fibers)

MVNu Medial vestibular nucleus

CC Crus cerebri

OcNu Oculomotor nucleus

CorRu Corticorubral fibers

PTegDec Posterior tegmental decussation (tectospinal

FacNu Facial nucleus

fibers)

InfVNu Inferior (or spinal) vestibular nucleus

Py Pyramid

LCSp Lateral corticospinal tract

RNu Red nucleus

LRNu Lateral reticular nucleus

RuSp Rubrospinal tract

LVNu Lateral vestibular nucleus

SC Superior colliculus

LVesSp Lateral vestibulospinal tract

SVNu Superior vestibular nucleus

ML Medial lemniscus

TecSp Tectospinal tract

MLF Medial longitudinal fasciculus

VesSp Vestibulospinal tracts

Review of Blood Supply to RNu, Vestibular Nuclei, MFL

and RuSp, and Vestibulospinal Tracts in Cords

STRUCTURES

ARTERIES

RNu

medial branches of posterior cerebral and posterior communicating

plus some from short circumferential branches of posterior cerebral

(see Figure 5-27)

Vestibular Nuclei

posterior inferior cerebellar in medulla (see Figure 5-14) and long

circumferential branches in pons (see Figure 5-21)

MLF

long circumferential branches of basilar in pons (see Figure 5-21)

and anterior spinal in medulla (see Figure 5-14)

MVesSp

branches of central artery (see Figures 5-6 and 5-14)

LVesSp and RuSp

penetrating branches of arterial vasocorona plus terminal branches

of central artery (see Figure 5-6)

200

Synopsis of Functional Components, Tracts, Pathways, and Systems

Cranial Nerve Efferents (III, IV, VI, XI-AccNu, XII)

7-15

The origin and peripheral distribution of GSE fibers from the

addition, the pupil may be unaffected (pupillary sparing) or dilated and

oculomotor, trochlear, abducens, spinal accessory, and hypoglossal

fixed. Lesions in the midbrain that involve the root of the IIIrd nerve

nuclei. Also shown are GVE fibers arising from the Edinger-Westphal

and the crus cerebri give rise to a superior alternating (crossed) hemiplegia.

nucleus and the distribution of postganglionic fibers from the ciliary

This is a paralysis of most eye movement and possibly a dilated pupil

ganglion. Internuclear abducens neurons project, via the MLF, to con-

on the ipsilateral side and a contralateral hemiplegia of the extremities.

tralateral oculomotor neurons that innervate the medial rectus muscle

Damage to the MLF (as in multiple sclerosis or small vessel occlusion) be-

(internuclear ophthalmoplegia pathway).

tween the VIth and IIIrd nuclei results in internuclear ophthalmoplegia; on

Some authors specify the functional component of neurons in the

attempted lateral gaze, the opposite medial rectus muscle will not adduct.

accessory nucleus as special visceral efferent, some specify it as somatic

A lesion of the IVth nerve (frequently caused by trauma) produces diplopia

efferent, and some are noncommittal. Because, in humans, the trapez-

on downward and inward gaze (tilting the head may give some relief ), and

ius and sternocleidomastoid muscles originate from cervical somites

the eye is slightly elevated when the patient looks straight ahead.

located caudal to the last pharyngeal arch, the functional component is

Diabetes mellitus, trauma, or pontine gliomas are some causes of VIth

designated here as GSE. In addition, experiments in animals reveal that

nerve dysfunction. In these patients, the affected eye is slightly ad-

motor neurons innervating the trapezius and sternocleidomastoid

ducted, and diplopia is pronounced on attempted gaze to the lesioned

muscles are found in cervical cord levels C₁ to approximately C₆.

side. Damage in the caudal and medial pons may involve the fibers of

Neurotransmitters: Acetylcholine

(and probably calcitonin

the VIth nerve and the adjacent corticospinal fibers in the basilar pons,

gene-related peptide, CGRP) is found in the motor neurons of cranial

giving rise to a middle alternating (crossed ) hemiplegia. The deficits are an

nerve nuclei and in their peripheral endings. This substance is also

ipsilateral paralysis of the lateral rectus muscle and a contralateral

found in cells of the Edinger-Westphal nucleus and the ciliary ganglion.

hemiplegia of the extremities. The XIth nerve may be damaged cen-

Clinical Correlations: Myasthenia gravis (MG) is a disease caused

trally (as in syringobulbia or amyotrophic lateral sclerosis) or at the jugular

by autoantibodies that may directly block nicotinic acetylcholine

foramen with resultant paralysis of the ipsilateral sternocleidomastoid

receptors or damage the postsynaptic membrane (via complement me-

and upper parts of the trapezius muscle.

diated lysis) thereby reducing the number of viable receptor sites. Oc-

Central injury to the XIIth nucleus or fibers (as in the medial

ular movement disorders (diplopia, ptosis) are seen first in approxi-

medullary syndrome or in syringobulbia) or to its peripheral parts (as in

mately 50% of patients and are present in approximately 85% of all

polyneuropathy or tumors) results in deviation of the tongue toward the

MG patients. Movements of the neck and tongue may also be impaired,

lesioned side on attempted protrusion. A lesion in the medial aspects

with the latter contributing to dysphagia and dysarthria.

of the medulla will give rise to an inferior alternating (crossed ) hemiplegia.

Lesions of the IIIrd nerve (as in the Weber syndrome or in carotid cav-

This is characterized by a paralysis of the ipsilateral side of the tongue

ernous aneurysms) may result in 1) ptosis, 2) lateral and downward devi-

(XIIth root damage) and contralateral hemiplegia of the extremities

ation of the eye, and 3) diplopia (except on ipsilateral lateral gaze). In

(damage to corticospinal fibers in the pyramid).

Abbreviations

AbdNr Abducens nerve

OcNu Oculomotor nucleus

AbdNu Abducens nucleus

PO Principal olivary nucleus

AccNr Accessory nerve

Py Pyramid

AccNu Accessory nucleus (spinal accessory nu.)

RNu Red nucleus

BP Basilar pons

SC Superior colliculus

CC Crus cerebri

SCP,Dec Superior cerebellar peduncle, decussation

EWNu Edinger-Westphal nucleus

TroDec Trochlear decussation

FacCol Facial colliculus

TroNr Trochlear nerve

HyNr Hypoglossal nerve

TroNu Trochlear nucleus

HyNu Hypoglossal nucleus

ML Medial lemniscus

Ganglion

MLF Medial longitudinal fasciculus

Ciliary

OcNr Oculomotor nerve

Review of Blood Supply to OcNu, TroNu, AbdNu and HyNu,

and the Internal Course of their Fibers

STRUCTURES

ARTERIES

OcNu and Fibers

medial branches of posterior cerebral and posterior

communicating (see Figure 5-27)

TroNu

paramedian branches of basilar bifurcation (see Figure 5-27)

AbdNu

long circumferential branches of basilar (see Figure 5-21)

Abducens Fibers in BP

paramedian branches of basilar (see Figure 5-21)

HyNu and Fibers

anterior spinal (see Figure 5-14)

202

Synopsis of Functional Components, Tracts, Pathways, and Systems

Cranial Nerve Efferents (V, VII, IX, and X)

7-16

The origin and peripheral distribution of fibers arising from

viates to the lesioned side when closed);, and 3) loss of the afferent limb

the SVE motor nuclei of the trigeminal, facial, and glossopharyngeal and

of the corneal reflex. If especially large, a vestibular schwannoma may

vagus (via the nucleus ambiguus) nerves. Also shown are the origin of

compress the trigeminal nerve root and result in a hemifacial sensory

GVE preganglionic parasympathetic fibers from the superior (to facial

loss that may include the oral cavity. Trigeminal neuralgia (tic douloureux)

nerve) and inferior (to glossopharyngeal nerve) salivatory nuclei and

is an intense, sudden, intermittent pain emanating from the area of the

from the dorsal motor vagal nucleus. Their respective ganglia are indi-

cheek, oral cavity, or adjacent parts of the nose (distribution of V₂ or

cated as well as the structures innervated by postganglionic fibers aris-

V₃, see also Figure 7-7 on page 184).

ing from each. The SVE functional component specifies cranial nerve

Tumors (such as chordoma or vestibular schwannoma), trauma, or

motor nuclei that innervate head muscles that arose, embryologically,

meningitis may damage the VIIth nerve, resulting in 1) an ipsilateral fa-

from pharyngeal arches. Muscles innervated by the trigeminal nerve (V)

cial palsy (or Bell palsy); 2) loss of taste from the ipsilateral two-thirds

come from the 1st arch, those served by the facial nerve (VII) from the

of the tongue; and (3) decreased secretion from the ipsilateral lacrimal,

2nd arch; the stylopharyngeal muscle originates from the 3rd arch and

nasal, and sublingual and submandibular glands. Injury distal to the

is innervated by the glossopharyngeal nerve (IX), and the muscles de-

chorda tympani produces only an ipsilateral facial palsy. A paralysis of

rived from the 4th arch are served by the vagus nerve (X).

the muscles on one side of the face with no paralysis of the extremities

Neurotransmitters: The transmitter found in the cells of cra-

is a facial hemiplegia. On the other hand, intermittent and involuntary

nial nerve motor nuclei, and in their peripheral endings, is acetyl-

contraction of the facial muscles is called hemifacial spasm. One cause is

choline; CGRP is also colocalized in these motor neurons. This

compression of the facial root by an artery, most commonly a loop of

substance is also present in preganglionic and postganglionic para-

the anterior inferior cerebellar artery or its branches. These patients

sympathetic neurons.

may also have deficits (vertigo, tinnitus, hearing loss) suggesting involve-

Clinical Correlations: Patients with myasthenia gravis frequently

ment of the adjacent vestibulocochlear nerve.

have oropharyngeal symptoms and complications that result in

Because of their common origin from NuAm, adjacent exit from the

dysarthria, and dysphagia. These individuals have difficulty chewing and

medulla, and passage through the jugular foramen, the IXth and Xth

swallowing, their jaw may hang open, and the mobility of facial mus-

nerves may be damaged together (as in amyotrophic lateral sclerosis or in

cles is decreased. Imparied hearing (weakness of tensor tympani) and

syringobulbia). The results are dysarthria, dysphagia, dyspnea, loss of taste

hyperacusis (weakness of stapedius) may also be present.

from the ipsilateral caudal tongue, and loss of the gag reflex, but no sig-

Lesions of the Vth nerve (as in meningiomas or trauma) result in 1) loss

nificant autonomic deficits. Bilateral lesions of the Xth nerve are life-

of pain, temperature, and touch on the ipsilateral face and in the oral

threatening because of the resultant total paralysis (and closure) of the

and nasal cavities; 2) paralysis of ipsilateral masticatory muscles ( jaw de-

muscles in the vocal folds (vocalis muscle).

Abbreviations

AbdNu Abducens nucleus

SpTNu Spinal trigeminal nucleus

ALS Anterolateral system

SpTTr Spinal trigeminal tract

BP Basilar pons

SSNu Superior salivatory nucleus

DVagNu Dorsal motor nucleus of vagus

TecSp Tectospinal tract

FacNr Facial nerve

TriMoNu Trigeminal motor nucleus

FacNu Facial nucleus

TriNr Trigeminal nerve

GINr Glossopharyngeal nerve

VagNr Vagus nerve

HyNu Hypoglossal nucleus

ISNu Inferior salivatory nucleus

Ganglia

MesNu Mesencephalic nucleus

Pterygopalatine

ML Medial lemniscus

Submandibular

MLF Medial longitudinal fasciculus

Otic

NuAm Nucleus ambiguus

Terminal and/or intramural

PSNu Principal (chief ) sensory nucleus

Review of Blood Supply to TriMoNu, FacNu, DMNu and NuAm,

and the Internal Course of Their Fibers

STRUCTURES

ARTERIES

TriMoNu and Trigeminal Root long circumferential branches of basilar (see Figure 5-21)

FacNu and Internal Genu

long circumferential branches of basilar (see Figure 5-21)

DMNu and NuAm

branches of vertebral and posterior inferior cerebellar

(see Figure 5-14)

204

Synopsis of Functional Components, Tracts, Pathways, and Systems

Spinocerebellar Tracts

7-17

The origin, course, and distribution pattern of fibers to the

bellar fibers, in their mossy fiber terminals in the cerebellar cortex, and

cerebellar cortex and nuclei from the spinal cord (posterior [dorsal]

in their collateral branches that innervate the cerebellar nuclei.

and anterior [ventral] spinocerebellar tracts, rostral spinocerebellar

Clinical Correlations: Lesions, or tumors, that selectively dam-

fibers) and from the external cuneate nucleus

(cuneocerebellar

age only spinocerebellar fibers are rarely, if ever, seen in humans. The

fibers). Also illustrated is the somatotopy of those fibers originating

ataxia one might expect to see in patients with a spinal cord hemisection

from the spinal cord. These fibers enter the cerebellum via the resti-

(as in the Brown-Sequard syndrome) is masked by the hemiplegia resulting

form body, the larger portion of the inferior cerebellar peduncle, or

from the concomitant damage to lateral corticospinal (and other) fibers.

in relationship to the superior cerebellar peduncle. After these fibers

Friedreich ataxia (hereditary spinal ataxia) is an autosomal recessive dis-

enter the cerebellum, collaterals are given off to the cerebellar nuclei

order the symptoms of which usually appear between 8 and 15 years

while the parent axons of spinocerebellar and cuneocerebellar fibers

of age. There is degeneration of anterior and posterior spinocerebellar

pass on to the cortex, where they end as mossy fibers in the graunular

tracts plus the posterior columns and corticospinal tracts. Degenera-

layer. Although not shown here, there are important ascending spinal

tive changes are also seen in Purkinje cells in the cerebellum, in poste-

projections to the medial and dorsal accessory nuclei of the inferior

rior root ganglion cells, in neurons of the Clarke column, and in some

olivary complex (spino-olivary fibers). The accessory olivary nuclei

nuclei of the pons and medulla. The axial and appendicular ataxia seen

(as well as the principal olivary nucleus) project to the cerebellar cor-

in these patients correlates partially with the spinocerebellar degener-

tex and send collaterals into the nuclei (see Figure 7-18 on page 206).

ation and also partially with proprioceptive losses via the degeneration

Neurotransmitters: Glutamate (

) is found in some spinocere- of posterior column fibers.

Abbreviations

ACNu Accessory (external or lateral) cuneate

PSCT Posterior (dorsal) spinocerebellar tract

nucleus

PSNu Principal (chief ) sensory nucleus of

ALS Anterolateral system

trigeminal nerve

AMV Anterior medullary velum

Py Pyramid

ASCT Anterior (ventral) spinocerebellar tract

RB Restiform body

Cbl Cerebellum

RSCF Rostral spinocerebellar fibers

CblNu Cerebellar nuclei

RuSp Rubrospinal tract

CCblF Cuneocerebellar fibers

S Sacral representation

DNuC Dorsal nucleus of Clarke

SBC Spinal border cells

FNL Flocculonodular lobe

SCP Superior cerebellar peduncle

IZ Intermediate zone

SpTNu Spinal trigeminal nucleus

L Lumbar representation

SpTTr Spinal trigeminal tract

MesNu Mesencephalic nucleus

T Thoracic representation

ML Medial lemniscus

TriMoNu Trigeminal motor nucleus

PRG Posterior (dorsal) root ganglion

VesNu Vestibular nuclei

Review of Blood Supply to Spinal Cord Grey Matter,

Spinocerebellar Tracts, RB, and SCP

STRUCTURES

ARTERIES

Spinal Cord Grey

branches of central artery (see Figure 5-6)

PSCT and ASCT in Cord

penetrating branches of arterial vasocorona (see Figure 5-6)

posterior inferior cerebellar (See Figure 5-14)

SCP

long circumferential branches of basilar and superior

cerebellar (see Figure 5-21)

Cerebellum

posterior and anterior inferior cerebellar and superior

cerebellar

206

Synopsis of Functional Components, Tracts, Pathways, and Systems

Pontocerebellar, Reticulocerebellar, Olivocerebellar, Ceruleocerebellar,

Hypothalamocerebellar, and Raphecerebellar Fibers

7-18

Afferent fibers to the cerebellum from selected brainstem ar-

ticotropin (

)-releasing factor are present in many olivocerebellar

eas and the organization of corticopontine fibers in the internal capsule

fibers. Ceruleocerebellar fibers contain noradrenalin, histamine is

and crus cerebri as shown here. The cerebellar peduncles are also indi-

found in hypothalamocerebellar fibers, and some reticulocerebellar

cated. Pontocerebellar axons are mainly crossed, reticulocerebellar

fibers contain enkephalin. Serotonergic fibers to the cerebellum arise

fibers may be bilateral (from RetTegNu) or mainly uncrossed (from

from neurons found in medial areas of the reticular formation (open

LRNu and PRNu), and olivocerebellar fibers (OCblF) are exclusively

cell in Figure 7-18) and, most likely, from some cells in the adjacent

crossed. Raphecerebellar, hypothalamocerebellar, and ceruleocerebel-

raphe nuclei.

lar fibers are, to varying degrees, bilateral projections. Although all af-

Clinical Correlations: Common symptoms seen in patients with

ferent fibers to the cerebellum give rise to collaterals to the cerebellar

lesions involving nuclei and tracts that project to the cerebellum are

nuclei, those from pontocerebellar axons are relatively small, having

ataxia (of trunk or limbs), an ataxic gait, dysarthria, dysphagia, and dis-

comparatively small diameters. Olivocerebellar axons end as climbing

orders of eye movement such as nystagmus. These deficits are seen in

fibers, reticulocerebellar and pontocerebellar fibers as mossy fibers, and

some hereditary diseases (such as olivopontocerebellar degeneration, ataxia

hypothalamocerebellar and ceruleocerebellar axons end in all cortical

telangiectasia, or hereditary cerebellar ataxia), in tumors

(brainstem

layers. These latter fibers have been called multilayered fibers in the lit-

gliomas), in vascular diseases (lateral pontine syndrome), or in other con-

erature because they branch in all layers of the cerebellar cortex.

ditions such as alcoholic cerebellar degeneration or pontine hemorrhages

Neurotransmitters: Glutamate (

) is found in corticopontine

(see Figure 7-19 on page 208 for more information on cerebellar le-

projections and in most pontocerebellar fibers. Aspartate (

) and cor- sions).

Abbreviations

AntLb Anterior limb of internal capsule

PonNu Pontine nuclei

CblNu Cerebellar nuclei

PO Principal olivary nucleus

CerCblF Ceruleocerebellar fibers

PPon Parietopontine fibers

CPonF Cerebropontine fibers

PRNu Paramedian reticular nuclei

CSp Corticospinal fibers

Py Pyramid

DAO Dorsal accessory olivary nucleus

RB Restiform body

FPon Frontopontine fibers

RCblF Reticulocerebellar fibers

Hyth Hypothalamus

RetLenLb Retrolenticular limb of internal capsule

HythCblF Hypothalamocerebellar fibers

RNu Red nucleus

IC Internal capsule

RetTegNu Reticulotegmental nucleus

LoCer Nucleus (locus) ceruleus

SCP Superior cerebellar peduncle

LRNu Lateral reticular nucleus

SubLenLb Sublenticular limb of internal capsule

MAO Medial accessory olivary nucleus

SN Substantia nigra

MCP Middle cerebellar peduncle

TPon Temporopontine fibers

ML Medial lemniscus

NuRa Raphe nuclei

Number Key

OCblF Olivocerebellar fibers

Nucleus raphe, pontis

OPon Occipitopontine fibers

Nucleus raphe, magnus

PCbIF Pontocerebellar fibers

Raphecerebellar fibers

PostLb Posterior limb of internal capsule

Review of Blood Supply to Precerebellar Relay Nuclei in Pons

and Medulla, MCP, and RB

STRUCTURES

ARTERIES

Pontine Tegmemtum

long circumferential branches of basilar plus some from superior

cerebellar (see Figure 5-21)

Basilar Pons

paramedian and short circumferential branches of basilar (See

Figure 5-21)

Medulla RetF and IO branches of vertebral and posterior inferior cerebellar (see

Figure 5-14)

MCP

long circumferential branches of basilar and branches of anterior

inferior and superior cerebellar (see Figure 5-21)

posterior inferior cerebellar (see Figure 5-14)

208

Synopsis of Functional Components, Tracts, Pathways, and Systems

Cerebellar Cortioconuclear, Nucleocortical, and Corticovestibular Fibers

7-19

Cerebellar corticonuclear fibers arise from all regions of the

Lesions involving midline structures (vermal cortex, fastigial nu-

cortex and terminate in an orderly (mediolateral and rostrocaudal) se-

clei) and/or the flocculonodular lobe result in truncal ataxia (titubation

quence in the ipsilateral cerebellar nuclei. For example, corticonuclear

or tremor), nystagmus, and head tilting. These patients may also have a

fibers from the vermal cortex terminate in the fastigial nucleus, those

wide-based (cerebellar) gait, are unable to walk in tandem (heel to toe),

from the intermediate cortex terminate in the emboliform and globo-

and may be unable to walk on their heels or on their toes. Generally,

sus nuclei, and those from the lateral cortex terminate in the dentate nu-

midline lesions result in bilateral motor deficits affecting axial and

cleus. Also, cerebellar corticonuclear fibers from the anterior lobe typ-

proximal limb musculature.

ically terminate in more rostral regions of these nuclei while those from

Damage to the intermediate and lateral cortices and the globose,

the posterior lobe terminate more caudally. Cerebellar corticovestibu-

emboliform, and dentate nuclei results in various combinations of the

lar fibers originate primarily from the vermis and flocculonodular lobe,

following deficits: dysarthria, dysmetria (hypometria, hypermetria), dysdi-

exit the cerebellum via the juxtarestiform body, and end in the ipsilat-

adochokinesia, tremor (static, kinetic, intention), rebound phenomenon, un-

eral vestibular nuclei. These projections arise from Purkinje cells.

steady and wide-based (cerebellar) gait, and nystagmus. One of the more

Nucleocortical processes originate from cerebellar nuclear neurons

commonly observed deficits in patients with cerebellar lesions is an in-

and pass to the overlying cortex in a pattern that basically reciprocates

tention tremor, which is best seen in the finger-nose test. The finger-to-fin-

that of the corticonuclear projection; they end as mossy fibers. Some

ger test is also used to demonstrate an intention tremor and to assess

nucleocortical fibers are collaterals of cerebellar efferent axons. The

cerebellar function. The heel-to-shin test will show dysmetria in the lower

cerebellar cortex may influence the activity of lower motor neurons

extremity. If the heel-to-shin test is normal in a patient with his/her

through, for example, the cerebellovestibular-vestibulospinal route.

eyes open, the cerebellum is intact. If this test is repeated in the same

Neurotransmitters: Gamma-aminobutyric acid (GABA) (

) is

patient with eyes closed and is abnormal, this would suggest a lesion in

found in Purkinje cells and is the principal transmitter substance pres-

the posterior column-medial lemniscus system.

ent in cerebellar corticonuclear and corticovestibular projections.

Cerebellar damage in intermittent and lateral areas (nuclei or cor-

However, taurine (

) and motilin (

) are also found in some Purk-

tex plus nuclei) causes movement disorders on the side of the lesion

inje cells. GABA-ergic terminals are numerous in the cerebellar nuclei

with ataxia and gait problems on that side; the patient may tend to fall

and vestibular complex. Some of the glutamate-containing mossy

toward the side of the lesion. This is because the cerebellar nuclei pro-

fibers in the cerebellar cortex represent the endings of nucleocortical

ject to the contralateral thalamus, which projects to the motor cortex

fibers that originate from cells in the cerebellar nuclei.

on the same side, which projects to the contralateral side of the spinal

Clinical Correlations: Numerous disease entities can result in

cord via the corticospinal tract. Other circuits

(cerebellorubal-

cerebellar dysfunction including viral infections (echovirus), hereditary

rubospinal) and feedback loops (cerebelloolivary-olivocerebellar) fol-

diseases (see Figure 7-18), trauma, tumors (glioma, medulloblastoma),

low similar routes. Consequently, the motor expression of unilateral

occlusion of cerebellar arteries (cerebellar stroke), arteriovenous malfor-

cerebellar damage is toward the lesioned side because of these doubly

mation of cerebellar vessels, developmental errors (such as the Dandy-

crossed pathways.

Walker syndrome or the Arnold-Chiari deformity), or the intake of toxins.

Lesions of cerebellar efferent fibers, after they cross the midline in

Usually, damage to only the cortex results in little or no dysfunction

the decussation of the superior cerebellar peduncle, will give rise to

unless the lesion is quite large or causes an increase in intracranial pres-

motor deficits on the side of the body (excluding the head) contralat-

sure. However, lesions involving both the cortex and nuclei, or only

eral to the lesion. This is seen in midbrain lesions such as the Claude syn-

the nuclei, will produce obvious cerebellar signs.

drome.

Abbreviations

CorNu Corticonuclear fibers

MVesSp Medial vestibulospinal tract

CorVes Corticovestibular fibers

MVNU Medial vestibular nucleus

Flo Flocculus

NL, par Lateral cerebellar nucleus, parvocellular

IC Intermediate cortex

region

InfVesNu Inferior (spinal) vestibular nucleus

NM, par Medial cerebellar nucleus,

JRB Juxtarestiform body

parvocellular region

LC Lateral cortex

NuCor Nucleocortical fibers

LVesSp Lateral vestibulospinal tract

SVNu Superior vestibular nucleus

LVNu Lateral vestibular nucleus

VC Vermal cortex

MLF Medial longitudinal fasciculus

Review of Blood Supply to Cerebellum and Vestibular Nuclei

STRUCTURES

ARTERIES

Cerebellar Cortex

branches of posterior and anterior inferior cerebellar and superior

cerebellar

Cerebellar Nuclei

anterior inferior cerebellar and superior cerebellar

Vestibular Nuclei

posterior inferior cerebellar in medulla, long circumferential

branches of basilar in pons

210

Synopsis of Functional Components, Tracts, Pathways, and Systems

Cerebellar Efferent Fibers

7-20

The origin, course, topography, and general distribution of

belloreticular-reticulospinal,

3) cerebellothalamic-thalamocortical-

fibers arising in the cerebellar nuclei. Cerebellofugal fibers project to

corticospinal, and others. In addition, some direct cerebellospinal

several thalamic areas (VL and VA), to intralaminar relay nuclei in ad-

fibers arise in the fastigial nucleus as well as in the interposed nuclei.

dition to the centromedian, and to a number of midbrain, pontine, and

Neurotransmitters: Many cells in the cerebellar nuclei contain

medullary targets. Most of the latter nuclei project back to the cere-

glutamate (

), aspartate (

), or gamma-aminobutyric acid (

). Glu-

bellum (e.g., reticulocerebellar, pontocerebellar), some in a highly or-

tamate and aspartate are found in cerebellorubral and cerebellothala-

ganized manner. For example, cerebello-olivary fibers from the den-

mic fibers, whereas some GABA-containing cells give rise to cerebel-

tate nucleus (DNu) project to the principal olivary nucleus (PO), and

lopontine and cerebello-olivary fibers. Some cerebelloreticular

neurons of the PO send their axons back to the lateral cerebellar cor-

projections may also contain GABA.

tex, with collaterals going to the DNu.

Clinical Correlations: Lesions of the cerebellar nuclei result in a

The cerebellar nuclei can influence motor activity through, as ex-

range of motor deficits depending on the location of the injury. Many

amples, the following routes: 1) cerebellorubral-rubrospinal, 2) cere- of these are described in Figure 7-19 on page 208.

Abbreviations

ALS

Anterolateral system

OcNu

Oculomotor nucleus

AMV

Anterior medullary velum

Principal olivary nucleus

Basilar pons

PonNu

Pontine nuclei

CblOl

Cerebello-olivary fibers

RetForm

Reticular formation

CblTh

Cerebellothalamic fibers

RNu

Red nucleus

CblRu

Cerebellorubral fibers

RuSp

Rubrospinal tract

Crus cerebri

Superior colliculus

CeGy

Central grey (periaqueductal grey)

SCP

Superior cerebellar peduncle

Centromedian nucleus of thalamus

SCP, Dec

Superior cerebellar peduncle, decussation

CSp

Corticospinal fibers

Substantia nigra

DAO

Dorsal accessory olivary nucleus

SVNu

Superior vestibular nucleus

DNu

Dentate nucleus (lateral cerebellar nucleus)

ThCor

Thalamocortical fibers

ENu

Emboliform nucleus (anterior interposed

ThFas

Thalamic fasciculus

cerebellar nucleus)

TriMoNu

Trigeminal motor nucleus

EWNu

Edinger-Westphal nucleus

Ventral lateral nucleus of thalamus

FNu

Fastigial nucleus (medial cerebellar nucleus)

VPL

Ventral posterolateral nucleus of thalamus

GNu

Globose nucleus (posterior interposed

VSCT

Ventral spinocerebellar tract

cerebellar nucleus)

Zona incerta

Inferior colliculus

InfVNu

Inferior (spinal) vestibular nucleus

Number Key

INu

Interstitial nucleus

Ascending projections to superior

LRNu

Lateral reticular nucleus

colliculus, and possibly ventral lateral and

LVNu

Lateral vestibular nucleus

ventromedial thalamic nuclei

MAO

Medial accessory olivary nucleus

Descending crossed fibers from superior

Medial lemniscus

cerebellar peduncle

MLF

Medial longitudinal fasciculus

Uncinate fasciculus (of Russell)

MVNu

Medial vestibular nucleus

Juxtarestiform body to vestibular nuclei

NuDark

Nucleus of Darkschewitsch

Reticular formation

Review of Blood Supply to Cerebellar Nuclei and

Their Principal Efferent Pathways

STRUCTURES

ARTERIES

Cerebellar Nuclei

anterior inferior cerebellar and superior cerebellar

SCP

long circumferential branches of basilar and superior cerebellar

(see Figure 5-21)

Midbrain Tegmemtum

paramedian branches of basilar bifurcation, short circumferential

(RNu, CblTh,

branches of posterior cerebral, branches of superior cerebellar

CblRu, OcNu)

(see Figure 5-27)

VPL, CM, VL, VA

thalamogeniculate branches of posterior cerebral, thalamo-

perforating branches of the posteromedial group of posterior

cerebral (see Figure 5-38)

lateral striate branches of middle cerebral (see Figure 5-38)

214

Synopsis of Functional Components, Tracts, Pathways, and Systems

Striatal Connections

7-22

The origin, course, and distribution of afferent fibers to, and

enkephalinergic cells in the neostriatum (primarily the caudate) and

efferent projections from, the neostriatum. These projections are ex-

cell loss in the cerebral cortex. Loss of neostriatal cell terminals in the

tensive, complex, and in large part, topographically organized; only

lateral and medial segments of the globus pallidus correlate, respec-

their general patterns are summarized here. Afferents to the caudate

tively, with the development of choreiform movements and later with

and putamen originate from the cerebral cortex (corticostriate fibers),

rigidity and dystonia. Loss of cortical neurons correlate, respectively,

from several of the intralaminar thalamic nuclei (thalamostriate), from

with personality changes and eventual dementia. Huntington chorea is

the substantia nigra-pars compacta (nigrostriate), and from some of the

rapid, unpredictable, and may affect muscles of the extremities, face,

raphe nuclei. Neostriatal cells send axons into the globus pallidus (pa-

and trunk; abnormal movements seem to flow through the body. Pa-

leostriatum) as striopallidal fibers and into the substantia nigra pars

tients commonly attempt to mask the abnormal movement by trying

reticulata as a strionigral projection.

to make it appear to be part of an intended movement (parakinesia).

Neurotransmitters: Glutamate (

) is found in corticostriate

Symptoms in Wilson disease (hepatolenticular degeneration) appear in

fibers, and serotonin is found in raphestriatal fibers from the nucleus

persons between 10 to 20 years of age. Copper accumulates in the basal

raphe dorsalis. Four neuroactive substances are associated with striatal

nuclei (ganglia) and the frontal cortex, with resultant spongy degener-

efferent fibers, these being gamma-aminobutyric acid (GABA)(

ation in the putamen and cortex. These patients may show athetoid

dynorphin, enkephalin(

), and substance P(

). Enkephalinergic and

movements, rigidity and spasticity, dysarthria, dysphagia, contractures, and

GABA-ergic striopallidal projections are numerous to the lateral pal-

tremor. A unique movement of the hand and/or upper extremity in

lidum (origin of pallidosubthalamic fibers), while dynorphin-contain-

these patients is called a flapping tremor (asterixis) sometimes described

ing terminals are more concentrated in its medial segment (source of

as a wing-beating tremor. Copper can also be seen in the cornea

pallidothalamic fibers). Enkephalin and GABA are also present in stri-

(Kayser-Fleischer ring) in these patients.

onigral projections to the pars reticulata. Because substance P and

In Parkinson disease (onset at 50 to 60 years of age), there is a pro-

GABA are found in striopallidal and strionigral fibers, some of the for-

gressive loss of dopaminergic cells in the substantia nigra-pars com-

mer may be collaterals of the latter. Dopamine is present in nigrostri-

pacta, of their terminals in the caudate and putamen, and of their den-

atal projection neurons and in their terminals in the neostriatum.

drites that extend into the substantia nigra-pars reticulata. Patients

Clinical Correlations: Degenerative changes and neuron loss in

with Parkinson disease characteristically show a resting tremor (pill-

the caudate nucleus and putamen result in movement disorders. Ex-

rolling), rigidity (cog wheel or lead pipe), and bradykinesia or hypokinesia.

amples are seen in Sydenham chorea (rheumatic chorea), Huntington disease

The slowness of movement may also be expressed in speech (dysarthria,

(a dominantly inherited disease), and Wilson disease (a genetic error in

hypophonia, tachyphonia) and in writing (micrographia). These patients

the patient’s ability to metabolize copper). In persons with Parkinson

have a distinct stooped flexed posture and a festinating gait. Behavioral

disease, a loss of the dopamine-containing cells in the pars compacta of

changes are also seen. Parkinson disease and Huntington disease are

the substantia nigra and of their nigrostriatal terminals in the caudate

progressive neurodegenerative disorders.

nucleus and putamen occurs.

Dystonia, a movement disorder seen in some patients with basal nu-

Sydenham chorea is a disease usually seen in children between 5 and

clei disease, is characterized by increased/sustained muscle contrac-

15 years of age, resulting from infection with hemolytic streptococcus.

tions that cause twisting of the trunk or extremities resulting in abnor-

The choreiform movements are brisk and flowing, irregular, and may in-

mal posture. These patients may also have unusual and repetitive

volve muscles of the limbs, face, oral cavity, and trunk. Dystonia may

movements of the extremities or of the neck (cervical dystonia or spas-

be seen; muscle weakness is common. In most patients, the disease re-

modic torticollis). Dystonia may be an inherited progressive disease or

solves following successful treatment of the infection.

have other causes and may be seen in children or young adults. The

Huntington disease is a progressive genetic disorder the symptoms of

symptoms may initially appear during movements or when talking but

which appear at 35 to 45 years of age. There is loss of GABA-ergic and

in later stages may be present at rest.

