HUMAN NEURO ANATOMY

JAMES R. AUGUSTINE School of Mediane

University of South Carolina Columbia, South Carolina

AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD

PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO

ELSEVIER Academic Press is an imprint of Elsevier

Contents

V

Preface xv

Chapter 1: Introduction to the Nervous System 3

1.1. Neurons 4 1.1.1. NeuronaTCell Body (Soma) 4 1.1.2. AxonHillo,ck 5 1.1.3. Neuronal Processes - Axons

and Dendrites 5 1.2. Classification of Neurons 6

1.2.1. Neuronal Classification by Function 6 1.2.2. NeuronalClassification byNumber

of Processes 6 1.3. The Synapse 7

1.3.1. Components of a Synapse 8 1.3.2. Neurotransmitters and

Neuromodulators 8 1.3.3. Neuronal Plasticity 8 1.3.4. The Neuropil 9

1.4. Neuroglial Cells 9 1.4.1. Neuroglial Cells differ from Neurons 9 1.4.2. Identification of Neuroglia 9 1.4.3. Neuroglial Function 10 1.4.4. Neuroglial Cells and Aging 11

1.5. Axonal Transport 11 1.5.1. Functions of Axonal Transport 12 1.5.2. Defective Axonal Transport 12

1.6. Degeneration and Regeneration 12 1.6.1. Axon or Retrograde Reaction 13 1.6.2. Anterograde Degeneration 13 1.6.3. Retrograde Degeneration 14 1.6.4. Regeneration of Peripheral Nerves 14 1.6.5. Regeneration and Neurotrophic

Factors 16 1.6.6. Regeneration in the Central Nervous

System 16 1.7. Neural Transplantation 16 Further Reading 17

Chapter 2: Development of the Nervous System 19

2.1. First Week of Development (Fertilization, Free Blastocyst, Attaching Blastocyst) 20 2.1.1. Fertilization 20 2.1.2. From Two Cells to the Free Blastocyst 20

2.2. Second Week of Development (Implantation, Primitive Streak Appears, Three Layers of Cells) 20 2.2.1. Implantation and the Appearance of

Two Distinct Layers of Cells 20 2.2.2. Primitive Streak and a Third Layer

of Cells Appear 22 2.3. Third Week of Development (Neural

Plate, Groove, and Folds, Three Main Divisions of the Brain) 22 2.3.1. Primitive Node and Notochordal

Process Appear 22 2.3.2. Neural Plate, Groove, Folds and

Neuromeres Appear 23 2.3.3. Three Main Divisions of the Brain

Identifiable 24 2.3.4. Mesencephalic Flexure Appears 24

2.4. Fourth Week of Development (Neural Tube Forms and Closes, Neural Crest Formation Continues) 24 2.4.1. Formation of the Neural Tube 24 2.4.2. Rostral and Caudal Neuropores

Remain Temporarily Open 24 2.4.3. Neural Crest Cells Emerge 24 2.4.4. Neural Canal - the Future

Ventricular System 26 2.4.5. Neuropores Close and the Closed

Neural Tube is Filled with Fluid 26 2.4.6. Cervical Flexure Present 26

2.5. Fifth Week of Development (Five Subdivisions of the Brain Identifiable) 27 2.5.1. Simple Tube Transforms into

Complex Organ System 27

VI CONTENTS

2.5.2. Five Subdivisions of the Brain Appear 27 2.5.3. Brain Vesicles vs. Brain Regions 27

2.6. Vulnerability of the Developing Nervous System 28

2.7. Congenital Malformations of the Nervous System 29 2.7.1. Spinal Dysraphism 29 2.7.2. Anencephaly 30

Further Reading 31

Chapter 3: The Spinal Cord 33

3.1. Embryological Considerations 33 3.1.1. Layers of the Developing Spinal Cord 34 3.1.2. Formation of Ventral Gray Columns

and Ventral Roots 34 3.1.3. Formation of Dorsal Gray Columns 35 3.1.4. Dorsal and Ventral Horns vs. Dorsal

and Ventral Gray Columns 35 3.1.5. Development of Neural Crest Cells 36 3.1.6. The Framework of the Adult Cord is

