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 ©2002 Icon Custom Communications. All rights reserved.

The contents of this book may not be reproduced in any form without written authorization from Icon Custom Communications. Requests for permission should be addressed to Permissions Department, Icon Custom Communications, 295 North St., Teterboro NJ 07608, or can be made at www. Netterart.com.

NOTICE

Every effort has been taken to confirm the accuracy of the information presented. Neither the publisher nor the authors can be held responsible for errors or for 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, allow- ing 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 quali- ties is to miss the real strength and intent of the art. This intellectual process requires thorough under- standing of the topic, as Dr. Netter wrote: “Strange as it may seem, the hardest part of making a med- ical picture is not the drawing at all. It is the planning, the conception, the determination of point 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 anato- my. In pursuit of this principle Dr. Netter often integrates pertinent basic and clinical science ele- ments in his anatomic interpretations. Although he was chided for this heresy by a 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 shriv- eled 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 mono- graphs published over a period of more than 50 years, and in The Netter Collection of Medical Illustrations, this premier medical artist created superb illustrations of biological and physiological processes, disease pathology, clinical presentations, and medical procedures.

As a service to the medical community, Novartis Pharmaceuticals has commis- sioned this special edition of Netter’s work, which includes his beautiful and instructive illustrations of nervous system anatomy as well as his depictions of neurophysiological concepts and functions. We hope that readers will find Dr. Netter’s renderings of neurological form and function interesting and useful. Part 1 Neuroanatomy

Cerebrum—Medial Views...... 2 Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves: Schema...... 27 Cerebrum—Inferior View...... 3 Trigeminal Nerve (V): Schema ...... 28 Basal Nuclei (Ganglia)...... 4 Facial Nerve (VII): Schema ...... 29 Thalamus ...... 5 Vestibulocochlear Nerve (VIII): Schema. . . . . 30 Cerebellum ...... 6 Glossopharyngeal Nerve (IX): Schema ...... 31 Brainstem...... 7 Vagus Nerve (X): Schema ...... 32 Fourth Ventricle and Cerebellum ...... 8 Accessory Nerve (XI): Schema ...... 33 Accessory Nerve (XI) ...... 9 Hypoglossal Nerve (XII): Schema ...... 34 Arteries to Brain and Meninges ...... 10 Nerves of Heart ...... 35 Arteries to Brain: Schema ...... 11 Autonomic Nerves Arteries of Brain: Inferior Views ...... 12 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 Arteries of Brain: and Duodenum (continued) ...... 38 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 Nerves of Kidneys, Deep Veins of Brain...... 18 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 Median Nerve ...... 44 of Hypothalamus and Hypophysis...... 21 Ulnar Nerve ...... 45 Relation of Spinal Nerve Roots to Vertebrae . . . 22 Radial Nerve in Arm Autonomic Nervous System: and Nerves of Posterior Shoulder ...... 46 General Topography...... 23 Radial Nerve in Forearm ...... 47 Spinal Nerve Origin: Cross Sections...... 24 Sciatic Nerve and Posterior Olfactory Nerve (I): Schema ...... 25 Cutaneous Nerve of Thigh ...... 48

Optic Nerve (II) Tibial Nerve ...... 49 (Visual Pathway): Schema ...... 26 Common Fibular (Peroneal) Nerve...... 50 NEUROANATOMY Cerebrum: Medial Views

Sagittal section of Cingulate gyrus Paracentral sulcus brain in situ Cingulate sulcus Central sulcus (Rolando) Paracentral lobule Medial frontal gyrus Marginal sulcus Sulcus of corpus callosum Corpus callosum Fornix Precuneus Septum pellucidum Superior sagittal sinus Interventricular Choroid plexus foramen (Monro) of 3rd ventricle Interthalamic Stria medullaris adhesion of thalamus Thalamus and Parietooccipital 3rd ventricle sulcus Subcallosal Cuneus (parolfactory) Habenular area commissure Anterior Pineal body commissure Posterior Subcallosal commissure gyrus Calcarine sulcus Hypothalamic sulcus Straight sinus in tentorium Lamina cerebelli terminalis Great cerebral vein Supra- (Galen) optic recess Superior colliculus Optic chiasm Inferior colliculus Tectal (quadrigeminal) plate Tuber cinereum Cerebellum Hypophysis (pituitary gland) Superior medullary velum Mammillary body 4th ventricle and choroid plexus Cerebral peduncle Inferior medullary velum Pons Cerebral aqueduct Medulla oblongata (Sylvius)

Medial surface of cerebral Genu hemisphere: brainstem excised Rostrum of Trunk corpus callosum Splenium Cingulate gyrus Mammillothalamic Isthmus of cingulate gyrus fasciculus Parietooccipital sulcus Mammillary body Cuneus Uncus Calcarine sulcus Optic nerve (II) Lingual gyrus Olfactory tract Collateral sulcus Crus Body of fornix Rhinal sulcus Column Medial occipitotemporal gyrus Fimbria of hippocampus Occipitotemporal sulcus Dentate gyrus Lateral occipitotemporal gyrus Parahippocampal gyrus

2 Cerebrum: Inferior View NEUROANATOMY

Sectioned brainstem Frontal pole of cerebrum Longitudinal cerebral fissure

Straight gyrus Genu of corpus callosum

Olfactory sulcus Lamina terminalis

Orbital sulci Olfactory bulb

Orbital gyri Olfactory tract Optic chiasm Temporal pole Optic nerve (II) (cut) Lateral sulcus (Sylvius) Hypophysis Inferior temporal sulcus (pituitary gland)

Inferior temporal gyrus Anterior perforated substance

Optic tract

Tuber cinereum

Inferior (infero- Mammillary body lateral) margin of cerebrum Posterior perforated substance (in interpeduncular Rhinal sulcus fossa) Cerebral crus Uncus Lateral geniculate body Inferior temporal gyrus Substantia nigra

Medial geniculate Occipitotemporal body sulcus Red nucleus Lateral occipito- temporal gyrus Pulvinar of thalamus Superior colliculus (of Collateral sulcus corpora quadrigemina)

Cerebral aqueduct Parahippocampal gyrus Splenium of corpus callosum

Medial occipitotemporal gyrus Apex of cuneus

Calcarine sulcus Occipital pole of cerebrum Longitudinal cerebral fissure Isthmus of cingulate gyrus

3 NEUROANATOMY Basal Nuclei (Ganglia)

Horizontal sections through cerebrum A B

Genu of corpus callosum Head of caudate nucleus

Lateral ventricle Anterior limb of internal Genu Septum pellucidum capsule Posterior limb Column of fornix Putamen Lentiform nucleus Insula Globus pallidus (island of Reil) 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

Splenium of Hippocampus and fimbria corpus callosum Occipital (posterior) horn of lateral ventricle

Habenula Organization of basal nuclei (ganglia) A B Pineal body

Caudate Putamen Globus nucleus pallidus Cleft for internal capsule

Lentiform Striatum nucleus Caudate Body nucleus Head Thalamus Corpus striatum Levels of A A sections B B Basal nuclei above (ganglia) Pulvinar Lentiform nucleus Medial geniculate body (globus pallidus medial to putamen) Lateral geniculate body Amygdaloid body Tail of caudate nucleus Interrelationship of thalamus, lentiform nucleus, caudate nucleus and amygdaloid body (schema): left lateral view

4 Thalamus NEUROANATOMY

Interventricular foramen (Monro) Corpus callosum (cut) Tela choroidea (cut edge) Head of caudate nucleus of 3rd ventricle Septum pellucidum 3rd ventricle Columns of fornix Choroid plexus Anterior tubercle Superior thalamostriate vein Stria terminalis Pes hippocampi Temporal (inferior) horn Interthalamic adhesion 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 Posterior commissure Medial geniculate body Habenular commissure Brachium of superior colliculus Pineal body Brachium of inferior colliculus Collateral trigone Superior colliculus Calcar avis Inferior colliculus Occipital (posterior) horn Cerebellum of lateral ventricle Calcarine sulcus