Abbreviations

CaNu Caudate nucleus

SNpc Substantia nigra, pars compacta

CorSt Corticostriate fibers

SNpr Substantia nigra, pars reticulata

GPL Globus pallidus, lateral segment

StNig Striatonigral fibers

GPM Globus pallidus, medial segment

StPal Striatopallidal fibers

NigSt Nigrostriatal fibers

SThNu Subthalamic nucleus

Put Putamen

ThSt Thalamostriatal fibers

RaNu Raphe nuclei

ZI Zona incerta

RaSt Raphestriatal fibers

Review of Blood Supply to Caudate, Putamen, SN, CC, and IC

STRUCTURES

ARTERIES

Caudate, Putamen and IC

medial striate a. for head of caudate and lateral striate

branches of middle cerebral for Put and IC (see Figure

5-38)

SN and CC

paramedian branches of basilar bifurcation, short

circumferential branches of posterior cerebral and some

from superior cerebellar (see Figure 5-27)

216

Synopsis of Functional Components, Tracts, Pathways, and Systems

Pallidal Efferents and Nigral Connections

7-23

The origin, course, and distribution of efferent projections

rons, which give rise to nigrostriatal, nigroamygdaloid, and several

of the globus pallidus (upper illustration), and connections of the sub-

other projections; GABA in pars reticulata cells, which give rise to ni-

stantia nigra (lower drawing) that were not shown in relation to the

grocollicular and nigrothalamic fibers; and glycine in some local circuit

pallidum or in Figure 7-22 on page 215. The ansa lenticularis (dashed

nigral neurons. Glutamate (

) is found in corticonigral fibers, and

line) arches around the internal capsule and passes caudally to join in

serotonin (

) is associated with raphenigral fibers; these latter fibers

the formation of the thalamic fasciculus. Pallidosubthalamic fibers orig-

originate primarily from the nucleus raphe dorsalis.

inate primarily from the lateral pallidal segment, but pallidothalamic

The dopaminergic projections to the frontal cortex, shown here as

projections, via the ansa lenticularis and lenticular fasciculus, arise

arising only from SNpc, originates from this cell group as well as from

mainly from its medial segment. The substantia nigra has extensive

the immediately adjacent ventral tegmental area. Excessive activity in

connections, the clinically most important being the dopaminergic ni-

neurons comprising this projection may play a partial role in schizo-

grostriatal fibers. The globus pallidus influences motor activity by way

phrenia.

of pallidothalamic-thalamocortical-corticospinal (and corticonuclear

Clinical Correlation: Movement disorders associated with le-

[corticobulbar]) pathways.

sions in the neostriatum and substantia nigra are reviewed in Figure

Neurotransmitters: Gamma-aminobutyric acid (

)-containing

7-22 on page 214. Hemorrhage into, the occlusion of vessels serving

cells in the globus pallidus give rise to pallidonigral projections, which

or a tumor within, the subthalamic nucleus will result in violent flail-

end primarily in the substantia nigra-pars reticulata. Although GABA

ing movements of the extremities, a condition called hemiballismus.

is also found in some subthalamopallidal axons, this latter projection

Hemiballistic movements are seen contralateral to the lesion because

contains many glutaminergic (

) fibers. Dopamine-containing, GABA

the motor expression of this lesion is through the corticospinal tract.

(

)-containing, and glycine (

)-containing cells are present in the

Lesions confined to the globus pallidus, as in hemorrhage of lenticu-

substantia nigra. Of these, dopamine is found in pars compacta neu-

lostriate arteries, may result in hypokinesia and rigidity without tremor.

Abbreviations

AmyNig Amygdalonigral fibers

PedPonNu Pedunculopontine nucleus

AmyNu Amygdaloid nucleus (complex)

Put Putamen

AnLent Ansa lenticularis

RaNu Raphe nuclei

CaNu Caudate nucleus

SC Superior colliculus

CM Centromedian nucleus of thalamus

SNpc Substantia nigra, pars compacta

CorNig Corticonigral fibers

SNpr Substantia nigra, pars reticulata

CSp Corticospinal fibers

SThFas Subthalamic fasciculus

GPL Globus pallidus, lateral segment

SThNig Subthalamonigral fibers

GPM Globus pallidus, medial segment

SthNu Subthalamic nucleus

LenFas Lenticular fasciculus (H₂)

ThCor Thalamocortical fibers

NigAmy Nigroamygdaloid fibers

ThFas Thalamic fasciculus (H₁)

NigCol Nigrocollicular fibers

VA Ventral anterior nucleus of thalamus

NigTec Nigrotectal fibers

VL Ventral lateral nucleus of thalamus

NigSTh Nigrosubthalamic fibers

VM Ventromedial nucleus of thalamus

NigTh Nigrothalamic fibers

ZI Zona incerta

PalNig Pallidonigral fibers

Review of Blood Supply to Pallidum, Subthalamic Area, and SN

STRUCTURES

ARTERIES

GPM/GPL lateral striate branches of middle cerebral and branches of anterior choroidal

(see Figure 5-38)

SThNu

posteromedial branches of posterior cerebral and posterior communicating

(see Figure 5-38)

branches of basilar bifurcation, medial branches of posterior cerebral and

posterior communicating, short circumferential branches of posterior

cerebral (see Figure 5-27)

220

Synopsis of Functional Components, Tracts, Pathways, and Systems

Pupillary Pathways

7-25

The origin, course, and distribution of fibers involved in the

ducing a bitemporal hemianopsia) or the uncrossed fibers in the right (or

pathway for the pupillary light reflex. In addition, the pathway for sym-

left) side of the optic chiasm. These lateral lesions produce a right (or

pathetic innervation of the dilator muscle of the iris is also depicted. The

left) nasal hemianopsia.

pathway from the midbrain reticular formation to the intermediolateral

Optic (geniculocalcarine) radiations (see Figures 7-26 and 7-27 on

cell column may also have a multisynaptic component, with relay sta-

pages 222 and 223) may pass directly caudal to the upper lip (cuneus)

tions in the pontine and medullary reticular formations. Postganglionic

of the calcarine sulcus or follow an arching route (the Meyer, or Meyer-

sympathetic fibers to the head originate from the superior cervical gan-

Archambault loop) through the temporal lobe to the lower bank (lingual

glion. Although not shown, descending projections to the intermedio-

gyrus) of the calcarine sulcus. Temporal lobe lesions involving the

lateral cell column also originate from various hypothalamic areas and

Meyer-Archambault loop, or involving fibers entering the lingual

nuclei (hypothalamospinal fibers), some of which receive retinal input.

gyrus, can produce a homonymous superior quadrantanopia. A homonymous

Neurotransmitters: Acetylcholine is the transmitter found in

inferior quandrantanopia is seen in patients with damage to upper (pari-

the preganglionic and postganglionic autonomic fibers shown in this il-

etal) parts of the geniculocalcarine radiations or to these fibers as they

lustration. In addition, N-acetylaspartylglutamate is present in some

enter the cuneus.

retinal ganglion cells (retinogeniculate projections).

Damage to the visual cortex adjacent to the calcarine sulcus (distal

Clinical Correlations: Total or partial blindness in one or both

posterior cerebral artery occlusion) results in a right (or left) homony-

eyes may result from a variety of causes (such as gliomas, meningiomas,

mous hemianopsia. With the exception of macular sparing, this deficit is

strokes, aneurysms, infections, and demyelinating diseases); lesions may

the same as that seen in optic tract lesions.

occur at any locus along the visual pathway. A complete lesion (for ex-

Vascular lesions (as in the lateral medullary syndrome), tumors (such

ample, a transection) of the optic nerve will result in blindness and loss

as brainstem gliomas), or syringobulbia may interrupt the descending pro-

of the pupillary light reflex (direct response) in the eye on the injured

jections from hypothalamus (hypothalamospinal fibers) and midbrain

side and a loss of the pupillary light reflex (consensual response) in the

to the intermediolateral cell column at upper thoracic levels. This may

opposite eye when shining a light in the blind eye. On the other hand, shin-

result in a Horner syndrome (ptosis, miosis, and anhidrosis) on the ipsilat-

ing a light in the normal eye will result in a pupillary light reflex (direct

eral side. The enophthalmos (a slight sinking of the eyeball into the or-

response) in that eye and a consensual response in the blind eye. A pi-

bit) frequently mentioned in relation to Horner syndrome is not really

tuitary adenoma may damage the crossing fibers in the optic chiasm (pro-

very apparent in afflicted patients.

Abbreviations

CC Crus cerebri

PoCom Posterior commissure

CilGang Ciliary ganglion

PrTecNu Pretectal nucleus

EWNu Edinger-Westphal nucleus

PulNu Pulvinar nuclear complex

ILCC Intermediolateral cell column

RetF Reticular formation

LGNu Lateral geniculate nucleus

RNu Red nucleus

MGNu Medial geniculate nucleus

SC Superior colliculus

ML Medial lemniscus

SC,Br Superior colliculus, brachium

OcNr Oculomotor nerve

SCerGang Superior cervical ganglion

OpCh Optic chiasm

SN Substantia nigra

OpNr Optic nerve

WRCom White ramus communicans

OpTr Optic tract

Review of Blood Supply to OpTr, MGB, LGB, SC,

and Midbrain Tegementum, Including PrTecNu

STRUCTURES

ARTERIES

OpTr

anterior choroidal (see Figure 5-38)

MGNu, LGNu

thalamogeniculate branches of posterior cerebral (see Figure 5-38)

SC and PrTecNu

long circumferential branches (quadrigeminal) of posterior cerebral,

posterior choroidal, and some from superior cerebellar (to SC) (see

Figures 5-27 and 5-38)

Midbrain

paramedian branches of basilar bifurcation, medial branches

Tegmentum

of posterior cerebral and posterior communicating, short

circumferential branches of posterior cerebral (see Figure 5-27)

226

Synopsis of Functional Components, Tracts, Pathways, and Systems

Auditory Pathways

7-29

The origin, course, and distribution of the fibers collectively

hearing loss and conduction hearing loss, and to lateralize the deficit. In

composing the auditory pathway. Central to the cochlear nerve and

the Weber test, a tuning fork (512 Hz) is applied to the midline of the fore-

dorsal and ventral cochlear nuclei this system is, in a general sense, bi-

head or apex of the skull. In the normal patient, the sound (conducted

lateral and multisynaptic, as input is relayed through brainstem nuclei

through the bones of the skull) is heard the same in each year. In the case

en route to the auditory cortex. Synapse and crossing (or re-crossing)

of nerve deafness (lesions of the cochlea or cochlear nerve), the sound is best

of information can occur at several levels in the neuraxis. Conse-

heard in the normal ear, while in conductive deafness, the sound is best heard

quently, central lesions rarely result in a total unilateral hearing loss.

in the abnormal ear. In the Rinne test, a tuning fork (512 Hz) is placed

The medial geniculate body is the thalamic station for the relay of au-

against the mastoid process. When the sound is no longer perceived, the

ditory information to the temporal cortex.

prongs are moved close to the external acoustic meatus, where the sound

Neurotransmitters: Glutamate (

) and aspartate (

) are found in

is again heard; this is the situation in a normal individual (positive Rinne

some spiral ganglion cells and in their central terminations in the cochlear

test). In middle ear disease, the sound is not heard at the external meatus

nuclei. Dynorphin-containing and histamine-containing fibers are also

after it has disappeared from touching the mastoid bone (abnormal or neg-

present in the cochlear nuclei; the latter arises from the hypothalamus. A

ative Rinne test). Therefore, a negative Rinne test signifies conductive

noradrenergic projection to the cochlear nuclei and to the inferior col-

hearing loss in the ear tested. In mild nerve deafness (cochlea or cochlear

liculus originates from the nucleus locus ceruleus. Cells in the superior

nerve lesions), the sound is heard by application of the tuning fork to the

olive that contain cholecystokinin and cells in the nuclei of the lateral lem-

mastoid and movement to the ear (the Rinne test is positive). In severe

niscus that contain dynorphin project to the inferior colliculus. Although

nerve deafness, the sound may not be heard at either position.

the olivocochlear bundle is not shown, it is noteworthy that enkephalin is

In addition to hearing loss and tinnitus, large vestibular schwannomas

found in some of the cells that contribute to this projection.

may result in other signs and symptoms. These include nausea, vomiting

Clinical Correlations: There are three categories of deafness.

and ataxia/unsteady gait (vestibular root involvement), weakness of fa-

Conductive deafness is due to problems of the external ear (obstruction

cial muscles (facial root involvement), and altered sensation from the

of the canal, wax build-up) or disorders of the middle ear (otitis media,

face and a diminished corneal reflex (trigeminal root involvement).

otosclerosis). Nerve deafness (sensorineural hearing loss) results from diseases

There may also be general signs associated with increased intracranial

involving the cochlea or the cochlear portion of the vestibulocochlear

pressure (lethargy, headache, and vomiting).

nerve. Central deafness results from damage to the cochlear nuclei or

Central lesions (as in gliomas or vascular occlusions) rarely produce

possibly their central connections.

unilateral or bilateral hearing losses that can be detected, the possible

Hearing loss may result from trauma (such as fracture of the petrous

exception being pontine lesions that damage the trapezoid body and

bone), demyelinating diseases, tumors, certain medications (strepto-

nuclei. Injury to central auditory pathways and/or primary auditory

mycin), or occlusion of the labyrinthine artery. Damage to the cochlear

cortex may diminish auditory acuity, decrease the ability to hear cer-

part of the VIIIth nerve (as in vestibular schwannoma) results in tinnitus

tain tones, or make it difficult to precisely localize sounds in space. Pa-

and/or deafness (partial or total) in the ipsilateral ear. High-frequency

tients with damage to secondary auditory cortex in the temporal lobe

hearing losses are most common.

experience difficulty in understanding and/or interpreting sounds (au-

The Weber test and Rinne test are used to differentiate between neural

ditory agnosia).

Abbreviations

AbdNu Abducens nucleus

MLF Medial longitudinal fasciculus

ACNu Anterior (ventral) cochlear nucleus

PCNu Posterior (dorsal) cochlear nucleus

ALS Anterolateral system

PulNu Pulvinar nuclear complex

CC Crus cerebri

RB Restiform body

FacNu Facial nucleus

RetF Reticular formation

IC Inferior colliculus

SC Superior colliculus

IC,Br Inferior colliculus, brachium

SCP,Dec Superior cerebellar peduncle, decussation

IC,Com Inferior colliculus, commissure

SO Superior olive

IC,SL Internal capsule, sublenticular limb

SpGang Spiral ganglion

LGNu Lateral geniculate nucleus

SpTTr Spinal trigeminal tract

LL Lateral lemniscus

TrapB Trapezoid body

LL,Nu Lateral lemniscus, nucleus

TrapNu Trapezoid nucleus

MGNu Medial geniculate nucleus

TTGy Transverse temporal gyrus

ML Medial lemniscus

Review of Blood Supply to Cochlear Nuclei, LL (and associated

structures), Pontine Tegmentum, IC, and MGB

STRUCTURES

ARTERIES

Cochlear Nuclei

anterior inferior cerebellar (see Figure 5-14)

LL, SO in Pons

long circumferential branches of basilar (see Figure 5-21)

long circumferential branches (quadrigeminal branches) of basilar,

superior cerebellar (see Figure 5-27)

MGB

thalamogeniculate branches of posterior cerebral (see Figure 5-38)

228

Synopsis of Functional Components, Tracts, Pathways, and Systems

Vestibular Pathways

7-30

The origin, course, and distribution of the main afferent and

Clinical Correlations: The vestibular part of the VIIIth nerve can

efferent connections of the vestibular nuclei (see also Figures 7-13,

be damaged by many of the same insults that affect the cochlear nerve

7-19, and 7-20). Primary vestibular afferent fibers may end in the

(see Figure 7-29). Damage to vestibular receptors of the vestibular nerve

vestibular nuclei or pass to cerebellar structures via the juxtarestiform

commonly results in vertigo. The patient may feel that his or her body is

body. Secondary vestibulocerebellar axons originate from the vestibu-

moving (subjective vertigo) or that objects in the environment are moving

lar nuclei and follow a similar path to the cerebellum. Efferent projec-

(objective vertigo). They have equilibrium problems, an unsteady (ataxic)

tions from the vestibular nuclei also course to the spinal cord through

gait, and a tendency to fall to the lesioned side. Deficits seen in nerve le-

vestibulospinal tracts (see Figure 7-13), as well as to the motor nuclei

sions—or in brainstem lesions involving the vestibular nuclei, include

of the oculomotor, trochlear, and abducens nerves via the MLF. Cere-

nystagmus, nausea, and vomiting, along with vertigo and gait problems. A

bellar structures most extensively interconnected with the vestibular

facial palsy may also appear in concert with VIIIth nerve damage in pa-

nuclei include the lateral regions of the vermal cortex of anterior and

tients who have a vestibular schwannoma. These vestibular deficits, along

posterior lobes, the flocculonodular lobe, and the fastigial (medial)

with partial or complete deafness, are seen in Ménière disease.

cerebellar nucleus.

Lesions of those parts of the cerebellum with which the vestibular

Neurotransmitters: Gamma-aminobutyric (

) is the transmit-

nerve and nuclei are most intimately connected (flocculonodular lobe and

ter associated with many cerebellar corticovestibular fibers and their

fastigial nucleus) result in nystagmus, truncal ataxia, ataxic gait, and a

terminals in the vestibular complex; this substance is also seen in cere-

propensity to fall to the injured side. The nystagmus seen in patients with

bellar corticonuclear axons. The medial vestibular nucleus also has

vestibular lesions and the internuclear ophthalmoplegia seen in some patients

fibers that are dynorphin-positive and histamine-positive; the latter

with multiple sclerosis are signs that correlate with the interruption of

arise from cells in the hypothalamus.

vestibular projections to the motor nuclei of III, IV, and VI via the MLF.

Abbreviations

AbdNu Abducens nucleus

PAG Periaqueductal gray

ALS Anterolateral system

Py Pyramid

Cbl Cerebellar

RB Restiform body

Cbl-CoVes Cerebellar corticovestibular fibers

RNu Red nucleus

CblNu Cerebellar nuclei

SC Superior colliculus

HyNu Hypoglossal nucleus

SCP,Dec Superior cerebellar peduncle,

IC Inferior colliculus

decussation

InfVNu Inferior (spinal) vestibular nucleus

SN Substantia nigra

JRB Juxtarestiform body

SolNu Solitary nucleus

LVesSp Lateral vestibulospinal tract

SolTr Solitary tract

LVNu Lateral vestibular nucleus

SpTTr Spinal trigeminal tract

MesNu Mesencephalic nucleus

SVNu Superior vestibular nucleus

ML Medial lemniscus

TroNu Trochlear nucleus

MLF Medial longitudinal fasciculus

VesGang Vestibular ganglion

MVesSp Medial vestibulospinal tract

VesCbl,Prim Vestibulocerebellar fibers, primary

MVNu Medial vestibular nucleus

VesCbl,Sec Vestibulocerebellar fibers, secondary

OcNu Oculomotor nucleus

Review of Blood Supply to Vestibular Nuclei, TroNu, and OcNu

STRUCTURES

ARTERIES

Vestibular Nuclei

posterior inferior cerebellar in medulla (see Figure 5-14), long

circumferential branches of basilar in pons (see Figure 5-21)

TroNu and OcNu

paramedian branches of basilar bifurcation, medial branches of

posterior cerebral and posterior communicating, short

circumferential branches of posterior cerebral (see Figure 5-27)

232

Synopsis of Functional Components, Tracts, Pathways, and Systems

Hippocampal Connections

7-32

Selected afferent and efferent connections of the hippocam-

to the dentate gyrus, Ammon’s horn, and subiculum; and serotonin-

pus (upper) and the mammillary body (lower) with emphasis on the

ergic fibers arise from the rostral raphe nuclei.

circuit of Papez. The hippocampus receives input from, and projects

Clinical Correlations: Dysfunction associated with damage to

to, diencephalic nuclei (especially the mammillary body via the post-

the hippocampus is seen in patients with trauma to the temporal lobe,

commissural fornix), the septal region, and amygdala. The hippocam-

as a sequel to alcoholism, and as a result of neurodegenerative changes

pus receives cortical input from the superior and middle frontal gyri,

seen in the dementing diseases (such as Alzheimer disease and Pick disease).

superior temporal and cingulate gyri, precuneus, lateral occipital cor-

Bilateral injury to the hippocampus results in loss of recent memory

tex, occipitotemporal gyri, and subcallosal cortical areas. The mam-

(remote memory is unaffected), impaired ability to remember recent

millary body is connected with the dorsal and ventral tegmental nuclei,

(new) events, and difficulty in turning a new experience (something

anterior thalamic nucleus (via the mammillothalamic tract), septal nu-

just done or experienced) into a longer-term memory that can be re-

clei, and through the mammillotegmental tract, to the tegmental pon-

trieved at a later time. Also, memory that depends on visual, tactile,

tine and reticulotegmental nuclei.

or auditory discrimination is noticeably affected. These represent visual

Neurotransmitters: Glutamate

(

)-containing cells in the

agnosia, tactile agnosia, and auditory agnosia, respectively.

subiculum and Ammon’s horn project to the mammillary body, other

In the Korsakoff syndrome (amnestic confabulatory syndrome) there is mem-

hypothalamic centers, and the lateral septal nucleus through the fornix.

ory loss, dementia, amnesia, and a tendency to give confabulated re-

Cholecystokinin (

) and somatostatin (

) are also found in hip-

sponses. This type of response is fluent but consists of a string of unrelated,

pocampal cells that project to septal nuclei and hypothalamic struc-

or even made up, “memories” that never actually occurred or make no

tures. The septal nuclei and the nucleus of the diagonal band give rise

sense. This may lead to an incorrect conclusion that the patient is suffer-

to cholinergic afferents to the hippocampus that travel in the fornix. In

ing from dementia. In addition to lesions in the hippocampus in these pa-

addition, a gamma-aminobutyric acid (

) septohippocampal projec-

tients, the mammillary bodies and dorsomedial nucleus of the thalamus

tion originates from the medial septal nucleus. Enkephalin and gluta-

are noticeably affected. The Korsakoff syndrome (see also the Wernicke-

mate containing hippocampal afferent fibers arise from the adjacent en-

Korsakoff syndrome) as seen in chronic alcoholics is largely owing to thi-

torhinal cortex; the locus ceruleus gives origin to noradrenergic fibers

amine deficiency and can be treated with therapeutic doses of this vitamin.

Abbreviations

AC Anterior commissure

LT Lamina terminalis

AmHrn Ammon’s horn

MB Mammillary body

Amy Amygdaloid nucleus (complex)

MedFCtx Medial frontal cortex

AntNu Anterior nucleus of thalamus

MedTh Medial thalamus

CC, G Corpus callosum, genu

MTegTr Mammillotegmental tract

CC,Spl Corpus callosum, splenium

MtTr Mammillothalamic tract

Cing Cingulum

NuAcc Nucleus accumbens

CingGy Cingulate gyrus

OpCh Optic chiasm

CorHip Corticohippocampal fibers

Pi Pineal

DenGy Dentate gyrus

RSplCtx Retrosplenial cortex

EnCtx Entorhinal cortex

SepNu Septal nuclei

For Fornix

SMNu Supramammillary nucleus

GyRec Gyrus rectus

Sub Subiculum

Hip Hippocampus

TegNu Tegmental nuclei

Hyth Hypothalamus

VmNu Ventromedial hypothalamic nucleus

IC,G Internal capsule, genu

Review of Blood Supply to Hip, MB, Hyth, and CingGy

STRUCTURES

ARTERIES

Hip

anterior choroidal (see Figure 5-38)

MB, Hyth

branches of circle of Willis (see Figure 2-21)

AntNu

thalamoperforating (see Figure 5-38)

CingGy

branches of anterior cerebral

234

Synopsis of Functional Components, Tracts, Pathways, and Systems

Amygdaloid Connections

7-33

The origin, course, and distribution of selected afferent and

complex. Acetylcholine is present in afferents to the amygdala from the

efferent connections of the amygdaloid nuclear complex in sagittal (up-

substantia innominata, as well as from the septal area. In patients with

per) and coronal (lower) planes. The amygdala receives input from,

Alzheimer disease and the associated dementia, there is a marked loss

and projects to, brainstem and forebrain centers via the stria terminalis

of acetylcholine-containing neurons in the basal nucleus of the sub-

and the ventral amygdalofugal pathway. Corticoamygdaloid and amyg-

stantia innominata, in the cortex, and in the hippocampus.

dalocortical fibers interconnect the basal and lateral amygdaloid nuclei

Clinical Correlations: Dysfunctions related to damage to the

with select cortical areas.

amygdaloid complex are seen in patients with trauma to the temporal

Neurotransmitters: Cells in the amygdaloid complex contain

lobes, herpes simplex encephalitis, bilateral temporal lobe surgery to treat

vasoactive intestinal polypeptide (VIP,

), neurotensin (NT), so-

intractable epileptic activity, and in some CNS degenerative disorders

matostatin (SOM,

), enkephalin (ENK,

), and substance P (SP,

(such as Alzheimer disease and Pick disease). The behavioral changes seen

These neurons project, via the stria terminalis or the ventral amyg-

in individuals with amygdala lesions collectively form the Klüver-Bucy

dalofugal path, to the septal nuclei (VIP, NT), the bed nucleus of the

syndrome. In humans these changes/deficits are 1) hyperorality; 2) visual,

stria terminalis (NT, ENK, SP), the hypothalamus (VIP, SOM, SP), the

tactile, and auditory agnosia; 3) placidity; 4) hyperphagia or other dietary

nucleus accumbens septi, and the caudate and putamen (NT). Sero-

manifestations; 5) an intense desire to explore the immediate environ-

tonergic amygdaloid fibers originate from the nucleus raphe dorsalis

ment (hypermetamorphosis), and 6) what is commonly called hypersexual-

and the superior central nucleus, dopaminergic axons from the ventral

ity. These changes in sexual attitudes are usually in the form of com-

tegmental area and the substantia nigra-pars compacta, and noradren-

ments, suggestions, and attempts to make a sexual contact (such as

alin-containing fibers from the locus ceruleus. Glutamate (

) is found

touching) rather than in actual intercourse or masturbation. These pa-

in olfactory projections to the prepiriform cortex and the amygdaloid

tients may also show aphasia, dementia, and amnesia.

Abbreviations

AC Anterior commissure

NuRa,d Nucleus raphe, dorsalis

Amy Amygdaloid nuclear complex

NuRa,m Nucleus raphe, magnus

AmyCor Amygdalocortical fibers

NuRa,o Nucleus raphe, obscurus

AmyFugPath Amygdalofugal pathway

NuRa,p Nucleus raphe, pallidus

AntHyth Anterior hypothalamus

NuStTer Nucleus of the stria terminalis

Ba-LatNu Basal and lateral nuclei

OlfB Olfactory bulb

CaNu Caudate nucleus

OpCh Optic chiasm

Cen-MedNu Central, cortical and medial nuclei

PAG Periaqueductal (central) gray

CorAmy Corticoamygdaloid fibers

PBrNu Parabrachial nuclei

DVagNu Dorsal motor vagal nucleus

PfNu Parafascicular nucleus

EnCtx Entorhinal cortex

Pi Pineal

For Fornix

POpNu Preoptic nucleus

GP Globus pallidus

PPriCtx Prepiriform cortex

Hyth Hypothalamus

Put Putamen

LT Lamina terminalis

SepNu Septal nuclei

LHAr Lateral hypothalamic area

SNpc Substantia nigra, pars compacta

MedThNu Medial thalamic nuclei

SolNu Solitary nucleus

MGNu Medial geniculate nucleus

StTer Stria terminalis

MidTh Midline thalamic nuclei

Sub Subiculum

NuAcc Nucleus accumbens

Subln Substantia innominata

NuCen,s Nucleus centralis, superior

VenTegAr Ventral tegmental area

NuCer Nucleus ceruleus

VmNu Ventromedial hypothalamic nucleus

Review of Blood Supply to Amy and Related Centers

STRUCTURES

ARTERIES

Amy

anterior choroidal (see Figure 5-38)

Hyth

branches of circle of Willis (see Figure 5-38)

Brainstem

(see Figures 5-14, 5-21, and 5-27)

Thalamus

thalamoperforating, thalamogeniculate (see Figure 5-38)

242

Anatomical-Clinical Correlations

Middle cerebral artery

(M4-cortical branches)

Anterior cerebral artery

(A4, A5)

Middle cerebral artery

(M2-insular branches)

Anterior cerebral artery

(A3)

Lenticulostriate branches

(A2)

(of M1)

(A1)

Middle cerebral artery

(M1)

Internal carotid artery

(cavernous part)

Internal carotid artery

(cerebral part)

Internal carotid artery

(petrous part)

8-3

Internal carotid angiogram (anterior-posterior projection,

(supracallosal) and A5 (postcallosal) segments are located superior

arterial phase). Note general distribution patterns of anterior and

(above) the corpus callosum.

middle cerebral arteries and the location of lenticulostriate

The M₁ segment of the middle cerebral artery is located between

branches. The A₁ segment of the anterior cerebral artery is located

the internal carotid bifurcation and the point at which this vessel

between the internal carotid bifurcation and the anterior communi-

branches into superior and inferior trunks on the insular cortex. As

cating artery. The distal portion of the anterior cerebral artery

branches of the middle cerebral artery pass over the insular cortex they

(ACA) immediately rostral to the anterior communicating artery

are designated as M₂, as M₃ when these branches are located on the in-

and inferior to the rostrum of the corpus callosum is the A2 segment

ner surface of the frontal, parietal, and temporal opercula, and as M₄

(infracallosal). The portion of the ACA arching around the genu of

where they exit the lateral sulcus and fan out over the lateral aspect of

the corpus callosum is the A3 segment (precallosal) and the A4

the cerebral hemisphere. Compare with Figure 2-21 on page 25.

Blood Supply to the Choroid Plexi

251

Choroid plexus (CP) in

body of lateral ventricle

CP in atrium of lateral ventricle

CP in roof of third ventricle

CP in temporal horn

of lateral ventricle

Anterior choroidal artery

CP in fourth ventricle

AICA

PICA

Posterior communicating artery

Lateral posterior choroidal artery

Medial posterior choroidal artery

Medial striate artery

Internal carotid artery

Middle cerebral artery (M₁)

P₁

Anterior choroidal artery

Posterior communicating artery

Posterior cerebral artery (P₂)

Lateral posterior choroidal artery

Superior cerebellar artery

Medial posterior choroidal artery

Basilar artery (BA)

Anterior inferior cerebellar artery (AICA)

AICA branch to choroid plexus

at the foramen of Luschka

Vertebral artery (VA)

Posterior inferior cerebellar artery (PICA)

PICA branch to choroid plexus

in the fourth ventricle

8-12

Blood supply to the choroid plexus of the lateral, third, and

rior lateral choroidal arteries serve the plexuses of the lateral and third

fourth ventricles. Those branches of the vertebrobasilar system and of the

ventricles. The choroid plexus in the fourth ventricle and the clump of

internal carotid artery and P2 segment of the posterior cerebral artery that

choroid plexus protruding out of the foramen of Luschka are served by

supply the choroid plexus are accentuated by appearing in a darker red

posterior inferior and anterior inferior cerebellar arteries, respectively. In

shade. In A, a representation of these vessels (origin, course, termination)

B, the origins of these branches from their main arterial trunks are shown.

is shown from the lateral aspect. Anterior, posterior medial, and poste-

See also Figures 2-21 (page 25), 2-24 (page 27), and 2-35 (page 35).

252

Anatomical-Clinical Correlations

Anterior cerebral artery

Middle cerebral artery

A₂

M₂

A₁

M₁

Internal carotid artery

Cerebral part

Cavernous part

Basilar artery

Petrosal part

Anterior inferior

cerebellar artery

Cervical part

Vertebral artery

Posterior inferior

cerebellar artery

Maxillary artery

(br. of external

carotid artery)

Internal carotid artery

Vertebral artery

External carotid artery

Common carotid artery

Posterior cerebral artery

Superior cerebellar artery

Position of

occulomotor nerve

Basilar artery

Anterior inferior

cerebellar artery

Vertebral artery

(intercranial portion)

Vertebral artery

Anterior inferior

(passing caudally and

cerebellar artery

medially around the lateral

mass of the atlas)

Vertebral artery

(passing through transverse

foramen of the atlas)

8-13

Overview (A) of the arteries in the neck that serve the brain (in-

The vertebral artery (VA) is generally described as being composed

ternal carotid and vertebral) and of their main terminal branches (anterior

of 4 segments sometimes designated as V₁ to V₄. The first segment (V₁)

cerebral artery and middle cerebral artery, vertebrobasilar system) as seen

is between the VA origin from the subclavian artery and the entrance

in an MRA (anterior-posterior view). In approximately 40-45% of indi-

of VA into the first transverse foramen (usually C6); the second seg-

viduals the left vertebral artery is larger, as seen here, and in about 5-10%

ment V₂ is that part of VA ascending through the transverse foramen

of individuals one or the other of the vertebral arteries may be hypoplas-

of C6 to C2; the third segment (V₃) is between the exit of VA from the

tic as seen here on the patient’s right. The MRI in B is a detailed view of

transverse foramen of the axis and the dura at the foramen magnum

the vertebrobasilar system from the point where the vertebral arteries exit

(this includes the loop of the VA that passes through the transverse

the transverse foramen to where the basilar artery bifurcates into the pos-

foramen of C1/the atlas); the fourth segment (V₄) pierces the dura and

terior cerebral arteries. Compare this image with Figure 2-21 on page 25.

joins its counterpart to form the basilar artery.

CHAPTER

Q & A’s: A Sampling of Study and Review

Questions, Many in the USMLE Style,

All With Explained Answers

D. E. Haines and J. A. Lancon

There are two essential goals of a student studying human neu-

cise, some answers may contain additional relevant informa-

robiology, or, for that matter, the student of any of the medical

tion to extend the educational process.

sciences. The first is to gain the knowledge base and diagnostic

In general, the questions are organized by individual chapters,

skills to become a competent health care professional. Address-

although chapters 1 and 2 and chapters 3 and 4 are combined. Ref-

ing the medical needs of the patient with insight, skill, and com-

erence to the page (or pages) containing the correct answer are

passion is paramount. The second is to successfully negotiate

usually to the chapter(s) from which the question originated.

whatever examination procedures are used in a given setting.

However, recognizing that neuroscience is dynamic and three-di-

These may be standard class examinations, Subject National

mensional, some answers contain references to chapters other

Board Examination (now used/required in many courses), the

than that from which the question originated. This provides a

USMLE Step 1 Examination (required of all U.S. medical stu-

greater level of integration by bringing a wider range of informa-

dents), or simply the desire, on the part of the student, for self-

tion to bear on a single question.

assessment.

Correct diagnosis of the neurologically compromised patient

The questions in this chapter are prepared in two general

not only requires integration of information contained in differ-

styles. First, there are study or review questions that test gen-

ent chapters but may also require inclusion of concepts gained in

eral knowledge concerning the structure of the central ner-

other basic science courses. In this regard a few questions, and

vous system. Many of these have a functional flavor. Second,

their answers, may include such additional basic concepts.

there are single one best answer questions in the USMLE style

This is not an all-inclusive list of questions, but rather a

that use a patient vignette approach in the stem. These ques-

sampling that covers a wide variety of neuroanatomical and

tions have been carefully reviewed for clinical accuracy and

clinically relevant points. There is certainly a much larger va-

relevance as used in these examples. At the end of each ex-

riety of questions that could be developed from the topics cov-

plained answer, page numbers appear in parentheses that

ered in this atlas. It is hoped that this sample will give the user

specify where the correct answer, be it in a figure or in the text,

a good idea of how basic neuroscience information correlates

may be found. In order to make this a fruitful learning exer-

with a range of clinically relevant topics.

254

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

In addition to the vestibulocochlear nerve, which of the following

Review and Study Questions for

structures would most likely also be affected by the tumor in this

Chapters 1 and 2

man?

(A) Anterior inferior cerebellar artery

A 71-year-old man complains to his family physician that his face

(B) Facial nerve

“feels funny.” The examination reveals numbness on his face and

on the same side of his tongue. MRI shows a lesion in the cerebral

(D) Posterior inferior cerebellar artery

cortex. This man’s lesion is most likely located in which of the fol-

(E) Vagus nerve

lowing cortical regions?

(A) Anterior paracentral

A 67-year-old man complains to his family physician of severe

(B) Lateral one-third of the postcentral

headaches. The examination reveals visual deficits in both eyes,

and MRI shows a lesion in the cerebral cortex. Which of the fol-

(D) Middle one-third of the postcentral

lowing cortical structures represents the most likely location of

(E) Posterior paracentral

this lesion?

(A) Angular gyrus

A 41-year-old woman complains to her family physician about re-

(B) Cingulate gyrus

curring episodes of sharp pain that seem to originate from around

her mouth and cheek. The pain is so intense that she is unable to

(D) Parahippocampal gyrus

eat, brush her teeth, or apply make-up. Which of the following

(E) Precuneus

cranial nerves is the most likely source of this pain?