Present at Birth 36 3.2. Gross Anatomy 36

3.2.1. Spinal Cord Weight and Length 36 3.2.2. Spinal Segments, Regions, and

Enlargements 36 3.2.3. Spinal Segments in Each Region are of

Unequal Length 37 3.2.4. Conus Medullaris, Filum Terminale,

and Cauda Equina 37 3.2.5. Termination of the Adult Spinal Cord [ 3.2.6. Differential Rate of Growth: Vertebral

Column vs. the Spinal Cord 38 3.2.7. Relationship between Spinal Segments

and Vertebrae 38 3.3. Nuclear Groups - Gray Matter 39

3.3.1. General Arrangement of Spinal Cord Gray Matter 39

3.3.2. Gray Matter at Enlargement Levels 39 3.3.3. Spinal Laminae 39 3.3.4. Dorsal Hörn 40 3.3.5. Lateral Hörn 40 3.3.6. Ventral Hörn 40

3.4. Functional Classes of Neurons 41 3.4.1. Four Classes of Neurons in the

Spinal Cord 41 3.4.2. General Somatic vs. General Visceral

Afferent Neurons 41 3.4.3. General Somatic vs. General Visceral

Efferent Neurons 41 3.4.4. Some Ventral Root Axons are Sensory

3.5. Funiculi/Fasciculi/Tracts - White Matter 42 3.6. Spinal Reflexes 43 3.7. Spinal Meninges and Related Spaces 44

3.7.1. Spinal Dura Mater 44 3.7.2. Spinal Arachnoid 45 3.7.3. Spinal Pia Mater 45

3.8. Spinal Cord Injury 45 3.8.1. Transverse Hemisection of the

Spinal Cord (Brown-Sequard Syndrome) 45

3.8.2. Syringomyelia 46 3.9. Blood Supply to the Spinal Cord 46 Further Reading 46

Chapter 4: The Brain Stern 49

4.1. External Features 49 4.1.1. Medulla Oblongata 49 4.1.2. Pons 51 4.1.3. Midbrain 52

4.2. Cerebellum and Fourth Ventricle 52 4.2.1. Cerebellum 52 4.2.2. Fourth Ventricle 52

4.3. Organization of Brain Stern Neuronal Columns 53 4.3.1. Functional Components of the

Cranial Nerves 55 4.3.2. Efferent Columns 55 4.3.3. Afferent Columns 55

4.4. Internal Features 57 4.4.1. Endogenous Substances 57 4.4.2. Medulla Oblongata 57 4.4.3. Pons 61 4.4.4. Midbrain 65

Further Reading 68

Chapter 5: The Forebrain 71

5.1. Telencephalon 71 5.1.1. Telencephalon Medium 71 5.1.2. Cerebral Hemispheres 72 5.1.3. Basal Nuclei 77 5.1.4. Rhinencephalon 79

5.2. Diencephalon 79 5.2.1. Epithalamus 79 5.2.2. Thalamus 79 5.2.3. Subthalamus 79 5.2.4. Hypothalamus 80

5.3. Cerebral White Matter 80 Further Reading 80

CONTENTS Vll

Chapter 6: Introduction to Ascending Sensory Paths 83

6.1. Receptors 83 6.2. Classification of Receptors by Modality 84

6.2.1. Mechanoreceptors 84 6.2.2. Thermoreceptors 85 6.2.3. Nociceptors 85 6.2.4. Chemoreceptors 86 6.2.5. Photoreceptors 86 6.2.6. Osmoreceptors 86

6.3. Sherrington's Classification of Receptors 86 6.3.1. Exteroceptors 87 6.3.2. Interoceptors 87 6.3.3. Proprioceptors 87

6.4. Structural Classification of Receptors 87 6.4.1. Free Nerve Endings 87 6.4.2. Endings in Hair Follicles 87 6.4.3. Terminal Endings of Nerves 88 6.4.4. Neurotendinous Spindles 90 6.4.5. Neuromuscular Spindles 90

