Netter's atlas of neurology (atlas of neuroanatomy & neurophysiology)

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 NeurophysiologySelections from the Netter Collection of Medical Illustrations

Copyright ©2002 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.Neither the publisher nor the authors can be held responsible for errors or for anyconsequences 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 drawnfrom the Atlas of Human Anatomy and Netter’s Atlas of Human Physiology. Viewing these picturesagain 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 atNew 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, allow-ing him to augment his income by illustrating articles and textbooks. He continued illustrating as asideline after establishing a surgical practice in 1933, but ultimately opted to give up his practice infavor of a full-time commitment to art. After service in the United States Army during the SecondWorld War, Dr. Netter began his long collaboration with the CIBA Pharmaceutical Company (nowNovartis Pharmaceuticals). This 45-year partnership resulted in the production of the extraordinarycollection 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 onlysecondarily on Netter the physician. As a student of Dr. Netter’s work for more than forty years, I cansay that the true strength of a Netter illustration was always established well before brush was laid topaper. In that respect each plate is more of an intellectual than an artistic or aesthetic exercise. It iseasy to appreciate the aesthetic qualities of Dr. Netter’s work, but to overlook its intellectual quali-ties is to miss the real strength and intent of the art. This intellectual process requires thorough under-standing of the topic, as Dr. Netter wrote: “Strange as it may seem, the hardest part of making a med-ical picture is not the drawing at all. It is the planning, the conception, the determination of point ofview 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 agood medical illustration can include clinical information and physiologic functions as well as anato-my. In pursuit of this principle Dr. Netter often integrates pertinent basic and clinical science ele-ments in his anatomic interpretations. Although he was chided for this heresy by a prominentEuropean anatomy professor, many generations of students training to be physicians rather thananatomists 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’scareer depict anatomy clearly based on cadaver specimens with renderings of shrunken and shriv-eled tissues and organs. Netter the physician chose to render “live” versions of these structures—notshriveled, 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, MDAustin, 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 mono-

graphs 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 Pharmaceuticals has commis-

sioned 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 NeuroanatomyCerebrum—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

2

NEUROANATOMY Cerebrum: Medial Views

Cingulate gyrus

Cingulate sulcus

Medial frontal gyrus

Sulcus of corpus callosum

Fornix

Septum pellucidum

Central sulcus (Rolando)

Sagittal section of brain in situ

Interventricularforamen (Monro)

Interthalamicadhesion

Thalamus and3rd ventricle

Subcallosal(parolfactory)area

Anterior commissure

Subcallosalgyrus

Hypothalamicsulcus

Laminaterminalis

Supra- optic recess

Paracentral sulcus

Paracentral lobule

Corpus callosum

Precuneus

Superior sagittal sinus

Choroid plexusof 3rd ventricle

Stria medullarisof thalamus

Parietooccipitalsulcus

Habenularcommissure

Cuneus

Pineal body

Posteriorcommissure

Calcarinesulcus

Straight sinusin tentoriumcerebelli

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

Hypophysis (pituitary gland)

Mammillary body

Cerebral peduncle

Pons Cerebral aqueduct (Sylvius)

GenuRostrumTrunkSplenium

ofcorpus callosum

Isthmus of cingulate gyrus

Parietooccipital sulcus

Cuneus

Calcarine sulcus

Lingual gyrus

CrusBodyColumn

of fornix

Fimbria of hippocampus

Dentate gyrus

Parahippocampal gyrusLateral occipitotemporal gyrus

Occipitotemporal sulcus

Medial occipitotemporal gyrus

Rhinal sulcus

Collateral sulcus

Olfactory tract

Optic nerve (II)

Uncus

Mammillary body

Mammillothalamicfasciculus

Cingulate gyrus

Medial surface of cerebralhemisphere: brainstem excised

Tuber cinereum

Optic chiasm

Marginal sulcus

3

NEUROANATOMYCerebrum: Inferior View

Sectioned brainstem Frontal pole of cerebrum

Straight gyrus

Olfactory sulcus

Orbital sulci

Orbital gyri

Temporal pole

Lateral sulcus (Sylvius)

Inferior temporal sulcus

Inferior temporal gyrus

Rhinal sulcus

Uncus

Collateral sulcus

Parahippocampal gyrus

Medial occipitotemporal gyrus

Calcarine sulcus

Isthmus of cingulate gyrus

Longitudinal cerebral fissure

Occipital pole of cerebrum

Apex of cuneus

Splenium of corpus callosum

Cerebral aqueduct

Pulvinar of thalamus

Red nucleus

Substantia nigra

Cerebral crus

Mammillary body

Tuber cinereum

Optic tract

Optic nerve (II) (cut)

Optic chiasm


Genu of corpus callosum

Lamina terminalis

Olfactory bulb

Olfactory tract

Posterior perforated substance (in interpeduncular fossa)

Inferior (infero-lateral) marginof cerebrum


Anterior perforated substance

Superior colliculus (of corpora quadrigemina)

Medial geniculate body

Lateral geniculate body

Inferiortemporal gyrus

Occipitotemporal sulcus

Lateral occipito-temporal gyrus

4

NEUROANATOMY Basal Nuclei (Ganglia)

Horizontal sections through cerebrum


Lateral ventricle

Septum pellucidum

Column of fornix

Insula(island of Reil)


Thalamus

Crus of fornix

Choroid plexusof lateral ventricle


Head of caudate nucleus

Anterior limb

Genu

Posterior limb

Putamen

Globus pallidus

3rd ventricle

External capsule

Claustrum

Retrolenticular partof internal capsule

Tail of caudate nucleus

Hippocampus and fimbria

Occipital (posterior) hornof lateral ventricle

Habenula

Pineal body

Cleft for internal capsule

Organization ofbasal nuclei (ganglia)

Caudatenucleus

Putamen Globuspallidus

StriatumLentiformnucleus

Corpus striatum

Basal nuclei(ganglia)

Caudatenucleus

Levels ofsectionsabove

Body

Head

Lentiform nucleus(globus pallidus medialto putamen)

Thalamus

Pulvinar



Tail of caudate nucleusAmygdaloid body

A

Interrelationship of thalamus, lentiform nucleus, caudatenucleus and amygdaloid body (schema): left lateral view

B

A B

A B

of internalcapsule

Lentiformnucleus

A

B

5

NEUROANATOMYThalamus

Interventricular foramen (Monro)

3rd ventricle

Corpus callosum (cut)


Septum pellucidum

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

Choroid plexus

Superior thalamostriate vein

Pes hippocampi

Internal cerebral vein

Dentate gyrus

Collateral eminence

Hippocampus


Posterior commissure

Habenular commissure

Pineal body

Collateral trigone

Calcar avis

Tela choroidea (cut edge)of 3rd ventricle

Temporal (inferior) hornof lateral ventricle

Occipital (posterior) hornof lateral ventricle

Calcarine sulcus

Superior colliculus

Inferior colliculus

Cerebellum

Pulvinar

Reticular nucleus

Median nuclei

3rd ventricle

Pulvinar



3rd ventricleInterthalamicadhesion

Intralaminarnuclei

Externalmedullarylamina

Internalmedullarylamina

Schematic sectionthrough thalamus

(at level of brokenline shown in figureat right)

Thalamic nuclei

CM CentromedianLD Lateral dorsalLP Lateral posteriorM MedialMD Medial dorsalVA Ventral anteriorVI Ventral intermedialVL Ventral lateralVP Ventral posteriorVPL Ventral posterolateralVPM Ventral posteromedial

Lateral nuclei

Medial nuclei

Anterior nuclei

Schematic representation of thalamus

(external medullary lamina andreticular nuclei removed)

MD

M

CM

VPL

VPM

LP

LP

LD

VP

VPLVPM

VI

VL

VAMedian

Medial

lamina

medullary

Internal

Anterior

Lam

ina

6

NEUROANATOMY Cerebellum

Anterior cerebellar notch

Central lobule (II & III)

Culmen (IV & V)

Declive (VI)

Folium (VII A)

Superior vermis

Posterior cerebellar notch

Superior surface

Superiorvermis

Inferior surfaceCentral lobule

Lingula (I)


Flocculus (H X)

4th ventricle


Nodule (X)

Uvula (IX)

Pyramid (VIII)

Tuber (VII B)

Posterior cerebellar notch

Inferiorvermis

4th ventricle


Fastigial

Globose

Dentate

Emboliform

Decussation ofsuperior cerebellar peduncles

Cerebellarnuclei

Section in plane of superior cerebellar peduncle

Cerebral crus

Medial longitudinal fasciculus

Lingula (I)

Vermis

Nuclear layer ofmedulla oblongata

Superior cerebellarpeduncle

Secondary (postpyramidal)fissure

Posterolateral (dorsolateral)fissure

Flocculonodular lobe

Posterior lobe

Retrotonsillar fissure

Tonsil

Biventer lobule (H VIII)

Horizontal fissure

Inferior semilunar (caudal) lobule (H VII B)

Anterior lobe

Wing of central lobule

Superior

Middle

InferiorCerebellar peduncles

Anterior lobe

Quadrangular lobule (H IV-V)

Primary fissure

Horizontal fissure

Simple lobule (H VI)

Posterior lobe

Postlunate fissure

Horizontal fissure

Superior semilunar(anseriform) lobule (H VII A)

Inferior semilunar (caudal) lobule (H VII B)

7

NEUROANATOMYBrainstem

Pulvinars of thalami

Posterolateral view

Pineal body

Superior colliculi

Inferior colliculi

Trochlear nerve (IV)


Superior cerebellar peduncle

Cuneate tubercle

Gracile tubercle

Cuneate fasciculus

Gracile fasciculus

Rhomboid fossa of4th ventricle

Glossopharyngeal (IX) andvagus (X) nerves

Dorsal roots of1st spinal nerve (C1)

Anterior view

Optic chiasm

Optic tract

Tuber cinereum

Cerebral crus


Pons

Olive

Pyramid

Ventral roots of 1st spinal nerve (C1)

Decussation of pyramids

Middle cerebellar peduncle

Posterior perforated substance

Olfactory tract


Infundibulum (pituitary stalk)

Mammillary bodies

Temporal lobe (cut surface)

Oculomotor nerve (III)


Trigeminal nerve (V)

Abducent nerve (VI)

Vestibulocochlear nerve (VIII)

Flocculus of cerebellum

Glossopharyngeal nerve (IX)

Vagus nerve (X)

Hypoglossal nerve (XII)

Accessory nerve (XI)

Facial nerve (VII) andintermediate nerve

Choroid plexus of 4thventricle

Thalamus (cut surface)


Optic tract


Brachia of superior and inferior colliculi

Cerebral crus

Pons



Vestibulocochlear nerve (VIII)

Facial nerve (VII)

Inferior cerebellar peduncle

Hypoglossal nerve (XII)

Accessory nerve (XI)

8

NEUROANATOMY Fourth Ventricle and Cerebellum

Posterior view

3rd ventricle


Pineal body

Superior colliculus

Inferior colliculus



Cerebellar peduncles

Lateral recess

Superior fovea

Sulcus limitans

Inferior fovea

Trigeminal tubercle

Hypoglossal trigone

Vagal trigone

Obex

Gracile fasciculus


Posterior commissure

Habenular commissure

Pineal body


Great cerebral vein (Galen)

Cuneate fasciculus

Lateral funiculus

Dorsal median sulcus

Gracile tubercle

Habenular trigone

Geniculate bodies

Dorsal median sulcus


Locus ceruleus

Medial eminence

Facial colliculus

Vestibular area

Striae medullares

Tenia of 4th ventricle

Cuneate tubercle

SuperiorMiddleInferior

MedialLateral

Dentate nucleusof cerebellum

Lingula (I)

Central lobule (II-III)

Culmen (IV-V)

Declive (VI)

Folium (VII A)

Tuber (VII B)

Pyramid (VIII)

Uvula (IX)

Nodulus (X)

Choroid plexus of 4th ventricle

Tonsil of cerebellumCentral canal of spinal cord

Medulla oblongata


4th ventricle

Medial longitudinal fasciculus

Pons

Inferior colliculus

Tectal (quadrigeminal) plate

Superior colliculus

Cerebral aqueduct (Sylvius)

Cerebral peduncle

Hypothalamic sulcus

Lamina terminalis

Anterior commissure

Body of fornix

Decussation of pyramids

Median aperture (foramen of Magendie)



Vermis ofcerebellum

Vermis ofcerebellum


Thalamus (in3rd ventricle)

Median sagittal section

9

NEUROANATOMYAccessory Nerve (XI): Schema

Nucleus ambiguus

Vagus nerve (X)

Cranial root of accessory nerve (joins vagus nerveand via recurrent laryngeal nerve supplies muscles oflarynx, except cricothyroid)*

Spinal root ofaccessory nerve

Foramenmagnum

Jugular foramen

Superior ganglionof vagus nerve

Accessory nerve (XI)*

Inferior ganglionof vagus nerve

C1 spinal nerve

C2 spinal nerve

Accessory nerve(to sternocleidomastoidand trapezius muscles)

Sternocleidomastoid muscle (cut)

C3 spinal nerve

C4 spinal nerve

Trapezius muscle

Efferent fibers

Proprioceptive fibers

*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.

