Neuro Atlas

Atlas of 

Neuroanatomy and 

Neurophysiology 

Selections from the Netter Collection of Medical Illustrations 

Illustrations by 

Frank H. Netter, MD 

John A. Craig, MD 

James Perkins, MS, MFA 

Text by 

John T. Hansen, PhD 

Bruce M. Koeppen, MD, PhD

Atlas of Neuroanatomy and Neurophysiology 

Selections from the Netter Collection of Medical Illustrations 

Copyright ©2004 Icon Custom Communications. All rights reserved. 

The contents of this book may not be reproduced in any form without written 

authorization from Icon Custom Communications. Requests for permission 

should be addressed to Permissions Department, Icon Custom Communications, 

295 North St., Teterboro NJ 07608, or can be made at www. Netterart.com. 

NOTICE 

Every effort has been taken to confirm the accuracy of the information presented. 

Novartis, the publisher or the authors cannot be held responsible for errors or for 

any consequences arising from the use of the information contained herein, and 

make no warranty, expressed or implied, with respect to the contents of the publication. 

Printed in U.S.A.

Foreword 

Frank Netter: The Physician, The Artist, The Art 

This selection of the art of Dr. Frank H. Netter on neuroanatomy and neurophysiology is drawn 

from the Atlas of Human Anatomy and Netter’s Atlas of Human Physiology. Viewing these pictures 

again prompts reflection on Dr. Netter’s work and his roles as physician and artist. 

Frank H. Netter was born in 1906 in New York City. He pursued his artistic muse at the Sorbonne, 

the Art Student’s League, and the National Academy of Design before entering medical school at 

New York University, where he received his M.D. degree in 1931. During his student years, Dr. 

Netter’s notebook sketches attracted the attention of the medical faculty and other physicians, allowing 

him to augment his income by illustrating articles and textbooks. He continued illustrating as a 

sideline after establishing a surgical practice in 1933, but ultimately opted to give up his practice in 

favor of a full-time commitment to art. After service in the United States Army during the Second 

World War, Dr. Netter began his long collaboration with the CIBA Pharmaceutical Company (now 

Novartis Pharmaceuticals). This 45-year partnership resulted in the production of the extraordinary 

collection of medical art so familiar to physicians and other medical professionals worldwide. 

When Dr. Netter’s work is discussed, attention is focused primarily on Netter the artist and only 

secondarily on Netter the physician. As a student of Dr. Netter’s work for more than forty years, I can 

say that the true strength of a Netter illustration was always established well before brush was laid to 

paper. In that respect each plate is more of an intellectual than an artistic or aesthetic exercise. It is 

easy to appreciate the aesthetic qualities of Dr. Netter’s work, but to overlook its intellectual qualities 

is to miss the real strength and intent of the art. This intellectual process requires thorough understanding 

of the topic, as Dr. Netter wrote: “Strange as it may seem, the hardest part of making a medical 

picture is not the drawing at all. It is the planning, the conception, the determination of point of 

view and the approach which will best clarify the subject which takes the most effort.” 

Years before the inception of “the integrated curriculum,” Netter the physician realized that a 

good medical illustration can include clinical information and physiologic functions as well as anatomy. 

In pursuit of this principle Dr. Netter often integrates pertinent basic and clinical science elements 

in his anatomic interpretations. Although he was chided for this heresy by a prominent 

European anatomy professor, many generations of students training to be physicians rather than 

anatomists have appreciated Dr. Netter’s concept. 

The integration of physiology and clinical medicine with anatomy has led Dr. Netter to another, 

more subtle, choice in his art. Many texts and atlases published during the period of Dr. Netter’s 

career depict anatomy clearly based on cadaver specimens with renderings of shrunken and shriveled 

tissues and organs. Netter the physician chose to render “live” versions of these structures—not 

shriveled, colorless, formaldehyde-soaked tissues, but plump, robust organs, glowing with color! 

The value of Dr. Netter’s approach is clearly demonstrated by the plates in this selection. 

John A. Craig, MD 

Austin, Texas

This volume brings together two distinct but related aspects of the work of Frank 

H. Netter, MD, and associated artists. Netter is best known as the creator of the 

Atlas of Human Anatomy, a comprehensive textbook of gross anatomy that has 

become the standard atlas for students of the subject. But Netter’s work included 

far more than anatomical art. In the pages of Clinical Symposia, a series of monographs 

published over a period of more than 50 years, and in The Netter Collection 

of Medical Illustrations, this premier medical artist created superb illustrations of 

biological and physiological processes, disease pathology, clinical presentations, 

and medical procedures. 

As a service to the medical community, Novartis Pharma has commissioned this 

special edition of Netter’s work, which includes his beautiful and instructive illustrations 

of nervous system anatomy as well as his depictions of neurophysiological 

concepts and functions. We hope that readers will find Dr. Netter’s renderings of 

neurological form and function interesting and useful.

Part 1 Neuroanatomy 

Cerebrum—Medial Views . . . . . . . . . . . . . . . . . 2 

Cerebrum—Inferior View. . . . . . . . . . . . . . . . . . 3 

Basal Nuclei (Ganglia). . . . . . . . . . . . . . . . . . . . 4 

Thalamus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Cerebellum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Brainstem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Fourth Ventricle and Cerebellum . . . . . . . . . . . 8 

Accessory Nerve (XI) . . . . . . . . . . . . . . . . . . . . 9 

Arteries to Brain and Meninges . . . . . . . . . . . 10 

Arteries to Brain: Schema . . . . . . . . . . . . . . . . 11 

Arteries of Brain: Inferior Views . . . . . . . . . . . 12 

Cerebral Arterial Circle (Willis) . . . . . . . . . . . 13 

Arteries of Brain: Frontal View and Section . . 14 

Arteries of Brain: 

Lateral and Medial Views. . . . . . . . . . . . . . . 15 

Arteries of Posterior Cranial Fossa . . . . . . . . . 16 

Veins of Posterior Cranial Fossa . . . . . . . . . . . 17 

Deep Veins of Brain. . . . . . . . . . . . . . . . . . . . . 18 

Subependymal Veins of Brain . . . . . . . . . . . . . 19 

Hypothalamus and Hypophysis . . . . . . . . . . . 20 

Arteries and Veins 

of Hypothalamus and Hypophysis . . . . . . . . 21 

Relation of Spinal Nerve Roots to Vertebrae . . . 22 

Autonomic Nervous System: 

General Topography. . . . . . . . . . . . . . . . . . . 23 

Spinal Nerve Origin: Cross Sections. . . . . . . . 24 

Olfactory Nerve (I): Schema . . . . . . . . . . . . . . 25 

Optic Nerve (II) 

(Visual Pathway): Schema . . . . . . . . . . . . . . 26 

Oculomotor (III), Trochlear (IV) 

and Abducent (VI) Nerves: Schema. . . . . . . 27 

Trigeminal Nerve (V): Schema . . . . . . . . . . . . 28 

Facial Nerve (VII): Schema . . . . . . . . . . . . . . . 29 

Vestibulocochlear Nerve (VIII): Schema. . . . . 30 

Glossopharyngeal Nerve (IX): Schema . . . . . . 31 

Vagus Nerve (X): Schema . . . . . . . . . . . . . . . . 32 

Accessory Nerve (XI): Schema . . . . . . . . . . . . 33 

Hypoglossal Nerve (XII): Schema . . . . . . . . . . 34 

Nerves of Heart . . . . . . . . . . . . . . . . . . . . . . . . 35 

Autonomic Nerves 

and Ganglia of Abdomen. . . . . . . . . . . . . . . 36 

Nerves of Stomach and Duodenum . . . . . . . . 37 

Nerves of Stomach 

and Duodenum (continued) . . . . . . . . . . . . 38 

Nerves of Small Intestine . . . . . . . . . . . . . . . . 39 

Nerves of Large Intestine . . . . . . . . . . . . . . . . 40 

Nerves of Kidneys, 

Ureters and Urinary Bladder . . . . . . . . . . . . 41 

Nerves of Pelvic Viscera: Male . . . . . . . . . . . . 42 

Nerves of Pelvic Viscera: Female . . . . . . . . . . 43 

Median Nerve . . . . . . . . . . . . . . . . . . . . . . . . . 44 

Ulnar Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 

Radial Nerve in Arm 

and Nerves of Posterior Shoulder . . . . . . . . 46 

Radial Nerve in Forearm . . . . . . . . . . . . . . . . . 47 

Sciatic Nerve and Posterior 

Cutaneous Nerve of Thigh . . . . . . . . . . . . . . 48 

Tibial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 

Common Fibular (Peroneal) Nerve. . . . . . . . . 50

NEUROANATOMY 

Cerebrum: Medial Views 

Sagittal section of 

Cingulate gyrus 

brain in situ 

Cingulate sulcus 

Medial frontal gyrus 

Sulcus of corpus callosum 

Fornix 

Septum pellucidum 

Interventricular 

foramen (Monro) 

Interthalamic 

adhesion 

Thalamus and 

3rd ventricle 

Subcallosal 

(parolfactory) 

area 

Anterior 

commissure 

Subcallosal 

gyrus 

Hypothalamic 

sulcus 

Lamina 

terminalis 

Supraoptic 

recess 

Optic chiasm 

Tuber cinereum 

Hypophysis (pituitary gland) 

Mammillary body 

Cerebral peduncle 

Pons 

Medial surface of cerebral 

hemisphere: brainstem excised 


Mammillothalamic 

fasciculus 


Uncus 

Optic nerve (II) 

Olfactory tract 

Collateral sulcus 

Rhinal sulcus 

Medial occipitotemporal gyrus 

Occipitotemporal sulcus 

Lateral occipitotemporal gyrus 

Paracentral sulcus 

Central sulcus (Rolando) 

Paracentral lobule 

Marginal sulcus 

Corpus callosum 

Precuneus 

Superior sagittal sinus 

Choroid plexus 

of 3rd ventricle 

Stria medullaris 

of thalamus 

Parietooccipital 

sulcus 

Cuneus 

Habenular 

commissure 

Cerebral aqueduct 

(Sylvius) 

Pineal body 

Posterior 

commissure 

Calcarine 

sulcus 

Straight sinus 

in tentorium 

cerebelli 

Great cerebral vein 

(Galen) 

Superior colliculus 

Inferior colliculus 

Tectal (quadrigeminal) plate 

Cerebellum 

Superior medullary velum 

4th ventricle and choroid plexus 

Inferior medullary velum 

Medulla oblongata 

Genu 

Rostrum 

Trunk 

Splenium 

of 

corpus callosum 

Isthmus of cingulate gyrus 

Parietooccipital sulcus 

Cuneus 

Calcarine sulcus 

Lingual gyrus 

Crus 

Body 

Column 

of fornix 

Fimbria of hippocampus 

Dentate gyrus 

Parahippocampal gyrus 

2

Cerebrum: Inferior View 

NEUROANATOMY 

Sectioned brainstem 

Frontal pole of cerebrum 

Straight gyrus 

Olfactory sulcus 

Orbital sulci 

Longitudinal cerebral fissure 

Genu of corpus callosum 

Lamina terminalis 

Olfactory bulb 

Orbital gyri 

Temporal pole 

Lateral sulcus (Sylvius) 

Inferior temporal sulcus 

Inferior temporal gyrus 


Optic chiasm 

Optic nerve (II) (cut) 

Hypophysis 

(pituitary gland) 

Anterior 

perforated substance 

Optic tract 


Inferior (inferolateral) 

margin 

of cerebrum 

Rhinal sulcus 

Uncus 

Inferior 

temporal gyrus 

Occipitotemporal 

sulcus 

Lateral occipitotemporal 

gyrus 

Collateral sulcus 


Medial occipitotemporal gyrus 


Isthmus of cingulate gyrus 

Apex of cuneus 

Occipital pole of cerebrum 



Splenium of corpus callosum 


Posterior perforated 

substance (in 

interpeduncular 

fossa) 

Cerebral crus 

Lateral geniculate 

body 

Substantia nigra 

Medial geniculate 

body 

Red nucleus 

Pulvinar of thalamus 

Superior colliculus (of 

corpora quadrigemina) 

3

NEUROANATOMY 

Basal Nuclei (Ganglia) 

Horizontal sections 

through cerebrum 

A 

B 


Head of caudate nucleus 

Lateral ventricle 


Anterior limb 

Genu 

Posterior limb 

of internal 

capsule 

Column of fornix 

Insula 

(island of Reil) 

Interthalamic 

adhesion 

Putamen 

Globus pallidus 

3rd ventricle 

External capsule 

Lentiform 

nucleus 

Thalamus 

Claustrum 

Crus of fornix 

Retrolenticular part 

of internal capsule 


of lateral ventricle 

Tail of caudate nucleus 

Splenium of 

corpus callosum 

Hippocampus and fimbria 

Occipital (posterior) horn 


Habenula 

Organization of 

basal nuclei (ganglia) 

A 

B 

Pineal body 

Caudate 

nucleus 

Putamen Globus 

pallidus 

Cleft for internal capsule 

Striatum 

Corpus 

striatum 

Basal nuclei 

(ganglia) 

Lentiform 

nucleus 

Caudate 

nucleus 

Levels of 

sections 

above 

Body 

Head 

A 

B 

Lentiform nucleus 

(globus pallidus medial 

to putamen) 

Amygdaloid body 

Thalamus 

Pulvinar 

Medial geniculate body 

Lateral geniculate body 

Tail of caudate nucleus 

Interrelationship of thalamus, lentiform nucleus, caudate 

nucleus and amygdaloid body (schema): left lateral view 

A 

B 

4

Thalamus 

NEUROANATOMY 

Interventricular foramen (Monro) 

Tela choroidea (cut edge) 


3rd ventricle 


Superior thalamostriate vein 

Pes hippocampi 

Temporal (inferior) horn 


Internal cerebral vein 

Dentate gyrus 

Collateral eminence 

Hippocampus 


Posterior commissure 

Habenular commissure 

Pineal body 

Collateral trigone 

Calcar avis 




Corpus callosum (cut) 



Columns of fornix 

Anterior tubercle 

Stria terminalis 

Interthalamic adhesion 

Lamina affixa 

Stria medullaris 

Habenular trigone 

Pulvinar (retracted) 



Brachium of superior colliculus 

Brachium of inferior colliculus 



Cerebellum 

Internal 

medullary 

lamina 

MD 

M 

CM 

VPM 

LP 

VPL 

Pulvinar 

Intralaminar 

nuclei 

Reticular nucleus 

Interthalamic 

adhesion 

3rd ventricle 

Internal 

Median 

Medial 

LP 

VP 

Lamina 

LD 

medullary lamina 

VPL VPM VI 

Anterior 

VL 

VA 

3rd ventricle 

Median nuclei 

External 

medullary 

lamina 

Schematic section 

through thalamus 

(at level of broken 

line shown in figure 

at right) 

Thalamic nuclei 

CM Centromedian 

LD Lateral dorsal 

LP Lateral posterior 

M Medial 

MD Medial dorsal 

VA Ventral anterior 

VI Ventral intermedial 

VL Ventral lateral 

VP Ventral posterior 

VPL Ventral posterolateral 

VPM Ventral posteromedial 

Pulvinar 



Schematic representation of thalamus 

(external medullary lamina and 

reticular nuclei removed) 

Lateral nuclei 

Medial nuclei 

Anterior nuclei 

5

NEUROANATOMY 

Cerebellum 

Superior 

vermis 

Anterior cerebellar notch 

Central lobule (II & III) 

Culmen (IV & V) 

Declive (VI) 

Folium (VII A) 

Posterior cerebellar notch 

Superior surface 

Anterior lobe 

Quadrangular lobule (H IV-V) 

Primary fissure 

Horizontal fissure 

Simple lobule (H VI) 

Posterior lobe 

Postlunate fissure 

Superior semilunar 

(anseriform) lobule (H VII A) 


Inferior semilunar 

(caudal) lobule (H VII B) 

Superior vermis 

Central lobule 

Lingula (I) 


Flocculus (H X) 

4th ventricle 


Inferior 

vermis 

Nodule (X) 

Uvula (IX) 

Pyramid (VIII) 

Tuber (VII B) 

Posterior cerebellar notch 

Inferior surface 

Anterior lobe 

Wing of central lobule 

Superior 

Middle Cerebellar peduncles 

Inferior 

Flocculonodular lobe 

Posterolateral (dorsolateral) 

fissure 

Retrotonsillar fissure 

Posterior lobe 

Tonsil 

Biventer lobule (H VIII) 

Secondary (postpyramidal) 

fissure 


Inferior semilunar 

(caudal) lobule (H VII B) 

Decussation of 

superior cerebellar peduncles 

4th ventricle 


Cerebral crus 

Medial longitudinal fasciculus 

Nuclear layer of 

medulla oblongata 

Cerebellar 

nuclei 

Fastigial 

Globose 

Dentate 

Emboliform 

Superior cerebellar 

peduncle 

Lingula (I) 

Vermis 

Section in plane of superior cerebellar peduncle 

6

Brainstem 

NEUROANATOMY 

Posterolateral view 

Pulvinars of thalami 

Pineal body 

Superior colliculi 

Inferior colliculi 

Trochlear nerve (IV) 


Superior cerebellar peduncle 

Rhomboid fossa of 

4th ventricle 

Glossopharyngeal (IX) and 

vagus (X) nerves 

Cuneate tubercle 

Gracile tubercle 

Dorsal roots of 

1st spinal nerve (C1) 

Cuneate fasciculus 

Gracile fasciculus 

Thalamus (cut surface) 


Optic tract 


Brachia of superior and inferior colliculi 

Cerebral crus 

Pons 

Trigeminal nerve (V) 

Middle cerebellar peduncle 

Vestibulocochlear nerve (VIII) 

Facial nerve (VII) 

Inferior cerebellar peduncle 

Hypoglossal nerve (XII) 

Accessory nerve (XI) 


Anterior view 

Optic chiasm 

Optic tract 


Cerebral crus 


Posterior perforated substance 

Pons 


Olive 

Pyramid 

Ventral roots of 1st spinal nerve (C1) 

Decussation of pyramids 

Anterior perforated substance 

Infundibulum (pituitary stalk) 

Mammillary bodies 

Temporal lobe (cut surface) 

Oculomotor nerve (III) 



Abducent nerve (VI) 

Facial nerve (VII) and 

intermediate nerve 

Vestibulocochlear nerve (VIII) 

Flocculus of cerebellum 

Choroid plexus of 4th 

ventricle 

Glossopharyngeal nerve (IX) 

Vagus nerve (X) 


Accessory nerve (XI) 

7

NEUROANATOMY 

Fourth Ventricle and Cerebellum 

Posterior view 

3rd ventricle 


Pineal body 





Superior 

Cerebellar peduncles Middle 

Inferior 

Lateral recess 

Superior fovea 

Sulcus limitans 

Inferior fovea 

Trigeminal tubercle 

Hypoglossal trigone 

Vagal trigone 

Obex 

Gracile fasciculus 

Habenular trigone 

Medial 

Geniculate bodies 

Lateral 

Dorsal median sulcus 


Locus ceruleus 

Medial eminence 

Facial colliculus 

Vestibular area 

Lateral funiculus 

Cuneate fasciculus 

Dentate nucleus 

of cerebellum 

Striae medullares 

Tenia of 4th ventricle 

Cuneate tubercle 

Gracile tubercle 

Dorsal median sulcus 

Median sagittal section 

Body of fornix 

Thalamus (in 

3rd ventricle) 



Anterior commissure 


Hypothalamic sulcus 


Cerebral aqueduct (Sylvius) 


Tectal (quadrigeminal) plate 


Pons 

Medial longitudinal fasciculus 

4th ventricle 

Choroid plexus of 4th ventricle 


Median aperture (foramen of Magendie) 

Decussation of pyramids 

Central canal of spinal cord 


Posterior commissure 

Habenular commissure 

Pineal body 


Great cerebral vein (Galen) 


Tonsil of cerebellum 

Lingula (I) 

Central lobule (II-III) 

Culmen (IV-V) 

Declive (VI) 

Folium (VII A) 



Tuber (VII B) 

Pyramid (VIII) 

Uvula (IX) 

Nodulus (X) 

Vermis of 

cerebellum 

Vermis of 

cerebellum 

8

Accessory Nerve (XI): Schema 

NEUROANATOMY 

Nucleus ambiguus 


Cranial root of accessory nerve (joins vagus nerve 

and via recurrent laryngeal nerve supplies muscles of 

larynx, except cricothyroid)* 

Spinal root of 

accessory nerve 

Jugular foramen 

Foramen 

magnum 

Superior ganglion 

of vagus nerve 

Accessory nerve (XI)* 

Inferior ganglion 


C1 spinal nerve 


Accessory nerve 

(to sternocleidomastoid 

and trapezius muscles) 

Sternocleidomastoid muscle (cut) 



Trapezius muscle 

*Recent evidence suggests that the accessory nerve lacks a cranial root and has no connection to the vagus nerve. 

