Textbook of Clinical Neuroanatomy Kanchan Kapoor
INDEX
Page numbers followed by f refer to figure, fc refer to flowchart, and t refer to table.
A
Abdomen 40f
Abducent nerve 56, 244
nucleus of 99, 104, 246f
Acalculia 171
Accessory cuneate nucleus 91
Accessory nerve 95
cranial part of 248
spinal part of 89
Accessory oculomotor nucleus 113
Acetylcholine 27, 28
Adrenaline 27, 28
Adrenergic fibers 42
Afferent columns 242
Afferent fibers 112, 114, 127
Afferent limb 261, 262
Afferent nucleus 241
Agraphia, left 179
Alar
derivatives of 7t
lamina 5, 241, 242
lamina, formation of 5f
plate, cells of 6f
Allocortex 9
Alveus 200, 210
Alzheimer's disease 203
Amblyopia 263
Ampulla 265, 266
Amygdala 141, 190
connections of 197, 197f, 198fc
Amygdaloid body 190
Amygdaloid nuclear complex 186, 190, 196, 197f, 205
Amyotrophic lateral sclerosis 84f, 85
Anal reflex 81
Ancient cortex 170
Anencephaly 10, 11f
Anesthesia
epidural 61, 235
general 30
Angular gyrus 162
Anhidrosis 45, 96
Anomia 171
Anosmia 258
Anosognosia 171
Ansa lenticularis 153, 189
Anterior cerebral
artery 167, 170f, 171, 220222, 224
vessels 177
Anterior choroidal artery 220
Anterior communicating artery 221, 224
Anterior corticospinal tract 75f, 76
Anterior external arcuate fibers 92, 130
Anterior funiculus 64
Anterior horn 209, 210f
cells 179
Anterior lobe 120
lesions 133
Anterior spinal artery syndrome 81, 83, 96, 219
Anterograde amnesia 203
Antidiuretic hormone 150
Aphasia 171, 172, 224
expressive 164
receptive 172
Appendix 33
Apraxia
construction 171
dressing 171
Aprosodia 172
Arachnoid mater 55, 58, 62, 229, 233, 235, 237
modifications of 233
Arachnoid villi 233
Arachnoidal granulations 233
Archicerebellum 122
Archipallium 170
Arcuate fasciculus 176
Arcuate fibers, posterior external 91
Arcuate nucleus 148
Arcus parieto-occipitalis 162
Areolar tissue containing 237
Arnold-Chiari
malformation 12, 214
syndrome 12f
Arteria radicularis magna 82, 217
Artery of Adamkiewicz 82
Artery of Heubner 183, 222
recurrent 183, 222
Artery
lenticulostriate 222
part of 220
plexus around 39
thalamogeniculate 222
thalamoperforating 154
Aspartate 27
Astereognosis 166, 171, 172
Asthenia 133
Astrocytes 19
Astrocytoma 20
Asynergia 133
Ataxia 133
Athetosis 192
Auditory pathway 146, 264, 264f, 265fc
Auditory radiation 167
Auditory reflex 117
fiber, part of 103
Auditory verbal agnosia 172
Automatic bladder 51
Autonomic fibers, descending 78
Autonomic ganglia 34
Autonomic nervous system 16, 36, 37f, 41
divisions of 36
Autonomic pathway 37fc
Autonomic plexuses 39
Autonomous bladder 51
Axial sulcus 159
Axillary nerve 26
Axodendritic synapse 28f
Axolemma 22
Axon 17, 17t
hillock 16
length of 18
Axonotmesis 25
Axoplasmic flow 18
Axoplasmic transport, role of 19
Axosomatic synapse 28f
B
Babinski sign 81
Ballism 192
Band of Baillarger 169
Basal forebrain 256
Basal ganglia 157, 168, 175, 186
Basal lamina 5, 5f, 7t, 241, 242
Basal nucleus 157, 158f, 186, 189f
blood supply of 192
components of 187fc
connections of 189fc
functions of 192
Basilar artery 106, 116
branches of 220, 221f
Basket cells 124, 125, 128
Bell's palsy 246
Benedikt syndrome 116, 116f
Berry aneurysm 221
Binocular visual field 260f
Bipolar cells 259
Bipolar neurons 18
Bitemporal heteronymous hemianopia 263
Biventral lobule 121, 122
Blind spot 259
Blood 237f
brain barrier 227
structure of 227, 227f
nerve barrier 23
plasma 237t
supply, intrinsic 82, 218
vessels 43
Body, dermatomes of 33f
Brachial plexus 26
Brachium 109
inferior 109, 112, 146f
Bradykinesia 193
Brain 1, 15, 22, 23f, 55, 61f, 75, 155f
arterial supply of parts of 226t
base of 56f, 58
blood supply of 219
branches of arteries of 220t
cerebral hemisphere of 139f
development of 2
ventricles of 5f
devoid, areas of 227
drainage of base of 225f
flexures of 3
herniation of 230
midsagittal section of 138f
mode of circulation in 224
parts of 4fc, 55, 226
small 119
specimen 56f, 160f, 163f, 188f
venous drainage of 224
ventricles of 57f, 207
ventricular system of 207f
vesicles, development of 3f
Brainstem 7t, 36, 56, 73, 88, 119f, 142, 146f, 168, 179, 204, 242f
connections with 196
dorsal aspect of 89f, 100f, 110f
part of 99
reticular formation in 203, 203f, 203t
veins of 227
ventral aspect of 89f, 100f, 110f
vestibular nucleus of 127
Branchiomotor fibers 240
Broca's motor speech area 172
Brown-Séquard syndrome 84, 84f
Buerger's disease 52
Bulbar palsy 88, 90
Bundle of Vicq D'Azir 201
C
Calamus scriptorius 213
Calcarine sulcus 144, 162
posterior part of 159
Callosal syndrome 178
Callosomarginal branch 222
Capillary endothelium 237
Cardiac muscle, contraction of 48
Cardiac pain, referred 48
Cardiac plexus 39
Carotid
angiogram 270
sinus reflex 248
siphon 220
Cauda equina 5, 61, 61f, 62, 235
Caudal anesthesia 62, 235
Caudate nucleus 9, 186, 188, 188f
Cavernous sinus 232, 233f
thrombosis 231
Celiac ganglion 39
Celiac plexus 39
Cell body 16, 64, 267
shape of 18
Cell of Cajal 168
Cell
horizontal 18
star-shaped 19
supporting 265
types of 168f
Cells of Cajal 168
Cells of Martinotti 168
Central nervous system 2, 15, 36, 55, 175, 203, 217
blood supply of 217
development of 1
meninges of 229
Central tegmental tract 101
Centromedian nucleus 139, 143
Cephalic flexure 3
Cerebellar artery
anterior inferior 106, 133, 135, 220
anterior superior 106
posterior inferior 95, 96, 96f, 133, 135, 220
superior 116, 133, 135, 221
Cerebellar cortex 7, 123, 123f, 127, 132
intrinsic neurons of 125t
layer of 125
parts of 127
structure of 123
Cerebellar glomerulus, structure of 126f
Cerebellar hemisphere 7, 132
Cerebellar islands 125
Cerebellar nucleus 7, 56, 126, 126f, 131, 164
Cerebellar peduncle 127, 128, 130f, 130t
components of inferior 94t
formation of inferior 94
inferior 55, 89, 9194, 96, 101, 129, 130
middle 6, 55, 99, 128130
superior 55, 111, 117, 128, 130
Cerebellar plate 7
Cerebellocortical pathways 131
Cerebello-olivary fibers 131
Cerebellopontine angle 99, 131
Cerebelloreticular fibers 131
Cerebellospinal pathways 131
Cerebellovestibular fibers 131
Cerebellum 55, 57f, 72, 88, 89, 105, 119, 119f, 120, 127, 128, 130133, 204, 226, 227, 246
arterial supply of 133
blood supply of 134f
connections of 128, 129f
development of 7, 8f
functional localization in 132
functional subdivisions of 123f
functions of 131
nucleus of 132t
inferior surface of 120f
internal structure of 123
intrinsic neuronal circuit of 127, 128f
lobes of 120
microanatomy of 124f, 125f
morphological subdivisions of 122t
nucleus of 132t
parts of 120
phylogenetic subdivisions of 122t
rule of three 133, 134t
sections of 120
subdivisions of 121f, 122
superior surface of 120f
surfaces of 120
transverse subdivisions of 121f
vermis of 122f
white matter of 127
Cerebral angiography 270, 271
Cerebral aqueduct 4, 8, 57, 111, 207
Cerebral artery
middle 165, 168, 170f, 170, 220, 224, 261
posterior 116, 167, 170, 170f, 173, 221, 224, 261
Cerebral cortex 9, 18, 36, 69, 70, 71, 76, 100, 131, 143f, 147, 158f, 163, 167, 168f, 170, 172t, 175, 187, 248, 251
arterial supply of 170
laminae of 168, 169f
microanatomy of 169f, 170f
nerve cells of 168t
neurons in 168
postcentral gyrus of 267
structure of 167
types of 170
Cerebral dominance 173f
Cerebral functions, lateralization of 173f
Cerebral hemisphere 9, 36, 55, 157, 158, 158f160f, 164f, 165f, 170f, 171f, 175, 176f, 181f, 186, 199f, 222, 225f, 226, 261f
development of 9f
external features of 158
inferior surface of 162
medial surface of 162, 223f
superolateral surface of 161
veins of 224
white matter of 175
Cerebral hemorrhage 183, 222
Cerebral part, branches of 220
Cerebral peduncles 109, 110, 222
Cerebral vein
inferior 225
internal 225
superficial 225, 225f
Cerebrospinal fluid 6, 20, 57, 58, 62, 229, 233, 235, 237t, 238, 272f
barrier 236, 237, 237f
blockage of 236
characteristic features of 236
circulation of 236, 236f
drainage of 236
production of 236
route of 236fc
Cerebrovascular accident 183
Cerebrum 55, 57, 57f, 157, 157f, 161f, 178f, 189f, 204, 225f
coronal section of 158f, 186f
development of 9
exposed, insula of 162f
inferior aspect of 163f
superficial veins of 225t
white matter of 176fc, 273f
Cervical
enlargement 60
flexure 3, 4f
nerves 22, 63
part 220
plexus 26
segments 65
spine, fifth 63
sympathetic chain 39
Charcot's artery 183, 222
Cholinergic fibers 42
Chorea 192
Choreiform movements 146
Choroid fissure 199, 208
Choroid plexus 208, 208f, 211, 212, 214, 215f
Choroidal arteries 116
Ciliary body 9
Ciliary ganglion 242, 262
Ciliary muscles 262
Ciliary nerves 242
Cingulate gyrus 162, 195f
Cingulum 176
Circadian rhythm 151, 205
Circle of Willis 220, 221, 222
Circular sulcus 162
Circulus arteriosus 221, 221f
Circumvallate papillae 267
Circumventricular organs 151, 227
Cisterna ambiens 234
Cisternal puncture 234
Clarke's column 72
Claustrum 189f, 190
Climbing fibers 127
Cocaine 34
Coccyx 60
Cochlear fibers 264
Cochlear nucleus 105
dorsal and ventral 94, 101, 264
Collateral sulcus 162
Colliculus 109
brachium of
inferior 109
superior 109, 137
connections of superior 114, 114fc, 115f
inferior 109, 110, 264
superior 77, 109, 110, 112, 114
level of 113f
Commissural fibers 175, 175f, 177, 180
Communicating artery, posterior 154, 220, 221
Communication, symbol of 172f
Complete sulcus 159
Computed tomography scan 272
Conjugate movements 164
Connexus interthalamicus 137
Contralateral cerebellar hemisphere 100
Contralateral homonymous hemianopia 172
Contralateral sensory loss 172
Conus medullaris 5, 60, 61f
Cord, dimensions of 60
Cordotomy 74
anterolateral 74
Cornu ammonis 199
Corona radiata 179, 179f
Corpora quadrigemina 109, 110, 117
Corpus callosum 9, 10, 162, 163f, 177, 178f, 179, 209, 211
connections of 178
fiber systems of 178f
functions of 178
parts of 177f, 178f
Corpus striatum 141, 186, 187, 189f, 190, 226
connections of 188, 190f, 197
development of 9
functions of 189
Cortical branches 222, 224
Cortical neurons 168
Cortical paraplegia 171
Corticobulbar tracts 77
Corticocerebellar pathways 131
Corticonuclear fibers, part of 262
Corticopontocerebellar pathway 100, 131
Corticospinal decussation 90
Corticospinal tract 68, 75, 91
course of 76fc
formation of 76fc
lateral 91
somatotopic lamination of 79f
Corticotropin releasing hormone 150
Cranial fossa, middle 232
Cranial nerve 15, 41, 56f, 22, 255
distribution of 252t
emergence of 23f, 58
functional components of 240, 242
ganglia 34
lower four 94
nucleus 57, 94, 95t, 103, 104t, 109, 115, 115t, 179, 242f, 244t, 250t