10

NEUROANATOMY Arteries to Brain and Meninges

Left middle meningeal artery

Posterior cerebral artery

Superior cerebellar artery

Basilar artery

Left labyrinthine(internal acoustic) artery

Mastoid branch ofleft occipital artery

Anterior inferiorcerebellar artery

Posterior inferiorcerebellar artery

Posterior meningealbranch of left ascendingpharyngeal artery

Left and rightvertebral arteries(intracranial part)

Posterior meningealbranch of vertebralartery

Anterior meningealbranch of vertebral artery

Posterior auricular artery

Occipital artery

Internal carotid artery

Carotid sinus

Carotid body

Vertebral artery(cervical part)

Transverse process of C6

Deep cervical artery

Supreme intercostalartery

Costocervical trunk

Subclavian artery

Middle cerebral artery

Anterior cerebral artery

Anterior communicating artery

Ophthalmic artery

Posteriorcommunicatingartery

Cavernous sinus

Middle meningealartery

Maxillaryartery

Superficialtemporalartery

Externalcarotidartery

Facial artery

Lingual 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

11

NEUROANATOMYArteries to Brain: Schema

Ophthalmic artery

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

Anterior spinal artery

Spinal segmental medullary branches

Vertebral artery


Deep cervical artery

Transverse cervical artery

Subclavian artery

Internal thoracic artery

Suprascapular artery

Supreme intercostal artery

Costocervical trunk


Anastomoses

1 Right–Left

2 Carotid–Vertebral

3 Internal carotid–External carotid

4 Subclavian–Carotid

5 Subclavian–Vertebral

Vertebral artery

Ascending cervical artery


Thyrocervical trunk

Subclavian artery

Brachiocephalic trunk

Aorta

Arch

Descending

Ascending

Middle meningeal artery

Anterior tympanic artery




Posterior communicating artery


Maxillary artery

Basilar artery

External carotid artery


Superior thyroid artery


Anterior inferiorcerebellar artery

Posterior inferiorcerebellar artery

5

5

5

5

55

54

4

33

3

3

1

1

2

5

11

Caroticotympanic branchof internal carotid artery

12

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




Basilar artery

Pontine arteries

Labyrinthine (internal acoustic) artery

Anterior inferior cerebellar artery

Vertebral artery


Posterior inferior cerebellar artery (PICA) (cut)

Posterior spinal artery

Cerebral arterialcircle (Willis)(broken line)


Distal medial striate artery(recurrent artery of Heubner)





Optic tract


Cerebral crus


Posterior medial choroidal artery

Posterior lateral choroidal artery

Choroid plexus of lateral ventricle



Lateral ventricle

13

NEUROANATOMYCerebral Arterial Circle (Willis)

Vessels dissected out: inferior view

Anterior cerebral artery (A2 segment)


Anterior cerebral artery (A1 segment)

Ophthalmic artery




Posterior cerebral artery (P2 segment)(P1 segment)


Basilar artery

Pontine arteries


Anteromedial central (perforating)arteries

Hypothalamic artery


Anterolateral central(lenticulostriate) arteries

Superior hypophyseal artery

Inferior hypophyseal artery


Thalamotuberal(premammillary) artery

Posteromedial central (perforating) arteries

Thalamoperforating artery

Posteromedial central (paramedian) arteries


Vertebral artery

Vessels in situ: inferior view


Hypothalamic artery


Superior hypophyseal artery




Efferent hypophyseal veins



Optic chiasm

Cavernous sinus

Infundibulum (pituitary stalk) and long hypophyseal portal veins

Adenohypophysis (anterior lobe of pituitary gland)

Neurohypophysis (posterior lobe of pituitary gland)

Posteromedial central (perforating) arteries


Basilar artery

14

NEUROANATOMY Arteries of Brain: Frontal View and Section

Corpus callosum

Prefrontal artery


Lateral frontobasal(orbitofrontal) artery

Anterior parietal(postcentral sulcal) artery

Precentral (pre-rolandic) and central (rolandic) sulcal arteries

Posterior parietal artery

Branch to angular gyrus


Temporal branches(anterior, middleand posterior)

Middle cerebral arteryand 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) sulcaland parietal arteries

Lateral cerebral (sylvian) sulcus

Temporal branches ofmiddle cerebral artery

Temporal lobe



Paracentral artery

Medial frontal branches

Pericallosal artery

Callosomarginal artery

Polar frontal artery

Anterior cerebralarteries

Medial frontobasal(orbitofrontal) artery

Distal medial striateartery (recurrent artery of Heubner)


Anterior choroidalartery

Posterior cerebralartery


Basilar and pontine arteries

Labyrinthine (internalacoustic) artery

Vertebral artery

Posterior inferior cerebellar artery


Falx cerebri

Callosomarginal arteriesandPericallosal arteries(branches of anteriorcerebral arteries)

Trunk of corpus callosum

Internal capsule

Septum pellucidum

Rostrum of corpus callosum

Anterior cerebral arteries



Optic chiasm

15

NEUROANATOMYArteries of Brain: Lateral and Medial Views

Anterior parietal (postcentral sulcal) artery

Central (rolandic) sulcal artery

Precentral (pre-rolandic) sulcal artery

Prefrontal sulcalartery

Terminal branches ofanterior cerebralartery

Lateral frontobasal(orbitofrontal) artery

Left middlecerebral artery

Left anteriorcerebral artery


Right anterior cerebral artery

Left internal carotid artery

Pericallosal arteryPosterior

Intermediate

Anterior

Medialfrontalbranches

Callosomarginalartery

Polar frontal artery

Right anteriorcerebral artery

Medial fronto-basal (orbito-frontal) artery

Anterior communicating artery (cut)

Distal medial striate artery(recurrent artery of Heubner)

Right internal carotid artery

Posterior parietal artery

Branch to angular gyrus

Terminal branchesof posteriorcerebral artery

Posterior temporal branch

Middle temporal branch

Superior and inferior terminal branches (trunks)

Anterior temporal branch

Paracentral artery

Cingular branches

Right posterior cerebral artery

Precuneal artery

Dorsal branch to corpus callosum

Parietooccipital branch

Calcarine branch

Posterior temporal branch

Anterior temporal branch


Polar temporal artery

Medial occipital artery

Occipitotemporalbranches

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

16

NEUROANATOMY Arteries of Posterior Cranial Fossa

Thalamogeniculate arteries


Crura of fornix


Heads of caudate nuclei

Septum pellucidum

Corpus callosum

Anteriorcerebral arteries

Longitudinalcerebralfissure

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

Calcarine

Branches ofright posteriorcerebral artery

Optic nerve (II)

Ophthalmic artery

Thalamoperforating arteries

Anteriorcerebral artery

Middlecerebral artery

Posteriorcommunicating artery

Left internal carotid artery

Basilar artery

Pontine arteries




Anterior meningeal branch of vertebral artery


Temporal branches of posterior cerebral artery


Superiorcolliculi

Posterior medialchoroidal arteryto choroid plexusof 3rd ventricle

Posterior lateralchoroidal artery

Lateral (marginal) branch

Inferior vermian artery(phantom)

Choroidal branch to 4th ventricle(phantom) andCerebellar tonsillar branchof 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

IIIIV

V

VIII

VII

VIIX

X

XI

Superiorvermianbranch

17

NEUROANATOMYVeins of Posterior Cranial Fossa

Parts of cerebellum

L Lingula TU TuberCL Central lobule P PyramidC Culmen U UvulaD Declive N NoduleF Folium T Tonsil

Left superior and inferior colliculi

Basal vein (Rosenthal)

Posterior mesencephalic vein



Optic tract

Left thalamus(cut surface)

Inferior thalamo-striate veins

Optic nerve (II)

Lateralmesencephalic vein

Deep middlecerebralvein (cut)

Anteriorcerebralvein

Anterior ponto-mesencephalic vein

Petrosal vein (drainingto superior petrosal sinus)

Superior, middle andinferior cerebellar peduncles


Transverse pontine vein

Lateral pontine vein

Anteromedian medullary vein

Vein of lateral recess of 4th ventricle

Anterior spinal vein 4th ventricle

Confluence of sinuses

Left transversesinus (cut)

Superiorsagittalsinus

Left pulvinar

Right pulvinar

Internal cerebral veins

Dorsal vein of corpus callosum

Inferior sagittal sinus

Straight sinus

Falx cerebri



Tentoriumcerebelli (cut)

CC

D

F

TU

P

U

T

CL

L

N

Superiorvermianvein

Inferiorvermian vein

Falx cerebelli (cut)and occipital sinus

Inferior cerebellarhemispheric veins

Posterior spinal vein

Precentral cerebellar vein

Preculminate vein

Intraculminate vein

Superior cerebellar vein (inconstant)

(Inferior retrotonsillar) vein of cerebellomedullarycistern

Superior retrotonsillar vein

18

NEUROANATOMY Deep Veins of Brain


Anterior cerebral veins

Septum pellucidum

Anterior vein of septum pellucidum


Anterior vein of caudate nucleus

Transverse veins of caudate nucleus

Interventricular foramen (Monro)

Columns of fornix


Rostrum of corpus callosum

Superior choroid vein andchoroid plexus of lateral ventricle

Thalamus

Tela choroidea of 3rd ventricle

Lateral direct vein

Posterior vein of caudate nucleus

Internal cerebral veins



Inferior sagittal sinus

Straight sinus

Tentorium cerebelli

Transverse sinus

Confluence of sinuses


Dissection: superior view

Dissection: inferior view

Uncal vein

Optic chiasm

Inferiorcerebralveins

Inferioranastomoticvein (Labbé)

Anterior cerebral vein

Deep middle cerebral vein

Cerebral crus







Superficial middle cerebral vein(draining to sphenoparietal sinus)

19

NEUROANATOMYSubependymal Veins of Brain

Lateral direct vein

Superior thalamic veins

Posterior veins of septum pellucidum

Superior choroid vein

Transverse veins of caudate nucleus


Lateral ventricle

Anterior vein ofcaudate nucleus

Anterior vein ofseptum pellucidum

Genu ofcorpuscallosum


Anterior commissure


Anterior cerebral vein

Optic chiasm

3rd ventricle

Deep middle cerebral vein

Inferior thalamostriate veins


Temporal (inferior) horn of lateral ventricle

Posterior mesencephalic vein

Hippocampal and inferior ventricular veins

Cerebral aqueduct

4th ventricle

Lateral and median apertures of 4th ventricle

Veins on lateral wall of ventricle

Veins on medial wall and floor of ventricle

All other veins

Cerebellum

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 corpuscallosum

Inferior sagittalsinus

Internaloccipital vein

Straight sinus

Occipital(posterior)horn oflateralventricle

Superior vermian vein

20

NEUROANATOMY Hypothalamus and Hypophysis

Septum pellucidum

Thalamus

Fornix

Hypothalamic sulcus

Anterior commissure

Paraventricular

Posterior

Dorsomedial

Supraoptic

VentromedialArcuate(infundibular)

Mammillary

Principalnuclei ofhypothalamus

Optic chiasm



Mammillothalamic tract

Dorsal longitudinalfasciculus and otherdescending pathways

Lamina terminalis

Paraventricular hypothalamic nucleus

Supraoptic hypothalamic nucleus

Supraopticohypophyseal tract

Tuberohypophyseal tract

Hypothalamohypophyseal tract


Fibrous trabecula

Pars intermedia

Pars distalis

Cleft

Pars tuberalis

Adenohypophysis(anterior lobe ofpituitary gland)

Hypothalamicsulcus

Mammillarybody

Arcuate (infundibular) nucleus

Median eminenceof tuber cinereum

Infundibularstem

Infundibularprocess

Neurohypophysis(posterior lobeof pituitary gland)

21

NEUROANATOMYArteries and Veins of Hypothalamus and Hypophysis

Primary plexus ofhypophyseal portal system

Efferent hypophyseal veinto cavernous sinus

Capillary plexus ofinfundibular process


Long hypophyseal portal veins

Artery of trabecula

Trabecula (fibrous tissue)

Short hypophyseal portal veins

Neurohypophysis(posterior lobe ofpituitary gland)

Superiorhypophysealartery

Secondary plexusof hypophysealportal system

Hypothalamic vessels

Efferent hypophysealveins to cavernous sinus


Adenohypophysis(anterior lobe ofpituitary gland)


22

NEUROANATOMY Relation of Spinal Nerve Roots to Vertebrae

C1 spinal nerve exitsabove C1 vertebra

Cervicalenlargement

Base of skull

C8 spinal nerveexits belowC7 vertebra(there are 8 cervicalnerves but only7 cervical vertebrae)

Lumbar disc protrusion does not usually affectnerve exiting above disc. Lateral protrusionat disc level L4–5 affects L5 spinal nerve, notL4 spinal nerve. Protrusion at disc level L5–S1affects S1 spinal nerve, not L5 spinal nerve

Lumbarenlargement

Conus medullaris(termination ofspinal cord)

Internal terminal filum (pial part)

External terminal filum (dural part) Termination of

dural sac

Cauda equina

Coccygeal nerve

Coccyx Coccygeal nerve

Cervical nerves

Thoracic nerves

Lumbar nerves

Sacral and coccygeal nerves

Medial protrusion at disc level L4–5 rarely affectsL4 spinal nerve but may affect L5 spinal nerveand sometimes S1–4 spinal nerves

C1

C2

C3

C4

C5

C6

C7

T1

T2

T3

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

C1

C2

C3

C4

C5C6

C7

C8

T1

T2

T3

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2L2

L3

L5

L3

L4

L4

L5

Sacrum

S1S2

S3

S4

S5

S2

L4

L4

L5

L5

S1

L4

L4

L5

L5

S1

S2

S3

S4

S5

23

NEUROANATOMYAutonomic Nervous System: General Topography


Facial nerve (VII)


Vagus nerve (X)

Internal carotid nerve and plexus

Superior cervical sympathetic ganglion

C4 spinal nerve

Middle cervical sympathetic ganglion

Vertebral ganglion

Cervicothoracic (stellate) ganglion

Sympathetic trunk

Cervical (sympathetic)cardiac nerves

Superior

Middle

Inferior

Thoracic (sympathetic) cardiac nerves

6th intercostal nerve(ventral ramus of T6spinal nerve)

Sympathetic trunk

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 parasympatheticoutflow)

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 branchesof vagus nerve

Recurrent laryngeal branch of vagus nerve

Superior cervicalInferior cervicalThoracic

Cardiac branchesof vagus nerve

Cardiac plexus

AnteriorPosterior

Pulmonary plexuses

Esophageal plexus

Thoracic aortic plexus

Anterior vagal trunk

Posterior vagal trunk

Celiac ganglion

Celiac trunk and plexus

Superior mesenteric ganglion

Superior mesenteric arteryand plexus

Intermesenteric(abdominal aortic) plexus

Inferior mesenteric ganglion

Inferior mesenteric arteryand plexus

Superior hypogastric plexus

Parasympathetic branch frominferior hypogastric plexus todescending colon

Hypogastric nerves

Rectal plexus

Vesical plexus

Prostatic plexus

24

NEUROANATOMY Spinal Nerve Origin: Cross Sections

Section through thoracic vertebra

Fat in epidural space

Sympathetic ganglion

Ventral root

White and gray ramicommunicantes

Spinal nerve

Ventral ramus(intercostal nerve)

Dorsal ramus

Aorta

Dura mater

Subarachnoid space

Arachnoid mater*

Pia mater*

Recurrentmeningealbranches ofspinal nerve

Pleura

Lung

Spinal sensory (dorsal root) ganglion

Dorsal root

Dura mater

Arachnoid mater

Ventral root

Spinal nerve

Ventral ramus (contributes to lumbar plexus)