(A) Facial (VII)

A sagittal MRI of a 23-year-old woman is located at, or immedi-

(B) Glossopharyngeal (IX)

ately adjacent to, the midline. Which of the following spaces or

structures would be in the image and would indicate a midline

(D) Trigeminal (V)

plane?

(E) Vagus (X)

(A) Cerebral aqueduct

(B) Corpus callosum

The labyrinthine artery is an important source of blood supply to

the inner ear. Which of the following arteries represents the ma-

(D) Interventricular foramen

jor vessel from which this branch usually arises?

(E) Superior colliculus

(A) Anterior inferior cerebellar

(B) Basilar

A 20-year-old man is brought to the emergency department from

the site of a motorcycle accident. He is unconscious and has a bro-

(D) Superior cerebellar

ken femur, humerus, and extensive facial injuries. Axial CT shows

(E) Vertebral

a white layer on the lateral aspect of the left hemisphere that is ap-

proximately 5 mm thick and extends for 12 cm. This observation

The quadrigeminal artery in a 20-year-old man is occluded by a fat

most likely represents:

embolus originating from a compound fracture of the humerus.

(A) Epidural hemorrhage/hematoma

Which of the following structures does this occluded vessel most

(B) Parenchymatous hemorrhage in the cortex

directly affect?

(A) Superior cerebellar peduncle

(D) Subdural hemorrhage/hematoma

(B) Mammillary bodies

(E) Ventricular hemorrhage

(D) Pineal and habenula

10.

Which of the following portions of the ventricular system does not

(E) Superior and inferior colliculi

contain choroid plexus?

(A) Cerebral aqueduct

Questions 5 and 6 are based on the following patient.

(B) Fourth ventricle

A 63-year-old man has hearing loss, tinnitus (ringing or buzzing sounds

in the ear), vertigo, and unsteady gait; all of these have developed over

(D) Interventricular foramen

several years. MRI reveals a large tumor (3 cm in diameter) at the cere-

(E) Third ventricle

bellopontine angle, most likely a vestibular schwannoma (sometimes

incorrectly called an acoustic neuroma).

11.

A 47-year-old man presents with an intense pain on his face aris-

ing from stimulation at the corner of his mouth. This is character-

5. What additional deficit could this patient also have?

istic of trigeminal neuralgia (tic douloureux). MRI shows a vessel

compressing the root of the trigeminal nerve. Which of the fol-

(A) Anosmia

lowing vessels would most likely be involved?

(B) Hemianopsia

(A) Anterior inferior cerebellar artery

(D) Visual field deficits

(B) Basal vein (of Rosenthal)

(E) Weakness of the tongue

(D) Posterior cerebral artery

(E) Superior cerebellar artery

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

255

12.

Which of the following cranial nerves contain the afferent and ef-

18.

A lumbar puncture, commonly called a “lumbar tap,” consists of a

ferent limbs of the corneal reflex?

needle being inserted through an intervertebral space into the

lumbar cistern to retrieve a sample of cerebrospinal fluid. Which

(A) II and III (optic and oculomotor)

of the following is the most likely level for the insertion of the nee-

(B) III, IV, VI (oculomotor, trochlear, abducens)

dle?

(D) VIII and IX (vestibulocochlear, glossopharyngeal)

(A) L1-L2

(E) IX and X (glossopharyngeal, vagus)

(B) L2-L3

13.

A 73-year-old man is brought to the emergency department after

(D) S1-S2

being found in his garage in a state of confusion. CT shows an in-

(E) T12-L1

farct involving much of the superior frontal gyrus. Which of the

following vessels is most likely occluded in this patient?

19.

A 59-year-old man complains of persistent headache. An MRA

(Magnetic Resonance Angiography) shows an aneurysm in the in-

(A) Angular artery

terpeduncular fossa (and cistern) arising from the basilar tip.

(B) Callosomarginal artery

Which of the following cranial nerves would be most directly af-

fected by this aneurysm?

(D) Middle cerebral artery, M₄ segments

(E) Posterior cerebral artery, P₄ segments

(A) Abducens (VI)

(B) Oculomotor (III)

14.

The MRI of a 49-year-old woman shows a tumor located immedi-

ately superior to the corpus callosum. This lesion is most likely lo-

(D) Trigeminal, V1 (V)

cated in which of the following lobes?

(E) Trochlear (IV)

(A) Frontal

20.

A 71-year-old man presents with a Broca (nonfluent) aphasia. MRI

(B) Limbic

reveals a lesion in Brodmann area 44. As this lesion expands, due

to edema, and impinges on the immediately adjacent cortical ar-

(D) Parietal

eas, which of the following deficits would most likely be seen?

(E) Temporal

(A) Loss of hearing in one ear

15.

A 69-year-old woman is brought to the emergency department.

(B) Numbness and prickly sensation on the hand

The daughter reports that her mother suddenly seemed to be un-

able to speak. The examination reveals that the woman has a non-

(D) Weakness of facial muscles

fluent (Broca) aphasia. A sagittal MRI shows a lesion in which of

(E) Weakness of the upper extremity

the following gyri?

21.

A 47-year-old woman presents with seizures and ill-defined neu-

(A) Angular

rologic complaints. The examination reveals a bruit on the lateral

(B) Inferior frontal

aspect of the head immediately rostral and superior to the ear. A

CT shows a large arteriovenous malformation in the area of the lat-

(D) Middle frontal

eral sulcus. The feeding artery(ies) is M₄ branches. Which of the

(E) Supramarginal

following most likely represents the major draining vein?

16.

Which of the following Brodmann areas represents the primary

(A) Inferior sagittal sinus

somatosensory cortex?

(B) Internal cerebral vein

(A) Areas 3, 1, 2

(D) Superficial middle cerebral vein

(B) Area 4

(E) Superior petrosal sinus

(D) Area 22

22.

The collection of posterior and anterior roots that occupy the lum-

(E) Area 40

bar cistern are collectively known as which of the following?

17.

A 64-year-old man awakens with a profound weakness of his right

(A) Cauda equina

hand. The man is transported by ambulance to a major medical

(B) Conus medullaris

center, a distance of 240 miles and taking several hours. About 2.5

hours after his arrival, an MRI shows a small lesion in the cerebral

(D) Filum terminale externum

cortex. Which of the following gyri represents the most likely lo-

(E) Filum terminale internum

cation of this lesion?

23.

Which of the following Brodmann areas represents the primary

(A) Anterior paracentral

somatomotor cortex?

(B) Medial one-third of precentral

(A) Areas 3,1,2

(D) Middle one-third of precentral

(B) Area 4

(E) Lateral one-third of precentral

(D) Area 6

(E) Area 7

256

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

24.

A 39-year-old woman complains of weakness in her right lower

30.

The abducens nerve exits the brainstem at the pons-medulla junc-

extremity. The history suggests that this deficit has developed

tion generally in line with the preolivary sulcus and passes rostrally

slowly, perhaps over several years. MRI shows a meningioma im-

just lateral to, and in the same cistern as, the basilar artery. Which

posing on the cerebral cortex. Which of the following gyri is most

of the following cisterns contains the abducens nerve and basilar

likely involved in this patient?

artery?

(A) Anterior paracentral

(A) Ambient

(B) Lateral part of precentral

(B) Inferior cerebellopontine

(D) Medial part of postcentral

(D) Prepontine

(E) Posterior paracentral

(E) Superior cerebellopontine

25.

A 71-year-old woman presents with motor and sensory deficits af-

31.

An 81-year-old woman is brought to the emergency department

fecting her face and upper extremity. CT shows a hemorrhage that

by her son with a complaint of weakness on the same side of her

is confined largely to the cortex and adjacent subcortical areas.

body and face. CT shows a hemorrhage in the territory of the

Which of the following vessels/segments are most likely involved?

lenticulostriate arteries. Which of the following represents the

(A) A₁

most likely origin of these vessels?

(B) M₂

(A) A₁

(B) M₁

(D) M₄

(E) P₄

(D) P₁

(E) P₂

26.

A 22-year-old man is brought to the emergency department with

a gunshot wound to the head. He is decorticate but soon becomes

32.

The MRI of a 27-year-old woman shows a meningioma impinging

decerebrate. This change in status is due to uncal herniation.

on the gyrus rectus in axial and coronal MRI. This lesion is located

Which of the following most specifically describes the position of

on which of the following lobes of the cerebral hemisphere?

the uncus prior to herniation?

(A) Frontal

(A) At the temporal lobe

(B) Insular

(B) Caudal aspect of the cingulate gyrus

(D) Parietal

(D) Medial edge of occipitotemporal gyri

(E) Temporal

(E) Rostromedial aspect of the parahippocampal gyrus

33.

A 51-year-old man presents with visual field deficits in both eyes

27.

A 73-year-old woman presents with visual deficits in both eyes.

and a right-sided weakness of the upper and lower extremities.

No other cranial nerve deficits or motor or sensory deficits are

MRI shows a lesion in the optic tract that has spread into a struc-

seen. CT shows a hemorrhage in the cerebral cortex. Which of the

ture located immediately adjacent to this tract. Based on its

following vessels/segments is most likely involved in this hemor-

anatomical relationship, which of the following structures is most

rhage?

likely involved in a lesion spreading from the optic tract?

(A) A₁

(A) Left basilar pons

(B) M₃

(B) Left crus cerebri

(D) P₂

(D) Right crus cerebri

(E) P₄

(E) Right optic nerve

28.

The CT of a 77-year-old man shows a calcified tuft of choroid

34. A 19-year-old man presents with significant paralysis of move-

plexus, the glomus choroideum. Which of the following repre-

ment in his left eye and a dilated pupil. No other deficits are

sents the location of this part of the choroid plexus?

seen. Suspecting some type of lesion on the root or along the

(A) Anterior horn of the lateral ventricle

intracranial course of the oculomotor (III) nerve, the neurolo-

(B) Atrium of the lateral ventricle

gist orders an MRI. Which of the following describes the ap-

pearance of the subarachnoid and ventricular spaces in a T2-

(D) Caudal roof of the third ventricle

weighted image?

(E) Temporal horn of the lateral ventricle

(A) Black (hypointense)

(B) Dark grey

29.

Which of the following represents the most common cause of

blood in the subarachnoid space (subarachnoid hemorrhage)?

(D) Medium grey

(A) Bleeding from an arteriovenous malformation

(E) White (hyperintense)

(B) Bleeding from a meningioma

(D) Rupture of an aneurysm

(E) Trauma to the brain

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

257

35.

A 49-year-old woman presents with ill-defined neurologic deficits

41.

The MRI of an 11-year-old boy shows a tumor in the pontine por-

that have persisted over several months. As part of the evaluation,

tion of the fourth ventricle. The rostral edge of which of the fol-

the neurologist orders an MRI. Which of the following describes

lowing structures represents the border between the medullary

the appearance of CSF in the ventricular spaces, and consequently

and pontine parts of the fourth ventricle?

the outline and shape of the ventricles, in a T1-weighted image?

(A) Facial colliculus

(A) Black (hypointense)

(B) Hypoglossal trigone

(B) Dark grey

(D) Stria medullares

(D) Medium grey

(E) Vagal trigone

(E) White (hyperintense)

42.

A 61-year-old man presents with a tremor and unsteady gait; these

36.

A 71-year-old morbidly obese man is brought to the emergency

problems are on the same side of his body. Sagittal MRI shows a

department by his son. The son reports that the man complained

lesion in the anterior lobe of the cerebellum. Which of the fol-

of a sudden excruciating headache and then became stuporous.

lowing represents the fissure separating the anterior and posterior

Suspecting a ruptured aneurysm the physician orders a CT. Which

lobes of the cerebellum?

of the following describes the appearance of acute blood in the

(A) Horizontal fissure

subarachnoid space in CT?

(B) Posterior superior fissure

(A) Black (hypodense)

(B) Black to grey

(D) Primary fissure

(E) Secondary fissure

(D) Medium grey

(E) White (hyperdense)

43.

The MRI of a 49-year-old woman with a brain tumor shows ton-

sillar herniation. Based on its anatomical position, which of the fol-

37.

Which of the following cranial nerves exits the brainstem via the

lowing portions of the brainstem would be most adversely affected

preolivary sulcus?

by tonsillar herniation?

(A) Abducens (VI)

(A) Caudal midbrain

(B) Facial (VII)

(B) Caudal pons

(D) Vagus (X)

(D) Rostral midbrain

(E) Trigeminal (V)

(E) Rostral pons

38.

A 29-year-old woman becomes acutely ill with high fever, a stiff

44.

A 4-year-old boy is brought to the emergency department by his

neck, and stupor. A lumbar puncture reveals cloudy cerebrospinal

mother who explains that the boy fell off a porch onto a concrete

fluid from which organisms are cultured. Which of the following

sidewalk. The examination reveals that the boy has a parietal scalp

represents the most frequently seen organisms in cases of adult

laceration, is stuporous, and has reactive pupils. Suspecting that

bacterial meningitis?

this boy may have a possible skull fracture with some type of in-

tracranial bleeding, which of the following imaging tests would be

(A) Escherichia coli

most immediately (and appropriately) useful?

(B) Haemophilus influenzae

(A) CT

(D) Listeria monocytogenes

(B) MRI, gadolinium enhanced

(E) Streptococcus pneumoniae

(D) MRI, T2-weighted

39.

Which of the following cranial nerves exits the posterior (dorsal)

(E) PET (Positron Emission Tomography)

aspect of the brainstem?

45.

A sagittal MRI of a 52-year-old man clearly shows a small tumor

(A) Abducens (VI)

in the area of the long and short gyri. These gyri are characteristi-

(B) Hypoglossal (XII)

cally found in which of the following lobes?

(D) Trochlear (IV)

(A) Frontal

(E) Vestibulocochlear (VIII)

(B) Insular

40.

Which of the following cranial nerves passes between the poste-

(D) Occipital

rior cerebral artery and the superior cerebellar artery as it exits the

(E) Parietal

brainstem?

46.

A lesion involving the root of which of the following nerves would

(A) Abducens

most likely have an effect on the gag reflex?

(B) Oculomotor

(A) Accessory

(D) Trigeminal

(B) Facial

(E) Vestibulocochlear

(D) Hypoglossal

(E) Trigeminal

258

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

Answer A: The cerebral aqueduct is about 1.5-2.0 mm in di-

Answers for Chapters 1 and 2

ameter, and connects the third ventricle with the fourth ventricle.

When this part of the ventricular system appears in a sagittal MRI,

Answer B: Numbness on the face, resulting from a lesion in the

the plane of the scan is at the midline. Neither the interventricu-

cerebral cortex, indicates a lesion in the lateral one-third of the

lar foramen nor the superior colliculus are on the midline. Both

postcentral gyrus (face area of the somatosensory cortex). The an-

the interpeduncular fossa and the corpus callosum are on the mid-

terior paracentral gyrus and the precentral gyrus are somatomotor

line, but extend off the midline well beyond the width of the cere-

areas of the cerebral cortex. The upper extremity is represented in

bral aqueduct. (p. 28-31, 49, 50, 52)

the middle one-third of the postcentral gyrus and the lower ex-

tremity is represented in the posterior paracentral gyrus. (p. 15)

Answer D: Trauma may cause epidural hemorrhage, subdural

hemorrhage, or subarachnoid hemorrhage. Acute subdural hem-

Answer D: Tic douloureux (trigeminal neuralgia) is a lancinat-

orrhage/hematoma will appear white in CT and will usually pre-

ing pain that originates from the territories of the trigeminal

sent as a comparatively thin but long defect. Epidural hemorrhage

nerve, primarily its V2 or V3 territories. The trigger zone is fre-

will usually be seen as a shorter but thicker lesion and may appear

quently around the corner of the mouth. There is a geniculate neu-

loculated (have some sort of internal structure). The structure

ralgia (related to the ear) and a glossopharyngeal neuralgia (related

(shape) of this lesion does not conform to hemorrhage into the

to the throat or palate), but neither of these originates from the

substance of the brain (brain parenchyma), into the subarachnoid

surface of the face near the oral cavity. The hypoglossal nerve is

space (or cisterns), and certainly not to hemorrhage into the ven-

the motor for the tongue and the vagus is the motor for most of

tricles. (p. 46, 48, 51)

the pharynx and larynx, visceromotor for much of the gut, and

contains viscerosensory fibers from the gut. (p. 41)

10.

Answer A: The only portion of the ventricular system that does

not contain choroid plexus is the cerebral aqueduct. The choroid

Answer A: In most cases (85-100%), the labyrinthine artery,

plexus in the lateral ventricle is continuous from the inferior horn

also called the internal auditory artery, originates from the ante-

into the atrium and into the body of the ventricle, and through the

rior inferior cerebellar artery. It enters the internal acoustic mea-

interventricular foramen with the choroid plexus located along

tus, serves bone and dura of the canal, the nerves of the canal, and

the roof of the third ventricle. There is a tuft of choroid plexus in

vestibular and cochlear structures. In a few cases (15% or less),

the fourth ventricle, a small part of which extends into the lateral

this artery originates from the basilar artery. None of the other

recess and through the lateral foramen (of Luschka) into the sub-

choices gives rise to vessels that serve the inner ear. (p. 25, 27)

arachnoid space at the cerebellopontine angle. (p. 52-53)

Answer E: The quadrigeminal artery is the primary blood sup-

11.

Answer E: Branches of the superior cerebellar artery are most

ply to the superior and inferior colliculi: this vessel originates from

frequently involved in cases of trigeminal neuralgia that are pre-

P₁. The geniculate bodies receive their blood supply from the thal-

sumably of vascular origin. The posterior cerebral artery and its

amogeniculate arteries, and the pineal and habenula from the pos-

larger branches serve the midbrain-diencephalic junction or join

terior medial choroidal artery. The superior cerebellar peduncle

the medial surface of the hemisphere. The basilar artery serves the

receives its blood supply via the medial branch of the superior

basilar pons and the anterior inferior cerebellar artery serves the

cerebellar artery, and branches of the cerebral circle (of Willis)

caudal midbrain, inner ear, and the inferior surface of the cere-

serve the mammillary bodies. (p. 25, 35)

bellar surface. The basal vein drains the medial portions of the

hemisphere and passes through the ambient cistern to enter the

Answer C: Vestibular schwannomas larger than 2.0 cm in diame-

great cerebral vein (of Galen). (p. 41)

ter may impinge on the root of the trigeminal nerve and cause numb-

ness on the same side of the face. Although the other deficits listed

12.

Answer C: The afferent limb of the corneal reflex is via the oph-

are not seen in these patients, diplopia (involvement of oculomotor,

thalmic division of the trigeminal nerve (V); the cell body of ori-

abducens or trochlear nerves, singularly or in combination) may be

gin is in the trigeminal ganglion and the central terminations in the

present, but in fewer than 10% of these individuals. (p. 42)

pars caudalis of the spinal trigeminal nucleus. The efferent limb

originates in the motor nucleus of the facial nerve (VII) and dis-

Answer B: The internal acoustic meatus contains the vestibulo-

tributes to the facial muscles around the eye. None of the other

cochlear nerve, the facial nerve, and the labyrinthine artery, a

choices contains fibers related to the corneal reflex. (p. 42)

branch of the anterior inferior cerebellar artery. A vestibular

schwannoma located in the meatus would likely affect the facial

13.

Answer B: The callosomarginal artery, a branch of the anterior

nerve and result in facial weakness. The vagus and glossopharyn-

cerebral artery, serves the medial aspect of the superior frontal

geal nerves exit the skull via the jugular foramen (along with the

gyrus and that portion of this gyrus on the superior and lateral as-

accessory nerve). The cerebellar arteries originate within the skull

pects of the hemisphere. M₄ segments of the middle cerebral

and distribute to structures within the skull. (p. 42)

artery serve the lateral aspects of the hemisphere; P₄ segments of

the posterior cerebral artery serve the medial aspects of the hemi-

Answer C: The lingual gyrus is the lower bank of the calcarine sul-

sphere caudal to the parietoccipital sulcus, and the angular artery

cus; the upper (cuneus) and lower banks of this sulcus are the loca-

(an M₄ branch) serves the angular gyrus of the inferior parietal lob-

tion of the primary visual cortex. The precuneus is the medial aspect

ule. The lenticulostriate arteries are branches of M₁ that serve in-

of the parietal lobe, and the angular gyrus is a portion of the inferior

ternal structures of the hemisphere. (p. 17, 29)

parietal lobule on the lateral aspect of the hemisphere. The cingu-

late and parahippocampal gyri are located on the medial aspect of the

14.

Answer B: The limbic lobe, consisting primarily of the cingu-

hemisphere and are parts of the limbic lobe. (p. 13-15, 28)

late gyrus and the parahippocampal gyrus, is located on the most

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

259

medial aspect of the hemisphere; the cingulate gyrus is located im-

of the hemisphere immediately superior to the corpus callosum.

mediately adjacent to the corpus callosum. None of the other

The internal cerebral vein (to the great cerebral vein) drains the

lobes of the cerebral cortex borders directly on the corpus callo-

internal parts of the hemisphere; the ophthalmic vein connects the

sum. (p. 13, 28)

orbit with the cavernous sinus; and the superior petrosal sinus

connects the cavernous sinus with the sigmoid sinus at its junction

15.

Answer B: The inferior frontal gyrus consists of the pars or-

with the transverse sinus. (p. 19, 23, 29)

bitalis (Brodmann area 47), pars triangularis (area 45), and pars

opercularis (area 44). A lesion located primarily in areas 44 and

22.

Answer A: As they descend in the dural sac from their origin

45 in the dominant hemisphere will result in a nonfluent (Broca)

from the spinal cord to their exit at their respective intervertebral

aphasia. The supramarginal (area 40) and angular (area 39) gyri

foramen, the anterior and posterior roots form the cauda equina.

represent what is called the Wernicke area, and the middle frontal

The conus medullaris is the most caudal end of the spinal cord, and

gyrus contains areas 6 and 8. The lateral one-third of the precen-

the filum terminale internum is the strand of pia that extends from

tral gyrus is the face area of the somatomotor cortex. (p. 14)

the conus caudally to attach to the inner aspect of the dural sac at

about S2. The denticulate ligament anchors the spinal cord later-

16.

Answer A: Areas 3, 1, 2 collectively represent the primary so-

ally to the inner surface of the dural sac, and the filum terminale

matosensory cortex. Area 4 is the primary somatomotor cortex,

externum anchors the dural sac caudally to the inner aspect of the

area 17 the primary visual cortex, and area 22 the primary audi-

coccyx. (p. 12, 85, 87)

tory cortex. Area 40 is in the supramarginal gyrus, a large part of

which is called the Wernicke area. (p. 14)

23.

Answer B: The primary somatomotor cortex consists of the

precentral gyrus and the anterior paracentral gyrus; area 4 is found

17.

Answer D: The body is represented in the somatomotor cortex

in these structures. Areas 3, 1, and 2 are the primary somatosen-

(precentral gyrus, anterior paracentral gyrus) in the following pat-

sory cortex; areas 5 and 7 make up the superior parietal lobule and

tern: the face in about the lateral one-third of the precentral gyrus

the precuneus; and area 6 is located rostral to area 4. Portions of

above the lateral sulcus; the hand and upper extremity in about its

area 6 in the caudal region of the middle frontal gyrus are the

middle third; and the trunk and hip in about its medial third. The

frontal eye field. (p. 15)

lower extremity and foot are represented in the anterior paracen-

tral gyrus. Caudal portions of the middle frontal gyrus are the lo-

24.

Answer A: In this patient, the meningioma is located in the falx

cation of the frontal eye field. (p. 15)

cerebri and is impinging on the anterior paracentral gyrus corre-

lating with her motor deficit. The lower extremity is represented

18.

Answer C: The L4-L5 interspace is commonly used for a lum-

in the anterior paracentral gyrus (somatomotor) and in the poste-

bar puncture. The L3-L4 space may also be used. Levels T12 to

rior paracentral gyrus (somatosensory). The precentral gyrus con-

L2-L3 are too high. Because the caudal end of the spinal cord (the

tains the motor representation for the face (lateral part) and the

conus medullaris) may be as low as L2 in some individuals, levels

trunk and hip (medial part). The postcentral gyrus is part of the

T12-L1 to L2-L3 are not used, as this would most likely result in

somatosensory cortex. (p. 15)

damage to the spinal cord. The S1-S2 vertebrae are fused so there

is no intervertebral space through which a needle can pass. Fur-

25.

Answer D: The M₄ segments of the middle cerebral artery serve

thermore, the dural sac ends at about S2. (p. 12)

the lateral aspect of the cerebral hemisphere. The named M₄ ves-

sels that serve the pre- and postcentral gyri (hemorrhage into ap-

19.

Answer B: The oculomotor nerve (III) exits from the medial as-

proximately the lower two-thirds of these gyri explain the motor

pect of the midbrain into the interpeduncular fossa/cistern. It tra-

and sensory deficits) are the precentral branches (prerolandic),

verses this space, courses through the lateral wall of the cavernous

central branches

(Rolandic branches), and anterior parietal

sinus to eventually enter (along with the trochlear [IV] and ab-

branches. The M₂ segment serves the insular cortex, and the M₃

ducens [VI] nerves) the superior orbital fissure. Cranial nerves IV,

segment serves the inner surface of the frontal, parietal, and tem-

VI, and V₁ (the ophthalmic portion of the trigeminal nerve), along

poral opercula. The A₁ segment serves hypothalamic structures,

with III, pass through the cavernous sinus. Cranial nerve II (optic)

the subcallosal and septal areas, and adjacent structures. P₄ serves

is quite rostral to the interpeduncular fossa. (p. 24, 30, 40)

the medial aspect of the occipital lobe (visual cortex). (p. 19, 29)

20.

Answer D: A lesion in area 44 (the pars opercularis) that spreads

will affect the lower portions of the precentral gyrus in which the

26.

Answer E: The uncus is a small elevation at the rostral and me-

face is represented. This will result in weakness of facial muscles,

dial aspect of the parahippocampal gyrus adjacent to the crus cere-

accompanied by other cranial nerve deficits. The cortical areas for

bri of the midbrain. In addition to the catastrophic effect of de-

hearing and vision are far separated from area 44. Also, a lesion in

cerebration, herniation of the uncus may also affect corticospinal

the primary auditory cortex will not result in a hearing loss in one

and corticonuclear (corticobulbar) fibers in the crus cerebri and

ear. The hand area of the sensory cortex and the upper extremity

the root of the oculomotor nerve. None of the other areas of the

area of the motor cortex are not adjacent to Brodmann area 44.

forebrain listed as choices is related to uncal herniation. (p. 20, 22)

(p. 14)

27.

Answer E: The P₄ segments of the posterior cerebral artery con-

21.

Answer D: The superficial middle cerebral vein is located on the

sist of the parieto-occipital and calcarine branches; the latter being

surface of the cerebral hemisphere in the immediate vicinity of the

located in the calcarine sulcus and a primary blood supply to the

lateral sulcus and, of the choices, is the most likely candidate. The

primary visual cortex. M₃ and M₄ segments of the middle cerebral

deep middle cerebral vein is located on the surface of the insular

are located, respectively, on the inner aspect of the frontal, pari-

lobe. The inferior sagittal sinus primarily drains the medial aspect

etal, and temporal opercula and on the lateral aspect of the cere-

260

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

bral hemisphere. The P

34.

Answer E: Cerebrospinal fluid in the ventricles, and throughout

2segment of the posterior cerebral artery is

located just distal to the posterior communicating-posterior cere-

the subarachnoid space, appears very white in T₂-weighted MRI

bral intersection and gives rise to medial and lateral posterior

images. Structures located in, or traversing the subarachnoid

choroidal and to thalamogeniculate arteries. The A₁ segment is lo-

space (such as vessels or cranial nerve roots, including the oculo-

cated between the internal carotid and anterior communicating

motor nerve) appear grey to black against a white background. (p.

artery and gives rise to branches that serve anterior hypothalamic

46-47, 49, 51, 54)

structures, septal areas, and the optic chiasm. (p. 21, 29)

35.

Answer A: Cerebrospinal fluid, and other fluids, appear black in

28.

Answer B: The glomus choroideum is found in the atrium of the

T1-weighted MRI images. Consequently, the ventricles, and more

lateral ventricle. This part of the choroid plexus is rostrally contin-

obvious parts of the subarachnoid space, appear black. Changes in

uous with that in the body of the lateral ventricle and continuous

ventricular shape (i.e., enlargement, midline shift), or obliterated

anteroinferiorly with that in the temporal horn. The roof of the

sulci, or even subarachnoid space, most likely represent a poten-

third ventricle has a small portion of choroid plexus that is contin-

tially serious clinical issue. (p. 2-4, 33 as one example)

uous with that in the body of the ventricle via the interventricular

foramen. The anterior horn contains no choroid plexus. (p. 52)

36.

Answer E: Patients who experience rupture of an intracranial

aneurysm frequently complain of an intense, sudden headache

29.

Answer E: Trauma is the most common cause of subarachnoid

(“the most horrible headache I have ever had”). Acute blood in the

hemorrhage (SAH). The most common cause of spontaneous (also

subarachnoid space will appear white to very white on CT. This

called nontraumatic) SAH is bleeding from a ruptured aneurysm

will contrast with the medium grey of the brain and the black of

(about 75% of all spontaneous cases). Bleeding from an arteriove-

cerebrospinal fluid (CSF) in the ventricles. The degree of white

nous malformation (AVM) is an infrequent cause of SAH (about

may vary somewhat, based on the relative concentration of blood,

5% of cases), and bleeding from brain tumors into the subarach-

from very white (concentrated blood) to white (mostly blood,

noid space is rare. Meningiomas are usually slow-growing tumors

some CSF), to very light grey (mixture of blood and CSF). (p.

that may have a rich vascular supply but rarely hemorrhage spon-

46-47, 51)

taneously. (p. 46)

37.

Answer C: The hypoglossal nerve exits the medulla via the pre-

30.

Answer D: The prepontine cistern is located external to the

olivary sulcus of the medulla immediately (and laterally) adjacent

basilar pons and contains the abducens nerve, basilar artery, ori-

to the pyramid. The abducens nerve exits in line with the preoli-

gin of the anterior inferior cerebellar artery, and small perforating

vary sulcus, but, at the caudal edge of the pons, and the trigemi-

arteries and veins. The ambient cistern is located on the lateral as-

nal nerve exits the lateral aspect of the pons. The vagus nerve ex-

pect of the midbrain and contains the trochlear nerve and several

its the lateral aspect of the medulla via the postolivary sulcus, and

major arteries. The premedullary cistern is located at the anterior

the facial nerve in line with this sulcus, but at the pons-medulla

surface of the medulla and contains the anterior spinal artery. The

junction. (p. 24, 44)

inferior cerebellopontine cistern contains the glossopharyngeal,

vagus, and accessory nerves. The superior cerebellopontine cis-

38.

Answer E: Approximately one-half of cases of bacterial menin-

tern contains the trigeminal, facial, and vestibulocochlear nerves

gitis in adults are caused by S. pneumoniae. E. coli and L. monocyto-

plus a short segment of the trochlear nerve. (p. 50, 51)

genes are causative agents in neonates and children, although the

latter (L. monocytogenes) is present in less than 10% of cases. While

31.

Answer B: Lenticulostriate arteries, also called the lateral stri-

H. influenzae was a major cause of bacterial meningitis in children,

ate arteries, originate from the M₁ segment of the middle cerebral

the use of a vaccine has reduced this bacterium as a causative agent

artery and serve much of the lenticular nucleus and adjacent parts

to well under 10% of cases. H. simplex is a virus. (p. 46)

of the internal capsule. A₁ branches serve the anterior hypothala-

mus and optic chiasm, and M₂ branches serve the insular cortex.

39.

Answer D: The trochlear nerve exits the posterior (dorsal) as-

The P₁ and P₂ segments give rise to many small perforating

pect of the brainstem just caudal to the inferior colliculus and

branches and to the thalamoperforating and quadrigeminal arter-

passes around the lateral aspect of the midbrain in the ambient cis-

ies (P₁), medial and lateral posterior choroidal arteries, and the

tern, en route to its exit from the skull via the superior orbital fis-

thalamogeniculate artery (P₂). (p. 25, 49, 242)

sure. The abducens nerve exits at the caudal edge of the pons in

line with the preolivary fissure, and the hypoglossal exits from the

32.

Answer A: The gyrus rectus is located on the inferior and me-

medulla via this fissure. The trigeminal nerve exits the lateral as-

dial aspect of the frontal lobe. It is separated from the orbital gyri

pect of the pons, and the vestibulocochlear nerve exits at the most

by the olfactory sulcus in which the olfactory bulb and tract is lo-

lateral aspect of the pons-medulla junction. (p. 26, 33, 34)

cated. None of the other lobes has a direct relationship to the gyrus

rectus.

(p. 20, 22)

40.

Answer B: As it exits the anterior (ventral) surface of the mid-

brain, the oculomotor nerve passes between the superior cerebel-

33.

Answer B: The optic tract lies immediately on the surface of the

lar artery (which is caudal to the nerve root) and the P₁ segment

crus cerebri, a relationship frequently seen in MRI. The fact that this

of the posterior cerebral artery (which is rostral to the nerve root).

patient has a right-sided weakness of the extremities specifies that the

The trigeminal root is adjacent to more distal portions of the su-

lesion is in the left crus cerebri. The bilateral visual deficits correlate

perior cerebellar artery; the labyrinthine artery accompanies the

with damage to the left optic tract. Lesions of the left basilar pons and

vestibulocochlear nerve as it enters the internal acoustic meatus;

pyramid would result in a right-sided weakness but no visual deficits.

and the ophthalmic artery accompanies the optic nerve along part

A lesion in the right optic nerve would result in blindness in that eye

of its extent. The abducens nerve passes rostrally adjacent to the

but no weakness of the extremities. (p. 20, 26, 40, 220-221)

basilar artery in the prepontine cistern. (p. 25, 39, 40)

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

261

41.

Answer D: The rostral edge of the striae medullares (of the

Review and Study Questions for

fourth ventricle) is regarded as the border between the pontine

Chapters 3 and 4

and medullary portions of the fourth ventricle. These fibers pass

from the median fissure in the floor of the ventricle laterally into

A 47-year-old woman presents with signs of increased intracranial

the lateral recess where they arch up into the cerebellum. The fa-

pressure (vomiting, headache, lethargy). MRI shows a large tumor

cial colliculus and median eminence are located in the floor of the

invading the head of the caudate nucleus, the rostral portion of the

pontine portion of the ventricle, and the vagal and hypoglossal

putamen and involving a fiber bundle located between these two

trigones are found in the medial floor of the medullary portion of

structures. This fiber bundle is most likely the

the fourth ventricle. (p. 34, 35, 36)

(A) anterior commissure

42.

Answer D: The primary fissure is the deepest fissure in the cere-

(B) anterior limb of the internal capsule

bellum and it separates the anterior lobe from the posterior lobe

and extends from the vermis to the lateral cerebellar margin. The

(D) external capsule

posterolateral fissure is located between the flocculonodular lobe

(E) posterior limb of the internal capsule

and the posterior lobe. The horizontal, secondary, and posterior

superior fissures are all located within the posterior lobe. (p. 32,

A 76-year-old woman is diagnosed as having

“probable”

33)

Alzheimer’s disease based on a steady decline in cognitive func-

tion. It is likely that this woman has cell dropout in the nucleus ac-

43.

Answer C: The tonsil of the cerebellum is found on the caudal

cumbens. Which of the following most specifically describes the

and inferior aspect of the cerebellar hemisphere, adjacent to the

location of this cell group?

midline and immediately posterior (dorsal) to the medulla. The

(A) At the junction of the caudate head and putamen

cisterna magna is located in this area. Sudden tonsillar herniation

(B) At the junction of the pallidum and putamen

may compress the medulla and damage respiratory and cardiac

centers resulting in sudden death. The tonsil herniates downward

(D) In the anterior wall of the temporal horn

through the foramen magnum. Consequently, no other part of the

(E) Internal to the uncus

brainstem is directly affected. (p. 32, 44)

Which of the following structures is located in the medial wall of

44.