6.5. Reflex Circuits 91 6.5.1. The Monosynaptic Reflex 91 6.5.2. Complex Reflexes 91

6.6. General Sensory Paths 92 6.6.1. Classification of Sensory Paths by

Function 92 6.7. Organization of General Sensory

Paths 92 6.7.1. Receptors 92 6.7.2. Primary Neurons 92 6.7.3. Secondary Neurons 94 6.7.4. Thalamic Neurons 94 6.7.5. Cortical Neurons 94 6.7.6. Modulation of Sensory Paths 94

Further Reading 95

Chapter 7: Paths for Pain and Temperature 97

7.1. Path for Superficial Pain and Temperature from the Body 98 7.1.1. Modalities 99 7.1.2. Receptors 99 7.1.3. Primary Neurons 100 7.1.4. Secondary Neurons 101 7.1.5. Position of the Lateral Spinothalamic

Tract in the Brain Stern 102 7.1.6. Thalamic Neurons 102 7.1.7. Cortical Neurons 103 7.1.8. Modulation of Painful and Thermal

Impulses 105

7.2. Path for Visceral Pain from the Body 105 7.2.1. Modalities and Receptors 106 7.2.2. Primary Neurons 107 7.2.3. Secondary Neurons 107 7.2.4. Thalamic Neurons 109 7.2.5. Cortical Neurons 109 7.2.6. Suffering Accompanying Pain 109 7.2.7. Visceral Pain as Referred Pain 110 7.2.8. Transection of Fiber Bundles to

Relieve Intractable Pain 111 7.3. The Trigeminal Nuclear Complex 111

7.3.1. Organization of the Trigeminal Nuclear Complex 111

7.3.2. Organization of Entering Trigeminal Sensory Fibers 112

7.4. Path for Superficial Pain and Thermal Extremes from the Head 112 7.4.1. Modalities and Receptors 112 7.4.2. Primary Neurons 113 7.4.3. Secondary Neurons 115 7.4.4. Thalamic Neurons 115

7.5. Path for Thermal Discrimination from the Head 116 7.5.1. Modality and Receptors 116 7.5.2. Primary Neurons 117 7.5.3. Secondary Neurons 117 7.5.4. Thalamic Neurons 117 7.5.5. Cortical Neurons 117

7.6. General Somatic Afferent Components ofVILIXandX 118

7.7. Trigeminal and Other Neuralgias 119 7.7.1. Causes of Trigeminal Neuralgia 119 7.7.2. Methods of Treatment for Trigeminal

Neuralgia 119 7.8. Glossopharyngeal Neuralgia 120 Further Reading 120

Chapter 8: Paths for Touch, Pressure, Proprioception, and Vibration 123

8.1. Path for General Tactile Sensation from the Body 123 8.1.1. Modalities and Receptors 124 8.1.2. Primary Neurons 124 8.1.3. Secondary Neurons 124 8.1.4. Thalamic Neurons 124

8.2. Path for Tactile Discrimination, Pressure, Proprioception, and Vibration from the Body 124 8.2.1. Modalities and Receptors 126 8.2.2. Primary Neurons 129 8.2.3. Secondary Neurons 131

CONTENTS

8.2.4. Thalamic Neurons 134 8.2.5. Cortical Neurons 135 8.2.6. Spinal Cord Stimulation for the

Relief of Pain 137 8.3. Path for Tactile I^crirnination from the Head 138

8.3.1. Modalities and Receptors 138 8.3.2. Primary Neurons 138 8.3.3. Secondary Neurons 138 8.3.4. Thalamic Neurons 139 8.3.5. Cortical Neurons 140

8.4. Path for General Tactile Sensation from the Head 141 8.4.1. Modalities and Receptors 141 8.4.2. Primary Neurons 141 8.4.3. Secondary Neurons and Their

