Atlas de neuroanatomia y neurofisiologia

Atlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations

Illustrations by Frank H. Netter, MD John A. Craig, MD James Perkins, MS, MFA

Text by John T. Hansen, PhD Bruce M. Koeppen, MD, PhD

Atlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations

Copyright Š2002 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 any consequences arising from the use of the information contained herein, and make no warranty, expressed or implied, with respect to the contents of the publication.

Printed in U.S.A.

Foreword Frank Netter: The Physician, The Artist, The Art This selection of the art of Dr. Frank H. Netter on neuroanatomy and neurophysiology is drawn from the Atlas of Human Anatomy and Netter’s Atlas of Human Physiology. Viewing these pictures again prompts reflection on Dr. Netter’s work and his roles as physician and artist.

Frank H. Netter was born in 1906 in New York City. He pursued his artistic muse at the Sorbonne, the Art Student’s League, and the National Academy of Design before entering medical school at New York University, where he received his M.D. degree in 1931. During his student years, Dr. Netter’s notebook sketches attracted the attention of the medical faculty and other physicians, allowing him to augment his income by illustrating articles and textbooks. He continued illustrating as a sideline after establishing a surgical practice in 1933, but ultimately opted to give up his practice in favor of a full-time commitment to art. After service in the United States Army during the Second World War, Dr. Netter began his long collaboration with the CIBA Pharmaceutical Company (now Novartis Pharmaceuticals). This 45-year partnership resulted in the production of the extraordinary collection of medical art so familiar to physicians and other medical professionals worldwide.

When Dr. Netter’s work is discussed, attention is focused primarily on Netter the artist and only secondarily on Netter the physician. As a student of Dr. Netter’s work for more than forty years, I can say that the true strength of a Netter illustration was always established well before brush was laid to paper. In that respect each plate is more of an intellectual than an artistic or aesthetic exercise. It is easy to appreciate the aesthetic qualities of Dr. Netter’s work, but to overlook its intellectual qualities is to miss the real strength and intent of the art. This intellectual process requires thorough understanding of the topic, as Dr. Netter wrote: “Strange as it may seem, the hardest part of making a medical picture is not the drawing at all. It is the planning, the conception, the determination of point of view and the approach which will best clarify the subject which takes the most effort.”

Years before the inception of “the integrated curriculum,” Netter the physician realized that a good medical illustration can include clinical information and physiologic functions as well as anatomy. In pursuit of this principle Dr. Netter often integrates pertinent basic and clinical science elements in his anatomic interpretations. Although he was chided for this heresy by a prominent European anatomy professor, many generations of students training to be physicians rather than anatomists have appreciated Dr. Netter’s concept.

The integration of physiology and clinical medicine with anatomy has led Dr. Netter to another, more subtle, choice in his art. Many texts and atlases published during the period of Dr. Netter’s career depict anatomy clearly based on cadaver specimens with renderings of shrunken and shriveled tissues and organs. Netter the physician chose to render “live” versions of these structures—not shriveled, colorless, formaldehyde-soaked tissues, but plump, robust organs, glowing with color!

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

John A. Craig, MD Austin, Texas

This volume brings together two distinct but related aspects of the work of Frank H. Netter, MD, and associated artists. Netter is best known as the creator of the Atlas of Human Anatomy, a comprehensive textbook of gross anatomy that has become the standard atlas for students of the subject. But Netter’s work included far more than anatomical art. In the pages of Clinical Symposia, a series of monographs published over a period of more than 50 years, and in The Netter Collection of Medical Illustrations, this premier medical artist created superb illustrations of biological and physiological processes, disease pathology, clinical presentations, and medical procedures.

As a service to the medical community, Novartis Pharmaceuticals has commissioned this special edition of Netter’s work, which includes his beautiful and instructive illustrations of nervous system anatomy as well as his depictions of neurophysiological concepts and functions. We hope that readers will find Dr. Netter’s renderings of neurological form and function interesting and useful.

Click any title below to link to that plate.

Part 1 Neuroanatomy Cerebrum—Medial Views . . . . . . . . . . . . . . . . . 2 Cerebrum—Inferior View. . . . . . . . . . . . . . . . . . 3 Basal Nuclei (Ganglia). . . . . . . . . . . . . . . . . . . . 4 Thalamus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Cerebellum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Brainstem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Fourth Ventricle and Cerebellum . . . . . . . . . . . 8 Accessory Nerve (XI) . . . . . . . . . . . . . . . . . . . . 9 Arteries to Brain and Meninges . . . . . . . . . . . 10 Arteries to Brain: Schema . . . . . . . . . . . . . . . . 11

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

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

Autonomic Nerves and Ganglia of Abdomen. . . . . . . . . . . . . . . 36

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

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

Arteries of Brain: Frontal View and Section . . 14

Nerves of Stomach and Duodenum (continued) . . . . . . . . . . . . 38

Arteries of Brain: Lateral and Medial Views . . . . . . . . . . . . . . . 15

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

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

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

Veins of Posterior Cranial Fossa . . . . . . . . . . . 17 Deep Veins of Brain. . . . . . . . . . . . . . . . . . . . . 18

Nerves of Kidneys, Ureters and Urinary Bladder . . . . . . . . . . . . 41

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

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

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

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

Arteries and Veins of Hypothalamus and Hypophysis . . . . . . . . 21

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

Relation of Spinal Nerve Roots to Vertebrae . . . 22

Radial Nerve in Arm and Nerves of Posterior Shoulder . . . . . . . . 46

Autonomic Nervous System: General Topography. . . . . . . . . . . . . . . . . . . 23 Spinal Nerve Origin: Cross Sections. . . . . . . . 24 Olfactory Nerve (I): Schema . . . . . . . . . . . . . . 25 Optic Nerve (II) (Visual Pathway): Schema . . . . . . . . . . . . . . 26

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

Radial Nerve in Forearm . . . . . . . . . . . . . . . . . 47 Sciatic Nerve and Posterior Cutaneous Nerve of Thigh . . . . . . . . . . . . . . 48 Tibial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Common Fibular (Peroneal) Nerve. . . . . . . . . 50

NEUROANATOMY Sagittal section of brain in situ

Cingulate gyrus Cingulate sulcus Medial frontal gyrus Sulcus of corpus callosum Fornix Septum pellucidum Interventricular foramen (Monro) Interthalamic adhesion Thalamus and 3rd ventricle Subcallosal (parolfactory) area

Anterior commissure Subcallosal gyrus Hypothalamic sulcus Lamina terminalis Supraoptic recess Optic chiasm Tuber cinereum Hypophysis (pituitary gland) Mammillary body Cerebral peduncle Pons

Medial surface of cerebral hemisphere: brainstem excised Cingulate gyrus Mammillothalamic fasciculus Mammillary body

Cerebrum: Medial Views

Paracentral sulcus Central sulcus (Rolando) Paracentral lobule Marginal sulcus Corpus callosum Precuneus Superior sagittal sinus Choroid plexus of 3rd ventricle Stria medullaris of thalamus Parietooccipital sulcus Cuneus Habenular commissure Pineal body Posterior commissure Calcarine sulcus Straight sinus in tentorium cerebelli

Cerebral aqueduct (Sylvius)

Great cerebral vein (Galen) Superior colliculus Inferior colliculus Tectal (quadrigeminal) plate Cerebellum Superior medullary velum 4th ventricle and choroid plexus Inferior medullary velum Medulla oblongata Genu Rostrum Trunk Splenium

of corpus callosum

Isthmus of cingulate gyrus Parietooccipital sulcus Cuneus

Uncus

Calcarine sulcus

Optic nerve (II) Lingual gyrus

Olfactory tract

Crus Body Column

Collateral sulcus Rhinal sulcus Medial occipitotemporal gyrus Occipitotemporal sulcus Lateral occipitotemporal gyrus

2

of fornix

Fimbria of hippocampus Dentate gyrus Parahippocampal gyrus

NEUROANATOMY

Cerebrum: Inferior View

Sectioned brainstem

Frontal pole of cerebrum Straight gyrus Olfactory sulcus Orbital sulci

Longitudinal cerebral fissure Genu of corpus callosum Lamina terminalis Olfactory bulb Olfactory tract

Orbital gyri

Optic chiasm

Temporal pole

Optic nerve (II) (cut)

Lateral sulcus (Sylvius)

Hypophysis (pituitary gland)

Inferior temporal sulcus Inferior temporal gyrus

Anterior perforated substance Optic tract Tuber cinereum Mammillary body

Inferior (inferolateral) margin of cerebrum

Posterior perforated substance (in interpeduncular fossa)

Rhinal sulcus

Cerebral crus Uncus

Lateral geniculate body

Inferior temporal gyrus

Substantia nigra Medial geniculate body

Occipitotemporal sulcus

Red nucleus Lateral occipitotemporal gyrus

Pulvinar of thalamus Superior colliculus (of corpora quadrigemina)

Collateral sulcus

Cerebral aqueduct Parahippocampal gyrus Splenium of corpus callosum Medial occipitotemporal gyrus Calcarine sulcus

Apex of cuneus Occipital pole of cerebrum Longitudinal cerebral fissure

Isthmus of cingulate gyrus

3

NEUROANATOMY

Horizontal sections through cerebrum

Basal Nuclei (Ganglia)

A

B

Genu of corpus callosum

Head of caudate nucleus

Lateral ventricle

Anterior limb of internal capsule

Genu

Septum pellucidum

Posterior limb Column of fornix

Putamen Globus pallidus

Insula (island of Reil)

Lentiform nucleus

3rd ventricle Interthalamic adhesion

External capsule

Thalamus

Claustrum

Crus of fornix

Retrolenticular part of internal capsule

Choroid plexus of lateral ventricle

Tail of caudate nucleus Hippocampus and fimbria

Splenium of corpus callosum

Occipital (posterior) horn of lateral ventricle Habenula

Organization of basal nuclei (ganglia)

A

B

Caudate Putamen Globus nucleus pallidus

Striatum

Lentiform nucleus

Corpus striatum Basal nuclei (ganglia)

Pineal body

Cleft for internal capsule

Caudate nucleus Levels of sections above

Body Head

A B

Thalamus

A B Pulvinar

Lentiform nucleus (globus pallidus medial to putamen) Amygdaloid body

Medial geniculate body Lateral geniculate body Tail of caudate nucleus

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

4

NEUROANATOMY

Thalamus

Corpus callosum (cut)

Interventricular foramen (Monro)

Head of caudate nucleus

Tela choroidea (cut edge) of 3rd ventricle

Septum pellucidum

3rd ventricle

Columns of fornix

Choroid plexus

Anterior tubercle

Superior thalamostriate vein

Stria terminalis

Pes hippocampi

Interthalamic adhesion

Temporal (inferior) horn of lateral ventricle

Lamina affixa

Internal cerebral vein

Stria medullaris

Dentate gyrus

Habenular trigone

Collateral eminence

Pulvinar (retracted)

Hippocampus

Lateral geniculate body

Fimbria of hippocampus

Medial geniculate body

Posterior commissure

Brachium of superior colliculus

Habenular commissure

Brachium of inferior colliculus

Pineal body Collateral trigone

Superior colliculus

Calcar avis

Inferior colliculus

Occipital (posterior) horn of lateral ventricle

Cerebellum

Calcarine sulcus 3rd ventricle

Internal medullary lamina

Interthalamic adhesion

a

Pulvinar

rio

r

MD

LP

M

Intralaminar nuclei

Inte

LP

3rd ventricle

VPL M

External medullary lamina

VP

Median nuclei

Schematic section through thalamus (at level of broken line shown in figure at right)

Thalamic nuclei CM LD LP M MD VA VI VL VP VPL VPM

Centromedian Lateral dorsal Lateral posterior Medial Medial dorsal Ventral anterior Ventral intermedial Ventral lateral Ventral posterior Ventral posterolateral Ventral posteromedial

VL

VP

Reticular nucleus

VP

CM

rn

L

VA

La

m

in

n te An dia Me ial d na Me llar y lami u d D e L al m

VP

M

VI

Pulvinar Lateral geniculate body Medial geniculate body

Schematic representation of thalamus (external medullary lamina and reticular nuclei removed) Lateral nuclei Medial nuclei Anterior nuclei

5

NEUROANATOMY

Cerebellum

Superior surface Anterior cerebellar notch

Anterior lobe Quadrangular lobule (H IV-V)

Central lobule (II & III)

Primary fissure Horizontal fissure

Culmen (IV & V)

Simple lobule (H VI)

Superior vermis

Posterior lobe

Declive (VI)

Postlunate fissure Folium (VII A)

Superior semilunar (anseriform) lobule (H VII A) Horizontal fissure Inferior semilunar (caudal) lobule (H VII B)

Posterior cerebellar notch Central lobule Superior vermis

Anterior lobe

Inferior surface

Wing of central lobule

Lingula (I)

Superior Middle Inferior

Superior medullary velum Flocculus (H X)

Flocculonodular lobe

4th ventricle

Posterolateral (dorsolateral) fissure

Inferior medullary velum

Retrotonsillar fissure

Nodule (X) Inferior vermis

Cerebellar peduncles

Posterior lobe

Uvula (IX) Pyramid (VIII) Tuber (VII B) Posterior cerebellar notch

Decussation of superior cerebellar peduncles

Tonsil Biventer lobule (H VIII) Secondary (postpyramidal) fissure Horizontal fissure Inferior semilunar (caudal) lobule (H VII B) Cerebral crus Medial longitudinal fasciculus

4th ventricle Nuclear layer of medulla oblongata

Superior medullary velum Fastigial Cerebellar nuclei

Superior cerebellar peduncle

Globose Lingula (I) Dentate Vermis

Emboliform

Section in plane of superior cerebellar peduncle

6

NEUROANATOMY

Brainstem

Thalamus (cut surface)

Posterolateral view

Lateral geniculate body Optic tract

Pulvinars of thalami Pineal body

Medial geniculate body

Superior colliculi

Brachia of superior and inferior colliculi

Inferior colliculi

Cerebral crus

Trochlear nerve (IV)

Pons

Superior medullary velum

Trigeminal nerve (V)

Superior cerebellar peduncle

Middle cerebellar peduncle

Rhomboid fossa of 4th ventricle

Vestibulocochlear nerve (VIII) Facial nerve (VII)

Glossopharyngeal (IX) and vagus (X) nerves

Inferior cerebellar peduncle

Cuneate tubercle

Hypoglossal nerve (XII)

Gracile tubercle Accessory nerve (XI)

Dorsal roots of 1st spinal nerve (C1) Cuneate fasciculus Gracile fasciculus

Olfactory tract

Anterior view

Anterior perforated substance Infundibulum (pituitary stalk)

Optic chiasm

Mammillary bodies

Optic tract

Temporal lobe (cut surface) Oculomotor nerve (III)

Tuber cinereum

Trochlear nerve (IV)

Cerebral crus

Trigeminal nerve (V) Abducent nerve (VI)

Lateral geniculate body

Facial nerve (VII) and intermediate nerve

Posterior perforated substance

Vestibulocochlear nerve (VIII)

Pons

Flocculus of cerebellum Middle cerebellar peduncle Olive

Choroid plexus of 4th ventricle Glossopharyngeal nerve (IX)

Pyramid Ventral roots of 1st spinal nerve (C1) Decussation of pyramids

Vagus nerve (X) Hypoglossal nerve (XII) Accessory nerve (XI)

7

NEUROANATOMY

Fourth Ventricle and Cerebellum

Habenular trigone

Posterior view

Medial Lateral

3rd ventricle

Geniculate bodies

Dorsal median sulcus

Pulvinar of thalamus

Superior cerebellar peduncle

Pineal body

Locus ceruleus

Superior colliculus

Medial eminence

Inferior colliculus

Facial colliculus

Trochlear nerve (IV)

Vestibular area

Superior medullary velum

Dentate nucleus of cerebellum

Superior Middle Inferior

Cerebellar peduncles

Striae medullares

Lateral recess

Tenia of 4th ventricle

Superior fovea

Cuneate tubercle

Sulcus limitans

Gracile tubercle

Inferior fovea

Dorsal median sulcus

Trigeminal tubercle

Lateral funiculus

Hypoglossal trigone Vagal trigone

Cuneate fasciculus Gracile fasciculus

Obex Interthalamic adhesion

Median sagittal section

Posterior commissure

Body of fornix

Habenular commissure

Thalamus (in 3rd ventricle)

Pineal body

Interventricular foramen (Monro)

Splenium of corpus callosum Great cerebral vein (Galen)

Anterior commissure Lamina terminalis

Lingula (I) Central lobule (II-III) Culmen (IV-V) Declive (VI) Folium (VII A)

Hypothalamic sulcus Cerebral peduncle Cerebral aqueduct (Sylvius) Superior colliculus Tectal (quadrigeminal) plate

Superior medullary velum

Inferior colliculus Pons

Inferior medullary velum

Medial longitudinal fasciculus

Tuber (VII B)

4th ventricle

Pyramid (VIII)

Choroid plexus of 4th ventricle

Uvula (IX) Nodulus (X)

Medulla oblongata Median aperture (foramen of Magendie) Decussation of pyramids Central canal of spinal cord

8

Vermis of cerebellum

Choroid plexus of 4th ventricle Tonsil of cerebellum

Vermis of cerebellum

NEUROANATOMY

Accessory Nerve (XI): Schema

Nucleus ambiguus Vagus nerve (X)

Cranial root of accessory nerve (joins vagus nerve and via recurrent laryngeal nerve supplies muscles of larynx, except cricothyroid)* Spinal root of accessory nerve Foramen magnum

Jugular foramen Superior ganglion of vagus nerve Accessory nerve (XI)*

Inferior ganglion of vagus nerve

C1 spinal nerve C2 spinal nerve Accessory nerve (to sternocleidomastoid and 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.