Internal 3rd ventricle medullary Interthalamic lamina adhesion Pulvinar Anterior Median Lamina MD Intralaminar Medial lamina LP nuclei medullary LD VA Internal LP VL 3rd ventricle M VPL VP VI Reticular nucleus CM VPM VPM VPL

Thalamic nuclei Pulvinar External Lateral geniculate body medullary CM Centromedian Medial geniculate body lamina LD Lateral dorsal LP Lateral posterior Median nuclei M Medial Schematic representation of thalamus MD Medial dorsal (external medullary lamina and Schematic section VA Ventral anterior reticular nuclei removed) through thalamus VI Ventral intermedial (at level of broken VL Ventral lateral Lateral nuclei line shown in figure VP Ventral posterior Medial nuclei at right) VPL Ventral posterolateral VPM Ventral posteromedial 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 Declive (VI) Posterior lobe Postlunate fissure Folium (VII A) Superior semilunar (anseriform) lobule (H VII A) Horizontal fissure Inferior semilunar Posterior cerebellar notch (caudal) lobule (H VII B)

Anterior lobe Central lobule Inferior surface Superior vermis Wing of central lobule Lingula (I) Superior Superior medullary velum Middle Cerebellar peduncles Inferior Flocculus (H X) Flocculonodular lobe 4th ventricle Posterolateral (dorsolateral) Inferior medullary velum fissure Nodule (X) Retrotonsillar fissure Posterior lobe Inferior Uvula (IX) vermis Tonsil Pyramid (VIII) Biventer lobule (H VIII) Tuber (VII B) Secondary (postpyramidal) fissure Posterior cerebellar notch Horizontal fissure Inferior semilunar (caudal) lobule (H VII B)

Cerebral crus Decussation of superior cerebellar peduncles Medial longitudinal fasciculus 4th ventricle Nuclear layer of Superior medullary velum medulla oblongata

Fastigial Superior cerebellar peduncle Globose Cerebellar nuclei Lingula (I) Dentate Vermis Emboliform

Section in plane of superior cerebellar peduncle

6 Brainstem NEUROANATOMY

Posterolateral view Thalamus (cut surface) Lateral geniculate body

Pulvinars of thalami Optic tract 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) Glossopharyngeal (IX) and Facial nerve (VII) 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)

Lateral geniculate body Abducent nerve (VI) Facial nerve (VII) and Posterior perforated substance intermediate nerve Vestibulocochlear nerve (VIII) Pons Flocculus of cerebellum Middle cerebellar peduncle Choroid plexus of 4th ventricle Olive Glossopharyngeal nerve (IX) Pyramid Vagus nerve (X)

Ventral roots of 1st spinal nerve (C1) Hypoglossal nerve (XII) Accessory nerve (XI) Decussation of pyramids

7 NEUROANATOMY Fourth Ventricle and Cerebellum

Posterior view Habenular trigone Medial Geniculate bodies 3rd ventricle Lateral Pulvinar of thalamus Dorsal median sulcus Pineal body Superior cerebellar peduncle Superior colliculus Locus ceruleus Inferior colliculus Medial eminence Trochlear nerve (IV) Facial colliculus Vestibular area Superior medullary velum Dentate nucleus Superior of cerebellum Cerebellar peduncles Middle Inferior 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 Cuneate fasciculus Vagal trigone Gracile fasciculus Obex

Interthalamic adhesion Median sagittal section Posterior commissure Body of fornix Habenular commissure Thalamus (in 3rd ventricle) Pineal body Interventricular Splenium of corpus callosum foramen (Monro) Great cerebral vein (Galen) Anterior commissure Lamina terminalis Lingula (I) Hypothalamic sulcus Central lobule (II-III) Vermis of Cerebral peduncle Culmen (IV-V) cerebellum Cerebral aqueduct (Sylvius) Declive (VI) Superior colliculus Folium (VII A) Tectal (quadrigeminal) plate Superior medullary velum Inferior colliculus Pons Inferior medullary velum Medial longitudinal fasciculus Tuber (VII B) 4th ventricle Pyramid (VIII) Vermis of Choroid plexus of 4th ventricle Uvula (IX) cerebellum Medulla oblongata Nodulus (X) Median aperture (foramen of Magendie) Decussation of pyramids Choroid plexus of 4th ventricle Central canal of spinal cord Tonsil of cerebellum

8 Accessory Nerve (XI): Schema NEUROANATOMY

Nucleus ambiguus Cranial root of accessory nerve (joins vagus nerve and via recurrent laryngeal nerve supplies muscles of Vagus nerve (X) larynx, except cricothyroid)* Spinal root of accessory nerve Jugular foramen Foramen magnum 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 Arteries to Brain and Meninges

Left middle meningeal artery Middle cerebral artery

Posterior cerebral artery Anterior cerebral artery

Superior cerebellar artery Anterior communicating artery

Basilar artery Ophthalmic artery Left labyrinthine (internal acoustic) artery Posterior communicating Mastoid branch of artery left occipital artery Cavernous sinus Anterior inferior cerebellar artery Middle meningeal Posterior meningeal artery branch of left ascending pharyngeal artery

Posterior inferior cerebellar artery

Left and right Maxillary vertebral arteries artery (intracranial part) Superficial Posterior meningeal temporal branch of vertebral artery artery External Anterior meningeal carotid branch of vertebral artery artery

Posterior auricular artery Facial artery

Occipital artery Lingual artery

Internal carotid artery Ascending pharyngeal artery

Carotid sinus Superior laryngeal artery Carotid body Superior thyroid artery Vertebral artery (cervical part) Common carotid artery

Transverse process of C6 Ascending cervical artery (cut)

Deep cervical artery Inferior thyroid artery

Supreme intercostal artery Thyrocervical trunk

Costocervical trunk Brachiocephalic trunk

Subclavian artery Internal thoracic artery

10 Arteries to Brain: Schema NEUROANATOMY

Anterior cerebral artery Anterior communicating artery 1 Middle cerebral artery Ophthalmic artery Supraorbital artery Posterior communicating artery Supratrochlear artery Caroticotympanic branch 2 3 3 of internal carotid artery 3 Lacrimal artery 1 Dorsal nasal artery Posterior cerebral artery Middle meningeal artery Superior cerebellar artery 3 Angular artery Anterior tympanic artery 1 Superficial temporal artery 1 Middle meningeal artery Posterior auricular artery 4 Maxillary artery Facial artery

5 5 Occipital artery Basilar artery 4 Lingual artery Anterior inferior cerebellar artery 5 5 Ascending pharyngeal artery

Posterior inferior 5 Anterior spinal artery cerebellar artery Spinal segmental medullary branches External carotid artery 5 Vertebral artery Internal carotid artery 5 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

Anastomoses Arch 1 Right–Left Aorta Descending 2 Carotid–Vertebral Ascending 3 Internal carotid–External carotid 4 Subclavian–Carotid 5 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

Cerebral arterial circle (Willis) Distal medial striate artery (broken line) (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) NEUROANATOMY

Distal medial striate artery Vessels dissected out: inferior view (recurrent artery of Heubner)

Anterior cerebral artery Anteromedial central (perforating) (A2 segment) arteries Anterior communicating artery Hypothalamic artery Anterior cerebral artery (A segment) 1 Anterolateral central Ophthalmic artery (lenticulostriate) arteries Internal carotid artery

Middle cerebral artery Superior hypophyseal artery

Posterior communicating artery Inferior hypophyseal artery

Anterior choroidal artery Posterior cerebral artery (P2 segment) Thalamotuberal (P1 segment) (premammillary) artery