Verification of this finding awaits further investigation. 

Efferent fibers 

Proprioceptive fibers 

9

NEUROANATOMY 

Arteries to Brain and Meninges 

Mastoid branch of 

left occipital artery 

Anterior inferior 

cerebellar artery 

Posterior inferior 


Left middle meningeal artery 

Posterior cerebral artery 

Superior cerebellar artery 

Basilar artery 

Left labyrinthine 

(internal acoustic) artery 

Posterior meningeal 

branch of left ascending 

pharyngeal artery 

Left and right 

vertebral arteries 

(intracranial part) 

Posterior meningeal 

branch of vertebral 

artery 

Anterior meningeal 

branch of vertebral artery 

Posterior auricular artery 

Occipital artery 

Middle cerebral artery 

Anterior cerebral artery 

Anterior communicating artery 

Ophthalmic artery 

Posterior 

communicating 

artery 

Cavernous sinus 

Lingual artery 

Middle 

meningeal 

artery 

Maxillary 

artery 

Superficial 

temporal 

artery 

External 

carotid 

artery 

Facial artery 

Internal carotid artery 

Carotid sinus 

Carotid body 

Vertebral artery 

(cervical part) 

Transverse process of C6 

Deep cervical artery 

Supreme intercostal 

artery 

Costocervical trunk 

Subclavian artery 

Ascending pharyngeal artery 

Superior laryngeal artery 

Superior thyroid artery 

Common carotid artery 

Ascending cervical artery (cut) 

Inferior thyroid artery 

Thyrocervical trunk 

Brachiocephalic trunk 

Internal thoracic artery 

10

Arteries to Brain: Schema 

NEUROANATOMY 



1 



Posterior communicating artery 

Caroticotympanic branch 

of internal carotid artery 



Anterior tympanic artery 

Middle meningeal artery 

Maxillary artery 


Anterior inferior 


4 

3 

3 

3 

3 

4 

5 

5 

5 

5 

2 

1 

1 

1 

Supraorbital artery 

Supratrochlear artery 

Lacrimal artery 

Dorsal nasal artery 

Middle meningeal artery 

Angular artery 

Superficial temporal artery 

Posterior auricular artery 

Facial artery 

Occipital artery 

Lingual artery 

Ascending pharyngeal artery 

Posterior inferior 


External carotid artery 


5 

5 

5 

Anterior spinal artery 

Spinal segmental 

medullary branches 



Superior thyroid artery 


5 

Deep cervical artery 

Transverse cervical artery 


Ascending cervical artery 

Suprascapular artery 

Supreme intercostal artery 

Costocervical trunk 


Thyrocervical trunk 



Internal thoracic artery 

Brachiocephalic trunk 

Aorta 

Arch 

Descending 

Ascending 

Anastomoses 

1 Right–Left 

2 Carotid–Vertebral 

3 Internal carotid–External carotid 

4 Subclavian–Carotid 

5 Subclavian–Vertebral 

11

NEUROANATOMY 

Arteries of Brain: Inferior Views 

Medial frontobasal (orbitofrontal) artery 



Distal medial striate artery 

(recurrent artery of Heubner) 


Anterolateral central (lenticulostriate) arteries 


Lateral frontobasal (orbitofrontal) artery 

Prefrontal artery 

Anterior choroidal artery 





Pontine arteries 

Labyrinthine (internal acoustic) artery 

Anterior inferior cerebellar artery 



Posterior inferior cerebellar artery (PICA) (cut) 

Posterior spinal artery 








Optic tract 


Cerebral crus 


Posterior medial choroidal artery 

Posterior lateral choroidal artery 

Choroid plexus of lateral ventricle 




Cerebral arterial 

circle (Willis) 

(broken line) 

12

Cerebral Arterial Circle (Willis) 

NEUROANATOMY 

Vessels dissected out: inferior view 


(A 2 segment) 



(A 1 segment) 





Anteromedial central (perforating) 

arteries 

Hypothalamic artery 

Anterolateral central 

(lenticulostriate) arteries 




(P 2 segment) 

(P 1 segment) 





Superior hypophyseal artery 

Inferior hypophyseal artery 


Thalamotuberal 

(premammillary) artery 

Posteromedial central 

(perforating) arteries 

Thalamoperforating artery 


(paramedian) arteries 



Vessels in situ: inferior view 


Hypothalamic artery 


Superior hypophyseal artery 




Efferent hypophyseal veins 



Optic chiasm 

Cavernous sinus 


and long hypophyseal portal veins 

Adenohypophysis (anterior 

lobe of pituitary gland) 

Neurohypophysis (posterior 

lobe of pituitary gland) 


(perforating) arteries 



13

NEUROANATOMY 

Arteries of Brain: Frontal View and Section 

Prefrontal artery 




Lateral frontobasal 

(orbitofrontal) artery 

Precentral (pre-rolandic) 

and central (rolandic) 

sulcal arteries 

Anterior parietal 

(postcentral sulcal) 

artery 

Posterior parietal 

artery 

Branch to 

angular gyrus 

Temporal branches 

(anterior, middle 

and posterior) 


and branches 

(deep in lateral cerebral 

[sylvian] sulcus) 




Posterior spinal artery 

Corpus striatum 

(caudate and lentiform nuclei) 



Insula (island of Reil) 

Limen of insula 

Precentral (pre-rolandic), 

central (rolandic) sulcal 

and parietal arteries 

Lateral cerebral (sylvian) sulcus 

Temporal branches of 

middle cerebral artery 

Temporal lobe 



Paracentral artery 

Medial frontal branches 

Pericallosal artery 

Callosomarginal artery 

Polar frontal artery 

Anterior cerebral 

arteries 

Medial frontobasal 


Distal medial striate 

artery (recurrent 

artery of Heubner) 

Internal carotid 

artery 

Anterior choroidal 

artery 

Posterior cerebral 

artery 


Basilar and pontine arteries 

Labyrinthine (internal 

acoustic) artery 


Posterior inferior cerebellar artery 


Falx cerebri 

Callosomarginal arteries 

and 

Pericallosal arteries 

(branches of anterior 

cerebral arteries) 

Trunk of corpus callosum 

Internal capsule 


Rostrum of corpus callosum 

Anterior cerebral arteries 




Optic chiasm 

14

Arteries of Brain: Lateral and Medial Views 

NEUROANATOMY 

Precentral (pre-rolandic) sulcal artery 

Prefrontal sulcal 

artery 

Anterior parietal (postcentral sulcal) artery 

Central (rolandic) sulcal artery 

Posterior parietal artery 

Branch to angular gyrus 

Terminal branches 

of posterior 

cerebral artery 

Terminal branches of 

anterior cerebral 

artery 

Lateral frontobasal 


Left middle 


Left anterior 



Right anterior cerebral artery 

Left internal carotid artery 

Polar temporal artery 

Occipitotemporal 

branches 

Posterior temporal branch 

Middle temporal branch 

Superior and inferior terminal branches (trunks) 

Anterior temporal branch 

Medial 

frontal 

branches 

Callosomarginal 

artery 

Polar frontal artery 

Right anterior 


Posterior 

Intermediate 

Anterior 

Pericallosal artery 

Paracentral artery 

Cingular branches 

Right posterior cerebral artery 

Precuneal artery 

Dorsal branch 

to corpus callosum 

Parietooccipital branch 

Calcarine branch 

Medial frontobasal 

(orbitofrontal) 

artery 

Anterior 

communicating artery (cut) 



Right internal carotid artery 

Medial occipital artery 

Posterior temporal branch 

Anterior temporal branch 


Note: Anterior parietal (postcentral sulcal) artery also occurs as separate anterior parietal and postcentral sulcal arteries 

15

NEUROANATOMY 

Arteries of Posterior Cranial Fossa 

Thalamogeniculate arteries 


Crura of fornix 



Heads of caudate nuclei 



Anterior 

cerebral arteries 

Longitudinal 

cerebral 

fissure 

Lateral and medial geniculate bodies of left thalamus 

Choroid plexuses of lateral ventricles 

Pulvinars of left and right thalami 


Occipital (posterior) horn of right lateral ventricle 

Right dorsal branch to corpus callosum 

(posterior pericallosal artery) 

Parietooccipital Branches of 

right posterior 

Calcarine cerebral artery 

Superior 

colliculi 

Optic nerve (II) 


Anterior 


Middle 


Posterior 

communicating artery 

Thalamoperforating arteries 

Left internal carotid artery 






III 


Anterior meningeal branch of vertebral artery 

Temporal branches of posterior cerebral artery 


VI 

IV 

V 

VIII 

VII 

IX 

X 

XI 

Posterior medial 

choroidal artery 

to choroid plexus 


Posterior lateral 

choroidal artery 

Lateral (marginal) branch 

Inferior vermian artery 

(phantom) 

Choroidal branch to 4th ventricle 

(phantom) and 

Cerebellar tonsillar branch 

of posterior inferior cerebellar artery 

Outline of 4th ventricle (broken line) 

Posterior meningeal branch of vertebral artery 

Posterior inferior cerebellar artery (PICA) 

Left posterior spinal artery 

Left vertebral artery 

Superior 

vermian 

branch 

16

Veins of Posterior Cranial Fossa 

NEUROANATOMY 

Left superior and inferior colliculi 

Basal vein (Rosenthal) 

Posterior mesencephalic vein 



Left thalamus 

(cut surface) 

Optic tract 

Inferior thalamostriate 

veins 

Deep middle 

cerebral 

vein (cut) 

Anterior 

cerebral 

vein 

Optic 

nerve (II) 

Lateral 

mesencephalic vein 

Left pulvinar 

Right pulvinar 

Internal cerebral veins 



Dorsal vein of corpus callosum 

Inferior sagittal sinus 


Falx cerebri 

Tentorium 

cerebelli (cut) 

Confluence of sinuses 

Left transverse 

sinus (cut) 

Superior 

sagittal 

sinus 

Anterior pontomesencephalic 

vein 


Transverse pontine vein 

Petrosal vein (draining 

to superior petrosal sinus) 

Lateral pontine vein 

Anteromedian medullary vein 

Vein of lateral recess of 4th ventricle 

Superior, middle and 

inferior cerebellar peduncles 

Anterior spinal vein 

L 

CL 

N 

T 

C 

4th ventricle 

U 

C 

Posterior spinal vein 

P 

D 

F 

TU 

Preculminate vein 

Precentral cerebellar vein 

Superior retrotonsillar vein 

(Inferior retrotonsillar) 

vein of cerebellomedullary 

cistern 

Superior 

vermian 

vein 

Inferior 

vermian vein 

Falx cerebelli (cut) 

and occipital sinus 

Inferior cerebellar 

hemispheric veins 

Intraculminate vein 

Superior cerebellar vein (inconstant) 

Parts of cerebellum 

L Lingula TU Tuber 

CL Central lobule P Pyramid 

C Culmen U Uvula 

D Declive N Nodule 

F Folium T Tonsil 

17

NEUROANATOMY 

Deep Veins of Brain 


Anterior cerebral veins 

Rostrum of corpus callosum 


Anterior vein of septum pellucidum 


Anterior vein of caudate nucleus 

Transverse veins of caudate nucleus 

Interventricular foramen (Monro) 



Superior choroid vein and 

choroid plexus of lateral ventricle 

Thalamus 

Tela choroidea of 3rd ventricle 

Lateral direct vein 

Posterior vein of caudate nucleus 

Internal cerebral veins 



Inferior sagittal sinus 


Tentorium cerebelli 

Transverse sinus 

Confluence of sinuses 


Dissection: superior view 

Uncal vein 

Anterior cerebral vein 

Superficial middle cerebral vein 

(draining to sphenoparietal sinus) 

Deep middle cerebral vein 

Optic chiasm 

Cerebral crus 




Inferior 

cerebral 

veins 




Inferior 

anastomotic 

vein (Labbé) 

Dissection: inferior view 

18

Subependymal Veins of Brain 

NEUROANATOMY 

Posterior veins of septum pellucidum 

Superior thalamic veins 

Superior choroid vein 

Transverse veins of caudate nucleus 



Anterior vein of 

caudate nucleus 

Anterior vein of 

septum pellucidum 

Genu of 

corpus 

callosum 

Lateral direct vein 

Posterior terminal vein of caudate nucleus 

(posterior part of thalamostriate vein) 

Internal cerebral veins (right and left) 

Medial (atrial) vein of lateral ventricle 

Lateral (atrial) vein of lateral ventricle 


Great cerebral vein 

(Galen) 

Dorsal vein of corpus 

callosum 

Inferior sagittal 

sinus 

Internal 

occipital vein 


Occipital 

(posterior) 

horn of 

lateral 

ventricle 





Anterior cerebral vein 

Optic chiasm 

3rd ventricle 

Cerebellum 

Deep middle cerebral vein 

Inferior thalamostriate veins 


Temporal (inferior) horn of lateral ventricle 

Posterior mesencephalic vein 

Hippocampal and inferior ventricular veins 


4th ventricle 

Lateral and median apertures of 4th ventricle 

Superior vermian vein 

Veins on lateral wall of ventricle 

Veins on medial wall and floor of ventricle 

All other veins 

19

NEUROANATOMY 

Hypothalamus and Hypophysis 


Thalamus 

Fornix 

Hypothalamic sulcus 


Principal 

nuclei of 

hypothalamus 

Paraventricular 

Posterior 

Dorsomedial 

Supraoptic 

Ventromedial 

Arcuate 

(infundibular) 

Mammillary 

Optic chiasm 


Hypophysis (pituitary gland) 

Mammillothalamic tract 

Dorsal longitudinal 

fasciculus and other 

descending pathways 


Paraventricular hypothalamic nucleus 

Hypothalamic 

sulcus 

Supraoptic hypothalamic nucleus 

Supraopticohypophyseal tract 

Tuberohypophyseal tract 

Hypothalamohypophyseal tract 


Mammillary 

body 

Arcuate (infundibular) nucleus 

Adenohypophysis 

(anterior lobe of 

pituitary gland) 

Pars tuberalis 

Fibrous trabecula 

Pars intermedia 

Pars distalis 

Cleft 

Median eminence 

of tuber cinereum 

Infundibular 

stem 

Infundibular 

process 

Neurohypophysis 

(posterior lobe 

of pituitary gland) 

20

Arteries and Veins of Hypothalamus and Hypophysis 

NEUROANATOMY 

Hypothalamic vessels 

Primary plexus of 

hypophyseal portal system 

Superior 

hypophyseal 

artery 

Artery of trabecula 

Trabecula (fibrous tissue) 

Efferent hypophyseal vein 

to cavernous sinus 

Long hypophyseal portal veins 

Short hypophyseal portal veins 



Secondary plexus 

of hypophyseal 

portal system 

Neurohypophysis 

(posterior lobe of 


Adenohypophysis 

(anterior lobe of 


Capillary plexus of 

infundibular process 



Efferent hypophyseal 

veins to cavernous sinus 


21

NEUROANATOMY 

Relation of Spinal Nerve Roots to Vertebrae 

Cervical 

enlargement 

Lumbar 

enlargement 

Base 

of skull 

C1 

C2 

C3 

C4 

C5 

C6 

C7 

T1 

T2 

T3 

T4 

T5 

T6 

T7 

T8 

T9 

T10 

C1 

C2 

C3 

C4 

C5 

C6 

C7 

C8 

T1 

T2 

T3 

T4 

T5 

T6 

T7 

T8 

T9 

T10 

T11 

T11 

T12 

T12 

L1 

L1 

L2 

C1 spinal nerve exits 

above C1 vertebra 


exits below 

C7 vertebra 

(there are 8 cervical 

nerves but only 

7 cervical vertebrae) 

Conus medullaris 

(termination of 

spinal cord) 

S1 

S2 

L4 

L5 

Lumbar disc protrusion does not usually affect 

nerve exiting above disc. Lateral protrusion 

at disc level L4–5 affects L5 spinal nerve, not 

L4 spinal nerve. Protrusion at disc level L5–S1 

affects S1 spinal nerve, not L5 spinal nerve 

L4 

L4 

L5 

L4 

Internal terminal 

filum (pial part) 