classification of 241f
location of 243f
origin of 252t
Cranial parasympathetic outflow 40
Cranial ultrasound 272
Craniorachischisis 10f, 11f, 12
Craniosacral outflow 37f, 42
Cremasteric reflex 81
Crista 265
Crus cerebri 8, 76, 110
Cuneate tubercles 90
Cuneatus nucleus 104
Cuneocerebellar tract 73, 130
Cupula 266
Cystic swelling 11
Cytoplasmic organelles 30
D
Dandy-Walker malformation 12
Deep cardiac plexuses 39
Deep cerebellar nuclei 126
Deep facial vein 231
Deep tendon reflexes 77
Deep traumatic injury 64
Deiters nucleus 246
Dejerine-Roussy thalamic syndrome 145
Dementia 203
Dendrites 17, 17t, 64, 256, 267
Dense fibrous tissue 229
Dentate gyrus 196f, 199, 200, 200f
Dentate nucleus 126, 132
Dentato-rubro-thalamic fibers 112
Dermatomes 33
Diaphragm 33
Diaphragma sellae 229, 230
Diencephalon 2, 8, 137, 204
arterial supply of 154, 154f
connections with 197
development of 8
nuclear groups of 138t
parts of 138f
Dilator pupillae 45
Diplegia, crossed 91
Dizziness 271
Dopamine 27, 28, 192, 201
Dorsal accessory olivary nucleus 93
Dorsal root
cells 18
ganglia 34, 74
Dorsal tegmental decussation 113
Dorsolateral tract of Lissauer 72
Dura mater 55, 58, 61, 229, 235, 237
blood supply of 231
modifications of 229
nerve supply of 230
Dysarthria 133
Dysdiadokokinesia 133
Dyskinesia 187, 192
types of 192
E
Ear, inner 265f
Ectoderm 1
Edinger-Westphal nucleus 113, 115, 242, 262
Efferent 240
autonomic pathway 37
columns 242
connections 150, 189, 204
fibers 24, 112, 114, 127, 129f
limb 261, 262
nucleus 241
Electrolytes 236
Electron microscope 27f
Emboliform 132
nucleus 126
Emotional behavior 151
Encephalocele 11, 11f
Encephalon 15
Endocrine activity, control of 151
Endolymph 266
Endoneurium 22
Endoplasmic reticulum 16
Endorphins 28
Endosteal dura, outer 229
Endosteum 61, 235
Enophthalmos 45, 96
Ependyma 207
Ependymal cells 4, 19f, 20
Ependymomas 20
Epidural space 58, 61, 229, 235
Epilepsy, intractable 178
Epiphysis cerebri 152
Epithalamus 8, 151
Equilibrium, disorders of 85, 128
Erb's paralysis 34
Extradural space 58, 229, 230
Extrageniculate retinocortical pathway 115f
Extrapyramidal tracts 75, 77
Eye 43
convergence of 262
right 259
visual field for 259
Eyeball 45
autonomic innervation of 46fc
extrinsic muscles of 242
F
Face, dangerous area of 231
Facial colliculi, level of 102f
Facial colliculus 102, 104, 213
formation of 102
Facial nerve 56, 244, 247f, 251
fibers 102f
course of 247f
infranuclear lesion of 246t
internal genu of 102
nuclei of 104
paralysis of 246
supranuclear lesion of 246t
Facial nucleus 101
Faciobrachial monoplegia 183, 222
Falx cerebelli 229, 230
Falx cerebri 229
Fascia, superficial 237
Fasciculus 22
cuneatus 70, 73, 74, 91
dorsal longitudinal 149
gracilis 70, 71, 73
inferior longitudinal 177
lenticularis 153, 189
medial longitudinal 78, 114, 248
septomarginalis 79
superior longitudinal 176, 262
Fastigial nucleus 126, 127, 132
Fatigue 29
Fibers 150
ascending 68, 181f
association 175, 176, 180
bundles, projection 179
conticopontine 117
corticofugal 182
corticohypothalamic 149
corticonuclear 99, 100, 117, 182
corticoreticular 183
corticorubral 183
corticospinal 99, 100, 110, 117, 182
corticostriate 183
corticothalamic 182
descending 65, 68, 100, 182
extrapyramidal 183
extrinsic 127
internal arcuate 71, 91
intrinsic 127
long-association 176
nonmyelinated 25
olivocerebellar 93, 127, 130
parallel 125
parietopontine 182
parolivocerebellar 130
postganglionic 39, 47, 51
preganglionic 41, 49
projection 175, 175f, 179, 179f, 180
reticulocerebellar 130
reticulospinal 101
rubrocerebellar 127
short-association 176
somatic afferent 16, 24
sympathetic 44, 68
temporopontine 182
trigeminal 143
trigeminocerebellar 130
Fibrous astrocyte 19f
Field of vision, peripheral loss of 263
Fields of Forel 191
Filum terminale 5, 60, 61f, 62, 63, 235
Fimbria 200, 210
Finger agnosia 171
First-order neurons 69, 72, 264, 266, 267
Fissura prima 120
Fissure 120
anterior median 62, 64, 88
horizontal 120
longitudinal 158
posterolateral 120
primary 120
Flexures, formation of 4f
Flocculonodular lobe 7, 120, 122
Folium 121
Foramen of Magendie 214, 234
Foramina of Luschka 214, 234
Forceps
major 178
minor 178
Forebrain
bundle, medial 149
vesicle 2
Fornix 202
commissure of 177, 202
parts of 202f
Fourth ventricle 212
cavity of 214f
choroid plexuses of 214
floor of 213f
Fovea
centralis 258
inferior 213
superior 213
Foville syndrome 106, 106f
Frey's syndrome 25
Frontal eye field 164, 172, 262
Frontal gyrus
inferior 161
middle 161
superior 161
Frontal lobe
effects of damage to 164
functional areas of 165t
Frontal operculum 162
Frontal pole 158
Fronto-occipital fasciculus 177
Frontopontine fibers 182
Functional nuclear columns 244t
Funiculus
lateral 65
posterior 64
separans 213
Fusiform cell 168
G
Gag reflex 248
Gamma-aminobutyric acid 27, 28
Ganglia 1, 34, 38, 44, 69
Ganglion 255
cells 259
inferior 267
Ganglionic blocking agents 34
Ganglionic layer 169
Gastrointestinal glands 45
Gastrointestinal tract 43
autonomic nerve supply of 44
Gemmules 18
General sensory receptors 30t
General somatic afferent 104, 241, 244, 245, 247, 249
fibers 240, 243, 246, 249
General somatic efferent 94, 104
General visceral afferent 241, 244, 249
fibers 240
General visceral efferent 37f, 95, 104, 240, 241, 244, 247, 249
column 94
fibers 248
neurons 37f
Geniculate body
connections of
lateral 147fc
medial 146f, 146fc
lateral 8, 139, 147, 258, 260, 260f
structure of lateral 147f
Geniculocalcarine tract 258, 260
Genu 177, 180
Germ cell tumors 12
Glaucoma 263
Glioblast cells 1
Globose nuclei 126, 132
Globus pallidus 9, 143, 188
Glomeruli 125
structure of 126
Glossopharyngeal afferents 43
Glossopharyngeal nerve 95, 248, 248t, 251, 267
nucleus 248f
Glutamate 27, 28
Gluteal nerves 27
Gluteal reflex 81
Glycine 27
Golgi apparatus 16
Golgi cells 124, 125, 128
Golgi neurons 125, 126
Golgi tendon organs 32
Golgi type 17
Gonadotropin releasing hormone 150
Gracilis nucleus 104 74
Granular layer 123, 125
Granular neurons 168
Granule cells 124, 125, 127
Gray horns, dorsal 67
Gray matter 64, 103, 123, 138
Gray rami communicantes 39
Great cerebral vein, tributaries of 226f
Great motor decussation 90
Growth releasing hormone 150
Gustatory axons
second-order 267
tertiary 267
Gustatory pathway 267, 268fc
Gustatory receptor, structure of 267f
Gut, sympathetic innervation of 44f
Gyrus 55, 159
ambiens 257
fasciolaris 196f, 199
lateral occipitotemporal 163
medial frontal 162
parahippocampal 163, 195f
rectus 162
semilunaris 257, 258
supramarginal 162
H
Habenular commissure 152, 153, 177
Habenular nucleus 8, 152
Hair cells 265
Hangman's fracture 64
Headache 230, 271
Hearing 32
end organ for 264
Heart 33, 43, 48
autonomic innervation of 49fc
sympathetic innervation of 49f
Hematoma, extradural 229, 231
Hematoxylin 16
Hemialexia 178
Hemianopia 263
Hemiataxia 146
Hemiballism 191
Hemiplegia 117, 224
alternating 117t
crossed 117
Hemispheres 120
Hemorrhage, subarachnoid 221
Hepatolenticular degeneration 193
Herpes zoster 34
Hindbrain 55
development of 5
vesicle 2
Hippocampal circuit 201
Hippocampal commissure 177, 201, 202
Hippocampal formation 198
Hippocampus 196f, 199, 200f
connections of 201, 201f
Hirschsprung's disease 45
Histamine 27
Holoprosencephaly 12
Homonymous hemianopia 146, 263
Hormone melatonin 152
Horn
bulb of posterior 178
dorsal 64
inferior 199f, 209
posterior 209
right inferior 211f
Horner's syndrome 45, 51, 96
Hydrocephalus 214
Hypogastric nerves 40
Hypogastric plexus
inferior 39, 40
superior 39
Hypoglossal nerve 89, 90, 95, 250
lesions of 250
nucleus 250f
Hypoglossal nucleus 92, 94, 96, 250
Hypokinesia 192
Hypophysis cerebri, control of 150
Hypothalamic nucleus 8, 148, 148f, 149t
clinical anatomy of 152t
Hypothalamic sulcus 137, 211
Hypothalamohypophyseal portal system 151
Hypothalamus 8, 36, 141, 147, 149, 150, 150t, 154, 224
anteroposterior subdivisions of 148f
boundaries of 147
connections of 149, 149fc
functions of 151
Hypotonia 133
I
Ideomotor apraxia, left 179
Indusium griseum 177, 198, 196f
Inferior colliculus, connections of 112, 112fc, 113f
Inferior olivary nucleus, connections of 93f
Infranuclear paralysis 246, 247f
Infundibular nucleus 148
Infundibulotuberal region 148
Infundibulum 58
Inner ear, structure of 264f
Insula 160, 162, 201
Insular lobe 160
Intercostal nerves 26
Internal capsule 9, 179, 179f, 180, 181, 189f, 226
arterial supply of 183, 184f
fibers in 183t
parts of 144, 181f, 182f
subdivisions of 181f
Internal carotid
angiogram 271f
artery 219, 219f, 220, 221, 224
Interpeduncular fossa 58, 68, 109, 147f
Intersegmental tract 79
Interspinous ligament 237
Interthalamic adhesion 137, 211
Intra-arterial digital subtraction angiography 271
Intracerebellar nucleus 123
Intralaminar nucleus 139, 143
Intralaminar thalamic nuclei, connections of 145fc
Intrauterine life 12
Intrinsic neurons 125
Iris 9, 262
Island of Reil 160
Isthmus 162, 195f
J
Joints, innervation of 29
Juxtarestiform body 248
K
Kernicterus 227
Kinetic labyrinth 265
Kinocilium 265
Kleine-Levin syndrome 152
Klumpke's paralysis 34
Kluver-Bucy syndrome 198
Krause's end bulbs 31
L
Labyrinthine artery, anterior 220
Lacrimal gland 43, 47
autonomic innervation of 48fc
innervation of 48f
Lacrimatory nucleus 245
Lactic acid 236
Lamina
cribrosa 260
internal medullary 138
terminalis 10, 162
vascular organ of 151
Language function 172f, 173
Lateral medullary syndrome 96
causes of 96f
Lateral occipital sulcus 162
Lateral spinothalamic tract, course of 72fc
Lemniscus
lesions, medial 71, 91, 96
lateral 103
Lens
accommodation of 242
increased convexity of 262
Lentiform nucleus 9, 186, 188
Leprosy 25
Lesion
sites of 263f
types of 84f
Ligamenta denticulata 62, 235
Ligamentum flavum 237
Light reflex neural pathway 262fc
Limb
anterior 180, 183, 185
posterior 180, 183, 185
Limbic lobe 160, 195
location of 195f
Limbic region, fiber bundles of 202
Limbic system 195, 204
components of 196
functions of 195
Linea splendens 62, 235
Lingual gyrus 162
Lobe 120, 159
frontal 10, 160162
middle 120
posterior 120
Locked-in syndrome 106
Locus coeruleus 205, 213, 256
Lower limb 51, 73
arteries of 52f
bilateral ataxia of 85
fibers 91
muscles of 72
Lower motor neuron 75, 75f
lesion 77t, 247f
Lumbar cistern 62, 235
Lumbar plexus 27
Lumbar puncture 62, 237, 238f
purpose of 238
Lunate sulcus 162, 166
Lung 43
autonomic innervation of 50fc
Lysosomes 16
M
Macula 265
lutea 258
structure of 266f
Magnetoencephalography 272
Mammillary bodies 8, 58