Posteromedial central Superior cerebellar artery (perforating) arteries

Basilar artery Thalamoperforating artery

Pontine arteries Posteromedial central (paramedian) arteries

Anterior inferior cerebellar artery Labyrinthine (internal acoustic) artery

Vertebral artery

Vessels in situ: inferior view

Anterior cerebral artery Anterior communicating artery Optic chiasm Hypothalamic artery Cavernous sinus Internal carotid artery Infundibulum (pituitary stalk) Superior hypophyseal artery and long hypophyseal portal veins Adenohypophysis (anterior Middle cerebral artery lobe of pituitary gland)

Inferior hypophyseal artery Neurohypophysis (posterior lobe of pituitary gland)

Posterior communicating artery Posteromedial central (perforating) arteries Efferent hypophyseal veins Superior cerebellar artery Posterior cerebral artery Basilar artery

13 NEUROANATOMY Arteries of Brain: Frontal View and Section

Corpus callosum Paracentral artery Medial frontal branches Anterolateral central (lenticulostriate) arteries Pericallosal artery Lateral frontobasal Callosomarginal artery (orbitofrontal) artery Polar frontal artery Prefrontal artery Anterior cerebral Precentral (pre-rolandic) arteries and central (rolandic) sulcal arteries Medial frontobasal (orbitofrontal) artery Anterior parietal (postcentral sulcal) Distal medial striate artery artery (recurrent artery of Heubner) Posterior parietal Internal carotid artery artery Branch to Anterior choroidal angular gyrus artery Temporal branches Posterior cerebral (anterior, middle artery and posterior) Superior cerebellar artery Middle cerebral artery and branches Basilar and pontine arteries (deep in lateral cerebral [sylvian] sulcus) Labyrinthine (internal acoustic) artery Anterior communicating artery Vertebral artery Posterior communicating artery Posterior inferior cerebellar artery Anterior inferior cerebellar artery Anterior spinal artery Posterior spinal artery Falx cerebri

Callosomarginal arteries Corpus striatum and (caudate and lentiform nuclei) Pericallosal arteries (branches of anterior Anterolateral central cerebral arteries) (lenticulostriate) arteries Insula (island of Reil) Trunk of corpus callosum

Limen of insula Internal capsule Precentral (pre-rolandic), central (rolandic) sulcal Septum pellucidum and parietal arteries Rostrum of corpus callosum Lateral cerebral (sylvian) sulcus Anterior cerebral arteries Temporal branches of middle cerebral artery Distal medial striate artery (recurrent artery of Heubner) Temporal lobe Anterior communicating artery Middle cerebral artery Optic chiasm Internal carotid artery

14 Arteries of Brain: Lateral and Medial Views NEUROANATOMY

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 Prefrontal sulcal cerebral artery artery

Terminal branches of anterior cerebral artery

Lateral frontobasal (orbitofrontal) artery

Left middle cerebral artery

Left anterior cerebral artery Occipitotemporal Anterior communicating artery branches

Right anterior cerebral artery Posterior temporal branch Middle temporal branch Left internal carotid artery Superior and inferior terminal branches (trunks) Polar temporal artery Anterior temporal branch

Paracentral artery Pericallosal artery Medial Posterior Cingular branches frontal Intermediate branches Anterior Right posterior cerebral artery Precuneal artery Callosomarginal Dorsal branch artery to corpus callosum Parietooccipital branch Polar frontal artery Calcarine branch Right anterior cerebral artery

Medial fronto- basal (orbito- frontal) artery

Anterior communicating artery (cut) Medial occipital artery Distal medial striate artery Posterior temporal branch (recurrent artery of Heubner) 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 Anterior choroidal artery Choroid plexuses of lateral ventricles Crura of fornix Pulvinars of left and right thalami Splenium of corpus callosum Anterolateral central (lenticulostriate) arteries Occipital (posterior) horn of right lateral ventricle Heads of caudate nuclei Right dorsal branch to corpus callosum (posterior pericallosal artery) Septum pellucidum Parietooccipital Branches of Corpus callosum right posterior Calcarine cerebral artery Anterior cerebral arteries Longitudinal cerebral fissure

Superior colliculi

Superior vermian Optic nerve (II) branch IV Ophthalmic artery III Posterior medial V Anterior choroidal artery cerebral artery to choroid plexus of 3rd ventricle Middle VIII cerebral artery Posterior lateral choroidal artery Posterior VII communicating artery VI Lateral (marginal) branch IX Thalamoperforating arteries X Inferior vermian artery Left internal carotid artery (phantom) XI Basilar artery Choroidal branch to 4th ventricle (phantom) and Pontine arteries Cerebellar tonsillar branch Labyrinthine (internal acoustic) artery of posterior inferior cerebellar artery Posterior cerebral artery Outline of 4th ventricle (broken line)

Superior cerebellar artery Posterior meningeal branch of vertebral artery Anterior inferior cerebellar artery Posterior inferior cerebellar artery (PICA) Anterior meningeal branch of vertebral artery Left posterior spinal artery Temporal branches of posterior cerebral artery Left vertebral artery Anterior spinal artery

16 Veins of Posterior Cranial Fossa NEUROANATOMY

Left superior and inferior colliculi Left pulvinar Basal vein (Rosenthal) Right pulvinar Posterior mesencephalic vein Internal cerebral veins Medial geniculate body Splenium of corpus callosum Lateral Great cerebral vein (Galen) mesencephalic vein Dorsal vein of corpus callosum Lateral geniculate body Inferior sagittal sinus Left thalamus Straight sinus (cut surface) Falx cerebri Optic tract Confluence of sinuses Tentorium Inferior thalamo- cerebelli (cut) Left transverse striate veins sinus (cut) Deep middle cerebral Superior vein (cut) sagittal sinus Anterior cerebral vein Optic nerve (II)

C C

CL D F L TU Superior vermian N P vein U Inferior vermian vein Anterior ponto- Falx cerebelli (cut) mesencephalic vein T and occipital sinus Inferior cerebellar Trigeminal nerve (V) hemispheric veins Transverse pontine vein Intraculminate vein Petrosal vein (draining Superior cerebellar vein (inconstant) to superior petrosal sinus) Preculminate vein Lateral pontine vein Precentral cerebellar vein Anteromedian medullary vein Superior retrotonsillar vein Parts of cerebellum Vein of lateral recess of 4th ventricle (Inferior retrotonsillar) vein of cerebellomedullary L Lingula TU Tuber cistern Superior, middle and CL Central lobule P Pyramid inferior cerebellar peduncles Posterior spinal vein C Culmen U Uvula D Declive N Nodule Anterior spinal vein 4th ventricle F Folium 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 Inferior cerebral Medial geniculate body veins Pulvinar of thalamus Splenium of corpus callosum

Great cerebral vein (Galen) Inferior anastomotic vein (Labbé)

Dissection: inferior view

18 Subependymal Veins of Brain NEUROANATOMY

Posterior veins of septum pellucidum Lateral direct vein Superior thalamic veins Posterior terminal vein of caudate nucleus (posterior part of thalamostriate vein) Superior choroid 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 Inferior sagittal callosum 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 Veins on lateral wall of ventricle 4th ventricle Veins on medial wall and floor of ventricle Lateral and median apertures of 4th ventricle All other veins

19 NEUROANATOMY Hypothalamus and Hypophysis

Septum pellucidum

Thalamus

Fornix

Hypothalamic sulcus

Anterior commissure

Paraventricular Posterior Principal Dorsomedial nuclei of Supraoptic hypothalamus Ventromedial Arcuate (infundibular) Mammillary Mammillothalamic tract Optic chiasm Dorsal longitudinal Infundibulum (pituitary stalk) fasciculus and other descending pathways Hypophysis (pituitary gland)

Lamina terminalis Hypothalamic sulcus Paraventricular hypothalamic nucleus

Supraoptic hypothalamic nucleus

Supraopticohypophyseal tract

Tuberohypophyseal tract Mammillary Hypothalamohypophyseal tract body

Infundibulum (pituitary stalk) Arcuate (infundibular) nucleus

Pars tuberalis Median eminence of tuber cinereum Adenohypophysis Fibrous trabecula (anterior lobe of Neurohypophysis pituitary gland) Pars intermedia Infundibular stem (posterior lobe of pituitary gland) Pars distalis Infundibular process Cleft