L3 

L4 

L2 

L3 

L4 

Cauda equina 

L5 

L5 

External 

terminal filum 

(dural part) 

S2 

S3 

Termination of 

S4 dural sac 

S5 

Coccygeal nerve 

Coccyx 

L5 

L5 

Sacrum 

S1 

Cervical nerves 

Thoracic nerves 

Lumbar nerves 

Sacral and coccygeal nerves 

S1 

S2 

S3 

S4 

S5 


Medial protrusion at disc level L4–5 rarely affects 

L4 spinal nerve but may affect L5 spinal nerve 

and sometimes S1–4 spinal nerves 

22

Autonomic Nervous System: General Topography 

NEUROANATOMY 





Internal carotid nerve and plexus 

Superior cervical sympathetic ganglion 


Middle cervical sympathetic ganglion 

Vertebral ganglion 

Cervicothoracic (stellate) ganglion 

Cervical (sympathetic) 

cardiac nerves 

Sympathetic trunk 

Superior 

Middle 

Inferior 

Thoracic (sympathetic) cardiac nerves 

6th intercostal nerve 

(ventral ramus of T6 

spinal nerve) 


6th thoracic sympathetic ganglion 

Gray and white rami communicantes 

Greater splanchnic nerve 

Lesser splanchnic nerve 

Least splanchnic nerve 

Aorticorenal ganglion 

Lumbar splanchnic nerves (sympathetic) 

Gray rami communicantes 

Sacral splanchnic nerves (sympathetic) 

Pelvic splanchnic nerves 

(sacral parasympathetic 

outflow) 

Sciatic nerve 

Inferior hypogastric 

(pelvic) plexus 

Sympathetic fibers 

Parasympathetic fibers 

Ciliary ganglion 

Pterygopalatine ganglion 

Otic ganglion 

Chorda tympani nerve 

Lingual nerve 

Submandibular ganglion 

Pharyngeal and superior laryngeal branches 


Recurrent laryngeal branch of vagus nerve 

Superior cervical 

Inferior cervical 

Thoracic 

Cardiac plexus 

Anterior 

Posterior 

Esophageal plexus 

Cardiac branches 


Pulmonary plexuses 

Thoracic aortic plexus 

Anterior vagal trunk 

Posterior vagal trunk 

Celiac ganglion 

Celiac trunk and plexus 

Superior mesenteric ganglion 

Superior mesenteric artery 

and plexus 

Intermesenteric 

(abdominal aortic) plexus 

Inferior mesenteric ganglion 

Inferior mesenteric artery 

and plexus 

Superior hypogastric plexus 

Parasympathetic branch from 

inferior hypogastric plexus to 

descending colon 

Hypogastric nerves 

Rectal plexus 

Vesical plexus 

Prostatic plexus 

23

NEUROANATOMY 

Spinal Nerve Origin: Cross Sections 

Section through thoracic vertebra 

Aorta 

Fat in epidural space 

Sympathetic ganglion 

Ventral root 

White and gray rami 

communicantes 

Spinal nerve 

Ventral ramus 

(intercostal nerve) 

Dorsal ramus 

Body of vertebra 

Dura mater 

Arachnoid mater* 

Subarachnoid space 

Pia mater* 

Recurrent 

meningeal 

branches of 

spinal nerve 

Pleura 

Lung 

Spinal sensory 

(dorsal root) ganglion 

Dorsal root 

Lateral horn of 

gray matter of spinal cord 

Section through lumbar vertebra 

Sympathetic 

ganglion 

Dura mater 

Lateral branch 

Medial branch 

of dorsal 

ramus 

of spinal 

nerve 

Gray ramus 

communicans 

Fat in 

epidural 

space 

Arachnoid mater 

Ventral root 

Spinal nerve 

Internal vertebral 

(epidural) venous plexus 

Ventral ramus (contributes to lumbar plexus) 

Dorsal ramus 

Dorsal and ventral 

roots of lumbar and 

sacral spinal nerves 

forming cauda equina 

Spinal sensory (dorsal root) ganglion 

Dorsal root 


*Leptomeninges 

24

Olfactory Nerve (I): Schema 

NEUROANATOMY 

Olfactory bulb cells: schema 

Efferent fibers to 

olfactory bulb 

Afferent fibers from bulb 

to central connections 

and contralateral bulb 

Granule cell (excited by 

and inhibiting to mitral 

and tufted cells) 

Mitral cell 

Recurrent process 

Tufted cell 

Periglomerular 

cell 

Glomerulus 

Olfactory 

nerve fibers 

Subcallosal (parolfactory) area 

Septal area and nuclei 

Fibers from 

Fibers to 

Contralateral 

olfactory bulb 


Medial 

olfactory stria 

Olfactory cells 


Olfactory mucosa 

Olfactory nerves (I) 


Cribriform plate of ethmoid bone 

Anterior olfactory nucleus 

Olfactory trigone 

and olfactory tubercle 

Lateral olfactory stria 

Lateral olfactory tract nucleus 

Anterior perforated substance 

Amygdaloid body (phantom) 

Piriform lobe 

Uncus 

Hippocampal 

fimbria 

Dentate gyrus 


25

NEUROANATOMY 

Optic Nerve (II) (Visual Pathway): Schema 

G 

A 

B 

H 

G 

B 

A 

H 

Overlapping 

visual fields 

Central darker 

circle represents 

macular zone 

Lighter shades 

represent 

monocular fields 

Each quadrant 

a different color 

R R C 

C 

Projection on 

left retina 

Projection on 

right retina 

P 

Choroid 

Periphery 

P 

Choroid 

Macula 

Optic nerves (II) 

Optic chiasm 

Structure of retina: schema 

A Amacrine cells 

B Bipolar cells 

C Cones 

G Ganglion cells 

H Horizontal cells 

P Pigment cells 

R Rods 

Projection on left 

dorsal lateral 

geniculate nucleus 

Optic tracts 

Lateral 

geniculate 

bodies 

Projection on right 



Optic radiation 

Optic radiation 

Calcarine 

sulcus 

Calcarine 

sulcus 


occipital lobe 



26

Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves: Schema 

NEUROANATOMY 

Long ciliary nerve 

Short ciliary nerves 

Anterior ethmoidal nerve 

Superior oblique muscle 

Levator palpebrae 

superioris muscle 

Superior 

rectus muscle 


Posterior ethmoidal nerve 

Sensory root of ciliary ganglion 

Sympathetic root of ciliary ganglion 

Superior division of 

oculomotor nerve 

Frontal nerve (cut) 

Lacrimal nerve (cut) 

Nasociliary nerve 

Abducent nucleus 

Trochlear nucleus 

Oculomotor nucleus 

Accessory oculomotor 

(Edinger-Westphal) 

nucleus (parasympathetic) 



Ophthalmic nerve (V 1 ) 

Infraorbital nerve 

Zygomatic nerve (cut) 

Inferior oblique muscle 

Ciliary muscle 

Dilator muscle of pupil 

Sphincter muscle of pupil 


Afferent fibers 



Pterygopalatine 

ganglion 

Inferior division of 

oculomotor nerve 

Medial rectus muscle 

Inferior rectus muscle 

Parasympathetic root 

of ciliary ganglion 

Abducent 

nerve (VI) 

Mandibular nerve (V 3 ) 


and nerve plexus 

Maxillary nerve (V 2 ) 

Lateral rectus muscle and 

abducent nerve (turned back) 

Cavernous plexus 

Common tendinous ring 

27

NEUROANATOMY 

Trigeminal Nerve (V): Schema 






Frontal nerve 


Posterior ethmoidal nerve 

Long ciliary nerve 

Short ciliary nerves 

Anterior ethmoidal nerve 

Supraorbital nerve 

Supratrochlear nerve 

Infratrochlear nerve 

Internal nasal branches 

and 

External nasal branches 

of anterior ethmoidal nerve 

Maxillary nerve (V 2 ) 

Meningeal branch 

Zygomaticotemporal 

nerve 

Zygomaticofacial nerve 

Zygomatic nerve 

Infraorbital nerve 


ganglion 

Superior 

alveolar 

branches of 

infraorbital nerve 

Nasal branches 

(posterior superior 

lateral, nasopalatine 

and posterior 

superior medial) 

Nerve (vidian) of 

pterygoid canal 

(from facial nerve [VII] 

and carotid plexus) 

Pharyngeal branch 

Greater and lesser 

palatine nerves 

Ophthalmic nerve (V 1 ) 

Tentorial (meningeal) branch 

Nasociliary nerve 

Lacrimal nerve 

Sensory root of 

ciliary ganglion 

Trigeminal nerve (V) ganglion and nuclei 

Motor nucleus 

Mesencephalic nucleus 

Principal sensory nucleus 

Spinal tract and nucleus 


Chorda 

tympani nerve 

Deep temporal nerves 

(to temporalis muscle) 

Lateral pterygoid 

and masseteric nerves 

Tensor veli palatini and 

medial pterygoid nerves 

Buccal nerve 

Mental nerve 

Inferior dental plexus 

Lingual nerve 

Submandibular 

ganglion 

Mylohyoid nerve 


Inferior 

alveolar nerve 

Otic ganglion 

Tensor tympani nerve 

Superficial 

temporal branches 

Articular branch 

and anterior 

auricular nerves 

Auriculotemporal nerve 

Parotid branches 


Lesser petrosal nerve (from 

glossopharyngeal nerve [IX]) 

28

Facial Nerve (VII): Schema 

NEUROANATOMY 

Greater petrosal nerve 

Deep petrosal nerve (from internal carotid plexus) 

Lesser petrosal nerve 

Nerve (vidian) of pterygoid canal 

Otic ganglion 


Facial muscles 


Geniculate ganglion 

Internal carotid plexus 

(on internal carotid artery) 

Internal acoustic meatus 

Intermediate nerve 

Motor nucleus of facial nerve 

Superior salivatory nucleus 

Solitary tract nucleus 

Frontal belly (frontalis) 

of occipitofrontalis 

Orbicularis oculi 

Corrugator supercilii 

Zygomaticus major 

Zygomaticus minor 

Procerus 

Levator labii 

superioris 

Levator labii 

superioris 

alaeque nasi 

Levator 

anguli oris 

Nasalis 

Temporal 

branches 

Depressor 

septi nasi 

Orbicularis 

oris 

Depressor 

anguli oris 

Depressor labii 

inferioris 

Mentalis 

(Risorius) 

(not shown) 

Buccinator 

Platysma 

Taste: 

of 

anterior 2 ⁄3 

tongue 

Zygomatic 

Marginal 

mandibular 

branch 

branches 

Buccal 

branches 

Sublingual gland 

Submandibular gland 




Parasympathetic fibers Lingual nerve (from trigeminal nerve) 



Cervical branch 

Tympanic nerve (Jacobson) 

(from glossopharyngeal nerve) 


Digastric muscle (posterior belly) 

Stylohyoid muscle 

Nerve to stapedius muscle 

Stylomastoid foramen 

Tympanic plexus 

Occipital 

branch of 

posterior 

auricular 

nerve 

Branches to auricular muscles 

Posterior auricular nerve 

Caroticotympanic nerve (from internal carotid plexus) 

Occipital 

belly 

(occipitalis) of 

occipitofrontalis 

muscle 

29

NEUROANATOMY 

Vestibulocochlear Nerve (VIII): Schema 


Geniculum of facial nerve 

(site of geniculate ganglion) 


Facial canal 

Tympanic cavity 


Head of malleus 

Cochlear (spiral) ganglion 

Incus 

Vestibular nerve 

Cochlear nerve 

Motor root of facial nerve 

and intermediate nerve 

Vestibulocochlear 

nerve (VIII) 


(cross section) 

Medial 

Internal 

acoustic 

meatus 

Ampulla of lateral 

semicircular duct 

Ampulla of superior 


Vestibular 

nuclei 

(diagrammatic) 

Superior 

Inferior 

Lateral 

Anterior 

Posterior 

Cochlear 

nuclei 


peduncle (to cerebellum) 

Saccule 

Utricle 

Ampulla of posterior 


Vestibular ganglion 

Superior division 

Inferior division 

of vestibular nerve 

30

Glossopharyngeal Nerve (IX): Schema 

NEUROANATOMY 


Spinal tract and spinal nucleus of trigeminal nerve 


Solitary tract nucleus 

Parasympathetic fibers Tympanic nerve (Jacobson) 


Tympanic cavity and plexus 

Inferior salivatory nucleus 

Stylomastoid foramen 


of facial nerve 

Caroticotympanic nerve (from internal carotid plexus) 


Deep petrosal nerve 

Nerve (vidian) of pterygoid canal 

Lesser petrosal nerve 



Otic ganglion 

Auriculotemporal nerve 

Parotid gland 

Tubal branch of tympanic plexus 

Pharyngotympanic (auditory) 

tube and pharyngeal opening 

Stylopharyngeus muscle (and branch 

Glossopharyngeal 

from glossopharyngeal nerve) 

nerve (IX) 


Communication to auricular 

branch of vagus nerve 

Superior and 

Inferior ganglia of 

Glossopharyngeal nerve 

Taste and 

somatic 

sensation: 

posterior 

1 

⁄3 of tongue 

Communication to facial nerve (VII) 



sympathetic ganglion 


Carotid branch of 

glossopharyngeal nerve 

Pharyngeal plexus 

Pharyngeal, tonsillar and lingual 

branches of glossopharyngeal nerve 

Pharyngeal branch of vagus nerve 


Carotid sinus 

Carotid body 


External carotid artery 

31

NEUROANATOMY 

Vagus Nerve (X): Schema 

SEE ALSO PLATE 160 


Meningeal branch of vagus nerve 

Auricular branch of vagus nerve 

Pharyngotympanic (auditory) tube 

Levator veli 

palatini muscle 

Salpingopharyngeus 

muscle 

Palatoglossus muscle 

Palatopharyngeus 

muscle 

Superior pharyngeal 

constrictor muscle 

Stylopharyngeus muscle 

Middle pharyngeal constrictor muscle 

Inferior pharyngeal constrictor muscle 

Cricothyroid muscle 

Trachea 

Esophagus 

Right subclavian artery 

Right recurrent laryngeal nerve 

Heart 

Hepatic branch of anterior 

vagal trunk (in lesser omentum) 

Celiac branches from anterior 

and posterior vagal trunks 

to celiac plexus 

Celiac and superior mesenteric 

ganglia and celiac plexus 

Hepatic plexus 

Gallbladder 

and bile ducts 

Liver 

Pyloric branch 

from hepatic plexus 

Pancreas 

Duodenum 

Ascending colon 

Cecum 

Appendix 


Posterior nucleus of vagus 

nerve (parasympathetic 

and visceral afferent) 

Solitary tract nucleus (visceral 

afferents including taste) 

Spinal tract and spinal 

nucleus of trigeminal nerve 

(somatic afferent) 


(motor to pharyngeal 

and laryngeal muscles) 

Cranial root of 

accessory nerve* 

(see next plate) 


Superior ganglion of vagus nerve 

Inferior ganglion of vagus nerve 

Pharyngeal branch of vagus nerve (motor to muscles of 

palate and lower pharynx; sensory to lower pharynx) 

Communicating branch of vagus nerve to 

carotid branch of glossopharyngeal nerve 

Pharyngeal plexus 

Superior laryngeal nerve: 

Internal branch (sensory and parasympathetic) 

External branch (motor to cricothyroid muscle) 

Superior cervical cardiac branch of vagus nerve 

Inferior cervical cardiac branch of vagus nerve 

Thoracic cardiac branch of vagus nerve 

Left recurrent laryngeal nerve (motor to muscles of larynx 

except cricothyroid; sensory and parasympathetic to 

larynx below vocal folds; parasympathetic, efferent and 

afferent to upper esophagus and trachea) 

Pulmonary plexus 


Esophageal plexus 


Gastric branches of anterior vagal trunk 

(branches from posterior trunk behind stomach) 

Vagal branches (parasympathetic motor, 

secretomotor and afferent fibers) accompany 

superior mesenteric artery and its branches 

usually as far as left colic (splenic) flexure 

Small intestine 




32

Accessory Nerve (XI): Schema 

NEUROANATOMY 

SEE ALSO PLATE 28 



Cranial root of accessory nerve (joins vagus nerve 

and via recurrent laryngeal nerve supplies muscles of 

larynx, except cricothyroid)* 

Spinal root of 

accessory nerve 


Foramen 

magnum 

Superior ganglion 


Accessory nerve (XI)* 

Inferior ganglion 




Accessory nerve 

(to sternocleidomastoid 

and trapezius muscles) 

Sternocleidomastoid muscle (cut) 



Trapezius muscle 

*Recent evidence suggests that the accessory nerve lacks a cranial root and has no connection to the vagus nerve. 

Verification of this finding awaits further investigation. 