Mammillary nucleus
lateral 148
medial 148
Mammillary peduncle 149
Mammillothalamic tract 201
Martinotti cell 168
Medial dorsal nucleus 138, 141
Medial geniculate body 139, 146, 264
Medial medullary syndrome 96, 96f
Medulla 7, 88, 203, 227, 264
anterior aspect of 88
internal features of 90
oblongata 36, 56, 58, 88, 90, 90t, 91, 92, 92t, 94, 94t, 187, 217, 220, 226, 243f
blood supply of 95
development of 5, 6f
level of 95t
part of 57
posterior aspect of 89
Medullary branches 220
Medullary lamina, external 138
Medullary pyramid lesions 96
Medullary velum
inferior 7, 212
superior 7, 109, 212
Medulloblastomas 214
Megacolon 45
Meissner's corpuscles 31
Memory and behaviour, disorders of 202
Meningeal artery, middle 231
Meningeal dura, inner 229
Meninges 229
Meningioma 196
Meningocele 10f, 11, 11f
Meningomyelocele 10f, 11, 11f
Mesaxon 24
Mesencephalic flexure 3, 4f
Mesencephalic nucleus 111, 115, 244
Mesencephalon 2, 7
development of 8f
Mesostriatal dopamine system 111
Metathalamus 146
Metencephalon 7
part of 6
roof of 8f
Microcephaly 12
Microglia 19f, 20
Midbrain 7, 56, 57, 76, 109, 111, 203, 226, 227, 262
anterior aspect of 109
blood supply of 116, 116f
development of 7
external features of 109
internal features of 110
level of 115t
lower part of 112f
posterior aspect of 109
reticular formation 256
transverse section of 111f
vesicle 2
Millard-Gubler syndrome 106, 107f
Miosis 45, 96
Mitochondria 16
Mitral cells 256
Molecular layer 123, 124
Monosynaptic spinal reflex arc 80f
Monro-Kellie doctrine 233
Mossy fibers 127
Motor
aphasia 164, 172
area, primary 164, 172
end plate 29f
fibers 24, 68
homunculus 166f
neurons 44
nucleus 104, 242f, 243
sensory nucleus 103
speech area 164
Müller's muscle 45
Muscle
spindle 32
structure of 29f
stretch reflex 32, 80, 81f
tone 29, 77
Musculocutaneous nerve 26
Myasthenia gravis 29
Myelin sheath 24
formation of 24f
functions of 25
short segment of 25f
Myelination, process of 24
Myelography 270
Myenteric plexus 40, 44
Myotatic reflex 80, 81f
Myotomes 34
N
Neocerebellar lesions 133
Neocerebellum 122, 123
Neocortex 9
Neopallium 170
Neostriatum 186
Nerve 1
injuries 25
median 26
Nervous system 15, 44
classification of 15t
development of 1
divisions of 15
functions of 16
Nervus conarii 152
Neural crest cells 1, 2
derivatives of 2, 3f
Neural pathway 261fc
Neural plate 1
Neural tube 1
anomalies of 10f
defects 10
types of 10t, 11f
divisions of 2
Neural vestibular pathway 266
Neurapraxia 25
Neurilemma 22, 24
sheath 24
Neurites 16
Neurobiotaxis 102
Neuroendocrine control 205
Neuroepithelia 1
Neuroglia 16, 19, 167
capsule 126
Neuroglial cells 20
types of 19f
Neuroimaging techniques 270, 273
principles of 270
Neurological disease 270
Neuroma 25
Neuromelanin 16, 111
Neuromuscular block 30
Neuromuscular junction 29
Neurons 16, 20, 67
arrangement of 123f
classification of 18, 18fc
electron microscope structure of 17f
location of 73t
multipolar 17f, 18
nonpyramidal 168
postganglionic
parasympathetic 44
sympathetic 37
preganglionic 37, 47
propriospinal 67
pseudounipolar 18
second-order 7072, 264, 267
sympathetic
postganglionic 39
preganglionic 38, 38f, 50
tumors of 20
types of 18f
typical arrangement of 37f
Neuropil 169
Neurotmesis 25
Neurotransmitter 27, 28t
acetylcholine 41
Neurulation 1
process of 2f, 2fc
Nigrostriate fibers 189
Nissl body 16
Nissl substance 16
Nociceptors 73
Nodes of Ranvier 22, 24
Nodule 122
Noncommunicating hydrocephalus 214, 215f
Noradrenaline 27, 28
Noradrenergic system 205
Nuclear paralysis 246
Nucleus
accumbens 191, 192, 201
ambiguus 92, 9496, 248, 249, 251
anterior 148, 152
dorsolateral 139
dorsomedial 148
general 241
gracilis 91
interpositus 127
lateral 148
dorsal 139, 143
group of 143
posterior 139, 143
lumbosacral group of 68
midline 139
part of 142
posterior 148
posteromarginal 67, 72
proprius 67
special 241
suprachiasmatic 148
supraoptic 148, 152
supraspinal 94
tractus solitarius 95
Numbness 272
Nystagmus 133, 267
O
Occipital artery 231
Occipital bones, parts of 11
Occipital border, medial 158
Occipital branch, internal 224
Occipital eye field 166
Occipital gyrus
inferior 162
superior 162
Occipital lobe 10, 160, 162
functional areas of 167t
Occipital pole 158
Occipital sinus 232
Occipital sulcus, transverse 162
Occipitopontine fibers 182
Occipitotemporal sulcus 162
Oculomotor nerve 58, 242
nucleus 244f
Oculomotor nuclear complex 115
Olfactory bulb 196, 255, 256, 257f
connections of 256
Olfactory cortex
primary 258
secondary 196, 205, 258
Olfactory epithelium 255, 256, 258
Olfactory gyrus, lateral 257
Olfactory impulses 140
Olfactory nerve 196, 242, 255, 256
fibers 256
Olfactory nucleus, anterior 196, 256
Olfactory pathway 196, 255, 256f, 256fc, 257f
parts of 256fc
Olfactory receptor cells 256
Olfactory sensations 145
Olfactory stria 196, 257, 257f
Olfactory sulcus 162
Olfactory tract 196, 257, 257f
Olfactory trigone 196
Olfactory tubercle 257f
Oligodendrocyte 19f, 20
Oligodendrogliomas 20
Olivary complex, superior 102, 264
Olivary nucleus
inferior 93
superior 264
Olive 89
level of 92
Olivospinal tract 78
Operculated sulcus 159
Ophthalmic artery 220, 231
Ophthalmic nerve 47
Ophthalmoscope 263
Optic chiasma 58, 258, 260, 262
Optic disc 258
Optic nerve 9, 242, 258, 260
fibers of 259, 262
Optic pathway, version of 263fc
Optic radiation 145, 258, 260, 261
Optic recess 212
Optic tract 58, 258, 260
Orbital sulcus 162
Otic ganglia 41
Otoliths 265
Oxytocin 155
P
Pacinian corpuscles 32
Pain
burning 25, 72
control 205
inhibition, theory of 74
pathways 73
referred 33, 230
Paleo striatum 186
Paleocerebellum 122, 132
Paleopallium 170
Pallidonigral fibers 189
Pallidum 9
Papez circuit 201, 201fc
Papilledema 238
Parabrachial nucleus 196
Paracentral lobule 160, 162
Paralysis 77
effects of 246
Paramedian sulcus 120
Paraplegia 34, 85
Parasympathetic ganglia 34, 41
Parasympathetic nervous system 36, 40, 42t, 43t
Parasympathetic preganglionic neurons 48
Parasympathetic stimulation 49
Parasympathetic system 41
cranial part of 43
sacral part of 43
Paraterminal gyrus 162, 198, 258
Paraventricular nucleus 148
Paraventriculohypophyseal tracts 151f
Parietal lobe 10, 160, 162
branches to 223
functional areas of 167t
parts of 145
Parieto-occipital sulcus 159
Parkinson's disease 192, 193f
Parolfactory gyrus 162, 198
Parolivocerebellar tract 93
Parotid gland 47
autonomic innervation of 47fc
secretomotor pathway for 47f
Pars compacta 111, 191
Pars dorsalis 137
Pars opercularis 161
Pars orbitalis 161
Pars reticularis 111, 191
Pars triangularis 161
Pars ventralis 137
Pelvic splanchnic nerves 50
Periamygdaloid area 257
Pericallosal branch 222
Perilymph 265
Perineurium 22
Peripheral nerve
basic structure of 22
fibers, classification of 24
nerve fibers of 24f
Peripheral nervous system 15, 16f, 22
Peripheral neuron 255
Peripheral parasympathetic ganglia 34
Perisylvian area
left 172
right 172
Perpendicular fasciculus 177
Pes hippocampi 200
Petrous ganglion 267
Phantom limb 25
Pharyngeal artery, ascending 231
Phrenic nucleus 68
Pia mater 6, 55, 58, 62, 229, 234, 235
modifications of 234
Pigment cells 259
Pineal body 8
Pineal gland 151, 152, 152f, 155f, 177
Pineal recess 212
Pin-pricking pain 72
Piriform lobe 141, 196
Pituitary gland, posterior lobe of 8
Plain skiagraphy 270
Plantar reflex 81
Plexus 26
formation 26f
pulmonary 39
Poliomyelitis 84f, 85
Polyneuropathy 30
Polypeptides 152
Pons 7, 56, 99, 203, 226, 227
basilar part of 100
blood supply of 106, 106f
development of 6
external features of 99
internal features of 100
lower part of 101, 102f
posterior aspect of 99
tegmental part of 101
transverse section of 103t
upper part of 103, 103f
Pontine 204
branches 221
flexure 3, 4f
hemorrhage 101
nucleus 6, 100, 123, 179
reticular formation 101
Pontocerebellar fibers 101
Pontocerebellar tracts 135
Positron emission tomography 272
Postcentral gyrus 162, 248
Postcentral sulcus 162
Posterior column
medial lemniscus tract 70, 70f, 71fc
tracts, lamination of 79f
Posterolateral channels, paired 83
Postganglionic neuron 37, 41, 46, 50
Postural reflexes, impairment of 193
Posturography 133
Precommissural septum 198
Preganglionic cervicodorsal sympathectomy 51
Preganglionic parasympathetic fibers 95
Preganglionic sympathetic neurons 43, 49
Premammillary nucleus 148
Preoccipital incisure 159
Preoccipital notch 159
Preoptic nucleus 148, 152
Prepiriform cortex 258
Prepyriform 196
Presacral nerve 40
Pretectal nucleus 113
Primal cortex 170
Primary auditory pathway 264
Prolactin inhibiting hormone 150
Prolapsed intervertebral disc 64
Propriospinal tract 79
Prosencephalon 2, 8, 9
Prosody 173
Protoplasmic astrocyte 19f
Pterygopalatine ganglia 41
Ptosis 45, 96
Pudendal nerve 27
Pupil
constriction of 243, 262
dilatation of 37
innervation of 45f
Pupillary reflex 261, 261fc
pathway of 261f
Purkinje cell 18, 124, 125, 127, 133
layer 123, 125
synapses 133
Putamen 9
Pyramidal cell 18, 168
layer 169
Pyramidal decussation, level of 90, 90t
Pyramidal fibers 90, 182
Pyramidal tract 75, 75f, 88
Pyriform lobe 196
Q
Quadrangular lobule, anterior 121, 122
Quadrigeminal artery 116
Quadrigeminal brachium
inferior 109
superior 109
Quadriplegia 34, 64
Queckenstedt's sign 238
R
Rachischisis 12
Radial nerve 26
Radicular artery 82, 82f, 217
Radiography 270
Raphespinal tract 78
descending 78
Raymond syndrome 106, 107f
Raynaud's disease 51
Receptors, classification of 30
Recesses, lateral dorsal 214
Reciprocal fibers 144
Red nucleus 111, 114
connections of 114, 114f, 114fc
Reflex 133
abdominal 81
accommodation 262
pathway of 81f, 261, 262f
superficial 81, 81t
types of 80
Renal colic 51
Respiratory center 88
Reticular activating system, descending 204
Reticular formation 90, 94
afferents of 204fc
connections of 204
efferents of 204fc
functions of 205
Reticular nucleus 141, 153, 153f
Reticular pathways, descending 204
Reticular system
functional divisions of 204
inhibitory pathways of 205fc
Reticularis pontis
caudalis 101
oralis 101
Reticulospinal tract
lateral 78
medial 77, 78
Retina 9, 258
layers of 258f, 259f
visual field in 260f
Retinal quadrants 259
Retinotopy 260
Retrodorsal nucleus 68
Rhinal sulcus 163
Rhinencephalon 195
Rhombencephalon 2
Rhombic lip 7
Rhomboid cavity 88
Rhomboid fossa 212
Rods and cones 258
Romberg's sign 85, 133
Root hair plexuses 31
Rostral spinocerebellar tract 73
Rubrospinal tract 77
Ruffini's corpuscles 32
S
Sacral arteries 82
Sacral outflow 41
Sacral plexus 26, 27
Sacral sympathetic chains 39