Dorsal ramus


Dorsal root

Conus medullaris

*Leptomeninges

Dorsal and ventralroots of lumbar andsacral spinal nervesforming cauda equina

Gray ramuscommunicans

Fat inepiduralspace

Sympatheticganglion

Section through lumbar vertebra

Lateral branch

Medial branch

of dorsal ramus of spinal nerve

Lateral horn of gray matter of spinal cord

Body of vertebra

Internal vertebral (epidural) venous plexus

25

NEUROANATOMYOlfactory Nerve (I): Schema

Olfactory bulb cells: schema

Efferent fibers toolfactory bulb

Afferent fibers from bulbto central connectionsand contralateral bulb

Granule cell (excited byand inhibiting to mitraland tufted cells)

Mitral cell

Recurrent process

Tufted cell

Periglomerularcell

Glomerulus

Subcallosal (parolfactory) area

Olfactorynerve fibers

Septal area and nuclei

Fibers from

Fibers to

Contralateralolfactory bulb

Anterior commissure

Medial olfactory stria

Olfactory cells

Olfactory mucosa

Olfactory nerves (I)

Olfactory bulb

Cribriform plate of ethmoid bone

Anterior olfactory nucleus

Olfactory tract

Olfactory trigoneand olfactory tubercle

Lateral olfactory stria

Lateral olfactory tract nucleus


Amygdaloid body (phantom)

Piriform lobe

Uncus

Hippocampalfimbria

Dentate gyrus

Parahippocampal gyrus

26

NEUROANATOMY Optic Nerve (II) (Visual Pathway): Schema

Overlappingvisual fields

Projection onleft retina

Choroid Choroid

Periphery Macula

Projection onright retina

Central darkercircle representsmacular zone

Lighter shadesrepresentmonocular fields

Each quadranta different color

Projection on rightdorsal lateralgeniculate nucleus

Optic nerves (II)

Optic chiasm

Optic tracts

Projection on leftdorsal lateralgeniculate nucleus

Lateralgeniculatebodies

Optic radiation Optic radiation

Calcarinesulcus

Calcarinesulcus

Projection on leftoccipital lobe

Projection on rightoccipital lobe

Structure of retina: schema

A Amacrine cellsB Bipolar cellsC ConesG Ganglion cellsH Horizontal cellsP Pigment cellsR Rods

G

G

A

B

H

A

B

H

R R C C

P P

27

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

Long ciliary nerve

Short ciliary nerves

Anterior ethmoidal nerve

Superior oblique muscle

Levator palpebraesuperioris muscle

Superior rectus muscle

Ciliary ganglion

Posterior ethmoidal nerve

Sensory root of ciliary ganglion

Sympathetic root of ciliary ganglion

Superior division ofoculomotor nerve

Frontal nerve (cut)

Lacrimal nerve (cut)

Nasociliary nerve

Abducent nucleus

Trochlear nucleus

Oculomotor nucleus

Accessory oculomotor(Edinger-Westphal)nucleus (parasympathetic)



Ophthalmic nerve (V1)

Infraorbital nerve

Zygomatic nerve (cut)

Inferior oblique muscle

Ciliary muscle

Dilator muscle of pupil

Sphincter muscle of pupil

Pterygopalatineganglion

Inferior division ofoculomotor nerve

Medial rectus muscle

Inferior rectus muscle

Parasympathetic rootof ciliary ganglion

Efferent fibers

Afferent fibers

Sympathetic fibers


Abducentnerve (VI)

Mandibular nerve (V3)

Maxillary nerve (V2)

Internal carotid arteryand nerve plexus

Lateral rectus muscle andabducent nerve (turned back)

Cavernous plexus

Common tendinous ring

28

NEUROANATOMY Trigeminal Nerve (V): Schema

Efferent fibers

Afferent fibers



Sympathetic fibers

Ophthalmic nerve (V1)

Tentorial (meningeal) branch

Nasociliary nerve

Lacrimal nerve

Frontal nerve

Sensory root ofciliary ganglion

Ciliary ganglion

Posterior ethmoidal nerve

Long ciliary nerve

Short ciliary nerves

Anterior ethmoidal nerve

Supraorbital nerve

Supratrochlear nerve

Infratrochlear nerve

Internal nasal branchesandExternal nasal branchesof anterior ethmoidal nerve

Maxillary nerve (V2)

Meningeal branch

Zygomaticotemporalnerve

Zygomaticofacial nerve

Zygomatic nerve

Infraorbital nerve

Pterygopalatineganglion

Superioralveolarbranches ofinfraorbital nerve

Nasal branches(posterior superiorlateral, nasopalatineand posteriorsuperior medial)

Nerve (vidian) ofpterygoid canal(from facial nerve [VII]and carotid plexus)

Pharyngeal branch

Greater and lesserpalatine nerves

Deep temporal nerves(to temporalis muscle)

Lateral pterygoidand masseteric nerves

Tensor veli palatini andmedial pterygoid nerves

Buccal nerve

Mental nerve

Inferior dental plexus

Lingual nerve

Submandibularganglion

Mylohyoid nerve


Inferioralveolar nerve

Otic ganglion

Tensor tympani nerve

Chordatympani nerve

Superficial temporal branches

Articular branch and anterior auricular nerves

Auriculotemporal nerve

Parotid branches

Meningeal branch

Lesser petrosal nerve (fromglossopharyngeal nerve [IX])

Facial nerve (VII)

Trigeminal nerve (V) ganglion and nuclei

Motor nucleusMesencephalic nucleus

Principal sensory nucleusSpinal tract and nucleus

29

NEUROANATOMYFacial Nerve (VII): Schema

Greater petrosal nerve

Deep petrosal nerve (from internal carotid plexus)

Lesser petrosal nerve

Nerve (vidian) of pterygoid canal

Otic ganglion


Facial muscles

Orbicularis oculi

Frontal belly (frontalis)of occipitofrontalis

Corrugator supercilii

Zygomaticus major

Zygomaticus minor

Procerus

Nasalis

Facial nerve (VII)

Levator labiisuperioris

Levatoranguli oris

Levator labiisuperiorisalaeque nasi

Tem

po

ral

bra

nc

he

s

Zygomatic

Mentalis

Depressorsepti nasi

Orbicularisoris

Depressoranguli oris

Depressor labiiinferioris

(Risorius)(not shown)

Buccinator

Platysma

Buccalbranches

Marginal

mandibular

branch

anterior 2⁄3tongueTaste:

of

Efferent fibers

Afferent fibers


Sympathetic fibers

Sublingual gland

Submandibular gland


Lingual nerve (from trigeminal nerve)

Chorda tympani nerve Caroticotympanic nerve (from internal carotid plexus)

Stylohyoid muscle

Digastric muscle (posterior belly)


Tympanic nerve (Jacobson)(from glossopharyngeal nerve)

Tympanic plexus

Stylomastoid foramen

Nerve to stapedius muscle

Posterior auricular nerve

Branches to auricular muscles

Occipitalbranch ofposteriorauricularnerve

Ce

rvic

al b

ran

ch

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

Occipitalbelly(occipitalis) ofoccipitofrontalismuscle

branches

30

NEUROANATOMY Vestibulocochlear Nerve (VIII): Schema

Afferent fibers

Geniculum of facial nerve(site of geniculate ganglion)

Facial canal


Cochlear (spiral) ganglion

Vestibular nerve

Cochlear nerve

Tympanic cavity

Chorda tympani nerve

Motor root of facial nerveand intermediate nerve

Vestibulocochlearnerve (VIII)

Medulla oblongata(cross section)

Internal acousticmeatus

Medial

Superior

Inferior

Lateral

Vestibularnuclei(diagrammatic)

Anterior

Posterior

Cochlearnuclei

Inferior cerebellarpeduncle (to cerebellum)

Vestibular ganglionInferior division

Superior division

Saccule

Ampulla of posteriorsemicircular duct

Utricle

Ampulla of superiorsemicircular duct

Ampulla of lateralsemicircular duct

of vestibular nerve

Head of malleus

Incus

31

NEUROANATOMYGlossopharyngeal Nerve (IX): Schema

Efferent fibers

Afferent fibers

Parasympathetic fibers Tympanic nerve (Jacobson)

Tympanic cavity and plexus

Stylomastoid foramen

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 from glossopharyngeal nerve)

Spinal tract and spinal nucleus of trigeminal nerve

Solitary tract nucleus

Nucleus ambiguus

Inferior salivatory nucleus

Geniculate ganglionof facial nerve

Glossopharyngealnerve (IX)

Jugular foramen

Communication to auricularbranch of vagus nerve

Superior andInferior ganglia ofGlossopharyngeal nerve

Communication to facial nerve (VII)

Vagus nerve (X)

Superior cervicalsympathetic ganglion

Sympathetic trunk

Carotid branch ofglossopharyngeal nerve


Carotid sinus

Carotid body


External carotid artery

Taste and somaticsensation:posterior1⁄3 of tongue

Pharyngeal plexus

Pharyngeal, tonsillar and lingualbranches of glossopharyngeal nerve

Pharyngeal branch of vagus nerve

32

NEUROANATOMY Vagus Nerve (X): Schema

SEE ALSO PLATE 160Glossopharyngeal nerve (IX)

Meningeal branch of vagus nerve

Auricular branch of vagus nerve

Pharyngotympanic (auditory) tube

Levator velipalatini muscle

Salpingopharyngeusmuscle

Palatoglossus muscle

Palatopharyngeusmuscle

Superior pharyngealconstrictor muscle

Stylopharyngeus muscle

Middle pharyngeal constrictor muscle

Inferior pharyngeal constrictor muscle

Cricothyroid muscle

Trachea

Esophagus

Right subclavian artery

Right recurrent laryngeal nerve

Heart

Cranial root ofaccessory nerve* (see next plate)

Posterior nucleus of vagus nerve (parasympathetic and visceral afferent)

Spinal tract and spinalnucleus of trigeminal nerve(somatic afferent)

Solitary tract nucleus (visceralafferents including taste)

Nucleus ambiguus(motor to pharyngealand laryngeal muscles)

Vagus nerve (X)

Jugular foramen

Superior ganglion of vagus nerve

Inferior ganglion of vagus nerve

Pharyngeal branch of vagus nerve (motor to muscles ofpalate and lower pharynx; sensory to lower pharynx)

Communicating branch of vagus nerve tocarotid 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 larynxexcept cricothyroid; sensory and parasympathetic tolarynx below vocal folds; parasympathetic, efferent andafferent to upper esophagus and trachea)

Pulmonary plexus

Hepatic branch of anteriorvagal trunk (in lesser omentum)

Celiac branches from anteriorand posterior vagal trunksto celiac plexus

Celiac and superior mesentericganglia and celiac plexus

Hepatic plexusCardiac plexus

Esophageal plexusGallbladderand bile ducts

Liver

Pyloric branchfrom hepatic plexus

Pancreas


Gastric branches of anterior vagal trunk(branches from posterior trunk behind stomach)

Duodenum

Ascending colon

Vagal branches (parasympathetic motor,secretomotor and afferent fibers) accompanysuperior mesenteric artery and its branchesusually as far as left colic (splenic) flexure

Small intestine

Cecum

Appendix

Efferent fibers

Afferent fibers


33

NEUROANATOMYAccessory Nerve (XI): Schema

SEE ALSO PLATE 28

Nucleus ambiguus

Vagus nerve (X)

Cranial root of accessory nerve (joins vagus nerveand via recurrent laryngeal nerve supplies muscles oflarynx, except cricothyroid)*

Spinal root ofaccessory nerve

Foramenmagnum

Jugular foramen

Superior ganglionof vagus nerve

Accessory nerve (XI)*

Inferior ganglionof vagus nerve

C1 spinal nerve

C2 spinal nerve

Accessory nerve(to sternocleidomastoidand trapezius muscles)

Sternocleidomastoid muscle (cut)

C3 spinal nerve

C4 spinal nerve

Trapezius muscle

Efferent fibers


*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.

34

NEUROANATOMY Hypoglossal Nerve (XII): Schema

Intrinsicmusclesof tongue

Superior longitudinal

Transverseand vertical

Inferiorlongitudinal

Styloglossusmuscle

Meningeal branch

Hypoglossal nucleus

Occipital condyle

Inferior ganglion ofvagus nerve

Hypoglossal nerve (XII)(in hypoglossal canal)

Ventral rami ofC1, 2, 3 formansa cervicalisof cervical plexus

Superior cervicalsympatheticganglion

Superior root ofansa cervicalis


Inferior root of ansa cervicalis

Ansa cervicalis

Internal jugular vein


Sternothyroid muscle

Sternohyoid muscle

Omohyoid muscle(superior belly)

Genioglossusmuscle

Geniohyoid muscle

Hyoglossus muscle

Thyrohyoid muscle

Omohyoid muscle (inferior belly) Efferent fibers

Afferent fibers

35

NEUROANATOMYNerves of Heart

Vagus nerve (X)


(Conjoined sympathetic andvagal) superior cervical cardiac nerves

Middle cervicalsympathetic ganglion

Middle cervical(sympathetic) cardiac nerve

Phrenic nerve

Inferior cervical(vagal) cardiac nerve

Vertebral ganglion


Vertebral artery

Cervicothoracic(stellate) ganglion

Ansa subclavia

Recurrentlaryngeal nerve

Inferior cervical(sympathetic) cardiac nerves

Thoracic cardiac branchof vagus nerve

4th thoracicsympathetic ganglion

Thoracic (sympathetic)cardiac branches

Cardiac plexus

Phrenic nerve (cut)


Vagus nerve (X)