33

NEUROANATOMY 

Hypoglossal Nerve (XII): Schema 


(in hypoglossal canal) 


Intrinsic 

muscles 

of tongue 

Superior 

longitudinal 

Transverse 

and vertical 

Inferior 

longitudinal 

Styloglossus 

muscle 

Hypoglossal nucleus 

Occipital condyle 

Inferior ganglion of 

vagus nerve 

Ventral rami of 

C1, 2, 3 form 

ansa cervicalis 

of cervical plexus 


sympathetic 

ganglion 

Genioglossus 

muscle 

Geniohyoid muscle 

Hyoglossus muscle 

Superior root of 

ansa cervicalis 


Inferior root of ansa cervicalis 

Thyrohyoid muscle 

Omohyoid muscle 

(superior belly) 

Sternohyoid muscle 

Ansa cervicalis 

Internal jugular vein 


Sternothyroid muscle 

Omohyoid muscle (inferior belly) 



34

Nerves of Heart 

NEUROANATOMY 




(Conjoined sympathetic and 

vagal) superior cervical cardiac nerves 

Middle cervical 



(sympathetic) cardiac nerve 

Phrenic nerve 


(vagal) cardiac nerve 




Cervicothoracic 

(stellate) ganglion 

Ansa subclavia 

Recurrent 

laryngeal nerve 










Phrenic nerve 






Cervicothoracic 

(stellate) ganglion 


sympathetic 

cardiac nerves 


(sympathetic) cardiac nerves 

Thoracic cardiac branch 


4th thoracic 


Thoracic (sympathetic) 

cardiac branches 


3rd thoracic 


Thoracic (sympathetic) 

cardiac branches 

Thoracic cardiac 

branch of 

vagus nerve 

Recurrent laryngeal 

nerve 

Phrenic nerve (cut) 

35

NEUROANATOMY 

Autonomic Nerves and Ganglia of Abdomen 

Right sympathetic trunk 

Thoracic duct 

Right greater 

and lesser 

splanchnic 

nerves 

Right phrenic nerve 

Inferior phrenic 

arteries and plexuses 

Right greater 

and lesser 

splanchnic 

nerves 

Right suprarenal 

plexus 

Right aorticorenal 

ganglion 

Right least 

splanchnic nerve 

Right renal 

artery and plexus 

Right 

sympathetic trunk 

White and gray 

rami communicantes 

Cisterna chyli 

Gray ramus communicans 

3rd lumbar ganglion 

of sympathetic trunk 

2nd and 3rd lumbar 

splanchnic nerves 

Right ureter and plexus 

Right testicular (ovarian) 


4th lumbar splanchnic nerve 

1st sacral ganglion 

of sympathetic trunk 


Anterior, 

Posterior 

vagal trunks 

Left gastric artery 

and plexus 

Celiac ganglia 

Left greater 


Left lesser 


Splenic artery 

and plexus 

Common hepatic 


Superior mesenteric 

ganglion and plexus 

Left aorticorenal 

ganglion 

Left sympathetic 

trunk 


(aortic) plexus 

Inferior mesenteric 

ganglion 

Left colic artery 

and plexus 



Left common iliac 


Superior rectal 


Superior hypogastric 

plexus 

Internal and external 

iliac arteries and 

plexuses 

Right and left 

hypogastric nerves 

to inferior hypogastric 


Left sacral plexus 

Pelvic splanchnic 

nerves 

36

Nerves of Stomach and Duodenum 

NEUROANATOMY 

Right and left inferior phrenic arteries and plexuses 

Anterior and posterior layers of lesser omentum 

Branch from hepatic plexus to 

cardia via lesser omentum 

Right greater splanchnic 

nerve 

Hepatic branch of anterior vagal trunk 


Celiac branch of posterior vagal trunk 

Celiac branch of anterior vagal trunk 

Left gastric artery and plexus 

Vagal 

branch 

from 

hepatic 

plexus 

to 

pyloric 

part of 

stomach 


Right gastric 


Anterior gastric 

branch of anterior 

vagal trunk 

Left greater splanchnic 

nerve 

Left lesser splanchnic 

nerve 

Splenic artery and plexus 

Celiac ganglia and plexus 

Plexus on gastro-omental 

(gastroepiploic) arteries 

Superior mesenteric artery and plexus 

Plexus on inferior pancreaticoduodenal artery 

Plexus on first jejunal artery 

Plexus on anterior superior and anterior 

inferior pancreaticoduodenal arteries 

(posterior pancreaticoduodenal arteries 

and plexuses not visible in this view) 

37

NEUROANATOMY 

Nerves of Stomach and Duodenum (continued) 

Plexus on gastro-omental 

(gastroepiploic) arteries 


Right gastric 

artery and 

plexus 

Posterior gastric branch of posterior vagal trunk 

Hepatic branch of anterior vagal trunk via lesser omentum 

Branch from hepatic plexus to cardia via lesser omentum 

Right inferior phrenic artery and plexus 


Celiac branch of posterior vagal trunk 

Celiac branch of anterior vagal trunk 


Left inferior phrenic artery and plexus 


Greater, lesser and least 


Aorticorenal ganglia 

Splenic artery and plexus 

Greater, 

Lesser, 

Least 

splanchnic 

nerves 

View 

with 

stomach 

reflected 

cephalad 

Right phrenic nerve 

Phrenic ganglion 

Branch from right inferior phrenic 

plexus to cardia of stomach 

Right and left inferior phrenic 




Plexus on 

anterior superior 

and anterior inferior 

pancreaticoduodenal 

arteries 

Plexus on gastroduodenal artery 

Plexus on posterior superior 

and posterior inferior 

pancreaticoduodenal arteries 

Superior mesenteric ganglion and plexus 

Right greater, 

lesser 

and least 


Celiac ganglia 


ganglion 

Celiac branches 

of anterior 

and posterior 

vagal trunks 

Left gastric 


Left greater, 

lesser and least 


Superior mesenteric ganglion and plexus 

Left aorticorenal ganglion 

38

Nerves of Small Intestine 

NEUROANATOMY 

Recurrent branch of left inferior phrenic 

artery and plexus to esophagus 



Hepatic branch of anterior 

vagal trunk (courses in lesser 

omentum, removed here) 

Celiac branches of anterior 


Inferior phrenic arteries and plexuses 



Greater splanchnic nerves 

Right gastric artery and plexus (cut) 


Gastroduodenal artery and plexus 

Lesser splanchnic nerves 

Least splanchnic nerves 

Aorticorenal ganglia 


Intermesenteric (aortic) plexus 

Inferior pancreaticoduodenal 




Middle colic artery and plexus (cut) 

Right colic artery and plexus 

Ileocolic artery and plexus 



Peritoneum (cut edge) 

Mesenteric branches 

Mesoappendix (contains 

appendicular artery and 

nerve plexus) 

39

NEUROANATOMY 

Nerves of Large Intestine 

Anterior vagal trunk and hepatic branch 


Celiac branches of anterior 


Right inferior phrenic artery and plexus 

Right greater 



Right lesser and 

least splanchnic 

nerves 


ganglion 

Superior 

mesenteric 

ganglion 

Middle colic 

artery 

and plexus 

Inferior 

pancreaticoduodenal 

arteries 

and plexuses 

Right colic 

artery 

and plexus 

Ileocolic 

artery 

and plexus 

Cecal and 

appendicular 

arteries 

and plexuses 

Right internal 

iliac artery 

and plexus (cut) 

Sacral sympathetic trunk 

Right sacral plexus 


Middle rectal artery and plexus 

Right inferior hypogastric 



Rectal plexus 

Urinary bladder 

Marginal artery and plexus 

Esophagus 

Left inferior phrenic 


Left gastric artery 

and plexus 

Left greater 

splanchnic 

nerve 

Left suprarenal 

plexus 

Left lesser and 

least splanchnic 

nerves 

Left aorticorenal 

ganglion 

Left renal artery 

and plexus 

1st left lumbar 


Left lumbar 

sympathetic trunk 



Left colic artery 

and plexus 

Inferior 

mesenteric 

ganglion, artery 

and plexus 

Sigmoid 

arteries 

and plexuses 

Superior 

hypogastric 

plexus 

Superior 

rectal 

artery 

and plexus 


hypogastric 

nerves 

Rectosigmoid 

artery and 

plexus 

Nerves from inferior hypogastric (pelvic) 

plexuses to sigmoid colon, descending 

colon and left colic (splenic) flexure 

40

Nerves of Kidneys, Ureters and Urinary Bladder 

NEUROANATOMY 



Greater splanchnic nerve 


Lesser splanchnic nerve 


Least splanchnic nerve 


Renal plexus and ganglion 

2nd lumbar splanchnic nerve 

Renal and upper ureteric branches 

from intermesenteric plexus 


Testicular (ovarian) artery and plexus 

Inferior mesenteric ganglion 

Sympathetic trunk and ganglion 

Middle ureteric branch 


Sacral splanchnic nerves 

(branches from upper sacral 

sympathetic ganglia to 

hypogastric plexus) 

Gray ramus communicans 


Sacral plexus 

Pudendal nerve 


Inferior hypogastric (pelvic) plexus 

with periureteric loops and 

branches to lower ureter 

Rectal plexus 



41

NEUROANATOMY 

Nerves of Pelvic Viscera: Male 



and 

Celiac branch 

Inferior phrenic arteries and plexuses 

Left gastric artery and gastric plexus 

Celiac ganglia, plexus and trunk 

Left aorticorenal ganglion 


Superior mesenteric artery and plexus 


Inferior mesenteric ganglion, 


Ureter and ureteric plexus 


Superior rectal artery and plexus 


Nerve from inferior 

hypogastric plexus 

to sigmoid and descending 

colon (parasympathetic) 

Sacral splanchnic nerves 

(sympathetic) 

Inferior hypogastric 


Obturator nerve 

and artery 

Ductus deferens 

and plexus 


Rectal plexus 


Cavernous nerves 

of penis 

T10 spinal nerve (anterior ramus) 

White and gray rami communicantes 

Greater 

Lesser 

Least 

Gray 

White 

Lumbosacral trunk 

Diaphragm 


Sympathetic trunk and ganglia 

5th lumbar splanchnic nerve 

L5 spinal nerve (anterior ramus) 


S1 spinal nerve 

(anterior ramus) 

Sacral plexus 

Pudendal nerve 

Levator ani muscle 

Splanchnic 

nerves 

Left renal artery 

and plexus 

L1 spinal nerve 

(anterior ramus) 

Rami 

communicantes 

1st, 2nd, 3rd lumbar splanchnic nerves 

Pelvic splanchnic 

nerves 

(parasympathetic) 

Piriformis muscle 

Gluteus maximus 

muscle and sacrotuberous 

ligament 

(Ischio-)coccygeus 

muscle and 

sacrospinous ligament 

Inferior anal (rectal) nerve 

Perineal nerve 

Dorsal nerve of penis 

Posterior scrotal nerves 

42

Nerves of Pelvic Viscera: Female 

NEUROANATOMY 


and L2 ganglion 

Abdominal aorta 

Inferior vena cava 

Peritoneum 

White and 

gray rami 

communicantes 

Lumbar 

splanchnic 

nerves 

Extraperitoneal 

(subserous) 

fascia 

Common 

iliac vessels 

and plexus 

Ureter 



Gray rami 

communicantes 

L5 spinal 

nerve 

Ovarian artery 

and plexus 

Superior 

hypogastric 

plexus 

Sacral 

promontory 

Right 

hypogastric 

nerve (cut) 

Right and 

left sacral 

sympathetic 

trunks and 

ganglia 

Piriformis 

muscle 

Sacral 

splanchnic 

nerves 

(sympathetic) 

Pudendal 

nerve 

S2 

S3 

S4 

S5 

S1 

Superior 

hypogastric 

plexus 

Common 

iliac artery 

and plexus 

Ureter 

Internal 

iliac artery 

and plexus 

External 

iliac artery 

and plexus 

Left hypogastric nerve 

Inferior hypogastric (pelvic) plexus 

Uterine (fallopian) tube 

Ovary 


hypogastric nerves 

Uterus 

Sigmoid 

colon 

Right sympathetic trunk 

Pelvic 

splanchnic 

nerves 

(parasympathetic) 

Symphyseal surface of pubis 



(Ischio-)coccygeus muscle 

Uterovaginal plexus 

Rectal plexus 

Uterus (retracted) 

Rectum (retracted) 

43

NEUROANATOMY 

Median Nerve 

Anterior view 

Note: Only muscles innervated by median nerve shown 

Musculocutaneous nerve 

Median nerve (C5, 6, 7, 8, T1) 

Inconstant contribution 

Pronator teres muscle (humeral head) 


Flexor carpi radialis muscle 

Palmaris longus muscle 

Pronator teres muscle (ulnar head) 

Flexor digitorum superficialis muscle 

(turned up) 

Medial 

Posterior 

Lateral 

Medial cutaneous 

nerve of arm 

Medial cutaneous 

nerve of forearm 

Axillary nerve 

Radial nerve 

Ulnar nerve 

Cords of 

brachial 

plexus 

Flexor digitorum profundus muscle 

(lateral part supplied by median 

[anterior interosseous] nerve; 

medial part supplied by ulnar nerve) 

Anterior interosseous nerve 

Flexor pollicis longus muscle 

Pronator quadratus muscle 

Palmar branch of median nerve 

Cutaneous 

innervation 

Thenar 

muscles 

Abductor pollicis brevis 

Opponens pollicis 

Superficial head of 

flexor pollicis brevis 

(deep head 

supplied by 

ulnar nerve) 

1st and 2nd 

lumbrical muscles 

Communicating branch 

of median nerve with 

ulnar nerve 

Common palmar 

digital nerves 

Palmar view 

Dorsal branches to 

dorsum of middle and 

distal phalanges 

Proper palmar 


Posterior (dorsal) view 

44

Ulnar Nerve 

NEUROANATOMY 

Anterior view 

Note: Only muscles innervated 

by ulnar nerve shown 

Ulnar nerve (C7, 8, T1) 

(no branches above elbow) 


Medial epicondyle 

Cutaneous 

innervation 


(behind condyle) 

Flexor digitorum profundus 

muscle (medial part only; 

lateral part supplied by 

anterior interosseous 

branch of median nerve) 

Palmar view 

Flexor carpi ulnaris muscle 

(drawn aside) 

Posterior 

(dorsal) view 

Dorsal branch of ulnar nerve 

Palmar branch 

Flexor pollicis brevis muscle 

(deep head only; superficial 

head and other thenar muscles 

supplied by median nerve) 

Superficial branch 

Deep branch 

Adductor pollicis muscle 

Palmaris brevis 

Abductor digiti minimi 

Flexor digiti minimi brevis 

Opponens digiti minimi 

Hypothenar muscles 

Common palmar digital nerve 

Communicating branch of median nerve with 

ulnar nerve 

Palmar and dorsal interosseous muscles 

3rd and 4th lumbrical muscles (turned down) 

Proper palmar digital nerves 

(dorsal digital nerves are from dorsal branch) 

Dorsal branches to dorsum of middle and distal phalanges 

45

NEUROANATOMY 

Radial Nerve in Arm and Nerves of Posterior Shoulder 

Dorsal scapular nerve (C5) 


Supraspinatus muscle 

Suprascapular nerve (C5, 6) 

Levator scapulae 

muscle (supplied 

also by branches 

from C3 and C4) 

Deltoid muscle 

Teres minor muscle 

Axillary nerve (C5, 6) 

Rhomboid 

minor muscle 

Rhomboid 

major muscle 

Superior lateral 

cutaneous nerve of arm 

Radial nerve 

(C5, 6, 7, 8, T1) 


Inferior lateral 

cutaneous nerve of arm 

Infraspinatus muscle 

Teres major muscle 

Lower subscapular nerve (C5, 6) 

Posterior cutaneous nerve of arm 

(branch of radial nerve in axilla) 

Triceps brachii muscle 

Long head 

Lateral head 

Medial head 

Posterior cutaneous 


Lateral intermuscular 

septum 

Brachialis muscle (lateral 

part; remainder of muscle 

supplied by musculocutaneous 

nerve) 

Brachioradialis muscle 

Triceps brachii tendon 

Medial epicondyle 

Olecranon 

Anconeus muscle 

Extensor digitorum muscle 

Extensor carpi radialis 

longus muscle 

Extensor carpi 

radialis brevis 

muscle 

Extensor carpi ulnaris muscle 

46

Radial Nerve in Forearm 

NEUROANATOMY 

Radial nerve (C5, 6, 7, 8, T1) 


Superficial (terminal) branch 

Deep (terminal) branch 

Lateral epicondyle 


Anconeus muscle 

Brachioradialis muscle 

Extensor carpi radialis longus muscle 

Supinator muscle 

Extensor carpi radialis brevis muscle 

Extensor carpi ulnaris muscle 

Extensor digitorum muscle and 

extensor digiti minimi muscle 

Extensor indicis muscle 

Extensor-supinator 

group of muscles 

Extensor pollicis longus muscle 

Abductor pollicis longus muscle 

Extensor pollicis brevis muscle 

Posterior interosseous nerve 

(continuation of deep branch of 

radial nerve distal to supinator muscle) 

Superficial branch of radial nerve 

From axillary nerve 

Superior lateral 

cutaneous nerve 

of arm 

Inferior lateral 


of arm 

From radial nerve 


nerve of arm 



Superficial branch of 

radial nerve and dorsal 

digital branches 

Dorsal digital nerves 

Cutaneous innervation from 

radial and axillary nerves 

47

NEUROANATOMY 

Sciatic Nerve and Posterior Cutaneous Nerve of Thigh 


nerve of thigh 

(S1, 2, 3) 

Inferior cluneal nerves 

Perineal branches 

Greater sciatic foramen 

Sciatic nerve (L4, 5, S1, 2, 3) 

Tibial division 

of sciatic nerve 

Common fibular (peroneal) 

division of sciatic nerve 

Long head (cut) of 

biceps femoris muscle 

Short head of 

biceps femoris muscle 

Cutaneous innervation 

Adductor magnus muscle 

(also partially supplied 

by obturator nerve) 

Semitendinosus muscle 

Semimembranosus muscle 

Long head (cut) 

of biceps femoris 

muscle 

Common fibular 

(peroneal) nerve 

Tibial nerve 


Plantaris muscle 

Articular 

branch 

Lateral sural 


Posterior 


of thigh 

Medial sural 


Gastrocnemius muscle 

Sural nerve 

Soleus muscle 

Tibial nerve 

Medial 

calcaneal branches 

Medial and lateral 

plantar nerves 

Sural 

communicating 

branch 

Lateral calcaneal 

branches 

Lateral dorsal 


From sciatic 

nerve 



via lateral sural 


Medial sural 


Superficial fibular 


Sural nerve 

Tibial nerve 

via medial 

calcaneal 

branches 

48

Tibial Nerve 

NEUROANATOMY 

Tibial nerve 

(L4, 5, S1, 2, 3) 

Medial sural 

cutaneous nerve (cut) 

Articular branches 

Plantaris muscle 

Gastrocnemius 

muscle (cut) 

Nerve to popliteus muscle 

Popliteus muscle 

Interosseous nerve of leg 

Common fibular (peroneal) nerve 

Lateral sural cutaneous nerve (cut) 

From 

tibial nerve 


Medial calcaneal 

branches 

(S1, 2) 

Medial 

plantar nerve 

(L4, 5) 

Lateral 

plantar nerve 

(S1, 2) 

Saphenous nerve 

(L3, 4) 

Sural nerve 

(S1, 2) via 

lateral calcaneal 

and lateral dorsal 

cutaneous 

branches 

Cutaneous innervation of sole 

Soleus muscle (cut and 

partly retracted) 

Flexor digitorum 

longus muscle 

Tibialis posterior muscle 

Flexor hallucis 

longus muscle 

Sural nerve (cut) 

Lateral calcaneal branch 

Medial 

calcaneal branch 

Flexor retinaculum (cut) 

Lateral dorsal 


Flexor 

retinaculum 

(cut) 