20 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 Efferent hypophyseal vein to cavernous sinus to cavernous sinus

Secondary plexus Neurohypophysis of hypophyseal (posterior lobe of portal system pituitary gland)

Capillary plexus of infundibular process Adenohypophysis (anterior lobe of pituitary gland)

Efferent hypophyseal vein to cavernous sinus

Inferior hypophyseal artery Efferent hypophyseal veins to cavernous sinus

21 NEUROANATOMY Relation of Spinal Nerve Roots to Vertebrae

L4 C1 C1 spinal nerve exits Base C1 above C1 vertebra C2 of skull C2 L4 C3 C3 Cervical C4 enlargement C4 L5 C5 C5 C6 C8 spinal nerve L5 C6 C7 exits below C7 C7 vertebra C8 (there are 8 cervical T1 nerves but only T1 T2 7 cervical vertebrae) T2 T3 S1 T3 T4 T4 T5 S2 T5 T6 T6 T7 Lumbar disc protrusion does not usually affect T7 nerve exiting above disc. Lateral protrusion T8 T8 at disc level L4–5 affects L5 spinal nerve, not T9 L4 spinal nerve. Protrusion at disc level L5–S1 T9 affects S1 spinal nerve, not L5 spinal nerve T10 T10 T11 Lumbar T11 enlargement T12 L4 T12 L1 Conus medullaris (termination of L1 spinal cord) L4 L2 L2 L5 L3 L5 L3 Cauda equina Internal terminal L4 filum (pial part) L4

L5 S1 L5 Sacrum S2

S1 S3 External S2 terminal filum (dural part) S3 Termination of S4 S4 dural sac S5 S5 Coccygeal nerve

Coccyx Coccygeal nerve

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

22 Autonomic Nervous System: General Topography NEUROANATOMY

Oculomotor nerve (III) Ciliary ganglion

Facial nerve (VII) Pterygopalatine ganglion

Glossopharyngeal nerve (IX) Otic ganglion

Vagus nerve (X) Chorda tympani nerve

Internal carotid nerve and plexus Lingual nerve

Superior cervical sympathetic ganglion Submandibular ganglion C4 spinal nerve Pharyngeal and superior laryngeal branches of vagus nerve Middle cervical sympathetic ganglion

Vertebral ganglion Recurrent laryngeal branch of vagus nerve

Cervicothoracic (stellate) ganglion Superior cervical Cardiac branches Inferior cervical of vagus nerve Sympathetic trunk Thoracic Cardiac plexus Cervical (sympathetic) Superior Middle cardiac nerves Anterior Pulmonary plexuses Inferior Posterior

Thoracic (sympathetic) cardiac nerves Esophageal plexus

6th intercostal nerve Thoracic aortic plexus (ventral ramus of T6 spinal nerve) Anterior vagal trunk Sympathetic trunk Posterior vagal trunk 6th thoracic sympathetic ganglion Celiac ganglion Gray and white rami communicantes Celiac trunk and plexus Greater splanchnic nerve Superior mesenteric ganglion Lesser splanchnic nerve Superior mesenteric artery Least splanchnic nerve and plexus

Aorticorenal ganglion Intermesenteric (abdominal aortic) plexus Lumbar splanchnic nerves (sympathetic) Inferior mesenteric ganglion Gray rami communicantes Inferior mesenteric artery Sacral splanchnic nerves (sympathetic) and plexus

Pelvic splanchnic nerves Superior hypogastric plexus (sacral parasympathetic outflow) Parasympathetic branch from inferior hypogastric plexus to Sciatic nerve descending colon

Inferior hypogastric Hypogastric nerves (pelvic) plexus 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 Spinal nerve meningeal Ventral ramus branches of (intercostal nerve) spinal nerve Dorsal ramus Pleura

Lung

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

Section through lumbar vertebra of dorsal Lateral branch ramus Sympathetic of spinal Medial branch ganglion Dura mater nerve

Gray ramus Arachnoid mater Internal vertebral communicans (epidural) venous plexus Ventral root Fat in epidural Spinal nerve space Ventral ramus (contributes to lumbar plexus)

Dorsal ramus

Dorsal and ventral Spinal sensory (dorsal root) ganglion roots of lumbar and Dorsal root sacral spinal nerves forming cauda equina Conus medullaris *Leptomeninges

24 Olfactory Nerve (I): Schema NEUROANATOMY

Subcallosal (parolfactory) area

Septal area and nuclei Olfactory bulb cells: schema Fibers from Contralateral Efferent fibers to Fibers to olfactory bulb olfactory bulb Afferent fibers from bulb Anterior commissure to central connections and contralateral bulb 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 tract

Olfactory mucosa Olfactory trigone and olfactory tubercle Olfactory nerves (I) Lateral olfactory stria Uncus Olfactory bulb Lateral olfactory tract nucleus Hippocampal Cribriform plate of ethmoid bone fimbria Anterior perforated substance Anterior olfactory nucleus Amygdaloid body (phantom) Dentate gyrus

Piriform lobe Parahippocampal gyrus

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

G Central darker G circle represents macular zone Overlapping Lighter shades A visual fields A represent monocular fields B B Each quadrant H H a different color

Projection on Projection on RRC C right retina left retina

P P Choroid Choroid Optic nerves (II) Optic chiasm Periphery Macula

Structure of retina: schema Projection on left Projection on right A Amacrine cells dorsal lateral dorsal lateral B Bipolar cells geniculate nucleus geniculate nucleus C Cones Optic tracts G Ganglion cells H Horizontal cells P Pigment cells Lateral R Rods geniculate bodies

Optic radiation Optic radiation

Calcarine sulcus

Calcarine sulcus

Projection on left Projection on right occipital lobe occipital lobe

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

Long ciliary nerve Ciliary ganglion

Short ciliary nerves Posterior ethmoidal nerve Abducent nucleus

Anterior ethmoidal nerve Sensory root of ciliary ganglion Trochlear nucleus Superior oblique muscle Sympathetic root of ciliary ganglion Levator palpebrae Oculomotor nucleus superioris muscle Superior division of oculomotor nerve Superior Accessory oculomotor rectus muscle Frontal nerve (cut) (Edinger-Westphal) nucleus (parasympathetic) Lacrimal nerve (cut)

Nasociliary nerve Trochlear nerve (IV)

Oculomotor nerve (III)

Ophthalmic nerve (V1)

Infraorbital nerve Abducent nerve (VI) Zygomatic nerve (cut) Pterygopalatine ganglion Mandibular nerve (V3) Inferior oblique muscle Internal carotid artery Inferior division of Ciliary muscle and nerve plexus oculomotor nerve Dilator muscle of pupil Maxillary nerve (V ) Medial rectus muscle 2 Sphincter muscle of pupil Lateral rectus muscle and Inferior rectus muscle abducent nerve (turned back) Efferent fibers Afferent fibers Parasympathetic root Cavernous plexus of ciliary ganglion Sympathetic fibers Common tendinous ring Parasympathetic fibers

27 NEUROANATOMY Trigeminal Nerve (V): Schema

Trigeminal nerve (V) ganglion and nuclei Ophthalmic nerve (V1) Motor nucleus Efferent fibers Mesencephalic nucleus Afferent fibers Tentorial (meningeal) branch Principal sensory nucleus Proprioceptive fibers Nasociliary nerve Spinal tract and nucleus Parasympathetic fibers Lacrimal nerve Sympathetic fibers 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

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 Facial nerve (VII) and posterior superior medial) 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 Superficial (to temporalis muscle) temporal branches Lateral pterygoid Articular branch and masseteric nerves and anterior auricular nerves Tensor veli palatini and medial pterygoid nerves Auriculotemporal nerve Submandibular Buccal nerve Inferior Parotid branches ganglion alveolar nerve Mental nerve Meningeal branch Inferior dental plexus Mylohyoid nerve Otic ganglion Lesser petrosal nerve (from Lingual nerve Mandibular nerve (V3) Tensor tympani nerve glossopharyngeal nerve [IX])

