Clinical Neuroanatomy

562 Pages·2009·42.645 MB·English

by  Richard S. Snell

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C
LINICAL
N
EUROANATOMY
S E V E N T H E D I T I O N
Richard S.Snell,
M.R.C.S., L.R.C.P., MB, BS, MD, PhD
Emeritus Professor of Anatomy
George Washington University
School of Medicine and Health Sciences
Washington,DC
Formerly Associate Professor of Anatomy and Medicine,Yale University Medical
School;Lecturer in Anatomy King’s College University of London;and Visiting
Professor of Anatomy,Harvard Medical School.
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Seventh Edition
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9 8 7 6 5 4 3 2 1
Library of Congress Cataloging-in-Publication Data
Snell,Richard S.
Clinical neuroanatomy / Richard S.Snell.— 7th ed.
p.;cm.
Includes bibliographical references and index.
ISBN 978-0-7817-9427-5
1. Neuroanatomy. I.Title.
[DNLM:1. Nervous System—anatomy & histology.WL 101 S671c 2010]
QM451.S64 2010
616.8—dc22
2008040897
DISCLAIMER
Care has been taken to confirm the accuracy of the information present and to describe gen-
erally accepted practices.However,the authors,editors,and publisher are not responsible for errors
or omissions or for any consequences from application of the information in this book and make no
warranty,expressed or implied,with respect to the currency,completeness,or accuracy of the con-
tents of the publication.Application of this information in a particular situation remains the profes-
sional responsibility of the practitioner;the clinical treatments described and recommended may
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P R E F A C E
T his book contains the basic neuroanatomical facts will encounter when making a diagnosis and treating a
necessary for the practice of medicine. It is suitable patient. It also provides the information necessary to
for medical students, dental students, nurses, and understand many procedures and techniques and notes
allied health students. Residents fnd this book use- the anatomical “pitfalls” commonly encountered.
ful during their rotations. ● Clinical Problem Solving.This section provides the stu-
The functional organization of the nervous system has dent with many examples of clinical situations in which a
been emphasized and indicates how injury and disease can knowledge of neuroanatomy is necessary to solve clinical
result in neurologic deficits. The amount of factual infor- problems and to institute treatment; solutions to the prob-
mation has been strictly limited to that which is clini- lems are provided at the end of the chapter.
cally important. ● Review Questions. The purpose of the questions is
In this edition, the content of each chapter has been threefold: to focus attention on areas of importance, to
reviewed, obsolete material has been discarded, and new enable students to assess their areas of weakness, and to
material added. provide a form of self-evaluation when questions are
Each chapter is divided into the following categories: answered under examination conditions. Some of the
questions are centered around a clinical problem that
requires a neuroanatomical answer. Solutions to the prob-
● Clinical Example. A short case report that serves to
lem are provided at the end of each chapter.
dramatize the relevance of neuroanatomy introduces each
chapter.
In addition to the full textfrom the book, an interactive
● Chapter Objectives.This section details the material that
Review Test, including over 450 questions, is provided
is most important to learn and understand in each chapter.
online.
● Basic Neuroanatomy. This section provides basic infor-
The book is extensively illustrated. The majority of the fig-
mation on neuroanatomical structures that are of clinical
ures have been kept simple and are in color. As in the previ-
importance. Numerous examples of normal radiographs,
ous edition, a concise Color Atlas of the dissected brain is
CT scans, MRIs, and PET scans are also provided. Many
included prior to the text. This small but important group of
cross-sectional diagrams have been included to stimulate
colored plates enables the reader to quickly relate a particu-
students to think in terms of three-dimensional anatomy,
lar part of the brain to the whole organ.
which is so important in the interpretation of CT scans and
References to neuroanatomical literature are included
MRI images.
should readers wish to acquire a deeper knowledge of an
● Clinical Notes. This section provides the practical appli-
area of interest.
cation of neuroanatomical facts that are essential in clini-
cal practice. It emphasizes the structures that the physician R.S.S.
iii
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A C K N O W L E D G M E N T S
I am greatly indebted to the following colleagues who grateful to Dr. G. Size of the Department of Radiology at Yale
provided me with photographic examples of neu- University Medical Center for examples of CT scans and MRI
roanatomical material: Dr. N. Cauna, Emeritus images of the brain. I also thank Dr. H. Dey, Director of the
Professor of Anatomy, University of Pittsburgh School PET Scan Unit of the Department of Radiology, Veterans
of Medicine; Dr. F. M. J. Fitzgerald, Professor of Anatomy, Affairs Medical Center, West Haven, Connecticut, for several
University College, Galway, Ireland; and Dr. A. Peters, examples of PET scans of the brain. I thank the medical pho-
Professor of Anatomy, Boston University School of Medicine. tographers of the Department of Radiology at Yale for their
My special thanks are owed to Larry Clerk, who, as a sen- excellent work in reproducing the radiographs.