Central Processes 141 8.4.4. Thalamic Neurons 142

8.5. Path for Proprioception, Pressure, and Vibration from the Head 143 8.5.1. Modalities and Receptors 143 8.5.2. Primary Neurons 143 8.5.3. Secondary Neurons 143 8.5.4. Thalamic Neurons 143 8.5.5. Cortical Neurons 143

8.6. Trigeminal Motor Component 144 8.7. Certain Trigeminal Reflexes 145

8.7.1. Mandibular, Masseter, or 'Jaw-Closing' Reflex 145

8.7.2. Corneal Reflex 146 Further Reading 146

10.1.3. Internal Ear 164 10.2. The Ascending Auditory Path 166

10.2.1. Modality and Receptors 166 10.2.2. Primary Neurons 167 10.2.3. Secondary Neurons 167 10.2.4. Tertiary Neurons 169 10.2.5. Inferior Collicular Neurons 169 10.2.6. Thalamic Neurons 169 10.2.7. Cortical Neurons 170 10.2.8. Comments 172

10.3. Descending Auditory Connections 172 10.3.1. Electrical Stimulation of

Cochlear Efferents 173 10.3.2. Autonomie Fibers to the Cochlea 173

10.4. Injury to the Auditory Path 173 10.4.1. Congenital Loss of Hearing 173 10.4.2. Decoupling of Stereocilia 174 10.4.3. Tinnitus 174 10.4.4. Noise-Induced Loss of Hearing 174 10.4.5. Aging and the Loss of Hearing 175 10.4.6. Unilateral Loss of Hearing 175 10.4.7. Injury to the Inferior Colliculi 175 10.4.8. Unilateral Injury to the Medial

Geniculate Body or Auditory Cortex 175 10.4.9. Bilateral Injury to the Primary

Auditory Cortex 175 10.4.10. Auditory Seizures - Audenes 176

10.5. Cochlear Implants 176 10.6. Auditory Brain Stern Implants 176 Further Reading 176

Chapter 9: The Reticular Formation 149

9.1. Structural Aspects 149 9.1.1. Reticular Nuclei in the Medulla 150 9.1.2. Reticular Nuclei in the Pons 153 9.1.3. Reticular Nuclei in the Midbrain 154

9.2. Ascending Reticular System 155 9.3. Descending Reticular System 158 9.4. Functional Aspects of the Reticular Formation 158

9.4.1. Consciousness 158 9.4.2. Homeostatic Regulation 159 9.4.3. Visceral Reflexes 160 9.4.4. Motor Function 160

Further Reading 161

Chapter 10: The Auditory System 163

10.1. Gross Anatomy 163 10.1.1. ExternalEar 163 10.1.2. MiddleEar 163

Chapter 11: The Vestibulär System 179

11.1 Gross Anatomy 179 11.1.1. Internal Ear 179

11.2. The Ascending Vestibulär Path 181 11.2.1. Modalities and Receptors 181 11.2.2. Primary Neurons 184 11.2.3. Secondary Neurons 186 11.2.4. Thalamic Neurons 187 11.2.5. Cortical Neurons 188

11.3. Other Vestibulär Connections 190 11.3.1. Primary Vestibulocerebellar Fibers 190 11.3.2. Vestibulär Nuclear Projections to

the Cerebellum 190 11.3.3. Vestibulär Nuclear Projections to

the Spinal Cord 190 11.3.4. Vestibulär Nuclear Projections to

Nuclei of the Extraocular Muscles 192 11.3.5. Vestibulär Nuclear Projections to

the Reticular Formation 192

CONTENTS IX

11.3.6. Vestibulär Projections to the Contralateral Vestibulär Nuclei 193

11.4. The Efferent Component of the Vestibulär System 193

11.5. Afferent Projections to the Vestibulär Nuclei 193 11.6. Vertigo 193

11.6.1. Physiological Vertigo 194 11.6.2. Pathological Vertigo 194

Further Reading 195

Chapter 12: The Visual System 199

12.1. Retina 199 12.1.1. Pigment Layer 199 12.1.2. Neural Layer 200 12.1.3. Other Retinal Elements 200 12.1.4. Special Retinal Regions 201 12.1.5. Retinal Areas 202 12.1.6. Visual Fields 202