Answer A: A CT is a fast method, does not require sedation of

the temporal horn of the lateral ventricle and, if severely dam-

young patients, and shows bone fractures and acute intracranial

aged, may result in memory deficits?

blood in detail. MRI (T1- and T2-weighted) does not show acute

(A) Amygdaloid complex

blood or bone fracture to advantage, takes much longer to do, and

(B) Calcar avis

may require sedation in a child. Enhanced MRI is uniquely useful

for tumors, and PET is useful in identifying metabolic activity of

(D) Pulvinar

brain tissue, not anatomic detail. (p. 4-6)

(E) Tail of the caudate

45.

Answer B: The long and short gyri (gyri longi et breves) are

Which of the following represents the fibers that fan out from the

components of the insular lobe. This lobe is located deep to the

internal capsule into the white matter of the hemisphere?

lateral sulcus, has a central sulcus that separates the short gyri (ros-

(A) Cingulum

tral to this sulcus) from the long gyri (caudal to this sulcus). The

(B) Corona radiata

cortex of the insular lobe is separated from the adjacent frontal,

parietal, and temporal opercula by the circular sulcus of the insula.

(D) Superior longitudinal fasciculus

None of the other lobes has gyri that are specifically named long

(E) Uncinate fasciculus

and short gyri. (p. 13, 45, 56)

The lamina of white matter located immediately internal to the

46.

Answer C: The glossopharyngeal nerve contains the afferent

cortex of the insula is the:

limb of the gag reflex and, through its innervation of the stylopha-

ryngeus muscle, is an important part of the efferent limb of this

(A) Arcuate fasciculus

reflex. The nucleus ambiguus, the location of the motor neurons

(B) External capsule

serving the stylopharyngeus, also contributes to the innervation of

muscle served by the vagus nerve and, therefore, to the efferent

(D) Internal capsule

limb of the gag reflex. The trigeminal and facial nerves participate

(E) Tapetum

in the afferent and efferent limbs (respectively) of the corneal re-

flex. The accessory nerve innervates the ipsilateral trapezius and

A 48-year-old man presents with a movement disorder (chorea)

sternocleidomastoid muscles, and the hypoglossal nerve inner-

and mental deterioration. MRI shows the loss of a structure in the

vates the ipsilateral genioglossus muscle. (p. 24, 43)

wall of the anterior horn of the lateral ventricle. Which of the fol-

lowing is most likely lost in this patient?

(A) Anterior thalamic nucleus

(B) Body of the caudate nucleus

(D) Dorsomedial nucleus

(E) Head of the caudate nucleus

262

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

A 76-year-old man presents with a resting tremor, bradykinesia,

13.

A 29-year-old woman presents with neurologic deficits that wax and

and stooped posture. These observations suggest loss of a promi-

wane over time suggestive of multiple sclerosis. MRI (especially T2-

nent population of cells in the brain. Which of the following struc-

weighted) shows small, demyelinated areas at several locations in

tures is most likely affected in this patient?

her brain, one of these being the mammillothalamic tract. Which of

the following structures is most intimately associated with this tract?

(A) Lateral cerebellar nucleus

(B) Locus ceruleus

(A) Anterior thalamic nucleus

(B) Centromedian nucleus

(D) Substantia nigra

(E) Subthalamic nucleus

(D) Ventral anterior thalamic nucleus

(E) Ventral lateral thalamic nucleus

Which of the following represents the larger, more laterally lo-

cated portion of the basal nuclei (also called the basal ganglia)?

14.

Which of the following structures is a primary target of the optic

tract as it passes caudally from the optic chiasm?

(A) Caudate nucleus

(B) Globus pallidus

(A) Lateral geniculate nucleus

(B) Mammillary body

(D) Subthalamic nucleus

(E) Substantia nigra

(D) Pulvinar

(E) Ventral posterolateral nucleus

The MRI of a 59-year-old woman shows a large arteriovenous

malformation (AVM) located between the lenticular nucleus and

15.

An 82-year-old man presents with a severe motor deficit (resting

the dorsal thalamus. Based on its location, this AVM most likely

tremor) and dementia. The former correlates with degenerative

involves which of the following structures?

changes in the putamen and globus pallidus and the latter with de-

generative changes in the ventral striatum and ventral pallidum.

(A) Anterior limb of the internal capsule

Which of the following structures separates these two areas in the

(B) Crus cerebri

basal forebrain?

(D) Posterior limb of the internal capsule

(A) Anterior commissure

(E) Retrolenticular limb of the internal capsule

(B) Lamina terminalis

10.

A 29-year-old man is brought to the emergency department with

(D) Posterior commissure

a severe and persistent headache. MRI shows a large tumor of the

(E) Septum pellucidum

pineal gland. Based on its location, this pineal lesion would most

likely impinge on which of the following structures?

16.

A 23-year-old man is brought to the emergency department by

emergency medical personnel after an automobile collision. CT

(A) Anterior thalamic nucleus

shows bilateral damage to the temporal pole and the uncus. Which

(B) Body of the caudate nucleus

of the following structures is also most likely damaged in this patient?

(D) Pulvinar nucleus(i)

(A) Amygdaloid complex

(E) Ventral posteromedial nucleus

(B) Anterior thalamic nucleus

11.

The hippocampal commissure contains fibers from one hippocam-

(D) Gracile nucleus

pal formation that cross the midline to distribute to targets on the

(E) Hippocampal formation

opposite side of the hemisphere. Which of the following struc-

tures is directly adjacent to this commissure?

17.

The optic radiations are closely associated with which of the fol-

lowing spaces?

(A) Body of the corpus callosum

(B) Genu of the corpus callosum

(A) Anterior horn of the lateral ventricle

(B) Body of the lateral ventricle

(D) Spiral fibers of the hippocampus

(E) Precommissural fornix

(D) Posterior horn of the lateral ventricle

(E) Third ventricle

12.

An 85-year-old woman is brought to the emergency department

by her family because she suddenly became confused and lethar-

18.

A 31-year-old man presents with ill-defined neurologic com-

gic. CT shows a hemorrhage into the medial and lateral geniculate

plaints (persistently tired, headache, confusion). CT shows an ar-

bodies. Which of the following structures would also likely be in-

teriovenous malformation occupying most of the dorsomedial nu-

volved in this lesion due to its apposition to the geniculate bodies?

cleus (DM) of the thalamus. Which of the following structures

separates the DM from the lateral thalamic nuclei and encom-

(A) Anterior thalamic nucleus

passes the centromedial nucleus?

(B) Rostral dorsomedial nucleus

(A) Ansa lenticularis

(D) Pulvinar nucleus(i)

(B) External medullary lamina

(E) Subthalamic nucleus

(D) Lamina terminalis

(E) Stria medullaris thalami

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

263

19.

A 48-year-old woman presents with violent, flailing movements

Answer C: The layer of white matter located internal to the in-

of her left upper extremity. CT shows a small hemorrhage in the

sular cortex, and external to the claustrum, is the extreme cap-

subthalamic nucleus. Which of the following structures is located

sule. The external capsule is found between the claustrum and the

directly adjacent to the subthalamic nucleus?

putamen, and the internal capsule is a large bundle of fibers located

primarily between the lenticular nucleus on one side and the head

(A) Centromedian nucleus

of the caudate and the diencephalon on the other side. The tape-

(B) Globus pallidus

tum is located in the lateral wall of the posterior horn of the lat-

eral ventricle. Arcuate fasciculi are small bundles of fibers passing

(D) Putamen

between gyri. (p. 65, 67-68, 77)

(E) Substantia nigra

Answer E: The large bulge in the lateral wall of the anterior horn

20.

Which of the following structures is located immediately caudal to

of the lateral ventricle is the head of the caudate nucleus. The po-

the anterior commissure and appears as a distinct black spot in a

sition of the interventricular foramen represents the point at which

T2-weighted axial MRI?

the head of the caudate becomes the body of the caudate. The dor-

(A) Anterior limb of internal capsule

somedial nucleus borders on the third ventricle; the anterior thal-

(B) Column of the fornix

amic nucleus is located at the rostral end of the diencephalon and is

caudomedial to the interventricular foramen; and the column of

(D) Lenticular fasciculus

the fornix is rostromedial to this foramen. (p. 64-65, 76)

(E) Mammillothalamic tract

Answer D: These deficits are characteristic of Parkinson’s dis-

ease and are directly correlated with loss of the dopamine (and

melanin)-containing cells of the substantia nigra of the midbrain.

Answers for Chapters 3 and 4

The locus (nucleus) ceruleus, also called the nucleus pigmentosus

pontis, also contains cells with melanin, but loss of these cells does

Answer B: The anterior limb of the internal capsule is insinu-

not cause motor deficits. The other choices do not contain pig-

ated between the head of the caudate nucleus and the rostral as-

mented cells, but damage to these structures does cause a differ-

pect of the lenticular nucleus, mostly the putamen. The posterior

ent series of motor deficits. (p. 68-69, 78)

limb is between the lenticular nucleus and the thalamus; the col-

umn of the fornix is rostromedial to the interventricular foramen;

Answer C: The putamen is the most lateral part of the basal nu-

and the anterior commissure traverses the midline at the level of

clei; taken together, the putamen and the globus pallidus comprise

the genu of the internal capsule. The external capsule is a thin

the lenticular nucleus. The caudate nucleus, specifically its head

sheet of white matter lateral to the lenticular nucleus and medial

and body portions, is located medial to the internal capsule. While

to the claustrum. (p. 64-65, 76-77)

the subthalamic nucleus and the substantia nigra function in con-

cert with the basal nuclei, these structures are medially located

Answer A: The nucleus accumbens is located in the rostral and

and are not part of the basal nuclei. (p. 65-68, 76)

basal forebrain at the point where the head of the caudate is con-

tinuous with the putamen. The amygdaloid nucleus is located in-

Answer D: The posterior limb of the internal capsule, contain-

ternal to the uncus and in the anterior wall of the temporal horn.

ing important cortical afferent and efferent fibers, is located be-

The pallidum (globus pallidus) and the substantia nigra do not have

tween the lenticular nucleus and the dorsal thalamus. Damage to

a continuum with the nucleus accumbens. (p. 64, 78)

this structure may result in sensory and/or motor deficits on the

opposite side of the body. The anterior limb is located between

Answer C: The hippocampal formation, commonly called the

the head of the caudate and the putamen, while the retrolenticu-

hippocampus, is located in the medial wall of the temporal (infe-

lar limb is found caudal to the lenticular nucleus. The crus cerebri

rior) horn of the lateral ventricle. Damage to the hippocampus

is on the inferolateral aspect of the midbrain. The external capsule

may result in memory problems. The amygdaloid complex is lo-

is lateral to the putamen. (p. 67-69, 76-77)

cated in the rostral wall of the temporal horn, the tail of the cau-

date in its lateral wall, and the calcar avis (also called the calcarine

10.

Answer D: The pineal gland is located in the quadrigeminal cis-

spur, a ridge in the wall of the posterior horn indicating the depth

tern, superior to the colliculi, and between the pulvinar nuclei of

of the calcarine sulcus) is in the medial wall of the posterior horn

the thalamus. At this location, the lesion would potentially involve

of the lateral ventricle. The pulvinar is part of the diencephalon.

the colliculi and pulvinar. The other thalamic nuclei are not adja-

(p. 58, 68-71)

cent to the pineal, the globus pallidus is lateral to the posterior

limb of the internal capsule, and the body of the caudate is located

Answer B: The corona radiata (radiating crown) are those fibers

in the lateral wall of the body of the lateral ventricle. (p. 71)

of the internal capsule that fan out in all directions from its supe-

rior edge. These fibers contain a variety of fibers traveling to and

11.

Answer C: The hippocampal commissure is located immedi-

from the cerebral cortex. The superior longitudinal and uncinate

ately inferior to the splenium of the corpus callosum; the crossing

fasciculi are organized bundles of corticocortical fibers on the ip-

of these fibers takes place at this point. Other parts of the corpus

silateral side, and the cingulum is a fiber bundle located internal to

callosum are not related to the hippocampal commissure, and the

the cingulate cortex. The fibers of the genu of the corpus callo-

spiral fibers of the hippocampus are bundles within the hippocam-

sum contain corticocortical fibers that pass between the cerebral

pal formation in the temporal lobe. Some of the fibers in the hip-

hemispheres. (p. 57, 65-69)

pocampal commissure enter the precommissural fornix, but by no

means all. (p. 72)

264

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

12.

Answer D: The geniculate bodies are tucked-up under the cau-

18.

Answer C: The internal medullary lamina is a vertically ori-

dal and inferior aspect of the pulvinar. The groove between the

ented sheet of fibers that extends from the rostral portion of the

medial geniculate body and the pulvinar contains the brachium of

thalamus caudally to surround the centromedian nucleus; this nu-

the superior colliculus. The geniculate bodies and the pulvinar

cleus is frequently referred to as “in” the internal medullary lam-

have a common blood supply from the thalamogeniculate artery,

ina due to its position. This lamina separates the dorsomedial nu-

a branch of P₂. None of the other choices have a close apposition

cleus from the laterally adjacent ventral anterior, ventral lateral,

with the geniculate bodies. The anterior thalamic, rostral dorso-

and ventral posterolateral nuclei. The external medullary lamina

medial, and subthalamic nuclei do not share a common blood sup-

is located between the thalamus and the posterior limb of the in-

ply with the pulvinar. (p. 58-59, 70)

ternal capsule, and the lamina terminalis is the rostral wall of the

third ventricle. The stria medullaris is a small bundle of fibers pass-

13.

Answer A: The mammillothalamic tract extends from the

ing rostrocaudally along the upper medial edge of the thalamus

mammillary bodies to the anterior nucleus of the thalamus; the

from the general location of the interventricular foramen to the

cells of origin are in the mammillary nuclei and the axons termi-

habenula, and the ansa lenticularis contains pallidothalamic fibers.

nate in the anterior nucleus. This tract is frequently visible in ax-

(p. 68-69, 76, 144-149, 162)

ial T2-weighted MRI. The ventral anterior nucleus is laterally ad-

jacent to the mammillothalamic tract, but does not receive input

19.

Answer E: The subthalamic nucleus is separated from the sub-

therefrom. The other choices are nuclei located more caudally in

stantia nigra by only a thin layer of myelinated fibers; these two

the diencephalon. (p. 67, 77)

structures are directly adjacent to each other. Damage to the sub-

thalamic nucleus gives rise to hemiballistic movements (described

in this question) while loss of cells in the substantia nigra results in

14.

Answer A: Many of the fibers contained in the optic tract ter-

the motor deficits seen in Parkinson’s disease. The putamen,

minate in the lateral geniculate nucleus. Some of these fibers by-

globus pallidus, and the medial geniculate nucleus are all lateral to

pass this nucleus to traverse the brachium of the superior collicu-

the internal capsule; the subthalamic nucleus is medial. The cen-

lus and a few enter the suprachiasmatic nucleus. The medial

tromedial nucleus is separated from the subthalamic nucleus by

geniculate nucleus receives input via the brachium of the inferior

other thalamic nuclei. (p. 68-69, 148-149)

colliculus (auditory); the pulvinar has interconnections with the

visual cortex and superior colliculus; and the ventral posterolat-

20.

Answer B: The column of the fornix is that portion of this

eral nucleus receives input from the anterolateral system and the

fiber bundle that arches around the rostromedial end of the thal-

medical lemniscus. The mammillary body is located rostral to the

amus. As it does so, the column joins its counterpart on the op-

interpeduncular fossa and medial to the optic tract. (p. 58, 59)

posite side and “leans against” the anterior commissure. The col-

umn of the fornix also signifies, in cross section or axial planes,

15.

Answer A: The anterior commissure, as it passes laterally from

the laterally adjacent interventricular foramen and genu of the

the midline, separates the dorsal basal nuclei (putamen and globus

internal capsule. The mammillothalamic tract is located caudal

pallidus) from the ventral striatum and ventral pallidum. The pos-

to the fornix, and the crus of the fornix is found along the mid-

terior commissure is located at the caudal aspect of the third ven-

line superior to the thalamus. The anterior limb of the internal

tricle just above the opening of the cerebral aqueduct, and the

capsule is found between the head of the caudate nucleus and the

Massa intermedia bridges the third ventricle in about 80% of indi-

lenticular nucleus (mainly the putamen). The lenticular fascicu-

viduals. The rostral wall of the third ventricle is formed by the

lus contains pallidothalamic fibers and traverses the posterior

lamina terminalis and the septum pellucidum forms the medial

limb of the internal capsule en route to the dorsal thalamus. (p.

wall of the anterior horn of the lateral ventricle. (p. 65, 152-153)

31, 77, 163-164)

16.

Answer A: The amygdaloid complex is located immediately in-

ternal to the uncus. Bilateral damage to rostral portions of the

temporal lobe may include the amygdala and result in a constella-

Review and Study Questions for

tion of deficits known as the Klüver-Bucy syndrome. The hip-

Chapter 5

pocampal formation is internal to the cortex of the parahip-

pocampal gyrus, and the anterior thalamic nucleus is internal to

A 16-year-old boy is brought to the emergency department fol-

the anterior thalamic tubercle. The cingulate gyrus overlies the

lowing a diving accident at a local quarry. The examination reveals

longitudinally oriented fibers of the cingulum and the gracile tu-

a bilateral loss of motor and sensory function in the trunk and

bercle is the external elevation formed by the gracile nucleus. (p.

lower extremities. At 36 hours after the accident the boy is able

58-59, 65-66, 78, 170)

to dorsiflex his toes, barely move his right lower extremity at the

knee, and is able to perceive pinprick stimulation of the perianal

17.

Answer D: The optic radiations are located in the lateral wall of

skin (sacral sparing). Which of the following most specifically de-

the posterior horn of the lateral ventricle as they pass through the

scribes the spinal cord lesion in this patient?

retrolenticular limb of the internal capsule from the lateral genic-

ulate nucleus to the primary visual cortex. A thin layer of white

(A) Central cord

matter, the tapetum, separates the optic radiations from the wall

(B) Complete

of the ventricle. The cisterns at the midbrain on the basal aspect of

the hemisphere contain the optic tract. The other ventricular

(D) Incomplete

spaces listed have no direct relationship to the optic radiations. (p.

(E) Large syringomyelia

71-72, 77, 138-141, 162)

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

265

A 54-year-old morbidly obese and hypertensive man is brought to

Which of the following represents the most likely level of damage

the emergency department after experiencing sudden onset of

to the spinal cord resulting from the fracture to the vertebral col-

weakness of his left upper and lower extremities. CT shows an in-

umn in this man?

farcted area in the medulla. Damage to which of the following

(A) T6 on the left

tracts or fiber bundles of the medulla would most likely explain

(B) T8 on the left

this deficit?

(A) Anterolateral system

(D) T10 on the left

(B) Corticospinal fibers

(E) T10 on the right

(D) Rubrospinal tract

The artery of Adamkiewicz is an especially large spinal medullary

(E) Vestibulospinal fibers

artery supplementing the arterial blood supply to the spinal cord.

Which of the following represents the most consistent location of

this vessel?

A 78-year-old healthy, active woman experiences a sudden weak-

(A) At C7-C8 on the left

ness of her right upper extremity during an angiogram to deter-

(B) At L5-S1 on the left

mine the patency of her carotid bifurcation. The immediate ex-

amination reveals weakness of both extremities on the right and a

(D) At T6-T7 on the right

partial loss of vision in both eyes (homonymous hemianopsia).

(E) At T12-L1 on the left

These observations suggest an embolic stroke resulting in a lesion

involving motor and visual structures. The infarcted area in CT

The CT of a 73-year-old woman shows an infarcted area in the ros-

points to the occlusion of one vessel. Which of the following ves-

tral portions of the dorsomedial nucleus, the anterior nucleus, and

sels is most likely occluded?

the ventral anterior nucleus. Which of the following arteries sup-

(A) Anterior cerebral artery

ply blood to this area of the brain?

(B) Anterior choroidal artery

(A) Anterior choroidal

(B) Lateral striate (lenticulostriate)

(D) Lateral posterior choroidal artery

(E) Posterior cerebral artery (P3 and P4 segments)

(D) Thalamogeniculate

(E) Thalamoperforating

A 69-year-old man is brought to the emergency department by his

wife after complaining of a bad headache and becoming stuporous.

Which of the following structures is insinuated between the ex-

CT shows a hemorrhage into the head of the caudate nucleus that

ternal and extreme capsules and is functionally related to the in-

has ruptured into the anterior horn of the lateral ventricle. This

sular cortex?

hemorrhage has most likely originated from which of the follow-

(A) Claustrum

ing vessels?

(B) External medullary lamina

(A) Anterior choroidal artery (branch of internal carotid)

(D) Putamen

(B) Lenticulostriate branches (of M1)

(E) Stria terminalis

(D) Medial striate artery (branch of A2)

10.

An 83-year-old man is brought to the emergency department by his

(E) Thalamoperforating artery(ies)

daughter, who explains that her father started having “fits”. The ex-

amination reveals an alert, otherwise healthy, man who frequently

Questions 5 and 6 are based on the following patient.

has uncontrollable flailing movements of his left arm. Which of the

A 23-year-old man is brought to the emergency department from the

following structures is most likely involved in this lesion?

site of an automobile collision. The neurologic examination reveals

(A) Cerebellar cortex plus nuclei

weakness of the right lower extremity and a loss of pain and thermal

(B) Lenticular nucleus

sensations on the left side beginning at the level of the umbilicus. CT

shows a fracture of the vertebral column with displacement of bone

(D) Ventral lateral nucleus

fragments into the vertebral canal.

(E) Ventral posterolateral nucleus

11.

A 17-year-old girl presents with a bilateral loss of pain and ther-

5. Damage to which of the following tracts would correlate with

mal sensations at the base of the neck (C3 dermatome) and ex-

weakness of the lower extremity in this man?

tending over the upper extremity and down to the level of the nip-

(A) Left lateral corticospinal tract

ple (C4 to T4 dermatomes). MRI shows a cavitation in the spinal

(B) Reticulospinal fibers on the right

cord at these levels. Damage to which of the following structures

would most likely explain this deficit?

(D) Right rubrospinal tract

(A) Anterior white commissure

(E) Vestibulospinal fibers on the right

(B) Left anterolateral system

(D) Posterior columns

(E) Right anterolateral system

266

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

12.

Which of the following structures is located within the territory

17.

A 92-year-old woman is brought to the emergency department by

of the medulla that is served by the anterior spinal artery?

her caregiver. The woman had suddenly become drowsy and con-

fused. The examination revealed no cranial nerve deficits and age-

(A) Anterolateral system

normal motor function, but a loss of pain, thermal, vibratory, and

(B) Gracile fasciculus

discriminative touch sensations on one side of the body excluding

the head. CT shows a small infarcted area. Which of the following

(D) Rubrospinal tract

structures is the most likely location of this lesion?

(E) Spinal trigeminal tract

(A) Anterolateral system

(B) Medial geniculate nucleus

13.

A 59-year-old man complains to his family physician that he has

trouble chewing. The examination reveals a weakness of mastica-

(D) Ventral posterolateral nucleus

tory muscles on the left side. Which of the following nuclei is

(E) Ventral posteromedial nucleus

specifically related to the deficit seen in this man?

18.

In its location immediately internal to the anterior spinocerebel-

(A) Left facial motor

lar tract, which of the following fiber bundles would most likely

(B) Left hypoglossal

be damaged in a lesion to this area of the spinal cord?

(D) Right facial motor

(A) Anterolateral system

(E) Right trigeminal motor

(B) Anterior corticospinal tract

(D) Cuneate fasciculus

14.

A 15-year-old boy with signs of increased intracranial pressure

(E) Lateral corticospinal tract

(stupor, vomiting, headache) is referred to a neurologist. The ex-

amination reveals a paralysis of upward gaze, and MRI shows a

19.

A 37-year-old man is brought to the emergency department with

large tumor of the pineal gland. Damage to which of the follow-

a severe head injury. Within a few hours he is decerebrate (upper

ing structures would be most specifically related to the gaze

and lower extremities extended) and comatose. The extension of

deficit?

his extremities indicates a dominant input to extensor motor neu-

rons through vestibulospinal and reticulospinal fibers/tracts.

(A) Exit of the trochlear nerve

Which of the following most specifically describes the position of

(B) Inferior colliculus

these activated fibers within the spinal cord?

(D) Posterior commissure

(A) Anterolateral area (area of anterolateral system)

(E) Superior colliculus

(B) Posterolateral area (area of lateral corticospinal tract)

(D) Posterolateral (dorsolateral) tract

15.

A 61-year-old man is brought to the emergency department after

(E) Intermediate zone

a fall from his garage roof. The examination reveals a hemiplegia

on the left, a loss of vibratory sense on the left, and a loss of pain

Question 20 and 21 are based on the following patient.

and thermal sensation on the right side involving the upper and

A 71-year-old woman presents to her family physician with the com-

lower extremities. These deficits are characteristically seen in

plaint that “food dribbles out of my mouth when I eat”. The examina-

which of the following syndromes?

tion reveals a unilateral weakness of muscles around the eye (palpebral

(A) Benedikt

fissure) and the opening of the mouth (oral fissure). She also has a loss

(B) Brown-Séquard

of pain and thermal sensations on the opposite side of the body ex-

cluding the head. CT shows an infarcted area in the lateral portion of

(D) Wallenberg

the pontine tegmentum.

(E) Weber

20. Damage to which of the following nuclei would most likely ex-

plain the muscle weakness experienced by this woman?

16.

Based on their relative locations in the spinal cord, which of the

(A) Abducens

following tracts or fiber bundles would most likely be involved in

(B) Arcuate

a lesion located in the immediate vicinity of the lateral corti-

cospinal tract?

(D) Hypoglossal

(A) Anterolateral system

(E) Trigeminal motor

(B) Anterior spinocerebellar tract

21. The loss of pain and thermal sensations experienced by this woman

(D) Medial longitudinal fasciculus

would most likely correlate with a lesion involving which of the

(E) Rubrospinal tract

following structures?

(A) Anterior (ventral) trigeminothalamic tract

(B) Anterolateral system

(D) Medial lemniscus

(E) Spinal trigeminal tract

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

267

22.

A 77-year-old woman is discovered slumped on the floor in the gro-

28.

A 67-year-old woman is brought to the emergency department.

cery store; emergency medical personnel transport her to a local

She is stuporous and has signs that suggest a lesion in the brain-

hospital. The examination reveals a drowsy somewhat stuporous

stem; CT confirms this. Her right pupil is constricted (small)

woman who is difficult to arouse. CT shows a large hemorrhage

when compared with the left. Damage to which of the following

within the brain medial to the internal medullary lamina. Which of

tracts or fiber bundles in the pons or medulla would most likely

the following structures is most likely involved in this lesion?

explain this observation?

(A) Anterior thalamic nucleus

(A) Anterolateral system

(B) Dorsomedial nucleus

(B) Hypothalamospinal fibers

(D) Ventral lateral and anterior nuclei

(D) Reticulospinal fibers

(E) Ventral posterolateral nucleus

(E) Vestibulospinal fibers

23.

A 78-year-old man presents with deficits suggesting an occlusion

29.

In addition to the medial and lateral geniculate nuclei, which of the

of the posterior spinal artery at spinal cord levels C4-T2. Which

following structures is also served by the thalamogeniculate

of the following structures are in the territory served by this ves-

artery, a branch of P₂?

sel at these levels?

(A) Anterior thalamic nucleus

(A) Anterolateral system

(B) Globus pallidus

(B) Cuneate fasciculus

(D) Substantia nigra

(D) Lateral corticospinal tract

(E) Ventral anterior thalamic nucleus

(E) Medial longitudinal fasciculus

30. A 71-year- old man is brought to the emergency department by

24.

Based partially on their embryological origin from a common

his wife. She explains that he suddenly became weak in his left

group of cells, which of the following combinations of structures

lower extremity. She immediately rushed him to the hospital,

appear to be the same shade of grey in a T1- weighted MRI?

a trip of about 20 minutes. The examination reveals an alert

(A) Dorsomedial nucleus and Globus pallidus

man who is obese and hypertensive. He has no cranial nerve

(B) Globus pallidus and Caudate

deficits, is slightly weak on his left side, and has no sensory

deficits. Within 2 hours the weakness has disappeared. An MRI

(D) Putamen and Caudate nucleus

obtained the following day shows no lesions. Which of the fol-

(E) Putamen and Pulvinar

lowing most specifically describes this man’s medical experi-

ence?

25.

Which of the following portions of the trigeminal nuclear complex

(A) Central cord syndrome

is found in lateral areas of the brainstem between the level of the

(B) Small embolic stroke

obex and the spinal cord-medulla junction and is the source of

trigeminothalamic fibers conveying pain and thermal information

(D) Syringobulbia

originating from the face and oral cavity?

(E) Transient ischemic attack

(A) Mesencephalic nucleus

(B) Principal sensory nucleus

Questions 31 and 32 are based on the following patient.

A 41-year-old man is brought to the emergency department after an

(D) Spinal trigeminal nucleus, pars interpolaris

accident at a construction site. The examination reveals a weakness

(E) Spinal trigeminal nucleus, pars oralis

(hemiplegia) and a loss of vibratory sensation and discriminative touch

26.

Which of the following structures is located within the territory

all on the left lower extremity, and a loss of pain and thermal sensa-

served by branches of the posterior inferior cerebellar artery

tions on the right lower extremity. CT shows a fracture of the verte-

(commonly called PICA by clinicians)?

bral column adjacent to the T8 level of the spinal cord.

(A) Corticospinal fibers

31. Damage to which of the following fiber bundles or tracts would

(B) Hypoglossal root

most likely explain the loss of vibratory sensation in this man?

(D) Nucleus raphe magnus

(A) Anterolateral system on the right

(E) Solitary nucleus

(B) Cuneate fasciculus on the left

27.

Space-occupying lesions within the posterior cranial fossa, or

(D) Gracile fasciculus on the left

events that increase pressure within this infratentorial region, may

(E) Gracile fasciculus on the right

result in herniation of a portion of the cerebellum through the

foramen magnum. Which of the following parts of the cerebellum

32. The loss of pain and thermal sensation in this man reflects damage

is most likely involved in this event?

to which of the following fiber bundles or tracts?

(A) Anterior lobe

(A) Anterolateral system on the left

(B) Flocculus

(B) Anterolateral system on the right

(D) Simple lobule

(D) Gracile fasciculus on the left

(E) Tonsil

(E) Posterior spinocerebellar tract on the left

268

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

33.

Which of the following is the prominent population of melanin-

39.

Recognizing that this patient’s lesion involves the territory served

containing cells located immediately internal to the crus cerebri?

by paramedian branches of the basilar artery, which of the follow-

The loss of these cells may result in motor deficits.

ing structures is also most likely included in the area of infarction?

(A) Locus ceruleus

(A) Anterolateral system

(B) Pontine nuclei

(B) Facial motor nucleus

(D) Reticular formation

(D) Medial lemniscus

(E) Substantia nigra

(E) Spinal trigeminal tract

34.

Which of the following structures receives visceral sensory input

40.

A 77-year-old man presents with a weakness of his right upper and

and is located immediately inferior to the medial and spinal

lower extremities and he is unable to abduct his left eye on at-

vestibular nuclei at medullary levels?

tempted gaze to the left. Which of the following most specifically

(A) Cochlear nuclei

describes this deficit?

(B) Inferior salivatory nucleus

(A) Alternating hemianesthesia

(B) Hemihypesthesia

(D) Spinal trigeminal nucleus

(E) Solitary nucleus

(D) Middle alternating hemiplegia

35.

Which of the following groups of visceromotor (autonomic) cell

(E) Superior alternating hemiplegia

bodies is located lateral to the abducens nucleus, directly adjacent

to the exiting fibers of the facial nerve, and sends its axons out of

41.

In axial MRI which of the following structures is an important

the brainstem via this cranial nerve?

landmark that separates the third ventricle (rostral to this point)

(A) Dorsal motor nucleus

from the quadrigeminal cistern (caudal to this point)?

(B) Edinger-Westphal nucleus

(A) Lamina terminalis

(B) Habenular nucleus

(D) Intermediolateral cell column

(E) Superior salivatory nucleus

(D) Pulvinar

(E) Superior colliculus

36.

A 56-year-old woman presents to her family physician with per-

sistent headache and nausea. MRI shows a tumor in the fourth ven-

tricle impinging on the facial colliculus. Which of the following

42.

A 77-year-old woman presents with deficits that suggest a lesion

nuclei is found immediately internal to this elevation?

involving long tracts and a cranial nerve. CT shows an infarct in

the region served by the penetrating branches of the basilar bifur-

(A) Abducens

cation. Which of the following structures is most likely located in

(B) Facial

this vascular territory?

(D) Trigeminal

(A) Abducens nerve

(E) Vestibular

(B) Anterolateral system

Questions 37 through 39 are based on the following patient.

(D) Medial lemniscus

(E) Red nucleus

An 88-year-old man is brought to the emergency department by his

daughter. She indicates that he complained of weakness of his “arm”

Questions 43 through 46 are based on the following patient.

and “leg” (upper and lower extremities) on the right side and of “see-

ing two of everything” (double vision—diplopia). CT shows an in-

A 69-year-old man is brought to the emergency department with the

farcted area in the medial area of the pons at the pons-medulla junc-

complaint of a sudden loss of sensation. The history reveals that the

tion. The infarcted area is consistent with the vascular territory served

man is overweight, hypertensive, and does not regularly take medica-

by paramedian branches of the basilar artery.

tion. When the man speaks his voice is gravely and hoarse. The exam-

ination further reveals a loss of pain and thermal sensations on the right

37. Weakness of the extremities on the right can be explained by dam-

side of his body and on the left side of his face. CT shows an infarcted

age to which of the following structures?

area in the medulla.

(A) Corticospinal fibers on the left

(B) Corticospinal fibers on the right

43. Damage to which of the following structures would most likely

explain the man’s hoarse, gravely voice?

(D) Rubrospinal fibers on the left

(A) Facial nucleus

(E) Rubrospinal fibers on the right

(B) Gracile nucleus

38. The diplopia (double vision) this man is having is most likely the

result of damage to which of the following structures?

(D) Nucleus ambiguus

(E) Spinal trigeminal nucleus

(A) Abducens nerve root

(B) Facial nerve root

(D) Optic nerve

(E) Trochlear nerve or root

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

269

44.

Injury to which of the following structures in this man is most

50. An 82-year-old woman presents to the emergency department

specifically related to the loss of pain and thermal sensations on the

with difficulty swallowing (dysphagia). Which of the following nu-

body below the neck?

clei of the medulla contain motor neurons that innervate muscles

involved in swallowing?

(A) Anterolateral system

(B) Cuneate fasciculus

(A) Dorsal motor vagal

(B) Hypoglossal

(D) Medial lemniscus

(E) Spinal trigeminal tract

(D) Medial vestibular

(E) Nucleus ambiguus

45.

Damage to which of the following structures would most specifi-

cally explain the loss of pain and thermal sensations on the man’s

Questions 51 through 53 are based on the following patient.

face?

(A) Anterolateral system

A 73-year-old man is brought to the emergency department after los-

(B) Medial lemniscus

ing consciousness at his home. CT shows a hemorrhage into the right

hemisphere. The man regains consciousness, but is not fully alert. Af-

(D) Solitary tract

ter 3-4 days the man begins to rapidly deteriorate: his pupils are large

(E) Spinal trigeminal tract

(dilated) and respond slowly to light, eye movement becomes re-

stricted, there is weakness in the extremities on the left side, and the

man becomes comatose. Repeat CT shows an uncal herniation.

46.

The CT shows an infarcted area in the medulla in this man. Based

on the deficits described, and the corresponding structures in-

volved, which of the following vessels is most likely occluded?

51.

Based on its location, which of the following parts of the brainstem

is most likely to be directly affected by uncal herniation, especially

(A) Anterior spinal artery

in the early stages?