Sacrococcygeal teratoma 12
Salivary glands 43, 46
autonomic innervation of 47fc
Salivatory nucleus
inferior 95, 248, 251
superior 105, 245, 251
Saltatory conduction 25
Satellite cells 19f, 20, 34
Scalp, dangerous area of 231
Schwann cell 19f, 20, 22, 24, 24f, 25f
sheath 24
Sciatica 64
Sclerosis, multiple 25
Secretomotor nerves 240
Segmental innervation 32
Seizures, epileptic 172
Semicircular canals 265
Semicircular duct, ampulla of 266f
Semilunar lobule
inferior 121, 122
superior 121, 122
Sensations, loss of 224
Sense organs 204
Sensory
areas 166, 170
ataxia 133
cerebral cortex 255
cortex 164
decussation, level of 91, 92f, 92t
experiences 145
fibers 50, 68
homunculus 166f
information 15
input 16
modalities 195
neuron disease 85
nucleus 242f, 244
principal 7, 103
speech area 166, 172
tract 69f
Septal region 198
Septum pellucidum 208
Serotonin 27, 28
Serotoninergic raphe system 204
Sexual activity and reproduction, regulation of 151
Short ciliary nerves 262
Single cerebellar folium 124f
Sinuatrial node 48
Sinus
confluence of 231
dural venous 229, 231, 232t
intercavernous 232
left transverse 232
straight 232
superior sagittal 231
transverse 232
Skeletal muscle 29, 29f
innervation of 27
Skin 43, 237
Skull
bone 55
injuries to 238
Slurred speech 271
Smell 32
Sneezing 88
Soft palate 267
Solitariothalamic tract 143, 251
Solitary tract 43, 94
nucleus of 92, 245, 248, 249, 251, 268f
Somatic efferent 240, 241, 244
fibers 243
Somatic nucleus 241
Somatic sensory
cortex 167
fibers 186
Somatomotor control 205
Somatomotor fibers 240
Somatosensory area
primary 165, 172
second 165
Somatosensory association area 166
Somatotopic lamination 78
Special cell organelles 17t
Special senses 255
pathways of 255
Special sensory afferent 240, 242
Special somatic afferent 104, 241, 255
fibers 246
Special visceral afferent 241, 242, 247, 249, 251, 255
fibers 245
Special visceral efferent 104, 240, 241, 245, 247, 249, 251
fibers 243
Speech
difficulty in 193
disturbances, types of 171
Sphincter pupillae muscle 45, 262
Spina bifida 11, 11f, 12
cystica 11
occulta 11
Spinal accessory
nerve 249
nucleus 68
Spinal artery 82f
anterior 217, 218, 220
medullary branches of anterior 96f
posterior 81, 217, 220
thrombosis of anterior 83f
Spinal cord 1, 15, 22, 23f, 36, 56, 57f, 60, 61f, 64f, 75f, 77, 83t, 89, 131, 142, 168, 187, 204, 218, 218f
blood supply of 81, 217, 218f
central canal of 20
descending tracts of 78t
development of 4, 5f, 6fc
external features of 62, 63f
functions of 61
internal structure of 65
intrinsic arterial supply of 82f
lesions of 83
level of 32, 65f
lower end of 61f
microscopic structure of 66
recession of 62f
segments of 57f
tracts in 68
transection of 85
transverse section of 65, 65f, 66f, 69f
venous drainage of 83f, 219f
Spinal epidural space 235
Spinal ganglia 34
Spinal gray columns 68t
Spinal lemniscus 72
Spinal medulla 60
Spinal meninges 61, 62f, 235
Spinal nerves 15, 22, 27, 39, 62f, 82
emergence of 23f
exit of 63
ventral rami of 26f
Spinal nucleus 101, 246, 249
Spinal reflex 80
arc 81f
intersegmental 79
Spinal segments 63, 64t, 81t
concept of 63f
vertebral levels of 63
Spinal trigeminal nucleus 96
Spinocerebellar tract 131
anterior 73, 74
posterior 72, 130
Spino-olivary tract 73, 74
Spinoreticular tract 7274
Spinospinal tracts 79
Spinotectal tract 73, 74
Spinothalamic pathways 70f
Spinothalamic tract 68, 96
anterior 70f, 73, 74
anterolateral 71
formation of lateral 72fc
lamination of 79f
lateral 70f, 73, 74
Spiral ganglion 264
Splenial gyrus 199
Splenium 177
Split brain syndrome 178
Spondylolisthesis 64
Static labyrinth 265
Stellate cells 18, 124, 125, 128, 168
Stellate ganglion 39
Stellate neurons 168
Stereocilia 265
Stereoscopic vision 259
Stress 151
Stretch reflex 29, 81t
Stria habenularis 138, 152
Stria medullaris 90, 92, 212
fibers of 130
thalami 138, 152
Stria terminalis 138, 180, 202
Striate arteries 222
Striate cortex 166
Stroke 224
hemiplegic 250
syndrome 183
Subarachnoid cistern 234, 234f, 234t
Subarachnoid space 58, 229, 233
Subdural hematoma 230
Subdural space 58, 229, 230
Subfalcine herniation 230
Subfornical organ 151
Sublingual salivary glands 46, 46f
Submandibular ganglia 41
Submandibular salivary glands 46, 46f
Submucosal plexus 40, 44
Substantia gelatinosa 67, 90
Substantia nigra 110, 111, 117, 187, 190
connections of 111, 191
neurons of 16
Subthalamic fasciculus 154, 189, 191
connections of 191f
Subthalamic nucleus 154, 187, 191
Subthalamic region 191
Subthalamus 8, 153
Suditory area 167f
Sulcal branches 82
Sulcus 159
anterolateral 89
basilaris 99
limitans 5, 90, 213, 241
median 213
posterior median 62, 89, 90
posterolateral 90
Supracommissural septum 198
Supranuclear lesion, effect of 249, 250
Supranuclear paralysis 246
Supraopticohypophyseal tracts 151f
Suprapineal recess 212
Supraspinous ligament 237
Swallowing 88
Sympathetic chain 39
Sympathetic ganglia 34, 49
Sympathetic nerves 48, 49f
Sympathetic nervous system 36, 38, 40f, 42t, 43, 43t
Sympathetic systems 41
Sympathetic tract, descending 96
Sympathetic trunk, location of 39
Synapses 27
classification of 27
types of 28f
Synaptic cleft 27
Synaptic knob 27
Synaptic vesicles 29
Synergia 133
Syringomyelia 84f, 85
T
Tactile agnosia 171, 172
Tactile anomia 179
Taenia thalami 138
Tapetum 178, 209
Taste 32, 251fc
sensations 95
Tectospinal tract 77, 78
Tectum 110, 111
Tegmentum 111
Tela choroidea 138, 208, 208f, 212f, 213, 234
Telencephalic flexure 4
Telencephalic vesicles 2
Telencephalon 2, 8, 9
Temporal gyrus
anterior transverse 167f
inferior 162
middle 162
posterior transverse 167f
superior 162
Temporal lobe 10, 160, 161
branches to 223
epilepsy 201
functional areas of 168t
parts of 144, 145
Temporal operculum 162
Temporal pole 158
Temporo-occipital branch 224
Tentorial surface 162
Tentorium cerebelli 119, 229, 230
Thalamic fasciculus 154, 189
Thalamic nucleus 139, 143f
anterior group of 141, 145fc
lateral group of 144fc
medial group of 141
subdivisions of 141fc
ventral group of 142
Thalamic peduncles 141
Thalamic radiation 143f, 144
anterior 144
inferior 181, 145
posterior 145
superior 143, 145
Thalamoperforators 222
Thalamostriate vein 138, 188
Thalamus 8, 71, 137, 187, 189f, 226
connections of 140, 142f
dorsal 137
functions of 145
horizontal section of 139f
internal structure of 138
lateral part of 141
medial dorsal nucleus of 145fc
midline nucleus of 145fc
nucleus of 140f, 141t
parts of 141
relations of 139f
superimposition of 139f
ventral lateral nuclei of 144fc
Third-order neurons 70, 264, 267
Thoracic nerves 26, 27
Thoracic nucleus, posterior 67
Thoracic sympathetic chain 39
Thoracolumbar outflow 37f, 38, 42
Thorax 40f
Thromboangiitis obliterans 52
Thyrotropin releasing hormone 150
Tissues constituting nervous system 16
Tongue
one-third of 267
two-thirds of 267
Tonotopic arrangement 264
Tonsillar herniation 230
Torcular herophili 231
Tract of Lissauer 85
Tractus solitarius 94, 251
Transcranial Doppler ultrasonography 272
Transverse temporal gyrus 167
anterior 264
posterior 264
Trapezoid body 100102, 264
nucleus of 264
Tremor 192
Trigeminal lemniscus 103, 251
Trigeminal nerve 7, 99, 103, 111, 115, 128, 243, 245f, 246, 249, 251
divisions of 230
motor nucleus of 103
nucleus 104
ophthalmic division of 230
sensory nucleus of 104
spinal nucleus of 90, 95, 251
Trigeminal tract, dorsal 104, 105fc
Trochlear muscles 115
Trochlear nerve 243
nucleus 245f
Trochlear nucleus 111, 115, 243
Truncal ataxia 133
Tuber cinereum 58
Tuberal nucleus, lateral 148
Tuberculum cinereum 90
Tuberomammillary nucleus 148
Tumors 214
Tunnel vision 263
Typical spinal nerve 25, 26f
Typical synapse, structure of 27f
U
Ulnar nerve 26
Uncinate fasciculus 176
Uncinate fits 258
Uncus 163
Unilateral anterior cerebral artery 171
Unipolar neurons 18
Upper limb 51
arteries of 52f
fibers 91
Upper motor neuron 75
effects of 247f
lesion 77t
position of 75f
Upper six cervical vertebrae 220
Upper thoracic sympathetic ganglia 51
Upper three cervical nerves 230
Upper vertebral body 64
Urea 236
Ureter 51
Urinary bladder 43, 49
autonomic innervation of 51fc
innervation of 50f
Uvula 121, 122
V
Vagal nucleus, dorsal 92, 94
Vagus nerve 90, 95, 249f, 251
nucleus 94, 249f
Vasocorona 217
Venous drainage 83, 116, 219, 226
Venous sinus 230, 230f
anteroinferior dural 232f
posterosuperior 231f
thrombosis 231
Venous vasocorona 83, 219
Ventral anterior nucleus 139, 142
Ventral cochlear nucleus 89
Ventral gray columns 90
Ventral horn 5, 64
Ventral intermediate nucleus 139
Ventral lateral nucleus 139, 142
Ventral pallidum 187, 191
Ventral posterior nucleus 139, 142
Ventral posterolateral nucleus 71, 139
Ventral posteromedial nucleus 251
Ventral striatum 187, 191, 192f
Ventral tegmental decussation 113
Ventral thalamic region 154f
Ventral thalamus 153
Ventral trigeminothalamic tract 104
Ventricular system 3f, 207f
development of 4
Ventrolateral nucleus 68
Ventromedial nucleus 148
Ventroposterior nucleus 248
Vermis 7, 120
syndrome 133
Vertebral angiogram 270, 271f
Vertebral artery 219f
branches of 221f
Vertebral bodies 63
Vertebral canal 60
Vertebral levels 64t
Vertebral venous plexus, internal 83, 219
Vertebrobasilar arteries 220
Vertigo 267
Vesical plexus 40, 50
Vestibular apparatus 266f
Vestibular ganglia 105
Vestibular labyrinth 264
Vestibular nuclear complex 105f
Vestibular nucleus 94, 105, 127, 128, 246, 248
connections of 246, 248f
Vestibular pathway, disorders in 267
Vestibulocerebellar fibers 127, 130
Vestibulocochlear cranial nerve 56
Vestibulocochlear nerve 246
nuclei of 104, 105
Vestibulospinal tract
lateral 78, 79
medial 78, 248
Virchow-Robin space 234, 235f
Viscera, abdominal 94, 95
Visceral afferent fibers 16, 24
Visceral efferent fibers 24
Visceral nucleus 241
Visceral sensory fibers 240
Visceromotor fibers 240
Viscous saliva 47
Vision 32
blurred 271
double 25, 271
field of 259
neural pathway for 262
Visual agnosia 172
Visual area 166
effects of damage to 166
Visual cortex 260, 260f, 261f
primary 262
Visual field 259
peripheral parts of 260f
Visual pathway 258, 258f, 263f
lesions of 263
Visual reflex 117, 261
Vomiting 88
W
Wallenberg syndrome 96
Watershed infarcts 82, 218
Weakness 272
Weber syndrome 116, 116f
Wernicke lies 166
White matter 64, 68, 103, 127, 138, 158f
White rami carry fibers 39
Wilson's disease 193
Word deafness 172
Z
Zona incerta 153, 191
Zygomaticotemporal nerve 47
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Chapter Notes