9

NEUROANATOMY

Left middle meningeal artery Posterior cerebral artery Superior cerebellar artery Basilar artery

Arteries to Brain and Meninges

Middle cerebral artery Anterior cerebral artery Anterior communicating artery Ophthalmic artery

Left labyrinthine (internal acoustic) artery

Posterior communicating artery

Mastoid branch of left occipital artery

Cavernous sinus Anterior inferior cerebellar artery

Middle meningeal artery

Posterior meningeal branch of left ascending pharyngeal artery Posterior inferior cerebellar artery Left and right vertebral arteries (intracranial part)

Maxillary artery Superficial temporal artery

Posterior meningeal branch of vertebral artery

External carotid artery

Anterior meningeal branch of vertebral artery Posterior auricular artery

Facial artery

Occipital artery Internal carotid artery Carotid sinus Carotid body Vertebral artery (cervical part) Transverse process of C6 Deep cervical artery Supreme intercostal artery Costocervical trunk Subclavian artery

10

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

NEUROANATOMY

Arteries to Brain: Schema

Anterior communicating artery

Anterior cerebral artery 1

Ophthalmic artery

Middle cerebral artery

Supraorbital artery

Posterior communicating artery

Supratrochlear artery Caroticotympanic branch of internal carotid artery

3

3

2

3

Lacrimal artery 1

Dorsal nasal artery

Posterior cerebral artery

Middle meningeal artery

3

Superior cerebellar artery

Angular artery Anterior tympanic artery

Superficial temporal artery

1 1

Middle meningeal artery

Posterior auricular artery

4

Facial artery

Maxillary artery Basilar artery

5

4

5

Occipital artery Lingual artery

Anterior inferior cerebellar artery

5

Posterior inferior cerebellar artery

5

Ascending pharyngeal artery Anterior spinal artery

5

External carotid artery

Spinal segmental medullary branches

5

Vertebral artery

5

Internal carotid artery

Common carotid artery

Superior thyroid artery

Deep cervical artery 5

Common carotid artery

Transverse cervical artery Suprascapular artery

Vertebral artery

Supreme intercostal artery Ascending cervical artery

Costocervical trunk

Inferior thyroid artery Thyrocervical trunk

Subclavian artery

Subclavian artery

Internal thoracic artery

Brachiocephalic trunk

Arch Aorta

Descending Ascending

Anastomoses 1 2 3 4 5

Right–Left Carotid–Vertebral Internal carotid–External carotid Subclavian–Carotid Subclavian–Vertebral

11

NEUROANATOMY

Arteries of Brain: Inferior Views

Medial frontobasal (orbitofrontal) artery Anterior communicating artery Anterior cerebral artery Distal medial striate artery (recurrent artery of Heubner) Internal carotid artery Anterolateral central (lenticulostriate) arteries Middle cerebral artery Lateral frontobasal (orbitofrontal) artery Prefrontal artery Anterior choroidal artery Posterior communicating artery Posterior cerebral artery Superior cerebellar artery Basilar artery Pontine arteries Labyrinthine (internal acoustic) artery Anterior inferior cerebellar artery Vertebral artery Anterior spinal artery Posterior inferior cerebellar artery (PICA) (cut) Posterior spinal artery

Distal medial striate artery (recurrent artery of Heubner) Anterior communicating artery Anterior cerebral artery Middle cerebral artery Posterior communicating artery Anterior choroidal artery Optic tract Posterior cerebral artery Cerebral crus Lateral geniculate body Posterior medial choroidal artery Posterior lateral choroidal artery Choroid plexus of lateral ventricle Medial geniculate body Pulvinar of thalamus Lateral ventricle

12

Cerebral arterial circle (Willis) (broken line)

NEUROANATOMY

Cerebral Arterial Circle (Willis)

Vessels dissected out: inferior view Anterior cerebral artery (A2 segment)

Distal medial striate artery (recurrent artery of Heubner) Anteromedial central (perforating) arteries

Anterior communicating artery Anterior cerebral artery (A1 segment)

Hypothalamic artery Anterolateral central (lenticulostriate) arteries

Ophthalmic artery Internal carotid artery Middle cerebral artery

Superior hypophyseal artery

Posterior communicating artery

Inferior hypophyseal artery Anterior choroidal artery

Posterior cerebral artery (P2 segment) (P1 segment) Superior cerebellar artery Basilar artery Pontine arteries Anterior inferior cerebellar artery

Thalamotuberal (premammillary) artery Posteromedial central (perforating) arteries Thalamoperforating artery Posteromedial central (paramedian) arteries Labyrinthine (internal acoustic) artery

Vertebral artery

Vessels in situ: inferior view Anterior cerebral artery Hypothalamic artery

Anterior communicating artery Optic chiasm Cavernous sinus

Internal carotid artery Superior hypophyseal artery Middle cerebral artery Inferior hypophyseal artery Posterior communicating artery

Infundibulum (pituitary stalk) and long hypophyseal portal veins Adenohypophysis (anterior lobe of pituitary gland) Neurohypophysis (posterior lobe of pituitary gland) Posteromedial central (perforating) arteries

Efferent hypophyseal veins Superior cerebellar artery Posterior cerebral artery

Basilar artery

13

NEUROANATOMY

Corpus callosum

Arteries of Brain: Frontal View and Section

Paracentral artery Medial frontal branches

Anterolateral central (lenticulostriate) arteries

Pericallosal artery

Lateral frontobasal (orbitofrontal) artery

Callosomarginal artery Polar frontal artery

Prefrontal artery Anterior cerebral arteries

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

Medial frontobasal (orbitofrontal) artery

Anterior parietal (postcentral sulcal) artery

Distal medial striate artery (recurrent artery of Heubner)

Posterior parietal artery

Internal carotid artery

Branch to angular gyrus

Anterior choroidal artery

Temporal branches (anterior, middle and posterior)

Posterior cerebral artery Superior cerebellar artery

Middle cerebral artery and branches (deep in lateral cerebral [sylvian] sulcus)

Basilar and pontine arteries Labyrinthine (internal acoustic) artery

Anterior communicating artery Posterior communicating artery Anterior inferior cerebellar artery

Vertebral artery Posterior inferior cerebellar artery Anterior spinal artery

Posterior spinal artery Falx cerebri Corpus striatum (caudate and lentiform nuclei) Anterolateral central (lenticulostriate) arteries Insula (island of Reil) Limen of insula Precentral (pre-rolandic), central (rolandic) sulcal and parietal arteries Lateral cerebral (sylvian) sulcus Temporal branches of middle cerebral artery Temporal lobe Middle cerebral artery Internal carotid artery

14

Callosomarginal arteries and Pericallosal arteries (branches of anterior cerebral arteries) Trunk of corpus callosum Internal capsule Septum pellucidum Rostrum of corpus callosum Anterior cerebral arteries Distal medial striate artery (recurrent artery of Heubner) Anterior communicating artery Optic chiasm

NEUROANATOMY

Arteries of Brain: Lateral and Medial Views

Anterior parietal (postcentral sulcal) artery

Posterior parietal artery

Central (rolandic) sulcal artery

Branch to angular gyrus

Precentral (pre-rolandic) sulcal artery

Terminal branches of posterior cerebral artery

Prefrontal sulcal artery Terminal branches of anterior cerebral artery Lateral frontobasal (orbitofrontal) artery Left middle cerebral artery Left anterior cerebral artery

Occipitotemporal branches

Anterior communicating artery

Posterior temporal branch

Right anterior cerebral artery

Middle temporal branch Left internal carotid artery Polar temporal artery

Medial frontal branches

Posterior Intermediate Anterior

Pericallosal artery

Superior and inferior terminal branches (trunks) Anterior temporal branch Paracentral artery Cingular branches Right posterior cerebral artery Precuneal artery

Callosomarginal artery Polar frontal artery

Dorsal branch to corpus callosum Parietooccipital branch Calcarine branch

Right anterior cerebral artery Medial frontobasal (orbitofrontal) artery Anterior communicating artery (cut) Medial occipital artery Distal medial striate artery (recurrent artery of Heubner)

Posterior temporal branch Anterior temporal branch

Right internal carotid artery

Posterior communicating artery

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

15

NEUROANATOMY

Arteries of Posterior Cranial Fossa

Thalamogeniculate arteries

Lateral and medial geniculate bodies of left thalamus Choroid plexuses of lateral ventricles

Anterior choroidal artery

Pulvinars of left and right thalami

Crura of fornix

Splenium of corpus callosum

Anterolateral central (lenticulostriate) arteries

Occipital (posterior) horn of right lateral ventricle Right dorsal branch to corpus callosum (posterior pericallosal artery)

Heads of caudate nuclei Septum pellucidum

Parietooccipital

Corpus callosum

Calcarine

Branches of right posterior cerebral artery

Anterior cerebral arteries Longitudinal cerebral fissure

Superior colliculi Superior vermian branch

Optic nerve (II) IV

Ophthalmic artery

III

Posterior medial choroidal artery to choroid plexus of 3rd ventricle

V

Anterior cerebral artery Middle cerebral artery

VIII

Posterior communicating artery

VII

Posterior lateral choroidal artery

VI

Lateral (marginal) branch

IX X

Thalamoperforating arteries

Inferior vermian artery (phantom)

Left internal carotid artery XI

Basilar artery

Choroidal branch to 4th ventricle (phantom) and Cerebellar tonsillar branch of posterior inferior cerebellar artery

Pontine arteries Labyrinthine (internal acoustic) artery Posterior cerebral artery Superior cerebellar artery Anterior inferior cerebellar artery

Outline of 4th ventricle (broken line) Posterior meningeal branch of vertebral artery Posterior inferior cerebellar artery (PICA)

Anterior meningeal branch of vertebral artery Temporal branches of posterior cerebral artery Anterior spinal artery

16

Left posterior spinal artery Left vertebral artery

NEUROANATOMY

Veins of Posterior Cranial Fossa

Left superior and inferior colliculi

Left pulvinar

Basal vein (Rosenthal)

Right pulvinar Internal cerebral veins

Posterior mesencephalic vein

Splenium of corpus callosum

Medial geniculate body

Great cerebral vein (Galen)

Lateral mesencephalic vein

Dorsal vein of corpus callosum

Lateral geniculate body

Inferior sagittal sinus

Left thalamus (cut surface)

Straight sinus Falx cerebri

Optic tract

Confluence of sinuses

Tentorium cerebelli (cut)

Inferior thalamostriate veins

Left transverse sinus (cut)

Deep middle cerebral vein (cut)

Superior sagittal sinus

Anterior cerebral vein Optic nerve (II)

C

C

CL

D F TU

L N

Superior vermian vein

P U

Anterior pontomesencephalic vein

Inferior vermian vein Falx cerebelli (cut) and occipital sinus

T

Inferior cerebellar hemispheric veins

Trigeminal nerve (V) Transverse pontine vein

Intraculminate vein Superior cerebellar vein (inconstant)

Petrosal vein (draining to superior petrosal sinus)

Preculminate vein

Lateral pontine vein

Precentral cerebellar vein Superior retrotonsillar vein

Anteromedian medullary vein Vein of lateral recess of 4th ventricle Superior, middle and inferior cerebellar peduncles Anterior spinal vein

(Inferior retrotonsillar) vein of cerebellomedullary cistern Posterior spinal vein 4th ventricle

Parts of cerebellum L CL C D F

Lingula Central lobule Culmen Declive Folium

TU Tuber P Pyramid U Uvula N Nodule T Tonsil

17

NEUROANATOMY

Deep Veins of Brain

Longitudinal cerebral fissure Anterior cerebral veins Rostrum of corpus callosum Septum pellucidum Anterior vein of septum pellucidum Head of caudate nucleus Anterior vein of caudate nucleus Transverse veins of caudate nucleus Interventricular foramen (Monro) Columns of fornix Superior thalamostriate vein Superior choroid vein and choroid plexus of lateral ventricle Thalamus Tela choroidea of 3rd ventricle Lateral direct vein Posterior vein of caudate nucleus Internal cerebral veins Basal vein (Rosenthal) Great cerebral vein (Galen) Inferior sagittal sinus Straight sinus Tentorium cerebelli Transverse sinus Confluence of sinuses Superior sagittal sinus

Dissection: superior view Uncal vein Anterior cerebral vein Superficial middle cerebral vein (draining to sphenoparietal sinus)

Optic chiasm

Deep middle cerebral vein Cerebral crus Basal vein (Rosenthal) Lateral geniculate body Medial geniculate body

Inferior cerebral veins

Pulvinar of thalamus Splenium of corpus callosum Great cerebral vein (Galen)

Dissection: inferior view

18

Inferior anastomotic vein (LabbĂŠ)

NEUROANATOMY

Subependymal Veins of Brain

Posterior veins of septum pellucidum Superior thalamic veins Superior choroid vein

Lateral direct vein Posterior terminal vein of caudate nucleus (posterior part of thalamostriate vein) Internal cerebral veins (right and left)

Transverse veins of caudate nucleus

Medial (atrial) vein of lateral ventricle

Superior thalamostriate vein

Lateral (atrial) vein of lateral ventricle

Lateral ventricle

Splenium of corpus callosum

Anterior vein of caudate nucleus

Great cerebral vein (Galen)