12.2. Visual Path 204 12.2.1. Receptors 204 12.2.2. Primary Retinal Neurons 205 12.2.3. Secondary Retinal Neurons 205 12.2.4. Optic Nerve [II] 207 12.2.5. Optic Chiasma - the Union of Both

Intracranial Optic Nerves 208 12.2.6. Optic Tract 209 12.2.7. Thalamic Neurons 209 12.2.8. Optic Radiations 210 12.2.9. Cortical Neurons 211

12.3. Injuries to the Visual System 214 12.3.1. Retinal Injuries 214 12.3.2. Injury to the Optic Nerve 214 12.3.3. Chiasmal Injuries 215 12.3.4. Injuries to the Optic Tract 215 12.3.5. Injury to the Lateral Geniculate Body 215 12.3.6. Injuries to the Optic Radiations 216 12.3.7. Injuries to the Visual Cortex 216

Further Reading 217

Chapter 13: Ocular Movements and Visual Reflexes 219

13.1. Ocular Movements 219 13.1.1. Primary Position of the Eyes 219

13.2. Conjugate Ocular Movements 220 13.2.1. Miniature Ocular Movements 220 13.2.2. Saccades 220 13.2.3. Smooth Pursuit Movements 221 13.2.4. Vestibulär Movements 221

13.3. Extraocular Muscles 221 13.4. Innervation of the Extraocular Muscles 222

13.4.1. Abducent Nucleus and Nerve 223 13.4.2. Trochlear Nucleus and Nerve 224 13.4.3. Oculomotor Nucleus and Nerve 225

13.5. Anatomical Basis of Conjugate Ocular Movements 227

13.6. Medial Longitudinal Fasciculus 228 13.7. Vestibulär Connections Related to Ocular

Movements 229 13.7.1. Vestibulär Connections Related to

Horizontal Ocular Movements 229 13.7.2. Vestibulär Nystagmus 229 13.7.3. Doll's Ocular Movements 230 13.7.4. Vestibulär Connections Related to

Vertical Ocular Movements 231 13.8. Injury to the Medial Longitudinal Fasciculus 231 13.9. Injury to the Vestibulär Nuclei 231 13.10. The Reticular Formation and Ocular

Movements 232 13.11. Congenital Nystagmus 232 13.12. Ocular Bobbing 233 13.13. Examination of the Vestibulär System 233 13.14. Visual Reflexes 234

13.14.1. The Light Reflex 235 13.14.2. The Near Reflex 236 13.14.3. Pupillary Dilatation 236 13.14.4. The Lateral Tectotegmentospinal

Tract 237 13.14.5. Pupillary Pain Reflex and the

Spinotectal Tract 238 13.14.6. The Afferent Pupillary Defect

(Marcus Gunn Pupillary Sign) 238 Further Reading 238

Chapter 14: The Thalamus 241

14.1. Introduction 241 14.2. Nuclear Groups of the Thalamus 245

14.2.1. Anterior Nuclei and the Lateral Dorsal Nucleus 245

14.2.2. Intralaminar Nuclei 246 14.2.3. Medial Nuclei 247 14.2.4. Median Nuclei 248 14.2.5. Metathalamic Body and Nuclei 249 14.2.6. Posterior Nuclear Complex 250 14.2.7. Pulvinar Nuclei and Lateral

Posterior Nucleus 250 14.2.8. Reticular Nucleus 251 14.2.9. Ventral Nuclei 251

14.3. Injuries to the Thalamus 254

CONTENTS

14.4. Mapping the Human Thalamus 255 14.5. Stimulation of the Human Thalamus 255 14.6. The Thalamus as a Neurosurgical Target 256 Further Reading 256

Chapter 15: The Motor System: Part 1 - Lower Motoneurons and the Pyramidal System 259