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Development of Nervous SystemCHAPTER 1

 
INTRODUCTION
The development of central nervous system begins in the third week of intrauterine life with the formation of neural plate in the midline central part of ectoderm. This specialized plate is neuroectodermal in origin and it develops into a tubular form in a process called neurulation. The whole of the central nervous system (i.e., brain and spinal cord) and the peripheral nervous system (i.e., nerves and ganglia) are derived from this neural tube. The differentiated neuroectodermal (or neuroepithelia) cells further differentiate into neuroblast and glioblast cells; with further growth, neuroblast cells form neurons which are the basic functional unit of the nervous system. The glioblast cells differentiate to form oligodendrocytes and astrocytes which are supporting cells of the nervous system.
 
NEURULATION (AN 79.3)
The process of formation of neural plate, neural folds, and neural tube is called neurulation (Figures 1.1A to D).
The formation of neural plate starts as a thickened ectodermal area in its central part, just above the notochord. The notochord induces the thickening of ectoderm to form neural plate.
  • ❖ With the increase in length of embryonic disc, the neural plate also elongates and the central part becomes depressed to form the neural groove.
  • ❖ The neural groove further deepens and changes into neural tube. The neural tube is open at both ends as the cranial (anterior) and caudal (posterior) neuropores.
  • ❖ The neural tube now gets separated from the ectodermal layer and lies just beneath it. The cells at the lateral margins of neural plate also separate and are located in between ectoderm and neural tube. These are also neuroectodermal cells and are known as neural crest cells.
  • ❖ On the 25th day, the cranial neuropore is completely closed and this is soon followed by closure of caudal neuropore on the 27th day.
  • ❖ The neural tube undergoes many changes to form spinal cord and brain while neural crest cells form all the neural 2elements outside the central nervous system (Figures 1.1A to D and Flowchart 1.1).
  • ❖ The lumen of the neural tube gives rise to the ventricular system of the brain and central canal of the spinal cord.
zoom view
Figures 1.1A to D: Process of neurulation.
zoom view
Flowchart 1.1: Process of neurulation.
 