Anterior vein of septum pellucidum

Dorsal vein of corpus callosum

Genu of corpus callosum

Inferior sagittal sinus Internal occipital vein Straight sinus Occipital (posterior) horn of lateral ventricle

Interventricular foramen (Monro) Anterior commissure Interthalamic adhesion Anterior cerebral vein Optic chiasm Cerebellum

3rd ventricle Deep middle cerebral vein Inferior thalamostriate veins Basal vein (Rosenthal) Temporal (inferior) horn of lateral ventricle Posterior mesencephalic vein

Superior vermian 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

19

NEUROANATOMY

Hypothalamus and Hypophysis

Septum pellucidum Thalamus Fornix Hypothalamic sulcus Anterior commissure

Paraventricular Posterior Dorsomedial

Principal nuclei of hypothalamus

Supraoptic Ventromedial Arcuate (infundibular) Mammillary Mammillothalamic tract Optic chiasm Infundibulum (pituitary stalk)

Dorsal longitudinal fasciculus and other descending pathways

Hypophysis (pituitary gland)

Lamina terminalis

Hypothalamic sulcus

Paraventricular hypothalamic nucleus Supraoptic hypothalamic nucleus Supraopticohypophyseal tract Tuberohypophyseal tract

Mammillary body

Hypothalamohypophyseal tract Infundibulum (pituitary stalk)

Arcuate (infundibular) nucleus

Pars tuberalis

Adenohypophysis (anterior lobe of pituitary gland)

Fibrous trabecula

Median eminence of tuber cinereum Infundibular stem

Pars intermedia Pars distalis

Infundibular process Cleft

20

Neurohypophysis (posterior lobe of pituitary gland)

Arteries and Veins of Hypothalamus and Hypophysis

NEUROANATOMY

Hypothalamic vessels

Primary plexus of hypophyseal portal system Superior hypophyseal artery

Long hypophyseal portal veins

Artery of trabecula Short hypophyseal portal veins Trabecula (fibrous tissue) Efferent hypophyseal vein to cavernous sinus

Secondary plexus of hypophyseal portal system

Adenohypophysis (anterior lobe of pituitary gland)

Efferent hypophyseal vein to cavernous sinus

Neurohypophysis (posterior lobe of pituitary gland)

Capillary plexus of infundibular process

Efferent hypophyseal vein to cavernous sinus

Efferent hypophyseal veins to cavernous sinus

Inferior hypophyseal artery

21

NEUROANATOMY

Relation of Spinal Nerve Roots to Vertebrae

C1 C2 C2 C3 C3 C4 C4 C5 C5 C6 C6 C7 C7 C8 T1 T1 T2 T2 T3 T3 T4 T4 T5 T5 T6 T6 T7 T7 T8 T8 T9 T9 T10 T10 T11 T11 T12 T12 L1

Base of skull Cervical enlargement

Lumbar enlargement

L4

C1 spinal nerve exits above C1 vertebra

C1

L4 L5 C8 spinal nerve exits below C7 vertebra (there are 8 cervical nerves but only 7 cervical vertebrae)

L5

S1 S2 Lumbar disc protrusion does not usually affect nerve exiting above disc. Lateral protrusion at disc level L4–5 affects L5 spinal nerve, not L4 spinal nerve. Protrusion at disc level L5–S1 affects S1 spinal nerve, not L5 spinal nerve

L4 Conus medullaris (termination of spinal cord)

L1

L4

L2 L2

L5

L3 L3 Internal terminal filum (pial part)

L5 Cauda equina

L4 L4 S1

L5 L5 Sacrum External terminal filum (dural part)

S2

S1

S3

Termination of dural sac S4 S5 Coccygeal nerve Coccyx Cervical nerves Thoracic nerves Lumbar nerves Sacral and coccygeal nerves

22

S2 S3 S4 S5

Coccygeal nerve

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

Autonomic Nervous System: General Topography

Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) 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 T6 spinal 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 parasympathetic outflow) Sciatic nerve Inferior hypogastric (pelvic) plexus

NEUROANATOMY

Ciliary ganglion Pterygopalatine ganglion Otic ganglion Chorda tympani nerve Lingual nerve Submandibular ganglion Pharyngeal and superior laryngeal branches of vagus nerve Recurrent laryngeal branch of vagus nerve Superior cervical Inferior cervical Thoracic

Cardiac branches of vagus nerve

Cardiac plexus Anterior Posterior

Pulmonary plexuses

Esophageal plexus Thoracic aortic plexus Anterior vagal trunk Posterior vagal trunk Celiac ganglion Celiac trunk and plexus Superior mesenteric ganglion Superior mesenteric artery and plexus Intermesenteric (abdominal aortic) plexus Inferior mesenteric ganglion Inferior mesenteric artery and plexus Superior hypogastric plexus Parasympathetic branch from inferior hypogastric plexus to descending colon Hypogastric nerves Rectal plexus Vesical plexus

Sympathetic fibers Parasympathetic fibers

Prostatic plexus

23

NEUROANATOMY

Spinal Nerve Origin: Cross Sections

Section through thoracic vertebra

Aorta Body of vertebra

Fat in epidural space

Dura mater

Sympathetic ganglion

Arachnoid mater* Ventral root

Subarachnoid space

White and gray rami communicantes

Pia mater* Recurrent meningeal branches of spinal nerve

Spinal nerve Ventral ramus (intercostal nerve) Dorsal ramus

Pleura Lung

Spinal sensory (dorsal root) ganglion Dorsal root Lateral horn of gray matter of spinal cord

Section through lumbar vertebra Lateral branch Sympathetic ganglion

Medial branch

Dura mater Arachnoid mater

Gray ramus communicans

Internal vertebral (epidural) venous plexus

Ventral root Fat in epidural space

Spinal nerve Ventral ramus (contributes to lumbar plexus) Dorsal ramus

Dorsal and ventral roots of lumbar and sacral spinal nerves forming cauda equina

Spinal sensory (dorsal root) ganglion Dorsal root Conus medullaris *Leptomeninges

24

of dorsal ramus of spinal nerve

NEUROANATOMY

Olfactory Nerve (I): Schema

Subcallosal (parolfactory) area Septal area and nuclei

Olfactory bulb cells: schema Fibers from Fibers to

Efferent fibers to olfactory bulb Afferent fibers from bulb to central connections and contralateral bulb

Contralateral olfactory bulb

Anterior commissure Medial olfactory stria

Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process Tufted cell Periglomerular cell Glomerulus Olfactory nerve fibers

Olfactory cells Olfactory mucosa

Olfactory tract Olfactory trigone and olfactory tubercle

Olfactory nerves (I) Lateral olfactory stria

Uncus

Olfactory bulb Lateral olfactory tract nucleus Cribriform plate of ethmoid bone Anterior perforated substance Anterior olfactory nucleus Amygdaloid body (phantom) Piriform lobe

Hippocampal fimbria Dentate gyrus Parahippocampal gyrus

25

NEUROANATOMY

Optic Nerve (II) (Visual Pathway): Schema

G

Central darker circle represents macular zone

G A B

A

Overlapping visual fields

Lighter shades represent monocular fields

B

Each quadrant a different color

H

H

R RC

P

Projection on right retina

Projection on left retina

C

P

Choroid

Choroid

Periphery

Macula

Optic nerves (II) Optic chiasm

Structure of retina: schema A B C G H P R

Amacrine cells Bipolar cells Cones Ganglion cells Horizontal cells Pigment cells Rods

Projection on left dorsal lateral geniculate nucleus

Optic tracts

Projection on right dorsal lateral geniculate nucleus

Lateral geniculate bodies Optic radiation

Optic radiation

Calcarine sulcus Calcarine sulcus

Projection on left occipital lobe

26

Projection on right occipital lobe

NEUROANATOMY

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

Long ciliary nerve Short ciliary nerves Anterior ethmoidal nerve Superior oblique muscle Levator palpebrae superioris muscle Superior rectus muscle

Ciliary ganglion Posterior ethmoidal nerve

Abducent nucleus

Sensory root of ciliary ganglion Trochlear nucleus Sympathetic root of ciliary ganglion Oculomotor nucleus

Superior division of oculomotor nerve

Accessory oculomotor (Edinger-Westphal) nucleus (parasympathetic)

Frontal nerve (cut) Lacrimal nerve (cut) Nasociliary nerve

Trochlear nerve (IV)

Oculomotor nerve (III) Ophthalmic nerve (V1)

Abducent nerve (VI)

Infraorbital nerve Zygomatic nerve (cut) Inferior oblique muscle Ciliary muscle

Pterygopalatine ganglion Inferior division of oculomotor nerve

Dilator muscle of pupil Sphincter muscle of pupil

Medial rectus muscle Inferior rectus muscle

Efferent fibers Afferent fibers Sympathetic fibers Parasympathetic fibers

Parasympathetic root of ciliary ganglion

Mandibular nerve (V3) Internal carotid artery and nerve plexus Maxillary nerve (V2) Lateral rectus muscle and abducent nerve (turned back) Cavernous plexus Common tendinous ring

27

NEUROANATOMY Efferent fibers Afferent fibers Proprioceptive fibers Parasympathetic fibers Sympathetic fibers

Trigeminal Nerve (V): Schema

Ophthalmic nerve (V1)

Tentorial (meningeal) branch Nasociliary nerve Lacrimal nerve Sensory root of ciliary ganglion Frontal nerve Ciliary ganglion Posterior ethmoidal nerve Long ciliary nerve Short ciliary nerves Anterior ethmoidal nerve Supraorbital nerve Supratrochlear nerve Infratrochlear nerve Internal nasal branches and External nasal branches of anterior ethmoidal nerve

Trigeminal nerve (V) ganglion and nuclei Motor nucleus Mesencephalic nucleus Principal sensory nucleus Spinal tract and nucleus

Maxillary nerve (V2) Meningeal branch Zygomaticotemporal nerve Zygomaticofacial nerve Zygomatic nerve Infraorbital nerve Pterygopalatine ganglion Superior alveolar branches of infraorbital nerve Nasal branches (posterior superior lateral, nasopalatine and posterior superior medial)

Facial nerve (VII) Chorda tympani nerve

Nerve (vidian) of pterygoid canal (from facial nerve [VII] and carotid plexus) Pharyngeal branch Greater and lesser palatine nerves Deep temporal nerves (to temporalis muscle) Lateral pterygoid and masseteric nerves Tensor veli palatini and medial pterygoid nerves Buccal nerve Mental nerve Inferior dental plexus Lingual nerve

28

Superficial temporal branches Articular branch and anterior auricular nerves Auriculotemporal nerve Submandibular ganglion Mylohyoid nerve

Inferior alveolar nerve Otic ganglion

Mandibular nerve (V3) Tensor tympani nerve

Parotid branches Meningeal branch Lesser petrosal nerve (from glossopharyngeal nerve [IX])

NEUROANATOMY

Facial Nerve (VII): Schema

Facial nerve (VII)

Greater petrosal nerve

Internal acoustic meatus

Geniculate ganglion

Deep petrosal nerve (from internal carotid plexus)

Intermediate nerve Motor nucleus of facial nerve

Internal carotid plexus (on internal carotid artery)

Lesser petrosal nerve Nerve (vidian) of pterygoid canal

Superior salivatory nucleus Solitary tract nucleus

Otic ganglion Pterygopalatine ganglion

Facial muscles Frontal belly (frontalis) of occipitofrontalis Orbicularis oculi Corrugator supercilii Zygomaticus major Zygomaticus minor

che Temporal bran

Procerus Levator labii superioris Levator labii superioris alaeque nasi

s

Levator anguli oris Nasalis

Depressor septi nasi Orbicularis oris

Zygomatic bra nch es anterior 2â „3 Taste: tongue of

Buccal branches Occipital branch of posterior auricular nerve

al br

anc

h

Depressor anguli oris

Cer vic

Depressor labii inferioris Mentalis (Risorius) (not shown)

al Margin ular ib d man branch

Buccinator

Occipital belly (occipitalis) of occipitofrontalis muscle

Branches to auricular muscles Posterior auricular nerve Nerve to stapedius muscle Stylomastoid foramen Tympanic plexus

Platysma

Tympanic nerve (Jacobson) (from glossopharyngeal nerve)

Sublingual gland Efferent fibers Afferent fibers Parasympathetic fibers Sympathetic fibers

Submandibular gland Submandibular ganglion Lingual nerve (from trigeminal nerve) Chorda tympani nerve

Glossopharyngeal nerve (IX) Digastric muscle (posterior belly) Stylohyoid muscle Caroticotympanic nerve (from internal carotid plexus)

29

NEUROANATOMY

Vestibulocochlear Nerve (VIII): Schema

Afferent fibers

Facial canal Tympanic cavity Geniculum of facial nerve (site of geniculate ganglion)

Chorda tympani nerve

Greater petrosal nerve

Head of malleus

Cochlear (spiral) ganglion

Incus

Vestibular nerve Cochlear nerve Motor root of facial nerve and intermediate nerve Vestibulocochlear nerve (VIII) Medulla oblongata (cross section)

Ampulla of lateral semicircular duct Internal acoustic meatus

Medial Vestibular nuclei (diagrammatic)

Ampulla of superior semicircular duct

Superior Anterior Inferior

Posterior

Utricle

Cochlear nuclei

Ampulla of posterior semicircular duct

Lateral Inferior cerebellar peduncle (to cerebellum) Vestibular ganglion

Saccule Superior division Inferior division

30

of vestibular nerve

NEUROANATOMY

Glossopharyngeal Nerve (IX): Schema

Spinal tract and spinal nucleus of trigeminal nerve

Efferent fibers Afferent fibers Parasympathetic fibers

Solitary tract nucleus Tympanic nerve (Jacobson) Tympanic cavity and plexus Stylomastoid foramen

Caroticotympanic nerve (from internal carotid plexus)

Nucleus ambiguus Inferior salivatory nucleus Geniculate ganglion of facial nerve

Greater petrosal nerve Deep petrosal nerve Nerve (vidian) of pterygoid canal Lesser petrosal nerve Pterygopalatine ganglion Mandibular nerve (V3) Otic ganglion Auriculotemporal nerve Parotid gland Tubal branch of tympanic plexus Pharyngotympanic (auditory) tube and pharyngeal opening Glossopharyngeal nerve (IX)

Stylopharyngeus muscle (and branch from glossopharyngeal nerve)

Jugular foramen Communication to auricular branch of vagus nerve Superior and Inferior ganglia of Glossopharyngeal nerve Communication to facial nerve (VII) Taste and somatic sensation: posterior 1 â „3 of tongue

Vagus nerve (X) Superior cervical sympathetic ganglion Sympathetic trunk Carotid branch of glossopharyngeal nerve Internal carotid artery

Pharyngeal plexus Carotid sinus Pharyngeal, tonsillar and lingual branches of glossopharyngeal nerve

Carotid body Common carotid artery

Pharyngeal branch of vagus nerve External carotid artery

31

NEUROANATOMY SEE ALSO PLATE 160

Vagus Nerve (X): Schema Posterior nucleus of vagus nerve (parasympathetic and visceral afferent)

Glossopharyngeal nerve (IX)

Solitary tract nucleus (visceral afferents including taste)

Meningeal branch of vagus nerve Auricular branch of vagus nerve

Spinal tract and spinal nucleus of trigeminal nerve (somatic afferent)

Pharyngotympanic (auditory) tube Levator veli palatini muscle

Nucleus ambiguus (motor to pharyngeal and laryngeal muscles)

Salpingopharyngeus muscle

Cranial root of accessory nerve* (see next plate)

Palatoglossus muscle

Vagus nerve (X)

Palatopharyngeus muscle

Jugular foramen

Superior pharyngeal constrictor muscle

Superior ganglion of vagus nerve Inferior ganglion of vagus nerve

Stylopharyngeus muscle Middle pharyngeal constrictor muscle

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

Inferior pharyngeal constrictor muscle Cricothyroid muscle Trachea Esophagus Right subclavian artery Right recurrent laryngeal nerve Heart Hepatic branch of anterior vagal trunk (in lesser omentum) Celiac branches from anterior and posterior vagal trunks to celiac plexus Celiac and superior mesenteric ganglia and celiac plexus Hepatic plexus Gallbladder and bile ducts Liver Pyloric branch from hepatic plexus Pancreas Duodenum Ascending colon Cecum Appendix

32

Communicating branch of vagus nerve to carotid branch of glossopharyngeal nerve Pharyngeal plexus Superior laryngeal nerve: Internal branch (sensory and parasympathetic) External branch (motor to cricothyroid muscle) Superior cervical cardiac branch of vagus nerve Inferior cervical cardiac branch of vagus nerve Thoracic cardiac branch of vagus nerve Left recurrent laryngeal nerve (motor to muscles of larynx except cricothyroid; sensory and parasympathetic to larynx below vocal folds; parasympathetic, efferent and afferent to upper esophagus and trachea) Pulmonary plexus Cardiac plexus Esophageal plexus Anterior vagal trunk Gastric branches of anterior vagal trunk (branches from posterior trunk behind stomach) Vagal branches (parasympathetic motor, secretomotor and afferent fibers) accompany superior mesenteric artery and its branches usually as far as left colic (splenic) flexure Small intestine Efferent fibers Afferent fibers Parasympathetic fibers

NEUROANATOMY

Accessory Nerve (XI): Schema

SEE ALSO PLATE 28 Nucleus ambiguus Vagus nerve (X)

Cranial root of accessory nerve (joins vagus nerve and via recurrent laryngeal nerve supplies muscles of larynx, except cricothyroid)* Spinal root of accessory nerve Foramen magnum

Jugular foramen Superior ganglion of vagus nerve Accessory nerve (XI)*

Inferior ganglion of vagus nerve

C1 spinal nerve C2 spinal nerve Accessory nerve (to sternocleidomastoid and 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.