(B) Posterior spinal artery

(A) Diencephalon/thalamus

(D) Anterior inferior cerebellar artery

(B) Mesencephalon/midbrain

(E) Penetrating branches of the vertebral artery

(D) Pons and cerebellum

47.

A 77-year-old man presents with an ataxic gait. There are no other

(E) Pons only

deficits. CT shows an infarcted area in the medulla in the territory

served by the posterior inferior cerebellar artery. Damage to

52.

Damage to corticospinal fibers in which of the following locations

which of the following structures would most likely explain the

would most likely explain the weakness in his extremities?

symptoms experienced by this man?

(A) Left basilar pons

(A) Anterolateral system

(B) Left crus cerebri

(B) Corticospinal tract

(D) Right crus cerebri

(D) Restiform body

(E) Right posterior limb of the internal capsule

(E) Vestibular nuclei

53.

The dilated, and slowly responsive, pupils in this man are most

48.

Which of the following cranial nerve nuclei is located in the ante-

likely explained by damage to fibers in which of the following?

rior (ventral or inferior) and medial portion of the periaqueductal

(A) Abducens nerve

grey at the cross-sectional level of the superior colliculus?

(B) Corticonuclear fibers in the crus

(A) Abducens

(B) Mesencephalic

(D) Optic nerve

(E) Sympathetic fibers on cerebral vessels

(D) Trigeminal motor

(E) Trochlear

54.

The sagittal MRI of a 26-year-old man shows a dark shadow in the

midbrain tegmentum on the midline at the cross-sectional level of

49.

A 53-year-old woman presents with motor deficits that the exam-

the inferior colliculus. Which of the following structures does this

ining neurologist describes as a superior alternating hemiplegia.

dark area represent?

Which of the following cranial nerve roots is most likely involved

(A) Central portions of the red nucleus

in this lesion?

(B) Compact and reticular parts of the substantia nigra

(A) Abducens

(B) Hypoglossal

(D) Decussation of trigeminothalamic fibers

(E) Motor (pyramidal) decussation

(D) Trigeminal

(E) Trochlear

270

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

55.

The CT of a 39-year-old man with untreated hypertension shows

60.

Damage to which of the following tracts or fiber bundles would

a small hemorrhage in the brainstem. This lesion encompasses the

most likely give rise to the sensory deficits experienced by this pa-

brachium of the inferior colliculus and the brain substance imme-

tient?

diately internal to this structure. Which of the following struc-

(A) Anterolateral system

tures is also most likely involved in this lesion?

(B) Medial lemniscus

(A) Anterolateral system

(B) Central tegmental tract

(D) Solitary tract

(E) Spinal trigeminal tract

(D) Mesencephalic tract

(E) Oculomotor nerve

61.

The MRI of a 12-year-old boy reveals a cavity within the medulla.

Which of the following terms most specifically describes this con-

56.

A 69-year-old man complains of difficulty walking. The examina-

dition?

tion reveals no weakness, but does reveal a loss of discriminative

(A) Brown-Séquard syndrome

touch and vibratory sense on the left lower extremity. MRI shows

(B) Central cord syndrome

a small infarcted area in the midbrain. Which of the following

structures is most likely involved in the infarcted area?

(D) Syringobulbia

(A) Anterolateral system

(E) Syringomyelia

(B) Corticospinal fibers

62.

Which of the following cell groups within the white matter of the

(D) Medial part of the medial lemniscus

cerebellum characteristically appears as a long undulating line,

(E) Rubrospinal fibers

looking somewhat like the principle olivary nucleus in the medulla?

(A) Dentate nucleus

57.

Which of the following nuclei containing visceromotor (autonomic)

(B) Emboliform nucleus

cell bodies is located immediately inferior to the medial vestibular

nucleus, medial to the solitary tract and nucleus, and has axons that

(D) Globose nucleus

exit the brainstem on the glossopharyngeal nerve?

(E) Red nucleus

(A) Dorsal motor nucleus

(B) Edinger-Westphal nucleus

Answers for Chapter 5

(D) Intermediolateral cell column

(E) Superior salivatory nucleus

Answer D: Although this patient initially presented with com-

plete motor and sensory losses, some function had returned by 36

58.

An 81-year-old woman is brought to the emergency department

hours; in this case the lesion is classified as an incomplete lesion of

by her adult grandson. He explains that during dinner she slumped

the spinal cord. Patients with no return of function at 24

hours

off of her chair, did not lose consciousness, but had trouble speak-

and no sacral sparing have suffered a lesion classified as complete

ing. The examination reveals weakness of the upper and lower ex-

and it is unlikely that they will recover useful neurologic function.

tremities on the left and deviation of the tongue to the right on

In a central cord and a large syringomyelia there is sparing of pos-

protrusion. Which of the following most specifically describes this

terior column sensations and in a hemisection the loss of motor

deficit in this elderly patient?

function is unilateral. (p. 94-95)

(A) Alternating hemianesthesia

(B) Hemihypesthesia

Answer B: A medullary lesion that results in weakness of the

extremities on one side indicates involvement of the corticospinal

(D) Middle alternating hemiplegia

fibers located in the pyramid on the contralateral side; these fibers

(E) Superior alternating hemiplegia

largely cross in the pyramidal (motor) decussation. Rubrospinal

and vestibulospinal fibers influence the activity of spinal motor

Questions 59 and 60 are based on the following patient.

neurons, but isolated lesions of these fibers would not result in a

A 79-year-old woman is brought to the emergency department after a

unilateral weakness of upper and lower extremities. The antero-

fall in her home from which she was unable to get up. The examination

lateral system and the medial lemniscus are sensory tracts. (p.

reveals a deviation of the tongue to the left on protrusion, a pronounced

98-108, 110-111)

weakness of the right upper and lower extremities, and a loss of posi-

tion and vibratory sense and discriminative touch on the right side of the

Answer B: The anterior choroidal artery serves the optic tract

body below the neck. CT shows an infarcted area in the medulla.

(homonymous hemianopsia) and the inferior portions of the pos-

terior limb of the internal capsule (weakness of the extremities).

59. Which of the following represents the best localizing sign in this

The ophthalmic artery, via its central retinal branch, serves the

patient?

retina; the anterior cerebral artery serves the lower extremity ar-

eas of the motor and sensory cortices; and distal segments of the

(A) Deviation of the tongue

posterior cerebral artery serve the medial temporal cortex and the

(B) Motor loss on lower extremity

visual cortex. The lateral posterior choroidal artery serves the

choroid plexus in the lateral ventricle and some adjacent struc-

(D) Sensory loss on lower extremity

tures. (p. 21, 25, 29, 35, 158-159)

(E) Sensory loss on upper extremity

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

271

Answer D: The head of the caudate nucleus is located in the lat-

10.

Answer C: Wild flailing movements of the extremities, espe-

eral wall of the anterior horn of the lateral ventricle and receives

cially the upper, are hemiballistic movements (hemiballismus);

its blood supply from the medial striate artery (also called the

these are characteristic of a lesion in the subthalamic nucleus.

artery of Heubner). This vessel also serves much of the anterior

Damage to the cerebellar cortex and nuclei and the lenticular nu-

limb of the internal capsule. The lenticulostriate arteries serve a

cleus will result in motor deficits, but these are usually described

large part of the lenticular nucleus and portions of the surround-

as involving tremor, ataxia, and related motor problems. The ven-

ing internal capsule, and thalamoperforating arteries serve ante-

tral lateral nucleus is a thalamic relay center for motor informa-

rior portions of the dorsal thalamus. The anterior choroidal artery

tion and the ventral posterolateral nucleus is a sensory relay nu-

provides blood supply to inferior portions of the internal capsule,

cleus. Lesions of these nuclei will result in motor

(but not

optic tract, and structures in the medial portions of the temporal

hemiballismus) and sensory deficits. (p. 146-149, 158)

lobe. The medial posterior choroidal artery serves choroid plexus

in the lateral and third ventricles and adjacent areas of the lateral

11.

Answer A: Fibers conveying pain and thermal sensations cross

midbrain and caudomedial thalamus. (p. 154-158)

the midline in the anterior white commissure. Consequently, a le-

sion of this structure, as in syringomyelia, would result in a bilat-

Answer C: In this patient the weakness of the right lower ex-

eral loss of these sensations, reflecting the levels of the syrinx.

tremity is related to a lesion of lateral corticospinal tract fibers on

Damage to fibers of the anterolateral system results in a loss of

the right side of the spinal cord. The left corticospinal tract serves

these sensations on the contralateral side and the posterior

the left side of the spinal cord and the left lower extremity.

columns convey proprioception, discriminative touch, and vibra-

Rubrospinal, reticulospinal, and vestibulospinal fibers influence

tory sense. The medial longitudinal fasciculus does not contain

the activity of spinal motor neurons; however, the deficits related

fibers conveying sensory input. (p. 90-91, 94)

to corticospinal tract damage (significant weakness) will dominate

over the lack of excitation to flexor or extensor motor neurons in

12.

Answer C: The anterior spinal artery serves the medial portion

the spinal cord via these tracts. (p. 86-88, 94)

of the medulla, an area that encompasses the medial lemniscus, ex-

iting roots of the hypoglossal nerve, and the corticospinal fibers in

the pyramid. The anterolateral system, spinal trigeminal tract, and

Answer C: The loss of pain and thermal sensations beginning at

rubrospinal tract are in the territory of the posterior inferior cere-

the level of the umbilicus (T10 dermatome) on the left side results

bellar artery (commonly called PICA by clinicians). The posterior

from damage to fibers of the anterolateral system at about the T8

spinal artery in the caudal medulla and spinal cord serves the

level on the right. These fibers ascend 1 to 2 levels as they cross

gracile fasciculus. (p. 110-111)

the midline. Damage at the T6 level would result in a loss begin-

ning at the T8 level on the contralateral side and damage at the T10

13.

Answer C: The masticatory muscles receive their motor inner-

level would result in a loss beginning at about the T12 level. (p.

vation via the motor neurons located in the trigeminal motor nu-

88-89, 94)

cleus on the ipsilateral side; this excludes the right trigeminal nu-

cleus. Facial motor neurons innervate the muscles of facial

Answer E: The artery of Adamkiewicz is usually located at the

expression on the ipsilateral side and the hypoglossal nucleus in-

T12-L1 spinal cord levels and is more frequently (about 65% of

nervates the ipsilateral side of the tongue. (p. 120-121, 124)

the time) seen on the left side. The other cord levels listed may

have small spinal medullary arteries but not the large diameter

14.

Answer E: A pineal tumor impinging on the superior colliculus

vessel characteristic of Adamkiewicz. (p. 94)

may result in a paralysis of upward gaze (Parinaud syndrome). The

inferior colliculus is related to the auditory system, trochlear fibers

Answer E: The thalamoperforating arteries serve the more ros-

innervate the ipsilateral superior oblique muscle, and the posterior

tral portions of the dorsal thalamus. These vessels may originate as

commissure contains fibers related to the pupillary light pathway.

a single trunk or as several vessels from the P₁ segment of the pos-

Occlusion of the great cerebral vein may cause serious neurologic

terior cerebral artery. The anterior choroidal artery serves the op-

deficits but not specifically a paralysis of upward gaze. (p. 136)

tic tract, inferior portions of the internal capsule, choroid plexus

in the temporal horn, and structures in the medial region of the

15.

Answer B: Alternating sensory losses accompanied by a motor

temporal lobe. The thalamogeniculate artery supplies blood to the

deficit on the same side as the loss of vibratory sensation are char-

caudal thalamus, the medial striate arteries to the head of the cau-

acteristics of the Brown-Séquard syndrome (also commonly called

date nucleus, and the lateral striate arteries to much of the lentic-

a spinal cord hemisection). The Wallenberg syndrome is seen in

ular nucleus. (p. 25, 158-159)

lesions of the medulla, and the Benedikt, Claude, and Weber syn-

dromes are seen in lesions of the midbrain. In these brainstem syn-

Answer A: The claustrum is the thin layer of grey matter that is

dromes there are usually characteristic cranial nerve and long tract

located between the extreme and external capsules. It is generally

signs and symptoms. (p. 90-91, 94, 110, 136)

regarded as being functionally related to the insular cortex. The

external medullary lamina is found at the interface of the lateral

16.

Answer E: The rubrospinal tract lies immediately anterior

portions of the thalamus with the internal capsule and the lamina

(ventral) to, and partially overlaps with, the lateral corticospinal

terminalis is the thin structure forming the rostral wall of the third

tract. The anterolateral system is in the anterolateral area of the

ventricle. The putamen is located medial to the external capsule

spinal cord and is spatially separated from the lateral corticospinal

and lateral to the globus pallidus and the stria terminalis is a fiber

tract. The gracile fasciculus is in the posterior columns, the me-

bundle in the groove between the body of the caudate nucleus and

dial longitudinal fasciculus is in the ventral funiculus, and the an-

the dorsal thalamus. (p. 144-153, 162)

terior spinocerebellar tract is located on the anterolateral surface

of the spinal cord. (p. 90-91, 94-95, 100)

272

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

17.

Answer D: The ventral posterolateral nucleus of the thalamus

23.

Answer B: Penetrating branches of the posterior spinal artery

receives the pathways (medial lemniscus and anterolateral system)

serve the posterior columns (gracile and cuneate fasciculi) of the

that relay the information lost as a result of the lesion in this

spinal cord at all levels. Branches of the posterior spinal artery also

woman. The ventral posteromedial nucleus relays comparable in-

serve the gracile nucleus, but this structure is in the medulla, not

formation from the face and the medial geniculate nucleus is re-

in the spinal cord. The lateral corticospinal tract and the antero-

lated to the auditory system. Lesions in the subthalamic nucleus

lateral system are served by the arterial vasocorona on the surface

result in hemiballismus. The anterolateral system relays pain and

of the cord and the internal branches of the anterior spinal artery.

thermal sense; this is only part of the sensory deficits experienced

The medial longitudinal fasciculus is in the territory of the ante-

by this woman. (p. 142, 158-159)

rior spinal artery. (p. 95, 111)

18.

Answer A: The anterolateral system is located internal to the

24.

Answer D: The putamen and the caudate nucleus originate from

position of the anterior spinocerebellar tract; damage to this area

the same group of developing neurons, are collectively referred to

of the spinal cord would most likely result in a loss of pain and

as the neostriatum, and appear in the same shade of grey in a T1-

thermal sensations on the contralateral side of the body below the

weighted MRI. In general, the globus pallidus and pulvinar are dis-

lesion. The lateral corticospinal tract is located internal to the pos-

tinctly lighter than the putamen and the dorsomedial nucleus fre-

terior spinocerebellar tract, the anterior white commissure and

quently appears dark in a shade of grey distinctly different from

the anterior corticospinal tract are located in the anterior funicu-

that of the globus pallidus. (p. 151, 153, 155, 162)

lus of the cord, and the cuneate fasciculus is in the posterior col-

umn medial to the posterior horn at upper thoracic and cervical

25.

Answer C: The pars caudalis portion of the spinal trigeminal nu-

levels. (p. 88-91, 95)

cleus is located in the lateral medulla adjacent to the spinal trigem-

inal tract in cross-sectional levels between the obex and the C1

19.

Answer A: Reticulospinal fibers (medial and lateral) and lateral

level of the spinal cord. This portion of the spinal trigeminal nu-

vestibulospinal fibers are found predominately in the anterolateral

cleus is responsible for relaying pain and thermal information orig-

area of the spinal cord; medial vestibulospinal fibers are located in

inating from the face and oral cavity on one side to the ventral pos-

the medial longitudinal fasciculus. In the decerebrate patient, the

teromedial nucleus on the contralateral side. The pars interpolaris

descending influence of rubrospinal fibers on spinal flexor motor

is found at levels between the obex and the rostral end of the hy-

neurons is removed, and descending influence on extensor motor

poglossal nucleus and the pars oralis between the interpolaris and

neurons is predominant. The posterior columns, posterolateral

the principal sensory nucleus. The principal sensory nucleus is in

area of the cord, and the posterolateral tract do not contain

the pons and the mesencephalic nucleus is in the midbrain. (p.

vestibulospinal or reticulospinal fibers. The intermediate zone, a

98-106, 120, 130)

part of the spinal cord grey matter, contains some of the terminals

of these fibers but not the descending tracts in toto. (p. 86, 88, 90,

26.

Answer E: The solitary nucleus receives general visceral affer-

95)

ent (GVA) and special visceral afferent information (SVA, this in-

put is taste) and is located in the region of the medulla served by

20.

Answer C: Weakness of the muscles of the face, particularly

posterior inferior cerebellar artery. All of the other choices are in

when upper and lower portions of the face are involved, indicate

the territory served by the anterior spinal artery. (p. 111)

a lesion of either the facial motor nucleus or the exiting fibers of

the facial nerve; both are located in the lateral pontine tegmentum

27.

Answer E: The tonsil of the cerebellum is located close to the

at caudal levels. The hypoglossal nucleus innervates muscles of the

midline and immediately above the medulla: its position relative to

tongue, the trigeminal nucleus innervates masticatory muscles,

the cerebellum is caudal, medial, and inferior. Tonsillar herniation

and the abducens nucleus innervates the lateral rectus muscle, all

may compress the medulla, and if sudden, may result in death. The

on the ipsilateral side. The arcuate nucleus is a group of cells lo-

other portions of the cerebellum do not herniate. (p. 110, 123)

cated on the surface of the pyramid. (p.106, 116-120, 124)

28.

Answer B: In addition to other signs or symptoms, lesions in lat-

21.

Answer B: The fibers of the anterolateral system are located in

eral areas of the brainstem may also interrupt hypothalamospinal

the lateral portion of the pontine tegmentum anterior (ventral) to

fibers descending from the hypothalamus to the intermediolateral

the facial motor nucleus; these fibers convey pain and thermal in-

cell column in upper thoracic levels of the spinal cord. In this case

puts. The spinal trigeminal tract and the anterior trigeminothala-

the patient may present with a Horner syndrome, part of which is

mic tract also convey pain and thermal input but from the ipsilat-

a small (constricted) pupil. In addition, the affected pupil may re-

eral and contralateral sides of the face, respectively. The lateral

act slowly to reduced light. The anterolateral system conveys so-

lemniscus is auditory in function and the medial lemniscus conveys

matosensory input and fibers of the medial longitudinal fasciculus

proprioception, vibratory sense, and discriminative touch. (p.

(originating from the medulla) are primarily descending to spinal

116-120, 124)

cord levels. Reticulospinal and vestibulospinal tracts influence

spinal motor neurons. (p. 124)

22.

Answer B: The dorsomedial nucleus is located medial to the in-

ternal medullary lamina and, through its connections, one if its

29.

Answer C: The pulvinar, geniculate nuclei, ventral posterome-

functions is to participate in arousal of the cerebral cortex. The

dial and posterolateral nuclei, centromedian, and some other ad-

other choices are in (anterior nucleus) or lateral to the internal

jacent nuclei are served by the thalamogeniculate artery. The an-

medullary lamina, or, in the case of the globus pallidus, lateral to

terior and ventral anterior thalamic nuclei receive their blood

the internal capsule. (p. 144-149)

supply from thalamoperforating arteries, the substantia nigra via

branches of P₁ and P₂, and globus pallidus from the lenticulostri-

ate branches of M1. (p. 140-141, 158-159)

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

273

30.

Answer E: The short-term loss of function, frequently involv-

36.

Answer A: The facial colliculus is an elevation in the floor of the

ing a specific part of the body, is characteristic of a transient is-

fourth ventricle located medial to the sulcus limitans and formed

chemic attack (commonly called a TIA). The follow-up MRI

by the underlying abducens nucleus and fibers (internal genu)

shows no lesion because there has been no permanent damage.

originating from the facial nucleus. The vestibular area, indicating

TIAs are caused by a brief period of inadequate perfusion of a lo-

the position of the vestibular nuclei, is lateral to the sulcus limi-

calized region of the nervous system; recovery is usually rapid and

tans and the hypoglossal nucleus is internal to the hypoglossal

complete. However, TIAs, especially if repeated, may be indica-

trigone in the medial floor of the ventricle in the medulla. The

tive of an impending stroke. Hemorrhagic strokes frequently re-

trigeminal and facial nuclei are located in the pontine tegmentum

sult in some type of permanent deficit, and the central cord syn-

and do not border on the ventricular space. (p. 34-36, 114-117)

drome has bilateral deficits. A small embolic stroke would be

visible on the follow-up MRI, and in this patient would have re-

37.

Answer A: In this case the weakness of the upper and lower ex-

sulted in a persistent deficit. Syringobulbia may include long tract

tremities on the right reflects damage to corticospinal fibers on the

signs as well as cranial nerve signs. (p.158)

left side of the basilar pons. A lesion of these fibers on the right side

of the pons would produce a left-sided weakness. Rubrospinal

31.

Answer D: Damage to the gracile fasciculus on the left (at the

fibers are not located in the territory of paramedian branches of

T8 level this is the only part of the posterior columns present) ac-

the basilar artery. Also, lesions of rubrospinal fibers and of the

counts for the loss of vibratory sensation (and discriminative

middle cerebellar peduncle do not cause weakness but may cause

touch). Injury to the gracile fasciculus on the right would result is

other types of motor deficits. (p. 24, 116, 124, 190-191)

this type of deficit on the right side. The level of the cord damage

is caudal to the cuneate fasciculi and the anterolateral system con-

38.

Answer A: The exiting fibers of the abducens nerve (on the left)

veys pain and thermal sensations. (p. 86, 88, 90, 94)

are in the territory of the paramedian branches of the basilar artery

and are laterally adjacent to corticospinal fibers in the basilar pons.

32.

Answer A: The loss of pain and thermal sensations on the right

Diplopia may result from lesions of the oculomotor and trochlear

side of the body correlates with a lesion involving the anterolateral

nerves, but these structures are not in the domain of the parame-

system on the left side of the spinal cord. A lesion of the right an-

dian basilar branches. A lesion of the optic nerve results in blind-

terolateral system would result in a left-sided deficit. The gracile

ness in that eye and damage to the facial root does not affect eye

and cuneate fasciculi convey discriminative touch, vibratory sen-

movement but may cause a loss of view of the external world if the

sation, and proprioception. The posterior spinocerebellar tract

palpebral fissure is closed due to facial muscle weakness. (p. 24,

conveys similar information, but it is not perceived/recognized as

116, 124)

such (consciously) by the brain. (p. 88, 90, 94)

39.

Answer D: At caudal pontine levels most, if not all, of the me-

33.

Answer E: The substantia nigra contains a large population of

dial lemniscus is located within the territory served by paramedian

melanin-containing cells, is located in the midbrain just internal to

branches of the basilar artery. Penetrating branches of the anterior

the crus cerebri, and the loss of these cells gives rise to the motor

spinal artery serve the hypoglossal nucleus. The other choices are

deficits characteristic of Parkinson disease. The neurotransmitter

generally in the territories of short or long circumferential

associated with these cells is dopamine. The reticular formation is

branches of the basilar artery. (p. 124-125)

in the core of the brainstem and the pontine nuclei are in the basi-

lar pons; neither of these contain cells with melanin. The red nu-

40.

Answer D: Weakness of the extremities accompanied by paralysis

cleus is in the midbrain, but its reddish tone is related to a rich vas-

of the lateral rectus muscle (innervated by the abducens nerve) on the

cular supply, not to cells containing a pigment. (p. 128-133)

contralateral side indicates a lesion in the caudal and medial pons in-

volving the abducens nerve root and corticospinal fibers. This is a

34.

Answer E: The solitary nucleus is located immediately inferior

middle alternating hemiplegia. Inferior alternating hemiplegia speci-

(ventral) to the medial and spinal vestibular nuclei and is the only

fies involvement of the hypoglossal root and the pyramid, and supe-

nucleus in the choices to receive a general visceral afferent (GVA)

rior alternating hemiplegia indicates damage to the oculomotor root

and special visceral afferent (SVA-taste) input. The inferior saliva-

and the crus cerebri. Alternating (or alternate) hemianesthesia and

tory nucleus and the nucleus ambiguus are visceromotor (general

hemihypesthesia are sensory losses. (p. 116, 124)

visceral efferent [GVE] and special visceral efferent [SVE], respec-

tively) and the spinal trigeminal and cochlear nuclei are sensory

41.

Answer B: The prominent elevation formed on the caudal and

(general somatic afferent [GSA] and special somatic afferent [SSA],

medial wall of the third ventricle, at the general level of the pos-

respectively). (p. 104, 106, 174-175)

terior commissure, represents the location of the habenular nu-

cleus. This is an excellent landmark to use in axial MRI when des-

35.

Answer E: The superior salivatory nucleus lies adjacent to the

ignating the separation between the third ventricle (rostral to this

exiting fibers of the facial nerve in a position just lateral to the ab-

point on the midline) and the quadrigeminal cistern (caudal to this

ducens nucleus in caudal levels of the pons. The preganglionic ax-

point). The pulvinar is lateral to the quadrigeminal cistern, the

ons originating from these cells distribute on peripheral branches

lamina terminalis forms the rostral wall of the third ventricle, and

of the facial nerve. The dorsal motor and inferior salivatory nuclei

the massa intermedia bridges the space of the third ventricle.

are in the medulla and associated, respectively, with the vagus and

When present (in about 80% of patients) the Massa intermedia ap-

glossopharyngeal nerves. The Edinger-Westphal nucleus is related

pears as a shadow in T2-weighted MRI bridging the third ventri-

to the oculomotor nucleus and the intermediolateral cell column

cle. The superior colliculus is a mesencephalic structure found in

is located primarily in thoracic levels of the spinal cord. (p.116,

the quadrigeminal cistern. (p. 76, 138-143, 162)

203)

274

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

42.

Answer E: The red nucleus, exiting fibers of the oculomotor

48.

Answer C: The oculomotor nucleus (containing general somatic

nerve, portions of the corticospinal fibers in the crus cerebri, and

efferent [GSE] cell bodies), along with the Edinger-Westphal (con-

a number of other medially located structures are found in the ter-

taining general visceral efferent [GVE] cell bodies) nucleus, is

ritory of the penetrating branches of the basilar bifurcation. The

found in the most anterior and medial portion of the periaqueduc-

paramedian branches of the basilar artery and the corticospinal

tal grey at the superior colliculus level. The trochlear nucleus is

fibers in the pyramid serve the abducens nerve by branches of the

found at a comparable position, but at the cross-sectional level of

anterior spinal artery. The anterolateral system and the medial

the inferior colliculus. The mesencephalic nucleus is found in the

lemniscus are mainly, if not entirely, in the region of the midbrain

lateral area of the periaqueductal grey, and the trigeminal and ab-

served by branches of the quadrigeminal and posterior medial

ducens nuclei are located in the pons. (p. 130-133, 201)

choroidal arteries. (p. 137)

49.

Answer C: A superior alternating (or alternate) hemiplegia is char-

43.

Answer D: The vocalis muscle (this muscle is actually the me-

acterized by a loss of most eye movement (damage to oculomotor

dial portion of the thyroarytenoid muscle) is innervated, via the

nerve fibers) on the ipsilateral side and weakness of the upper and

vagus nerve, by motor neurons located in the nucleus ambiguus.

lower extremities (damage to corticospinal fibers in the crus cerebri)

The gracile nucleus conveys sensory input from the body and the

on the contralateral side. The abducens nerve is the cranial nerve in-

spinal trigeminal nucleus relays sensory input from the face. The

volved in a middle alternating hemiplegia and the hypoglossal is that

hypoglossal nucleus is motor to the tongue and the facial nucleus

nerve involved in an inferior alternating hemiplegia. The trigeminal

is motor to the muscles of facial expression. (p. 100-106, 110)

nerve innervates the muscles of mastication and the trochlear nerve

innervates the superior oblique muscle. (p. 132, 136, 200)

44.

Answer A: Fibers comprising the anterolateral system convey

pain and thermal sensations from the body, excluding the face.

50.

Answer E: Motor neurons in the nucleus ambiguus innervate,

These fibers are located in lateral portions of the medulla adjacent

primarily through the vagus nerve, the muscles of the throat that

to the spinal trigeminal tract; this latter tract relays pain and ther-

move a bolus of food from the oral cavity to the esophagus. The

mal sensations from the face. The gracile and cuneate fasciculi con-

tongue, via the hypoglossal nucleus and nerve, may move food

vey proprioception, discriminative touch, and vibratory sense in

around in the mouth and toward the back of the oral cavity, but

the spinal cord and the medial lemniscus conveys this same infor-

the actual act of swallowing is through the action of pharyngeal and

mation from the medulla to the dorsal thalamus. (p. 100, 102,

laryngeal musculature. The dorsal motor vagal and inferior saliva-

104, 106, 110)

tory nuclei are both visceromotor (autonomic) nuclei, and the me-

dial vestibular nucleus is involved in the regulation of eye move-

45.

Answer E: The loss of pain and thermal sensations on one side

ment and in balance and equilibrium. (p. 100-106, 110)

of the face correlates with damage to the spinal trigeminal tract;

in this case the loss is ipsilateral to the lesion. The anterolateral sys-

51.

Answer B: The uncus is at the rostral and medial aspect of the

tem relays pain and thermal sensations from the contralateral side

parahippocampal gyrus, and, in this position, is directly adjacent to

of the body, the solitary tract conveys visceral sensory input (es-

the anterolateral aspect of the midbrain. The diencephalon is ros-

pecially taste), and the medial lemniscus contains fibers relaying

tral to this point and the medulla, the most caudal part of the brain-

information related to position sense and discriminative touch.

stem, is located in the posterior fossa. Late stages of uncal hernia-

The medial longitudinal fasciculus does not contain sensory fibers.

tion may, but not always, result in damage to the rostral pons; this

(p. 100-108, 110)

is especially so if the patient becomes decerebrate. The cerebellum

is not involved in uncal herniation. (p. 20, 22, 24, 38, 78, 136)

46.

Answer C: The posterior inferior cerebellar artery (commonly

called PICA by clinicians) serves the posterolateral portion of the

52.

Answer D: Uncal herniation compresses the lateral portion of

medulla, which encompasses the anterolateral system, spinal trigem-

the brainstem, eventually resulting in compression of the corti-

inal tract, and nucleus ambiguus. The anterior and medial areas of the

cospinal fibers in the crus cerebri. Weakness on the patient’s left

medulla (containing the pyramid, medial lemniscus, and hypoglossal

side indicates damage to corticospinal fibers in the right crus. In sit-

nucleus/nerve) are served by the anterior spinal artery and the an-

uations of significant shift of the midbrain due to the herniation, the

terolateral area of the medulla (the region of the olivary nuclei) is

contralateral crus may also be damaged resulting in bilateral weak-

served by penetrating branches of the vertebral artery. The posterior

ness. While all other choices contain corticospinal fibers, none of

spinal artery serves the posterior column nuclei in the medulla and

these areas are directly involved in uncal herniation. (p, 136)

the anterior inferior cerebellar artery (commonly called AICA)

serves caudal portions of the pons and cerebellum. (p. 111)

53.

Answer C: The root of the oculomotor nerve conveys GSE

fibers to four of the six major extraocular muscles and GVE

47.

Answer D: The restiform body is a large fiber bundle located in

parasympathetic preganglionic fibers to the ciliary ganglion from

the posterolateral area of the medulla in the region served by pos-

which postganglionic fibers travel to the sphincter muscle of the

terior inferior cerebellar artery (PICA). This structure contains a

iris. Pressure on the oculomotor root, as in uncal herniation, will

variety of cerebellar afferent fibers including those of the posterior

usually compress the smaller diameter, and more superficially lo-

spinocerebellar tract. Damage to the vestibular nuclei will result

cated GVE fibers first. Optic nerve damage results in blindness in

in a tendency to fall to the ipsilateral side but will also produce

that eye, injury to sympathetic fibers to the eye results in con-

diplopia (double vision) and nausea; symptoms not experienced

striction of the pupil, and an abducens root injury results in an in-

by this patient. The anterolateral system is sensory, the nucleus

ability to abduct that eye. A lesion of corticonuclear fibers in the

ambiguus is motor to muscles of the throat (including the vocalis),

crus results primarily in motor deficits related to the facial, hy-

and the corticospinal tract is not in the PICA territory. (p. 104,

poglossal, and accessory nerves. (p. 136, 201, 221)

106, 110-111)

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

275

54.

Answer C: The decussation of the superior cerebellar peduncle

59.

Answer A: The deviation of the tongue to the left on attempted

is a prominent fiber bundle located in the tegmentum of the mid-

protrusion is the best localizing sign in this woman. This is espe-

brain directly on the midline at the level of the inferior colliculus.

cially the case when the deviation of the tongue is seen in concert

This bundle is made up of cerebellar efferent fibers. The red nu-

with the motor and sensory losses described for this patient. This

cleus is located in the midbrain tegmentum, but not on the mid-

clearly indicates a lesion in the medial medulla encompassing the

line. Decussating trigeminothalamic fibers are found in the

corticospinal fibers, medial lemniscus, and exiting fibers on the

medulla and do not form a visible structure on the midline. The

hypoglossal nerve. Motor and sensory losses, without the cranial

motor decussation is a compact bundle on the midline, but it is in

nerve sign, could suggest a lesion at several different levels of the

the medulla, not the midbrain. The main parts of the substantia ni-

neuraxis. (p. 83, 110-111)

gra are in the midbrain, are seen in sagittal MRI, but they are def-

initely not on the midline. (p. 128, 163, 211)

60.

Answer B: All of the sensory deficits seen in this woman reflect

a lesion in the medial lemniscus, which is located in the medial

medulla in the territory of the anterior spinal artery. The antero-

55.

Answer A: The anterolateral system is located just internal to

lateral system and the spinal trigeminal tract convey pain and ther-

the brachium of the inferior colliculus in the lateral portions of the

mal sensations from the body (sans face) and face, respectively.

midbrain tegmentum. This tract conveys pain and thermal sensa-

The solitary tract is made up of the central processes of vis-

tions from the contralateral side of the body excluding the face.

cerosensory fibers and the medial longitudinal fasciculus at this

Corticospinal fibers are located in the crus cerebri, the mesen-

level contains descending fibers that influence spinal motor neu-

cephalic tract at the lateral edge of the periaqueductal (central)

rons. (p. 100-108, 110-111)

grey, and the central tegmental tract is, as its name indicates, in

the central part of the tegmentum. Oculomotor fibers within the

61.

Answer D: Syringobulbia is a cavitation within the medulla. A

midbrain leave the nucleus, arch through the tegmentum, and exit

cavitation in this location may communicate with a cavity in cer-

on the medial surface of the basis pedunculi into the interpedun-

vical levels of the spinal cord (syringomyelia). Hydromyelia refers

cular cistern. (p. 128-131)

to a cavity of the spinal cord that is lined with ependymal cells. The

central cord and Brown-Séquard syndromes are lesions of the

56.

Answer C: Fibers conveying discriminative touch, vibratory

spinal cord that give rise to characteristic motor and sensory

sensations, and proprioception are located in the lateral lemnis-

losses. (p. 110)

cus; those from the contralateral upper extremity are medial while

those from the contralateral lower extremity are lateral. This man

62.

Answer A: The dentate nucleus appears as a long thin undulat-

has difficulty walking due to a lesion of fibers conveying position

ing line within the white matter core of the cerebellar hemisphere.

sense from the lower extremity, not due to a lesion influencing de-

It is frequently described as having the three-dimensional shape of

scending fibers passing to spinal motor neurons. Fibers of the an-

a crumpled bag with its hilus (the opening of the bag) directed ros-

terolateral system convey pain and thermal sensation. Rubrospinal

tromedially. The other cerebellar nuclei (fastigial, globose, em-

and corticospinal are motor in function; however this man has no

boliform) are small clumps of cells, and the red nucleus is found

weakness. (p. 126-132, 178-179)

in the midbrain, not in the cerebellum. (p. 112-115)

57.