28 Facial Nerve (VII): Schema NEUROANATOMY

Greater petrosal nerve Facial nerve (VII) Internal acoustic meatus Deep petrosal nerve (from internal carotid plexus) Geniculate ganglion Intermediate nerve Lesser petrosal nerve Internal carotid plexus Motor nucleus of facial nerve (on internal carotid artery) Nerve (vidian) of pterygoid canal Superior salivatory nucleus Otic ganglion Solitary tract nucleus Pterygopalatine ganglion

Facial muscles Frontal belly (frontalis) of occipitofrontalis Orbicularis oculi Corrugator supercilii Zygomaticus major Zygomaticus minor T emporal Procerus Levator labii superioris

branches Levator labii superioris alaeque nasi Levator anguli oris Nasalis

Zygomatic branches Depressor 2 Occipital anterior ⁄3 septi nasi aste: T tongue belly of Buccal (occipitalis) of Orbicularis branches oris occipitofrontalis muscle Depressor Occipital anguli oris branch of posterior Depressor labii branch auricular inferioris nerve Branches to auricular muscles Mentalis Cervical (Risorius) Posterior auricular nerve (not shown) Marginal Nerve to stapedius muscle mandibular Buccinator branch Stylomastoid foramen Platysma Tympanic plexus Tympanic nerve (Jacobson) Sublingual gland (from glossopharyngeal nerve) Submandibular gland Glossopharyngeal nerve (IX) Efferent fibers Submandibular ganglion Afferent fibers Digastric muscle (posterior belly) Parasympathetic fibers Lingual nerve (from trigeminal nerve) Stylohyoid muscle Sympathetic fibers Chorda tympani nerve 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 Medial acoustic Ampulla of superior meatus semicircular duct Vestibular Superior Anterior Utricle nuclei Cochlear (diagrammatic) Inferior Posterior nuclei Ampulla of posterior Lateral semicircular duct Inferior cerebellar peduncle (to cerebellum) Saccule

Superior division Vestibular ganglion of vestibular nerve Inferior division

30 Glossopharyngeal Nerve (IX): Schema NEUROANATOMY

Efferent fibers Spinal tract and spinal nucleus of trigeminal nerve Afferent fibers Solitary tract nucleus Parasympathetic fibers Tympanic nerve (Jacobson) Nucleus ambiguus Tympanic cavity and plexus Inferior salivatory nucleus Stylomastoid foramen Geniculate ganglion of facial nerve Caroticotympanic nerve (from internal carotid plexus) 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 Stylopharyngeus muscle (and branch Glossopharyngeal from glossopharyngeal nerve) nerve (IX) Jugular foramen

Communication to auricular branch of vagus nerve

Superior and Inferior ganglia of Glossopharyngeal nerve

Communication to facial nerve (VII) Taste and somatic Vagus nerve (X) sensation: posterior Superior cervical 1 ⁄3 of tongue 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 Vagus Nerve (X): Schema

Posterior nucleus of vagus nerve (parasympathetic SEE ALSO PLATE 160 Glossopharyngeal nerve (IX) and visceral afferent)

Meningeal branch of vagus nerve Solitary tract nucleus (visceral afferents including taste) Auricular branch of vagus nerve Spinal tract and spinal Pharyngotympanic (auditory) tube nucleus of trigeminal nerve (somatic afferent) Levator veli palatini muscle Nucleus ambiguus (motor to pharyngeal Salpingopharyngeus and laryngeal muscles) muscle Cranial root of accessory nerve* Palatoglossus muscle (see next plate) Palatopharyngeus Vagus nerve (X) muscle Jugular foramen Superior pharyngeal constrictor muscle Superior ganglion of vagus nerve

Stylopharyngeus muscle Inferior ganglion of vagus nerve

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 Communicating branch of vagus nerve to Cricothyroid muscle carotid branch of glossopharyngeal nerve

Trachea Pharyngeal plexus

Esophagus Superior laryngeal nerve: Internal branch (sensory and parasympathetic) Right subclavian artery External branch (motor to cricothyroid muscle)

Right recurrent laryngeal nerve Superior cervical cardiac branch of vagus nerve

Heart Inferior cervical cardiac branch of vagus nerve

Hepatic branch of anterior Thoracic cardiac branch of vagus nerve vagal trunk (in lesser omentum) Left recurrent laryngeal nerve (motor to muscles of larynx Celiac branches from anterior except cricothyroid; sensory and parasympathetic to and posterior vagal trunks larynx below vocal folds; parasympathetic, efferent and to celiac plexus afferent to upper esophagus and trachea)

Celiac and superior mesenteric Pulmonary plexus ganglia and celiac plexus Cardiac plexus Hepatic plexus Esophageal plexus Gallbladder and bile ducts Anterior vagal trunk

Liver Gastric branches of anterior vagal trunk (branches from posterior trunk behind stomach) Pyloric branch from hepatic plexus Vagal branches (parasympathetic motor, secretomotor and afferent fibers) accompany Pancreas superior mesenteric artery and its branches usually as far as left colic (splenic) flexure Duodenum Small intestine Ascending colon Efferent fibers Cecum Afferent fibers Appendix Parasympathetic fibers

32 Accessory Nerve (XI): Schema NEUROANATOMY

SEE ALSO PLATE 28

Nucleus ambiguus Cranial root of accessory nerve (joins vagus nerve and via recurrent laryngeal nerve supplies muscles of Vagus nerve (X) larynx, except cricothyroid)* Spinal root of accessory nerve Jugular foramen Foramen magnum 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) Meningeal branch (in hypoglossal canal)

Hypoglossal nucleus Superior longitudinal Intrinsic muscles Transverse of tongue and vertical Styloglossus Inferior muscle longitudinal

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 Genioglossus ansa cervicalis muscle

Internal carotid artery Geniohyoid muscle

Hyoglossus muscle Inferior root of ansa cervicalis

Thyrohyoid muscle Ansa cervicalis

Omohyoid muscle Internal jugular vein (superior belly)

Sternohyoid muscle Common carotid artery

Sternothyroid muscle

Omohyoid muscle (inferior belly) Efferent fibers Afferent fibers

34 Nerves of Heart NEUROANATOMY

Superior cervical Superior cervical sympathetic ganglion sympathetic ganglion

Vagus nerve (X) Vagus nerve (X)

(Conjoined sympathetic and Superior cervical vagal) superior cervical cardiac nerves (sympathetic) cardiac nerve

Middle cervical Superior cervical sympathetic ganglion (vagal) cardiac nerve

Middle cervical Middle cervical (sympathetic) cardiac nerve sympathetic ganglion

Phrenic nerve Phrenic nerve

Inferior cervical Middle cervical (vagal) cardiac nerve (sympathetic) cardiac nerve Inferior cervical Vertebral ganglion (vagal) cardiac nerve Inferior thyroid artery Vertebral ganglion Vertebral artery Cervicothoracic (stellate) ganglion Cervicothoracic (stellate) ganglion Inferior cervical sympathetic Ansa subclavia cardiac nerves Recurrent laryngeal nerve

Inferior cervical 3rd thoracic (sympathetic) cardiac nerves sympathetic ganglion

Thoracic cardiac branch Thoracic (sympathetic) of vagus nerve cardiac branches

4th thoracic Thoracic cardiac sympathetic ganglion branch of vagus nerve Thoracic (sympathetic) cardiac branches Recurrent laryngeal Cardiac plexus nerve

Phrenic nerve (cut)

35 NEUROANATOMY Autonomic Nerves and Ganglia of Abdomen

Right sympathetic trunk Anterior, Posterior Thoracic duct vagal trunks

Right greater Left gastric artery and lesser and plexus splanchnic nerves Celiac ganglia