NEURAL CREST
  • ❖ The neural crest arises as a strip of differentiated neuroectodermal cells located on the lateral margins of neural plate. With the closure of neural tube, the neural crest cells of each side appear as a group of isolated cells on the dorsal aspect of neural tube, separated from ectoderm and neural tube.
  • ❖ The neural crest cells further descend downward and laterally and divide into several smaller groups. These groups differentiate into a wide variety of cells and structures and migrate to distant places throughout the body.
  • ❖ In subsequent development, several important structures are derived from the neural crest which include sensory and autonomic ganglia, Schwann cells, and meninges of the brain. A list of all derivatives of neural crest are given in the following text (Figure 1.2).
 
Derivatives of Neural Crest
  • ❖ Dorsal root ganglion neurons
  • ❖ Neurons of sensory ganglions of cranial nerves 5, 7, 9, and 10
  • ❖ Neurons of sympathetic ganglia
  • ❖ Schwann cells
  • ❖ Cells of adrenal medulla
  • ❖ Chromaffin tissue in carotid and para-aortic bodies
  • ❖ Melanoblasts
  • ❖ Leptomeninges (pia and arachnoid)
  • ❖ Odontoblasts and mesenchyme of dental papilla
  • ❖ Mesoderm of head region
  • ❖ Cells of the diffuse endocrine system
 
Divisions of Neural Tube
Along with cellular differentiation, the neural tube increases in length. The cranial part shows three rounded enlargements while the caudal part remains tubular. The three enlargements form the forebrain, midbrain, and hindbrain. The tubular part forms the spinal cord.
 
DEVELOPMENT OF BRAIN (AN 64.2)
The brain develops from the enlarged cranial part of the neural tube. At about the end of the fourth week, the cavity of the developing brain shows three dilatations. Craniocaudally, these are the prosencephalon (forebrain vesicle), mesencephalon (midbrain vesicle), and rhombencephalon (hindbrain vesicle). The prosencephalon becomes subdivided into the telencephalon and the diencephalon. The telencephalon consists of right and left telencephalic vesicles. 3The rhombencephalon also becomes subdivided into a cranial part, the metencephalon, and a caudal part, the myelencephalon. The parts of the brain that are developed from each of these divisions of the neural tube are shown in Figures 1.3A to D and Flowchart 1.2.
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Figure 1.2: Derivatives of neural crest cells.
 
FLEXURES OF BRAIN
The prosencephalon, mesencephalon, and rhombencephalon are at first arranged craniocaudally (Figure 1.4A). Their relative position is greatly altered by the appearance of a number of flexures. These are as follows:
  • ❖ The cervical flexure, at the junction of the rhombencephalon and the spinal cord (Figure 1.4B)
  • ❖ The mesencephalic flexure (or cephalic flexure) in the region of the midbrain (Figure 1.4C)
  • ❖ The pontine flexure, at the middle of the rhombencephalon, dividing it into metencephalon and myelencephalon (Figure 1.4D)
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    Figures 1.3A to D: Stages in the development of brain vesicles and the ventricular system.
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    Flowchart 1.2: Development of various parts of brain.
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    Figures 1.4A to D: (A) Neural tube before formation of flexures; (B) Cervical flexure; (C) Mesencephalic flexure; (D) Pontine flexure.
  • ❖ The telencephalic flexure that occurs much later between the telencephalon and the diencephalon
These flexures lead to the orientation of the various parts of the brain as in the adult.
 
DEVELOPMENT OF THE VENTRICULAR SYSTEM
Each of the subdivisions of the developing brain encloses a part of the original cavity of the neural tube (Figure 1.5).
  • ❖ The cavity of each telencephalic vesicle becomes the lateral ventricle.
  • ❖ The cavity of diencephalon (along with the central part of the telencephalon) becomes the third ventricle.
  • ❖ The cavity of mesencephalon remains narrow and forms the cerebral aqueduct (aqueduct of Sylvius).
  • ❖ The cavity of rhombencephalon forms the fourth ventricle. Its continuation in the spinal cord is the central canal.
A brief outline of the development of different parts of the central nervous system is given in the following text.
 
Development of Spinal Cord (Figures 1.6A and B; Flowchart 1.3)
The spinal cord develops from the caudal tubular part of the neural tube.
  • ❖ The hollow cavity of the tube remains narrow and is lined by a single layer of ependymal cells. The cavity is now called the central canal.5
  • ❖ Outside the central canal, the neuroblast cells collect to form a distinct layer or zone. This is called a mantle layer/zone initially and it further forms the spinal gray matter.
  • ❖ Outer to the mantle layer, the processes (axons) of neuroblast cells form another layer, the marginal layer/zone which forms the spinal white matter.
  • ❖ The walls of the neural tube change gradually. The dorsal and ventral walls remain thin and are now called roof and floor plates, respectively.
  • ❖ The lateral walls are demarcated into dorsal and ventral regions by the appearance of an inner longitudinal sulcus called sulcus limitans.
  • ❖ The cells of the dorsal region are sensory neuroblasts and are known as alar lamina which is functionally afferent or sensory in nature. It receives axons from dorsal root ganglia which become the dorsal root of the spinal nerve. The alar lamina becomes the dorsal horn of the spinal cord.
  • ❖ The cells of basal lamina (ventral region) are efferent/motor in nature. Their axons exit the spinal cord to form the ventral root of spinal nerves. The basal lamina becomes the ventral horn of spinal cord.
  • ❖ Myelination of the nerve fibers in the spinal cord begins during the fourth month of the intrauterine life and continues till late after birth.
  • ❖ The development of bony vertebral canal begins almost at the same time and continues till the eighth week and the spinal cord extends up to the same length. However, after that period, there is a rapid growth of vertebral canal and the levels of spinal cord lag behind. At birth, the conus medullaris extends only up to the level of third lumbar vertebra (L3) which further ascends to the level between L1 and L2 in adults.
  • ❖ The lower segment of the vertebral canal contains the lower lumbar, sacral, and coccygeal spinal nerves in a bundle called cauda equina. It also contains the extensions of pia mater, filum terminale, which anchor the spinal cord to coccyx.
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Figure 1.5: Development of ventricles of the brain.
 