Answer C: The inferior salivatory nucleus is located in the ros-

tral medulla, medial to the solitary tract and nuclei and inferior

to the medial vestibular nucleus. Preganglionic axons that orig-

Review and Study Questions for

inate from these cells distribute on branches of the glossopha-

Chapter 6

ryngeal nerve. The dorsal motor nucleus is in the medulla, its ax-

ons travel on the vagus nerve. The superior salivatory nucleus is

The MRI of a 66-year-old man shows a tumor 2.0 cm in diameter

in the caudal pons and is associated with the facial nerve. Cells

located in the lateral wall of the atrium of the lateral ventricle.

of the Edinger-Westphal nucleus are associated with the oculo-

Which of the following structures does this lesion most likely

motor nucleus of the midbrain and the intermediolateral cell

damage?

column is located primarily in thoracic levels of the spinal cord.

(A) Corticonuclear (corticobulbar) fibers

(p. 106, 203)

(B) Corticospinal fibers

58. Answer C: Weakness of the extremities accompanied by

(D) Pulvinar nucleus

paralysis of muscles on the contralateral side of the tongue (seen

(E) Splenium of the corpus callosum

as a deviation of the tongue to that side on protrusion) indicates

a lesion in the medulla involving the corticospinal fibers in the

Which of the following structures is clearly seen in coronal and ax-

pyramid and the exiting hypoglossal roots. This is an inferior al-

ial brain slices, and in many MRIs, in planes extending from the

ternating hemiplegia. Middle alternating hemiplegia refers to a

midline laterally through the basal nuclei?

lesion of the pontine corticospinal fibers and the root of the ab-

(A) Anterior commissure

ducens nerve, and superior alternating hemiplegia specifies

(B) Column of the fornix

damage to the oculomotor root and crus cerebri. Alternating

(alternate) hemianesthesia and hemihypesthesia are sensory

(D) Optic chiasm

losses. (p. 102, 110)

(E) Posterior commissure

276

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

The MRI of a 49-year-old woman with movement and personality

Which of the following nuclei is located within the internal

disorders and with cognitive dysfunction shows a large anterior

medullary lamina and may be visible in an axial MRI in either T1-

horn of the lateral ventricle. The attending physician suspects that

or T2-weighted images?

her disease has resulted in loss of brain tissue in the lateral wall of

(A) Centromedian

the anterior horn. A loss of which of the following structures would

(B) Dorsomedial

result in this portion of the ventricular system being enlarged?

(A) Body of the caudate nucleus

(D) Ventral anterior

(B) Head of the caudate nucleus

(E) Ventral lateral

(D) Pulvinar nucleus (i)

10.

The sagittal MRI of a 23-year-old woman shows a mass in the right

(E) Septum pellucidum and fornix

interventricular foramen (possibly a colloid cyst); the right lateral

ventricle is enlarged. Based on its location, this mass is most likely

The axial MRI of a 54-year-old man shows an arteriovenous mal-

impinging on which of the following structures?

formation located between the thalamus and the lenticular nu-

(A) Anterior nucleus of thalamus

cleus. Which of the following structures is probably most affected

(B) Posterior limb of internal capsule

by this malformation?

(A) Anterior commissure

(D) Head of caudate nucleus

(B) Anterior limb of the internal capsule

(E) Lamina terminalis

(D) Retrolenticular limb of the internal capsule

11.

The sagittal MRI of a 42-year-old woman taken adjacent to the

(E) Posterior limb of the internal capsule

midline shows a round structure immediately rostral to the in-

terpeduncular fossa on the inferior surface of the hemisphere.

In a sagittal MRI, and in a sagittal brain slice, both taken just off

Which of the following most likely represents this elevation?

the midline (2-4 mm), which of the following structures would

(A) Anterior commissure

be clearly evident immediately caudal to the anterior commissure?

(B) Basilar pons

(A) Column of the fornix

(B) Lamina terminalis

(D) Mammillary body

(E) Optic chiasm

(D) Optic chiasm

(E) Precommissural fornix

12.

Which of the following structures is located immediately inferior

to the pulvinar and, in the sagittal plane (MRI or brain section),

The coronal MRI of a 15-year-old boy shows a 2.0 cm-diameter

forms a distinct elevation immediately adjacent to the lateral as-

tumor in the rostral tip of the temporal (inferior) horn of the lat-

pect of the crus cerebri?

eral ventricle. It is possibly arising from the choroid plexus in this

area of the ventricle. In addition to the hippocampus, this tumor

(A) Mammillary nuclei

is most likely impinging on which of the following structures?

(B) Medial geniculate nucleus

(A) Amygdaloid nucleus

(B) Body of the caudate nucleus

(D) Subthalamic nucleus

(E) Uncus

(D) Optic radiations

(E) Putamen

Answers for Chapter 6

Which of the following structures is located immediately internal

to the crus cerebri and appears as a dark shade of grey (hy-

pointense) in a sagittal T1-weighted MRI?

Answer C: The optic radiations are located in the lateral wall of

the atrium of the lateral ventricle, represent projections from the

(A) Brachium of the inferior colliculus

lateral geniculate nucleus to the calcarine cortex, pass through the

(B) Periaqueductal grey

retrolenticular limb of the internal capsule, and are separated from

the ventricular space by a thin layer of fibers called the tapetum.

(D) Red nucleus

The pulvinar and splenium are located rostromedial and medial,

(E) Substantia nigra

respectively, to the atrium. Corticonuclear and corticospinal

An 81-year-old man is brought to the emergency department fol-

fibers are found in the genu, and the posterior limb of the internal

lowing a fall while walking in the park. The examination reveals

capsule within the hemisphere. (p. 76, 77, 138, 162)

mild confusion and memory loss, but no obvious motor or sensory

deficits. MRI shows an old infarct in the territory of the thalamus

Answer A: The anterior commissure is a mediolaterally oriented

served by the thalamoperforating artery. Which of the following

bundle of fibers that crosses the midline and extends laterally, im-

nuclei is most likely involved in this lesion?

mediately inferior to the basal nuclei. In sagittal section, or in a sagit-

tal MRI, this bundle can be followed into planes of the hemisphere

(A) Centromedian

that include the most lateral portions of the thalamus and the lentic-

(B) Medial geniculate

ular nucleus. The column of the fornix and optic chiasm are located

immediately adjacent to the midline. The posterior commissure is

(D) Ventral posterolateral

located at the caudal aspect of the third ventricle and immediately

(E) Ventral posteromedial

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

277

superior to the opening of the cerebral aqueduct. The genu of the

Answer A: The centromedian nucleus is found within the inter-

internal capsule is medial to the lenticular nucleus and rostrolateral

nal medullary lamina in a position just rostral to the pulvinar. The

to the anterior nucleus of the thalamus. (p. 163, 165, 167, 169, 171)

ventral anterior and ventral lateral nuclei are lateral to the inter-

nal medullary lamina, the dorsomedial nucleus is medial to this

Answer B: The head of the caudate nucleus forms a prominent

lamina, and the pulvinar is the large nucleus forming the caudal

bulge in the lateral wall of the anterior horn of the lateral ventri-

part of the dorsal thalamus. (p. 76, 142-143, 162, 164)

cle. In Huntington’s disease, this elevation disappears, and the

wall of the ventricle may become concave laterally; the result be-

10.

Answer A: The interventricular foramen is the space formed

ing an enlarged anterior horn (hydrocephalus ex vacuo). The body

between the column of the fornix (located somewhat rostrome-

of the caudate is located in the lateral wall of the body of the lat-

dially) and the anterior nucleus of the thalamus (located some-

eral ventricle. The lenticular nucleus lies within the hemisphere

what caudolaterally). The anterior nucleus is located internal to

and does not border on any ventricular space. The septum and the

the anterior tubercle of the thalamus. The head of the caudate is

fornix are located in the medial wall of the ventricle, and the pul-

found in the lateral wall of the anterior horn of the lateral ven-

vinar borders on the superior cistern. (p. 75, 76, 152-156, 162)

tricle, and the posterior limb is located in the hemisphere be-

tween the thalamus and the lenticular nucleus. The lamina ter-

Answer E: The posterior limb of the internal capsule is located

minalis extends from the anterior commissure inferiority to the

between the lenticular nucleus, which is lateral, and the thalamus,

upper edge of the optic chiasm. The habenula is a small elevation

which is medial. This large fiber bundle contains thalamocortical

in the caudal and medial wall of the third ventricle. (p. 76, 162,

projections related to motor and sensory function and descending

164)

corticospinal fibers. The anterior limb of the internal capsule is lo-

cated between the head of the caudate and the lenticular nucleus,

11.

Answer D: The mammillary body forms an obvious elevation

and the retrolenticular limb is found caudal to the lenticular nu-

on the inferior aspect of the hemisphere rostral to the interpe-

cleus. The anterior commissure is in the rostroventral portion of

duncular fossa/cistern; this small bulge is clearly evident in MRI.

the hemisphere, and the extreme capsule is immediately internal

The optic chiasm and the basilar pons are both on the inferior as-

to the insular cortex. (p. 162, 164, 166)

pect of the brain at the midline. The former is rostral to the in-

fundibulum (and the mammillary body) and the latter is caudal to

Answer A: The column of the fornix, commonly called the post-

the interpeduncular fossa. The lamina terminalis forms the rostral

commissural fornix, lies caudal to, and against, the anterior com-

end of the third ventricle and the anterior commissure is adjacent

missure as it arches around the interventricular foramen and the an-

to the column of the fornix. (p. 31, 163, 170)

terior tubercle of the thalamus. The precommissural fornix is a

diffuse bundle of fibers rostral to the anterior commissure, and the

12.

Answer B: The medial and lateral geniculate nuclei are located

mammillothalamic tract is located between the mammillary body

inferior to the pulvinar, and form elevations on the surface of the

and the anterior nucleus of the thalamus. The lamina terminalis and

dorsal thalamus; the medial geniculate is adjacent to the lateral

the optic chiasm are inferior to the anterior commissure. (p. 163)

edge of the crus cerebri. The subthalamic nucleus is located inter-

nally, the mammillary nuclei (medial and lateral) are on the infe-

Answer A: The amygdaloid nucleus is in the rostral wall of the

rior aspect of the thalamus, and the uncus is on the medial portion

temporal horn of the lateral ventricle. In this position the amyg-

on the temporal pole. The optic tract lies on the surface of the crus

dala is separated from the rostral tip of the hippocampus (the hip-

cerebri, but it does not form a distinct elevation on the brain sur-

pocampus occupies the medial and inferior wall of the temporal

face inferior to the pulvinar; rather, it has a structural relationship

horn) by a narrow space of the ventricle. The optic radiations are

to the lateral geniculate nucleus. (p. 26, 59, 169)

in the lateral wall of the temporal horn, but are quite caudal to its

rostral tip. The other choices do not have direct structural rela-

tionship to the rostral portions of the temporal horn. (p. 170, 171)

Review and Study Questions for

Answer E: The substantia nigra is located internal to the crus

Chapter 7

cerebri and, in T1-weighted MRI, appears a darker shade of grey

(hypointense) than does the crus. The red nucleus and the peri-

A 15-year-old boy is brought to the emergency department after

aqueductal grey are located in the midbrain, but do not border on

an accident on his father’s farm. The examination reveals weak-

the crus cerebri. The brachium of the inferior colliculus is found

ness of the left lower extremity, but no frank paralysis. There is a

on the lateral surface of the midbrain, and the pretectal area is ad-

loss of pinprick sensation on the right side beginning at the T8 der-

jacent to the cerebral aqueduct at the midbrain-diencephalic junc-

matome (about half way between the nipple and umbilicus), and

tion. (p. 165, 167)

dorsiflexion of the great toe in response to plantar stimulation.

Based on this examination, which of the following represents the

Answer C: The ventral anterior nucleus is located in the rostral

most likely approximate location of this lesion?

portions of the thalamus, is in the territory of the thalamoperfo-

(A) T6 on the left side

rating artery, and projects to large regions of the frontal lobe. An

(B) T6 on the right side

occlusion of the vessels serving this portion of the thalamus may

result in a decreased level of alertness. The other choices are in

(D) T8 on the right side

caudal regions of the thalamus, are not in the territory served by

(E) T10 on the left side

the thalamoperforating artery, and, with the exception of the cen-

tromedian nucleus, do not relate to the cortex of the frontal lobe.

(p. 159, 162, 164)

278

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

A 47-year-old man is transported to the emergency department

Questions 8 through 9 are based on the following patient.

from the site of an automobile collision. The examination reveals

A 62-year-old woman presents with tremor and ataxia on the right side

a paralysis of both lower extremities. Which of the following most

of the body excluding the head, and with a loss of most eye movement

specifically identifies this clinical picture?

on the left; the woman’s eye is rotated slightly down and out at rest.

(A) Alternating hemiplegia

The left pupil is dilated. There are no sensory losses on her face or

(B) Hemiplegia

body.

(D) Quadriplegia

Based on the deficits seen in this woman, which of the following

(E) Paraplegia

represents the most likely location of the causative lesion?

(A) Cerebellum on the left

A 68-year-old woman presents with a complaint of difficulty swal-

(B) Cerebellum on the right

lowing. Which of the following most specifically identifies this

condition in this patient?

(D) Midbrain on the right

(A) Dysarthria

(E) Rostral pons on the right

(B) Dysmetria

The dilated pupil in this woman is most likely a result of which of

(D) Dyspnea

the following?

(E) Dysdiadochokinesia

(A) Intact parasympathetic fibers on the left

A 37-year-old man presents to his family physician with a com-

(B) Intact parasympathetic fibers on the right

plaint of pain on his face. The examination shows that gentle stim-

ulation of the cheek and corner of the mouth precipitates a severe,

(D) Intact sympathetic fibers on the right

sharp, lancinating pain. A consulting neurologist orders an MRI

(E) Interrupted hypothalamospinal fibers on the left

(T2-weighted), which reveals a vascular loop that appears to be

pressing on the trigeminal root proximal to the ganglion. Which

10.

Which of the following nuclei are the primary target of cerebellar

of the following vessels is most likely involved?

efferent fibers that arise in the dentate, emboliform, and globose

nuclei on the left side?

(A) Anterior inferior cerebellar artery

(B) Posterior cerebral artery

(A) Ventral anterior nucleus on the right

(B) Ventral lateral nucleus on the left

(D) Quadrigeminal artery

(E) Superior cerebellar artery

(D) Ventral posterolateral nucleus on the left

(E) Ventral posterolateral nucleus on the right

Which of the following brainstem structures receives input from

the frontal eye field (in the caudal part of the middle frontal gyrus,

11.

A 22-year-old man presents to his family physician with motor

areas 6 and 8) and is regarded as a vertical gaze center?

deficits. The examination reveals that the man has jerky up-down

(A) Abducens nucleus

movements of his upper extremities especially noticeable in his

(B) Edinger-Westphal nucleus

hands when his arms are extended. Which of the following most

specifically designate this abnormal movement?

(D) Paramedian pontine reticular formation (PPRF)

(A) Akinesia

(E) Rostral interstitial nucleus of the medial longitudinal

(B) Asterixis

fasciculus (MLF)

(D) Intention tremor

A newborn girl baby is unable to suckle. The examination reveals that

(E) Resting tremor

muscles around the oral cavity and of the cheek are poorly developed

or absent. A failure in proper development of which of the following

12.

A 59-year-old man is brought to his family physician by his wife.

structures would most likely contribute to this problem for this baby?

He complains of frequent and severe headaches. His wife states

(A) Head mesoderm

that he does not seem to understand what she is saying when she

(B) Pharyngeal arch 1

talks to him. The examination reveals that the man can speak flu-

ently and clearly, can read notes written on paper, can hear noise,

(D) Pharyngeal arch 3

but has great difficulty understanding or interpreting sounds. MRI

(E) Pharyngeal arch 4

shows a tumor in the temporal lobe. This man is most likely suf-

fering from which of the following?

Which of the following neurotransmitters is associated with hy-

(A) Agnosia

pothalamic fibers that project to the cerebellar cortex (hypothala-

(B) Agraphia

mocerebellar fibers)?

(A) Gamma aminobutyric acid

(D) Aphasia

(B) Glutamate

(E) Aphonia

(D) Noradrenalin

(E) Serotonin

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

279

13. A 47-year-old man is brought to the emergency department by lo-

18.

During a busy day in the emergency department, the neurology

cal law enforcement personnel. The man is thin, undernourished,

resident sees three patients with brainstem lesions. The first is an

somnolent, and clearly intoxicated. Other indicators, such as a

83-year-old woman with a lesion in the territory of the midbrain

lack of personal hygiene, suggest that the man’s condition has been

served by the quadrigeminal and lateral posterior choroidal arter-

long-term. When the physician asks the man his name and where

ies. The second is a 68-year-old man with a posterior inferior cere-

he lives the man give a nonsensical response. This man is most

bellar artery (lateral medullary or Wallenberg) syndrome. The

likely suffering from which of the following?

third is a 47-year-old woman with a presumptive glioblastoma

multiforme invading the mid- to lateral portions of the pontine

(A) Broca aphasia

tegmentum and adjacent portions of the middle cerebellar pedun-

(B) Klüver-Bucy syndrome

cle. Which of the following would most likely be seen in all three

patients assuming a thorough neurologic examination?

(D) Munchausen syndrome

(E) Pick disease

(A) Claude syndrome

(B) Contralateral hemiplegia

Questions 14 through 15 are based on the following patient.

(D) Horner syndrome

A 69-year-old man is diagnosed with dysarthria. The history reveals

(E) Medial medullary syndrome

that the man has had this problem for several weeks. MRI shows an in-

farcted area in the brainstem on the right side.

19.

Which of the following structures serves as an important landmark

in the placement of the intentional division of the spinal cord

14.

Damage to which of the following structures would most likely

(myelotomy) in an anterolateral cordotomy?

explain this deficit in this man?

(A) Anterior median sulcus

(A) Cuneate nucleus

(B) Anterolateral sulcus

(B) Nucleus ambiguus

(D) Posterior intermediate sulcus

(D) Spinal trigeminal tract

(E) Posterolateral sulcus

(E) Vestibular nuclei

20.

A 17-year-old boy is brought to the emergency department from

a high school football game. The examination reveals a loss of vi-

15.

Assuming that the infarcted area in the brain of this man is the re-

bratory sensation and discriminative touch on the left lower ex-

sult of a vascular occlusion, which of the following arteries is most

tremity and to the level of the umbilicus. CT shows a vertebral

likely involved?

fracture with bone displacement into the vertebral canal. Which

(A) Anterior inferior cerebellar

of the following indicates the most likely level of damage to the

(B) Labyrinthine

spinal cord in this boy?

(A) T7-8 on the left

(D) Posterior spinal

(B) T10 on the left

(E) Superior cerebellar

(D) T8-9 on the right

16.

Which of the following neurotransmitters is associated with the

(E) T10 on the right

cells in the somatomotor cortex that project to the spinal cord as

corticospinal fibers?

21.

During the neurologic examination of a 52-year-old man, the

(A) Acetylcholine

physician decides to test the gag reflex. Which of the following dif-

(B) Dopamine

ficulties does this man have that would cause the physician to de-

cide to test this particular reflex?

(D) Glutamate

(A) Dysgeusia

(E) Serotonin

(B) Dysmetria

17.

A 77-year-old woman presents with a loss of pain and thermal sen-

(D) Dyspnea

sations on the right side of her face and on the left side of her body.

(E) Gustatory agnosia

Which of the following most specifically describe this deficit in this

woman?

22.

A 57-year-old woman presents with the main complaint of diffi-

(A) Alternating hemianesthesia

culty speaking. The examination reveals that the woman’s tongue

(B) Epidural anesthesia

deviates to the right on attempted protrusion. When she says “Ah”

her soft palate elevates slightly on the left and the uvula deviates

(D) Hemifacial spasm

to the same side. This combination of deficits would most likely

(E) Superior alternating hemiplegia

indicate a small lesion in which of the following?

(A) Crus cerebri on the right

(B) Genu of the internal capsule on the left

(D) Lateral medulla on the right

(E) Medial medulla on the right

280

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

23. A 36 year-old-woman is diagnosed with myasthenia gravis. Which

28. A 45-year-old-man is brought to his family physician by his wife.

of the following deficits are seen first in about one-half of patients

The man’s main complaint is that he feels “ real dizzy” and a little

with this disease and is present in most at some time during its

nauseated. The examination reveals that the man has a disease of

course?

his semicircular canals. While sitting still the man perceives that

his body is actually moving around the room. Which of the fol-

(A) Diplopia

lowing most specifically describes this condition?

(B) Dysmetria

(A) Ataxia

(D) Tremor

(B) Hysterical vertigo

(E) Upper extremity weakness

(D) Objective vertigo

(E) Subjective vertigo

Questions 24 through 26 are based on the following patient.

An 80-year-old woman is brought to the emergency department from

Questions 29 and 30 are based on the following patient.

an assisted care facility. The woman, who is in a wheelchair, complains

of not feeling well, of numbness on her face, and of being hoarse, al-

A 37-year-old-man is brought to the emergency department from the

though she claims not to have a cold. The examination reveals a loss of

site of an automobile collision. He was unrestrained and, as a result,

pain and thermal sensations on the right side of her face and on the left

has extensive injuries to his face and head. CT shows numerous frac-

side of her body. CT shows an infarcted area in the lateral portion of

tures of the facial bones and skull and blood in the rostral areas of the

the medulla.

frontal lobes and in the rostral 3-4 cm of the temporal lobes, bilater-

ally. After several weeks of recovery the man is moved to a long-term

care facility. His behavior is characterized by (1) difficulty recognizing

24.

A lesion of which of the following structures in this woman would

sounds such as music or words; (2) a propensity to place inappropriate

explain the loss of pain and thermal sensations on her body ex-

objects in his mouth; (3) a tendency to eat excessively or to eat non-

cluding the head?

food items such as the leaves on the plant in his room; and (4) a ten-

(A) Anterolateral system on the left

dency to touch his genitalia.

(B) Anterolateral system on the right

(D) Spinal trigeminal nucleus on the left

29.

Which of the following most specifically describes the tendency of

(E) Spinal trigeminal tract on the left

this man to eat excessively?

(A) Aphagia

25.

The hoarseness in this woman is most likely due to which of the

(B) Dysphagia

following?

(D) Hyperorality

(A) Lesion of the facial nucleus

(E) Hyperphagia

(B) Lesion of the hypoglossal nucleus/nerve

(D) Lesion of the spinal trigeminal tract

30.

Based on the totality of this man’s deficits he is most likely suffer-

(E) Lesion of the trigeminal nucleus

ing from which of the following?

(A) Klüver-Bucy syndrome

26.

Assuming this woman suffered a vascular occlusion, which of the

(B) Korsakoff syndrome

following vessels is most likely involved?

(A) Anterior inferior cerebellar artery

(D) Wallenberg syndrome

(B) Anterior spinal artery

(E) Wernicke aphasia

(D) Posterior spinal artery

31.

A 31-year-old woman is examined by an otolaryngologist pur-

(E) Superior cerebellar artery

suant to her complaint of hearing difficulties. The physician places

a tuning fork against the woman’s mastoid bone until she no longer

27.

In the course of a neurologic examination of a 23-year-old man,

perceives sound, then moves the prongs to her external ear where

the physician places her index finger on the midline of the

a faint sound is again heard. This maneuver is best described as:

mandible and taps it with a percussion hammer stimulating the af-

(A) A negative (abnormal) Rinne test

ferent limb of the jaw ( jaw-jerk) reflex. Collateral fibers from

(B) A normal Binet test

which of the following brainstem nuclei enter the trigeminal mo-

tor nucleus to initiate the motor response?

(D) A positive (normal) Rinne test

(A) Hypoglossal

(E) Weber test localizing to the deaf side

(B) Mesencephalic

(D) Spinal trigeminal, pars caudalis

(E) Spinal trigeminal, pars interpolaris

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

281

32.

A 64-year-old man is brought to a rural health clinic by a neigh-

37. A 59-year-old man, who is a family physician, confides in a neu-

bor. The history reveals that the man is a recluse, lives by himself,

rology colleague that he believes he has early stage Parkinson’s dis-

and does not regularly visit a physician. The examination reveals

ease. The neurologic examination reveals a slight resting tremor

that the man has difficulty walking, chorea and dystonia, and is suf-

of the left hand, a slow gait, and a lack of the normal range of fa-

fering dementia. The neighbor believes that the man’s father died

cial expression for this man. Which of the following is the most

from a similar disease. A tentative diagnosis of Huntington’s dis-

likely location of the degenerative changes at this stage of this

ease is made. Absence of which of the following structures in an

physician’s disease?

MRI of this man would be consistent with this diagnosis?

(A) Bilateral substantia nigra

(A) Anterior lobe of cerebellum

(B) Left globus pallidus

(B) Head of the caudate

(D) Right globus pallidus

(D) Substantia nigra

(E) Right substantia nigra

(E) Subthalamic nucleus

38. A 14-year-old boy is brought to the emergency department after

33.

A 23-year-old man is brought to the emergency department from an

an accident on his BMX bicycle. The examination reveals that the

accident at a construction site. CT shows a fracture of the left mas-

boy has severe facial injuries. Craniofacial CT shows fracture of fa-

toid bone with total disruption of the stylomastoid foramen. Which

cial bones and probable crushing of the structures traversing the

of the following deficits would most likely be seen in this man?

superior orbital fissure. Damage to which of the following struc-

tures passing through this fissure would result in diplopia when at-

(A) Alternating hemianesthesia

tempting to look down and in?

(B) Alternating hemiplegia

(A) Abducens nerve

(D) Facial hemiplegia

(B) Oculomotor nerve

(E) Hemifacial spasm

(D) Ophthalmic vein

34.

Cell bodies located in which of the following ganglia of the head

(E) Trochlear nerve

supply postganglionic fibers to the parotid gland?

Questions 39 through 41 are based on the following patient.

(A) Ciliary

(B) Intramural

A 67-year-old man is brought to the emergency department by his

wife. She explains that he fell suddenly, could not get up, and com-

(D) Pterygopalatine

plained of feeling sick. The examination revealed a left-sided weakness

(E) Submandibular

of the upper and lower extremities, a lack of most movement of the

right eye, and a dilated pupil on the right. MRI shows an infarcted area

Questions 35 and 36 are based on the following patient.

in the brainstem.

A 23-year-old man is brought to the emergency department from the

39. The weakness of this man’s extremities is explained by damage to

site of an automobile collision. CT shows fractures of the facial bones

the axons of cell bodies that are located in which of the following

and evidence of bilateral trauma to the temporal lobes (blood in the

regions of the brain?

substance of the brain).

(A) Left somatomotor cortex

35. As this man recovers, which of the following deficits is most likely

(B) Right anterior paracentral gyrus

to be the most obvious in this man?

(D) Right precentral gyrus

(A) A bilateral sensory loss in the lower body

(E) Right somatomotor cortex

(B) A loss of immediate and short-term memory

40. This man’s dilated pupil is due to damage to which of the follow-

(D) Dementia

ing fiber populations?

(E) Dysphagia and dysarthria

(A) Preganglionic fibers from the Edinger-Westphal nu-

36. Assuming that this man has also sustained bilateral injury to the

cleus

Meyer-Archambault loop, which of the following deficits would

(B) Preganglionic fibers from the inferior salivatory nucleus

this man also most likely have?

(D) Postganglionic fibers from the geniculate ganglion

(A) Bitemporal hemianopsia

(E) Postganglionic fibers from the superior cervical gan-

(B) Bilateral inferior quadrantanopia

glion

(D) Left superior quadrantanopia

41. Which of the following descriptive phrases best describes the con-

(E) Right superior quadrantanopia

stellation of signs and symptoms seen in the man?

(A) Alternating hemianesthesia

(B) Brown-Séquard syndrome

(D) Middle alternating hemiplegia

(E) Superior alternating hemiplegia

282

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

42.

Which of the following structures contains the cell bodies of ori-

46.

The facial sensory deficits experienced by this woman are ex-

gin for fibers conveying taste information from the anterior two-

plained by a lesion to the axons of cell bodies located in which of

thirds of the tongue?

the following structures?

(A) Ciliary ganglion

(A) Anterior trigeminothalamic fibers on the left

(B) Geniculate ganglion

(B) Left trigeminal ganglion

(D) Superior ganglion of the glossopharyngeal nerve

(D) Right trigeminal ganglion

(E) Trigeminal ganglion

(E) Spinal trigeminal nucleus on the right

43.

During a screening neurologic examination of a 39-year-old man,

47.

The loss of pain and thermal sensations experienced by this woman

the physician taps the supraorbital ridge, stimulating the supraor-

on the right side of her body (excluding the face) is most likely the

bital nerve, and elicits a motor response. Which of the following

result of damage to which of the following structures?

most likely represents the motor response in this man?

(A) Anterolateral system fibers on the left

(A) Constriction of the masticatory muscles

(B) Anterolateral system fibers on the right

(B) Constriction of the orbicularis oculi muscle

(D) Medial lemniscus on the left

(D) Dilation of the pupil

(E) Medial lemniscus on the right

(E) Horizontal nystagmus

48.

Taking into account all the deficits experienced by this woman,

44.

A 67-year-old man has a bilateral anterolateral cordotomy at T10

which of the following characterizes the syndrome, and the side,

for intractable pelvic pain. Four months after this procedure the

in this patient?

man begins to experience pain sensations. Which of the following

(A) Benedikt syndrome on the left

would most likely explain this apparent recurrence of pain in this

(B) Lateral medullary syndrome on the left

man?

(A) Activation of postsynaptic posterior column and spin-

(D) Parinaud syndrome (bilateral)

ocervicothalamic pathways

(E) Weber syndrome on the right

(B) Activation of recurrent corticospinal fibers

49.

A 17-year-old boy from a poor rural community is diagnosed with

cortical pathways

hepatolenticular degeneration (Wilson’s disease). Which of the

(D) Regeneration of anterolateral system fibers in the spinal

following is accumulating in certain tissues of his body and pro-

cord

ducing health problems?

(E) Regeneration of anterolateral system fibers into the

(A) Arsenic

posterior column system

(B) Copper

45.

An 84-year-old woman presents to her physician with the com-

(D) Magnesium

plaint of difficulty walking. The examination reveals that the

(E) Mercury

woman has an unsteady gait and tends to forcibly slap her feet to

the floor as she walks. She has no other deficits. The physician con-

50.

Which of the following represents the location of the postgan-

cludes that the woman has sensory ataxia. Degenerative changes

glionic fibers that influence the dilator pupillae muscle of the iris

in which of the following would most likely explain this deficit?

on the ipsilateral side?

(A) Anterolateral system fibers

(A) Ciliary ganglion

(B) Corticospinal fibers

(B) Edinger-Westphal nucleus

(D) Posterior root fibers

(D) Intermediolateral cell column

(E) Vestibulospinal and reticulospinal fibers

(E) Superior cervical ganglion

Questions 46 through 48 are based on the following patient.

51.

A 37-year-old man presents with vertigo, nystagmus, ataxia, and

hearing loss in his right ear. MRI shows a tumor in the cerebello-

A 70-year-old woman is brought to the emergency department by her

pontine angle. A biopsy specimen of this tumor indicates that this

daughter after becoming ill during a trip to the mall. The woman is

mass most likely originated from myelin-forming cells on the root

conscious but lethargic, and she has trouble speaking and swallowing.

of the vestibulocochlear nerve. Which of the following terms most

The examination reveals a loss of pain and thermal sensation on the left

correctly identifies this tumor?

side of the face and a hoarse gravely voice (as if the woman has a sore

throat). Movements of the extremities are normal for the woman’s

(A) Acoustic neuroma

age, but she has a loss of pain and thermal sensations on the right side

(B) Ependymoma

of her body. The corneal reflex is absent on the left side. MRI shows

an infarcted area in the brainstem.

(D) Meningioma

(E) Vestibular schwannoma

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

283

52.

An inherited (autosomal recessive) disorder may appear early in

57. An 11-year-old girl is brought to the family physician by her

the teenage years. These patients have degenerative changes in the

mother. The mother explains that the girl has been complaining

spinocerebellar tracts, posterior columns, corticospinal fibers,

that her hands and arms “feel funny”. In fact, the mother states that

cerebellar cortex, and at select places in the brainstem. The symp-

the girl cut her little finger, but did not realize it until she saw

toms of these patients may include ataxia, paralysis, dysarthria,

blood. The examination reveals a bilateral loss of pain and thermal

and other clinical manifestations. This constellation of deficits is

sensation on the upper extremities and shoulder. Which of the fol-

most characteristically seen in which of the following?

lowing is the most likely cause of this deficit in this girl?

(A) Friedreich ataxia

(A) Brown-Séquard syndrome

(B) Huntington disease

(B) Posterior inferior cerebellar artery syndrome

(D) Parkinson disease

(D) Syringobulbia

(E) Wallenberg syndrome

(E) Syringomyelia

53.

A 45-year-old man complains to his family physician that there seems

58. A 57-year-old obese man is brought to the emergency department

to be something wrong with his mouth. The examination reveals a

by his wife. The examination reveals that cranial nerve function is

weakness of the masticatory muscles, a deviation of the jaw to the left

normal but the man has bilateral weakness of his lower extremities.

on closure, and a sensory loss on the same side of the lower jaw. MRI

He has no sensory deficits. MRI shows a small infarcted area in the

shows a tumor, presumably a trigeminal schwannoma, in the fora-

general region of the cervical spinal cord-medulla junction. Which

men ovale. Compression of which of the following structures would

of the following represents the most likely location of this lesion?

most likely be the cause of the deficits experienced by this man?

(A) Caudal part of the pyramidal decussation

(A) Maxillary and mandibular nerves and motor fibers on

(B) Lateral corticospinal tract on the left

the left

(B) Motor fibers and mandibular nerve on the left

(D) Pyramid on the right

(E) Rostral part of the pyramidal decussation

(D) Motor fibers and maxillary nerve on the left

(E) Motor fibers and maxillary nerve on the right

Questions 59 through 61 are based on the following patient.

A 34-year-old woman presents with the complaint of seeing “two of

54.

A 49-year-old man visits his ophthalmologist with what the man

everything” (diplopia). The history reveals that the woman becomes

interprets as “trouble seeing”. The history reveals that the man had

tired during the workday to the point where she frequently must leave

a sudden event a few days before in which he felt sick and was nau-

her workplace early. The woman said that her vision problems ap-

seated. The man said his trouble “seeing” started after this sudden

peared first, and later she noticed that, when she drank, it would “go

sickness. The examination reveals a loss of abduction and adduc-

down the wrong pipe”. The examination reveals weakness of the ocu-

tion of the right eye and a loss of adduction of the left eye. MRI

lar muscle, difficulty in swallowing (dysphagia), and mild weakness of

confirms an infarcted area in the caudal and medial pontine

the upper extremities. Sensation is normal. Further laboratory tests

tegmentum. Which of the following most specifically identifies

indicate that the woman has a neurotransmitter disease.

this man’s clinical problem?

(A) Horizontal gaze palsy

59. Based on the history and symptoms experienced by this woman,

(B) Internuclear ophthalmoplegia

which of the following is the most likely cause of her medical con-

dition?

(D) Parinaud syndrome

(A) Amyotrophic lateral sclerosis

(E) Vertical gaze palsy

(B) Huntington disease

55.

Collaterals of ascending anterior

(ventral) trigeminothalamic

(D) Multiple sclerosis

fibers that contribute to the vomiting reflex would most likely

(E) Parkinson disease

project into which of the following brainstem structures?

(A) Dorsal motor vagal nucleus

60. Which of the following represents the most likely location of the

(B) Facial nucleus

neurotransmitter dysfunction in this woman?

(A) At the termination of corticonuclear fibers

(D) Superior salivatory nucleus

(B) At the termination of corticospinal fibers

(E) Trigeminal motor nucleus

(D) Within the basal nuclei

56.

The topographical arrangement of fibers in the medial lemniscus at

(E) Within the cerebellum

mid-olivary levels is such that the sensory information being con-

veyed by those fibers located most anterior (ventral) in this bundle

61. Which of the following represents the neurotransmitter most

will eventually terminate in which of the following structures?

likely affected in this woman?

(A) Anterior paracentral gyrus

(A) Acetylcholine

(B) Lateral one-third of the postcentral gyrus

(B) Dopamine

(D) Middle one-third of the postcentral gyrus

(D) GABA

(E) Posterior paracentral gyrus

(E) Serotonin

284

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

62.