Tibial 

nerve 

Medial 

calcaneal 

branch 

Medial plantar 

nerve 

Flexor digitorum 

brevis muscle 

and nerve 

Abductor hallucis 

muscle and nerve 

Flexor hallucis 

brevis muscle 

and nerve 

1st lumbrical 

muscle and 

nerve 

Common 

plantar 

digital 

nerves 

Proper 

plantar 

digital 

nerves 

Lateral calcaneal 

branch of sural nerve 

Lateral plantar 

nerve 

Nerve to abductor 

digiti minimi muscle 

Quadratus plantae 

muscle and nerve 

Abductor digiti 

minimi muscle 

Deep branch to 

interosseous 

muscles, 

2nd, 3rd and 4th 

lumbrical muscles 

and 

Adductor hallucis 

muscle 

Superficial 

branch to 

4th interosseous 

muscle 

and 

Flexor digiti minimi 

brevis muscle 

Common and 

Proper plantar 


Note: Articular branches not shown 

49

NEUROANATOMY 

Common Fibular (Peroneal) Nerve 



(phantom) 

Biceps femoris tendon 

Common fibular (peroneal) 

nerve (L4, 5, S1, 2) 

Lateral sural cutaneous nerve (phantom) 

Articular branches 

Recurrent articular nerve 

Extensor digitorum longus muscle (cut) 

Head of fibula 

Fibularis (peroneus) 

longus muscle (cut) 

Deep fibular (peroneal) nerve 

Tibialis anterior muscle 



Cutaneous innervation 

Branches of lateral 

sural cutaneous nerve 

Extensor digitorum 

longus muscle 


longus muscle 


brevis muscle 

Extensor hallucis 

longus muscle 

Lateral sural 


Medial dorsal cutaneous nerve 



Intermediate dorsal 


Inferior extensor 

retinaculum (partially cut) 

Lateral dorsal cutaneous nerve 

(branch of sural nerve) 

Lateral branch of 

deep fibular 

(peroneal) nerve to 

Extensor hallucis brevis 

and 

Extensor digitorum brevis 

muscles 

Medial branch of 

deep fibular 


Deep 

fibular 

(peroneal) 

nerve 

Dorsal digital nerves 

Sural nerve 

via lateral dorsal 

cutaneous branch 

50

Part 2 Neurophysiology 

Organization of the Brain: Cerebrum. . . . . . . 52 

Organization of the Brain: Cell Types. . . . . . . 53 

Blood-Brain Barrier . . . . . . . . . . . . . . . . . . . . . 54 

Synaptic Transmission: 

Morphology of Synapses . . . . . . . . . . . . . . . 55 


Neuromuscular Junction . . . . . . . . . . . . . . . 56 


Visceral Efferent Endings . . . . . . . . . . . . . . . 57 


Inhibitory Mechanisms . . . . . . . . . . . . . . . . 58 


Chemical Synaptic Transmission . . . . . . . . . 59 


Temporal and Spatial Summation . . . . . . . . 60 

Cerebrospinal Fluid (CSF): 

Brain Ventricles and CSF Composition . . . . 61 

Cerebrospinal Fluid (CSF): 

Circulation of CSF . . . . . . . . . . . . . . . . . . . . 62 

Spinal Cord: Ventral Rami. . . . . . . . . . . . . . . . 63 

Spinal Cord: Membranes and Nerve Roots . . 64 

Peripheral Nervous System . . . . . . . . . . . . . . . 65 

Autonomic Nervous System: Schema. . . . . . . 66 

Autonomic Nervous System: 

Cholinergic and Adrenergic Synapses . . . . . 67 

Hypothalamus . . . . . . . . . . . . . . . . . . . . . . . . . 68 

Limbic System . . . . . . . . . . . . . . . . . . . . . . . . . 69 

The Cerebral Cortex . . . . . . . . . . . . . . . . . . . . 70 

Descending Motor Pathways . . . . . . . . . . . . . 71 

Cerebellum: Afferent Pathways. . . . . . . . . . . . 72 

Cerebellum: Efferent Pathways . . . . . . . . . . . . 73 

Cutaneous Sensory Receptors. . . . . . . . . . . . . 74 

Cutaneous Receptors: 

Pacinian Corpuscle. . . . . . . . . . . . . . . . . . . . 75 

Proprioception and Reflex Pathways: I . . . . . . 76 

Proprioception and Reflex Pathways: II . . . . . 77 

Proprioception and Reflex Pathways: III . . . . 78 

Proprioception and Reflex Pathways: IV. . . . . 79 

Sensory Pathways: I. . . . . . . . . . . . . . . . . . . . . 80 

Sensory Pathways: II . . . . . . . . . . . . . . . . . . . . 81 

Sensory Pathways: III. . . . . . . . . . . . . . . . . . . . 82 

Visual System: Receptors. . . . . . . . . . . . . . . . . 83 

Visual System: Visual Pathway . . . . . . . . . . . . 84 

Auditory System: Cochlea . . . . . . . . . . . . . . . . 85 

Auditory System: Pathways . . . . . . . . . . . . . . . 86 

Vestibular System: Receptors . . . . . . . . . . . . . 87 

Vestibular System: Vestibulospinal Tracts. . . . 88 

Gustatory (Taste) System: Receptors . . . . . . . 89 

Gustatory (Taste) System: Pathways . . . . . . . . 90 

Olfactory System: Receptors . . . . . . . . . . . . . . 91 

Olfactory System: Pathway . . . . . . . . . . . . . . . 92

NEUROPHYSIOLOGY 

Organization of the Brain: Cerebrum 

Precentral sulcus 

Central sulcus (Rolando) 

Precentral gyrus 

Postcentral gyrus 

Postcentral sulcus 

Superior parietal lobule 

Inferior parietal lobule 

Supramarginal gyrus 

Angular gyrus 

Parietooccipital 

sulcus 

Frontal pole 

Occipital pole 


Lateral sulcus 

(Sylvius) 

Temporal pole 

Superior temporal gyrus 

Middle temporal gyrus 

Inferior temporal gyrus 

Frontal lobe 

Parietal lobe 

Temporal lobe 

Occipital lobe 

Insula (island of Reil) 

© 

FIGURE 2.1 

ORGANIZATION OF THE BRAIN: CEREBRUM • 

The cerebral cortex represents the highest center for sensory and 

motor processing. In general, the frontal lobe processes motor, 

visual, speech, and personality modalities. The parietal lobe 

processes sensory information; the temporal lobe, auditory and 

memory modalities; and the occipital lobe, vision. The cerebellum 

coordinates smooth motor activities and processes muscle position. 

The brainstem (medulla, pons, midbrain) conveys motor and sensory 

information and mediates important autonomic functions. The spinal 

cord receives sensory input from the body and conveys somatic and 

autonomic motor information to peripheral targets (muscles, viscera). 

52

Organization of the Brain: Cell Types 


Multipolar (pyramidal) 

cell of cerebral 

motor cortex 

Astrocyte 

Motor 

endplate 

Multipolar somatic 

motor cell of nuclei 

of cranial nn. 

Multipolar cell 

of lower brain 

motor centers 

Oligodendrocyte 

Corticospinal 

(pyramidal) fiber 

Axodendritic ending 

Axosomatic ending 

Axoaxonic ending 

Multipolar somatic 

motor cell of 

anterior horn 

of spinal cord 

Collateral 

Striated 

(somatic) 

muscle 

Renshaw interneuron 

(feedback) 

Myelinated somatic motor 

fiber of spinal nerve 

Interneurons 

Blood vessel 

Interneuron 

Astrocyte 

Multipolar visceral 

motor (autonomic) 

cell of spinal cord 

Autonomic preganglionic 

(sympathetic or parasympathetic) 

nerve fiber 

Myelin sheath 

Autonomic postganglionic 

neuron of sympathetic or 

parasympathetic ganglion 

Satellite cells 

Unmyelinated nerve fiber 

Schwann cells 

Bipolar cell of cranial n. 

Unipolar cell of 

sensory ganglia of 

cranial nn. 


Schwann cell 

Free nerve endings 

(unmyelinated fibers) 

Encapsulated ending 

Specialized ending 

Muscle spindle 

Unipolar sensory cell 

of dorsal spinal 

root ganglion 


Myelinated afferent 

fiber of spinal nerve 

Myelin sheath 

Red: Motor neuron 

Blue: Sensory neuron 

Purple: Interneuron 

Gray: Glial and 

neurilemmal cells 

and myelin 

Note: Cerebellar cells 

not shown here 

Myelin sheath 

Schwann cells 

Motor endplate with 

Schwann cell cap 

Striated 

(voluntary) 

muscle 

Endings on 

cardiac muscle 

or nodal cells 

Beaded 

varicosities 

and endings on 

smooth muscle 

and gland cells 

Unmyelinated fibers 


Encapsulated ending 

Muscle spindle 

© 

FIGURE 2.2 

ORGANIZATION OF THE BRAIN: CELL TYPES • 

Neurons form the functional cellular units responsible for 

communication, and throughout the nervous system, they are 

characterized by their distinctive size and shapes (e.g., bipolar, 

unipolar, multipolar). Supporting cells include the neuroglia 

(e.g., astrocytes, oligodendrocytes), satellite cells, and other specialized 

cells that optimize neuronal function, provide maintenance 

functions, or protect the nervous system. 

53


Blood-Brain Barrier 

Tight 

junction 

proteins 

Cell 

membrane 

Basement 

membrane 

Cytoplasm 

Red 

blood 

cell 

Capillary 

lumen 

Astrocyte 

foot processes 

Tight 

junction 

Capillary 

endothelial 

cell 

Astrocyte 

© 

FIGURE 2.3 

BLOOD-BRAIN BARRIER • 

The blood-brain barrier (BBB) is the cellular interface between the 

blood and the central nervous system (CNS; brain and spinal cord). 

It serves to maintain the interstitial fluid environment to ensure 

optimal functionality of the neurons. This barrier consists of the 

capillary endothelial cells with an elaborate network of tight junctions 

and astrocytic foot processes that abut the endothelium and 

its basement membrane. The movement of large molecules and 

54 

other substances (including many drugs) from the blood to the 

interstitial space of the CNS is restricted by the BBB. CNS endothelial 

cells also exhibit a low level of pinocytotic activity across the 

cell, so specific carrier systems for the transport of essential substrates 

of energy and amino acid metabolism are characteristic of 

these cells. The astrocytes help transfer important metabolites from 

the blood to the neurons and also remove excess K and neurotransmitters 

from the interstitial fluid.

Synaptic Transmission: Morphology of Synapses 


Dendrite 

Node 

Axon 

Dendrites 

Myelin sheath 

Numerous boutons (synaptic knobs) 

of presynaptic neurons terminating 

on a motor neuron and its dendrites 

Enlarged section 

of bouton 

Axolemma 

Mitochondria 

Glial process 

Synaptic vesicles 

Synaptic cleft 

Presynaptic membrane 

(densely staining) 

Postsynaptic membrane 

(densely staining) 

Postsynaptic cell 

Axon (axoplasm) 

© 

FIGURE 2.4 

MORPHOLOGY OF SYNAPSES • 

Neurons communicate with each other and with effector targets at 

specialized regions called synapses. The top figure shows a typical 

motor neuron that receives numerous synaptic contacts on its cell 

body and associated dendrites. Incoming axons lose their myelin 

sheaths, exhibit extensive branching, and terminate as synaptic 

boutons (synaptic terminals or knobs) on the motor neuron. The 

lower figure shows an enlargement of one such synaptic bouton. 

Chemical neurotransmitters are contained in synaptic vesicles, 

which can fuse with the presynaptic membrane, release the transmitters 

into the synaptic cleft, and then bind to receptors situated 

in the postsynaptic membrane. This synaptic transmission results in 

excitatory, inhibitory, or modulatory effects on the target cell. 

55


Synaptic Transmission: Neuromuscular Junction 

Structure of Neuromuscular Junction 

Active zone 

Schwann cell process 

Acetylcholine 

receptor sites 

Myelin sheath 

Neurilemma 

Axoplasm 

Schwann cell 

Mitochondria 

Basement membrane 

Nucleus of Schwann cell 

Presynaptic membrane 

Active zone 

Synaptic vesicles 

Synaptic trough 


Sarcolemma 

Nucleus of 

muscle cell 

Myofibrils 


Postsynaptic 

membrane 

Junctional fold 

Sarcoplasm 

Acetylcholine receptor sites 

© 

FIGURE 2.5 

STRUCTURE OF THE NEUROMUSCULAR JUNCTION • 

Motor axons that synapse on skeletal muscle form expanded terminals 

called neuromuscular junctions (motor endplates). The motor 

axon loses its myelin sheath and expands into a Schwann 

cell–invested synaptic terminal that resides within a trough in the 

muscle fiber. Acetylcholine-containing synaptic vesicles accumulate 

adjacent to the presynaptic membrane and, when appropriately 

stimulated, release their neurotransmitter into the synaptic 

cleft. The transmitter then binds to receptors that mediate depolarization 

of the muscle sarcolemma and initiate a muscle action 

potential. A single muscle fiber has only one neuromuscular junction, 

but a motor axon can innervate multiple muscle fibers. 

56

Synaptic Transmission: Visceral Efferent Endings 


Visceral Efferent Endings 

A. Smooth muscle 

Smooth muscle cells (cut) 

Schwann cell cap enclosing 

nerve axons 

Mucous cells 

Schwann cell 

cap enclosing 

nerve axons 

B. Gland (submandibular) 

Sympathetic terminal 

ending 

Varicosity 

Schwann 

cell cap 

⎧ 

⎪⎪⎨⎪⎪⎩ 

⎧ 

⎪⎪⎨⎪⎪⎩ 

⎧ 

⎪⎪⎨⎪⎪⎩ 

Axon 

C. Neurosecretory 

(posterior pituitary) 

Pituicyte processes 

Axon 

Schwann cell cap 

Smooth muscle cells 

Varicosities 

Terminal endings 

Serous cells 

Parasympathetic 

terminal ending 

Schwann cell 

cap enclosing 

nerve axons 

Varicosity 

Capillary 

Endothelium 

Mast cell 

Fibroblast 

Neurosecretory 

vesicles 

Collagen space 


© 

FIGURE 2.6 

VISCERAL EFFERENT ENDINGS • 

Neuronal efferent endings on smooth muscle (A) and glands (B 

and C) exhibit unique endings unlike the presynaptic and postsynaptic 

terminals observed in neuronal and neuromuscular junction 

synapses. Rather, neurotransmitter substances are released 

into interstitial spaces (A and B) or into the bloodstream (C, neurosecretion) 

from expanded nerve terminal endings. This arrangement 

allows for the stimulation of numerous target cells over a 

wide area. Not all smooth muscle cells are innervated. They are 

connected to adjacent cells by gap junctions and can therefore 

contract together with the innervated cells. 

57


Synaptic Transmission: Inhibitory Mechanisms 

E 

(Excitatory 

fiber) 

I 

(Inhibitory 

fiber) 

E 

(Excitatory 

fiber) 

Motor 

neuron 

Motor 

neuron 

Axon 

I 

(Inhibitory 

fiber) 

Axon 

A. Only E fires 

90-mV spike 

in E terminal 

mV 

20 

90 mV A′. Only E fires 

mV 

EPSP in 

motor neuron 

70 

60 

70 

EPSP in 

motor 

neuron 

60 

70 

B. Only I fires 

Long-lasting 

partial 

depolarization 

in E terminal 

No response in 

motor neuron 

60 

70 

70 

B′. Only I fires 

Motor 

neuron 

hyperpolarized 

70 

80 

C. I fires before E 

Partial 

depolarization 

of E terminal 

reduces spike 

to 80 mV, thus 

releasing less 

transmitter 

substance 

Smaller EPSP in 

motor neuron 

20 

70 

60 

70 

80 mV 

C′. I fires before E 

Depolarization 

of motor 

neuron less 

than if only 

E fires 

60 

70 

80 

© 

FIGURE 2.7 

SYNAPTIC INHIBITORY MECHANISMS • 

Inhibitory synapses modulate neuronal activity. Illustrated here is presynaptic inhibition (left panel) and postsynaptic inhibition (right 

panel) at a motor neuron. 

58

Synaptic Transmission: Chemical Synaptic Transmission 


Excitatory 

⎧ 

⎪⎪⎨⎪⎪⎩ 

⎧ 

⎪⎪⎨⎪⎪⎩ 

Synaptic 

vesicles 

in synaptic 

bouton 

Presynaptic 

membrane 

Inhibitory 

 

 

 

 

 

 

Na Current 

K 

 

 

 

 

Transmitter 

substances 


Postsynaptic 

membrane 

 

 

 

 

 

 

Cl 

 

 

 

 

When impulse reaches excitatory synaptic 

bouton, it causes release of a transmitter 

substance into synaptic cleft. This increases 

permeability of postsynaptic membrane to 

Na and K . More Na moves into postsynaptic 

cell than K moves out, due to greater 

electrochemical gradient 

At inhibitory synapse, transmitter substance released 

by an impulse increases permeability of 

the postsynaptic membrane to Cl . K moves 

out of post-synaptic cell but no net flow of Cl 

occurs at resting membrane potential 

Synaptic bouton 

Resultant net ionic current flow is in a direction 

that tends to depolarize postsynaptic cell. 

If depolarization reaches firing threshold, an 

impulse is generated in postsynaptic cell 

Potential (mV) 

65 

Potential 

70 0 4 8 12 16 

msec 

Current flow and potential change 

Resultant ionic current flow is in direction that tends to 

hyperpolarize postsynaptic cell. This makes depolarization 

by excitatory synapses more difficult—more depolarization 

is required to reach threshold 

msec 

12 16 

75 

Current 

Potential 

Potential (mV)70 0 4 8 

Current flow and potential change 

© 

FIGURE 2.8 

CHEMICAL SYNAPTIC TRANSMISSION • 

Chemical synaptic transmission between neurons may be excitatory 

or inhibitory. During excitation (left column), a net increase in 

the inward flow of Na compared with the outward flow of K 

results in a depolarizing potential change (excitatory postsynaptic 

potential [EPSP]) that drives the postsynaptic cell closer to its 

threshold for an action potential. During inhibition (right column), 

the opening of K and Cl channels drives the membrane potential 

away from threshold (hyperpolarization) and decreases the probability 

that the neuron will reach threshold (inhibitory postsynaptic 

potential [IPSP]) for an action potential. 