15.1. Regions Involved in Motor Activity 259 15.2. Lower Motoneurons 260

15.2.1. Terms Related to Motor Activity 260 15.2.2. Lower Motoneurons in the

Spinal Cord 260 15.2.3. Activation of Motoneurons 261 15.2.4. Lower Motoneurons in the Brain Stern 261 15.2.5. Injury to Lower Motoneurons 263 15.2.6. Examples of Lower Motoneuron

Disorders 263 15.3. Pyramidal System 263

15.3.1. Corticospinal Component 263 15.3.2. Corticobulbar Component 270 15.3.3. Clinical Neuroanatomical Correlation 274

Further Reading 274

Chapter 16: The Motor System: Part 2 - The Extrapyramidal System and Cerebellum 277

16.1. Extrapyramidal System 277 16.1.1. Extrapyramidal Motor Cortex 278 16.1.2. Basal Nuclei 279 16.1.3. Äfferents to the Basal Nuclei 282 16.1.4. Cortical-striatal-pallidal-thalamo-

cortical Circuits 282 16.1.5. Multisynaptic Descending Paths 282 16.1.6. Common Discharge Paths 283 16.1.7. Somatotopic Organization of the

Basal Nuclei 283 16.2. Cerebellum 283

16.2.1. External Features of the Cerebellum 284 16.2.2. Cerebellar Cortex 286 16.2.3. Deep Cerebellar Nuclei 287 16.2.4. Cerebellar White Matter 287

16.3. Input to the Cerebellum through the Peduncles 287 16.3.1. Inferior Cerebellar Peduncle 287 16.3.2. Middle Cerebellar Peduncle 288 16.3.3. Superior Cerebellar Peduncle 288

16.4. Input to the Cerebellum 289 16.4.1. Incoming Fibers to the

Cerebellum 289 16.5. Cerebellar Output 289

16.5.1. Output from the Fastigial Nuclei 289 16.5.2. Output from the Globose and

Emboliform Nuclei 290 16.5.3. Output from the Dentate Nuclei 290

16.6. Cerebellar Circuitry 290 16.7. Common Discharge Paths 290 16.8. Cerebellar Functions 291

16.8.1. Motor Functions of the Cerebellum 291

16.8.2. Nonmotor Functions of the Cerebellum 291

16.8.3. Studies Involving the Human Cerebellum 291

16.8.4. Localization in the Cerebellum 291 16.9. Manifestations of Injuries to the

Motor System 291 16.9.1. Injury to the Premotor Cortex 291 16.9.2. Injuries to the Basal Nuclei 292 16.9.3. Injury to the Subthalamic

Nucleus 294 16.9.4. Injury to the Cerebellum 294 16.9.5. Localization of Cerebellar

Damage 295 16.10. Decorticate Versus Decerebrate

Rigidity 296 16.10.1. Decerebrate Rigidity 296 16.10.2. Decorticate Rigidity 296

16.11. Epilogue 296 Further Reading 296

Chapter 17: The Olfactory and Gustatory Systems 299

17.1. The Olfactory System 299 17.1.1. Receptors 300 17.1.2. Primary Neurons 300 17.1.3. Olfactory Fila and the Olfactory

Nerve 300 17.1.4. Olfactory Bulb - Secondary

Olfactory Neurons 300 17.1.5. Olfactory Stalk 301 17.1.6. Medial Stria 301 17.1.7. LateralStria 301 17.1.8. Thalamic Neurons 302 17.1.9. Cortical Neurons 302 17.1.10. Efferent Olfactory Connections 303

CONTENTS

17.1.11. Injuries to the Olfactory System 303

17.2. The Gustatory System 304 17.2.1. Receptors 304 17.2.2. Primary Neurons 306 17.2.3. Secondary Neurons 308 17.2.4. The Ascending Gustatory Path 308 17.2.5. Thalamic Neurons 308 17.2.6. Cortical Neurons 309 17.2.7. Injuries to the Gustatory System 309