A 39-year-old woman complains to her family physician that

67.

A 17-year-old boy presents with the major complaint that he is

“sometimes I see two of everything, but not always”. The exami-

having trouble playing baseball on the high school varsity team.

nation reveals that the woman can abduct both eyes and can adduct

The examination reveals a healthy, well-nurtured, athletic boy

her left eye but cannot adduct her right eye. All other eye move-

with normal motor and sensory function. The visual examina-

ment is normal. MRI shows a small lesion suggesting an area of de-

tion reveals a superior right quadrantanopia. MRI shows a small

myelination in the pons. Which of the following represents the

lesion in a position consistent with the visual field loss. Which of

most likely location of this lesion?

the following represents the most likely location of the lesion in

this boy?

(A) Left abducens nucleus

(B) Left medial longitudinal fasciculus

(A) Crossing fibers in the optic chiasm

(B) Lower portions of the optic radiations in the left tem-

(D) Right medial longitudinal fasciculus

poral lobe

(E) Right PPRF

poral lobe

63.

A 20-year-old man is brought to the emergency department from

(D) Upper portions of the optic radiations in the left pari-

the site of a motorcycle accident. The examination reveals multi-

etal lobe

ple head injuries and a broken humerus. Cranial CT shows a basal

(E) Upper portions of the optic radiations in the right pari-

skull fracture extending through the jugular foramen. Assuming

etal lobe

that the nerve or nerves that traverse this opening are damaged,

which of the following deficits would most likely be seen in this

68.

A 68-year-old man is brought to the emergency department by his

man?

daughter. She explains that he unexpectedly began to have sudden

movements of his left “arm”. The examination reveals a slender

(A) Deviation of the tongue to the injured side on protrusion

man with hypertension and with periodic, uncontrollable flailing

(B) Diplopia and ptosis

movements of his left upper extremity suggestive of hemiballis-

mus. Assuming this to result from a vascular occlusion, MRI

(D) Drooping of the face on the ipsilateral side

would most likely show an infarction in which of the following

(E) Loss of the efferent limb of the corneal reflex

structures?

64.

A 17-year-old boy is brought to the pediatrician by his mother. The

(A) Left substantia nigra

examination reveals that the boy has rigidity, athetoid movements

(B) Left subthalamic nucleus

(athetosis), and difficulty speaking. His ophthalmologist reports

that the boy has a greenish-brown ring at the corneoscleral margin.

(D) Right substantia nigra

This boy is most likely suffering from which of the following?

(E) Right subthalamic nucleus

(A) Huntington disease

Questions 69 through 72 are based on the following patient.

(B) Parkinson disease

A 67-year-old man visits his family physician with the complaint that

(D) Sydenham chorea

he is not able to “do things like I used to”. The examination reveals that

(E) Wilson disease

the man is not able to perform rapid alternating movements with his

left upper extremity, and is not able to touch his left index finger to his

65.

A 32-year-old woman complains to her gynecologist that her

nose because of a tremor that worsens as the finger approaches the

breasts are tender and a white fluid issues from her nipples. The

nose. He is able to do these movements on the right. When he walks,

examination reveals that the woman is not pregnant (she had her

he is unsteady with a tendency to fall to the left. He has no sensory

ovaries removed at age 28 resultant to a diagnosis of ovarian can-

deficits.

cer), that a milky substance can be expressed from her nipples, and

that she has a visual field deficit. MRI shows a tumor impinging on

69. Which of the following terms specifically designates the inability

the midline portion of the optic chiasm. Based on the position of

of this man to perform rapid alternating movements?

this tumor which of the following visual deficits would most likely

(A) Dysarthria

be seen in this woman?

(B) Dysdiadochokinesia

(A) Bitemporal hemianopsia

(B) Left homonymous hemianopsia

(D) Intention tremor

(E) Resting tremor

(D) Right homonymous hemianopsia

(E) Right superior quadrantanopia

70. Which of the following terms specifically designates this man’s in-

ability to touch his nose with his index finger?

66.

Which of the following portions of the cerebellum have a close

(A) Dysmetria

structural and functional relationship with the vestibular appara-

(B) Intention tremor

tus and the vestibular nuclei?

(A) Dentate nucleus and interposed nuclei

(D) Resting tremor

(B) Dentate nucleus only

(E) Static tremor

(D) Hemisphere of the posterior lobe

(E) Interposed nuclei and hemisphere of the anterior lobe

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

285

71.

The MRI of this man shows an infarcted area in the brain. Based

76.

A 39-year-old woman presents with sustained and oscillating mus-

on the deficits this man is experiencing, which of the following

cle contractions that have twisted her trunk and extremities into

represents the most likely location of this lesion?

unusual and abnormal postures. This woman is most likely suffer-

ing from which of the following?

(A) Basal nuclei on the left side

(B) Basal nuclei on the right side

(A) Dysarthria

(B) Dysmetria

(D) Cerebellar cortex and nuclei on the right side

(E) Midbrain on the right side

(D) Dyspnea

(E) Dystonia

72.

Assuming this lesion to be the result of the occlusion of an artery,

77.

A 21-year-old man is brought to the emergency department from

which of the following is the most likely candidate?

the scene of an automobile collision. He has a compound fracture

(A) Left anterior inferior cerebellar artery

of the humerus, a fractured tibia, various cuts and bruises, and sig-

(B) Left superior cerebellar artery

nificant facial trauma. Cranial CT shows fractures of the bones of

the face and orbit on the left, and a total collapse of the optic canal

(D) Right anterior inferior cerebellar artery

on that side with probable transection of the optic nerve. Follow-

(E) Right superior cerebellar artery

ing an initial recovery period, which of the following would most

likely be seen during an ophthalmologic examination?

73.

A 61-year-old woman complains to her family physician that the

(A) A loss of both the direct and consensual pupillary re-

muscles of her face sometimes twitch. The examination reveals

sponse when the light is shown in the right eye

that the woman has irregular and intermittent contractions of fa-

(B) A loss of only the consensual pupillary response when

cial muscles; sometimes these are painful. MRI shows an aberrant

the light is shown in the right eye

loop of an artery that appears to be compressing the facial nerve

root. Which of the following is most likely the offending vessel in

sponse when a light is shown in the left eye

this case?

(D) Direct and consensual pupillary responses are intact

(A) Anterior inferior cerebellar artery

when light is shown in the left eye

(B) Anterior spinal artery

(E) Direct and consensual pupillary responses are intact

when light is shown in the right eye

(D) Posterior spinal artery

(E) Superior cerebellar artery

78.

A 27-year-old man presents with athetosis (athetoid movements),

rigidity, and dysarthria. He also has a flapping tremor. The man

74.

An 81-year-old man presents with a loss of pain, thermal sensa-

has an obvious greenish-brown ring at the corneoscleral margin.

tions, discriminative touch, and vibratory sense on the right side

A tentative diagnosis of advanced Wilson disease is made. MRI

of his body excluding his head. CT shows a comparatively small

showing which of the following would provide further, if not con-

infarct representing the territory of one vessel. Based on the posi-

clusive evidence, of this disease?

tions and relationships of the pathways conveying the sensations

(A) Atrophy of gyri of the frontal and temporal lobes

lost in this man, which of the following represents the most likely

(B) Degeneration and cavitation of the putamen

location of this lesion?

(A) Caudal pons

(D) Loss of cells in the substantia nigra

(B) Midbrain

(E) Loss of the caudate nucleus

(D) Rostral medulla

79.

A 77-year-old man complains to his family physician that he is hav-

(E) Upper cervical spinal cord

ing trouble picking up his coffee cup, shaving with a safety razor,

and picking up the checkers when playing with his grandson. The

examination reveals that the man is unable to control the distance,

75.

The MRI of a 70-year-old man shows an infarcted area in the me-

power, or accuracy of a movement as the movement is taking

dial medulla at a mid-olivary level on the left. This correlates

place. He undershoots or overshoots that target. Which of the fol-

with a loss of position sense from the man’s upper right extrem-

lowing most specifically describes this condition?

ity. Which of the following represents the location of the cell

bodies of origin of those fibers damaged in this patient in the

(A) Bradykinesia

medulla?

(B) Dysarthria

(A) Cuneate nucleus on the left

(D) Dysmetria

(B) Cuneate nucleus on the right

(E) Dysphagia

(D) Gracile nucleus on the right

Questions 80 through 82 are based on the following patient.

(E) Posterior root ganglia on the left

A 70-year-old woman is brought to the emergency department by

members of the volunteer fire department of a small town. She pri-

marily complains of weakness. The examination reveals a hemiplegia

involving the left upper and lower extremities, sensory losses (pain,

thermal sensations, and proprioception) on the left side of the body and

286

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

face, and a visual deficit in both eyes. MRI shows an area of infarction

Answers for Chapter 7

consistent with the territory served by the anterior choroidal artery.

Answer A: The combination of weakness on one side (corti-

80.

Which of the following visual deficits is seen in this woman?

cospinal involvement) and a loss of pain sensation on the opposite

(A) Left homonymous hemianopsia

side specifies components of a Brown-Séquard syndrome. The

(B) Left nasal hemianopsia

motor loss is ipsilateral to the damage and the sensory loss is con-

tralateral; second order fibers conveying pain information cross in

(D) Right homonymous hemianopsia

the anterior white commissure ascending one to two spinal seg-

(E) Right superior quadrantanopia

ments in the process. In this patient, the lesion is on the left side

at about the T6 level; this explains the loss of pain sensation on the

81.

Which of the following most specifically identifies the pattern of

right beginning at the T8 dermatome level. Lesions at T8 or T10

sensory deficits experienced by this woman?

would result in a loss of pain sensation beginning, respectively, at

(A) Alternating hemianesthesia

dermatome levels T10 or T12 on the contralateral side. (p.

(B) Hemianesthesia

180-181)

(D) Sensory level

Answer E: The paralysis of both lower extremities is paraplegia.

(E) Superior alternating hemiplegia

Monoplegia specifies paralysis of one extremity, hemiplegia of

both extremities on the same side, and quadriplegia of all four ex-

82.

The weakness of the extremities in this woman is most likely due

tremities. An alternating hemiplegia is the combination of a mo-

to damage to which of the following?

tor cranial nerve deficit on one side and a hemiplegia on the con-

tralateral side; this is a brainstem lesion not a spinal cord lesion.

(A) Corticospinal fibers on the left

(p. 190-193)

(B) Corticospinal fibers on the right

Answer C: While the causes of swallowing difficulties may be

(D) Thalamocortical fibers to motor cortex on the right

central or peripheral (and multiple), this particular problem is

(E) Thalamocortical fibers to sensory cortex on the right

called dysphagia. Dysmetria is an inability to control the distance

or power of a movement and is commonly seen in cerebellar dis-

83.

A 16-year-old boy is brought to the family physician by his

ease. Dysarthria is difficulty in speaking, and dyspnea is a difficulty

mother. The mother explains that her son is having trouble in

in breathing; the latter is usually associated with diseases of the

school even though he is a hard worker and is well behaved. The

lungs or heart. Dysdiadochokinesia, an inability to perform rapid

examination reveals that the boy has a sensorineural hearing loss

alternating movements, is seen most commonly in cerebellar dis-

in his right ear. He has no other deficits. Which of the following

ease. (p. 190, 202)

represents the most likely location of the lesion in this boy?

(A) Auditory cortex

Answer E: One possible cause of trigeminal neuralgia

(tic

(B) Cochlea

douloureux) is compression of the trigeminal root by the superior

cerebellar artery or its main branches; surgical relocation of the

(D) Inferior colliculus

aberrant vessel (neurovascular decompression) relieves the symp-

(E) Middle ear

toms. Hemifacial spasm may be caused by compression of the fa-

cial nerve by the anterior inferior cerebellar artery (commonly

84.

Which of the following laminae of the lateral geniculate nucleus

called AICA). The other choices do not cause trigeminal neuralgia

receive input from the contralateral retina?

and are not a principal cause of cranial nerve dysfunction via root

(A)

1, 2

compression. (p. 41, 184-185)

(B)

1, 3, 5

(C)

1, 4, 6

Answer E: The rostral interstitial nucleus of the medial longitu-

(D)

2, 3, 5

dinal fasciculus receives cortical input from the frontal eye field on

(E)

3, 4, 5, 6

the ipsilateral side and projects to the ipsilateral (heavy) and con-

tralateral (light) oculomotor and trochlear nuclei. This nucleus is

85.

A 12-year-old girl is brought to the pediatrician by her mother

regarded as the vertical gaze center. The paramedian pontine

who explains that the girl has started to “act funny”. The history

reticular formation is the horizontal gaze center. The oculomotor

reveals that the girl was treated for a hemolytic streptococcus in-

and abducens nuclei do not receive direct input from the frontal

fection 4 weeks before the appearance of her symptoms; the

eye field and the Edinger-Westphal is a visceromotor nucleus con-

mother states that the girl has had this problem for 3 weeks. The

taining preganglionic parasympathetic cell bodies. (p. 192-193)

examination reveals a well-nurtured girl with brisk, flowing, and

irregular movements of her face, neck, and upper extremities.

Answer C: The absence of, or the aberrant development of,

This girl is most likely suffering from which of the following?

muscle around the oral cavity and over the cheek (muscles of fa-

(A) Huntington disease

cial expression, innervated by the facial [VII] nerve) indicate a fail-

(B) Parkinson disease

ure of proper differentiation of the second (2^nd) pharyngeal arch.

Arch 2 also gives rise to the stapedius, buccinator, stylohyoid,

(D) Sydenham chorea

platysma, and posterior belly of the digastric. Mesoderm of the

(E) Weber syndrome

head outside of the pharyngeal arches gives rise to the extraocular

muscles and muscles of the tongue. The muscles of mastication

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

287

(plus the tensor tympani, tensor veli palati, mylohyoid, anterior

ing of written or printed words. Aphonia is a loss of the voice fre-

belly of the digastric) arise from arch 1, the stylopharyngeus from

quently due to disease of, or injury to, the larynx. Aphasia is seen

arch 3, and striated muscles of the pharynx, larynx, and upper

in individuals with a lesion in the dominant hemisphere, and is

esophagus from arch 4. (p. 202-203)

manifest as an inability to comprehend the meaning of spoken,

written, or various other types of input. (p. 226-227)

Answer C: Hypothalamocerebellar fibers that project to the

cerebellar nuclei and cortex contain histamine. GABA is found in

13.

Answer C: The Korsakoff syndrome is a constellation of deficits

several neurons that are located in the cerebellar cortex, and in

the include memory loss, confabulation, amnesia, and dementia

Purkinje cells glutamate is found in many pontocerebellar fibers

that is seen in chronic alcoholics; the manifestations are related, in

and in granule cells of the cerebellar cortex; and noradrenalin is

part, to excessive alcohol consumption and malnutrition. Thera-

found in ceruleocerebellar fibers. Serotonin is found in cells of the

peutic doses of thiamine are used to treat this disease. Broca apha-

reticular formation and in some raphe cells that project to the

sia (nonfluent or expressive aphasia) results from lesions in the

cerebellum. (p. 206-207)

dominant hemisphere. The Klüver-Bucy syndrome is related to

bilateral lesions to the amygdaloid complex, and Pick disease is de-

Answer C: The best localizing sign in this patient is the paucity

mentia related to atrophy of the frontal and temporal lobes. Mun-

of eye movement and dilated pupil on the left; this indicates a le-

chausen syndrome is the fabrication or feigning of illness or disease

sion of the midbrain on the left at the level of the exiting oculo-

to gain attention or control. (p. 232-233)

motor fibers. The red nucleus is found at the same level and, more

importantly, immediately lateral to the red nucleus is a compact

14.

Answer B: Cell bodies in the nucleus ambiguus innervate mus-

bundle of cerebellothalamic fibers. The ataxia and tremor are re-

cles of the pharynx and larynx, including what is commonly called

lated primarily to damage to these cerebellar efferent fibers. The

the vocalis muscle. A lesion of this nucleus is one cause of

motor deficit is contralateral to the lesion because the corti-

dysarthria. The solitary tract and nuclei are concerned with vis-

cospinal fibers, through which the deficit is expressed, cross at the

ceral afferent information including taste, and the spinal trigemi-

motor (pyramidal) decussation. Lesions at the other choices

nal tract is made the central processes of primary sensory fibers

would not result in a paucity of eye movement and are, therefore,

conveying general somatic afferent (GSA) information from the

not potential candidates. (p. 132-133, 208-211)

ipsilateral side of the face and oral cavity. Proprioceptive infor-

mation from the ipsilateral upper extremity is transmitted via the

Answer C: The lesion on the exiting oculomotor fibers (on the

cuneate nucleus; the vestibular nuclei are related to balance, equi-

left) damages the preganglionic fibers from the Edinger-Westphal

librium, and control of eye movement. (p. 202-203)

nucleus and removes their influence on the pupil. Consequently,

the intact postganglionic sympathetic fibers from the ipsilateral su-

15.

Answer C: The area of the brainstem that contains the nucleus

perior cervical ganglion predominate, and the pupil dilates.

ambiguus is served by branches of the posterior inferior cerebel-

Choices on the right are on the incorrect side. Damage to hypo-

lar artery (PICA). Occlusion of this vessel usually gives rise to the

thalamospinal fibers would remove sympathetic influence at the

PICA (lateral medullary or Wallenberg) syndrome. The anterior

intermediolateral cell column, and the pupil would constrict

inferior cerebellar artery (AICA) serves the lateral and inferior

(parasympathetic domination). (p. 200-201, 208-211, 220-221)

cerebellar surface and the superior cerebellar artery serves the su-

perior surface and much of the cerebellar nuclei. The labyrinthine

10.

Answer C: Cerebellar efferent fibers exit the cerebellum via the

artery, a branch of AICA, serves the inner ear. The posterior

superior cerebellar peduncle, cross in its decussation, and termi-

spinal artery serves the posterior columns and their nuclei. (p.

nate primarily in the ventral lateral nucleus (VL). Consequently,

110-111, 202-203)

the cerebellar nuclei on the left project to the right VL. The ven-

tral anterior nucleus does not receive significant cerebellar input.

16.

Answer D: Glutamate is found in many efferent fibers of the

While the ventral posterolateral nucleus receives a limited amount

cerebral cortex including those of the corticospinal tract. Conse-

of cerebellar input, its major role is the relay of somatosensory in-

quently, there are many glutaminergic terminals in the spinal

formation to the primary somatosensory cortex

(postcentral

cord. Acetylcholine is found at many central nervous system

gyrus). (p. 210-211)

(CNS) sites and at the neuromuscular junction, and dopamine is

found mainly in cells of the substantia nigra-pars compacta and in

11.

Answer B: The jerking movements of the upper extremity (as-

their nigrostriatal terminals. Gamma aminobutyric acid (GAMA)

terixis) are also called a flapping tremor and are seen in patients

is an inhibitory neurotransmitter and is found in many interneu-

with hepatolenticular degeneration (Wilson disease). Akinesia is

rons in the CNS. Serotonin is found in CNS areas such as the hy-

lack of movement. Resting tremor is seen in patients with disease

pothalamus, basal nuclei, and the raphe nuclei. (p. 190)

of the basal nuclei, such as Parkinson disease, and an intention

tremor is a characteristic of patients with cerebellar lesions. Dys-

17.

Answer A: The loss of sensation on one side of the face and the

tonia is the result of sustained muscle contractions that twist the

opposite side of the body is an alternating hemianesthesia (also

extremities, trunk, and neck into distorted and abnormal pos-

called an alternate hemianesthesia or a crossed hemianesthesia).

tures. (p. 214-215)

Epidural anesthesia refers to anesthesia resultant to injection of an

appropriate agent into the epidural space. The other choices are

12.

Answer A: This man is unable to recognize or comprehend the

motor abnormalities. (p. 180-181, 186-187)

meaning of sounds; although he is able to hear sounds, he is not

able to put meaning to the sounds; this man is suffering from au-

18.

Answer D: Lesions in the lateral portions of the brainstem dam-

ditory agnosia. Agraphia is the inability to write in a person with

age descending projections from the hypothalamus to the ipsilat-

no paralysis, and alexia is the inability to comprehend the mean-

eral intermediolateral cell column at spinal levels T1-T4, these be-

288

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

ing the hypothalamospinal fibers. The result is Horner syndrome

with this disease. Weakness of the extremities may be seen, but

on the side ipsilateral to the lesion. Horner syndrome may also be

this almost always follows ocular movement disorders. Dysmetria

seen following cervical spinal cord lesions. A contralateral hemi-

is most commonly seen in cerebellar disease and may be present

plegia is not seen in lesions in lateral areas of the brainstem. The

in patients with lesions involving corticospinal fibers. Tremor is

other choices are syndromes or deficits specific to medial brain-

commonly seen in diseases or lesions of the basal nuclei and the

stem areas or to only a particular level. (p. 110, 124, 136,

cerebellum. (p. 200-201)

220-221)

24.

Answer B: The lesion in this woman is in the medulla, and the

19.

Answer C: The denticulate ligament is located on the lateral as-

sensory loss on the body (excluding the head) is on her left side; a

pect of the spinal cord at a midpoint in the posterior-anterior ex-

lesion in the medulla on the right side, involving fibers of the an-

tent of the spinal cord. The anterolateral system, the tract divided

terolateral system (ALS), accounts for this sensory deficit. A le-

in the anterolateral cordotomy, is located in the anterolateral por-

sion of the ALS on the left side of the medulla would result in sen-

tion of the spinal cord just inferior to the position of the denticu-

sory deficits on the right side of the body. The spinal trigeminal

late ligament. The posterolateral sulcus is the entrance point for

tract and nucleus convey pain and thermal sensations from the ip-

sensory fibers of the posterior roots; the anterolateral sulcus is the

silateral side (right side in this case) of the face, and the medial

exit point for motor fibers of the anterior root; and the posterior

lemniscus conveys vibratory and discriminative touch sensations

intermediate sulcus separates the gracile and cuneate fasciculi. The

from the contralateral side of the body. (p. 180-181, 184-185)

anterior median sulcus is located on the anterior midline and con-

tains the anterior spinal artery.

(p. 182-183)

25.

Answer C: The woman is hoarse because the lesion involves the

region of the medulla that includes the nucleus ambiguus. These

20.

Answer B: Damage to the gracile fasciculus on the left at T10,

motor neurons serve, via the glossopharyngeal (IX) and vagus (X)

the level of the umbilicus, will result in the deficits experienced by

nerves, the muscles of the larynx and pharynx, including the me-

this boy. The gracile fasciculus contains uncrossed ascending fibers

dial portion of the thyroarytenoid, also called the vocalis muscle.

conveying vibratory sensation, discriminative touch, and proprio-

Paralysis of the vocalis on one side will cause hoarseness of the

ception; consequently, the deficits will be seen beginning at the

voice. Hypoglossal nucleus or nerve, or facial nucleus lesions may

level of the lesion and extending caudally on the same side. These

cause difficulty with speech but not hoarseness. The spinal trigem-

fibers are the central processes of primary sensory neurons whose

inal tract conveys sensory input from the ipsilateral side of the

cell bodies are located in the ipsilateral posterior root ganglion.

face. There are no historical or examination findings to support a

The other choices are either on the wrong side (right) or at the

diagnosis of upper respiratory viral findings (cold or flu). (p.

wrong level. (p. 178-179)

180-181, 202-203)

21.

Answer C: The gag reflex is not regularly tested. However, in

26.

Answer C: The posterior inferior cerebellar artery

(PICA)

patients with dysphagia (difficulty swallowing) or dysarthria (dif-

serves the lateral area of the medulla that contains the anterolat-

ficulty speaking), the gag reflex should be evaluated. Dysmetria is

eral system, spinal trigeminal tract (loss of pain and thermal sen-

a movement disorder associated with cerebellar lesions; dysgeusia

sations from the ipsilateral side of the face), and the nucleus am-

is the perception of an abnormal taste or of a tastant when there is

biguus. Many patients that present with a PICA (Wallenberg or

none; and dyspnea is difficulty breathing, usually associated with

lateral medullary) syndrome also have involvement of the verte-

disease of the lung or heart. Gustatory agnosia is the inability to

bral artery on that side. The posterior spinal artery serves the pos-

recognize food or distinguish between different food items. (p.

terior column nuclei in the medulla, and the anterior spinal artery

186-187)

serves the pyramid, medial lemniscus, and exiting roots of the hy-

poglossal nerve. The anterior inferior cerebellar artery and the su-

22.

Answer B: The combination of a deviation of the tongue to one

perior cerebellar artery distribute to the pons and midbrain, re-

side (right) and the uvula to the opposite side (left) indicates a le-

spectively, plus significant portions of the cerebellum.

(p.

sion in the genu of the internal capsule on the left involving corti-

110-111, 180)

conuclear (corticobulbar) fibers. Corticonuclear fibers to the hy-

poglossal nucleus are crossed and the tongue deviates toward the

27.

Answer B: The mesencephalic nucleus, a part of the trigeminal

weak side on protrusion. These fibers to the nucleus ambiguus are

complex, has peripheral processes attached to neuromuscular

also crossed resulting in weakness of the contralateral side of the

spindles in the masticatory muscles, unipolar cell bodies in the ros-

palate. However, on attempted phonation (say “Ah”), the strong

tral pons and midbrain, and central collaterals that distribute bi-

side of the palate will contract and elevate, and the uvula will de-

laterally to the trigeminal motor nucleus. Through these connec-

viate to the intact side (opposite to the tongue). Lesions in the

tions, stretching of the spindle initiates a motor response. The

right genu would result in deficits on the opposite sides. Lesions

principal sensory and spinal trigeminal nuclei relay touch and

in the medial medulla on the right would include the tongue, ex-

pain/thermal sensations respectively. The hypoglossal nucleus is

clude the uvula but also show a left-sided hemiplegia. Lesions of

motor to the ipsilateral side of the tongue. (p. 184-185)

the right lateral medulla could include the uvula, but exclude the

tongue. A lesion in the crus would include a number of additional

28.

Answer E: The patient’s perception that his body is moving

deficits and would have to be on the left, not the right. (p.

around the room when he is actually sitting or laying still is sub-

192-193)

jective vertigo. Objective vertigo is the perception, on the part of

the patient, that he is still and objects in the room are moving. As

23.

Answer A: Deficits of eye movement (resulting in diplopia and

its name clearly implies, hysterical vertigo is a psychosomatic dis-

ptosis) are seen first in about 50% of all patients with myasthenia

order. Nystagmus is abnormal rhythmic movements of the eyes,

gravis and are eventually seen in approximately 85% of all patients

usually with fast and slow components. Ataxia is an inability to co-

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

289

ordinate muscle activity resulting in an unsteady gait or other un-

the parotid gland. The ciliary receives from the Edinger-Westphal

coordinated movements. (p. 228-229)

nucleus and sends to the pupil; the pterygopalatine and sub-

mandibular receives from the superior salivatory nucleus (associ-

29.

Answer E: Excessive eating (gluttony), which may include a

ated with the facial [VII] nerve) and send, to the lacrimal, sub-

propensity to attempt to eat things not considered food items, is

mandibular, and sublingual glands, respectively. Intramural

hyperphagia. Dysphagia is difficulty in swallowing, and aphagia is

ganglia are located in the gut and receive input from the dorsal mo-

the inability to eat. Hyperorality is the tendency to put items in

tor vagal nucleus. (p. 202-203)

the mouth or to appear to be examining objects by placing them

in the oral cavity. Dyspnea is difficulty breathing. (p. 234-235)

35.

Answer B: Bilateral damage to the temporal lobes, as in an au-

tomobile collision, may result in damage to the hippocampus.

30.

Answer A: The constellation of deficits experienced by this man

While remote memory, the ability to recall events that happened

is characteristic of the Klüver-Bucy syndrome; this may be seen

years or decades ago, is intact, the man will have difficulty “re-

following bilateral damage to the temporal poles that includes the

membering” recent or immediate events. That is, he will find it

amygdaloid complex. The Korsakoff syndrome is seen, for exam-

difficult, if not impossible, to turn a new experience into longer-

ple, in chronic alcoholics, and senile dementia is a loss of cognitive

term memory (something that can be recalled in its proper con-

and intellectual function associated with neurodegenerative dis-

text at a later time). Dysphagia

(difficulty swallowing) and

eases of the elderly (such as Alzheimer). Wernicke (receptive or

dysarthria (difficulty speaking) are deficits usually seen in brain-

fluent) aphasia is seen in patients with a lesion in the area of the in-

stem lesions. Bilateral sensory losses of the lower portion of the

ferior parietal lobule, and the Wallenberg syndrome results from

body could be seen with bilateral damage to the posterior para-

a lesion in the medulla characterized by alternating hemisensory

central gyri (falcine meningioma) or to the anterior white com-

losses and, depending on the extent of the damage, other deficits.

missure of the spinal cord. Dementia is a multiregional symptom

(p. 234-235)

that usually involves several areas of the brain, cortical as well as

subcortical. (p. 232-233)

31.

Answer D: Hearing a sound in the ipsilateral ear with the appli-

cation of a tuning fork to the mastoid bone (actually the mastoid

36.

Answer C: The Meyer-Archambault loop is composed of optic

process of the temporal bone), and then hearing the sound again at

radiation fibers that loop through the temporal lobe; these fibers,

the external ear by moving the prongs to the external ear after the

on each side, convey visual input from the contralateral superior

sound disappears at the mastoid is a normal Rinne test. In a nega-

quadrant of the visual field. Consequently, a bilateral lesion of

tive Rinne test, the sound is not heard at the external meatus after

these fibers results as a bilateral superior quadrantanopia. Bilateral

it has disappeared from touching the mastoid. In a normal Weber

inferior quadrantanopia is seen in bilateral lesions that would in-

test, sound is heard equally in both ears with application of a tun-

volve the superior portion of the optic radiations. Right or left su-

ing fork to the midline of the forehead. A localizing Weber test in-

perior quadrantanopia is seen in cases of unilateral damage to, re-

dicates that sound is heard in the normal ear, but not in the ear with

spectively, the left or right Meyer-Archambault loop. A

disease or lesion. The Binet is an intelligence test. (p. 226-227)

bitemporal hemianopsia results in a lesion of the optic chiasm. (p.

220, 223)

32.

Answer B: In Huntington disease, especially in advanced stages,

there is a loss of the caudate nucleus and ex vacuo enlargement of

37.

Answer E: Degenerative changes in the dopamine-containing

the ventricles. The most obvious portion of the caudate missing in

cells of the substantia nigra pars compacta on the right side corre-

MRI coronal or axial planes is the head. The anterior lobe of the

late with a left-sided tremor. The altered message through the

cerebellum is diminished in size in alcoholic cerebellar degenera-

lenticular nucleus and thalamus and on to the motor cortex on the

tion, but not so in Huntington disease. Lesions of the subthalamic

side of the degenerative changes will result in tremor on the op-

nucleus result in hemiballismus, and degenerative changes in the

posite (right) side via altered messages traveling down the corti-

substantia nigra result in the motor deficits seen in Parkinson dis-

cospinal tract. The initial symptoms of Parkinson disease appear

ease. One of the main responsibilities of the lateral thalamic nuclei

on one side in about 80% of patients and extend to bilateral in-

is to convey input to the somatomotor and somatosensory cor-

volvement as the disease progresses. Bilateral changes in the sub-

tices. (p. 214-215)

stantia nigra correlate with bilateral deficits. The globus pallidus

does not receive direct nigral input but rather input via a nigro-

33.

Answer D: The paralysis of facial muscles on one side of the face

striatal-striatopallidal circuit. (p. 214-215)

(left in this case) with no paralysis of the extremities is a facial

hemiplegia; this is also commonly known as Bell palsy or facial

38.

Answer E: Damage to the trochlear nerve will cause diplopia on

palsy. Hemifacial spasms are irregular contractions of the facial

gaze inward and downward on the side of the injury. Abducens

muscles, and a central seven refers to paralysis of muscles on the

damage will result in an inability to look laterally on the side of the

lower half of the face contralateral to a lesion in the genu of the in-

lesion, and oculomotor injury will result in the loss of most eye

ternal capsule. Alternating hemiplegia describes a motor loss re-

movement on that side; the eye will be deviated slightly down and

lated to a cranial nerve on one side of the head and motor deficits

out. The ophthalmic nerve is sensory. (p. 200-201)

of the extremities on the contralateral side of the body. A similar

pattern of sensory losses is called an alternating hemianesthesia.

39.

Answer E: The combination of eye movement disorders and a

(p. 202-203)

contralateral hemiplegia localizes this lesion to the midbrain on the

side of the ocular deficits (right side). This also specifies that cor-

34.

Answer C: The otic ganglion receives preganglionic parasympa-

ticospinal fibers on the right (in the crus) are damaged, and places

thetic fibers from the inferior salivatory nucleus (associated with

the location of the cells of origin for these fibers in the somato-

the glossopharyngeal [IX] nerve) and sends postganglionic fibers to

motor cortex on the right side. The right crus contains the axons

290

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

of these fibers but not the neuronal cell bodies. The left somato-

not normally take place in the human nervous system; spinoretic-

motor cortex influences the right extremities. The right precen-

ular fibers are in the divided ALS; and corticospinal fibers function

tral gyrus does not contain cells projecting to the left lumbosacral

in the motor sphere. (p. 182-183)

spinal cord (left lower extremity), and the right anterior paracen-

tral gyrus does not contain the cells that project to the left cervi-

45.

Answer C: The ataxia seen in patients with lesions of posterior

cal spinal cord (left upper extremity). (p. 15, 190-193)

column fibers is due to the loss of proprioceptive input and the re-

sultant inability of the patient to accurately judge the relative po-

40.

Answer A: The lesion in this man is central (brainstem) and in-

sition of the extremity. Thus, the extremity is forcibly slapped to

volves the IIIrd nerve. Consequently, the damage is to the pre-

the floor partially in an attempt to “create” the missing input. An-

ganglionic parasympathetic fibers in the root of the oculomotor

terolateral system fibers convey pain and thermal sensations, and

(III) nerve; this removes the parasympathetic influence (pupil con-

posterior root fibers convey these sensations plus those related to

striction) that originates from the Edinger-Westphal nucleus.

the posterior columns. Corticospinal, vestibulospinal, and reticu-

Fibers from the superior cervical ganglion are intact, hence the di-

lospinal fibers function in the motor sphere. (p. 178-179)

lated pupil. Fibers from the geniculate ganglion and inferior sali-

vatory nucleus distribute on the facial (VII) and glossopharyngeal

46.

Answer B: The axons of cell bodies located in the left trigemi-

(IX) nerves respectively. Postganglionic fibers from the ciliary

nal ganglion collect inside the brainstem to form the spinal trigem-

ganglion, while involved in this pathway, are not damaged in this

inal tract on the left (this tract is made up of the central processes

lesion. (p. 200-201)

of primary sensory fibers on the trigeminal [V] nerve). A lesion of

these fibers on the left side of the medulla will result in a loss of

41.

Answer E: The loss of most eye movement on one side (oculo-

pain and thermal sensations on the left side of the face. Lesions of

motor nerve root involvement) coupled with a paralysis of the ex-

the right trigeminal ganglion, trigeminothalamic fibers on the left,

tremities on the contralateral side is a superior alternating hemi-

and the right spinal trigeminal nucleus would all result in pain and

plegia (this is also Weber syndrome): superior because it is the most

thermal losses on the right side of the face. The principal sensory

rostral of three; alternating because it is a cranial nerve on one side

nucleus conveys touch information. (p. 184-185)

and the extremities on the other; and hemiplegia because one-half

of the body below the head is involved. A middle alternating hemi-

47.

Answer A: Recognizing that this woman has a sensory loss on

plegia involves the abducens (VI) nerve root and adjacent corti-

the left side of her face, damage to fibers of the anterolateral sys-

cospinal fibers, and an inferior alternating hemiplegia involves the

tem on the left correlates with the loss of pain and thermal sensa-

hypoglossal (XII) nerve root and corticospinal fibers in the pyra-

tions on the right side of her body. These anterolateral system

mid. Alternating hemianesthesia is a sensory loss, and a Brown-

(ALS) fibers cross in the spinal cord within about two levels of

Séquard syndrome is a spinal cord lesion with no cranial nerve

where they enter. Lesions of ALS on the right would result in a

deficits. (p. 200-201)

left-sided deficit on the body. Damage to anterior trigeminothal-

amic fibers on the left would produce a corresponding right-sided

42.