33

NEUROANATOMY

Hypoglossal Nerve (XII): Schema

Hypoglossal nerve (XII) (in hypoglossal canal)

Hypoglossal nucleus

Superior longitudinal Intrinsic muscles of tongue

Transverse and vertical Inferior longitudinal

Meningeal branch

Styloglossus muscle

Occipital condyle Inferior ganglion of vagus nerve Ventral rami of C1, 2, 3 form ansa cervicalis of cervical plexus Superior cervical sympathetic ganglion Superior root of ansa cervicalis

Genioglossus muscle

Internal carotid artery

Geniohyoid muscle Hyoglossus muscle Thyrohyoid muscle Omohyoid muscle (superior belly) Sternohyoid muscle

Inferior root of ansa cervicalis Ansa cervicalis Internal jugular vein Common carotid artery

Sternothyroid muscle Omohyoid muscle (inferior belly)

Efferent fibers Afferent fibers

34

NEUROANATOMY

Nerves of Heart

Superior cervical sympathetic ganglion Vagus nerve (X) (Conjoined sympathetic and vagal) superior cervical cardiac nerves Middle cervical sympathetic ganglion Middle cervical (sympathetic) cardiac nerve Phrenic nerve Inferior cervical (vagal) cardiac nerve Vertebral ganglion Inferior thyroid artery Vertebral artery Cervicothoracic (stellate) ganglion Ansa subclavia

Superior cervical sympathetic ganglion Vagus nerve (X) Superior cervical (sympathetic) cardiac nerve Superior cervical (vagal) cardiac nerve Middle cervical sympathetic ganglion Phrenic nerve Middle cervical (sympathetic) cardiac nerve Inferior cervical (vagal) cardiac nerve Vertebral ganglion Cervicothoracic (stellate) ganglion Inferior cervical sympathetic cardiac nerves

Recurrent laryngeal nerve

Inferior cervical (sympathetic) cardiac nerves Thoracic cardiac branch of vagus nerve 4th thoracic sympathetic ganglion Thoracic (sympathetic) cardiac branches Cardiac plexus

3rd thoracic sympathetic ganglion Thoracic (sympathetic) cardiac branches Thoracic cardiac branch of vagus nerve Recurrent laryngeal nerve

Phrenic nerve (cut)

35

NEUROANATOMY

Right sympathetic trunk Thoracic duct

Autonomic Nerves and Ganglia of Abdomen

Anterior, Posterior vagal trunks

Right greater and lesser splanchnic nerves

Left gastric artery and plexus

Right phrenic nerve

Left greater splanchnic nerve

Inferior phrenic arteries and plexuses

Left lesser splanchnic nerve

Right greater and lesser splanchnic nerves

Splenic artery and plexus

Right suprarenal plexus

Celiac ganglia

Common hepatic artery and plexus Superior mesenteric ganglion and plexus

Right aorticorenal ganglion

Left aorticorenal ganglion

Right least splanchnic nerve

Left sympathetic trunk

Right renal artery and plexus

Intermesenteric (aortic) plexus

Right sympathetic trunk

Inferior mesenteric ganglion

White and gray rami communicantes

Left colic artery and plexus

Cisterna chyli

Inferior mesenteric artery and plexus

Gray ramus communicans 3rd lumbar ganglion of sympathetic trunk 2nd and 3rd lumbar splanchnic nerves Right ureter and plexus Right testicular (ovarian) artery and plexus 4th lumbar splanchnic nerve 1st sacral ganglion of sympathetic trunk Gray rami communicantes

Left common iliac artery and plexus Superior rectal artery and plexus Superior hypogastric plexus Internal and external iliac arteries and plexuses Right and left hypogastric nerves to inferior hypogastric (pelvic) plexus Left sacral plexus Pelvic splanchnic nerves

36

NEUROANATOMY

Nerves of Stomach and Duodenum

Right and left inferior phrenic arteries and plexuses Anterior and posterior layers of lesser omentum Branch from hepatic plexus to cardia via lesser omentum Right greater splanchnic nerve

Hepatic branch of anterior vagal trunk Anterior vagal trunk Celiac branch of posterior vagal trunk Celiac branch of anterior vagal trunk Left gastric artery and plexus

Vagal branch from hepatic plexus to pyloric part of stomach Hepatic plexus Right gastric artery and plexus

Anterior gastric branch of anterior vagal trunk Left greater splanchnic nerve Left lesser splanchnic nerve Splenic artery and plexus Celiac ganglia and plexus Plexus on gastro-omental (gastroepiploic) arteries Superior mesenteric artery and plexus Plexus on inferior pancreaticoduodenal artery Plexus on first jejunal artery Plexus on anterior superior and anterior inferior pancreaticoduodenal arteries (posterior pancreaticoduodenal arteries and plexuses not visible in this view)

37

NEUROANATOMY

Nerves of Stomach and Duodenum (continued)

Posterior gastric branch of posterior vagal trunk

Plexus on gastro-omental (gastroepiploic) arteries

Hepatic branch of anterior vagal trunk via lesser omentum

Hepatic plexus

Branch from hepatic plexus to cardia via lesser omentum

Right gastric artery and plexus

Right inferior phrenic artery and plexus Posterior vagal trunk Celiac branch of posterior vagal trunk Celiac branch of anterior vagal trunk Left gastric artery and plexus Left inferior phrenic artery and plexus Celiac ganglia and plexus Greater, lesser and least splanchnic nerves Aorticorenal ganglia Splenic artery and plexus

Right phrenic nerve Phrenic ganglion

Greater, Lesser, Least splanchnic nerves

Branch from right inferior phrenic plexus to cardia of stomach Right and left inferior phrenic arteries and plexuses Anterior vagal trunk Posterior vagal trunk

View with stomach reflected cephalad

Plexus on anterior superior and anterior inferior pancreaticoduodenal arteries

Right greater, lesser and least splanchnic nerves

Plexus on gastroduodenal artery Plexus on posterior superior and posterior inferior pancreaticoduodenal arteries

Celiac ganglia

Superior mesenteric ganglion and plexus

Right aorticorenal ganglion

Superior mesenteric ganglion and plexus

38

Celiac branches of anterior and posterior vagal trunks Left gastric artery and plexus Left greater, lesser and least splanchnic nerves Left aorticorenal ganglion

Nerves of Small Intestine

NEUROANATOMY

Recurrent branch of left inferior phrenic artery and plexus to esophagus Anterior vagal trunk Posterior vagal trunk Hepatic branch of anterior vagal trunk (courses in lesser omentum, removed here) Celiac branches of anterior and posterior vagal trunks Inferior phrenic arteries and plexuses Left gastric artery and plexus Hepatic plexus Greater splanchnic nerves Right gastric artery and plexus (cut) Celiac ganglia and plexus Gastroduodenal artery and plexus Lesser splanchnic nerves Least splanchnic nerves Aorticorenal ganglia Superior mesenteric ganglion Intermesenteric (aortic) plexus Inferior pancreaticoduodenal arteries and plexuses Superior mesenteric artery and plexus Middle colic artery and plexus (cut) Right colic artery and plexus Ileocolic artery and plexus Superior mesenteric artery and plexus Peritoneum (cut edge) Mesenteric branches Mesoappendix (contains appendicular artery and nerve plexus)

39

NEUROANATOMY

Nerves of Large Intestine

Anterior vagal trunk and hepatic branch Posterior vagal trunk Celiac branches of anterior and posterior vagal trunks Right inferior phrenic artery and plexus Right greater splanchnic nerve

Marginal artery and plexus Esophagus Left inferior phrenic artery and plexus Left gastric artery and plexus Left greater splanchnic nerve

Celiac ganglia and plexus

Left suprarenal plexus

Right lesser and least splanchnic nerves

Left lesser and least splanchnic nerves

Right aorticorenal ganglion

Left aorticorenal ganglion

Superior mesenteric ganglion

Left renal artery and plexus

Middle colic artery and plexus

1st left lumbar splanchnic nerve

Inferior pancreaticoduodenal arteries and plexuses

Left lumbar sympathetic trunk

Right colic artery and plexus

Left colic artery and plexus

Intermesenteric (aortic) plexus

Inferior mesenteric ganglion, artery and plexus

Ileocolic artery and plexus

Sigmoid arteries and plexuses

Cecal and appendicular arteries and plexuses

Superior hypogastric plexus

Right internal iliac artery and plexus (cut)

Superior rectal artery and plexus

Sacral sympathetic trunk Right sacral plexus

Right and left hypogastric nerves

Pelvic splanchnic nerves Middle rectal artery and plexus Right inferior hypogastric (pelvic) plexus Vesical plexus Rectal plexus Urinary bladder

40

Rectosigmoid artery and plexus Nerves from inferior hypogastric (pelvic) plexuses to sigmoid colon, descending colon and left colic (splenic) flexure

Nerves of Kidneys, Ureters and Urinary Bladder

NEUROANATOMY

Anterior vagal trunk Posterior vagal trunk Greater splanchnic nerve Celiac ganglia and plexus Lesser splanchnic nerve Superior mesenteric ganglion Least splanchnic nerve Aorticorenal ganglion Renal plexus and ganglion 2nd lumbar splanchnic nerve Renal and upper ureteric branches from intermesenteric plexus Intermesenteric (aortic) plexus Testicular (ovarian) artery and plexus Inferior mesenteric ganglion Sympathetic trunk and ganglion Middle ureteric branch Superior hypogastric plexus Sacral splanchnic nerves (branches from upper sacral sympathetic ganglia to hypogastric plexus) Gray ramus communicans Hypogastric nerves Sacral plexus Pudendal nerve Pelvic splanchnic nerves Inferior hypogastric (pelvic) plexus with periureteric loops and branches to lower ureter Rectal plexus Vesical plexus Prostatic plexus

41

NEUROANATOMY

Anterior vagal trunk

Nerves of Pelvic Viscera: Male

T10 spinal nerve (anterior ramus)

Posterior vagal trunk and Celiac branch

White and gray rami communicantes Greater Lesser Least

Inferior phrenic arteries and plexuses Left gastric artery and gastric plexus

Diaphragm

Celiac ganglia, plexus and trunk

Left renal artery and plexus

Left aorticorenal ganglion

L1 spinal nerve (anterior ramus)

Superior mesenteric ganglion Superior mesenteric artery and plexus

Gray White

Intermesenteric (aortic) plexus Inferior mesenteric ganglion, artery and plexus

Splanchnic nerves

Rami communicantes

1st, 2nd, 3rd lumbar splanchnic nerves Gray rami communicantes

Ureter and ureteric plexus Sympathetic trunk and ganglia Superior hypogastric plexus Superior rectal artery and plexus Hypogastric nerves

5th lumbar splanchnic nerve L5 spinal nerve (anterior ramus) Lumbosacral trunk

Nerve from inferior hypogastric plexus to sigmoid and descending colon (parasympathetic)

Gray rami communicantes S1 spinal nerve (anterior ramus)

Sacral splanchnic nerves (sympathetic)

Pelvic splanchnic nerves (parasympathetic)

Inferior hypogastric (pelvic) plexus

Sacral plexus

Obturator nerve and artery

Piriformis muscle

Ductus deferens and plexus

Gluteus maximus muscle and sacro tuberous ligament

Vesical plexus Rectal plexus

(Ischio-)coccygeus muscle and sacrospinous ligament

Prostatic plexus Cavernous nerves of penis

Pudendal nerve Levator ani muscle Inferior anal (rectal) nerve Perineal nerve Dorsal nerve of penis Posterior scrotal nerves

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NEUROANATOMY

Nerves of Pelvic Viscera: Female

Peritoneum

Abdominal aorta

Sympathetic trunk and L2 ganglion

Inferior vena cava Extraperitoneal (subserous) fascia

White and gray rami communicantes

Common iliac vessels and plexus

Lumbar splanchnic nerves

Ureter Intermesenteric (aortic) plexus Ovarian artery and plexus

Gray rami communicantes

Superior hypogastric plexus

L5 spinal nerve

Sacral promontory Superior hypogastric plexus

Right hypogastric nerve (cut)

Common iliac artery and plexus

Right and left sacral sympathetic trunks and ganglia

Ureter Internal iliac artery and plexus

S1

Piriformis muscle

S2

Sigmoid colon

External iliac artery and plexus

Right and left hypogastric nerves Uterus Right sympathetic trunk

S3

Sacral splanchnic nerves (sympathetic)

S4 S5

Pudendal nerve

Left hypogastric nerve Inferior hypogastric (pelvic) plexus Uterine (fallopian) tube Ovary

Pelvic splanchnic nerves (parasympathetic)

Symphyseal surface of pubis Urinary bladder Vesical plexus

(Ischio-)coccygeus muscle

Rectal plexus

Uterovaginal plexus Uterus (retracted)

Rectum (retracted)

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NEUROANATOMY

Median Nerve

Anterior view

Note: Only muscles innervated by median nerve shown

Musculocutaneous nerve

Median nerve (C5, 6, 7, 8, T1) Medial Posterior Lateral

Inconstant contribution

Cords of brachial plexus

Pronator teres muscle (humeral head) Medial cutaneous nerve of arm Articular branch Medial cutaneous nerve of forearm Flexor carpi radialis muscle Axillary nerve Palmaris longus muscle

Radial nerve

Pronator teres muscle (ulnar head)