59


Synaptic Transmission: Temporal and Spatial Summation 

Temporal and Spatial Summation 

of Excitation and Inhibition 

Excitatory fibers 

mV 


mV 

–70 

–70 

Axon 

Axon 

Inhibitory fibers 

A. Resting state: motor nerve cell shown with synaptic boutons of 

excitatory and inhibitory nerve fibers ending close to it 


B. Partial depolarization: impulse from one excitatory fiber has 

caused partial (below firing threshold) depolarization of motor 

neuron 


mV 

–70 


mV 

–70 


Axon 

C. Temporal excitatory summation: a series of impulses in one 

excitatory fiber together produce a suprathreshold depolarization 

that triggers an action potential 


Axon 

D. Spatial excitatory summation: impulses in two excitatory fibers 

cause two synaptic depolarizations that together reach firing 

threshold triggering an action potential 


mV 


mV 

–70 

–70 

Axon 

Axon 


E. Spatial excitatory summation with inhibition: impulses from 

two excitatory fibers reach motor neuron but impulses from 

inhibitory fiber prevent depolarization from reaching threshold 


E. (continued): motor neuron now receives additional excitatory 

impulses and reaches firing threshold despite a simultaneous 

inhibitory impulse; additional inhibitory impulses might still 

prevent firing 

© 

CHART 2.1 

SUMMARY OF SOME NEUROTRANSMITTERS AND WHERE WITHIN THE CENTRAL AND PERIPHERAL NERVOUS 

SYSTEM THEY ARE FOUND 

Transmitter 

Acetylcholine 

Biogenic amines 

Norepinephrine 

Dopamine 

Serotonin 

Amino acids 

-Aminobutyric 

acid (GABA) 

Glutamate 

Purines 

Adenosine 

Adenosine 

triphosphate (ATP) 

Location 

Neuromuscular junction, autonomic endings 

and ganglia, CNS 

Sympathetic endings, CNS 

CNS 

CNS, GI tract 

CNS 

CNS 

CNS 

CNS 

Transmitter 

Gas 

Nitric oxide 

Peptides 

-Endorphins 

Enkephalins 

Antidiuretic 

hormone 

Pituitary-releasing 

hormones 

Somatostatin 

Neuropeptide Y 

Vasoactive 

intestinal peptide 

Location 

CNS, GI tract 

CNS, GI tract 

CNS 

CNS (hypothalamus/posterior 

pituitary) 

CNS (hypothalamus/anterior 

pituitary) 

CNS, GI tract 

CNS 

CNS, GI tract 

CNS, Central nervous system; GI, gastrointestinal. 

FIGURE 2.9 

TEMPORAL AND SPATIAL SUMMATION • 

Neurons receive multiple excitatory and inhibitory inputs. Temporal 

summation occurs when a series of subthreshold impulses in 

one excitatory fiber produces an action potential in the postsynaptic 

cell (panel C). Spatial summation occurs when subthreshold 

impulses from two or more different fibers trigger an action potential 

(panel D). Both temporal and spatial summation can be modulated 

by simultaneous inhibitory input (panel E). Inhibitory and 

excitatory neurons use a wide variety of neurotransmitters, some of 

which are summarized here. 

60

Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition 


Left lateral phantom view 

Right lateral ventricle 

Frontal (anterior) horn 

Central part 

Temporal (inferior) horn 


Left 

lateral 

ventricle 


4th ventricle 

Left lateral aperture 

(foramen of Luschka) 

Left interventricular 


3rd ventricle 

Left lateral recess 

Median aperture 

(foramen of Magendie) 


© 

CHART 2.2 

CSF COMPOSITION 

CSF 

Blood Plasma 

Na (mEq/L) 140–145 135–147 

K (mEq/L) 3 3.5–5.0 

Cl − (mEq/L) 115–120 95–105 

HCO 3− (mEq/L) 20 22–28 

Glucose (mg/dL) 50–75 70–110 

Protein (g/dL) 0.05–0.07 6.0–7.8 

pH 7.3 7.35–7.45 

FIGURE 2.10 

BRAIN VENTRICLES AND CSF COMPOSITION • 

CSF circulates through the four brain ventricles (two lateral ventricles 

and a third and fourth ventricle) and in the subarachnoid 

space surrounding the brain and spinal cord. The electrolyte composition 

of the CSF is regulated by the choroid plexus, which 

secretes the CSF. Importantly, the CSF has a lower [HCO 3 ] than 

plasma and therefore a lower pH. This allows small changes in 

blood PCO 2 to cause changes in CSF pH, which in turn regulates 

the rate of respiration (see Chapter 5). 

61


Cerebrospinal Fluid (CSF): Circulation of CSF 

Dura mater 

Choroid plexus of lateral 

ventricle (phantom) 

Cistern of corpus callosum 



Arachnoid granulations 

Arachnoid 



Choroid plexus of 3rd ventricle 


Lateral aperture (foramen of Luschka) 


Dura mater 

Median aperture 

(foramen of Magendie) 

Arachnoid 



© 

FIGURE 2.11 

CIRCULATION OF CEREBROSPINAL FLUID • 

CSF circulates through the four brain ventricles (two lateral ventricles 

and a third and fourth ventricle) and in the subarachnoid 

space surrounding the brain and spinal cord. Most of the CSF is 

reabsorbed into the venous system through the arachnoid granulations 

and through the walls of the capillaries of the central nervous 

system and pia mater. 

62

Spinal Cord: Ventral Rami 


Base of skull 



T1 spinal nerve 

C1 vertebra (atlas) 

Cervical plexus 

Brachial plexus 

Intercostal 

nerves 

1st rib 

Spinal dura mater 

Filaments 

of spinal 

nerve roots 

(T7 and T8) 

T12 spinal 

nerve 

12th rib 

L1 

vertebra 


L1 spinal nerve 

Cauda equina 

S1 spinal nerve 

Sacrum (cut away) 

Termination of 

dural sac 


Lumbar plexus 

L5 vertebra 

Sacral plexus 

Sciatic nerve 

Coccyx 

© 

FIGURE 2.12 

SPINAL CORD AND VENTRAL RAMI IN SITU • 

The spinal cord gives rise to 31 pairs of spinal nerves that distribute 

segmentally to the body. These nerves are organized into plexuses 

that distribute to the neck (cervical plexus), upper limb (brachial 

plexus), and pelvis and lower limb (lumbosacral plexus). Motor 

fibers of these spinal nerves innervate skeletal muscle, and sensory 

fibers convey information back to the central nervous system from 

the skin, skeletal muscles, and joints. 

63


Spinal Cord: Membranes and Nerve Roots 


Ventral root of spinal nerve 

Dorsal root of spinal nerve 

Spinal sensory (dorsal root) ganglion 

Ventral ramus of spinal nerve 

Dorsal ramus of spinal nerve 

Dura mater 

Arachnoid mater 


Pia mater overlying spinal cord 

Filaments of dorsal root 

Membranes removed: anterior view 

(greatly magnified) 

Gray matter 

White matter 

Filaments of dorsal root 

Dorsal root of spinal nerve 

Filaments of ventral root 

Spinal sensory (dorsal 

root) ganglion 

Dorsal ramus of 

spinal nerve 

Ventral ramus of 

spinal nerve 

Ventral root of spinal nerve 

Spinal nerve 

Gray and white rami 

communicantes 

© 

FIGURE 2.13 

SPINAL MEMBRANES AND NERVE ROOTS • 

The spinal cord gives rise to 31 pairs of spinal nerves that distribute 

segmentally to the body. Motor fibers of these spinal nerves innervate 

skeletal muscle, and sensory fibers convey information back 

to the central nervous system from the skin, skeletal muscles, and 

joints. 

The spinal cord is ensheathed in three meningeal coverings: the 

outer, tough dura mater; the arachnoid mater; and the pia mater, 

which intimately ensheaths the cord itself. CSF bathes the cord and 

is found in the subarachnoid space. 

64

Peripheral Nervous System 


Posterior horn 

Dorsal root ganglion 

Sensory neuron cell body 

Dorsal root 

Anterior horn 

Motor neuron cell body 

Ventral root 

Peripheral nerve 

Axon 

Myelin sheath 

Motor neuron 

Sensory neuron 

Neuromuscular 

junction 

Skin 

Muscle 

with 

© 

FIGURE 2.14 

PERIPHERAL NERVOUS SYSTEM • 

The peripheral nervous system (PNS) consists of all of the neural 

elements outside of the CNS (brain and spinal cord) and provides 

the connections between the CNS and all other body organ systems. 

The PNS consists of somatic and autonomic components. The 

somatic component innervates skeletal muscle and skin and is 

shown here (see Figure 2.15 for the autonomic nervous system). 

The somatic component of the peripheral nerves contains both 

motor and sensory axons. Cell bodies of the motor neurons are 

found in the anterior horn gray matter, whereas the cell bodies of 

sensory neurons are located in the dorsal root ganglia. 

65


Autonomic Nervous System: Schema 






Sweat 

gland 

Peripheral 

blood vessel 

C1 

Arrector (smooth) 

muscle of hair follicle 

Note: Above three 

structures are shown at 

only one level but 

occur at all levels 

C2 

C3 

C4 

C5 

C6 

C7 

C8 

T1 

T2 

T3 

T4 

T5 

T9 

T10 

T7 

T8 

T11 

T12 

T6 

L1 

L2 

L3 

L4 

L5 

Note: Blue-shaded S1 

areas indicate zones of 

parasympathetic S2 

outflow from CNS S3 

S4 

S5 

Coccygeal 

Gray rami 

communicantes 

Gray and white rami communicantes 


Greater 

Lesser 

Least 

Lumbar 

splanchnic 

nerves 

⎧ 

⎨ 

⎩ 

Splanchnic 

nerves 

Pelvic 

splanchnic 

nerves 

Intracranial vessels 


Eye 


Lacrimal glands 

Otic ganglion 

Parotid glands 


Sublingual and 

submandibular glands 

Peripheral cranial 

and facial vessels 

Larynx 

Trachea 

Bronchi 

Lungs 

Heart 

Stomach 

Liver 

Gallbladder 

Bile ducts 

Pancreas 

Suprarenal glands 

Kidneys 

Intestines 

Descending colon 

Sigmoid colon 

Rectum 

Prostate 

External genitalia 


Pulmonary plexus 


Celiac ganglion 



ganglion 


ganglion 

Superior hypogastric 

plexus 

Inferior 

hypogastric 

plexus 

Sympathetic 

fibers 

Presynaptic 

Postsynaptic 


fibers 

Presynaptic 

Postsynaptic 

Antidromic 

conduction 

© 

FIGURE 2.15 

AUTONOMIC NERVOUS SYSTEM: SCHEMA • 

The autonomic nervous system is composed of two divisions: the 

parasympathetic division derived from four of the cranial nerves 

(CN III, VII, IX, and X) and the S2-S4 sacral spinal cord levels, and the 

sympathetic division associated with the thoracic and upper lumbar 

spinal cord levels (T1-L2). The autonomic nervous system is a twoneuron 

chain, with the preganglionic neuron arising from the central 

nervous system and synapsing on a postganglionic neuron located in 

66 

a peripheral autonomic ganglion. Postganglionic axons of the autonomic 

nervous system innervate smooth muscle, cardiac muscle, and 

glands. Basically, the sympathetic division mobilizes our body (“fight 

or flight”) while the parasympathetic division regulates digestive and 

homeostatic functions. Normally, both divisions work in concert to 

regulate visceral activity (respiration, cardiovascular function, digestion, 

and associated glandular activity).

Autonomic Nervous System: Cholinergic and Adrenergic Synapses 


Medulla 

oblongata 

Glossopharyngeal 

nerve (IX) 

Internal carotid nerve 


Parotid 

gland 

Larynx 

Trachea 

Bronchi 

Lungs 

Heart 

Cervical 

sympathetic 

ganglia 

Striated muscle 

Sweat glands 

Thoracic 

part of 

spinal cord 

Gray ramus 

communicans 

White ramus 

communicans 

Celiac 

ganglion 

Hair follicles 

Peripheral arteries 

Upper 

lumbar 

part of 

spinal cord 

(L1-2 [3]) 

Superior 

mesenteric 

ganglion 

Suprarenal 

gland 

Visceral 

arteries 

Gastrointestinal 

tract 

Inferior 

mesenteric ganglion 

Sacral 

part of 

spinal cord 


C Cholinergic synapses 

A Adrenergic synapses 


Urethra 

Prostate 

Sympathetic 

fibers 

Presynaptic 

Postsynaptic 


fibers 

Presynaptic 

Postsynaptic 

Somatic fibers 

Antidromic conduction 

© 

FIGURE 2.16 

CHOLINERGIC AND ADRENERGIC SYNAPSES: SCHEMA • 

The autonomic nervous system (ANS) is a two-neuron chain, with 

the preganglionic neuron arising from the central nervous system 

and synapsing on a postganglionic neuron located in a peripheral 

autonomic ganglion. Acetylcholine is the neurotransmitter in both 

the sympathetic and parasympathetic ganglia. The parasympathetic 

division of the ANS releases acetylcholine at its postganglionic 

synapses and is characterized as having cholinergic (C) effects, 

whereas the sympathetic division releases predominantly noradrenaline 

(norepinephrine) at its postganglionic synapses, causing 

adrenergic (A) effects (except on sweat glands, where acetylcholine 

is released). Although acetylcholine and noradrenaline are the 

chief transmitter substances, other neuroactive peptides often are 

colocalized with them and include such substances as gammaaminobutyric 

acid (GABA), substance P, enkephalins, histamine, 

glutamic acid, neuropeptide Y, and others. 

67


Hypothalamus 

Lateral 

ventricle 

Septum 

pellucidum 

Fornix 


Medial 

forebrain 

bundle 

Lateral 

preoptic 

nucleus 

Anterior 

commissure 

Medial 

preoptic 

nucleus 

From 

Thalamus 

hippocampal 

formation 

Interthalamic 

Lateral 

adhesion 

hypothalamic area 

Paraventricular nucleus 

Anterior hypothalamic area 

Dorsal hypothalamic area 

Dorsomedial nucleus 

Mamillothalamic tract 

Posterior area 

Periventricular 

nucleus 

Nucleus 

intercalatus 

Olfactory 

tract 

Optic (II) 

nerve 

Optic chiasm 

Anterior 

lobe of 

pituitary 

Fornix 

Ventromedial 

nucleus 

Mamillary 

complex 

Tuberohypophyseal tract 

Red nucleus 

Oculomotor (III) nerve 

Supraoptic nucleus 

Supraopticohypophyseal 

tract 

Posterior lobe of pituitary 

Cerebral 

peduncle 

Dorsal 

longitudinal 

fasciculus 

Descending 

hypothalamic 

connections 

Pons 

Reticular 

formation 

© 

CHART 2.3 

MAJOR FUNCTIONS OF THE HYPOTHALAMUS 

Hypothalamic Area 

Preoptic and anterior 

Posterior 

Lateral 

Ventromedial 

Supraoptic (subfornical organ and organum vasculosum) 

Paraventricular 

Periventricular 

*Stimulation of the center causes the responses listed. 

Major Functions* 

Heat loss center: cutaneous vasodilation and sweating 

Heat conservation center: cutaneous vasoconstriction and shivering 

Feeding center: eating behavior 

Satiety center: inhibits eating behavior 

ADH and oxytocin secretion (sensation of thirst) 

ADH and oxytocin secretion 

Releasing hormones for the anterior pituitary 

FIGURE 2.17 

SCHEMATIC RECONSTRUCTION OF THE HYPOTHALAMUS • 

The hypothalamus, part of the diencephalon, controls a number of 

important homeostatic systems within the body, including temperature 

regulation, food intake, water intake, many of the endocrine 

systems (see Chapter 8), motivation, and emotional behavior. It 

receives inputs from the reticular formation (sleep/wake cycle 

information), the thalamus (pain), the limbic system (emotion, fear, 

anger, smell), the medulla oblongata (blood pressure and heart 

rate), and the optic system, and it integrates these inputs for regulation 

of the functions listed. 

68

Limbic System 






Thalamus 

Uncus 



Hippocampus 

Commissure of fornix 



Columns 

of fornix 


Commissure 

of fornix 


Mamillary 

bodies 

Amygdaloid bodies 

Hippocampus 

with fimbria © 

FIGURE 2.18 

HIPPOCAMPUS AND FORNIX • 

The limbic system includes the hypothalamus and a collection of 

interconnected structures in the telencephalon (cingulate, parahippocampal, 

and subcallosal gyri), as well as the amygdala and hippocampal 

formation. The limbic system functions in linking emotion 

and motivation (amygdala), learning and memory (hippocampal 

formation), and sexual behavior (hypothalamus). 

69


The Cerebral Cortex 

Premotor; orientation; 

eye and head 

movements 

Motor 

Ms I 

Ms II 

Sm I 

Sm II 

Sensory 

Sensory 

analysis 

Prefrontal; 

inhibitory control 

of behavior; 

higher 

intelligence 

Visual III 

Visual II 

Visual I 

Motor control 

of speech 

Language; 

reading; speech 

Auditory I 

Auditory II 

Premotor 

Motor 

Ms I 

Ms II 

Sm I 

Sm III 

? 

Sensory 

Prefrontal; 

inhibitory control 

of behavior; 

higher 

intelligence 

Visual III 

Visual II 

Visual I 


(emotional behavior) 

and cingulum 


Hippocampal commissure 

© 

Olfactory 


FIGURE 2.19 

CEREBRAL CORTEX: LOCALIZATION OF FUNCTION AND ASSOCIATION PATHWAYS • 

The cerebral cortex is organized into functional regions. In addition 

to specific areas devoted to sensory and motor functions, there 

are areas that integrate information from multiple sources. The 

cerebral cortex participates in advanced intellectual functions, 

including aspects of memory storage and recall, language, higher 

cognitive functions, conscious perception, sensory integration, and 

planning/execution of complex motor activity. General cortical 

areas associated with these functions are illustrated. 

70

Descending Motor Pathways 


Motor 

cortex 

Internal 

capsule 

Hip 

Knee 

Ankle 

Toes 

Trunk 

Shoulder 

Elbow 

Wrist 

Fingers 

Thumb 

Neck 

Brow 

Eyelid 

Nares 

Lips 

Tongue 

Larynx 

Lateral aspect of 

cerebral cortex to show 

topographic projection 

of motor centers on 

precentral gyrus 

Midbrain 

Pons 

Medulla 

Basis 

pedunculi 

Basis 

pontis 

Pyramids 

Motor system 

Fibers originate in motor cortex and 

descend via posterior limb of internal 

capsule to basis pedunculi of midbrain 

Longitudinal bundles branch upon 

entering basis pontis and rejoin to 

enter pyramids of medulla 

At lower medulla, bulk of fibers cross 

median plane to form lateral 

corticospinal tract; some fibers 

continue downward in ipsilateral 

lateral corticospinal tract; others 

descending ipsilateral anterior 

corticospinal tract 

Medulla 

Above midthoracic 

level 

Decussation 

of pyramids 

Synapse occurs at spinal level: Lateral 

corticospinal fibers synapse on 

ipsilateral anterior horn cells; anterior 

corticospinal fibers synapse on 

contralateral anterior horn cells 

Motor 

endplate 

Spinal 

cord 

Below midthoracic 

level 

Anterior corticospinal tract 

Lateral corticospinal tract 

Motor 

endplate 

© 

FIGURE 2.20 

CORTICOSPINAL TRACTS • 

The corticospinal, or pyramidal, tract is the major motor tract that 

controls voluntary movement of the skeletal muscles, especially 

skilled movements of distal muscles of the limbs. All structures 

from the cerebral cortex to the anterior horn cells in the spinal 

cord constitute the upper portion of the system (upper motor neuron). 