Further Reading 310

Chapter 18: The Limbic System 313

18.1. Historical Aspects 313 18.2. Anatomy of the Limbic System 314

18.2.1. Olfactory System 314 18.2.2. Septal Area 315 18.2.3. Mamillary Bodies of the

Hypothalamus 315 18.2.4. Anterior Nuclei of the

Thalamus 315 18.2.5. The Hippocampal Formation 315 18.2.6. The Amygdaloid Body 316 18.2.7. Cingulate Gyrus and Cingulum 318 18.2.8. Cortical Areas 318

18.3. Cyclic Paths of the Limbic System 318 18.4. Synaptic Organization of Human

Limbic System 320 18.5. Descending Limbic Paths 320 18.6. Functional Aspects of the Human

Limbic System 321 18.6.1. Emotion 321 18.6.2. Memory 322

18.7. Limbic System Disorders 322 18.8. Injuries to Limbic Constituents 323

18.8.1. Septal Area 323 18.8.2. Hippocampal Formation 323 18.8.3. Amygdaloid Body 323 18.8.4. Seizures Involving the Limbic

System 323 18.9. Psychosurgery of the Limbic System 323

18.9.1. Drug Resistant Epilepsy 324 18.9.2. Violent, Aggressive, or Restless

Behaviors 324 18.9.3. Schizophrenia 324 18.9.4. Intractable Pain 324 18.9.5. Psychiatric Disorders and Abnormal

Behavior 324 Further Reading 324

Chapter 19: The Hypothalamus 327

19.1. Hypothalamic Regions 328 19.2. Hypothalamic Zones 329 19.3. Hypothalamic Nuclei 330

19.3.1. Anterior Hypothalamic Region 330 19.3.2. Dorsal Hypothalamic Region 330 19.3.3. Intermediate Hypothalamic Region 332 19.3.4. Lateral Hypothalamic Area 332 19.3.5. Posterior Hypothalamic Region 332 19.3.6. Posterior Nucleus of the

Hypothalamus 333 19.4. Fiber Connections 333

19.4.1. Medial Forebrain Bündle 333 19.4.2. Stria Terminalis 333 19.4.3. Fornix 333 19.4.4. Diencephalic Periventricular

System (DPS) 333 19.4.5. Dorsal Longitudinal Fasciculus 333 19.4.6. Anterior and Posterior

Hypothalamotegmental Tracts 334 19.4.7. Pallidohypothalamic Tract 334 19.4.8. Mamillothalamic Tract 334 19.4.9. Hypothalamo-hypophyseal Tract 334 19.4.10. Vascular Connections 334

19.5. Functions of the Hypothalamus 334 19.5.1. Water Balance - Water Intake

and Loss 334 19.5.2. Eating - Food Intake 335 19.5.3. Temperature Regulation 335 19.5.4. Autonomie Regulation 335 19.5.5. Emotional Expression 335 19.5.6. Wakefulness and Sleep

(Biological Rhythms) 336 19.5.7. Control of the Endocrine System 336 19.5.8. Reproduction 336

Further Reading 336

Chapter 20: The Autonomie Nervous System 339

20.1 Historical Aspects 339 20.2. Structural Aspects 340

20.2.1. Location of Autonomie Neurons of Origin 340

20.2.2. Manner of Distribution of Autonomie Fibers 341

20.2.3. Termination of Autonomie Fibers 342 20.3. Comparison of the Somatic Efferents

and Visceral Efferents 343 20.4. General Visceral Afferents 345

CONTENTS

20.5. Regulation of the Autonomie Nervous System 346

20.6. Disorders of the Autonomie Nervous System 346

Further Reading 347

Chapter 21: General Features of the Cerebral Hemispheres 349

21.1. Facts and Figures 349 21.2. Cortical Neurons 350 21.3. Cortical Lay er s 351 21.4. Cortical Columns (Microarchitecture) 352 21.5. Functional Aspects of the Cerebral

Cortex 353 21.6. Cerebral Dominance, Lateralization, and

Asymmetry 353 21.7. Frontal Lobe 353

21.7.1. Primary Motor Cortex 353 21.7.2. Premotor Cortex 354 21.7.3. Supplementary Motor Area (SMA) 355 21.7.4. Cingulate Motor Areas 355 21.7.5. Frontal Eye Fields 355 21.7.6. Motor Speech Region 356 21.7.7. Prefrontal Cortex 356