Superior cervical(sympathetic) cardiac nerve

Superior cervical(vagal) cardiac nerve

Middle cervicalsympathetic ganglion

Phrenic nerve

Middle cervical(sympathetic) cardiac nerve

Inferior cervical(vagal) cardiac nerve

Vertebral ganglion

Cervicothoracic(stellate) ganglion

Inferior cervicalsympatheticcardiac nerves

3rd thoracicsympathetic ganglion

Thoracic (sympathetic)cardiac branches

Thoracic cardiacbranch ofvagus nerve

Recurrent laryngealnerve

36

NEUROANATOMY Autonomic Nerves and Ganglia of Abdomen

Right sympathetic trunk

Thoracic duct

Right greaterand lessersplanchnicnerves

Right phrenic nerve

Inferior phrenicarteries and plexuses

Right greaterand lessersplanchnicnerves

Right suprarenalplexus

Right aortico-renal ganglion

Right leastsplanchnic nerve

Right renalartery and plexus

Rightsympathetic trunk

White and grayrami communicantes

Cisterna chyli

Gray ramus communicans

3rd lumbar ganglionof sympathetic trunk

2nd and 3rd lumbarsplanchnic nerves

Right ureter and plexus

Right testicular (ovarian)artery and plexus

4th lumbar splanchnic nerve

1st sacral ganglion of sympathetic trunk


Anterior,Posteriorvagal trunks

Left gastric arteryand plexus

Celiac ganglia

Left greater splanchnic nerve

Left lesser splanchnic nerve

Splenic arteryand plexus

Common hepaticartery and plexus

Superior mesentericganglion and plexus

Left aorticorenalganglion

Left sympathetictrunk

Intermesenteric(aortic) plexus

Inferior mesentericganglion

Left colic arteryand plexus

Inferior mesentericartery and plexus

Left common iliacartery and plexus

Superior rectalartery and plexus

Superior hypogastricplexus

Internal and externaliliac arteries andplexuses

Right and lefthypogastric nervesto inferior hypo-gastric (pelvic) plexus

Left sacral plexus

Pelvic splanchnicnerves

37

NEUROANATOMYNerves of Stomach and Duodenum

Right and left inferior phrenic arteries and plexuses

Anterior and posterior layers of lesser omentum

Branch from hepatic plexus tocardia via lesser omentum

Right greater splanchnicnerve

Hepatic branch of anterior vagal trunk


Celiac branch of posterior vagal trunk

Celiac branch of anterior vagal trunk

Left gastric artery and plexus

Anterior gastric branch of anteriorvagal trunk

Left greater splanchnic nerve

Left lesser splanchnicnerve

Splenic artery and plexus

Celiac ganglia and plexus

Plexus on gastro-omental(gastroepiploic) arteries

Plexus on inferior pancreaticoduodenal artery

Superior mesenteric artery and plexus

Plexus on first jejunal artery

Plexus on anterior superior and anteriorinferior pancreaticoduodenal arteries(posterior pancreaticoduodenal arteries and plexuses not visible in this view)

Right gastricartery and plexus

Hepatic plexus

Vagalbranchfrom hepaticplexustopyloricpart ofstomach

38

NEUROANATOMY Nerves of Stomach and Duodenum (continued)

Plexus on gastro-omental (gastroepiploic) arteries

Hepatic plexus

Right gastricartery andplexus

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


Greater, lesser and leastsplanchnic nerves

Left inferior phrenic artery and plexus


Aorticorenal ganglia

Splenic artery and plexus

Right phrenic nerve

Phrenic ganglion

Branch from right inferior phrenicplexus to cardia of stomach

Right and left inferior phrenicarteries and plexuses



Greater,Lesser,Leastsplanchnicnerves

Viewwithstomachreflectedcephalad

Plexus onanterior superiorand anterior inferiorpancreatico-duodenal arteries

Plexus on gastroduodenal artery

Plexus on posterior superiorand posterior inferiorpancreaticoduodenal arteries

Superior mesenteric ganglion and plexus

Superior mesenteric ganglion and plexus

Right greater,lesserand leastsplanchnic nerves

Celiac ganglia


Left aorticorenal ganglion

Left greater, lesser and leastsplanchnic nerves

Celiac branchesof anteriorand posteriorvagal trunks

Left gastricartery and plexus

39

NEUROANATOMYNerves of Small Intestine

Recurrent branch of left inferior phrenicartery and plexus to esophagus



Hepatic branch of anteriorvagal trunk (courses in lesseromentum, removed here)

Celiac branches of anteriorand posterior vagal trunks

Inferior phrenic arteries and plexuses


Hepatic plexus

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 pancreaticoduodenalarteries and plexuses

Superior mesentericartery and plexus

Middle colic artery and plexus (cut)

Right colic artery and plexus

Superior mesentericartery and plexus

Peritoneum (cut edge)

Mesenteric branches

Mesoappendix (containsappendicular artery andnerve plexus)

Ileocolic artery and plexus

40

NEUROANATOMY Nerves of Large Intestine

Anterior vagal trunk and hepatic branch


Celiac branches of anteriorand posterior vagal trunks

Right inferior phrenic artery and plexus

Right greater splanchnic nerve


Right lesser andleast splanchnic nerves


Superiormesentericganglion

Middle colicarteryand plexus

Inferiorpancreatico-duodenalarteriesand plexuses

Right colicarteryand plexus

Ileocolicarteryand plexus

Cecal andappendiculararteriesand plexuses

Right internaliliac arteryand plexus (cut)

Sacral sympathetic trunk

Right sacral plexus

Middle rectal artery and plexus

Right inferior hypogastric(pelvic) plexus

Vesical plexus

Rectal plexus

Urinary bladder

Marginal artery and plexus

Esophagus

Left inferior phrenicartery and plexus

Left gastric arteryand plexus

Left greatersplanchnic nerve

Left suprarenalplexus

Left lesser andleast splanchnicnerves

Left aorticorenalganglion

Left renal arteryand plexus

1st left lumbarsplanchnic nerve

Left lumbarsympathetic trunk


Left colic arteryand plexus

Inferiormesentericganglion, arteryand plexus

Sigmoidarteriesand plexuses

Superiorhypogastricplexus

Superiorrectalarteryand plexus

Right and lefthypogastricnerves

Rectosigmoidartery andplexus

Nerves from inferior hypogastric (pelvic)plexuses to sigmoid colon, descendingcolon and left colic (splenic) flexure

Pelvic splanchnic nerves

41

NEUROANATOMYNerves of Kidneys, Ureters and Urinary Bladder



Greater splanchnic nerve


Lesser splanchnic nerve


Least splanchnic nerve


Renal plexus and ganglion

2nd lumbar splanchnic nerve

Renal and upper ureteric branchesfrom 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

Hypogastric nerves

Sacral plexus

Pudendal nerve


Inferior hypogastric (pelvic) plexuswith periureteric loops andbranches to lower ureter

Rectal plexus

Vesical plexus

Prostatic plexus

42

NEUROANATOMY Nerves of Pelvic Viscera: Male


Posterior vagal trunkandCeliac 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,artery and plexus

Ureter and ureteric plexus


Superior rectal artery and plexus

Hypogastric nerves

Nerve from inferiorhypogastric plexusto sigmoid and descendingcolon (parasympathetic)

Sacral splanchnic nerves(sympathetic)

Inferior hypogastric(pelvic) plexus

Obturator nerveand artery

Ductus deferensand plexus

Vesical plexus

Rectal plexus

Prostatic plexus

Cavernous nervesof penis

Posterior scrotal nerves

Dorsal nerve of penis

Perineal nerve

Inferior anal (rectal) nerve

Levator ani muscle

Pudendal nerve

(Ischio-)coccygeusmuscle andsacrospinous ligament

Gluteus maximusmuscle and sacro -tuberous ligament

Piriformis muscle

Sacral plexus

Pelvic splanchnicnerves(parasympathetic)

S1 spinal nerve(anterior ramus)


Lumbosacral trunk

L5 spinal nerve (anterior ramus)

5th lumbar splanchnic nerve

Sympathetic trunk and ganglia


1st, 2nd, 3rd lumbar splanchnic nerves

GrayWhite

Ramicommunicantes

L1 spinal nerve(anterior ramus)

Left renal arteryand plexus

Diaphragm

GreaterLesserLeast

Splanchnicnerves

White and gray rami communicantes

T10 spinal nerve (anterior ramus)

43

NEUROANATOMYNerves of Pelvic Viscera: Female

Sympathetic trunk and L2 ganglion

White andgray ramicommunicantes

Lumbarsplanchnicnerves

Gray ramicommunicantes

L5 spinalnerve

Righthypogastricnerve (cut)

Right andleft sacralsympathetictrunks andganglia

Piriformismuscle

Sacralsplanchnicnerves(sympathetic)

Pudendalnerve

S5

S4

S3

S2

S1

Pelvicsplanchnicnerves(parasympathetic)

(Ischio-)coccygeus muscle

Rectal plexus

Rectum (retracted)

Uterus (retracted)

Uterovaginal plexus

Vesical plexus

Urinary bladder

Symphyseal surface of pubis

Ovary

Uterine (fallopian) tube

Inferior hypogastric (pelvic) plexus

Left hypogastric nerve

Right sympathetic trunk

Uterus

Right and lefthypogastric nerves

Sigmoidcolon

Externaliliac arteryand plexus

Internaliliac arteryand plexus

Commoniliac arteryand plexus



Ureter

Sacralpromontory

Ovarian arteryand plexus


Ureter

Commoniliac vesselsand plexus

Extraperitoneal(subserous)fascia

Abdominal aorta

Inferior vena cava

Peritoneum

44

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)

Articular branch

Flexor carpi radialis muscle

Palmaris longus muscle

Pronator teres muscle (ulnar head)

Flexor digitorum superficialis muscle(turned up)

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

Abductor pollicis brevis

Opponens pollicis

Superficial head offlexor pollicis brevis(deep head supplied byulnar nerve)

Thenarmuscles

1st and 2ndlumbrical muscles

Dorsal branches todorsum of middle anddistal phalanges

Medial

PosteriorLateral

Cords ofbrachialplexus

Medial cutaneousnerve of arm

Medial cutaneousnerve of forearm

Axillary nerve

Radial nerve

Ulnar nerve

Cutaneous innervation

Palmar view

Posterior (dorsal) view

Proper palmar digital nerves

Common palmar digital nerves

Communicating branchof median nerve withulnar nerve

45

NEUROANATOMYUlnar Nerve

Ulnar nerve (C7, 8, T1)(no branches above elbow)


Medial epicondyle

Articular branch(behind condyle)

Flexor digitorum profundusmuscle (medial part only;lateral part supplied byanterior interosseousbranch of median nerve)

Dorsal branch of ulnar nerve

Flexor carpi ulnaris muscle(drawn aside)

Palmar branch

Superficial branch

Deep branch

Palmaris brevis

Abductor digiti minimi

Flexor digiti minimi brevis

Opponens digiti minimi

Hypothenar muscles

Common palmar digital nerve

Palmar and dorsal interosseous muscles

Communicating branch of median nerve withulnar nerve

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

Adductor pollicis muscle

Posterior(dorsal) view

Flexor pollicis brevis muscle(deep head only; superficialhead and other thenar musclessupplied by median nerve)

Palmar view

Cutaneousinnervation

Anterior view Note: Only muscles innervated by ulnar nerve shown

46

NEUROANATOMY Radial Nerve in Arm and Nerves of Posterior Shoulder

Posterior view

Suprascapular nerve (C5, 6)

Dorsal scapular nerve (C5)

Supraspinatus muscle

Levator scapulaemuscle (suppliedalso by branchesfrom C3 and C4)

Rhomboidminor muscle

Rhomboidmajor muscle

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

Triceps brachii tendon

Medial epicondyle

Olecranon

Anconeus muscle

Extensor digitorum muscle

Extensor carpi ulnaris muscle

Extensor carpiradialis brevismuscle

Extensor carpi radialislongus muscle

Brachioradialis muscle

Brachialis muscle (lateralpart; remainder of musclesupplied by musculo-cutaneous nerve)

Lateral intermuscularseptum

Posterior cutaneousnerve of forearm

Inferior lateralcutaneous nerve of arm

Deltoid muscle

Teres minor muscle

Axillary nerve (C5, 6)

Superior lateralcutaneous nerve of arm

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


47

NEUROANATOMYRadial Nerve in Forearm

Posterior view

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

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- supinatorgroup of muscles

Extensor digitorum muscle andextensor digiti minimi muscle

Extensor indicis muscle

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 nerveSuperior lateralcutaneous nerveof arm

From radial nerve

Inferior lateralcutaneous nerveof arm

Superficial branch ofradial nerve and dorsaldigital branches

Posterior cutaneous nerve of arm

Posterior cutaneous nerve of forearm

Cutaneous innervation fromradial and axillary nerves

Dorsal digital nerves

48

NEUROANATOMY Sciatic Nerve and Posterior Cutaneous Nerve of Thigh

Posterior cutaneous nerve of thigh (S1, 2, 3)

Inferior cluneal nerves

Perineal branches

Tibial divisionof sciatic nerve

Long head (cut) of biceps femoris muscle

Adductor magnus muscle(also partially suppliedby obturator nerve)

Semitendinosus muscle

Semimembranosus muscle

Tibial nerve

Articular branch

Plantaris muscle

Medial suralcutaneous nerve

Gastrocnemius muscle

Sural nerve

Soleus muscle

Tibial nerve

Medial calcaneal branches

Medial and lateralplantar nerves

Greater sciatic foramen

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

Common fibular (peroneal) division of sciatic nerve

Short head of biceps femoris muscle


Long head (cut)of biceps femorismuscle

Common fibular(peroneal) nerve

Articular branch

Lateral suralcutaneous nerve

Suralcommunicatingbranch

Posteriorcutaneous nerveof thigh

From sciatic nerve

Lateral calcanealbranches

Lateral dorsalcutaneous nerve

Common fibular(peroneal) nerve via lateral suralcutaneous nerve

Medial suralcutaneous nerve

Superficial fibular(peroneal) nerve

Sural nerve

Tibial nervevia medialcalcanealbranches

49

NEUROANATOMYTibial Nerve

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

Medial suralcutaneous nerve (cut)

Articular branches

Plantaris muscle

Gastrocnemiusmuscle (cut)

Nerve to popliteus muscle

Popliteus muscle

Interosseous nerve of leg

Soleus muscle (cut andpartly retracted)

Flexor digitorumlongus muscle

Tibialis posterior muscle

Flexor hallucis longus muscle

Sural nerve (cut)

Lateral calcaneal branch

Medial calcaneal branch

Flexor retinaculum (cut)

Lateral dorsalcutaneous nerve

Common fibular (peroneal) nerve

Lateral sural cutaneous nerve (cut)

Medial calcaneal branches(S1, 2)

Medialplantar nerve(L4, 5)

Lateral plantar nerve(S1, 2)

Fromtibial nerve

Saphenous nerve(L3, 4)

Sural nerve (S1, 2) via lateral calcaneal and lateral dorsalcutaneous branches

Cutaneous innervation of sole

Flexor retinaculum(cut)

Tibialnerve

Medialcalcanealbranch

Medial plantarnerve

Flexor digitorumbrevis muscleand nerve

Abductor hallucismuscle and nerve

Flexor hallucisbrevis muscleand nerve

1st lumbricalmuscle andnerve

Commonplantardigital nerves

Properplantardigitalnerves

Lateral calcaneal branch of sural nerve

Lateral plantarnerve

Quadratus plantaemuscle and nerve

Nerve to abductor digiti minimi muscle

Abductor digitiminimi muscle

Deep branch to interosseousmuscles, 2nd, 3rd and 4thlumbrical musclesandAdductor hallucis muscle