Right phrenic nerve Left greater splanchnic nerve Inferior phrenic Left lesser arteries and plexuses splanchnic nerve Right greater Splenic artery and lesser and plexus splanchnic nerves Common hepatic artery and plexus Right suprarenal plexus Superior mesenteric ganglion and plexus Right aortico- Left aorticorenal renal ganglion ganglion Right least Left sympathetic splanchnic nerve trunk Right renal Intermesenteric artery and plexus (aortic) plexus

Right Inferior mesenteric sympathetic trunk ganglion

White and gray Left colic artery rami communicantes and plexus Inferior mesenteric Cisterna chyli artery and plexus Gray ramus communicans Left common iliac artery and plexus 3rd lumbar ganglion of sympathetic trunk Superior rectal artery and plexus 2nd and 3rd lumbar splanchnic nerves Superior hypogastric plexus Right ureter and plexus Internal and external iliac arteries and Right testicular (ovarian) plexuses artery and plexus Right and left 4th lumbar splanchnic nerve hypogastric nerves to inferior hypo- 1st sacral ganglion gastric (pelvic) plexus of sympathetic trunk Gray rami communicantes Left sacral plexus Pelvic splanchnic nerves

36 Nerves of Stomach and Duodenum NEUROANATOMY

Right and left inferior phrenic arteries and plexuses Hepatic branch of anterior vagal trunk

Anterior and posterior layers of lesser omentum Anterior vagal trunk

Branch from hepatic plexus to Celiac branch of posterior vagal trunk cardia via lesser omentum Celiac branch of anterior vagal trunk Right greater splanchnic nerve 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)

Plexus on gastro-omental Posterior gastric branch of posterior vagal trunk (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 Right inferior phrenic artery and plexus 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 Greater, Phrenic ganglion Lesser, Branch from right inferior phrenic Least plexus to cardia of stomach splanchnic nerves 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 pancreatico- Celiac branches duodenal arteries Right greater, of anterior and posterior Plexus on gastroduodenal artery lesser and least vagal trunks Plexus on posterior superior splanchnic nerves and posterior inferior Left gastric pancreaticoduodenal arteries Celiac ganglia artery and plexus Left greater, Superior mesenteric ganglion and plexus Right aortico- lesser and least renal ganglion splanchnic nerves Superior mesenteric ganglion and plexus Left aorticorenal ganglion

38 Nerves of Small Intestine NEUROANATOMY

Recurrent branch of left inferior phrenic artery and plexus to esophagus

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 Marginal artery and plexus

Posterior vagal trunk Esophagus

Celiac branches of anterior Left inferior phrenic and posterior vagal trunks artery and plexus

Right inferior phrenic artery and plexus Left gastric artery and plexus Right greater splanchnic nerve Left greater splanchnic Celiac ganglia and plexus nerve

Right lesser and Left suprarenal least splanchnic plexus nerves Left lesser and Right aortico- least splanchnic renal ganglion nerves

Superior Left aorticorenal mesenteric ganglion ganglion Left renal artery and plexus Middle colic artery 1st left lumbar and plexus splanchnic nerve Inferior Left lumbar pancreatico- sympathetic trunk duodenal arteries Intermesenteric and plexuses (aortic) plexus Right colic Left colic artery artery and plexus and plexus Inferior Ileocolic mesenteric artery ganglion, artery and plexus and plexus

Cecal and Sigmoid appendicular arteries arteries and plexuses and plexuses Superior Right internal hypogastric iliac artery plexus and plexus (cut) Superior Sacral sympathetic trunk rectal artery Right sacral plexus and plexus

Pelvic splanchnic nerves Right and left hypogastric Middle rectal artery and plexus nerves

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

40 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 Nerves of Pelvic Viscera: Male

Anterior vagal trunk T10 spinal nerve (anterior ramus)

Posterior vagal trunk White and gray rami communicantes and Celiac branch Greater Lesser Splanchnic nerves Inferior phrenic arteries and plexuses Least Left gastric artery and gastric plexus Diaphragm Celiac ganglia, plexus and trunk Left renal artery Left aorticorenal ganglion and plexus

Superior mesenteric ganglion L1 spinal nerve (anterior ramus) Superior mesenteric artery and plexus Gray Rami Intermesenteric (aortic) plexus White communicantes

Inferior mesenteric ganglion, 1st, 2nd, 3rd lumbar splanchnic nerves artery and plexus Gray rami communicantes Ureter and ureteric plexus Sympathetic trunk and ganglia Superior hypogastric plexus 5th lumbar splanchnic nerve Superior rectal artery and plexus L5 spinal nerve (anterior ramus) Hypogastric nerves Lumbosacral trunk Nerve from inferior hypogastric plexus Gray rami communicantes to sigmoid and descending colon (parasympathetic) S1 spinal nerve (anterior ramus) Sacral splanchnic nerves (sympathetic) Pelvic splanchnic nerves Inferior hypogastric (parasympathetic) (pelvic) plexus

Obturator nerve Sacral plexus and artery Piriformis muscle Ductus deferens and plexus Gluteus maximus muscle and sacro- Vesical plexus tuberous ligament

Rectal plexus (Ischio-)coccygeus muscle and Prostatic plexus sacrospinous ligament

Cavernous nerves Pudendal nerve of penis Levator ani muscle

Inferior anal (rectal) nerve

Perineal nerve

Dorsal nerve of penis

Posterior scrotal nerves

42 Nerves of Pelvic Viscera: Female NEUROANATOMY

Sympathetic trunk Abdominal aorta Peritoneum and L2 ganglion Inferior vena cava Extraperitoneal White and (subserous) gray rami fascia communicantes Common iliac vessels and plexus Lumbar splanchnic Ureter nerves Intermesenteric (aortic) plexus Ovarian artery Gray rami and plexus communicantes Superior hypogastric plexus L5 spinal nerve Sacral promontory Superior Right hypogastric hypogastric plexus nerve (cut) Common iliac artery and plexus Right and left sacral Ureter sympathetic trunks and Internal ganglia iliac artery and plexus Sigmoid colon External Piriformis S1 iliac artery Right and left hypogastric nerves muscle S2 and plexus Uterus Right sympathetic trunk Sacral S3 splanchnic nerves S4 Left hypogastric nerve (sympathetic) Inferior hypogastric (pelvic) plexus S5 Pudendal Uterine (fallopian) tube nerve Ovary

Pelvic Symphyseal surface of pubis splanchnic nerves Urinary bladder (parasympathetic) Vesical plexus

(Ischio-)coccygeus muscle Uterovaginal plexus

Uterus (retracted) Rectal plexus

Rectum (retracted)

43 NEUROANATOMY Median Nerve

Anterior view Note: Only muscles innervated by median nerve shown

Musculocutaneous nerve

Median nerve (C5, 6, 7, 8, T1) Medial Inconstant contribution Cords of Posterior brachial Lateral 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 Palmar branch of median nerve Cutaneous innervation

Abductor pollicis brevis Opponens pollicis Thenar Superficial head of muscles flexor pollicis brevis (deep head supplied by ulnar nerve) Palmar view Communicating branch of median nerve with 1st and 2nd ulnar nerve lumbrical muscles Common palmar digital nerves

Proper palmar digital nerves Dorsal branches to dorsum of middle and distal phalanges

Posterior (dorsal) view

44 Ulnar Nerve NEUROANATOMY

Anterior view Note: Only muscles innervated by ulnar nerve shown Ulnar nerve (C7, 8, T1) (no branches above elbow) 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 Palmar branch

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

Palmaris brevis Adductor pollicis muscle Abductor digiti minimi Flexor digiti minimi brevis Hypothenar muscles Opponens digiti minimi

Common palmar digital nerve

Communicating branch of median nerve with ulnar nerve

Palmar and dorsal interosseous muscles

3rd and 4th lumbrical muscles (turned down)

Proper palmar digital nerves (dorsal digital nerves are from dorsal branch)