ior technician in the Department of Anatomy at the George As in the past, I express my sincere thanks to Myra
Washington University School of Medicine and Health Feldman and Ira Grunther, AMI, for the preparation of the
Sciences, greatly assisted me in the preparation of neu- very fine artwork.
roanatomical specimens for photography. Finally, to the staff of Lippincott Williams & Wilkins, I
I am also grateful to members of the Department of again express my great appreciation for their continued
Radiology for the loan of radiographs and CT scans that have enthusiasm and support throughout the preparation of this
been reproduced in different sections of this book. I am most book.
To My Students—Past,Present,and Future
This book is designed so that the information is presented without masses of confusing detail involving
complicated neural connections.The arrangement permits the students and future health providers
to quickly recall the essential features necessary for the diagnosis and treatment of patients.
iv
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C O N T E N T S
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Color Atlas of Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xi
CHAPTER 1 Introduction and Organization of the Nervous System 1
Chapter Objectives 2
Central and Peripheral Nervous Systems 2
Major Divisions of the Central Nervous System 2
Major Divisions of the Peripheral Nervous System 10
Early Development of the Nervous System 14
Clinical Notes 17
Clinical Problem Solving 28
Answers and Explanations to Clinical Problem Solving 29
Review Questions 30
Answers and Explanations to Review Questions 31
Additional Reading 32
CHAPTER 2 The Neurobiology of the Neuron and the Neuroglia 33
Chapter Objectives 34
Definition of a Neuron 34
Varieties of Neurons 34
Structure of the Neuron 34
Definition of Neuroglia 53
Astrocytes 53
Oligodendrocytes 54
Microglia 57
Ependyma 58
Extracellular Space 59
Clinical Notes 61
Clinical Problem Solving 63
Answers and Explanations to Clinical Problem Solving 64
Review Questions 65
Answers and Explanations to Review Questions 67
Additional Reading 69
CHAPTER 3 Nerve Fibers, Peripheral Nerves, Receptor and Effector Endings,
Dermatomes, and Muscle Activity 70
Chapter Objectives 71
Nerve Fibers 71
Peripheral Nerves 80
Conduction in Peripheral Nerves 84
Receptor Endings 86
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vi Contents
Effector Endings 95
Segmental Innervation of Skin 100
Segmental Innervation of Muscles 100
Muscle Tone and Muscle Action 101
Summation of Motor Units 103
Muscle Fatigue 104
Posture 104
Clinical Notes 107
Clinical Problem Solving 120
Answers and Explanations to Clinical Problem Solving 123
Review Questions 126
Answers and Explanations to Review Questions 129
Additional Reading 131
CHAPTER 4 The Spinal Cord and the Ascending and Descending Tracts 132
Chapter Objectives 133
A Brief Review of the Vertebral Column 133
Gross Appearance of the Spinal Cord 137
Structure of the Spinal Cord 138
The Ascending Tracts of the Spinal Cord 143
Anatomical Organization 143
Functions of the Ascending Tracts 144
The Descending Tracts of the Spinal Cord 153
Anatomical Organization 153
Functions of the Descending Tracts 154
Corticospinal Tracts 155
Reticulospinal Tracts 157
Tectospinal Tract 158
Rubrospinal Tract 159
Vestibulospinal Tract 159
Olivospinal Tract 160
Descending Autonomic Fibers 160
Intersegmental Tracts 161
Reflex Arc 162
Influence of Higher Neuronal Centers on the Activities of Spinal Reflexes 164
Renshaw Cells and Lower Motor Neuron Inhibition 164
Clinical Notes 165
Clinical Problem Solving 177
Answers and Explanations to Clinical Problem Solving 178
Review Questions 181
Answers and Explanations to Review Questions 183
Additional Reading 185
CHAPTER 5 The Brainstem 186
Chapter Objectives 187
A Brief Review of the Skull 187
The Cranial Cavity 192
Introduction to the Brainstem 196
Gross Appearance of the Medulla Oblongata 197
Internal Structure 198
Gross Appearance of the Pons 206
Internal Structure of the Pons 208