The anterior horn cells and their associated axons constitute 

the lower portion of the system (lower motor neuron). 

71


Cerebellum: Afferent Pathways 



Cortical input 

Nucleus 

reticularis 

tegmenti 

pontis 

Pontine nuclei 

(contralateral) 

Spinal input 

Inferior olive 

Leg 

Arm Face 

To contralateral cerebellar cortex 

Primary fissure 

Upper part 

of medulla 

oblongata 

Spinal input 

Vestibular nerve 

and ganglion 

Lower part 

of medulla 

oblongata 

Cortical input 

Lateral reticular 

nucleus 

Spinal input 

Cervical part 


Motor interneuron 

Rostral 

spinocerebellar 

tract 

Spinal border cells 

Motor interneuron 

Lumbar part 


Clarke’s column 

Ventral spinocerebellar 

tract 

Vestibular 

nuclei 

To nodule and flocculus 


Reticulocerebellar 

tract 

Cuneocerebellar 

tract 

Gracile nucleus 

Main cuneate 

nucleus (relay 

for cutaneous 

information) 

External cuneate nucleus 

(relay for proprioceptive 

information) 

From skin (touch 

and pressure) 

From muscle (spindles 

and Golgi tendon organs) 

From skin and 

deep tissues 

(pain and Golgi 

tendon organs) 

From skin (touch 

and pressure) 

and from muscle 

(spindles and 

Golgi tendon 

organs) 

Dorsal spinocerebellar tract 

Leg zone 

Arm zone 

Face zone 

2nd spinal 

projection 

area (gracile 

lobule) 

Archicerebellum 

(vestibulocerebellum) 

Paleocerebellum 

(spinocerebellum) 

Functional Subdivisions of Cerebellum 

Hemisphere Vermis 

Intermediate 

Lateral 

part part 

Lingula 

Flocculus 

Nodule 

Neocerebellum 

(pontocerebellum) 

Uvula 

Pyramid 

Vermis 

Middle vermis 

Hemisphere 

Anterior lobe 

Primary 

fissure 

Middle 

(posterior) 

lobe 

Posterolateral 

fissure 

Flocculonodular 

lobe 

Schema of 

theoretical 

“unfolding” 

of cerebellar 

surface in 

derivation of 

above diagram 

FIGURE 2.21 

CEREBELLAR AFFERENT PATHWAYS • 

© 

72 

The cerebellum plays an important role in coordinating movement. It 

receives sensory information and then influences descending motor 

pathways to produce fine, smooth, and coordinated motion. The 

cerebellum is divided into three general areas: archicerebellum (also 

called vestibulocerebellum) paleocerebellum (also called spinocerebellum) 

and the neocerebellum (also called the cerebrocerebellum). 

The archicerebellum is primarily involved in controlling posture and 

balance, as well as the movement of the head and eyes. It receives 

afferent signals from the vestibular apparatus and then sends efferent 

fibers to the appropriate descending motor pathways. The paleocerebellum 

primarily controls movement of the proximal portions of the 

limbs. It receives sensory information on limb position and muscle 

tone and then modifies and coordinates these movements through 

efferent pathways to the appropriate descending motor pathways. The 

neocerebellum is the largest portion of the cerebellum, and it coordinates 

the movement of the distal portions of the limbs. It receives 

input from the cerebral cortex and thus helps in the planning of 

motor activity (e.g., seeing a pencil and then planning and executing 

the movement of the arm and hand to pick it up).

Cerebellum: Efferent Pathways 


Excitatory 

endings 

Inhibitory 

endings of 

Purkinje 

cells 

Motor and 

premotor 

cerebral 

cortex 

Ventral anterior and 

ventral lateral nuclei 

of thalamus 

Mesencephalic reticular formation 

Dentate nucleus 

Cerebellar 

cortex 

Globose nuclei 

Emboliform nucleus 

Red nucleus 

Fastigial nucleus 



Decussation of superior 

cerebellar peduncles 

Descending fibers from 

superior cerebellar 

peduncles 

Hook bundle of Russell 

Section 

A–B 

viewed 

from 

below 

Vestibular 

nuclei 

Section 

B–C 

viewed 

from 

above 


peduncle 

Inferior olive 

Lateral reticular nucleus 


Pontomedullary reticular formation 

A 

Planes of 

section: 

red arrows 

indicate 

C 

direction 

of view 

B 

© 

FIGURE 2.22 

CEREBELLAR EFFERENT PATHWAYS • 

The cerebellum plays an important role in coordinating movement. 

It influences descending motor pathways to produce fine, smooth, 

and coordinated motion. The archicerebellum is primarily involved 

in controlling posture and balance and movement of the head and 

eyes. It sends efferent fibers to the appropriate descending motor 

pathways. The paleocerebellum primarily controls movement of 

the proximal portions of the limbs. It modifies and coordinates 

these movements through efferent pathways to the appropriate 

descending motor pathways. The neocerebellum coordinates the 

movement of the distal portions of the limbs. It helps in the planning 

of motor activity (e.g., seeing a pencil and then planning and 

executing the movement of the arm and hand to pick it up). 

73


Cutaneous Sensory Receptors 

Basal 

epithelial 

cells 

Hair follicle 


Hair shaft 

Melanocyte 

Arrector muscle of hair 

Sebaceous gland 

Cuticle 

Internal sheath 

External sheath 

Glassy 

membrane 

Connective 

tissue layer 

Hair cuticle 

Sweat gland 

Hair matrix 

Papilla of hair follicle 

Pacinian 

corpuscle 

Artery 

Detail of Merkel’s disc 

Meissner’s corpuscle 

Pore of sweat gland 

Vein 

Sensory nerves 

Elastic fibers 

Skin ligaments 

(retinacula cutis) 

Motor 

(autonomic) 

nerve 

Desmosomes 

Cutaneous 

nerve 

Stratum corneum 

Stratum 

lucidum 

Stratum 

spinosum 

Dermal 

papilla 

(of papillary 

layer) 

Reticular 

layer 

Stratum 

granulosum 

Subcutaneous 

artery and vein 

Cross section 

Stratum 

basale 

Epidermis Dermis Subcutaneous tissue 


Axon terminal 

Mitochondrion 

Schwann cell 

Cytoplasmic 

protrusion 

Merkel 

cell 

Mitochondria 

Lobulated 

nucleus 

Expanded 

axon terminal 

Granulated 

vesicles 

Axon 

© 

Schwann 

cell 

Schwann cells 

Detail of free nerve ending 

FIGURE 2.23 

SKIN AND CUTANEOUS RECEPTORS • 

Cutaneous receptors respond to touch (mechanoreceptors), pain 

(nociceptors), and temperature (thermoreceptors). Several different 

types of receptors are present in skin. Meissner’s corpuscles have 

small receptive fields and respond best to stimuli that are applied 

at low frequency (i.e., flutter). The pacinian corpuscles are located 

in the subcutaneous tissue and have large receptive fields. They 

respond best to high-frequency stimulation (i.e., vibration). 

Merkel’s discs have small receptive fields and respond to touch and 

pressure (i.e., indenting the skin). Ruffini’s corpuscles have large 

receptive fields, and they also respond to touch and pressure. Free 

nerve endings respond to pain and temperature. 

74

Cutaneous Receptors: Pacinian Corpuscle 


Pacinian Corpuscle 

as Pressure Transducer 

To amplifier 

Pressure 

Generator potential 

Action potential 

A. Sharp “on and off” changes in pressure at start and end 

1st node 

Pressure Na + of pulse applied to lamellated capsule are transmitted to 

Myelin sheath central axon and provoke generator potentials, which in 

Lamellated capsule 

turn may trigger action potentials; there is no response to a 

slow change in pressure gradient. Pressure at central core 

Central core 

Unmyelinated axon terminal 

and, accordingly, generator potentials are rapidly dissipated 

by viscoelastic properties of capsule (Action potentials may 

be blocked by pressure at a node or by drugs) 

Pressure 

To amplifier 

Generator potential 

B. In absence of capsule, axon responds to slow as well 

as to rapid changes in pressure. Generator potential 

dissipates slowly, and there is no “off” response 

Action potential 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pressure applied to axon terminal directly or 

via capsule causes increased permeability of 

membrane to Na + , thus setting up ionic 

generator current through 1st node 

 

 

 

 

 

 

 

 

If resultant depolarization at 1st node is great 

enough to reach threshold, an action potential 

appears which is propagated along nerve fiber 

© 

FIGURE 2.24 

PACINIAN CORPUSCLE • 

Pacinian corpuscles are mechanoreceptors that transduce mechanical 

forces (displacement, pressure, vibration) into action potentials 

that are conveyed centrally by afferent nerve fibers. As the viscoelastic 

lamellae are displaced, the unmyelinated axon terminal 

membrane’s ionic permeability is increased until it is capable of 

producing a “generator potential.” As demonstrated in the figure, 

pacinian corpuscles respond to the beginning and end of a 

mechanical force while the concentric lamellae dissipate slow 

changes in pressure. In the absence of the capsule, the generator 

potential decays slowly and yields only a single action potential. 

75


Proprioception and Reflex Pathways: I 

Spinal Effector Mechanisms 

Dorsal horn 

interneuron 

From motor neuron 


Dorsal horn interneuron 

From 

cutaneous 

receptor 

From 

muscle 

spindle 

Flexor reflex interneuron 

Dorsal horn interneuron 

Dorsal root 

ganglion 

Ventral root 

To motor neuron 

motor axon 

To motor neuron 

Schematic representation of motor neurons 

In cervical 

enlargement of 

spinal cord 

Flex ors 

Extensors 

In lumbar 

enlargement 


Fle 

xors 

Exte nsors 

© 

FIGURE 2.25 

PROPRIOCEPTION: SPINAL EFFECTOR MECHANISM • 

Position sense or proprioception involves input from cutaneous 

mechanoreceptors, Golgi tendon organs, and muscle spindles 

(middle figure of upper panel). Both monosynaptic reflex pathways 

(middle figure of upper panel) and polysynaptic pathways involving 

several spinal cord segments (top and bottom figures of upper 

panel) initiate muscle contraction reflexes. The lower panel shows 

the somatotopic distribution of the motor neuron cell bodies in the 

ventral horn of the spinal cord that innervate limb muscles (flexor 

and extensor muscles of upper and lower limbs). 

76

Proprioception and Reflex Pathways: II 


Alpha motor neurons to extrafusal 

striated muscle end plates 

Gamma motor neurons to intrafusal 

striated muscle end plates 

Ia (A) fibers from annulospiral 

endings (proprioception) 

II (A) fibers from flower spray 

endings (proprioception); 

from paciniform corpuscles (pressure) 

and pacinian corpuscles (pressure) 

III (A) fibers from free nerve endings 

and from some specialized endings 

(pain and some pressure) 

IV (unmyelinated) fibers from free 

nerve endings (pain) 

Ib (A) fibers from Golgi tendon 

organs (proprioception) 

Alpha motor neuron to extrafusal 

muscle fiber end plates 

A fibers from 

Golgi-type 

endings 

A fibers from 

paciniform corpuscles 

and Ruffini terminals 

A and C fibers 

from free nerve 

endings 

Gamma motor neuron to intrafusal 

muscle fiber and plates 

II (A) fiber from flower spray endings 

Ia (A) fiber from annulospiral endings 

Detail of 

muscle spindle 

Sheath 

Lymph space 

Nuclear bag fiber 

Nuclear chain fiber 

Extrafusal 

muscle fiber 

Intrafusal 

muscle fibers 

© 



FIGURE 2.26 

MUSCLE AND JOINT RECEPTORS • 

Muscle spindles and Golgi tendon organs send afferent signals to 

the brain to convey the position of limbs and help coordinate muscle 

movement. Muscle spindles convey information on muscle tension 

and contraction (dynamic forces) and muscle length (static 

forces). The nuclear bag fibers respond to both dynamic and static 

forces, whereas the nuclear chain fibers respond to static forces. 

Intrafusal fibers maintain appropriate tension on the nuclear bag 

and nuclear chain fibers. If the muscle tension is too great (e.g., 

overstretching of muscle or too heavy a load), activation of the 

Golgi tendon organ causes a reflex relaxation of the muscle. 

77


Proprioception and Reflex Pathways: III 

Ib fibers 

Ia fibers 

Extrafusal muscle fiber 

Intrafusal muscle fiber 

Alpha motor neurons 

Gamma motor neurons 

Golgi 

tendon 

organ 

A. Passive stretch. Both intrafusal and extrafusal muscle fibers stretched; 

spindles activated. Reflex via Ia fibers and alpha motor neurons causes 

secondary contraction (basis of stretch reflexes, such as knee jerk). 

Stretch is too weak to activate Golgi tendon organs 

Ib fibers 

Ia fibers 

Alpha activation 

from brain 



Inhibitory interneuron 


Gamma motor neurons 

Golgi 

tendon 

organ 

B. Active contraction. Central excitation of alpha motor neurons 

only causes contraction of extrafusal muscle fibers with consequent 

relaxation of intrafusal fibers; spindles not activated. Tension is low; 

does not adjust to increased resistance. Tendon organ activated, 

causing relaxation 

Alpha and 

Ib fibers 

gamma 

activation 

from brain 

Ia fibers 




Gamma motor neurons 

Golgi 

tendon 

organ 

C. Active contraction with gamma coactivation. Intrafusal as well as 

extrafusal fibers contract; spindles activated, reinforcing contraction 

stimulus via Ia fibers in accord with resistance. Tendon organ 

activated, causing relaxation if load is too great 

© 

FIGURE 2.27 

PROPRIOCEPTIVE REFLEX CONTROL OF MUSCLE TENSION • 

Interaction of the muscle spindle and Golgi tendon organ during passive stretch of a muscle (panel A) and during a contraction (panels B 

and C). 

78

Proprioception and Reflex Pathways: IV 


A. Afferent inhibition 

From extensor spindle 

receptor (Ia, II fibers) 

From flexor spindle 

(Ia, II fibers) 

Axoaxonic presynaptic 

inhibitory synapse 

To extensors 

B. Stretch reflex 

(reciprocal inhibition) 

From extensor spindle 

receptor (Ia, II fibers) 

Axosomatic or 

axodendritic 

inhibitory 

synapse 

Excitatory 

synapse 

To extensors 

To flexors 

C. Recurrent inhibition 

D. Tendon organ reflex 

From extensor tendon 

organ (Ib fibers) 

Inhibitory synapse 

Renshaw cells 

Collaterals 

To synergistic 

muscles 

Excitatory synapse 

To extensors 

To flexors 

E. Flexor withdrawal reflex 

Nociceptive fibers 

Ipsilateral 

flexion 

Contralateral 

extension 



To extensors 

To flexors 



To extensors 

To flexors 

© 

FIGURE 2.28 

SPINAL REFLEX PATHWAYS • 

Summary of the spinal reflex pathways. 

79


Sensory Pathways: I 

Cerebral cortex: 

postcentral gyrus 

Posterior limb of 

internal capsule 

Ventral posterolateral 

(VPL) nucleus of 

thalamus 

Mesencephalon 

(cerebral peduncles) 

Medial lemniscus 

Spinothalamic tract 

Gracile nucleus 

Cuneate nucleus 

Lower part of 

medulla oblongata 

Reticular formation 

Cervical part 


Lateral 

spinothalamic tract: 

pain, temperature 

Ventral (anterior) 

spinothalamic tract: 

touch, pressure 

Fasciculus gracilis 

Fasciculus cuneatus 

Dorsal (posterior) spinal 

root ganglion 

Proprioception, 

position 

Touch, 

pressure, 

vibration 

Pain, 

temperature 

Lateral cervical nucleus 

Spinocervical tract 

Large 

myelinated 

fibers 

Small 

myelinated 

and unmyelinated 

fibers 

Lumbar part 


© 

FIGURE 2.29 

SOMESTHETIC SYSTEM OF THE BODY • 

Pain, temperature, and pressure sensations below the head ultimately 

are conveyed to the primary somatosensory cortex (postcentral 

gyrus) by the anterolateral system (spinothalamic and spinoreticular 

tracts). The fasciculus gracilis and cuneatus of the spinal 

lemniscal system convey proprioceptive, vibratory, and tactile sensations 

to the thalamus (ventral posterolateral nucleus), whereas 

the lateral cervical system mediates some touch, vibratory, and 

proprioceptive sensations (blue and purple lines show these dual 

pathways). Ultimately, these fibers ascend as parallel pathways to 

the thalamus, synapse, and ascend to the cortex. 

80

Sensory Pathways: II 


Cerebral cortex: 

postcentral gyrus 

Ventral posteromedial (VPM) 

nucleus of thalamus 


Midbrain 

(cerebral 

peduncles) 

Ventral 

trigeminal 

lemniscus 

Pontine 

reticular 

formation 

Pons 

Dorsal trigeminal lemniscus 

Trigeminal mesencephalic nucleus 

Trigeminal motor nucleus 

Principal sensory trigeminal nucleus 

Touch, pressure 

Pain, temperature 

Proprioception 

Trigeminal (semilunar) ganglion 

Ophthalmic n. 

Maxillary n. 

Sensory root 

and 

Motor root of mandibular n. 

Medullary 

reticular 

formation 

Spinal 

trigeminal 

tract 

Spinal 

trigeminal 

nucleus 

Cervical 

part of 

spinal 

cord 

Facial (VII) n. 

Vagus (X) n. 

Dorsolateral fasciculus (of Lissauer) 

Substantia gelatinosa (Iamina II) 

© 

FIGURE 2.30 

SOMESTHETIC SYSTEM OF THE HEAD • 

Nerve cells bodies for touch, pressure, pain, and temperature in 

the head are in the trigeminal (semilunar) ganglion of the trigeminal 

(CN V) nerve (blue and red lines in figure). Neuronal cell bodies 

mediating proprioception reside in the mesencephalic nucleus 

of CN V (purple fibers). Most relay neurons project to the contralateral 

VPM nucleus of the thalamus and thence to the postcentral 

gyrus of the cerebral cortex, where they are somatotopically 

represented. 