Dorsal branches to dorsum of middle and distal phalanges

45 NEUROANATOMY Radial Nerve in Arm and Nerves of Posterior Shoulder

Dorsal scapular nerve (C5) Posterior view

Supraspinatus muscle Suprascapular nerve (C5, 6)

Levator scapulae muscle (supplied Deltoid muscle also by branches from C3 and C4) Teres minor muscle

Axillary nerve (C5, 6)

Rhomboid Superior lateral minor muscle cutaneous nerve of arm

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 Lateral intermuscular septum Lower subscapular nerve (C5, 6)

Posterior cutaneous nerve of arm (branch of radial nerve in axilla) Brachialis muscle (lateral part; remainder of muscle supplied by musculo- Long head cutaneous nerve) Triceps brachii muscle Lateral head Medial head Brachioradialis muscle Triceps brachii tendon

Medial epicondyle Extensor carpi radialis longus muscle Olecranon

Extensor carpi Anconeus muscle radialis brevis muscle Extensor digitorum muscle

Extensor carpi ulnaris muscle

46 Radial Nerve in Forearm NEUROANATOMY

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

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

Superior lateral From axillary nerve 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

Tibial division Common fibular (peroneal) of sciatic nerve division of sciatic nerve

Long head (cut) of biceps femoris muscle Short head of biceps femoris muscle Cutaneous innervation

Adductor magnus muscle (also partially supplied Long head (cut) by obturator nerve) of biceps femoris muscle Semitendinosus muscle

Common fibular Semimembranosus muscle (peroneal) nerve

Tibial nerve Articular branch Posterior cutaneous nerve Articular branch of thigh

Lateral sural Plantaris muscle cutaneous nerve

Medial sural cutaneous nerve Sural communicating branch Common fibular Gastrocnemius muscle (peroneal) nerve via lateral sural cutaneous nerve Sural nerve Medial sural cutaneous nerve Soleus muscle From sciatic nerve Superficial fibular (peroneal) nerve Tibial nerve Sural nerve

Lateral calcaneal Tibial nerve Medial branches via medial calcaneal branches calcaneal branches Lateral dorsal Medial and lateral cutaneous nerve plantar nerves

48 Tibial Nerve NEUROANATOMY

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 From Medial tibial nerve plantar nerve (L4, 5) Plantaris muscle Lateral plantar nerve (S1, 2) Gastrocnemius muscle (cut) Saphenous nerve (L3, 4) Sural nerve Nerve to popliteus muscle (S1, 2) via lateral calcaneal and lateral dorsal Popliteus muscle cutaneous branches

Interosseous nerve of leg Cutaneous innervation of sole

Flexor Lateral calcaneal Soleus muscle (cut and retinaculum branch of sural nerve partly retracted) (cut) Tibial Lateral plantar nerve nerve Flexor digitorum Nerve to abductor longus muscle Medial calcaneal digiti minimi muscle branch Quadratus plantae Medial plantar muscle and nerve Tibialis posterior muscle nerve Abductor digiti Flexor digitorum minimi muscle brevis muscle Deep branch to Flexor hallucis and nerve longus muscle interosseous Abductor hallucis muscles, muscle and nerve 2nd, 3rd and 4th lumbrical muscles Sural nerve (cut) Flexor hallucis brevis muscle and and nerve Adductor hallucis muscle Lateral calcaneal branch 1st lumbrical muscle and Superficial nerve branch to 4th interosseous Medial Common muscle calcaneal branch plantar and digital Flexor digiti minimi nerves brevis muscle Proper Flexor retinaculum (cut) Common and plantar Proper plantar digital digital nerves nerves Lateral dorsal cutaneous nerve

Note: Articular branches not shown

49 NEUROANATOMY Common Fibular (Peroneal) Nerve

Lateral sural cutaneous nerve (phantom) Common fibular (peroneal) 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

Superficial fibular Cutaneous innervation (peroneal) nerve

Branches of lateral Extensor digitorum sural cutaneous nerve longus muscle

Fibularis (peroneus) longus muscle Extensor hallucis longus muscle

Fibularis (peroneus) brevis muscle Lateral sural cutaneous nerve

Medial dorsal cutaneous nerve Superficial fibular (peroneal) nerve

Intermediate dorsal Lateral branch of cutaneous nerve deep fibular (peroneal) nerve to Extensor hallucis brevis and Inferior extensor Extensor digitorum brevis muscles Deep retinaculum (partially cut) fibular (peroneal) Medial branch of nerve deep fibular Lateral dorsal cutaneous nerve (peroneal) nerve (branch of sural nerve) Sural nerve via lateral dorsal Dorsal digital nerves cutaneous branch

50 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: Cerebellum: Efferent Pathways ...... 73 Morphology of Synapses ...... 55 Cutaneous Sensory Receptors...... 74 Synaptic Transmission: Neuromuscular Junction ...... 56 Cutaneous Receptors: Pacinian Corpuscle...... 75 Synaptic Transmission: Visceral Efferent Endings ...... 57 Proprioception and Reflex Pathways: I ...... 76 Synaptic Transmission: Proprioception and Reflex Pathways: II . . . . . 77 Inhibitory Mechanisms ...... 58 Proprioception and Reflex Pathways: III . . . . 78 Synaptic Transmission: Proprioception and Reflex Pathways: IV. . . . . 79 Chemical Synaptic Transmission ...... 59 Sensory Pathways: I...... 80 Synaptic Transmission: Temporal and Spatial Summation ...... 60 Sensory Pathways: II ...... 81 Cerebrospinal Fluid (CSF): Sensory Pathways: III...... 82 Brain Ventricles and CSF Composition . . . . 61 Visual System: Receptors...... 83 Cerebrospinal Fluid (CSF): Visual System: Visual Pathway ...... 84 Circulation of CSF ...... 62 Auditory System: Cochlea ...... 85 Spinal Cord: Ventral Rami...... 63 Auditory System: Pathways ...... 86 Spinal Cord: Membranes and Nerve Roots . . 64 Vestibular System: Receptors ...... 87 Peripheral Nervous System ...... 65 Vestibular System: Vestibulospinal Tracts. . . . 88 Autonomic Nervous System: Schema...... 66 Gustatory (Taste) System: Receptors ...... 89 Autonomic Nervous System: Cholinergic and Adrenergic Synapses . . . . . 67 Gustatory (Taste) System: Pathways ...... 90 Hypothalamus ...... 68 Olfactory System: Receptors ...... 91 Limbic System ...... 69 Olfactory System: Pathway ...... 92 NEUROPHYSIOLOGY Organization of the Brain: Cerebrum

Central sulcus (Rolando) Postcentral gyrus 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) ©

FIGURE 2.1 ORGANIZATION OF THE BRAIN: CEREBRUM• The cerebral cortex represents the highest center for sensory and coordinates smooth motor activities and processes muscle position. motor processing. In general, the frontal lobe processes motor, The brainstem (medulla, pons, midbrain) conveys motor and sensory visual, speech, and personality modalities. The parietal lobe information and mediates important autonomic functions. The spinal processes sensory information; the temporal lobe, auditory and cord receives sensory input from the body and conveys somatic and memory modalities; and the occipital lobe, vision. The cerebellum autonomic motor information to peripheral targets (muscles, viscera).