Ulnar nerve

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

Cutaneous innervation

Palmar branch of median nerve

Thenar muscles

Abductor pollicis brevis Opponens pollicis Superficial head of flexor pollicis brevis (deep head supplied by ulnar nerve)

1st and 2nd lumbrical muscles

Palmar view Communicating branch of median nerve with ulnar nerve Common palmar digital nerves Proper palmar digital nerves

Dorsal branches to dorsum of middle and distal phalanges

Posterior (dorsal) view

44

NEUROANATOMY

Ulnar Nerve

Anterior view

Note: Only muscles innervated by ulnar nerve shown Ulnar nerve (C7, 8, T1) (no branches above elbow) Inconstant contribution

Medial epicondyle Articular branch (behind condyle)

Cutaneous innervation

Flexor digitorum profundus muscle (medial part only; lateral part supplied by anterior interosseous branch of median nerve)

Palmar view

Flexor carpi ulnaris muscle (drawn aside)

Dorsal branch of ulnar nerve

Posterior (dorsal) view

Flexor pollicis brevis muscle (deep head only; superficial head and other thenar muscles supplied by median nerve)

Adductor pollicis muscle

Palmar branch

Superficial branch Deep branch Palmaris brevis Abductor digiti minimi Flexor digiti minimi brevis Opponens digiti minimi

Hypothenar muscles

Common palmar digital nerve Communicating branch of median nerve with ulnar nerve Palmar and dorsal interosseous muscles 3rd and 4th lumbrical muscles (turned down) Proper palmar digital nerves (dorsal digital nerves are from dorsal branch) Dorsal branches to dorsum of middle and distal phalanges

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NEUROANATOMY

Radial Nerve in Arm and Nerves of Posterior Shoulder

Dorsal scapular nerve (C5)

Posterior view

Supraspinatus muscle Suprascapular nerve (C5, 6) Levator scapulae muscle (supplied also by branches from C3 and C4)

Deltoid muscle Teres minor muscle Axillary nerve (C5, 6) Superior lateral cutaneous nerve of arm

Rhomboid minor muscle

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

Rhomboid major muscle

Inferior lateral cutaneous nerve of arm

Posterior cutaneous nerve of forearm Infraspinatus muscle Teres major muscle Lower subscapular nerve (C5, 6) Posterior cutaneous nerve of arm (branch of radial nerve in axilla) Long head Triceps brachii muscle

Lateral intermuscular septum

Brachialis muscle (lateral part; remainder of muscle supplied by musculocutaneous nerve)

Lateral head Medial head Brachioradialis muscle Triceps brachii tendon Medial epicondyle

Extensor carpi radialis longus muscle

Olecranon Anconeus muscle Extensor digitorum muscle Extensor carpi ulnaris muscle

46

Extensor carpi radialis brevis muscle

NEUROANATOMY

Radial Nerve in Forearm

Inconstant contribution

Radial nerve (C5, 6, 7, 8, T1) Superficial (terminal) branch Deep (terminal) branch

Posterior view

Lateral epicondyle Anconeus muscle Brachioradialis muscle Extensor carpi radialis longus muscle Supinator muscle Extensor carpi radialis brevis muscle Extensor carpi ulnaris muscle

Extensor- supinator group of muscles

Extensor digitorum muscle and extensor 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 nerve

Superior lateral cutaneous nerve of arm

Inferior lateral cutaneous nerve of arm Posterior cutaneous nerve of arm From radial nerve Posterior cutaneous nerve of forearm Superficial branch of radial nerve and dorsal digital branches

Dorsal digital nerves Cutaneous innervation from radial and axillary nerves

47

NEUROANATOMY

Sciatic Nerve and Posterior Cutaneous Nerve of Thigh

Posterior cutaneous nerve of thigh (S1, 2, 3) Greater sciatic foramen Inferior cluneal nerves Sciatic nerve (L4, 5, S1, 2, 3) Perineal branches Common fibular (peroneal) division of sciatic nerve

Tibial division of sciatic nerve Long head (cut) of biceps femoris muscle

Short head of biceps femoris muscle

Adductor magnus muscle (also partially supplied by obturator nerve)

Cutaneous innervation

Long head (cut) of biceps femoris muscle

Semitendinosus muscle Semimembranosus muscle Tibial nerve

Common fibular (peroneal) nerve

Articular branch

Posterior cutaneous nerve of thigh

Articular branch Plantaris muscle Medial sural cutaneous nerve

Lateral sural cutaneous nerve

Sural communicating branch

Gastrocnemius muscle

Common fibular (peroneal) nerve via lateral sural cutaneous nerve

Sural nerve Medial sural cutaneous nerve Soleus muscle

From sciatic nerve

Tibial nerve Medial calcaneal branches Medial and lateral plantar nerves

48

Superficial fibular (peroneal) nerve Sural nerve

Lateral calcaneal branches

Lateral dorsal cutaneous nerve

Tibial nerve via medial calcaneal branches

NEUROANATOMY

Tibial Nerve

Common fibular (peroneal) nerve Tibial nerve (L4, 5, S1, 2, 3)

Articular branch Lateral sural cutaneous nerve (cut)

Medial sural cutaneous nerve (cut)

Medial calcaneal branches (S1, 2)

Articular branches

Medial plantar nerve (L4, 5)

From tibial nerve

Plantaris muscle

Lateral plantar nerve (S1, 2)

Gastrocnemius muscle (cut)

Saphenous nerve (L3, 4) Sural nerve (S1, 2) via lateral calcaneal and lateral dorsal cutaneous branches

Nerve to popliteus muscle

Popliteus muscle

Cutaneous innervation of sole

Interosseous nerve of leg

Soleus muscle (cut and partly retracted)

Flexor digitorum longus muscle

Tibialis posterior muscle

Flexor hallucis longus muscle

Sural nerve (cut)

Lateral calcaneal branch

Medial calcaneal branch

Flexor retinaculum (cut)

Flexor retinaculum (cut) Tibial nerve Medial calcaneal branch Medial plantar nerve Flexor digitorum brevis muscle and nerve Abductor hallucis muscle and nerve Flexor hallucis brevis muscle and nerve 1st lumbrical muscle and nerve Common plantar digital nerves Proper plantar digital nerves

Lateral calcaneal branch of sural nerve Lateral plantar nerve Nerve to abductor digiti minimi muscle Quadratus plantae muscle and nerve Abductor digiti minimi muscle Deep branch to interosseous muscles, 2nd, 3rd and 4th lumbrical muscles and Adductor hallucis muscle Superficial branch to 4th interosseous muscle and Flexor digiti minimi brevis muscle Common and Proper plantar digital nerves

Lateral dorsal cutaneous nerve Note: Articular branches not shown

49

NEUROANATOMY

Common fibular (peroneal) nerve (phantom)

Common Fibular (Peroneal) Nerve

Lateral sural cutaneous nerve (phantom)

Articular branches Biceps femoris tendon Recurrent articular nerve Common fibular (peroneal) nerve (L4, 5, S1, 2)

Extensor digitorum longus muscle (cut)

Head of fibula Deep fibular (peroneal) nerve Fibularis (peroneus) longus muscle (cut)

Tibialis anterior muscle

Cutaneous innervation

Superficial fibular (peroneal) nerve

Branches of lateral sural cutaneous nerve

Fibularis (peroneus) longus muscle

Extensor digitorum longus muscle

Extensor hallucis longus muscle

Fibularis (peroneus) brevis muscle Lateral sural cutaneous nerve

Medial dorsal cutaneous nerve

Intermediate dorsal cutaneous nerve

Inferior extensor retinaculum (partially cut)

Lateral dorsal cutaneous nerve (branch of sural nerve)

Dorsal digital nerves

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Superficial fibular (peroneal) nerve Lateral branch of deep fibular (peroneal) nerve to Extensor hallucis brevis and Extensor digitorum brevis muscles Medial branch of deep fibular (peroneal) nerve

Deep fibular (peroneal) nerve

Sural nerve via lateral dorsal cutaneous branch

Click any title below to link to that plate.

Part 2 Neurophysiology Organization of the Brain: Cerebrum. . . . . . . 52

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

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

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

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

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

Synaptic Transmission: Morphology of Synapses . . . . . . . . . . . . . . . 55

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

Synaptic Transmission: Neuromuscular Junction . . . . . . . . . . . . . . . 56 Synaptic Transmission: Visceral Efferent Endings . . . . . . . . . . . . . . . 57

Cutaneous Sensory Receptors . . . . . . . . . . . . . 74 Cutaneous Receptors: Pacinian Corpuscle. . . . . . . . . . . . . . . . . . . . 75 Proprioception and Reflex Pathways: I . . . . . . 76

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

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

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

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

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

Proprioception and Reflex Pathways: III . . . . 78

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

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

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

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

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

NEUROPHYSIOLOGY

Organization of the Brain: Cerebrum

Postcentral gyrus

Central sulcus (Rolando) Precentral gyrus

Postcentral sulcus

Precentral sulcus

Superior parietal lobule Inferior parietal lobule Supramarginal gyrus Angular gyrus

Parietooccipital sulcus

Occipital pole Frontal pole Calcarine sulcus

Lateral sulcus (Sylvius) Temporal pole

Superior temporal gyrus

Inferior temporal gyrus

Middle temporal gyrus Frontal lobe Parietal lobe

Temporal lobe Occipital lobe

Insula (island of Reil) Š

FIGURE 2.1 ORGANIZATION

OF THE

BRAIN: CEREBRUM•

The cerebral cortex represents the highest center for sensory and motor processing. In general, the frontal lobe processes motor, visual, speech, and personality modalities. The parietal lobe processes sensory information; the temporal lobe, auditory and memory modalities; and the occipital lobe, vision. The cerebellum

52

coordinates smooth motor activities and processes muscle position.

The brainstem (medulla, pons, midbrain) conveys motor and sensory information and mediates important autonomic functions. The spinal cord receives sensory input from the body and conveys somatic and autonomic motor information to peripheral targets (muscles, viscera).

NEUROPHYSIOLOGY

Organization of the Brain: Cell Types

Bipolar cell of cranial n.

Multipolar (pyramidal) cell of cerebral motor cortex

Unipolar cell of sensory ganglia of cranial nn.

Satellite cells Schwann cell

Astrocyte Interneurons Blood vessel

Striated (somatic) muscle Motor endplate Multipolar somatic motor cell of nuclei of cranial nn.

Multipolar cell of lower brain motor centers

Specialized ending Muscle spindle Unipolar sensory cell of dorsal spinal root ganglion Satellite cells

Interneuron

Oligodendrocyte

Astrocyte

Corticospinal (pyramidal) fiber

Myelinated afferent fiber of spinal nerve

Multipolar visceral motor (autonomic) cell of spinal cord

Axodendritic ending Axosomatic ending

Myelin sheath

Axoaxonic ending Multipolar somatic motor cell of anterior horn of spinal cord

Autonomic preganglionic (sympathetic or parasympathetic) nerve fiber Myelin sheath Autonomic postganglionic neuron of sympathetic or parasympathetic ganglion Satellite cells Unmyelinated nerve fiber Schwann cells

Collateral Renshaw interneuron (feedback) Myelinated somatic motor fiber of spinal nerve Myelin sheath

Red: Blue: Purple: Gray:

Motor neuron Sensory neuron Interneuron Glial and neurilemmal cells and myelin

Note: Cerebellar cells not shown here

Schwann cells

Motor endplate with Schwann cell cap

Endings on cardiac muscle or nodal cells

Striated (voluntary) muscle

FIGURE 2.2 ORGANIZATION

Free nerve endings (unmyelinated fibers) Encapsulated ending

Unmyelinated fibers Free nerve endings

Beaded varicosities and endings on smooth muscle and gland cells

OF THE

Encapsulated ending Muscle spindle

Š

BRAIN: CELL TYPES•

Neurons form the functional cellular units responsible for communication, and throughout the nervous system, they are characterized by their distinctive size and shapes (e.g., bipolar, unipolar, multipolar). Supporting cells include the neuroglia

(e.g., astrocytes, oligodendrocytes), satellite cells, and other specialized cells that optimize neuronal function, provide maintenance functions, or protect the nervous system.

53

NEUROPHYSIOLOGY

Blood-Brain Barrier

Cell membrane Basement membrane

Tight junction proteins

Cytoplasm

Red blood cell Astrocyte foot processes

Capillary lumen

Tight junction

Capillary endothelial cell

Astrocyte ©

FIGURE 2.3 BLOOD-BRAIN BARRIER• The blood-brain barrier (BBB) is the cellular interface between the blood and the central nervous system (CNS; brain and spinal cord).

It serves to maintain the interstitial fluid environment to ensure optimal functionality of the neurons. This barrier consists of the capillary endothelial cells with an elaborate network of tight junctions and astrocytic foot processes that abut the endothelium and its basement membrane. The movement of large molecules and

54

other substances (including many drugs) from the blood to the interstitial space of the CNS is restricted by the BBB. CNS endothelial cells also exhibit a low level of pinocytotic activity across the cell, so specific carrier systems for the transport of essential substrates of energy and amino acid metabolism are characteristic of these cells. The astrocytes help transfer important metabolites from the blood to the neurons and also remove excess K⫹ and neurotransmitters from the interstitial fluid.

NEUROPHYSIOLOGY

Synaptic Transmission: Morphology of Synapses

Dendrite Node

Dendrites

Axon

Myelin sheath

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

Enlarged section of bouton

Axon (axoplasm) Axolemma Mitochondria Glial process Synaptic vesicles Synaptic cleft Presynaptic membrane (densely staining) Postsynaptic membrane (densely staining) Postsynaptic cell

©

FIGURE 2.4 MORPHOLOGY OF SYNAPSES• Neurons communicate with each other and with effector targets at specialized regions called synapses. The top figure shows a typical motor neuron that receives numerous synaptic contacts on its cell body and associated dendrites. Incoming axons lose their myelin sheaths, exhibit extensive branching, and terminate as synaptic boutons (synaptic terminals or knobs) on the motor neuron. The

lower figure shows an enlargement of one such synaptic bouton.

Chemical neurotransmitters are contained in synaptic vesicles, which can fuse with the presynaptic membrane, release the transmitters into the synaptic cleft, and then bind to receptors situated in the postsynaptic membrane. This synaptic transmission results in excitatory, inhibitory, or modulatory effects on the target cell.

55

NEUROPHYSIOLOGY

Synaptic Transmission: Neuromuscular Junction

Structure of Neuromuscular Junction

Active zone

Myelin sheath Neurilemma

Schwann cell process

Axoplasm Acetylcholine receptor sites

Schwann cell Mitochondria Basement membrane Nucleus of Schwann cell Presynaptic membrane Active zone Synaptic vesicles Synaptic trough Basement membrane Sarcolemma Nucleus of muscle cell

Myofibrils Synaptic cleft Postsynaptic membrane Junctional fold Sarcoplasm Acetylcholine receptor sites

©

FIGURE 2.5 STRUCTURE

OF THE

NEUROMUSCULAR JUNCTION•

Motor axons that synapse on skeletal muscle form expanded terminals called neuromuscular junctions (motor endplates). The motor axon loses its myelin sheath and expands into a Schwann cell–invested synaptic terminal that resides within a trough in the muscle fiber. Acetylcholine-containing synaptic vesicles accumulate adjacent to the presynaptic membrane and, when appropri-

56

ately stimulated, release their neurotransmitter into the synaptic cleft. The transmitter then binds to receptors that mediate depolarization of the muscle sarcolemma and initiate a muscle action potential. A single muscle fiber has only one neuromuscular junction, but a motor axon can innervate multiple muscle fibers.