Development of Hind Brain
 
Development of Medulla Oblongata (Figure 1.7 and Table 1.1)
  • ❖ It develops from myelencephalon which is derived from rhombencephalon (hind brain) part of the neural tube. The sulcus limitans divides the lateral walls into sensory alar lamina and ventral basal lamina.
  • The sensory neuroblasts of alar lamina form the following nuclei in medulla oblongata:
    • ➢ Spinal nucleus of trigeminal nucleus
    • ➢ Nucleus of tractus solitarius
    • ➢ Gracile and cuneate nuclei
    • ➢ Inferior olivary nuclear complex
    • ➢ Cochlear nuclei
    • ➢ Vestibular nuclei
  • The motor neuroblasts of basal lamina form the following nuclei:
    • ➢ Dorsal nucleus of vagus nerve
    • ➢ Nucleus ambiguus
    • ➢ Hypoglossal nucleus
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      Figures 1.6A and B: Stages of development of spinal cord: (A) Formation of alar lamina and basal lamina; (B) Differentiation of ventral, dorsal, and intermediate horns.
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      Flowchart 1.3: Development of spinal cord (SC).
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      Figure 1.7: Different stages of development of medulla oblongata. Arrows show migration of cells of alar plate to the olivary nuclear complex.
  • ❖ The roof plate of the cranial part of medulla widens to form roof of the 4th ventricle. It is a single layer of ependymal cells.
  • ❖ A double-layered pia mater along with a blood vessel invaginates the cavity of the fourth ventricle. The blood vessel proliferates into tuft of capillaries. This whole structure, i.e., (i) ependyma, (ii) pia mater, and (iii) capillaries, together form the choroid plexus. The choroid plexus produces cerebrospinal fluid (CSF).
 
Development of Pons (Figure 1.8 and Table 1.1)
Pons develops from the ventromedial part of metencephalon which is derived from rhombencephalon.
  • ❖ Pontine flexure separates pons from the medulla oblongata at the pontomedullary junction.
  • ❖ The sensory neuroblasts of alar lamina form pontine nuclei in the basilar part of pons. Axons of pontine nuclei form middle cerebellar peduncle which connects pons to cerebellum.7
    TABLE 1.1   Derivatives of alar and basal laminae in brainstem (*develop from both laminae).
    From alar lamina
    From basal lamina
    Midbrain
    • Superior and inferior colliculi
    • Mesencephalic nucleus of trigeminal nerve
    • Substantia nigra
    • Red nucleus
    • Oculomotor nucleus
    • Edinger–Westphal nucleus
    • Trochlear nucleus
    • Substantia nigra*
    • Red nucleus*
    Pons
    • Pontine nuclei
    • Vestibular nuclei
    • Cochlear nuclei
    • Main sensory nucleus of trigeminal nerve
    • Nucleus of spinal tract of trigeminal nerve
    • Nucleus of tractus solitarius
    • Motor nucleus of trigeminal nerve
    • Motor nucleus of facial nerve
    • Abducent nucleus
    • Superior salivatory nucleus
    • Lacrimatory nucleus
    Medulla
    • Inferior olivary nucleus
    • Vestibular nucleus
    • Nucleus of spinal tract of trigeminal nerve
    • Nucleus of tractus solitarius
    • Part of dorsal nucleus of vagus nerve
    • Part of dorsal nucleus of vagus nerve
    • Inferior salivatory nucleus
    • Nucleus ambiguus
    • Hypoglossal nucleus
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    Figure 1.8: Development of metencephalon.
    The alar lamina also contributes to the formation of (i) nucleus tractus solitarius, (ii) nucleus of spinal tract of trigeminal nerve, and (iii) vestibular and cochlear nuclei.
    The alar lamina also forms the principal sensory nucleus of trigeminal nerve.
  • ❖ The basal lamina of pons differentiates into the following nuclear groups:
    • ➢ Abducent nucleus
    • ➢ Motor nucleus of trigeminal nerve
    • ➢ Motor nucleus of facial nerve
    • ➢ Superior salivatory nucleus
    • ➢ Lacrimatory nucleus
 
Development of Cerebellum (Figure 1.9)
  • ❖ The cerebellum is derived from the dorsolateral part of metencephalon. The alar laminae thicken to form rhombic lip.
  • ❖ The rhombic lips produce bulging that fuse in midline to form cerebellar plate.
  • ❖ The cerebellar plate separates into cranial and caudal parts; the cranial part forms the vermis and cerebellar hemispheres and the caudal part is separated as the flocculonodular lobe.
  • ❖ The mantle neuronal layer of the original neural tube differentiates into cerebellar nuclei and layers of cerebellar cortex.
  • ❖ The part of the roof plate of the fourth ventricle forms superior and inferior medullary velum.
 
Development of Midbrain (Figure 1.10 and Table 1.1)
The midbrain develops from mesencephalon which is the smaller middle dilatation of the neural tube.
  • ❖ The dorsal alar lamina of the mantle layer differentiates into:
    • ➢ Superior colliculi
    • ➢ Inferior colliculi
    • ➢ Pretectal nucleus
    • ➢ Mesencephalic nucleus of trigeminal nerve8
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      Figure 1.9: Development of cerebellum from the roof of the metencephalon.
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      Figure 1.10: Different stages of development of mesencephalon.
      The superior and inferior colliculi carry the special sensory fibers and act as reflex centers for light and hearing, respectively.
  • ❖ The basal lamina differentiates into:
    • ➢ Tegmentum of midbrain
    • ➢ Substantia nigra
    • ➢ Oculomotor nucleus
    • ➢ Edinger–Westphal nucleus
    • ➢ Trochlear nucleus
    • ➢ Red nucleus
The origins of red nucleus, substantia nigra, and reticular nuclei are probably mixed from neuroblasts of alar and basal laminae.
The cavity of the mesencephalon forms cerebral aqueduct which remains narrow and is continuous above with the third ventricle and below with the fourth ventricle.
Most of the descending fibers (corticospinal, corticopontine, and corticobulbar) pass through the ventral part of midbrain, and a thick bundle of fibers is formed which is known as crus cerebri.
 
Development of Diencephalon
  • ❖ Diencephalon develops from the prosencephalon which gets divided into telencephalon and diencephalon.
  • ❖ The cavity of diencephalon is the third ventricle which is single and is present in a median plane.
  • ❖ The diencephalon gives rise to the epithalamus, thalamus, subthalamus, and hypothalamus.
  • ❖ The epithalamus develops from the embryonic roof plate and alar lamina. It gives rise to the pineal body, habenular nuclei, habenular commissure, and posterior commissure.
  • ❖ The thalamus also develops from the alar lamina; therefore, it becomes the main sensory relay station. The neurons proliferate and form various nuclei of thalamus including medial and lateral geniculate bodies.
  • ❖ The hypothalamus develops from the alar plate and floor plate below the hypothalamic sulcus. It forms the hypothalamic nuclei, mammillary bodies, and posterior lobe of pituitary gland.9
  • ❖ The other derivatives of diencephalon include optic vesicle, cup, and stalk. They give rise to the retina, iris, ciliary body, and optic nerve.
 
Development of Corpus Striatum
  • ❖ The corpus striatum appears in the sixth week of intrauterine life. The developing telencephalon can be divided into a thick basal portion, which is called striatal part, and a cranial part, called pallidum. The striatal part develops into corpus striatum while the pallidum gives rise to the cerebral cortex.
  • ❖ The striatal part appears as a prominent swelling in the floor of the cerebral hemispheres. The swelling is due to proliferation of germinal cells. The elevation gets divided into medial and lateral regions. As the lateral ventricle expands in the developing cerebral lobes, the striatal part bulges into the floor of the main part of ventricular cavity and in the roof of the inferior horn. The axons arising from the medial and lateral regions of striatum pass to the cerebral cortex and form the internal capsule. These developing fibers separate the lateral part from ventricular cavity, thereby incompletely dividing the medial and lateral elevations. The medial elevation is now called caudate nucleus, which comes to lie in the floor of the anterior horn and central part of the lateral ventricle and in the roof of its inferior horn. The lateral elevation is known as lentiform nucleus, which is further divided into a large putamen and a medial globus pallidus.
  • ❖ As the diencephalon is situated medial to the expanding cerebral hemispheres, the location of corpus striatum is lateral to the developing thalamus. Thus, the caudate nucleus comes into direct contact with the thalamus, but the lentiform nucleus remains separated from it by fibers of the internal capsule.
  • ❖ Some fibers from the corpus striatum pass lateral to the lentiform nucleus. They constitute the external capsule.
 