Superficial branch to4th interosseousmuscleandFlexor digiti minimibrevis muscle

Common andProper plantardigital nerves

Note: Articular branches not shown

Articular branch

50

NEUROANATOMY Common Fibular (Peroneal) Nerve

Common fibular (peroneal) nerve (phantom)

Biceps femoris tendon

Common fibular (peroneal) nerve (L4, 5, S1, 2)

Head of fibula

Fibularis (peroneus) longus muscle (cut)

Superficial fibular(peroneal) nerve

Branches of lateralsural cutaneous nerve

Fibularis (peroneus) longus muscle

Fibularis (peroneus) brevis muscle

Medial dorsal cutaneous nerve

Intermediate dorsalcutaneous nerve

Inferior extensorretinaculum (partially cut)

Lateral dorsal cutaneous nerve(branch of sural nerve)

Dorsal digital nerves

Lateral sural cutaneous nerve (phantom)

Articular branches

Recurrent articular nerve

Extensor digitorum longus muscle (cut)

Deep fibular (peroneal) nerve

Tibialis anterior muscle


Extensor digitorumlongus muscle

Extensor hallucislongus muscle

Lateral sural cutaneous nerve

Superficial fibular (peroneal) nerve

Lateral branch ofdeep fibular (peroneal) nerve toExtensor hallucis brevisandExtensor digitorum brevismuscles

Medial branch ofdeep fibular(peroneal) nerve

Deepfibular(peroneal)nerve

Sural nervevia lateral dorsalcutaneous branch

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

Synaptic Transmission: Neuromuscular Junction . . . . . . . . . . . . . . . 56

Synaptic Transmission: Visceral Efferent Endings . . . . . . . . . . . . . . . 57

Synaptic Transmission: Inhibitory Mechanisms . . . . . . . . . . . . . . . . 58

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

Synaptic Transmission: 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

52

NEUROPHYSIOLOGY Organization of the Brain: Cerebrum

Central sulcus (Rolando)

Precentral gyrus

Postcentral gyrus

Postcentral sulcus

Superior parietal lobule

Inferior parietal lobule Supramarginal gyrus Angular gyrus

Parietooccipitalsulcus

Occipital pole

Calcarine sulcus

Inferior temporal gyrus

Middle temporal gyrus

Superior temporal gyrusTemporal pole

Lateral sulcus(Sylvius)

Frontal pole

Precentral sulcus

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 andmotor processing. In general, the frontal lobe processes motor,visual, speech, and personality modalities. The parietal lobeprocesses sensory information; the temporal lobe, auditory andmemory modalities; and the occipital lobe, vision. The cerebellum

coordinates smooth motor activities and processes muscle position.The brainstem (medulla, pons, midbrain) conveys motor and sensoryinformation and mediates important autonomic functions. The spinalcord receives sensory input from the body and conveys somatic andautonomic motor information to peripheral targets (muscles, viscera).

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53

NEUROPHYSIOLOGYOrganization of the Brain: Cell Types

Red:Blue:

Purple:Gray:

Motor neuronSensory neuronInterneuronGlial andneurilemmal cellsand myelin

Multipolar (pyramidal)cell of cerebralmotor cortex

Astrocyte

Multipolar somaticmotor cell of nucleiof cranial nn.

Multipolar cellof lower brain motor centers

Oligodendrocyte

Corticospinal(pyramidal) fiber

Axodendritic ending

Axosomatic ending

Axoaxonic ending

Multipolar somaticmotor cell ofanterior hornof spinal cord

Collateral

Renshaw interneuron(feedback)

Myelinated somatic motorfiber of spinal nerve

Myelin sheath

Motor endplate withSchwann cell cap

Striated(voluntary)muscle

Striated(somatic)muscle

Motorendplate

Interneurons

Interneuron

Astrocyte

Bipolar cell of cranial n.

Unipolar cell ofsensory ganglia ofcranial nn.

Satellite cells

Schwann cell

Free nerve endings(unmyelinated fibers)

Encapsulated ending

Specialized ending

Muscle spindle

Unipolar sensory cellof dorsal spinalroot ganglion

Satellite cells

Myelinated afferentfiber of spinal nerve

Myelin sheath

Schwann cells

Unmyelinated fibers

Free nerve endings

Encapsulated ending

Muscle spindle

Autonomic preganglionic(sympathetic or para-sympathetic) nerve fiber

Myelin sheath

Autonomic postganglionicneuron of sympathetic orparasympathetic ganglion

Satellite cells

Unmyelinated nerve fiber

Schwann cells

Beadedvaricositiesand endings onsmooth muscleand gland cells

Endings oncardiac muscleor nodal cells

Multipolar visceralmotor (autonomic)cell of spinal cord

Blood vessel

Note: Cerebellar cellsnot shown here

FIGURE 2.2 ORGANIZATION OF THE BRAIN: CELL TYPES•Neurons form the functional cellular units responsible for communication, and throughout the nervous system, they arecharacterized by their distinctive size and shapes (e.g., bipolar,unipolar, multipolar). Supporting cells include the neuroglia

(e.g., astrocytes, oligodendrocytes), satellite cells, and other spe-cialized cells that optimize neuronal function, provide mainte-nance functions, or protect the nervous system.

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54

NEUROPHYSIOLOGY Blood-Brain Barrier

Basementmembrane

Cellmembrane

Cytoplasm

Tightjunctionproteins

Astrocytefoot processes

Astrocyte

Capillaryendothelial

cell

Tightjunction

Capillarylumen

Redbloodcell

FIGURE 2.3 BLOOD-BRAIN BARRIER•The blood-brain barrier (BBB) is the cellular interface between theblood and the central nervous system (CNS; brain and spinal cord).It serves to maintain the interstitial fluid environment to ensureoptimal functionality of the neurons. This barrier consists of thecapillary endothelial cells with an elaborate network of tight junc-tions and astrocytic foot processes that abut the endothelium andits basement membrane. The movement of large molecules and

other substances (including many drugs) from the blood to theinterstitial space of the CNS is restricted by the BBB. CNS endothe-lial cells also exhibit a low level of pinocytotic activity across thecell, so specific carrier systems for the transport of essential sub-strates of energy and amino acid metabolism are characteristic ofthese cells. The astrocytes help transfer important metabolites fromthe blood to the neurons and also remove excess K� and neuro-transmitters from the interstitial fluid.

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55

NEUROPHYSIOLOGYSynaptic Transmission: Morphology of Synapses

FIGURE 2.4 MORPHOLOGY OF SYNAPSES•Neurons communicate with each other and with effector targets atspecialized regions called synapses. The top figure shows a typicalmotor neuron that receives numerous synaptic contacts on its cellbody and associated dendrites. Incoming axons lose their myelinsheaths, exhibit extensive branching, and terminate as synapticboutons (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 trans-mitters into the synaptic cleft, and then bind to receptors situatedin the postsynaptic membrane. This synaptic transmission results inexcitatory, inhibitory, or modulatory effects on the target cell.

Dendrite

Node Axon

Myelin sheathDendrites

Axolemma

Mitochondria

Postsynaptic cell

Enlarged sectionof bouton

Axon (axoplasm)

Glial process

Synaptic vesicles

Synaptic cleft

Presynaptic membrane (densely staining)

Postsynaptic membrane(densely staining)

Numerous boutons (synaptic knobs) of presynaptic neurons terminating on a motor neuron and its dendrites

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56

NEUROPHYSIOLOGY Synaptic Transmission: Neuromuscular Junction

Structure of Neuromuscular Junction

Active zone

Schwann cell process

Acetylcholinereceptor sites

Myofibrils

Synaptic cleft

Postsynapticmembrane

Junctional fold

Sarcoplasm

Acetylcholine receptor sites

Myelin sheath

Neurilemma

Axoplasm

Schwann cell

Mitochondria

Basement membrane

Nucleus of Schwann cell

Presynaptic membrane

Active zone

Synaptic vesicles

Synaptic trough

Basement membrane

Sarcolemma

Nucleus ofmuscle cell

FIGURE 2.5 STRUCTURE OF THE NEUROMUSCULAR JUNCTION•Motor axons that synapse on skeletal muscle form expanded termi-nals called neuromuscular junctions (motor endplates). The motoraxon loses its myelin sheath and expands into a Schwanncell–invested synaptic terminal that resides within a trough in themuscle fiber. Acetylcholine-containing synaptic vesicles accumu-late adjacent to the presynaptic membrane and, when appropri-

ately stimulated, release their neurotransmitter into the synapticcleft. The transmitter then binds to receptors that mediate depolar-ization of the muscle sarcolemma and initiate a muscle actionpotential. A single muscle fiber has only one neuromuscular junc-tion, but a motor axon can innervate multiple muscle fibers.

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57

NEUROPHYSIOLOGYSynaptic Transmission: Visceral Efferent Endings

FIGURE 2.6 VISCERAL EFFERENT ENDINGS•Neuronal efferent endings on smooth muscle (A) and glands (Band C) exhibit unique endings unlike the presynaptic and postsy-naptic terminals observed in neuronal and neuromuscular junc-tion synapses. Rather, neurotransmitter substances are releasedinto interstitial spaces (A and B) or into the bloodstream (C, neu-

rosecretion) from expanded nerve terminal endings. This arrange-ment allows for the stimulation of numerous target cells over awide area. Not all smooth muscle cells are innervated. They areconnected to adjacent cells by gap junctions and can thereforecontract together with the innervated cells.

Pituicyte processes

� � � � � � ��

Visceral Efferent Endings

A. Smooth muscle

Smooth muscle cells (cut)

Schwann cell cap enclosingnerve axons

Schwann cell cap

Smooth muscle cells

Varicosities

Terminal endings

B. Gland (submandibular)

Sympathetic terminalending

Varicosity

Schwanncell cap

Schwann cellcap enclosingnerve axons

Mucous cells

Varicosity

Parasympatheticterminal ending

Serous cells Schwann cellcap enclosingnerve axons

C. Neurosecretory(posterior pituitary)

Axon Axon

Fibroblast

Neurosecretoryvesicles

Collagen space

Basement membrane

Mast cell

Endothelium

Capillary

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58

NEUROPHYSIOLOGY

FIGURE 2.7 SYNAPTIC INHIBITORY MECHANISMS•Inhibitory synapses modulate neuronal activity. Illustrated here is presynaptic inhibition (left panel) and postsynaptic inhibition (rightpanel) at a motor neuron.

Synaptic Transmission: Inhibitory Mechanisms

A. Only E fires 90-mV spike in E terminal

B. Only I fires Long-lasting partial depolarization in E terminal

EPSP inmotor neuron

No response inmotor neuron

C. I fires before E Partial depolarization of E terminal reduces spike to 80 mV, thus releasing less transmitter substance

Smaller EPSP inmotor neuron

E(Excitatoryfiber)

E(Excitatoryfiber)

I(Inhibitoryfiber)

I(Inhibitoryfiber)

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Depolariza- tion of motor neuron less than if only E fires

©

59

NEUROPHYSIOLOGYSynaptic Transmission: Chemical Synaptic Transmission

FIGURE 2.8 CHEMICAL SYNAPTIC TRANSMISSION•Chemical synaptic transmission between neurons may be excita-tory or inhibitory. During excitation (left column), a net increase inthe inward flow of Na� compared with the outward flow of K�

results in a depolarizing potential change (excitatory postsynapticpotential [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 potentialaway from threshold (hyperpolarization) and decreases the proba-bility that the neuron will reach threshold (inhibitory postsynapticpotential [IPSP]) for an action potential.

�� Excitatory Inhibitory

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 postsy-naptic cell than K� moves out, due to great-er electrochemical gradient

Resultant net ionic current flow is in a direc-tion that tends to depolarize postsynaptic cell. If depolarization reaches firing threshold, an impulse is generated in postsynaptic cell

At inhibitory synapse, transmitter substance re-leased 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

Resultant ionic current flow is in direction that tends to hyperpolarize postsynaptic cell. This makes depolariza-tion by excitatory synapses more difficult—more depolari-zation is required to reach threshold

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©

60

NEUROPHYSIOLOGY Synaptic Transmission: Temporal and Spatial Summation

FIGURE 2.9 TEMPORAL AND SPATIAL SUMMATION •Neurons receive multiple excitatory and inhibitory inputs. Tempo-ral summation occurs when a series of subthreshold impulses inone excitatory fiber produces an action potential in the postsynap-tic cell (panel C). Spatial summation occurs when subthresholdimpulses from two or more different fibers trigger an action poten-

tial (panel D). Both temporal and spatial summation can be modu-lated by simultaneous inhibitory input (panel E). Inhibitory andexcitatory neurons use a wide variety of neurotransmitters, some ofwhich are summarized here.

Axon

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–70

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–70

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Temporal and Spatial Summationof Excitation and Inhibition

Excitatory fibers

Inhibitory fibers

Excitatory fibers

Inhibitory fibers

Excitatory fibers

Inhibitory fibers

Excitatory fibers

Inhibitory fibers

Excitatory fibers

Inhibitory fibers

Excitatory fibers

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

C. Temporal excitatory summation: a series of impulses in one excitatory fiber together produce a suprathreshold depolarization that triggers an action potential

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

D. Spatial excitatory summation: impulses in two excitatory fibers cause two synaptic depolarizations that together reach firing threshold triggering an action potential

Transmitter LocationAcetylcholine Neuromuscular junction, autonomic end-

ings and ganglia, CNSBiogenic amines

Norepinephrine Sympathetic endings, CNSDopamine CNSSerotonin CNS, GI tract

Amino acids�-Aminobutyric CNSacid (GABA)Glutamate CNS

PurinesAdenosine CNSAdenosine CNStriphosphate (ATP)

Transmitter LocationGas

Nitric oxide CNS, GI tractPeptides

�-Endorphins CNS, GI tractEnkephalins CNSAntidiuretic CNS (hypothalamus/posterior hormone pituitary)Pituitary-releasing CNS (hypothalamus/anterior hormones pituitary)Somatostatin CNS, GI tractNeuropeptide Y CNSVasoactive intestinal peptide CNS, GI tract

CHART 2.1 SUMMARY OF SOME NEUROTRANSMITTERS AND WHERE WITHIN THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM THEY ARE FOUND

CNS, Central nervous system; GI, gastrointestinal.