NEUROPHYSIOLOGY

Synaptic Transmission: Visceral Efferent Endings

Visceral Efferent Endings B. Gland (submandibular)

      

      

       A. Smooth muscle

C. Neurosecretory (posterior pituitary)

Sympathetic terminal ending Smooth muscle cells (cut) Schwann cell cap enclosing nerve axons

Mucous cells Schwann cell cap enclosing nerve axons

Varicosity

Pituicyte processes Axon

Axon

Schwann cell cap

Fibroblast

Schwann cell cap Serous cells

Smooth muscle cells Varicosities Terminal endings

Parasympathetic terminal ending

Schwann cell cap enclosing nerve axons

Capillary Endothelium Mast cell

Varicosity

Neurosecretory vesicles Collagen space Basement membrane

©

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

rosecretion) from expanded nerve terminal endings. This arrangement allows for the stimulation of numerous target cells over a wide area. Not all smooth muscle cells are innervated. They are connected to adjacent cells by gap junctions and can therefore contract together with the innervated cells.

57

NEUROPHYSIOLOGY

Synaptic Transmission: Inhibitory Mechanisms

I (Inhibitory fiber)

E (Excitatory fiber)

Motor neuron

E (Excitatory fiber)

Motor neuron

I (Inhibitory fiber)

Axon

mV ⫹20 A. Only E fires 90-mV spike in E terminal

EPSP in motor neuron B. Only I fires Long-lasting partial depolarization in E terminal No response in motor neuron C. I fires before E Partial depolarization of E terminal reduces spike to 80 mV, thus releasing less transmitter substance Smaller EPSP in motor neuron

Axon

mV 90 mV

A′. Only E fires EPSP in motor neuron

⫺70 ⫺60 ⫺70

⫺60 ⫺70

B′. Only I fires Motor neuron hyperpolarized

⫺60 ⫺70 ⫺70

⫺70 ⫺80

C′. I fires before E ⫹20 80 mV

Depolarization of motor neuron less than if only E fires

⫺60 ⫺70 ⫺80

⫺70 ⫺60 ⫺70

©

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

58

NEUROPHYSIOLOGY

Synaptic Transmission: Chemical Synaptic Transmission

              Inhibitory

Excitatory

Synaptic vesicles in synaptic bouton Presynaptic membrane

Na

K

Transmitter substances

Synaptic cleft Postsynaptic membrane

When impulse reaches excitatory synaptic bouton, it causes release of a transmitter substance into synaptic cleft. This increases permeability of postsynaptic membrane to Na and K . More Na moves into postsynaptic cell than K moves out, due to greater electrochemical gradient

Cl

At inhibitory synapse, transmitter substance released by an impulse increases permeability of the postsynaptic membrane to Cl . K moves out of post-synaptic cell but no net flow of Cl occurs at resting membrane potential

Synaptic bouton

Potential (mV)

Current 65

70

Potential

0

Resultant ionic current flow is in direction that tends to hyperpolarize postsynaptic cell. This makes depolarization by excitatory synapses more difficult—more depolarization is required to reach threshold msec 0 4 8 12 16 70 Potential (mV)

Resultant net ionic current flow is in a direction that tends to depolarize postsynaptic cell.

If depolarization reaches firing threshold, an impulse is generated in postsynaptic cell

8 12 16 msec Current flow and potential change

Potential 75

Current

4

Current flow and potential change

©

FIGURE 2.8 CHEMICAL SYNAPTIC TRANSMISSION• Chemical synaptic transmission between neurons may be excitatory or inhibitory. During excitation (left column), a net increase in the inward flow of Na compared with the outward flow of K results in a depolarizing potential change (excitatory postsynaptic potential [EPSP]) that drives the postsynaptic cell closer to its

threshold for an action potential. During inhibition (right column), the opening of K and Cl channels drives the membrane potential away from threshold (hyperpolarization) and decreases the probability that the neuron will reach threshold (inhibitory postsynaptic potential [IPSP]) for an action potential.

59

NEUROPHYSIOLOGY

Synaptic Transmission: Temporal and Spatial Summation

Temporal and Spatial Summation of Excitation and Inhibition Excitatory fibers

mV

mV

Excitatory fibers

–70

–70

Axon

Axon Inhibitory 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

mV

Excitatory fibers

mV

Excitatory fibers

–70

–70

Axon

Axon Inhibitory fibers

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

mV

Excitatory fibers

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

mV

Excitatory fibers

–70

–70

Axon

Axon

Inhibitory fibers

Inhibitory fibers

E. Spatial excitatory summation with inhibition: impulses from two excitatory fibers reach motor neuron but impulses from inhibitory fiber prevent depolarization from reaching threshold

E. (continued): motor neuron now receives additional excitatory impulses and reaches firing threshold despite a simultaneous inhibitory impulse; additional inhibitory impulses might still prevent firing

©

CHART 2.1 SUMMARY OF SOME NEUROTRANSMITTERS AND WHERE WITHIN THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM THEY ARE FOUND Transmitter Acetylcholine Biogenic amines Norepinephrine Dopamine Serotonin Amino acids ␥-Aminobutyric acid (GABA) Glutamate Purines Adenosine Adenosine triphosphate (ATP)

Location Neuromuscular junction, autonomic endings and ganglia, CNS Sympathetic endings, CNS CNS CNS, GI tract CNS CNS CNS CNS

Transmitter Gas Nitric oxide Peptides ␤-Endorphins Enkephalins Antidiuretic hormone Pituitary-releasing hormones Somatostatin Neuropeptide Y Vasoactive intestinal peptide

Location CNS, GI tract CNS, GI tract CNS CNS (hypothalamus/posterior pituitary) CNS (hypothalamus/anterior pituitary) CNS, GI tract CNS CNS, GI tract

CNS, Central nervous system; GI, gastrointestinal.

FIGURE 2.9 TEMPORAL

AND

SPATIAL SUMMATION •

Neurons receive multiple excitatory and inhibitory inputs. Temporal summation occurs when a series of subthreshold impulses in one excitatory fiber produces an action potential in the postsynaptic cell (panel C). Spatial summation occurs when subthreshold impulses from two or more different fibers trigger an action poten-

60

tial (panel D). Both temporal and spatial summation can be modulated by simultaneous inhibitory input (panel E). Inhibitory and excitatory neurons use a wide variety of neurotransmitters, some of which are summarized here.

Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition

NEUROPHYSIOLOGY

Left lateral phantom view Frontal (anterior) horn

Right lateral ventricle

Central part Temporal (inferior) horn

Left lateral ventricle

Occipital (posterior) horn

Cerebral aqueduct (Sylvius) 4th ventricle Left lateral aperture (foramen of Luschka) Left lateral recess Left interventricular foramen (Monro)

Median aperture (foramen of Magendie)

3rd ventricle

Central canal of spinal cord

©

CHART 2.2 CSF COMPOSITION

Na⫹ (mEq/L) K⫹ (mEq/L) Cl− (mEq/L) HCO3− (mEq/L) Glucose (mg/dL) Protein (g/dL) pH

FIGURE 2.10 BRAIN VENTRICLES

AND

CSF 140–145 3 115–120 20 50–75 0.05–0.07 7.3

Blood Plasma 135–147 3.5–5.0 95–105 22–28 70–110 6.0–7.8 7.35–7.45

CSF COMPOSITION•

CSF circulates through the four brain ventricles (two lateral ventricles and a third and fourth ventricle) and in the subarachnoid space surrounding the brain and spinal cord. The electrolyte composition of the CSF is regulated by the choroid plexus, which

secretes the CSF. Importantly, the CSF has a lower [HCO3⫺] than plasma and therefore a lower pH. This allows small changes in blood PCO2 to cause changes in CSF pH, which in turn regulates the rate of respiration (see Chapter 5).

61

NEUROPHYSIOLOGY

Cerebrospinal Fluid (CSF): Circulation of CSF

Choroid plexus of lateral ventricle (phantom)

Superior sagittal sinus Subarachnoid space

Cistern of corpus callosum

Arachnoid granulations

Dura mater Arachnoid

Interventricular foramen (Monro)

Choroid plexus of 3rd ventricle Cerebral aqueduct (Sylvius) Lateral aperture (foramen of Luschka) Choroid plexus of 4th ventricle Dura mater

Median aperture (foramen of Magendie)

Arachnoid Subarachnoid space Central canal of spinal cord

Š

FIGURE 2.11 CIRCULATION

OF

CEREBROSPINAL FLUID•

CSF circulates through the four brain ventricles (two lateral ventricles and a third and fourth ventricle) and in the subarachnoid space surrounding the brain and spinal cord. Most of the CSF is

62

reabsorbed into the venous system through the arachnoid granulations and through the walls of the capillaries of the central nervous system and pia mater.

NEUROPHYSIOLOGY

Spinal Cord: Ventral Rami

Base of skull C1 vertebra (atlas) C1 spinal nerve Cervical plexus

C8 spinal nerve

Brachial plexus

T1 spinal nerve

Spinal dura mater 1st rib

Filaments of spinal nerve roots (T7 and T8)

Intercostal nerves T12 spinal nerve

L1 vertebra

12th rib

Conus medullaris

Lumbar plexus

L1 spinal nerve L5 vertebra

Cauda equina S1 spinal nerve

Sacral plexus

Sacrum (cut away) Termination of dural sac

Sciatic nerve

Coccygeal nerve

Coccyx

©

FIGURE 2.12 SPINAL CORD

AND

VENTRAL RAMI IN SITU•

The spinal cord gives rise to 31 pairs of spinal nerves that distribute segmentally to the body. These nerves are organized into plexuses that distribute to the neck (cervical plexus), upper limb (brachial plexus), and pelvis and lower limb (lumbosacral plexus). Motor

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

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NEUROPHYSIOLOGY

Spinal Cord: Membranes and Nerve Roots

Posterior view Ventral root of spinal nerve Dorsal root of spinal nerve Spinal sensory (dorsal root) ganglion

Ventral ramus of spinal nerve Dorsal ramus of spinal nerve Dura mater Arachnoid mater

Subarachnoid space Pia mater overlying spinal cord Filaments of dorsal root

Membranes removed: anterior view (greatly magnified) Gray matter White matter

Filaments of dorsal root Dorsal root of spinal nerve Filaments of ventral root Spinal sensory (dorsal root) ganglion Dorsal ramus of spinal nerve Ventral ramus of spinal nerve Ventral root of spinal nerve Spinal nerve Gray and white rami communicantes ©

FIGURE 2.13 SPINAL MEMBRANES

AND

NERVE ROOTS•

The spinal cord gives rise to 31 pairs of spinal nerves that distribute segmentally to the body. Motor fibers of these spinal nerves innervate skeletal muscle, and sensory fibers convey information back to the central nervous system from the skin, skeletal muscles, and joints.

64

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

NEUROPHYSIOLOGY

Peripheral Nervous System

Posterior horn

Dorsal root ganglion Sensory neuron cell body

Dorsal root

Anterior horn Motor neuron cell body Ventral root

Peripheral nerve Axon Myelin sheath

Motor neuron

Sensory neuron

Neuromuscular junction Skin Muscle

with

Š

FIGURE 2.14 PERIPHERAL NERVOUS SYSTEM• The peripheral nervous system (PNS) consists of all of the neural elements outside of the CNS (brain and spinal cord) and provides the connections between the CNS and all other body organ systems. The PNS consists of somatic and autonomic components. The somatic component innervates skeletal muscle and skin and is

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

The somatic component of the peripheral nerves contains both motor and sensory axons. Cell bodies of the motor neurons are found in the anterior horn gray matter, whereas the cell bodies of sensory neurons are located in the dorsal root ganglia.

65

NEUROPHYSIOLOGY

Autonomic Nervous System: Schema

Intracranial vessels

Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) Medulla oblongata Vagus nerve (X)

Pterygopalatine ganglion Lacrimal glands Otic ganglion

Parotid glands

mi Gray ra ntes nica u m m o c

C1 C2 C3 C4 C5 C6 C7 C8 Sweat gland

Ciliary ganglion Eye

Submandibular ganglion Sublingual and submandibular glands Peripheral cranial and facial vessels Larynx Trachea Bronchi Lungs

T1

Gray and white rami communican tes

Peripheral blood vessel

Pulmonary plexus

T2 T3 T4 T5 T6 T7 T8 T9 T10 T11

Heart Greater  Splanchnic Lesser  nerves Least 

Celiac ganglion Stomach

Lumbar splanchnic nerves

Pancreas Suprarenal glands Kidneys

m uni cantes

Intestines

L5

Inferior mesenteric ganglion Superior hypogastric plexus

Sigmoid colon Rectum Urinary bladder

a mi ay r

S2 S3 S4 S5 Coccygeal

Superior mesenteric ganglion

Descending colon

co m

S1

Gr

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

Aorticorenal ganglion

Liver Gallbladder Bile ducts

Arrector (smooth) T12 muscle of hair follicle Note: Above three L1 structures are shown at L2 only one level but occur at all levels L3 L4

Cardiac plexus

Pelvic splanchnic nerves

Inferior hypogastric plexus

Prostate External genitalia ©

Sympathetic fibers

Presynaptic Postsynaptic

Parasympathetic fibers

Presynaptic Postsynaptic

Antidromic conduction

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

66

a peripheral autonomic ganglion. Postganglionic axons of the autonomic nervous system innervate smooth muscle, cardiac muscle, and glands. Basically, the sympathetic division mobilizes our body (“fight or flight”) while the parasympathetic division regulates digestive and homeostatic functions. Normally, both divisions work in concert to regulate visceral activity (respiration, cardiovascular function, digestion, and associated glandular activity).

Autonomic Nervous System: Cholinergic and Adrenergic Synapses

Parotid gland

Glossopharyngeal nerve (IX) Medulla oblongata

NEUROPHYSIOLOGY

Internal carotid nerve Vagus nerve (X)

Larynx Trachea Bronchi Lungs

Heart Cervical sympathetic ganglia

Striated muscle

Sweat glands White ramus communicans

Gray ramus communicans

Thoracic part of spinal cord

Celiac ganglion

Peripheral arteries

Superior mesenteric ganglion

Upper lumbar part of spinal cord (L1-2 [3])

Hair follicles

Visceral arteries Gastrointestinal tract

Suprarenal gland

Inferior mesenteric ganglion Pelvic splanchnic nerves

Sacral part of spinal cord

Urinary bladder Urethra Prostate

C Cholinergic synapses A Adrenergic synapses

Sympathetic fibers

Presynaptic

Parasympathetic fibers

Postsynaptic

Presynaptic Postsynaptic

Somatic fibers Antidromic conduction

FIGURE 2.16 CHOLINERGIC

AND

Š

ADRENERGIC SYNAPSES: SCHEMA•

The autonomic nervous system (ANS) is a two-neuron chain, with the preganglionic neuron arising from the central nervous system and synapsing on a postganglionic neuron located in a peripheral autonomic ganglion. Acetylcholine is the neurotransmitter in both the sympathetic and parasympathetic ganglia. The parasympathetic division of the ANS releases acetylcholine at its postganglionic synapses and is characterized as having cholinergic (C) effects, whereas the sympathetic division releases predominantly noradren-

aline (norepinephrine) at its postganglionic synapses, causing adrenergic (A) effects (except on sweat glands, where acetylcholine is released). Although acetylcholine and noradrenaline are the chief transmitter substances, other neuroactive peptides often are colocalized with them and include such substances as gammaaminobutyric acid (GABA), substance P, enkephalins, histamine, glutamic acid, neuropeptide Y, and others.