Gross Appearance of the Midbrain 210
Internal Structure of the Midbrain 210
Clinical Notes 217
Clinical Problem Solving 221
Answers and Explanations to Clinical Problem Solving 222
Review Questions 224
Answers and Explanations to Review Questions 227
Additional Reading 229
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Contents vii
CHAPTER 6 The Cerebellum and Its Connections 230
Chapter Objective 231
Gross Appearance of the Cerebellum 231
Structure of the Cerebellum 231
Cerebellar Cortical Mechanisms 236
Cerebellar Afferent Fibers 237
Cerebellar Efferent Fibers 240
Functions of the Cerebellum 242
Clinical Notes 243
Clinical Problem Solving 245
Answers and Explanations to Clinical Problem Solving 246
Review Questions 247
Answers and Explanations to Review Questions 249
Additional Reading 250
CHAPTER 7 The Cerebrum 251
Chapter Objectives 252
Subdivisions of the Cerebrum 252
Diencephalon 252
General Appearance of the Cerebral Hemispheres 257
Main Sulci 258
Lobes of the Cerebral Hemisphere 260
Internal Structure of the Cerebral Hemispheres 262
Clinical Notes 271
Clinical Problem Solving 277
Answers and Explanations to Clinical Problem Solving 278
Review Questions 279
Answers and Explanations to Review Questions 281
Additional Reading 283
CHAPTER 8 The Structure and Functional Localization of the Cerebral Cortex 284
Chapter Objective 285
Structure of the Cerebral Cortex 285
Mechanisms of the Cerebral Cortex 287
Cortical Areas 288
Cerebral Dominance 295
Clinical Notes 296
Clinical Problem Solving 298
Answers and Explanations to Clinical Problem Solving 299
Review Questions 300
Answers and Explanations to Review Questions 302
Additional Reading 303
CHAPTER 9 The Reticular Formation and the Limbic System 304
Chapter Objective 305
Reticular Formation 305
Limbic System 307
Clinical Notes 312
Clinical Problem Solving 312
Answers and Explanations to Clinical Problem Solving 313
Review Questions 313
Answers and Explanations to Review Questions 314
Additional Reading 315
CHAPTER 10 The Basal Nuclei (Basal Ganglia) and Their Connections 316
Chapter Objective 317
Terminology 317
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Corpus Striatum 317
Amygdaloid Nucleus 319
Substantia Nigra and Subthalamic Nuclei 319
Claustrum 319
Connections of the Corpus Striatum and Globus Pallidus 319
Connections of the Corpus Striatum 319
Connections of the Globus Pallidus 319
Functions of the Basal Nuclei 320
Clinical Notes 322
Clinical Problem Solving 327
Answers and Explanations to Clinical Problem Solving 327
Review Questions 327
Answers and Explanations to Review Questions 329
Additional Reading 329
CHAPTER 11 The Cranial Nerve Nuclei and Their Central Connections
and Distribution 331
Chapter Objective 332
The 12 Cranial Nerves 332
Organization of the Cranial Nerves 332
Olfactory Nerves (Cranial Nerve I) 335
Optic Nerve (Cranial Nerve II) 336
Oculomotor Nerve (Cranial Nerve III) 340
Trochlear Nerve (Cranial Nerve IV) 340
Trigeminal Nerve (Cranial Nerve V) 341
Abducent Nerve (Cranial Nerve VI) 344
Facial Nerve (Cranial Nerve VII) 346
Vestibulocochlear Nerve (Cranial Nerve VIII) 348
Glossopharyngeal Nerve (Cranial Nerve IX) 350
Vagus Nerve (Cranial Nerve X) 352
Accessory Nerve (Cranial Nerve XI) 354
Hypoglossal Nerve (Cranial Nerve XII) 356
Clinical Notes 358
Clinical Problem Solving 363
Answers and Explanations to Clinical Problem Solving 364
Review Questions 365
Answers and Explanations to Review Questions 368
Additional Reading 369
CHAPTER 12 The Thalamus and Its Connections 371
Chapter Objective 372
General Appearances of the Thalamus 372
Subdivisions of the Thalamus 372
Connections of the Thalamus 375
Function of the Thalamus 375
Clinical Notes 378
Clinical Problem Solving 378
Answers and Explanations to Clinical Problem Solving 378
Review Questions 379
Answers and Explanations to Review Questions 380
Additional Reading 381
CHAPTER 13 The Hypothalamus and Its Connections 382
Chapter Objectives 383
The Hypothalamus 383
Hypothalamic Nuclei 383
Afferent Nervous Connections of the Hypothalamus 385