81


Sensory Pathways: III 

C2 

C3 

C4 

C5 

T1 

T2 

T3 

T4 

T5 

T6 

T7 

T8 

T9 

T10 

T11 

T12 

L1 

S2, 3 

L2 

L3 

L4 

T1 

C8 

C6 

Schematic demarcation of 

dermatomes shown as distinct 

segments. There is actually 

considerable overlap between 

any two adjacent dermatomes 

C5 

C7 

C6 

C7 

C6 

C7 

C8 

S3 

S4 

S5 

C7 C8 

C8 

L5 

L1 

L2 

L3 

C2 

C3 

C4 

C5 

C6 

T1 

T2 

T3 

T4 

T5 

T6 

T7 

T8 

T9 

T10 

T11 

T12 

L1 

L2 

L3 

L4 

L5 

S1 

S2 

S1 

S2 

L5 

S1 S2 

L5 

S1 

L4 

L4 

S1 

L5 

L4 

Levels of principal dermatomes 

C5 Clavicles 

C5, 6, 7 Lateral parts of upper limbs 

C8, T1 Medial sides of upper limbs 

C6 Thumb 

C6, 7, 8 Hand 

C8 Ring and little fingers 

T4 Level of nipples 

T10 Level of umbilicus 

T12 Inguinal or groin regions 

L1, 2, 3, 4 Anterior and inner surfaces of lower limbs 

L4, 5, S1 Foot 

L4 Medial side of great toe 

S1, 2, L5 Posterior and outer surfaces of lower limbs 

S1 Lateral margin of foot and little toe 

S2, 3, 4 Perineum 

© 

FIGURE 2.31 

DERMATOMES • 

Sensory information below the head is localized to specific areas 

of the body, which reflect the distribution of peripheral sensory 

fibers that convey sensations to the spinal cord through the dorsal 

roots (sensory nerve cell bodies reside in the corresponding dorsal 

root ganglion). The area of skin subserved by afferent fibers of one 

dorsal root is called a dermatome. This figure shows the dermatome 

segments and lists key dermatome levels used by clinicians. 

Variability and overlap occur, so all dermatome segments 

are only approximations. 

82

Visual System: Receptors 


A. Eyeball 

Suspensory 

ligament 

Iris Lens 

Cornea 

Ciliary 

body 

B. Section 

through retina 

Inner limiting 

membrane 

Axons at surface 

of retina passing 

via optic nerve, 

chiasm, and tract 

to lateral 

geniculate body 

Ora 

serrata 

Anterior 

chamber 

Posterior 

chamber 

containing 

aqueous humor 

Vitreous humor 

Retina 

Choroid 

Sclera 

Fovea 

Optic nerve 

Ganglion cell 

Müller cell 

(supporting glial 

cell) 

Amacrine cell 

Bipolar cell 

Horizontal cell 

Rod 

Cone 

Pigment cells 

of choroid 

Synaptic 

ending 

depolarized 

C. Rod in dark D. Rod in light 

Synaptic 

ending 

fully 

polarized 

Synaptic bar 

Photons 

of light 

Nucleus 

Rhodopsin 

Lumirhodopsin 

Current 

flow 

Na + 

permeability 

increased 

Retinene 

+ 

Opsin 

Vitamin A 

Metabolic 

energy 

Circulation 

Metarhodopsin 

Retinene 

+ 

Opsin 

Vitamin A 

Centriole 

(basal body) 

Na + 

permeability 

decreased 

© 

FIGURE 2.32 

VISUAL RECEPTORS • 

The rods and cones of the retina transduce light into electrical signals. 

As illustrated for the rod, light is absorbed by rhodopsin, and 

through the second messenger cGMP (not shown), Na channels 

in the membrane close and the cell hyperpolarizes. Thus, in the 

dark the cell is depolarized, but it is hyperpolarized in the light. 

This electrical response to light is distinct from other receptor 

responses, in which the response to a stimulus results in a depolarization 

of the receptor cell membrane. 

83


Visual System: Visual Pathway 

G 

A 

B 

H 

G 

B 

A 

H 

Overlapping 

visual fields 

Central 

darker 

circle 

represents 

macular 

zone 

Lightest 

shades 

represent 

monocular 

fields 

Each 

quadrant 

a different 

color 

R R C 

C 

Projection on 

left retina 

Projection on 

right retina 

P 

P 

Choroid Choroid 

Periphery Macula 

Structure of retina (schematic): 

A Amacrine cells 

B Bipolar cells 

C Cones 

G Ganglion cells 

H Horizontal cells 

P Pigment cells 

R Rods 




Optic 

(II) nerves 

Optic chiasm 

Optic tracts 

Lateral 

geniculate 

bodies 




Calcarine 

fissure 

Projection 

on left 


Projection 

on right 


© 

FIGURE 2.33 

RETINOGENICULOSTRIATE VISUAL PATHWAY • 

The retina has two types of photoreceptors: cones that mediate 

color vision and rods that mediate light perception but with low 

acuity. The greatest acuity is found in the region of the macula of 

the retina, where only cones are found (upper left panel). Visual 

signals are conveyed by the ganglion cells whose axons course in 

the optic nerves. Visual signals from the nasal retina cross in the 

optic chiasm while information from the temporal retina remains in 

the ipsilateral optic tract. Fibers synapse in the lateral geniculate 

nucleus (visual field is topographically represented here and 

inverted), and signals are conveyed to the visual cortex on the 

medial surface of the occipital lobe. 

84

Auditory System: Cochlea 


A. Membranous 

labyrinth within 

bony labyrinth 

(path of sound 

waves) 

Cochlear nerve 

Utricle 

Saccule 

Semicircular 

canals 

Scala vestibuli 

Cochlear duct 

(scala media) 

Scala tympani 

B. Section 

through turn 

of cochlea 

Efferent 

nerve fibers 

Afferent 

nerve fibers 

Spiral ganglion 

Round window 

Scala vestibuli 

(perilymph); 

weakly 

positive +80 mV 

Scala tympani 

(perilymph); 0 mV 

Oval window and stapes 

Vestibular (Reissner’s) 

membrane 

Cochlear duct (scala media; 

endolymph) 

Tectorial membrane 

Spiral ligament 

Bone 

Outer hair cells; 60 mV 

Basilar membrane 

Inner hair cell; 60 mV 

C. Spiral organ 

of Corti 

Hair cells 

Inner Outer 

Tectorial membrane 

Stereocilia 

Rods 

and 

tunnel 

of Corti 

Basilar membrane 

Supporting cells 

Spiral lamina Afferent nerve fibers 


Efferent nerve fibers 

As basilar membrane moves up, hairs are deflected outward, causing 

depolarization of hair cells and increased firing of afferent nerve fibers 

© 

FIGURE 2.34 

COCHLEAR RECEPTORS • 

The cochlea transduces sound into electrical signals. This is 

accomplished by the hair cells, which depolarize in response to 

vibration of the basilar membrane. The basilar membrane moves in 

response to pressure changes imparted on the oval window of the 

cochlea in response to vibrations of the tympanic membrane. 

85


Auditory System: Pathways 

Acoustic area of 

temporal lobe cortex 


Brachium of 

inferior 

colliculus 

Inferior 

colliculus 

Midbrain 

Lateral 

lemnisci 

Medulla 

oblongata 

Nuclei of 

lateral 

lemnisci 

Correspondence 

between cochlea 

and acoustic area 

of cortex: 

Low tones 

Middle tones 

High tones 

Dorsal cochlear nucleus 


Ventral cochlear nucleus 

Cochlear division of 

vestibulocochlear nerve 

Dorsal 

acoustic stria 

Reticular formation 

Trapezoid body 

Intermediate acoustic stria 

Superior olivary complex 

Inner Outer 


Hair cells 

© 

FIGURE 2.35 

AUDITORY PATHWAYS • 

The cochlea transduces sound into electrical signals. Axons convey 

these signals to the dorsal and ventral cochlear nuclei, where it is 

tonotopically organized. Following a series of integrated relay 

pathways, the ascending pathway projects to the thalamus (medial 

geniculate bodies) and then the acoustic cortex in the transverse 

gyrus of the temporal lobe, where information is tonotopically represented 

(low, middle, and high tones). 

86

Vestibular System: Receptors 


Vestibular ganglion 

Vestibular 

and cochlear 

divisions of 

vestibulocochlear n. 

Maculae 

Saccule 

Utricle 

Cochlear duct 

(scala media) 

A. Membranous labyrinth 

Superior semicircular 

canal 

Cristae within 

ampullae 

Horizontal semicircular 

canal 

Posterior semicircular 

canal 

B. Section of crista 

Opposite wall 

of ampulla 

Gelatinous cupula 

Hair tufts 

Hair cells 

Nerve fibers 

Basement 

membrane 

C. Section of macula 

Otoconia 

Gelatinous otolithic 

membrane 

Hair tuft 

Hair cells 



Nerve fibers 

D. Structure and innervation 

of hair cells 

Hair cell (type I) 


Afferent nerve 

calyx 

Efferent nerve 

ending 

Basement 

membrane 

Kinocilium 

Stereocilia 

Cuticle 

Excitation 

Inhibition 

Basal body 

Cuticle 

Kinocilium 

Stereocilia 

Basal body 

Hair cell (type II) 

Supporting cell 

Efferent nerve 

endings 

Afferent nerve 

endings 

Myelin sheath 

Myelin sheath 

© 

FIGURE 2.36 

VESTIBULAR RECEPTORS • 

The vestibular apparatus detects movement of the head in the form 

of linear and angular acceleration. This information is important for 

the control of eye movements so that the retina can be provided 

with a stable visual image. It is also important for the control of 

posture. The utricle and saccule respond to linear acceleration, 

such as the pull of gravity. The three semicircular canals are 

aligned so that the angular movement of the head can be sensed in 

all planes. The sensory hair cells are located in the maculae of the 

utricle and saccule and in the cristae within each ampullae. 

87


Vestibular System: Vestibulospinal Tracts 

Excitatory 

endings 

Inhibitory 

endings 

Ascending fibers in medial 

longitudinal fasciculi 

Superior 

Medial 

Lateral 

Inferior 

Vestibular nuclei 

Upper 

limb 

Rostral 

Trunk 

Ventral 

Dorsal 

To 

cerebellum 

Caudal 

Lower 

limb 

Somatotopical 

pattern in lateral 

vestibular nucleus 

Motor neuron 

(controlling 

neck muscles) 

Vestibular 

ganglion 

and 

nerve 

Medial vestibulospinal 

fibers in medial 

longitudinal fasciculi 

Lateral 

vestibulospinal 

tract 

Fibers from cristae 

(rotational stimuli) 

Excitatory 

endings 

to back 

muscles 

? ? 

Excitatory 

interneuron 

Inhibitory 

interneuron 

Fibers from maculae 

(gravitational stimuli) 

Lower 

part of 

cervical 

spinal cord 

To axial 

muscles 

Lumbar part of 

spinal cord 

? 

Inhibitory 

ending 

To flexor muscles 

To extensor muscles 

Inhibitory ending 

? 

To axial muscles 

Excitatory ending 

Lateral vestibulospinal tract 

Inhibitory interneuron 


To flexor muscles 

To extensor muscles 

© 

FIGURE 2.37 

VESTIBULOSPINAL TRACTS • 

Sensory input from the vestibular apparatus is used to maintain stability 

of the head and to maintain balance and posture. Axons convey 

vestibular information to the vestibular nuclei in the pons, and 

then secondary axons distribute this information to five sites: spinal 

cord (muscle control), cerebellum (vermis), reticular formation 

(vomiting center), extraocular muscles, and cortex (conscious perception). 

This figure shows only the spinal cord pathways. 

88

Gustatory (Taste) System: Receptors 


A. Tongue 

Foliate 

papillae 

B. Section 

through 

vallate 

papilla 

Taste buds 

Duct of 

gustatory 

(Ebner’s) 

gland 

Fungiform 

papillae 

Vallate papillae 

Microvilli 

Taste pore 

Taste cells 

C. Taste bud 

Epithelium 


Nerve plexus 

Nerve fibers 

emerging from 

taste buds 

Desmosomes 

Epithelium 

Large nerve fiber 

Granules 


Small nerve fiber 

Fibroblast 

Schwann cell 

Microvilli 

Intercellular space Large nerve fiber 

Collagen 

D. Detail of taste pore E. Detail of base of receptor cells 

© 

FIGURE 2.38 

TASTE RECEPTORS • 

Taste buds on the tongue respond to various chemical stimuli. Taste 

cells, like neurons, normally have a net negative charge internally 

and are depolarized by stimuli, thus releasing transmitters that depolarize 

neurons connected to the taste cells. A single taste bud can 

respond to more than one stimulus. The four traditional taste qualities 

that are sensed are sweet, salty, sour, and bitter. 

89


Gustatory (Taste) System: Pathways 

Ventral posteromedial (VPM) 

nucleus of thalamus 

Sensory cortex (just below 

face area) 

Lateral hypothalamic area 

Amygdala 

Mesencephalic 

nucleus 

and 

Motor nucleus 

of trigeminal n. 

Pontine taste area 

Trigeminal (V) n. 

Maxillary n. 

Mandibular n. 

Pons 

Greater petrosal n. 



ganglion 

Facial (VII) n. 

and 

Nervus inermedius 

Rostral part of nucleus 

of solitary tract 

Glossopharyngeal (IX) n. 

Lower 

part of 

medulla 

oblongata 

Otic 

ganglion 

Chorda 

tympani 

Fungiform papillae 

Foliate papillae 

Valiate papillae 

Lingual n. 

Petrosal (inferior) 

ganglion of 

glossopharyngeal n. 

Epiglottis 

Larynx 

Nodose (inferior) 

ganglion of vagus n. 

Vagus (X) n. 

Superior laryngeal n. 

© 

FIGURE 2.39 

TASTE PATHWAYS • 

Depicted here are the afferent pathways leading from the taste receptors to the brainstem and, ultimately, to the sensory cortex in the 

postcentral gyrus. 

90

Olfactory System: Receptors 


Olfactory 

bulb 

A. Distribution 

of olfactory 

epithelium 

(blue area) 

Cribriform plate 

of ethmoid bone 

Lateral nasal wall 

Septum 

B. Schema of 

section through 

olfactory mucosa 

Cribriform plate 

Schwann cell 

Olfactory gland 

Unmyelinated 

olfactory axons 

Basement 

membrane 

Sustentacular 

cells 

Endoplasmic 

reticulum 

Nucleus 

Olfactory cells 

Dendrites 

Terminal bars 

(desmosomes) 

Olfactory rod 

(vesicle) 

Villi 

Cilia 

Mucus 

© 

FIGURE 2.40 

OLFACTORY RECEPTORS • 

The sensory cells that make up the olfactory epithelium respond to 

odorants by depolarizing. Like taste buds, an olfactory cell can 

respond to more than one odorant. There are six general odor 

qualities that can be sensed: floral, ethereal (e.g., pears), musky, 

camphor (e.g., eucalyptus), putrid, and pungent (e.g., vinegar, peppermint). 

91


Olfactory System: Pathway 



Granule cell (excited by 

and inhibiting to mitral 

and tufted cells) 

Mitral cell 

Recurrent process 

Tufted cell 

Periglomerular 

cell 

Glomerulus 

Olfactory 

nerve fibers 

Fibers from contralateral olfactory bulb 

Fibers to contralateral olfactory bulb 


Medial olfactory stria 

Olfactory trigone and 

olfactory tubercle 

Anterior perforated 

substance 

Lateral olfactory 

stria 

Lateral olfactory 

tract nucleus 

Piriform lobe 

Uncus 

Amygdala 

(in phantom) 

Entorhinal area 

Olfactory epithelium 

Olfactory nerves 



Anterior olfactory nucleus 

Cribriform plate of ethmoid bone 

© 

FIGURE 2.41 

OLFACTORY PATHWAY • 

Olfactory stimuli are detected by the nerve fibers of the olfactory 

epithelium and conveyed to the olfactory bulb (detailed local circuitry 

shown in upper left panel). Integrated signals pass along the 

olfactory tract and centrally diverge to pass to the anterior commissure 

(some efferent projections course to the contralateral olfactory 

bulb, blue lines) or terminate in the ipsilateral olfactory trigone 

(olfactory tubercle). Axons then project to the primary olfactory 

cortex (piriform cortex), entorhinal cortex, and amygdala. 

92

Installing Adobe Acrobat Reader 

The images and text included in this atlas are contained in a Portable Document Format (pdf) 

file and can be viewed with Adobe Acrobat Reader. A copy of Acrobat Reader 6.0 is included 

on this CD. You will need to install or upgrade to Acrobat Reader 5.0 or later in order to 

have full functionality. 

Please follow these instructions: 

Windows 

1. Choose Run from the Start menu and then click Browse. 

2. Navigate to the Acrobat Reader folder on the NeuroAtlas CD. 

3. Double-click the setup.exe file to open the Acrobat Reader Installer. 

4. Follow the onscreen instructions. 

Macintosh OS X 

1. Double-click the Acrobat Reader folder on the NeuroAtlas CD. 

2. Copy the Adobe Reader 6.0 folder to the Applications folder. 

3. To complete the installation, double-click the Adobe Reader 6.0 file in your Applications 

folder. 

Note: If you are using Macintosh 9.2 or earlier, you should go to the following URL to download the Adobe 

Acrobat Reader. http://www.adobe.com/products/acrobat/readstep2.html 

Running the Atlas of Neuroanatomy and Neurophysiology 

Windows 

1. Insert the CD into the CD-ROM drive. 

2. If Acrobat Reader 5.0 or greater is not already installed on your computer, follow the installation 

instructions above. 

3. Choose Run from the Start menu and type x:\ (where x is the letter of your CD-ROM drive). 

4. Under Files of Type, click All Files. 

5. Double-click the Neuro Atlas.pdf file to open the program. 

6. For best viewing results in Acrobat Reader 5.0, use the Edit menu to access the Preferences. 

Select General and open the Display preferences to activate the Smooth Line Art option. 

Macintosh 

1. Insert the CD into the CD-ROM drive. 

2. If Acrobat Reader 5.0 or greater is not already installed on your computer, follow the installation 

instructions above. 

3. Double-click the Neuro Atlas.pdf file to open the program. 

4. For best viewing results in Acrobat Reader 5.0, use the Edit menu to access the Preferences. 

Select General and open the Display preferences to activate the Smooth Line Art option. 

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