67

NEUROPHYSIOLOGY

Hypothalamus Corpus callosum Septum pellucidum

Fornix

Lateral ventricle From hippocampal formation

Thalamus

Interthalamic Lateral adhesion hypothalamic area Paraventricular nucleus Medial Anterior hypothalamic area Anterior forebrain commissure Dorsal hypothalamic area bundle Dorsomedial nucleus Mamillothalamic tract Posterior area Lateral Periventricular preoptic Medial nucleus nucleus preoptic Nucleus intercalatus nucleus

Olfactory tract

Optic (II) nerve Optic chiasm

Fornix Red nucleus Ventromedial Mamillary nucleus complex Tuberohypophyseal tract Oculomotor (III) nerve Supraoptic nucleus Supraopticohypophyseal tract Posterior lobe of pituitary

Anterior lobe of pituitary

Cerebral peduncle

Dorsal longitudinal fasciculus Descending hypothalamic connections Pons Reticular formation Š

CHART 2.3 MAJOR FUNCTIONS OF THE HYPOTHALAMUS Hypothalamic Area Preoptic and anterior Posterior Lateral Ventromedial Supraoptic (subfornical organ and organum vasculosum) Paraventricular Periventricular

Major Functions* Heat loss center: cutaneous vasodilation and sweating Heat conservation center: cutaneous vasoconstriction and shivering Feeding center: eating behavior Satiety center: inhibits eating behavior ADH and oxytocin secretion (sensation of thirst) ADH and oxytocin secretion Releasing hormones for the anterior pituitary

*Stimulation of the center causes the responses listed.

FIGURE 2.17 SCHEMATIC RECONSTRUCTION

OF THE

HYPOTHALAMUS•

The hypothalamus, part of the diencephalon, controls a number of important homeostatic systems within the body, including temperature regulation, food intake, water intake, many of the endocrine systems (see Chapter 8), motivation, and emotional behavior. It receives inputs from the reticular formation (sleep/wake cycle

68

information), the thalamus (pain), the limbic system (emotion, fear, anger, smell), the medulla oblongata (blood pressure and heart rate), and the optic system, and it integrates these inputs for regulation of the functions listed.

NEUROPHYSIOLOGY

Limbic System

Genu of corpus callosum Head of caudate nucleus Columns of fornix Body of fornix Thalamus Uncus Crura of fornix Fimbria of hippocampus Hippocampus Commissure of fornix Splenium of corpus callosum Lateral ventricle

Body of fornix Columns of fornix

Commissure of fornix Crura of fornix

Mamillary bodies Amygdaloid bodies

FIGURE 2.18 HIPPOCAMPUS

AND

Hippocampus with fimbria

Š

FORNIX•

The limbic system includes the hypothalamus and a collection of interconnected structures in the telencephalon (cingulate, parahippocampal, and subcallosal gyri), as well as the amygdala and hip-

pocampal formation. The limbic system functions in linking emotion and motivation (amygdala), learning and memory (hippocampal formation), and sexual behavior (hypothalamus).

69

NEUROPHYSIOLOGY

The Cerebral Cortex

Motor

Premotor; orientation; eye and head movements

Sm I Sensory Sm II

Ms I Ms II

Sensory analysis

Prefrontal; inhibitory control of behavior; higher intelligence

Visual III Visual II Visual I

Language; reading; speech Auditory I

Motor control of speech

Auditory II Motor

Sm I Sensory Sm III ?

Ms I Ms II

Premotor Prefrontal; inhibitory control of behavior; higher intelligence

Visual III

Visual II Visual I

Cingulate gyrus (emotional behavior) and cingulum

©

Corpus callosum Hippocampal commissure

Olfactory

FIGURE 2.19 CEREBRAL CORTEX: LOCALIZATION

Anterior commissure

OF

FUNCTION

The cerebral cortex is organized into functional regions. In addition to specific areas devoted to sensory and motor functions, there are areas that integrate information from multiple sources. The cerebral cortex participates in advanced intellectual functions,

70

AND

ASSOCIATION PATHWAYS•

including aspects of memory storage and recall, language, higher cognitive functions, conscious perception, sensory integration, and planning/execution of complex motor activity. General cortical areas associated with these functions are illustrated.

NEUROPHYSIOLOGY

Hip Knee Ankle

Motor cortex

Internal capsule

Trunk Shoulder Elbow W Fin rist ge rs

Descending Motor Pathways

b um Th eck N Browd Eyeli Nares Lips Tongue Larynx

Toes

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

Midbrain

Basis pedunculi Pons

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

Basis pontis

Medulla Pyramids

Medulla Decussation of pyramids

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

Above midthoracic level

Spinal cord

Below midthoracic level

Motor endplate Anterior corticospinal tract Lateral corticospinal tract Motor endplate

Š

FIGURE 2.20 CORTICOSPINAL TRACTS• The corticospinal, or pyramidal, tract is the major motor tract that controls voluntary movement of the skeletal muscles, especially skilled movements of distal muscles of the limbs. All structures from the cerebral cortex to the anterior horn cells in the spinal

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

71

NEUROPHYSIOLOGY

Cerebellum: Afferent Pathways Superior cerebellar peduncle Middle cerebellar peduncle To contralateral cerebellar cortex

Cortical input

Leg

Nucleus reticularis tegmenti pontis

Arm

Fac e

Primary fissure

Pontine nuclei (contralateral) Spinal input Inferior olive Upper part of medulla oblongata Spinal input

Vestibular nerve and ganglion Lower part of medulla oblongata Cortical input Lateral reticular nucleus Spinal input Cervical part of spinal cord Motor interneuron Rostral spinocerebellar tract Spinal border cells Motor interneuron Lumbar part of spinal cord Clarke’s column Ventral spinocerebellar tract

Vestibular nuclei

To nodule and flocculus Inferior cerebellar peduncle

Reticulocerebellar tract Cuneocerebellar tract Gracile nucleus Main cuneate nucleus (relay for cutaneous information) External cuneate nucleus (relay for proprioceptive information) From skin (touch and pressure) From muscle (spindles and Golgi tendon organs) From skin and deep tissues (pain and Golgi tendon organs) From skin (touch and pressure) and from muscle (spindles and Golgi tendon organs) Dorsal spinocerebellar tract

Functional Subdivisions of Cerebellum Hemisphere Vermis InterLateral mediate part part Anterior lobe Leg zone Primary Arm zone fissure Face zone Middle (posterior) lobe

2nd spinal projection area (gracile lobule) ArchiLingula cerebellum Flocculus (vestibulocerebellum) Nodule Paleocerebellum Uvula (spinocerebellum) Pyramid Vermis Neocerebellum Middle vermis (pontocerebellum) Hemisphere

Posterolateral fissure Flocculonodular lobe

Schema of theoretical “unfolding” of cerebellar surface in derivation of above diagram

©

FIGURE 2.21 CEREBELLAR AFFERENT PATHWAYS• The cerebellum plays an important role in coordinating movement. It receives sensory information and then influences descending motor pathways to produce fine, smooth, and coordinated motion. The cerebellum is divided into three general areas: archicerebellum (also called vestibulocerebellum) paleocerebellum (also called spinocerebellum) and the neocerebellum (also called the cerebrocerebellum).

The archicerebellum is primarily involved in controlling posture and balance, as well as the movement of the head and eyes. It receives afferent signals from the vestibular apparatus and then sends efferent fibers to the appropriate descending motor pathways. The paleocere-

72

bellum primarily controls movement of the proximal portions of the limbs. It receives sensory information on limb position and muscle tone and then modifies and coordinates these movements through efferent pathways to the appropriate descending motor pathways. The neocerebellum is the largest portion of the cerebellum, and it coordinates the movement of the distal portions of the limbs. It receives input from the cerebral cortex and thus helps in the planning of motor activity (e.g., seeing a pencil and then planning and executing the movement of the arm and hand to pick it up).

NEUROPHYSIOLOGY

Cerebellum: Efferent Pathways

Excitatory endings Motor and premotor cerebral cortex

Inhibitory endings of Purkinje cells

Internal capsule

Ventral anterior and ventral lateral nuclei of thalamus

Cerebral peduncle

Mesencephalic reticular formation Red nucleus Fastigial nucleus Globose nuclei

Decussation of superior cerebellar peduncles Descending fibers from superior cerebellar peduncles Hook bundle of Russell

Emboliform nucleus Dentate nucleus

Section A–B viewed from below

Cerebellar cortex

Section B–C viewed from above

Vestibular nuclei Inferior cerebellar peduncle Inferior olive Lateral reticular nucleus Medulla oblongata Pontomedullary reticular formation

A Planes of section: red arrows indicate C direction of view

B

©

FIGURE 2.22 CEREBELLAR EFFERENT PATHWAYS• The cerebellum plays an important role in coordinating movement.

It influences descending motor pathways to produce fine, smooth, and coordinated motion. The archicerebellum is primarily involved in controlling posture and balance and movement of the head and eyes. It sends efferent fibers to the appropriate descending motor pathways. The paleocerebellum primarily controls movement of

the proximal portions of the limbs. It modifies and coordinates these movements through efferent pathways to the appropriate descending motor pathways. The neocerebellum coordinates the movement of the distal portions of the limbs. It helps in the planning of motor activity (e.g., seeing a pencil and then planning and executing the movement of the arm and hand to pick it up).

73

NEUROPHYSIOLOGY

Cutaneous Sensory Receptors Free nerve endings Hair shaft

Meissner’s corpuscle Pore of sweat gland

Stratum granulosum

Stratum spinosum Stratum basale

Internal sheath Hair follicle

Epidermis

Melanocyte Arrector muscle of hair Sebaceous gland Cuticle

Stratum corneum Stratum lucidum

External sheath Glassy membrane Connective tissue layer

Dermis

Dermal papilla (of papillary layer)

Reticular layer

Hair cuticle Sweat gland

Subcutaneous tissue

Hair matrix Papilla of hair follicle

Pacinian corpuscle Artery

Subcutaneous artery and vein

Vein Sensory nerves Elastic fibers Detail of Merkel’s disc

Basal epithelial cells

Skin ligaments (retinacula cutis)

Desmosomes

Motor (autonomic) nerve

Cross section

Lobulated nucleus

Mitochondria

Granulated vesicles

Expanded axon terminal

Schwann cell

AND

Axon

©

Schwann cells Detail of free nerve ending

CUTANEOUS RECEPTORS•

Cutaneous receptors respond to touch (mechanoreceptors), pain (nociceptors), and temperature (thermoreceptors). Several different types of receptors are present in skin. Meissner’s corpuscles have small receptive fields and respond best to stimuli that are applied at low frequency (i.e., flutter). The pacinian corpuscles are located in the subcutaneous tissue and have large receptive fields. They

74

Cutaneous nerve

Merkel cell

Cytoplasmic protrusion

FIGURE 2.23 SKIN

Basement membrane Axon terminal Mitochondrion Schwann cell

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

Merkel’s discs have small receptive fields and respond to touch and pressure (i.e., indenting the skin). Ruffini’s corpuscles have large receptive fields, and they also respond to touch and pressure. Free nerve endings respond to pain and temperature.

NEUROPHYSIOLOGY

Cutaneous Receptors: Pacinian Corpuscle Pacinian Corpuscle as Pressure Transducer

Pressure

To amplifier

Generator potential

Action potential 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)

1st node Myelin sheath Lamellated capsule Central core Unmyelinated axon terminal

Pressure To amplifier Generator potential

B. In absence of capsule, axon responds to slow as well as to rapid changes in pressure. Generator potential dissipates slowly, and there is no “off” response Na+

Pressure ⴙ

ⴙ

ⴚ

ⴚ

Action potential

ⴚ ⴙ ⴚ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴙ

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 ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴙ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ ⴙ

ⴙ

ⴙ

ⴙ

ⴚ

ⴚ

ⴚ

ⴚ

ⴚ

If resultant depolarization at 1st node is great enough to reach threshold, an action potential appears which is propagated along nerve fiber

©

FIGURE 2.24 PACINIAN CORPUSCLE• Pacinian corpuscles are mechanoreceptors that transduce mechanical forces (displacement, pressure, vibration) into action potentials that are conveyed centrally by afferent nerve fibers. As the viscoelastic lamellae are displaced, the unmyelinated axon terminal membrane’s ionic permeability is increased until it is capable of

producing a “generator potential.” As demonstrated in the figure, pacinian corpuscles respond to the beginning and end of a mechanical force while the concentric lamellae dissipate slow changes in pressure. In the absence of the capsule, the generator potential decays slowly and yields only a single action potential.

75

NEUROPHYSIOLOGY

Proprioception and Reflex Pathways: I Spinal Effector Mechanisms Dorsal horn interneuron

From motor neuron From cutaneous receptor

Proprioceptive fibers Dorsal horn interneuron

From muscle spindle

Flexor reflex interneuron Dorsal horn interneuron

Dorsal root ganglion To motor neuron Ventral root

To motor neuron ␣ motor axon

Schematic representation of motor neurons

E xt e

r n so

s

Fl e x o

rs

o rs

so

Flex

In lumbar enlargement of spinal cord

rs

In cervical enlargement of spinal cord

Ext e

n

©

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

76

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

NEUROPHYSIOLOGY

Proprioception and Reflex Pathways: II

Alpha motor neurons to extrafusal striated muscle end plates Gamma motor neurons to intrafusal striated muscle end plates Ia (A␣) fibers from annulospiral endings (proprioception) II (A␤) fibers from flower spray endings (proprioception); from paciniform corpuscles (pressure) and pacinian corpuscles (pressure) III (A␦) fibers from free nerve endings and from some specialized endings (pain and some pressure) IV (unmyelinated) fibers from free nerve endings (pain) Ib (A␣) fibers from Golgi tendon organs (proprioception) A␣ fibers from Golgi-type endings A␤ fibers from paciniform corpuscles and Ruffini terminals

Alpha motor neuron to extrafusal muscle fiber end plates

A␦ and C fibers from free nerve endings

Gamma motor neuron to intrafusal muscle fiber and plates II (A␤) fiber from flower spray endings

Extrafusal muscle fiber

Ia (A␣) fiber from annulospiral endings

Intrafusal muscle fibers Sheath Lymph space Nuclear bag fiber Nuclear chain fiber Detail of muscle spindle

FIGURE 2.26 MUSCLE

AND JOINT

©

Efferent fibers Afferent fibers

RECEPTORS•

Muscle spindles and Golgi tendon organs send afferent signals to the brain to convey the position of limbs and help coordinate muscle movement. Muscle spindles convey information on muscle tension and contraction (dynamic forces) and muscle length (static forces). The nuclear bag fibers respond to both dynamic and static

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

Intrafusal fibers maintain appropriate tension on the nuclear bag and nuclear chain fibers. If the muscle tension is too great (e.g., overstretching of muscle or too heavy a load), activation of the Golgi tendon organ causes a reflex relaxation of the muscle.

77

NEUROPHYSIOLOGY

Proprioception and Reflex Pathways: III

Ib fibers Ia fibers ⫹⫹⫹⫹ Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons ⫹⫹⫹ Gamma motor neurons

Golgi tendon organ

A. Passive stretch. Both intrafusal and extrafusal muscle fibers stretched; spindles activated. Reflex via Ia fibers and alpha motor neurons causes secondary contraction (basis of stretch reflexes, such as knee jerk).