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61

NEUROPHYSIOLOGY

FIGURE 2.10 BRAIN VENTRICLES AND CSF COMPOSITION•CSF circulates through the four brain ventricles (two lateral ventri-cles and a third and fourth ventricle) and in the subarachnoidspace surrounding the brain and spinal cord. The electrolyte com-position of the CSF is regulated by the choroid plexus, which

secretes the CSF. Importantly, the CSF has a lower [HCO3�] than

plasma and therefore a lower pH. This allows small changes inblood PCO2 to cause changes in CSF pH, which in turn regulatesthe rate of respiration (see Chapter 5).

Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition

Left lateral phantom view

Right lateral ventricle

Left interventricularforamen (Monro)

3rd ventricle

Frontal (anterior) horn

Central part

Temporal (inferior) horn

Occipital (posterior) horn

Leftlateralventricle


4th ventricle

Left lateral recess

Central canal of spinal cord

Median aperture(foramen of Magendie)

Left lateral aperture(foramen of Luschka)

©

CSF Blood PlasmaNa� (mEq/L) 140–145 135–147K� (mEq/L) 3 3.5–5.0Cl− (mEq/L) 115–120 95–105HCO3

− (mEq/L) 20 22–28Glucose (mg/dL) 50–75 70–110Protein (g/dL) 0.05–0.07 6.0–7.8pH 7.3 7.35–7.45

CHART 2.2 CSF COMPOSITION

62

NEUROPHYSIOLOGY Cerebrospinal Fluid (CSF): Circulation of CSF

FIGURE 2.11 CIRCULATION OF CEREBROSPINAL FLUID•CSF circulates through the four brain ventricles (two lateral ventri-cles and a third and fourth ventricle) and in the subarachnoidspace surrounding the brain and spinal cord. Most of the CSF is

reabsorbed into the venous system through the arachnoid granula-tions and through the walls of the capillaries of the central nervoussystem and pia mater.


Arachnoid granulations


Subarachnoid space

Median aperture(foramen of Magendie)

Central canal of spinal cord

Subarachnoid space

Arachnoid

Arachnoid

Dura mater

Cistern of corpus callosum

Choroid plexus of lateralventricle (phantom)

Dura mater


Lateral aperture (foramen of Luschka)


Choroid plexus of 3rd ventricle

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63

NEUROPHYSIOLOGY

FIGURE 2.12 SPINAL CORD AND VENTRAL RAMI IN SITU•The spinal cord gives rise to 31 pairs of spinal nerves that distributesegmentally to the body. These nerves are organized into plexusesthat distribute to the neck (cervical plexus), upper limb (brachialplexus), and pelvis and lower limb (lumbosacral plexus). Motor

fibers of these spinal nerves innervate skeletal muscle, and sensoryfibers convey information back to the central nervous system fromthe skin, skeletal muscles, and joints.

Spinal Cord: Ventral Rami

Lumbar plexus

L5 vertebra

Sacral plexus

Sciatic nerve

Coccyx

Filamentsof spinalnerve roots(T7 and T8)

L1vertebra

Coccygeal nerve

Base of skull

C1 spinal nerve

C8 spinal nerve

T1 spinal nerve

1st rib

12th rib

Intercostalnerves

T12 spinalnerve

Conus medullaris

L1 spinal nerve

Cauda equina

S1 spinal nerve

Sacrum (cut away)

Termination ofdural sac

C1 vertebra (atlas)

Cervical plexus

Brachial plexus

Spinal dura mater

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64

NEUROPHYSIOLOGY

FIGURE 2.13 SPINAL MEMBRANES AND NERVE ROOTS•The spinal cord gives rise to 31 pairs of spinal nerves that distributesegmentally to the body. Motor fibers of these spinal nerves inner-vate skeletal muscle, and sensory fibers convey information backto the central nervous system from the skin, skeletal muscles, andjoints.

The spinal cord is ensheathed in three meningeal coverings: theouter, tough dura mater; the arachnoid mater; and the pia mater,which intimately ensheaths the cord itself. CSF bathes the cord andis found in the subarachnoid space.

Arachnoid mater

Posterior view

Membranes removed: anterior view(greatly magnified)

Gray and white ramicommunicantes

Gray matterWhite matter

Subarachnoid space

Pia mater overlying spinal cord

Filaments of dorsal root

Ventral root of spinal nerve

Dorsal root of spinal nerve


Ventral ramus of spinal nerve

Dorsal ramus of spinal nerve

Dura mater

Filaments of dorsal root

Dorsal root of spinal nerve

Filaments of ventral root

Spinal sensory (dorsalroot) ganglion

Dorsal ramus ofspinal nerve

Ventral ramus ofspinal nerve

Ventral root of spinal nerve

Spinal nerve

Spinal Cord: Membranes and Nerve Roots

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65

NEUROPHYSIOLOGYPeripheral Nervous System

FIGURE 2.14 PERIPHERAL NERVOUS SYSTEM•The peripheral nervous system (PNS) consists of all of the neuralelements outside of the CNS (brain and spinal cord) and providesthe connections between the CNS and all other body organ sys-tems. The PNS consists of somatic and autonomic components. Thesomatic 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 bothmotor and sensory axons. Cell bodies of the motor neurons arefound in the anterior horn gray matter, whereas the cell bodies ofsensory neurons are located in the dorsal root ganglia.

Sensory neuron cell body

Dorsal root ganglion

Dorsal root

Posterior horn

Anterior horn

Motor neuron cell body

Motor neuron

Neuromuscularjunction

Muscle

Skin

Sensory neuron

Ventral root

Peripheral nerve

Axon

Myelin sheath

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with

66

NEUROPHYSIOLOGY Autonomic Nervous System: Schema

FIGURE 2.15 AUTONOMIC NERVOUS SYSTEM: SCHEMA•The autonomic nervous system is composed of two divisions: theparasympathetic division derived from four of the cranial nerves (CN III, VII, IX, and X) and the S2-S4 sacral spinal cord levels, and thesympathetic division associated with the thoracic and upper lumbarspinal cord levels (T1-L2). The autonomic nervous system is a two-neuron chain, with the preganglionic neuron arising from the centralnervous system and synapsing on a postganglionic neuron located in

a peripheral autonomic ganglion. Postganglionic axons of the auto-nomic nervous system innervate smooth muscle, cardiac muscle, andglands. Basically, the sympathetic division mobilizes our body (“fightor flight”) while the parasympathetic division regulates digestive andhomeostatic functions. Normally, both divisions work in concert toregulate visceral activity (respiration, cardiovascular function, diges-tion, and associated glandular activity).

Intracranial vesselsCiliary ganglion

EyePterygopalatine ganglion

Lacrimal glandsOtic ganglion

Parotid glands

Sublingual andsubmandibular glands

Peripheral cranialand facial vessels

LarynxTracheaBronchiLungs

Heart

Stomach

Pancreas

Suprarenal glands

Kidneys

Intestines

Descending colon

Sigmoid colon

Urinary bladder

Prostate

External genitalia

Rectum


Pulmonary plexus

Cardiac plexus

Celiac ganglion


Superior mesenteric

ganglion

Inferior mesenteric

ganglion

Superior hypogastric

plexus

Inferior

hypogastric

plexus

Lumbarsplanchnic

nerves

Splanchnicnerves

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Postsynaptic

Antidromic

conduction

Presynaptic

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Sympathetic

fibers

Parasympathetic

fibers


Facial nerve (VII)


Medulla oblongata

Vagus nerve (X)

Sweatgland

Peripheralblood vessel

Arrector (smooth) muscle of hair follicle

Note: Above three structures are shown at only one level but occur at all levels

Note: Blue-shaded areas indicate zones of parasympathetic outflow from CNS

Coccygeal

S5

S4S3

S2

S1

L5

L4

L3

L2

L1

T12

T9

T8

T7

T6

T5T4

T3

T2

T1

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C7C6

C5

C4

C3

C2

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T11

T10

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nic

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tes

Liver

Gallbladder

Bile ducts

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67

NEUROPHYSIOLOGYAutonomic Nervous System: Cholinergic and Adrenergic Synapses

FIGURE 2.16 CHOLINERGIC AND ADRENERGIC SYNAPSES: SCHEMA•The autonomic nervous system (ANS) is a two-neuron chain, withthe preganglionic neuron arising from the central nervous systemand synapsing on a postganglionic neuron located in a peripheralautonomic ganglion. Acetylcholine is the neurotransmitter in boththe sympathetic and parasympathetic ganglia. The parasympatheticdivision of the ANS releases acetylcholine at its postganglionicsynapses and is characterized as having cholinergic (C) effects,whereas the sympathetic division releases predominantly noradren-

aline (norepinephrine) at its postganglionic synapses, causingadrenergic (A) effects (except on sweat glands, where acetylcholineis released). Although acetylcholine and noradrenaline are thechief transmitter substances, other neuroactive peptides often arecolocalized with them and include such substances as gamma-aminobutyric acid (GABA), substance P, enkephalins, histamine,glutamic acid, neuropeptide Y, and others.

Somatic fibers

Antidromic conduction

Medullaoblongata

Thoracicpart ofspinal cord

Sacralpart ofspinal cord

Upperlumbarpart ofspinal cord(L1-2 [3])

Cervicalsympatheticganglia

Gray ramuscommunicans

Glossopharyngeal

nerve (IX)

Internal carotid nerve

Vagus nerve (X)

White ramuscommunicans

Celiacganglion

Superiormesentericganglion

Inferiormesenteric ganglion


C Cholinergic synapses

A Adrenergic synapses

Parotidgland

LarynxTracheaBronchiLungs

Heart

Striated muscle

Sweat glands

Hair follicles

Peripheral arteries

Visceralarteries

Gastrointestinaltract

Urinary bladder

UrethraProstate

Presynaptic

Postsynaptic

Presynaptic

Postsynaptic

Sympatheticfibers

Parasympatheticfibers

Suprarenalgland

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68

NEUROPHYSIOLOGY Hypothalamus

FIGURE 2.17 SCHEMATIC RECONSTRUCTION OF THE HYPOTHALAMUS•The hypothalamus, part of the diencephalon, controls a number ofimportant homeostatic systems within the body, including tempera-ture regulation, food intake, water intake, many of the endocrinesystems (see Chapter 8), motivation, and emotional behavior. Itreceives 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 heartrate), and the optic system, and it integrates these inputs for regula-tion of the functions listed.

Anteriorlobe ofpituitary

Optic chiasm

Optic (II)nerve

Olfactorytract

Medialpreopticnucleus

Lateralpreopticnucleus

Lateralventricle

Medial forebrainbundle

Anteriorcommissure

Septumpellucidum

Fornix

Corpus callosum

Fromhippocampalformation


Thalamus

Lateralhypothalamic area

Paraventricular nucleus

Anterior hypothalamic area

Dorsal hypothalamic area

Dorsomedial nucleus

Mamillothalamic tract

Posterior area

Periventricularnucleus

Nucleusintercalatus

Fornix

Ventromedialnucleus

Tuberohypophyseal tract

Supraoptic nucleus

Supraopticohypophysealtract

Posterior lobe of pituitary

Oculomotor (III) nerve

Mamillarycomplex

Red nucleusCerebralpeduncle

Dorsallongitudinalfasciculus

Descendinghypothalamicconnections

Pons

Reticularformation

Hypothalamic Area Major Functions*Preoptic and anterior Heat loss center: cutaneous vasodilation and sweatingPosterior Heat conservation center: cutaneous vasoconstriction and shiveringLateral Feeding center: eating behaviorVentromedial Satiety center: inhibits eating behaviorSupraoptic (subfornical organ and organum vasculosum) ADH and oxytocin secretion (sensation of thirst)Paraventricular ADH and oxytocin secretionPeriventricular Releasing hormones for the anterior pituitary

CHART 2.3 MAJOR FUNCTIONS OF THE HYPOTHALAMUS

*Stimulation of the center causes the responses listed.

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69

NEUROPHYSIOLOGYLimbic System

FIGURE 2.18 HIPPOCAMPUS AND FORNIX•The limbic system includes the hypothalamus and a collection ofinterconnected structures in the telencephalon (cingulate, parahip-pocampal, and subcallosal gyri), as well as the amygdala and hip-

pocampal formation. The limbic system functions in linking emo-tion and motivation (amygdala), learning and memory (hippocam-pal formation), and sexual behavior (hypothalamus).



Columns of fornix

Body of fornix

Thalamus

Uncus

Crura of fornix


Hippocampus

Commissure of fornix


Lateral ventricle

Amygdaloid bodies

Mamillarybodies

Columnsof fornix

Body of fornix

Commissureof fornix

Crura of fornix

Hippocampuswith fimbria ©

70

NEUROPHYSIOLOGY The Cerebral Cortex

FIGURE 2.19 CEREBRAL CORTEX: LOCALIZATION OF FUNCTION AND ASSOCIATION PATHWAYS•The cerebral cortex is organized into functional regions. In addi-tion to specific areas devoted to sensory and motor functions, thereare areas that integrate information from multiple sources. Thecerebral cortex participates in advanced intellectual functions,

including aspects of memory storage and recall, language, highercognitive functions, conscious perception, sensory integration, andplanning/execution of complex motor activity. General corticalareas associated with these functions are illustrated.

Motor controlof speech

Prefrontal;inhibitory controlof behavior;higherintelligence

Premotor; orientation;eye and headmovements

MotorMs IMs II

SensorySm ISm II

MotorMs IMs II

SensorySm ISm III ?

Sensoryanalysis

Visual I

Visual II

Visual III

Language;reading; speech

Auditory I

Auditory II

Olfactory

Cingulate gyrus(emotional behavior)and cingulum

Prefrontal;inhibitory controlof behavior;higherintelligence

Premotor

Visual I

Visual II

Visual III

Corpus callosum

Hippocampal commissure

Anterior commissure

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71

NEUROPHYSIOLOGY

FIGURE 2.20 CORTICOSPINAL TRACTS•The corticospinal, or pyramidal, tract is the major motor tract thatcontrols voluntary movement of the skeletal muscles, especiallyskilled movements of distal muscles of the limbs. All structuresfrom the cerebral cortex to the anterior horn cells in the spinal

cord constitute the upper portion of the system (upper motor neu-ron). The anterior horn cells and their associated axons constitutethe lower portion of the system (lower motor neuron).