21.8. Parietal Lobe 357 21.8.1. Primary Somatosensory

Cortex (SI) 358 21.8.2. Secondary Somatosensory

Cortex 360 21.8.3. Superior Parietal Lobule 361 21.8.4. Inferior Parietal Lobule: Language

Areas 361 21.8.5. Primary Vestibulär Cortex (2v) 362 21.8.6. Mirror Representation of Others'

Actions 362 21.8.7. Preoccipital Areas Involved in

Following Ocular Movements 362 21.9. Occipital Lobe 363

21.9.1. Primary Visual Cortex (VI) 363 21.9.2. Secondary Visual Cortex 363

21.10. Temporal Lobe 363 21.10.1. Primary Auditory Cortex (AI) 364 21.10.2. Wernicke's Region 364 21.10.3. Temporal Vestibulär Cortex 364 21.10.4. Midtemporal Areas Related to

Memory 365 21.10.5. Anomia 365 21.10.6. Prosopagnosia 365 21.10.7. Psychomotor Seizures 365

21.11. Insular Lobe 366

21.12. Aphasia 366 21.12.1. Historie Aspects of Aphasia 367 21.12.2. Broca's Aphasia 367 21.12.3. Wernicke's Aphasia 368 21.12.4. Conductive Aphasia 368 21.12.5. Global Aphasia 368

21.13. Alexia 368 21.14. Apraxia 368 21.15. Gerstmann's Syndrome 369 21.16. Agnosia 369 21.17. Dyslexia 369 Further Reading 369

Chapter 22: Blood Supply to the Central Nervous System 373

22.1. Cerebral Circulation 373 22.2. Aortic Arch, Brachiocephalic Trunk, and

Subclavian Vessels 374 22.3. Vertebral-Basilar Arterial System 374

22.3.1. Branches of the Vertebral Arteries 375 22.4. Blood Supply to the Spinal Cord 376

22.4.1. Extramedullary Vessels 376 22.4.2. Intramedullary Vessels 379 22.4.3. Spinal Veins 380

22.5. Blood Supply to the Brain Stern and Cerebellum 380 22.5.1. Extrinsic or Superficial Branches 380 22.5.2. Branches of the Basilar Arteries 382 22.5.3. Intrinsic or Penetrating Branches 383 22.5.4. Classical Brain Stern Syndromes 385

22.6. Common Carotid Artery 386 22.6.1. External Carotid Artery 386 22.6.2. Internal Carotid Artery: Cervical,

Petrous, and Cavernous Parts 387 22.7. Blood Supply to the Cerebral

Hemispheres 387 22.7.1. Internal Carotid Artery:

Cerebral Part 387 22.7.2. Branches of the Internal

Carotid Artery 388 22.7.3. Posterior Cerebral Artery and its

Cerebral Supply 391 22.8. Cerebral Arterial Circle 392

22.8.1. Types of Arteries Supplying the Brain 392

22.9. Embryological Considerations 392 22.10. Vascular Injuries 392

22.10.1. Brain Stern Vascular Injuries 393 22.10.2. Visualization of Brain Vessels 393

Further Reading 393

CONTENTS xiu

Chapter 23: The Meninges, Ventricular Syst« and Cerebrospinal Fluid 395

23.1. The Cranial Meninges and Related Spai 23.1.1. Cranial Dura Mater 395 23.1.2. Cranial Arachnoid 395 23.1.3. Cranial Pia Mater 398 23.1.4. Dural Projections 398 23.1.5. Intracranial Herniations 399

23.2. Ventricular System 400 23.2.1. Introduction 400 23.2.2. Lateral Ventricles 400

23.2.3. Third Ventricle 401 23.2.4. Aqueduct of Midbrain 402 23.2.5. Fourth Ventricle 402

395 23.3. Cerebrospinal Fluid 403 Further Reading 403

References 406

Index 461