Stretch is too weak to activate Golgi tendon organs Ib fibers ⫹⫹ Alpha activation from brain Ia fibers Extrafusal muscle fiber Intrafusal muscle fiber Inhibitory interneuron Alpha motor neurons ⫹⫹ Gamma motor neurons

Golgi tendon organ

B. Active contraction. Central excitation of alpha motor neurons only causes contraction of extrafusal muscle fibers with consequent relaxation of intrafusal fibers; spindles not activated. Tension is low; does not adjust to increased resistance. Tendon organ activated, causing relaxation Alpha and gamma Ib fibers ⫹⫹⫹ activation from brain Ia fibers ⫹⫹⫹⫹ Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons ⫹⫹⫹⫹ Gamma motor neurons ⫹⫹⫹⫹

Golgi tendon organ

C. Active contraction with gamma coactivation. Intrafusal as well as extrafusal fibers contract; spindles activated, reinforcing contraction stimulus via Ia fibers in accord with resistance. Tendon organ activated, causing relaxation if load is too great

FIGURE 2.27 PROPRIOCEPTIVE REFLEX CONTROL

OF

©

MUSCLE TENSION•

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

78

NEUROPHYSIOLOGY

Proprioception and Reflex Pathways: IV

B. Stretch reflex (reciprocal inhibition)

A. Afferent inhibition From extensor spindle receptor (Ia, II fibers)

From extensor spindle receptor (Ia, II fibers)

From flexor spindle (Ia, II fibers)

Axosomatic or axodendritic inhibitory synapse

Axoaxonic presynaptic inhibitory synapse

Excitatory synapse To extensors

To extensors

To flexors

C. Recurrent inhibition

D. Tendon organ reflex From extensor tendon organ (Ib fibers)

Inhibitory synapse Renshaw cells

Excitatory synapse

Collaterals To extensors

To synergistic muscles

To flexors E. Flexor withdrawal reflex

Nociceptive fibers Ipsilateral flexion

Contralateral extension

Inhibitory synapse

Excitatory synapse

Excitatory synapse

Inhibitory synapse

To extensors To flexors

To extensors To flexors

©

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

79

NEUROPHYSIOLOGY

Sensory Pathways: I

Cerebral cortex: postcentral gyrus Posterior limb of internal capsule Ventral posterolateral (VPL) nucleus of thalamus

Mesencephalon (cerebral peduncles) Medial lemniscus Gracile nucleus Spinothalamic tract Cuneate nucleus Lower part of medulla oblongata

Fasciculus gracilis Fasciculus cuneatus

Reticular formation

Dorsal (posterior) spinal root ganglion Proprioception, position

Cervical part of spinal cord

Touch, pressure, vibration

Lateral spinothalamic tract: pain, temperature

Pain, temperature

Spinocervical tract

Lumbar part of spinal cord

©

OF THE

BODY•

Pain, temperature, and pressure sensations below the head ultimately are conveyed to the primary somatosensory cortex (postcentral gyrus) by the anterolateral system (spinothalamic and spinoreticular tracts). The fasciculus gracilis and cuneatus of the spinal lemniscal system convey proprioceptive, vibratory, and tactile sen-

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Small myelinated and unmyelinated fibers

Lateral cervical nucleus

Ventral (anterior) spinothalamic tract: touch, pressure

FIGURE 2.29 SOMESTHETIC SYSTEM

Large myelinated fibers

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

NEUROPHYSIOLOGY

Sensory Pathways: II

Cerebral cortex: postcentral gyrus Ventral posteromedial (VPM) nucleus of thalamus Internal capsule

Midbrain (cerebral peduncles)

Dorsal trigeminal lemniscus Trigeminal mesencephalic nucleus Trigeminal motor nucleus Principal sensory trigeminal nucleus Touch, pressure Pain, temperature Proprioception

Ventral trigeminal lemniscus Pontine reticular formation

Trigeminal (semilunar) ganglion Ophthalmic n.

Maxillary n.

Pons

Sensory root and Motor root of mandibular n.

Medullary reticular formation Spinal trigeminal tract Spinal trigeminal nucleus Cervical part of spinal cord

Facial (VII) n.

Vagus (X) n.

Dorsolateral fasciculus (of Lissauer) Substantia gelatinosa (Iamina II)

FIGURE 2.30 SOMESTHETIC SYSTEM

OF THE

©

HEAD•

Nerve cells bodies for touch, pressure, pain, and temperature in the head are in the trigeminal (semilunar) ganglion of the trigeminal (CN V) nerve (blue and red lines in figure). Neuronal cell bodies mediating proprioception reside in the mesencephalic nucleus

of CN V (purple fibers). Most relay neurons project to the contralateral VPM nucleus of the thalamus and thence to the postcentral gyrus of the cerebral cortex, where they are somatotopically represented.

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NEUROPHYSIOLOGY

Sensory Pathways: III

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

C2 C3 C4 C5 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1

C2 C3 C4 C5 C6 C7 C8

C6

C6

T1 C5 C8

C7 C6 C8

C7

C7

S2, 3 L2

C8 S3 S4 S5

L3

T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S1 S2

S1 S2

L5 L1

L4

L2 L3

L5

S1 S2

L4 S1

S1

L5

L5

L4

L4 Levels of principal dermatomes Clavicles C5 C5, 6, 7 Lateral parts of upper limbs Medial sides of upper limbs C8, T1 Thumb C6 C6, 7, 8 Hand Ring and little fingers C8 Level of nipples T4

T10 T12 L1, 2, 3, 4 L4, 5, S1 L4 S1, 2, L5 S1 S2, 3, 4

Level of umbilicus Inguinal or groin regions Anterior and inner surfaces of lower limbs Foot Medial side of great toe Posterior and outer surfaces of lower limbs Lateral margin of foot and little toe Perineum

©

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

82

dorsal root is called a dermatome. This figure shows the dermatome segments and lists key dermatome levels used by clinicians. Variability and overlap occur, so all dermatome segments are only approximations.

NEUROPHYSIOLOGY

Visual System: Receptors

B. Section through retina

A. Eyeball

Iris

Lens

Axons at surface of retina passing via optic nerve, chiasm, and tract to lateral geniculate body

Cornea

Suspensory ligament

Ciliary body Anterior chamber

Inner limiting membrane

Ganglion cell

Posterior chamber

Müller cell (supporting glial cell) Amacrine cell Bipolar cell Horizontal cell Rod Cone Pigment cells of choroid

Ora containing serrata aqueous humor Vitreous humor Retina Choroid Sclera Fovea Optic nerve

Synaptic ending fully polarized

Synaptic ending depolarized C. Rod in dark

D. Rod in light

Photons of light Rhodopsin Metabolic energy Current flow Na+ permeability increased

Retinene + Opsin Vitamin A

Synaptic bar

Nucleus

Lumirhodopsin Metarhodopsin Retinene + Opsin Vitamin A

Centriole (basal body) Na+ permeability decreased

Circulation ©

FIGURE 2.32 VISUAL RECEPTORS• The rods and cones of the retina transduce light into electrical signals. As illustrated for the rod, light is absorbed by rhodopsin, and through the second messenger cGMP (not shown), Na⫹ channels in the membrane close and the cell hyperpolarizes. Thus, in the

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

This electrical response to light is distinct from other receptor responses, in which the response to a stimulus results in a depolarization of the receptor cell membrane.

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NEUROPHYSIOLOGY

Visual System: Visual Pathway

Central darker circle represents macular zone

G G Overlapping visual fields

A

Lightest shades represent monocular fields

A

B

B

H

H

Each quadrant a different color R RC

P Choroid

C

Projection on left retina

Projection on right retina Optic (II) nerves Optic chiasm

P Choroid

Periphery Macula Structure of retina (schematic): Projection on left A Amacrine cells dorsal lateral B Bipolar cells geniculate nucleus C Cones G Ganglion cells H Horizontal cells P Pigment cells R Rods

Optic tracts

Projection on right dorsal lateral geniculate nucleus

Lateral geniculate bodies

Calcarine fissure

Projection on left occipital lobe

Projection on right occipital lobe

©

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

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

NEUROPHYSIOLOGY

Auditory System: Cochlea

Cochlear nerve A. Membranous labyrinth within bony labyrinth (path of sound waves)

Semicircular canals

Utricle Saccule

Scala vestibuli Cochlear duct (scala media) Scala tympani B. Section through turn of cochlea

Round window

Scala vestibuli (perilymph); weakly +80 mV positive

Efferent nerve fibers

Oval window and stapes Vestibular (Reissner’s) membrane Cochlear duct (scala media; endolymph) Tectorial membrane Spiral ligament Bone Outer hair cells; ⫺60 mV

Scala tympani (perilymph); 0 mV

Afferent nerve fibers

Basilar membrane

Spiral ganglion C. Spiral organ of Corti

Inner hair cell; ⫺60 mV Hair cells Inner Outer

Tectorial membrane

Stereocilia

Rods and tunnel of Corti

Basilar membrane Supporting cells Afferent nerve fibers Spiral lamina Spiral ganglion Efferent nerve fibers As basilar membrane moves up, hairs are deflected outward, causing depolarization of hair cells and increased firing of afferent nerve fibers ©

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

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

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NEUROPHYSIOLOGY

Auditory System: Pathways

Acoustic area of temporal lobe cortex Medial geniculate body

Brachium of inferior colliculus Inferior colliculus Midbrain

Lateral lemnisci Nuclei of lateral lemnisci

Medulla oblongata

Correspondence between cochlea and acoustic area of cortex: Low tones Middle tones High tones

Dorsal cochlear nucleus Inferior cerebellar peduncle Ventral cochlear nucleus Cochlear division of vestibulocochlear nerve

Dorsal acoustic stria Reticular formation Trapezoid body Intermediate acoustic stria Superior olivary complex

Inner

Outer

Spiral ganglion Hair cells

Š

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

86

geniculate bodies) and then the acoustic cortex in the transverse gyrus of the temporal lobe, where information is tonotopically represented (low, middle, and high tones).

NEUROPHYSIOLOGY

Vestibular System: Receptors

A. Membranous labyrinth

Vestibular ganglion

Superior semicircular canal

Vestibular and cochlear divisions of vestibulocochlear n.

Maculae Saccule Utricle

Cristae within ampullae Horizontal semicircular canal Posterior semicircular canal

Cochlear duct (scala media)

B. Section of crista Opposite wall of ampulla Gelatinous cupula Hair tufts

C. Section of macula Otoconia Gelatinous otolithic membrane Hair tuft Hair cells Supporting cells Basement membrane Nerve fibers

Hair cells Nerve fibers Basement membrane

Excitation

D. Structure and innervation of hair cells

Inhibition

Kinocilium Kinocilium

Stereocilia Basal body Cuticle

Cuticle

Stereocilia Basal body

Hair cell (type I)

Hair cell (type II)

Supporting cells

Supporting cell

Afferent nerve calyx

Efferent nerve endings

Efferent nerve ending

Afferent nerve endings

Basement membrane

Myelin sheath

Myelin sheath Š

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

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

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NEUROPHYSIOLOGY

Vestibular System: Vestibulospinal Tracts

Excitatory endings Inhibitory endings

Superior Medial Lateral Inferior

Ascending fibers in medial longitudinal fasciculi

Vestibular nuclei Rostral Upper limb

Trunk

Ventral

Dorsal

To cerebellum

Lower limb Caudal Somatotopical pattern in lateral vestibular nucleus

Vestibular ganglion and nerve Motor neuron (controlling neck muscles) Medial vestibulospinal fibers in medial longitudinal fasciculi

Lateral vestibulospinal tract Excitatory interneuron

Excitatory endings to back muscles

?

Inhibitory interneuron

?

Lower part of cervical spinal cord

Fibers from maculae (gravitational stimuli)

To flexor muscles To extensor muscles

?

To axial muscles

Fibers from cristae (rotational stimuli)

Inhibitory ending

?

To axial muscles Inhibitory ending

Lumbar part of spinal cord

Excitatory ending Lateral vestibulospinal tract

Inhibitory interneuron

Excitatory synapse To flexor muscles To extensor muscles

©

FIGURE 2.37 VESTIBULOSPINAL TRACTS• Sensory input from the vestibular apparatus is used to maintain stability of the head and to maintain balance and posture. Axons convey vestibular information to the vestibular nuclei in the pons, and then secondary axons distribute this information to five sites: spinal

88

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

NEUROPHYSIOLOGY

Gustatory (Taste) System: Receptors

A. Tongue Foliate papillae

B. Section through vallate papilla Taste buds Duct of gustatory (Ebner’s) gland

C. Taste bud Epithelium Fungiform papillae

Vallate papillae

Basement membrane Nerve plexus

Microvilli Taste pore

Nerve fibers emerging from taste buds

Taste cells

Desmosomes Epithelium

Large nerve fiber Fibroblast Basement membrane Granules Schwann cell Small nerve fiber Collagen Intercellular space Large nerve fiber Microvilli D. Detail of taste pore E. Detail of base of receptor cells

Š

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

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

89

NEUROPHYSIOLOGY

Gustatory (Taste) System: Pathways

Ventral posteromedial (VPM) nucleus of thalamus Sensory cortex (just below face area) Lateral hypothalamic area Amygdala Mesencephalic nucleus and Motor nucleus of trigeminal n.

Pontine taste area Trigeminal (V) n.

Maxillary n.

Mandibular n.

Pons Pterygopalatine ganglion

Greater petrosal n.

Geniculate ganglion Facial (VII) n. and Nervus inermedius Rostral part of nucleus of solitary tract

Otic ganglion

Lingual n.

Chorda tympani

Glossopharyngeal (IX) n.

Fungiform papillae Foliate papillae

Lower part of medulla oblongata

Valiate papillae

Petrosal (inferior) ganglion of glossopharyngeal n.

Nodose (inferior) ganglion of vagus n.

Vagus (X) n.

Epiglottis Larynx

Superior laryngeal n. Š

FIGURE 2.39 TASTE PATHWAYS• Depicted here are the afferent pathways leading from the taste receptors to the brainstem and, ultimately, to the sensory cortex in the postcentral gyrus.

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NEUROPHYSIOLOGY

Olfactory System: Receptors

Olfactory bulb

Lateral nasal wall

A. Distribution of olfactory epithelium (blue area)

Cribriform plate of ethmoid bone

Septum B. Schema of section through olfactory mucosa Cribriform plate Schwann cell Olfactory gland Unmyelinated olfactory axons Basement membrane Sustentacular cells Endoplasmic reticulum Nucleus Olfactory cells Dendrites Terminal bars (desmosomes) Olfactory rod (vesicle) Villi Cilia Mucus ©

FIGURE 2.40 OLFACTORY RECEPTORS• The sensory cells that make up the olfactory epithelium respond to odorants by depolarizing. Like taste buds, an olfactory cell can respond to more than one odorant. There are six general odor

qualities that can be sensed: floral, ethereal (e.g., pears), musky, camphor (e.g., eucalyptus), putrid, and pungent (e.g., vinegar, peppermint).

91

NEUROPHYSIOLOGY

Olfactory System: Pathway

Efferent fibers Afferent fibers Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process

Fibers from contralateral olfactory bulb Fibers to contralateral olfactory bulb Anterior commissure

Tufted cell

Medial olfactory stria

Periglomerular cell

Olfactory trigone and olfactory tubercle

Glomerulus Olfactory nerve fibers

Anterior perforated substance Lateral olfactory stria Lateral olfactory tract nucleus Piriform lobe Uncus Amygdala (in phantom) Entorhinal area

Olfactory epithelium Olfactory nerves Olfactory bulb

Olfactory tract Anterior olfactory nucleus Cribriform plate of ethmoid bone

©

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

92

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

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