Descending Motor Pathways

Basispedunculi

Hip

Tru

nk

Sh

ou

lde

rE

lbo

wW

rist

Finge

rs

Thumb

Neck

Brow

Eyelid

Nares

Lips

Tongue

Larynx

Knee

Ankle

Toes

Basispontis

Pyramids

Midbrain

Internalcapsule

Motorcortex

Pons

Medulla

Medulla

Spinalcord

Above mid-thoraciclevel

Below mid-thoraciclevel

Decussationof pyramids

Anterior corticospinal tract

Lateral corticospinal tract

Motorendplate

Motorendplate

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

Synapse occurs at spinal level: Lateral corticospinal fibers synapse on ipsilateral anterior horn cells; anterior corticospinal fibers synapse on contralateral anterior horn cells

Lateral aspect of cerebral cortex to show topographic projection of motor centers on precentral gyrus

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72

NEUROPHYSIOLOGY

FIGURE 2.21 CEREBELLAR AFFERENT PATHWAYS•The cerebellum plays an important role in coordinating movement. Itreceives sensory information and then influences descending motorpathways to produce fine, smooth, and coordinated motion. Thecerebellum is divided into three general areas: archicerebellum (alsocalled vestibulocerebellum) paleocerebellum (also called spinocere-bellum) and the neocerebellum (also called the cerebrocerebellum).The archicerebellum is primarily involved in controlling posture andbalance, as well as the movement of the head and eyes. It receivesafferent signals from the vestibular apparatus and then sends efferentfibers to the appropriate descending motor pathways. The paleocere-

bellum primarily controls movement of the proximal portions of thelimbs. It receives sensory information on limb position and muscletone and then modifies and coordinates these movements throughefferent pathways to the appropriate descending motor pathways. Theneocerebellum is the largest portion of the cerebellum, and it coordi-nates the movement of the distal portions of the limbs. It receivesinput from the cerebral cortex and thus helps in the planning ofmotor activity (e.g., seeing a pencil and then planning and executingthe movement of the arm and hand to pick it up).

Schema oftheoretical“unfolding”of cerebellarsurface inderivation ofabove diagram

Cortical input

Nucleusreticularistegmentipontis

Pontine nuclei(contralateral)

Spinal input

Inferior olive

Upper partof medullaoblongata

Spinal input

Vestibular nerveand ganglion

Lower partof medulla oblongata

Cortical input

Lateral reticularnucleus

Spinal input

Cervical part of spinal cord

Motor interneuron

Rostralspinocerebellartract

Spinal border cells

Motor interneuron

Lumbar partof spinal cord

Clarke’s column

Ventral spino-cerebellar tract



To contralateral cerebellar cortex

Primary fissure

LegArm

Face

To nodule and flocculus

Inferior cerebellar peduncleVestibularnuclei

Reticulocerebellartract

Cuneocerebellartract

Gracile nucleus

Main cuneatenucleus (relayfor cutaneousinformation)

External cuneate nucleus(relay for proprioceptive information)

From skin (touchand pressure)

From muscle (spindlesand Golgi tendon organs)

From skin anddeep tissues(pain and Golgitendon organs)

From skin (touchand pressure)and from muscle(spindles andGolgi tendonorgans)

Dorsal spinocerebellar tract

Functional Subdivisions of Cerebellum

Neocerebellum(pontocerebellum)

Middle vermisHemisphere

Paleocerebellum(spinocerebellum)

UvulaPyramidVermis

Archi-cerebellum(vestibulo-cerebellum)

LingulaFlocculusNodule

2nd spinal projectionarea (gracilelobule)

Leg zoneArm zoneFace zone

Hemisphere Vermis

Lateralpart

Inter-mediate part Anterior lobe

Primaryfissure

Middle(posterior)lobe

Posterolateralfissure

Flocculo-nodular lobe

Cerebellum: Afferent Pathways

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73

NEUROPHYSIOLOGY

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 involvedin controlling posture and balance and movement of the head andeyes. It sends efferent fibers to the appropriate descending motorpathways. The paleocerebellum primarily controls movement of

the proximal portions of the limbs. It modifies and coordinatesthese movements through efferent pathways to the appropriatedescending motor pathways. The neocerebellum coordinates themovement of the distal portions of the limbs. It helps in the plan-ning of motor activity (e.g., seeing a pencil and then planning andexecuting the movement of the arm and hand to pick it up).

Cerebellum: Efferent Pathways

SectionA–Bviewedfrombelow

SectionB–Cviewedfrom above

Planes ofsection:red arrowsindicatedirectionof viewPontomedullary reticular formation

Medulla oblongata

Lateral reticular nucleus

Inferior olive

Inferior cerebellarpeduncle

Vestibularnuclei

Cerebellarcortex

Dentate nucleus

Emboliform nucleus

Globose nuclei

Fastigial nucleus

Red nucleus

Mesencephalic reticular formation

Ventral anterior andventral lateral nuclei of thalamus

Inhibitoryendings ofPurkinjecells

Excitatoryendings

Motor andpremotor cerebralcortex

Internal capsule

Cerebral peduncle

Decussation of superiorcerebellar peduncles

Descending fibers fromsuperior cerebellarpeduncles

Hook bundle of Russell

A

B

C

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74

NEUROPHYSIOLOGY

FIGURE 2.23 SKIN AND CUTANEOUS RECEPTORS•Cutaneous receptors respond to touch (mechanoreceptors), pain(nociceptors), and temperature (thermoreceptors). Several differenttypes of receptors are present in skin. Meissner’s corpuscles havesmall receptive fields and respond best to stimuli that are appliedat low frequency (i.e., flutter). The pacinian corpuscles are locatedin 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 andpressure (i.e., indenting the skin). Ruffini’s corpuscles have largereceptive fields, and they also respond to touch and pressure. Freenerve endings respond to pain and temperature.

Subcutaneousartery and vein

Cutaneousnerve

Motor(autonomic)

nerve

Skin ligaments(retinacula cutis)

Elastic fibers

Sensory nerves

Vein

Artery

Paciniancorpuscle

Papilla of hair follicle

Hair matrix

Sweat gland

Hair cuticle

Ha

ir f

olli

cle

Connectivetissue layer

Glassymembrane

External sheath

Internal sheath

Cuticle

Sebaceous gland

Arrector muscle of hair

Melanocyte

Hair shaft

Free nerve endings Meissner’s corpuscle

Pore of sweat gland

Stratum corneumStratumlucidum Stratum

granulosum

Stratumspinosum

Stratumbasale

Dermalpapilla(of papillarylayer)

Reticularlayer

Ep

ide

rmis

De

rmis

Su

bc

uta

ne

ou

s tissue

Cross section

Detail of free nerve ending

Detail of Merkel’s disc

Mitochondria

Basalepithelialcells

Cytoplasmicprotrusion

Lobulatednucleus

Granulatedvesicles

Expandedaxon terminal

Schwanncell

Desmosomes

Merkelcell

Schwann cells

Axon

Basement membrane

Axon terminal

Mitochondrion

Schwann cell

Cutaneous Sensory Receptors

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75

NEUROPHYSIOLOGY

FIGURE 2.24 PACINIAN CORPUSCLE•Pacinian corpuscles are mechanoreceptors that transduce mechani-cal forces (displacement, pressure, vibration) into action potentialsthat are conveyed centrally by afferent nerve fibers. As the vis-coelastic lamellae are displaced, the unmyelinated axon terminalmembrane’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 amechanical force while the concentric lamellae dissipate slowchanges in pressure. In the absence of the capsule, the generatorpotential decays slowly and yields only a single action potential.

Cutaneous Receptors: Pacinian Corpuscle

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�

Pressure Na+

A. Sharp “on and off” changes in pressure at start and end of pulse applied to lamellated capsule are transmitted to central axon and provoke generator potentials, which in turn may trigger action potentials; there is no response to a slow change in pressure gradient. Pressure at central core 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)

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

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

Pacinian Corpuscleas Pressure Transducer

1st node

Myelin sheath

Lamellated capsule

Central core

Unmyelinated axon terminal

To amplifierPressure

Generator potential

Action potential

To amplifier

Pressure

Generator potential

Action potential

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NEUROPHYSIOLOGY

FIGURE 2.25 PROPRIOCEPTION: SPINAL EFFECTOR MECHANISM•Position sense or proprioception involves input from cutaneousmechanoreceptors, Golgi tendon organs, and muscle spindles(middle figure of upper panel). Both monosynaptic reflex pathways(middle figure of upper panel) and polysynaptic pathways involv-ing several spinal cord segments (top and bottom figures of upper

panel) initiate muscle contraction reflexes. The lower panel showsthe somatotopic distribution of the motor neuron cell bodies in theventral horn of the spinal cord that innervate limb muscles (flexorand extensor muscles of upper and lower limbs).

Proprioception and Reflex Pathways: I

In cervicalenlargement ofspinal cord

In lumbarenlargementof spinal cord


Dorsal horn interneuron

Flexor reflex interneuron

Dorsal horn interneuron

Dorsal horninterneuron

Fromcutaneousreceptor

Frommusclespindle

Dorsal rootganglion

Ventral root

� motor axon

From motor neuron

To motor neuron

To motor neuron

Schematic representation of motor neurons

Spinal Effector Mechanisms

Flex ors

Extensors

Fle xors

Exte nsors

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NEUROPHYSIOLOGY

Detail ofmuscle spindle

Efferent fibers

Afferent fibers

A� fibers fromGolgi-typeendings

A� fibers frompaciniform corpusclesand Ruffini terminals

A� and C fibersfrom free nerveendings

Extrafusalmuscle fiber

Intrafusalmuscle fibers

Sheath

Lymph space

Nuclear bag fiber

Nuclear chain fiber

Ib (A�) fibers from Golgi tendonorgans (proprioception)

Alpha motor neuron to extrafusalmuscle fiber end plates

Gamma motor neuron to intrafusalmuscle fiber and plates

II (A�) fiber from flower spray endings

Ia (A�) fiber from annulospiral endings

IV (unmyelinated) fibers from freenerve endings (pain)

III (A�) fibers from free nerve endingsand from some specialized endings(pain and some pressure)

II (A�) fibers from flower sprayendings (proprioception);from paciniform corpuscles (pressure)and pacinian corpuscles (pressure)

Ia (A�) fibers from annulospiralendings (proprioception)

Gamma motor neurons to intrafusalstriated muscle end plates

Alpha motor neurons to extrafusalstriated muscle end plates

Proprioception and Reflex Pathways: II

FIGURE 2.26 MUSCLE AND JOINT RECEPTORS•Muscle spindles and Golgi tendon organs send afferent signals tothe brain to convey the position of limbs and help coordinate mus-cle movement. Muscle spindles convey information on muscle ten-sion and contraction (dynamic forces) and muscle length (staticforces). 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 bagand nuclear chain fibers. If the muscle tension is too great (e.g.,overstretching of muscle or too heavy a load), activation of theGolgi tendon organ causes a reflex relaxation of the muscle.

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NEUROPHYSIOLOGY

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 Band C).

Alpha andgammaactivationfrom brain

Alpha activationfrom brain

Inhibitory interneuron

Golgitendonorgan

Golgitendonorgan

Golgitendonorgan

Extrafusal muscle fiber

Intrafusal muscle fiber

Alpha motor neurons ��

Gamma motor neurons

Ib fibers

Ia fibers ��




Gamma motor neurons

Ib fibers ��

Ia fibers




Gamma motor neurons ��

Ib fibers ��

Ia fibers ��

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

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

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

Proprioception and Reflex Pathways: III

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NEUROPHYSIOLOGYProprioception and Reflex Pathways: IV

FIGURE 2.28 SPINAL REFLEX PATHWAYS•Summary of the spinal reflex pathways.

Nociceptive fibers

Ipsilateralflexion

Inhibitory synapse

Excitatory synapse

Excitatory synapse

Inhibitory synapse

To extensors

To flexors

To extensors

To flexors

A. Afferent inhibitionB. Stretch reflex

(reciprocal inhibition)

C. Recurrent inhibition

E. Flexor withdrawal reflex

D. Tendon organ reflex

Contralateralextension

From extensor spindlereceptor (Ia, II fibers)

From flexor spindle(Ia, II fibers)

Axoaxonic presynapticinhibitory synapse

To extensors

From extensor spindlereceptor (Ia, II fibers)

Axosomatic oraxodendriticinhibitorysynapse

Excitatorysynapse

To extensors

To flexors

To extensors

To flexors

Renshaw cells

Collaterals

To synergisticmuscles

From extensor tendonorgan (Ib fibers)

Inhibitory synapse

Excitatory synapse

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NEUROPHYSIOLOGY

FIGURE 2.29 SOMESTHETIC SYSTEM OF THE BODY•Pain, temperature, and pressure sensations below the head ulti-mately are conveyed to the primary somatosensory cortex (post-central gyrus) by the anterolateral system (spinothalamic and spin-oreticular tracts). The fasciculus gracilis and cuneatus of the spinallemniscal system convey proprioceptive, vibratory, and tactile sen-

sations to the thalamus (ventral posterolateral nucleus), whereasthe lateral cervical system mediates some touch, vibratory, andproprioceptive sensations (blue and purple lines show these dualpathways). Ultimately, these fibers ascend as parallel pathways tothe thalamus, synapse, and ascend to the cortex.

Cerebral cortex:postcentral gyrus

Posterior limb ofinternal capsule

Ventral posterolateral(VPL) nucleus ofthalamus

Medial lemniscus

Gracile nucleus

Cuneate nucleus

Fasciculus gracilis

Fasciculus cuneatus

Dorsal (posterior) spinalroot ganglion

Proprioception,position Large

myelinatedfibers

Touch,pressure,vibration

Pain,temperature

Smallmyelinatedand unmyelin-ated fibers

Lateral cervical nucleus

Spinocervical tract

Lumbar partof spinal cord

Ventral (anterior)spinothalamic tract:touch, pressure

Lateralspinothalamic tract:pain, temperature

Cervical partof spinal cord

Reticular formation

Lower part ofmedulla oblongata

Spinothalamic tract

Mesencephalon(cerebral peduncles)

Sensory Pathways: I

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NEUROPHYSIOLOGY

FIGURE 2.30 SOMESTHETIC SYSTEM OF THE HEAD•Nerve cells bodies for touch, pressure, pain, and temperature inthe head are in the trigeminal (semilunar) ganglion of the trigemi-nal (CN V) nerve (blue and red lines in figure). Neuronal cell bod-ies mediating proprioception reside in the mesencephalic nucleus

of CN V (purple fibers). Most relay neurons project to the con-tralateral VPM nucleus of the thalamus and thence to the postcen-tral gyrus of the cerebral cortex, where they are somatotopicallyrepresented.

Sensory Pathways: II

Facial (VII) n.

Vagus (X) n.

Dorsolateral fasciculus (of Lissauer)

Substantia gelatinosa (Iamina II)

Cervicalpart ofspinalcord

Spinaltrigeminalnucleus

Spinaltrigeminaltract

Medullaryreticularformation

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 rootandMotor root of mandibular n.