Development of Cerebrum (Figure 1.11)
  • ❖ The cerebral hemispheres develop from telencephalon which is derived from prosencephalon. The telencephalon is subdivided into a thick basal part and a thin superior part.
  • ❖ The two lateral evaginations appear around the cranial-most part of the neural tube. These evaginations form the cerebral hemispheres, connected to each other with commissural fibers, the corpus callosum.
  • ❖ The cavity of prosencephalon forms lateral ventricles that communicate with the third ventricle through the interventricular foramen.
  • Cerebral cortex: It is formed by the neuroblasts formed by the thick basal part of telencephalon. These neuroblasts proliferate rapidly and form the cerebral cortex which is classified as the neocortex and the allocortex. The allocortex is a three-layered cortex which represents 10% of the total cerebral cortex. The neocortex is a well-differentiated, six-layered cortex which is present in 90% of the total cerebral cortex.
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    Figure 1.11: Development of cerebral hemisphere and diencephalon (I, II, III, and IV are lateral views of developing cerebrum and V, VI, VII, and VIII are coronal sections).
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  • ❖ The cerebral cortex grows in various directions to form various lobes. The ventral expansion of cortex forms the frontal lobe, the dorsal expansion forms the occipital lobe, the lateral expansion forms the parietal lobe, and the inferior expansion forms the temporal lobe.
  • ❖ As growth proceeds, the cortex develops the deep fissures by dipping down and form convolutions. Gradually, by the end of pregnancy, a complex pattern of sulci (fissures) and gyri (elevations) develops.
  • ❖ As the cortex is expanding to form various lobes, the ventricular cavity is also pulled along resulting in the formation of three horns of lateral ventricle: Anterior, posterior, and inferior horns in frontal, occipital, and temporal lobes, respectively.
  • ❖ The layer beneath the cortex contains the axons of growing neurons and becomes devoid of cell bodies. This develops into white matter of the cerebral hemispheres.
  • ❖ The roof of the neural tube that closes the cranial end of prosencephalon is called the lamina terminalis. The fibers pass through this to go from one hemisphere to the other. These fibers form the commissures. The first commissure to develop is anterior commissure, followed by hippocampal commissure. The corpus callosum, the largest commissure, appears later.
 
NEURAL TUBE DEFECTS (AN 64.3 AND 79.5)
Neural tube defects (NTDs) are the common congenital malformations of the central nervous system. Nonclosure of neural folds in the 3rd or 4th week of development results in NTDs. The factors behind the abnormal closure of neural tube can be:
  • ❖ Increased age
  • ❖ Folic acid deficiency
  • ❖ Intake of teratogenic drugs
The resulting malformations may include the faulty development of overlying skin, muscles, vertebrae, skull bones, and meninges. Table 1.2 shows the common congenital malformations and their causation (Figures 1.12A to E).
  1. Anencephaly (an—without + enkephalos—brain):
    • ➢ Anencephaly occurs due to failure of closure of cranial neuropore (rostral end of neural tube) in the third to fourth week of gestation, approximately at 18–20 somite stage. This type of NTD is incompatible with life. It occurs in 1/5,000 births. It is twice more common in females than in males. Anencephaly has multifactorial inheritance (Figure 1.13A).
      Table 1.2   Various types of neural tube defects.
      Nonclosure of cranial neuropore
      Nonclosure of caudal neuropore
      Chromosomal disorders
      Other congenital malformations
      Anencephaly
      Spina bifida occulta
      Holoprosencephaly
      Arnold–Chiari malformation
      Encephalocele
      Spina bifida cystica:
      • With meningocele
      • With meningomyelocele
      • With rachischisis
      Microcephaly
      Dandy–Walker malformation
      Sacrococcygeal teratomas
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      Figures 1.12A to E: Anomalies of the neural tube: (A) Craniorachischisis; (B to D) Varieties of meningomyelocele; (E) Meningocele.
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    • ➢ In anencephaly, as the influence of the expanding brain is removed, secondary adaptive alterations occur in the cranial base, so squamous parts of occipital bones remain underdeveloped. It results in a major portion of brain, skull, and scalp being absent though the brainstem is intact. Although eyes are present, optic nerves are absent.
    • ➢ Anencephalic fetuses lack a swallowing reflex. The last 2 months of pregnancy are characterized by polyhydramnios.
  2. Encephalocele: It is a NTD characterized by protrusion or projection of parts of brain and membranes that cover it through defects in the skull. The portion of brain that sticks out is usually covered by skin or a thin membrane so the defect looks like a small sac (cystic swelling). It most often affects the back of skull (occipital bones). The defect is caused by failure of the neural tube to close completely during fetal development (Figure 1.13B).
  3. Spina bifida is a NTD which affects the spinal region. It consists of splitting of vertebral arches and may or may not involve the underlying neural tissue. It is further of two types: (i) Spina bifida occulta and (ii) Spina bifida cystica.
    1. Spina bifida occulta: It is often called hidden spina bifida as the spinal cord and the nerves are usually normal and there is no opening on the back. It is evidenced by a tuft of hair in the lumbosacral region. It is the mildest and most common form of NTD in which one or more vertebrae are malformed. This variation occurs due to lack of fusion of vertebral arches in 10% of the population. The defect in vertebral arches is covered by skin and does not involve the neural tissue. There is no disturbance of spinal function. Most people are unaware of this anomaly unless it is discovered on an X-ray performed for an unrelated reason.
    2. Spina bifida cystica: A bony defect in the vertebral column causes a cleft in that column. The meninges covering the spinal cord and part of spinal cord protrude through the cleft and are clearly visible. This malformation includes meningocele and meningomyelocele.
      • Spina bifida with meningocele: This NTD occurs when bones do not close around the spinal cord and meninges are pushed out through the vertebral defect causing a fluid-filled (CSF) sac to form. The spinal cord and the nerves remain in normal position. The sac is covered by skin and may require surgery (Figure 1.13C).
      • Spina bifida with meningomyelocele: Meningomyelocele is the most common type and accounts for 75% of all spina bifida cases. In this condition, a portion of the spinal cord protrudes through the vertebral defect. In some cases, sacs are covered by skin, but in other cases tissues and nerves may be exposed.
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        Figures 1.13A to E: Types of neural tube defects: (A) Anencephaly; (B) Encephalocele; (C) Spina bifida with meningocele in thoracic region; (D) Spina bifida with meningomyelocele; (E) Craniorachischisis.
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        The extent of disabilities is related to the location of the spinal cord defect (Figure 1.13D).
      • Spina bifida with rachischisis (rachis—spine and schisis—split): It is the most severe form of spina bifida. In this, the posterior neuropore or neural tube fails to fuse by the 27th day or the fourth week of intrauterine life (IUL). As a consequence, the vertebrae overlying the spinal cord do not fuse leaving the spinal cord open causing paralysis from the level of defect caudally. This variation presents clinically as an open NTD on the surface of back.
      • Craniorachischisis is associated with simultaneous anencephaly and complete rachischisis. Affected pregnancy results in miscarriage or stillbirth (Figure 1.13E).
  4. Holoprosencephaly (HPE) is a chromosomal disorder which can be present in trisomy 13 or trisomy 18. There is partial or complete failure of development of midline structures, resulting in malformations of the brain and face. In brain, the lateral ventricles fuse into a single telencephalic vesicle. On face, the eyes and nasal cavities are fused and are present in midline.
  5. Microcephaly: In this anomaly, the cranial vault is smaller in size than normal. It results in an underdeveloped brain causing gross mental retardation. It is an autosomal recessive disorder or may be produced due to antenatal cytomegalovirus infection or exposure to radiation.
  6. Arnold–Chiari malformation occurs when the caudal vermis along with the tonsils of the cerebellum and the medulla oblongata have herniated through the foramen magnum. Clinical signs are caused by compression of the medulla oblongata and stretching of CN IX, CN X, and CN XII which include spastic dysphonia, difficulty in swallowing, laryngeal stridor (vibrating sound heard during respiration as a result of obstructed airways), diminished gag reflex, apnea, and vocal cords paralysis (Figure 1.14).
  7. Dandy–Walker malformation: In this syndrome, atresia of foramina is present in the roof of the fourth ventricle (that communicates with the subarachnoid space) which results in dilation of the fourth ventricle and agenesis of cerebellum.
  8. Sacrococcygeal teratoma: This is the most common germ cells tumor in newborns with a frequency of 1 in 30,000–70,000 live births. The female–male ratio is 4.1. Germ cells are the cells that develop in the embryo and later on become the cells of the reproductive system. Most germ cell tumors occur in the testis and ovaries, but few of these pleuripotent germ cells proliferate and form tumors near the tail bone such as sacrococcygeal teratoma. The remnants of primitive streak persist in the sacrococcygeal region as primitive cells give rise to cells of three major tissue layers, i.e., ectoderm, mesoderm, and endoderm. Therefore, sacrococcygeal teratomas contain both mature tissues such as teeth and bone and immature tissues resembling embryonic tissue.
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Figure 1.14: Arnold–Chiari syndrome.
MULTIPLE CHOICE QUESTIONS
Q1. All of the following are derivatives of neural crest cells, except:
  1. Melanocyte
  2. Ameloblasts of teeth
  3. Odontoblast of teeth
  4. Schwann cells
Q2. Which of the following acts as a primary inducer for neural tube formation?
  1. Primitive streak
  2. Prochordal plate
  3. Notochord
  4. Intraembryonic mesoderm
Q3. What is the most common cause of neural tube defects?
  1. Folic acid (vitamin B9) deficiency
  2. Vitamin B12 deficiency
  3. Vitamin D deficiency
  4. Iron deficiency
Q4. Alar lamina differentiates to form which of the following nuclei in medulla oblongata?
  1. Dorsal nucleus of vagus
  2. Nucleus ambiguus
  3. Hypoglossal nucleus
  4. Spinal nucleus of trigeminal nerve
Q5. The cerebral aqueduct is developed from the cavity of:
  1. Rhombencephalon
  2. Mesencephalon
  3. Telencephalon
  4. Diencephalon
Q6. The failure of closure of the cranial end of neural tube gives rise to:
  1. Anencephaly
  2. Hydrocephalus
  3. Microcephaly
  4. Meningomyelocele
Q7. By which week of intrauterine life does the whole neural tube close?
  1. Fourth
  2. Fifth
  3. Sixth
  4. Seventh
Q8. The cervical flexure of the neural tube occurs:
  1. Between the forebrain and midbrain
  2. In the midbrain
  3. Between the hindbrain and spinal cord
  4. In the hindbrain
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Q9. The third ventricle develops in the cavity of:
  1. Telencephalon
  2. Diencephalon
  3. Mesencephalon
  4. Rhombencephalon
Q10. All of the following nuclei are derivatives of basal lamina in pons, except:
  1. Abducent nucleus
  2. Lacrimatory nucleus
  3. Vestibular and cochlear nuclei
  4. Superior salivatory nucleus
 
Answers
1. B
2. C
3. A
4. D
5. B
6. A
7. A
8. C
9. B
10. C