Answer B: Taste fibers (special visceral afferent, SVA) that

deficit on the face. The medial lemniscus conveys vibratory, dis-

serve the anterior two-thirds of the tongue on the ipsilateral side

criminative touch, and proprioceptive sensations. (p. 180-181,

are conveyed on the facial nerve and have their cell bodies of ori-

184-185)

gin in the geniculate ganglion. The trigeminal ganglion contains

cell bodies that convey general sensation (general somatic affer-

48.

Answer B: This patient has a lateral medullary syndrome (also

ent, GSA), and the ciliary ganglion contains visceromotor cell

commonly called a posterior inferior cerebellar artery, or PICA

bodies (general visceral efferent GVE, postganglionic, parasym-

syndrome) on the left; this correlates with the left-sided sensory

pathetic). The superior ganglion of the glossopharyngeal contains

loss on the face and right-sided sensory loss on the body. A lateral

cell bodies for taste from the posterior one-third of the tongue,

medullary lesion on the right would result in the same deficits, but

and the superior ganglion of the vagus nerve contains cell bodies

on the opposite sides. The Parinaud, Weber, and Benedikt syn-

for taste from the root of the tongue. (p. 187)

dromes are all associated with lesions in the midbrain.

(p.

180-181, 184-185, see also p. 136)

43.

Answer B: Stimulation of the supraorbital nerve (Vth nerve, af-

ferent limb of the supraorbital reflex) results in contraction of the

49.

Answer B: Wilson disease (hepatolenticular degeneration) is an

orbicularis oculi muscle (VIIth nerve, efferent limb of the supra-

inherited error of copper metabolism. Plasma levels of copper are

orbital reflex). Changes in pupil size relate to the third nerve, the

decreased; urinary levels are increased; and copper accumulates in

pupillary light reflex, and the distribution of postganglionic fibers

the liver, lenticular nuclei, and kidneys. Wilson disease can be

from the superior cervical ganglion. Contraction of masticatory

treated by reducing the level of dietary copper and administering

muscles is seen in the jaw-jerk reflex, and nystagmus usually re-

a copper-chelating agent. Maintenance can be achieved by taking

sults from cerebellum or brainstem lesions or disease of the

zinc, and treatment must be life-long. Ingestion of the other

vestibular apparatus. (p. 184-185, 202-203)

choices can cause serious illness and death. However, none of

these is the causative agent in hepatolenticular degeneration. (p.

44.

Answer A: Fibers in the postsynaptic posterior column and in

214-215)

the spinocervicothalamic pathways are spared in an anterolateral

cordotomy. These pathways originate from those laminae of the

50.

Answer E: The dilator pupillae muscle of the iris is innervated

posterior horn that also contribute to the anterolateral system. It

by postganglionic sympathetic fibers whose cell bodies of origin

is possible that these pathways remodel to transmit pain and ther-

are located in the ipsilateral superior cervical ganglion. Pregan-

mal sensations in the absence of the normal anterolateral system

glionic sympathetic cell bodies are found in the intermediolateral

(ALS) pathway. Regeneration to a functional state probably does

cell column. Preganglionic parasympathetic cell bodies are found

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

291

in the Edinger-Westphal nucleus; axons of these cells terminate in

terminate in the lateral parts of the ventral posterolateral nu-

the ciliary ganglion, which, in turn, innervates the sphincter pupil-

cleus and, from there, be relayed to the posterior paracentral

lae muscle of the iris. The hypothalamus is the origin of hypothal-

gyrus (the lower extremity area of the primary somatomotor

amospinal fibers that project to the intermediolateral cell column.

cortex). The postcentral gyrus is the primary sensory cortex for

(p. 220-21)

the face (approximately the lateral one-third), upper extremity

(middle one-third), and the trunk (medial). The anterior para-

51.

Answer E: The deficits described for the man are consistent

central gyrus is the somatomotor cortex for the lower extrem-

with a tumor on the root of the vestibulocochlear (VIII) nerve;

ity. (p. 179-180)

these are correctly called a vestibular schwannoma because they

arise from the Schwann cells on the root of the vestibular portion

57.

Answer E: Syringomyelia is a cavitation in central areas of the

of the VIIIth nerve. Acoustic neuroma is an earlier, and now in-

spinal cord that results in damage to fibers conveying pain and

correct, designation for this lesion. Meningiomas arise primarily

thermal sensation as they cross the midline in the anterior white

from the arachnoid layer, ependymomas from the cells lining the

commissure. The loss is bilateral since fibers from both sides are

ventricular spaces, and a glioblastoma multiforme arises from as-

damaged as they cross. Tabes dorsalis presents as posterior column

trocytes within the substance of the brain. (p. 228-229)

deficits and lancinating pain; syringobulbia (cavitation within the

brainstem) may have long tract signs and cranial nerve deficits; and

52.

Answer A: This inherited disease is Friedreich ataxia; it initially

PICA syndrome characteristically has alternating sensory losses

appears in children in the age range of 8-15 years and has the char-

(one side of face, opposite side of body). The Brown-Séquard syn-

acteristic deficits described. Huntington disease is inherited, but

drome has both sensory (anterolateral system and posterior col-

appears in adults; olivopontocerebellar atrophy is an autosomal

umn) and motor (corticospinal) deficits. (p. 180-181)

dominant disease and gives rise to a different set of deficits. The

cause of Parkinson disease is unclear, but it is probably not inher-

58.

Answer A: There are basically only two areas where a relatively

ited; the Wallenberg syndrome is a brainstem lesion resulting

restricted lesion would result in weakness of both lower extrem-

from a vascular occlusion. (p. 204-205)

ities. One is in caudal parts of the pyramidal decussation (damage

to decussating corticospinal fibers traveling to the lumbosacral

53.

Answer B: A tumor in the foramen would damage the motor

cord levels), and the other would be a lesion in the falx cerebri

root of the trigeminal nerve and the mandibular root (sensory) of

(such as a meningioma) damaging the lower extremity areas on the

the Vth nerve. In this patient, the jaw deviates to the left and the

somatomotor cortex bilaterally. Decussating fibers in the rostral

sensory loss is on the left; this indicates that the tumor is on the

part of the pyramidal decussation terminate in cervical levels of

left. The deviation of the jaw to the left is due to the action of the

the spinal cord. Damage to either the pyramid or the lateral cor-

intact pterygoid muscles on the right (unlesioned side). Motor

ticospinal tract would result in a hemiplegia (pyramid-contralateral,

fibers on the trigeminal (V) nerve travel in association with the

lateral corticospinal tract-ipsilateral). Damage to the pyramids bi-

mandibular root and through the foramen ovale. Maxillary fibers

laterally would result in quadriplegia. (p. 190-191)

are sensory for the upper jaw and cheek area of the face. (p.

202-203)

59.

Answer C: The fatigability (progressive weakness), involve-

ment of ocular muscles initially, followed by other muscle weak-

54.

Answer C: The loss of abduction and adduction in one eye and

ness, is characteristic of myasthenia gravis. Amyotrophic lateral

of adduction in the opposite eye (the one-and-a-half syndrome) in-

sclerosis is an inherited disease that affects spinal and/or brainstem

dicates a lesion in the area of the paramedian pontine reticular for-

motor neurons and may result in upper or lower motor neuron

mation and abducens nucleus (in this case on the right side) and the

symptoms; this disease is usually fatal within a few years. Multiple

adjacent medial longitudinal fasciculus (MLF). The lesion damages

sclerosis is a demyelinating disease; Parkinson and Huntington dis-

the ipsilateral abducens motor neurons, internuclear neurons

eases are neurodegenerative conditions that eventually have a de-

passing to the contralateral MLF, and internuclear axons in the ip-

mentia component. (p.190, 202)

silateral MLF coming from the contralateral abducens nucleus.

Parinaud syndrome is a paralysis of upward gaze, and gaze palsies

tend to be toward one side and may result from cortical lesions.

60.

Answer C: The history and the combination of signs and symp-

Internuclear ophthalmoplegia is a deficit of medial gaze in one eye,

toms seen in this woman indicate a probable diagnosis of myas-

assuming a one-sided lesion. (p. 192-193)

thenia gravis and, consequently, a neurotransmitter disease at the

neuromuscular junction. Damage to corticospinal and corticonu-

55.

Answer A: Anterior trigeminothalamic collaterals that project

clear terminals and to synaptic contacts within the basal nuclei and

into the dorsal motor nucleus of the vagus are an important link in

the cerebellum would result in motor deficits but not in the pat-

the reflex pathway for vomiting. The superior salivatory nucleus

tern seen in this woman. (p. 190, 202)

is involved in the tearing or lacrimal reflex, the nucleus ambiguus

in the sneezing reflex, and the facial nucleus in the corneal reflex.

61.

Answer A: The neurotransmitter at the neuromuscular junction

Collaterals of primary afferent fibers to the mesencephalic nucleus

is acetylcholine; a blockage of postsynaptic nicotinic acetylcholine

that branch to enter the trigeminal motor nucleus mediate the jaw

receptors is the cause of the motor deficits characteristically seen

reflex. (p. 184-184)

in patients with myasthenia gravis. A loss of dopamine results in

Parkinson disease, motor deficits that are not seen in this woman.

56.

Answer E: The most anterior (ventral) portion of the medial

Glutamate and GABA are found in many pathways involved in mo-

lemniscus at mid-olivary levels contains second order fibers con-

tor function but are not located at the neuromuscular junction.

veying discriminative touch, vibratory sense, and propriocep-

Serotonin is found in pathways related to the basal nuclei, raphe

tion from the contralateral lower extremity. These axons will

nuclei, and the hypothalamus. (p. 190, 202)

292

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

62.

Answer D: A lesion in the medial longitudinal fasciculus (MLF)

diations (geniculocalcarine radiations). The visual loss is in the vi-

on the right interrupts axons of the interneurons that arise from

sual field contralateral to the side of the lesion. Lesions in the

the left abducens nucleus and pass to oculomotor motor neurons

lower portions of the radiations result in deficits in the contralat-

on the right innervating the medial rectus muscle (internuclear

eral superior quadrants, while lesions in the upper portions of the

ophthalmoplegia). Damage to the abducens nucleus will indeed

radiations result in deficits in the contralateral lower quadrants.

destroy these interneurons, but will also result in an inability to

Consequently, in this boy (with a superior right quadrantanopia),

abduct the eye on the ipsilateral side. Injury to the MLF on the left

the lesion is in the lower portions of the optic radiations in the left

would result in an inability to adduct the left eye, and a lesion in

temporal lobe (Meyer-Archambault loop). The lesion in the chi-

the PPRF would most likely produce a bilateral horizontal gaze

asm would result in a bitemporal hemianopsia. (p. 220-223)

palsy. (p. 192-193, 200-201)

68.

Answer E: Hemiballismus is the result of a lesion largely con-

fined to the subthalamic nucleus on the side contralateral to the

63.

Answer C: A fracture through the jugular foramen would po-

deficit. These movements are violent, flinging, unpredictable, and

tentially damage the glossopharyngeal (IX), vagus (X), and spinal

uncontrollable. The abnormal movements are contralateral to the

accessory (XI) nerves. The major observable deficit would be a

lesion because the expression of the lesion is through the corti-

loss of the efferent limb of the gag reflex and a paralysis of the ip-

cospinal tract. Lesions in the left subthalamic nucleus would result

silateral trapezius and sternocleidomastoid muscles (drooping of

in a right-sided problem. Damage in the motor cortex would be

the shoulder, difficulty elevating the shoulder especially against re-

seen as a contralateral weakness, and cell loss in the substantia ni-

sistance, difficulty turning the head to the contralateral side). In-

gra would result in motor deficits characteristic of Parkinson dis-

volvement of facial muscles would suggest damage to the internal

ease (resting tremor, bradykinesia, stooped posture, festinating

acoustic or stylomastoid foramina; this would also be the case for

gait). (p. 216-217)

the efferent limb of the corneal reflex. Diplopia and ptosis would

suggest injury to the superior orbital fissure, as all three nerves

69.

Answer B: The inability to perform a rapid alternating move-

controlling ocular movement traverse this space. The hypoglossal

ment, such as pronating and supinating the hand on the knee, is

nerve (which supplies muscles of the tongue) passes through the

dysdiadochokinesia. This is one of several cardinal signs of cere-

hypoglossal canal. (p. 200-201)

bellar disease or stroke. Dysmetria is an inability to judge power,

distance, and accuracy during a movement, and dysarthria is diffi-

64.

Answer E: The constellation of signs and symptoms experi-

culty speaking. A resting tremor is seen in diseases of the basal nu-

enced by this boy are characteristic of Wilson disease, also called

clei, and an intention tremor is seen in cerebellar lesions. (p.

hepatolenticular degeneration. These may include movement dis-

208-211)

orders, tremor, the Kayser-Fleischer ring at the corneoscleral

margin, and eventual cirrhosis of the liver. Huntington and

70.

Answer B: The tremor that worsens as this man attempts to

Parkinson diseases are predominately motor problems in the early

bring his index finger to his nose is called an intention tremor,

stages and Pick disease is a degenerative disease of the cerebral cor-

sometimes referred to as a kinetic tremor. This type of tremor is

tex affecting mainly the frontal and temporal lobes; dementia is

one cardinal sign of cerebellar lesions. A resting tremor is seen in

the primary deficit. Sydenham chorea is seen in children follow-

diseases of the basal nuclei and a static tremor (postural tremor) is

ing an infection with hemolytic streptococcus; after treatment

seen in the trunk and extremities in a static position. Dysmetria is

for the infection, the choreiform movements usually resolve. (p.

an inability to judge distance, power, or accuracy during a move-

214-215)

ment. The rebound phenomenon is an inability of agonist and an-

tagonist muscles to rapidly adapt to changes in load. (p. 208-211)

65.

Answer A: A tumor impinging on the midline of the optic chi-

asm would damage crossing fibers from both eyes that are coming

71.

Answer C: The signs and symptoms in this man clearly indicate

from the nasal retinae and would reflect a loss of all, or part of both

a lesion in the cerebellum on the left side. The cerebellar nuclei

temporal retinal fields. Between 60% and 70% of pituitary ade-

on the left (lesion side) project to the contralateral thalamus

nomas are prolactin-secreting tumors. Right or left homonymous

(right) and from here to motor cortical areas (also right). The mo-

hemianopsia (the nasal visual field of one eye and the temporal vi-

tor cortex projects, via the corticospinal tract and its decussation,

sual field of the other eye) are seen following lesions of, respec-

back to the side of the body, excluding the head, on which the le-

tively, the left and right optic tracts. Quadrantanopsias result from

sion is located (left cerebellum). The motor expression of the

lesions in the optic radiations. (p. 220-221)

cerebellar deficit is through the corticospinal tract. The man’s left-

sided deficits are not consistent with a right cerebellar lesion, and

66.

Answer C: The flocculonodular lobe and the fastigial nucleus re-

the deficits are not consistent with a midbrain lesion. Lesions of

ceive input from the vestibular apparatus (primary vestibulocere-

the basal nuclei would result in a different set of motor disorders.

bellar fibers) and from the vestibular nuclei (secondary vestibulo-

(p. 208-211)

cerebellar fibers). In turn, the Purkinje cells of the flocculonodular

cortex and cells of the fastigial nucleus project to the vestibular nu-

72.

Answer B: The superior cerebellar artery serves the cortex on

clei as cerebellar corticovestibular and cerebellar efferent fibers,

the superior surface of the cerebellum and most of the cerebellar

respectively. While other areas of the cerebellar cortex may have

nuclei on the same side; in this case, it is the left artery. The ante-

a small projection to the vestibular nuclei, this is not significant

rior inferior cerebellar artery serves the cortex on the lateral infe-

compared to that of the flocculonodular lobe. (p. 228-229)

rior surface of the cerebellum and a small caudal tip of the dentate

nucleus. A lesion that involves primarily the cerebellar cortex will

67.

Answer B: Quadrantanopia, a loss of approximately one quar-

not result in long-term deficits. A lesion that involves cortex plus

ter (a quadrant) of the visual field, is seen in lesions in the optic ra-

nuclei or primarily nuclei, especially in an older patient (as in this

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

293

man), is likely to result in long-term deficits. The lenticulostriate

its head) is seen in Huntington disease. Lacunae are usually seen in

arteries serve the basal nuclei. (p. 208-211)

patients who have had small strokes. (p. 214-215)

73.

Answer A: One cause of hemifacial spasm (intermittent and ab-

79.

Answer D: The inability of this man to control the distance,

normal contractions of the facial muscles) is compression of the fa-

power, and accuracy of a movement is dysmetria; this is charac-

cial root by a loop of the anterior inferior cerebellar artery, or per-

teristically seen in cerebellar lesions. Dysphagia is difficulty swal-

haps one of its larger branches. Aberrant loops of the superior

lowing, and dysarthria is difficulty speaking. The inability to per-

cerebellar artery may compress the trigeminal root (trigeminal neu-

form rapid alternating movements is dysdiadochokinesia, and

ralgia), and the posterior inferior cerebellar artery serves the lateral

bradykinesia is a slowness to initiate movement. The latter is char-

medulla and medial regions of the cerebellum. The anterior and pos-

acteristic of individuals with disease of the basal nuclei.

(p.

terior spinal arteries serve areas of the medulla. (p. 202-203)

208-211)

74.

Answer B: The anterolateral system and the medial lemniscus

80.

Answer A: The territory served by the anterior choroidal artery

are adjacent to each other in lateral portions of the midbrain and

includes the optic tract, inferior portions of the posterior limb of

are served largely by the same vessel(s), these being penetrating

the internal capsule, thalamocortical radiations within the poste-

branches of the quadrigeminal artery. This area may also receive

rior limb, and structures in the temporal lobe. The left-sided

some blood supply from the posterior choroidal arteries.

deficits indicate a lesion on the right side. A lesion of the right op-

Throughout the spinal cord, medulla, and into about the mid- to

tic tract results in a loss of vision in the opposite (left) visual fields;

more rostral pons, these fiber bundles are spatially separated from

this being the temporal visual field of the left eye and the nasal vi-

each other and have separate blood supplies. (p. 137, 178-181)

sual field of the right eye (left homonymous hemianopsia). This

constellation of deficits is known as the anterior choroidal artery

75.

Answer B: Fibers in the left medial lemniscus conveying posi-

syndrome. Quadrantanopia specifies a lesion in a portion of the

tion sense from the right upper extremity originate from cell bod-

optic radiations, and a nasal hemianopsia indicates a small lesion in

ies located in the right cuneate nucleus. These cuneate neurons

the lateral aspect of the optic chiasm on one side. (p. 158-159,

give rise to axons that form the internal arcuate fibers that arch

220-223)

towards the midline, cross, and collect to form the contralateral

medial lemniscus. The left cuneate nucleus sends axons to the

81.

Answer B: This woman has sensory losses on the left side of her

right medial lemniscus, and the gracile nucleus (right or left) con-

body and face that include pain/thermal sensations and the gen-

veys information from the lower extremity. Posterior root ganglia

eral category of proprioception (discriminative touch, vibratory

neurons project to the gracile or cuneate nuclei. (p. 178-179)

and position sense); this is a hemianesthesia, a loss of sensation on

one side of the body. This is a result of damage to thalamocortical

76.

Answer E: Dystonia is a movement disorder characterized by

fibers projecting from the ventral posteromedial and ventral pos-

abnormal, sometimes intermittent, but frequently sustained, con-

terolateral thalamic nuclei to the somatosensory cortex. Alternat-

tractions of the muscles of the trunk and extremities that force the

ing hemianesthesia refers to a sensory loss on one side of the face

body into a twisted posture. Dystonia may be seen in patients with

and on the contralateral side of the body. A sensory level is a char-

diseases of the basal nuclei. Dysmetria is the inability to judge the

acteristic of lesions in the spinal cord, and paresthesia refers to an

distance and trajectory of a movement. Dyspnea is difficulty

abnormal spontaneous sensation not a loss. A superior alternating

breathing; this may result from heart and/or lung disorders as well

hemiplegia is a motor deficit. (p. 158-159, 178-181, 220-223)

as from neurologic disorders. Dysphagia is difficulty swallowing,

and dysarthria is difficulty speaking. (p. 124-215)

82.

Answer B: The corticospinal fibers traversing the inferior por-

tions of the posterior limb of the internal capsule are damaged by

77.

Answer E: Transection of the optic nerve (on the left in this

an occlusion of the anterior choroidal artery; a left-sided deficit

man) eliminates the afferent limb of the pupillary light reflex, but

correlates with a lesion on the right side, especially when taking

the efferent limb, via the oculomotor nerve, is intact. Conse-

into consideration the concurrent visual loss. Damage to corti-

quently, there is a loss of both the direct response (in the blind eye)

cospinal fibers on the left would result in a right-sided deficit. The

and the consensual response (in the good eye) when light is shined

somatomotor cortex is not involved in the lesion. While thalamo-

in the blind eye, because the afferent limb is eliminated and no in-

cortical fibers are certainly damaged in this lesion, the deficits

put is getting to the center from which the efferent limb origi-

related to corticospinal fiber involvement predominate.

(p.

nates. On the other hand, light shined into the good eye (right in

190-191)

this man) results in a direct pupillary response (in the good eye)

and a consensual pupillary response in the blind eye because the

83.

Answer B: Sensorineural hearing loss, also called nerve deaf-

efferent limb of this reflex is not damaged for the blind eye. Other

ness, results from lesions or diseases that involve the cochlea or

combinations of responses may occur as a result of lesions in other

the cochlear portion of the vestibulocochlear nerve. Obstructions

portions of the nervous system. (p. 220-221)

of the external ear or diseases of the middle ear result in conduc-

tive deafness (conductive hearing loss). Lesions in the inferior col-

78.

Answer B: In addition to the motor deficits characteristic of this

liculus, auditory cortex, or other areas within the brain may result

disease, MRI would reveal a spongy degeneration (with cavita-

in difficulty localizing, interpreting, or understanding sound but

tions) of the lenticular nucleus most noticeable in the putamen.

do not result in total deafness in one ear. (p. 226-227)

There may also be a spongy degeneration in areas of the cerebral

cortex. Atrophy of frontal and temporal lobe gyri is seen in Pick

84.

Answer C: Laminae 1, 4, and 6 receive input from the ganglion

disease; loss of nigral cells is characteristic of Parkinson disease;

cells in the contralateral retina. Laminae 2, 3, and 5 receive an ip-

and loss of the caudate nucleus (especially noticeable as absence of

silateral input; laminae 1 and 2 are the magnocellular layers of the

294

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

lateral geniculate nucleus; and laminae 3, 4, 5, and 6 are its par-

The superficial middle cerebral vein forms a direct anastomotic

vocellular layers. (p. 222)

junction with which of the following venous structures on the lat-

eral aspect of the cerebral hemisphere?

85.

Answer D: Sydenham chorea is a disease of childhood thought

(A) Cavernous sinus

to be an autoimmune disorder seen in children as a sequel to a he-

(B) Confluence of sinuses

molytic streptococcus infection. In most children the disease is

self-limiting and the patient recovers with no permanent deficits.

(D) Transverse sinus

Huntington disease, Parkinson disease, and senile chorea present

(E) Veins of Labbé and Trolard

with motor deficits that partially resemble those seen in this girl

but these are diseases of adults or the elderly. Weber syndrome (a

The coronal MRI of a 69-year-old man reveals an infarcted area in

superior alternating hemiplegia) is a motor deficit involving the

the region of the cerebral hemisphere lateral to the internal cap-

oculomotor nerve on one side and the corticospinal tract on the

sule but internal to the insular cortex. A comparison of coronal

opposite side. (p. 214-215)

and sagittal MRI suggests that the vessels involved are branches of

the middle cerebral artery. Which of the following branches or

segments of the middle cerebral artery are most likely involved in

Review and Study Questions for

this man?

Chapter 8

(A) Anterior and polar temporal branches

(B) Insular branches

Which of the following arteries is generally found in the area of the

(D) Opercular segment

cingulate sulcus and has branches that serve the lower extremity

(E) Uncal artery

areas of the somatomotor and somatosensory cortex?

(A) Callosomarginal

The anterior and middle cerebral arteries are the terminal

(B) Frontopolar

branches of which of the following vascular trunks?

(D) Parietooccipital

(A) Basilar artery

(E) Pericallosal

(B) Cavernous part of the internal carotid

A 44-year-old woman presents to her family physician with inter-

(D) External carotid artery

mittent headache and the complaint that she can’t see in her left

(E) Petrous part of the internal carotid

eye. The examination reveals that the woman is blind in her left

eye. When a light is shined into her left eye there is no direct or

The superior sagittal sinus, straight sinus, and transverse sinuses

consensual pupillary light reflex. Magnetic resonance angiography

converge at which of the following landmarks?

(MRA) shows a large aneurysm at the origin of the ophthalmic

(A) Clivus

artery. Which of the following represents the usual point of origin

(B) Confluens sinuum

of this vessel?

(A) Cavernous part of the internal carotid artery

(D) Jugular foramen

(B) Cerebral part of the internal carotid artery

(E) Venous angle

(D) First segment (M1) of the middle cerebral artery

A 47-year-old woman is brought to the emergency department by

(E) Petrous part of the internal carotid artery

her husband. She has a severe headache, nausea, and is somnolent.

The examination reveals that the woman is hypertensive and has

The venous phase of an angiogram of a 52-year-old man suggests

papilledema. MRI shows evidence of cerebral edema, bilateral in-

a small tumor at what the neuroradiologist refers to as the venous

farcted areas in the thalamus, and a large sinus thrombosis that is

angle. Which of the following points most specifically describes

blocking the egress of blood through the vascular system. This

the position of the venous angle?

thrombus is most likely located in which of the following venous

(A) Where the internal cerebral vein meets the great cere-

structures?

bral vein

(A) Inferior sagittal sinus

(B) Where the superficial middle cerebral vein meets the

(B) Left sigmoid sinus

cavernous sinus

(D) Straight sinus

nal cerebral vein

(E) Superior sagittal sinus

(D) Where the transverse sinus turns to form the sigmoid

sinus

(E) Where the vein of Labbé meets the vein of Trolard

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

295

A 39-year-old man presents to his family physician with a com-

14.

A 16-year-old boy with developmental delay has been followed

plaint of difficulty swallowing. The history reveals that the man has

since birth by a pediatric neurologist. A recent MRA is done in

had severe recurring headaches over the last 5 days and suffered

which major arteries and venous sinuses are visualized. It is con-

several bouts of vomiting. The examination confirms the difficulty

cluded that the pattern of the boy’s venous sinuses is essentially

swallowing, and reveals that the man’s voice is hoarse and gravely,

normal. Which of the following describes the usual pattern of the

and that he is unable to elevate his left shoulder against resistance.

superior sagittal sinus at the confluence of sinuses?

MRI shows a dural sinus thrombosis. Based on this man’s deficits,

(A) Always drains equally into the right and left transverse

which of the following represents the most likely location of this

sinuses

thrombus?

(B) Always drains into the left transverse sinus

(A) Left cavernous sinus

(B) Left jugular bulb

(D) Usually drains into the left transverse sinus

(E) Usually drains into the right transverse sinus

(D) Right jugular bulb

(E) Straight sinus

Answers for Chapter 8

10.

Which of the following vessels forms a characteristic loop in the

cisterna magna that is prominent on lateral angiograms and, in the

process, supplies blood to the choroid plexus of the fourth ventri-

Answer A: The callosomarginal artery lies generally in the re-

cle?

gion of the cingulate sulcus and gives rise to branches (paracentral

branches) that distribute to the anterior and posterior paracentral

(A) Anterior inferior cerebellar artery

gyri. The pericallosal artery is located immediately superior to the

(B) Posterior inferior cerebellar artery

corpus callosum and the frontopolar artery serves the medial as-

pect of the frontal lobe. The internal parietal arteries are the ter-

(D) Superior cerebellar artery

minal branches of the pericallosal artery; these vessels distribute

(E) Vertebral artery

to the medial portion of the parietal lobe, the precuneus. The pari-

etooccipital artery is one of the terminal branches (part of P4) of

11.

The MRI of a 42-year-old man shows a small tumor in the choroid

the posterior cerebral artery. (p. 29, 240)

plexus of the third ventricle. Angiogram and MRA suggest that

this tumor contains numerous vascular loops. Which of the fol-

Answer B: In most instances (approximately 80-85%), the

lowing represents the blood supply to this portion of the choroid

ophthalmic artery originates from the cerebral portion of the in-

plexus?

ternal carotid artery just as this parent vessel leaves the cavernous

(A) Anterior choroidal artery

sinus and passes through the dura. In a small percentage of cases

(B) Choroidal branches of AICA

the ophthalmic artery may originate from other locations on the

internal carotid artery, including its cavernous portion. This ves-

(D) Lateral posterior choroidal artery

sel does not originate from the petrous portion of the internal

(E) Medial posterior choroidal artery

carotid or from anterior or middle cerebral arteries. (p. 25, 240)

12.

The angiogram of a 56-year-old woman shows an aneurysm orig-

Answer C: The point at which the thalamostriate vein (also

inating from the lateral aspect of the basilar bifurcation and ex-

called the superior thalamostriate vein at this position) abruptly

tending into the space between the posterior cerebral and superior

turns 180

to form the internal cerebral vein is called the venous

cerebellar arteries. Based on the structure(s) located at this point,

angle. This angle is located immediately caudal to the position of

which of the following deficits would most likely be seen in this

the interventricular foramen and is, therefore, an important land-

woman?

mark. The thalamostriate vein is located in the groove between the

(A) Constriction of the ipsilateral pupil

thalamus and the caudate nucleus. At the superior aspect of the

(B) Inability to look down and out with the ipsilateral eye

thalamus, this vein is the superior thalamostriate vein, and, on the

inferior surface, it is called the inferior thalamostriate vein. None

(D) Inability to look up, down, or medially with the ipsilat-

of the other choices is involved in the formation of the venous an-

eral eye

gle. (p. 241)

(E) Loss of pain and thermal sensation from the ipsilateral

side of the face

Answer E: The superficial middle cerebral vein is a compara-

tively obvious venous structure on the lateral surface of the hemi-

13.

The position of the posterior communicating artery, as frequently

sphere that communicates directly with the veins of Trolard (to

seen in MRA, is an important landmark that specifies the intersec-

the superior sagittal sinus) and Labbé (to the transverse sinus). The

tion of which of the following?

superficial middle cerebral vein also communicates with the cav-

(A) A1 and A2 segments

ernous sinus, but this sinus in not on the lateral aspect of the hemi-

(B) M1and M2 segments

sphere as specified in the question. The other choices do not re-

ceive venous blood directly from the superficial middle cerebral

(D) P1 and P2 segments

vein. (p. 19, 241)

(E) P2 and P3 segments

Answer C: The position of this lesion is in that portion of the

hemisphere occupied by the lenticular nucleus; the lenticulostri-

296

Q & A’s: A Sampling of Study and Review Questions with Explained Answers

ate branches of the M1 segment of the middle cerebral artery serve

may cause certain deficits, but not those experienced by this man.

this structure. The uncal, anterior, and polar temporal branches

(p. 244, 250)

originate from the M1 segment but do not serve structures in the

area of the hemisphere described. Insular branches (M2) and op-

10.

Answer B: The posterior inferior cerebellar artery (commonly

ercular branches (M3) serve cortical structures. (p. 25, 242)

called PICA) originates from the vertebral artery, courses around

the lateral aspect of the medulla, loops sharply into the space of

Answer C: As the internal carotid artery exits the cavernous si-

the cisterna magna (giving off small branches to the choroid plexus

nus, it becomes the cerebral part of the internal carotid and, after

in the fourth ventricle), then joins the inferior and medial surface

giving rise to three important small branches (ophthalmic, ante-

of the cerebellum. None of the other choices forms prominent

rior choroidal, posterior communicating), bifurcates into the an-

vascular structures in the cisterna magna or serves the choroid

terior and middle cerebral arteries. These two cerebral vessels are

plexus of the fourth ventricle. (p. 246)

the terminal branches of the cerebral part of the internal carotid

artery. In approximately 70-75% of specimens, the anterior cere-

11.

Answer E: The medial posterior choroidal artery originates from

bral artery is the smaller of these two terminal branches. None of

the P2 segment of the posterior cerebral artery, arches around the

the other choices gives rise to the anterior and middle cerebral ar-

midbrain, and enters the caudal end of the third ventricle. The an-

teries. (p. 242)

terior choroidal artery serves the choroid plexus in the temporal

horn, and the lateral posterior choroidal artery serves the glomus

Answer B: The superior sagittal sinus, straight sinus, the two

choroideum and extends into the plexi of the temporal horn and

transverse, and the occipital sinus (when present) converge at the

the body of the ventricle. These patterns may be somewhat vari-

confluence of sinuses (confluens sinuum), which is located inter-

able. Choroidal branches of anterior inferior cerebellar artery

nal to the external occipital protuberance. The venous angle is the

(AICA) serve the choroid plexus extending through the foramen of

junction of the thalamostriate and the internal cerebral veins, and

Luschka, and these branches from the posterior inferior cerebellar

the great cerebral vein (of Galen) receives the internal cerebral

artery (PICA) serve the plexus within the fourth ventricle. (p. 251)

veins and several smaller veins including the basal vein (of Rosen-

thal) and empties into the straight sinus. The jugular foramen con-

12.

Answer D: The oculomotor nerve (III) is located between the

tains the transition from the sigmoid sinus to the internal jugular

posterior cerebral and superior cerebellar arteries and may be

vein and the terminus of the inferior petrosal sinus. The clivus is

damaged by aneurysms at this location. Most eye movement

composed mainly of the basal part of the occipital bone; this is the

would be lost (the trochlear (IV) and abducens (VI) nerves are in-

location of the basilar plexus. (p. 19. 23, 243-245)

tact) and the ipsilateral pupil would be dilated, not constricted.

Sensation from the face is carried on the trigeminal nerve. Move-

Answer D: A key observation in this woman is the bilateral in-

ment deficits related to injury to the IVth nerve (looking down and

farcted areas in the thalamus. The straight sinus receives venous

out) or the VIth nerve (looking laterally) are not affected. (p. 39,

flow from both internal cerebral veins; a blockage of flow through

40, 247, 252)

the straight sinus would adversely affect both thalami. Such a le-

sion would also cause potential damage to the medial temporal

13.

Answer D: The posterior communicating artery originates

lobe due to the disruption of flow through the basal vein (of Rosen-

from the cerebral part of the internal carotid artery and courses

thal). None of the other choices receives venous drainage directly

caudally to join the posterior cerebral artery (PCA). The part of

from the thalamus. (p. 29, 248, 250)

the PCA medial to this intersection is the P1 segment and the part

of the PCA immediately lateral to this junction is the P2 segment.

Answer B: The deficits experienced by this man (difficulty swal-

Important branches arise from both of these parts of the PCA.

lowing, hoarseness, inability to elevate the left shoulder against re-

None of the other choices have any direct relationship to the points

sistance) point to damage to the glossopharyngeal (IXth), vagus

of origin of the posterior communicating artery. (p. 25, 247, 249)

(Xth), and spinal accessory (XIth) nerves or to their roots. All

three of these cranial nerves exit the jugular foramen along with

14.

Answer E: The drainage pattern of the superior sagittal sinus at

the continuity of the sigmoid sinus with the internal jugular vein

the confluence of sinuses is variable, including about equal to both

( jugular bulb or bulb of the jugular vein). In this case, the venous

transverse sinuses or mainly to the right or to the left. However,

thrombosis is at the left jugular bulb and impinging on these three

the usual pattern is for the superior sagittal sinus to drain pre-

cranial nerve roots. Dural sinus thrombosis of the other choices

dominately into the right transverse sinus. (p. 245)

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