Pontinereticularformation

Ventraltrigeminallemniscus

Midbrain(cerebralpeduncles)

Cerebral cortex:postcentral gyrus

Ventral posteromedial (VPM)nucleus of thalamus

Internal capsule

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NEUROPHYSIOLOGY

FIGURE 2.31 DERMATOMES•Sensory information below the head is localized to specific areasof the body, which reflect the distribution of peripheral sensoryfibers that convey sensations to the spinal cord through the dorsalroots (sensory nerve cell bodies reside in the corresponding dorsalroot ganglion). The area of skin subserved by afferent fibers of one

dorsal root is called a dermatome. This figure shows the der-matome segments and lists key dermatome levels used by clini-cians. Variability and overlap occur, so all dermatome segmentsare only approximations.

Levels of principal dermatomes

C5C5, 6, 7C8, T1C6C6, 7, 8C8T4

ClaviclesLateral parts of upper limbsMedial sides of upper limbsThumbHandRing and little fingersLevel of nipples

T10T12L1, 2, 3, 4 L4, 5, S1L4S1, 2, L5S1S2, 3, 4

Level of umbilicusInguinal or groin regionsAnterior and inner surfaces of lower limbsFootMedial side of great toePosterior and outer surfaces of lower limbsLateral margin of foot and little toePerineum

C7C8

C2

C3

C4C5C6

T1T2T3T4T5T6T7T8T9T10T11T12

T1T2T3T4T5T6T7T8T9

T10

T11

T12

L1L2L3L4L5

S1

S1

S2

S2

S2S1

L4L4

L5L5

S1

L4

S1

S3

C8

C8

C5

C6 C6

C2

C3C4

C5

T1

C8 C7

C7

C7

C6

S4

S5

L5

L1

L1

L2S2, 3

L3

L4

L5

L2

L3

Schematic demarcation of dermatomes shown as distinct segments. There is actually considerable overlap between any two adjacent dermatomes

Sensory Pathways: III

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NEUROPHYSIOLOGY

FIGURE 2.32 VISUAL RECEPTORS•The rods and cones of the retina transduce light into electrical sig-nals. As illustrated for the rod, light is absorbed by rhodopsin, andthrough the second messenger cGMP (not shown), Na� channelsin 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 receptorresponses, in which the response to a stimulus results in a depolar-ization of the receptor cell membrane.

Visual System: Receptors

Photonsof light

Lumirhodopsin

Metarhodopsin

Retinene+

Opsin

Vitamin A

Rhodopsin

Metabolicenergy

Retinene+

Opsin

Vitamin A

Circulation

A. Eyeball

Suspensoryligament

IrisLens

Cornea

Ciliarybody

Retina

Choroid

Sclera

FoveaOptic nerve

Oraserrata

Anteriorchamber

Posteriorchamber

containingaqueous humor

Vitreous humor

Inner limitingmembrane

Ganglion cell

Amacrine cell

Bipolar cell

Horizontal cell

Rod

Cone

Pigment cellsof choroid

Müller cell(supporting glialcell)

Axons at surfaceof retina passingvia optic nerve,chiasm, and tractto lateralgeniculate body

B. Sectionthrough retina

Synapticendingfullypolarized

Synaptic bar

Nucleus

Centriole(basal body)

Na+

permeabilitydecreased

Synapticendingdepolarized

Currentflow

Na+

permeabilityincreased

C. Rod in dark D. Rod in light

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NEUROPHYSIOLOGY

FIGURE 2.33 RETINOGENICULOSTRIATE VISUAL PATHWAY•The retina has two types of photoreceptors: cones that mediatecolor vision and rods that mediate light perception but with lowacuity. The greatest acuity is found in the region of the macula ofthe retina, where only cones are found (upper left panel). Visualsignals are conveyed by the ganglion cells whose axons course inthe optic nerves. Visual signals from the nasal retina cross in the

optic chiasm while information from the temporal retina remains inthe ipsilateral optic tract. Fibers synapse in the lateral geniculatenucleus (visual field is topographically represented here andinverted), and signals are conveyed to the visual cortex on themedial surface of the occipital lobe.

Visual System: Visual Pathway

Overlappingvisual fields

Projection onleft retina

Projection onright retina

Centraldarkercirclerepresentsmacularzone

Lightestshadesrepresentmonocularfields

Eachquadranta differentcolor

Calcarinefissure

Projectionon leftoccipital lobe

Projectionon rightoccipital lobe

Projection on leftdorsal lateralgeniculate nucleus

Projection on rightdorsal lateralgeniculate nucleus

Lateralgeniculatebodies

Choroid Choroid

Periphery

Structure of retina (schematic):

ABCGHPR

GG

A

HH

R R C C

PP

A

B B

Amacrine cellsBipolar cellsConesGanglion cellsHorizontal cellsPigment cellsRods

Macula

Optic tracts

Optic chiasm

Optic(II) nerves

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NEUROPHYSIOLOGY

FIGURE 2.34 COCHLEAR RECEPTORS•The cochlea transduces sound into electrical signals. This isaccomplished by the hair cells, which depolarize in response tovibration of the basilar membrane. The basilar membrane moves in

response to pressure changes imparted on the oval window of thecochlea in response to vibrations of the tympanic membrane.

Auditory System: Cochlea

Utricle

Saccule

Semicircularcanals

Cochlear nerve

Oval window and stapesRound window

A. Membranouslabyrinth withinbony labyrinth(path of soundwaves)

B. Sectionthrough turnof cochlea

Spiral ganglion

Afferentnerve fibers

Efferentnerve fibers

Scala vestibuliCochlear duct(scala media)

Scala tympani

Scala vestibuli(perilymph); weakly positive +80 mV

Scala tympani(perilymph); 0 mV

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

As basilar membrane moves up, hairs are deflected outward, causingdepolarization of hair cells and increased firing of afferent nerve fibers

C. Spiral organof Corti Hair cells

Inner OuterTectorial membrane

Stereocilia

Basilar membrane

Supporting cells

Afferent nerve fibers

Efferent nerve fibers

Spiral laminaSpiral ganglion

Rodsandtunnelof Corti

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NEUROPHYSIOLOGY

FIGURE 2.35 AUDITORY PATHWAYS•The cochlea transduces sound into electrical signals. Axons conveythese signals to the dorsal and ventral cochlear nuclei, where it istonotopically organized. Following a series of integrated relaypathways, the ascending pathway projects to the thalamus (medial

geniculate bodies) and then the acoustic cortex in the transversegyrus of the temporal lobe, where information is tonotopically rep-resented (low, middle, and high tones).

Auditory System: Pathways

Brachium ofinferiorcolliculus

Inferiorcolliculus

Midbrain

Laterallemnisci

Medullaoblongata

Nuclei oflaterallemnisci

Acoustic area oftemporal lobe cortex


Dorsal cochlear nucleus

Inferior cerebellar peduncle

Ventral cochlear nucleus

Cochlear division ofvestibulocochlear nerve

Spiral ganglion

Dorsalacoustic stria

Reticular formation

Trapezoid body

Intermediate acoustic stria

Correspondencebetween cochleaand acoustic areaof cortex:

Low tonesMiddle tonesHigh tones

Superior olivary complex

Hair cells

Inner Outer

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NEUROPHYSIOLOGY

FIGURE 2.36 VESTIBULAR RECEPTORS•The vestibular apparatus detects movement of the head in the formof linear and angular acceleration. This information is important forthe control of eye movements so that the retina can be providedwith a stable visual image. It is also important for the control ofposture. The utricle and saccule respond to linear acceleration,

such as the pull of gravity. The three semicircular canals arealigned so that the angular movement of the head can be sensed inall planes. The sensory hair cells are located in the maculae of theutricle and saccule and in the cristae within each ampullae.

Vestibular System: Receptors

Vestibular ganglion

Vestibularand cochleardivisions ofvestibulocochlear n.

Maculae

Saccule

Utricle

Cochlear duct(scala media)

B. Section of crista

Opposite wallof ampulla

Gelatinous cupula

Hair tufts

Hair cells

Nerve fibers

Basementmembrane

Superior semi-circular canal

Cristae withinampullae

Horizontal semi-circular canal

Posterior semi-circular canal

A. Membranous labyrinth

C. Section of macula

Otoconia

Gelatinous otolithicmembraneHair tuft

Hair cells

Supporting cells

Basement membrane

Nerve fibers

Hair cell (type II)

Supporting cell

Efferent nerveendings

Afferent nerveendings

Myelin sheath

D. Structure and innervationof hair cells

Hair cell (type I)

Supporting cells

Afferent nervecalyx

Efferent nerveending

Basementmembrane

Myelin sheath

Kinocilium

Stereocilia

Cuticle

Excitation

Inhibition

Basal body

Cuticle

Kinocilium

Stereocilia

Basal body

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NEUROPHYSIOLOGY Vestibular System: Vestibulospinal Tracts

Lowerlimb

ExcitatoryendingsInhibitoryendings

Ascending fibers in mediallongitudinal fasciculi

Motor neuron(controllingneck muscles)

Medial vestibulo-spinal fibers in mediallongitudinal fasciculi

Excitatoryendingsto backmuscles

Lowerpart ofcervicalspinal cord

To axialmuscles Inhibitory

endingLumbar part ofspinal cord

Medial

Lateral

Superior

Vestibular nuclei

Inferior

Tocerebellum

Vestibularganglionandnerve

Fibers from cristae(rotational stimuli)

Fibers from maculae(gravitational stimuli)

Lateralvestibulospinaltract

Excitatoryinterneuron

Inhibitoryinterneuron

To flexor muscles

To extensor muscles

Inhibitory ending??

? ?

To axial muscles

Excitatory ending

Lateral vestibulospinal tract

Inhibitory interneuron

Excitatory synapse

To flexor musclesTo extensor muscles

Somatotopicalpattern in lateralvestibular nucleus

Rostral

Caudal

TrunkUpperlimb

Ventral Dorsal

FIGURE 2.37 VESTIBULOSPINAL TRACTS•Sensory input from the vestibular apparatus is used to maintain sta-bility of the head and to maintain balance and posture. Axons con-vey vestibular information to the vestibular nuclei in the pons, andthen secondary axons distribute this information to five sites: spinal

cord (muscle control), cerebellum (vermis), reticular formation(vomiting center), extraocular muscles, and cortex (conscious per-ception). This figure shows only the spinal cord pathways.

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NEUROPHYSIOLOGYGustatory (Taste) System: Receptors

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

A. Tongue

Foliate papillae

Fungiformpapillae Vallate papillae

B. Sectionthrough vallatepapilla

Taste buds

Duct ofgustatory(Ebner’s)gland

C. Taste bud

Epithelium

Basement membrane

Nerve plexus

Nerve fibersemerging fromtaste buds

Microvilli

Taste cells

Taste pore

Microvilli

Epithelium

Desmosomes

Intercellular space Large nerve fiber

Small nerve fiber

Basement membrane

Collagen

Granules

Large nerve fiber Fibroblast

Schwann cell

FIGURE 2.38 TASTE RECEPTORS•Taste buds on the tongue respond to various chemical stimuli. Tastecells, like neurons, normally have a net negative charge internallyand are depolarized by stimuli, thus releasing transmitters that depo-

larize neurons connected to the taste cells. A single taste bud canrespond to more than one stimulus. The four traditional taste qualitiesthat are sensed are sweet, salty, sour, and bitter.

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NEUROPHYSIOLOGY Gustatory (Taste) System: Pathways

Lingual n.

Oticganglion

Chordatympani

Fungiform papillae

Foliate papillae

Valiate papillae

EpiglottisLarynx

Superior laryngeal n.

MesencephalicnucleusandMotor nucleus of trigeminal n.

Pons

Greater petrosal n.

Geniculate ganglion

Facial (VII) n.andNervus inermedius

Rostral part of nucleusof solitary tract

Glossopharyngeal (IX) n.

Lowerpart ofmedullaoblongata

Petrosal (inferior)ganglion ofglossopharyngeal n.

Nodose (inferior)ganglion of vagus n.

Vagus (X) n.

Ventral posteromedial (VPM)nucleus of thalamus

Sensory cortex (just belowface area)

Lateral hypothalamic area

Amygdala

Pontine taste area

Trigeminal (V) n.

Maxillary n.

Mandibular n.

Pterygo-palatineganglion

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 thepostcentral gyrus.

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NEUROPHYSIOLOGYOlfactory System: Receptors

Olfactorybulb

Lateral nasal wallSeptum

A. Distributionof olfactoryepithelium(blue area)

Cribriform plateof ethmoid bone

Cribriform plate

Schwann cell

Olfactory gland

Unmyelinatedolfactory axons

Basementmembrane

Sustentacularcells

Endoplasmicreticulum

Nucleus

Olfactory cells

Dendrites

Terminal bars(desmosomes)

Olfactory rod(vesicle)

Villi

Cilia

Mucus

B. Schema ofsection througholfactory mucosa

FIGURE 2.40 OLFACTORY RECEPTORS•The sensory cells that make up the olfactory epithelium respond toodorants by depolarizing. Like taste buds, an olfactory cell canrespond 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, pep-permint).

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NEUROPHYSIOLOGY Olfactory System: Pathway

FIGURE 2.41 OLFACTORY PATHWAY•Olfactory stimuli are detected by the nerve fibers of the olfactoryepithelium and conveyed to the olfactory bulb (detailed local cir-cuitry shown in upper left panel). Integrated signals pass along theolfactory tract and centrally diverge to pass to the anterior commis-

sure (some efferent projections course to the contralateral olfactorybulb, blue lines) or terminate in the ipsilateral olfactory trigone(olfactory tubercle). Axons then project to the primary olfactorycortex (piriform cortex), entorhinal cortex, and amygdala.

Fibers from contralateral olfactory bulb

Fibers to contralateral olfactory bulb

Anterior commissure

Medial olfactory stria

Anterior perforatedsubstance

Lateral olfactorystria

Lateral olfactorytract nucleus

Piriform lobe

Uncus

Amygdala(in phantom)

Entorhinal area

Efferent fibers

Afferent fibers

Granule cell (excited byand inhibiting to mitraland tufted cells)

Mitral cell

Recurrent process

Tufted cell

Periglom-erular cell

Glomerulus

Olfactorynerve fibers

Olfactory epithelium Olfactory tract

Olfactory nerves Anterior olfactory nucleus

Olfactory bulb Cribriform plate of ethmoid bone

Olfactory trigone andolfactory tubercle

©

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