52 Organization of the Brain: Cell Types NEUROPHYSIOLOGY

Multipolar (pyramidal) Bipolar cell of cranial n. cell of cerebral Unipolar cell of motor cortex sensory ganglia of cranial nn. Satellite cells Astrocyte Schwann cell Striated Interneurons (somatic) Blood vessel Free nerve endings muscle (unmyelinated fibers) Encapsulated ending Motor endplate Specialized ending Multipolar somatic Muscle spindle motor cell of nuclei Unipolar sensory cell of cranial nn. of dorsal spinal Multipolar cell root ganglion Interneuron of lower brain Satellite cells motor centers Oligodendrocyte Astrocyte Myelinated afferent Corticospinal fiber of spinal nerve (pyramidal) fiber Multipolar visceral Axodendritic ending motor (autonomic) cell of spinal cord Axosomatic ending Myelin sheath Axoaxonic ending Autonomic preganglionic Multipolar somatic (sympathetic or para- Red: Motor neuron motor cell of sympathetic) nerve fiber Blue: Sensory neuron anterior horn Myelin sheath Purple: Interneuron of spinal cord Gray: Glial and Autonomic postganglionic neurilemmal cells Collateral neuron of sympathetic or and myelin parasympathetic ganglion Note: Cerebellar cells Renshaw interneuron Satellite cells (feedback) not shown here Unmyelinated nerve fiber Myelinated somatic motor Schwann cells fiber of spinal nerve

Myelin sheath Schwann cells

Motor endplate with Endings on Unmyelinated fibers Schwann cell cap cardiac muscle or nodal cells Striated Free nerve endings (voluntary) Beaded muscle varicosities and endings on Encapsulated ending smooth muscle and gland cells Muscle spindle ©

FIGURE 2.2 ORGANIZATION OF THE BRAIN: CELL TYPES• Neurons form the functional cellular units responsible for (e.g., astrocytes, oligodendrocytes), satellite cells, and other spe- communication, and throughout the nervous system, they are cialized cells that optimize neuronal function, provide mainte- characterized by their distinctive size and shapes (e.g., bipolar, nance functions, or protect the nervous system. unipolar, multipolar). Supporting cells include the neuroglia

53 NEUROPHYSIOLOGY Blood-Brain Barrier

Cell membrane Basement Tight membrane junction proteins

Cytoplasm

Red blood cell

Astrocyte Capillary foot processes lumen

Tight Capillary junction endothelial cell Astrocyte

©

FIGURE 2.3 BLOOD-BRAIN BARRIER• The blood-brain barrier (BBB) is the cellular interface between the other substances (including many drugs) from the blood to the blood and the central nervous system (CNS; brain and spinal cord). interstitial space of the CNS is restricted by the BBB. CNS endothe- It serves to maintain the interstitial fluid environment to ensure lial cells also exhibit a low level of pinocytotic activity across the optimal functionality of the neurons. This barrier consists of the cell, so specific carrier systems for the transport of essential sub- capillary endothelial cells with an elaborate network of tight junc- strates of energy and amino acid metabolism are characteristic of tions and astrocytic foot processes that abut the endothelium and these cells. The astrocytes help transfer important metabolites from its basement membrane. The movement of large molecules and the blood to the neurons and also remove excess Kϩ and neuro- transmitters from the interstitial fluid. 54 Synaptic Transmission: Morphology of Synapses NEUROPHYSIOLOGY

Dendrite

Node Axon

Dendrites Myelin sheath

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

Enlarged section of bouton

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 lower figure shows an enlargement of one such synaptic bouton. specialized regions called synapses. The top figure shows a typical Chemical neurotransmitters are contained in synaptic vesicles, motor neuron that receives numerous synaptic contacts on its cell which can fuse with the presynaptic membrane, release the trans- body and associated dendrites. Incoming axons lose their myelin mitters into the synaptic cleft, and then bind to receptors situated sheaths, exhibit extensive branching, and terminate as synaptic in the postsynaptic membrane. This synaptic transmission results in boutons (synaptic terminals or knobs) on the motor neuron. The excitatory, inhibitory, or modulatory effects on the target cell.

55 NEUROPHYSIOLOGY Synaptic Transmission: Neuromuscular Junction

Structure of Neuromuscular Junction

Active zone Myelin sheath Schwann cell process Neurilemma Axoplasm Acetylcholine Schwann cell receptor sites 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 termi- ately stimulated, release their neurotransmitter into the synaptic nals called neuromuscular junctions (motor endplates). The motor cleft. The transmitter then binds to receptors that mediate depolar- axon loses its myelin sheath and expands into a Schwann ization of the muscle sarcolemma and initiate a muscle action cell–invested synaptic terminal that resides within a trough in the potential. A single muscle fiber has only one neuromuscular junc- muscle fiber. Acetylcholine-containing synaptic vesicles accumu- tion, but a motor axon can innervate multiple muscle fibers. late adjacent to the presynaptic membrane and, when appropri-

56 Synaptic Transmission: Visceral Efferent Endings NEUROPHYSIOLOGY

Visceral Efferent Endings                      A. Smooth muscle B. Gland (submandibular) C. Neurosecretory (posterior pituitary) Sympathetic terminal ending Pituicyte processes Mucous cells Smooth muscle cells (cut) Varicosity Axon Axon Schwann cell Schwann Schwann cell cap enclosing cap enclosing cell cap nerve axons nerve axons

Fibroblast Schwann cell cap Capillary Neurosecretory Serous cells Schwann cell Smooth muscle cells cap enclosing vesicles Endothelium Varicosities Parasympathetic nerve axons terminal ending Collagen space Terminal endings Mast cell Varicosity Basement membrane

©

FIGURE2.6VISCERALEFFERENTENDINGS• Neuronal efferent endings on smooth muscle (A) and glands (B rosecretion) from expanded nerve terminal endings. This arrange- and C) exhibit unique endings unlike the presynaptic and postsy- ment allows for the stimulation of numerous target cells over a naptic terminals observed in neuronal and neuromuscular junc- wide area. Not all smooth muscle cells are innervated. They are tion synapses. Rather, neurotransmitter substances are released connected to adjacent cells by gap junctions and can therefore into interstitial spaces (A and B) or into the bloodstream (C, neu- contract together with the innervated cells.

57 NEUROPHYSIOLOGY Synaptic Transmission: Inhibitory Mechanisms

I E E (Inhibitory (Excitatory (Excitatory fiber) fiber) fiber)

Motor neuron Motor neuron

I Axon (Inhibitory Axon fiber)

mV ϩ20 mV A. Only E fires 90-mV spike 90 mV A . Only E fires in E terminal ′ Ϫ70 EPSP in Ϫ60 motor Ϫ60 EPSP in neuron motor neuron Ϫ70 Ϫ70

B. Only I fires B′. Only I fires Long-lasting partial Ϫ60 Motor depolarization Ϫ70 neuron in E terminal hyper- Ϫ70 No response in polarized Ϫ80 motor neuron Ϫ70

C. I fires before E C′. I fires before E Partial Ϫ60 depolarization Depolariza- ϩ20 of E terminal tion of motor Ϫ70 reduces spike neuron less 80 mV to 80 mV, thus than if only Ϫ80 releasing less E fires transmitter Ϫ70 substance Ϫ60 Smaller EPSP in motor neuron Ϫ 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 Synaptic Transmission: Chemical Synaptic Transmission NEUROPHYSIOLOGY               Excitatory Inhibitory Synaptic vesicles in synaptic bouton Presynaptic membrane Transmitter Na substances Synaptic cleft Cl K Postsynaptic membrane

When impulse reaches excitatory synaptic At inhibitory synapse, transmitter substance re- bouton, it causes release of a transmitter leased by an impulse increases permeability of substance into synaptic cleft. This increases the postsynaptic membrane to Cl. K moves permeability of postsynaptic membrane to out of post-synaptic cell but no net flow of Cl Na and K. More Na moves into postsy- occurs at resting membrane potential naptic cell than K moves out, due to great- er electrochemical gradient

Synaptic bouton

Resultant net ionic current flow is in a direc- Resultant ionic current flow is in direction that tends to tion that tends to depolarize postsynaptic cell. hyperpolarize postsynaptic cell. This makes depolariza- If depolarization reaches firing threshold, an tion by excitatory synapses more difficult—more depolari- impulse is generated in postsynaptic cell zation is required to reach threshold msec Current 04812 16 70 65 Potential Potential

75 otential (mV) otential (mV) Current P P 70 04812 16 msec

Current flow and potential change Current flow and potential change ©

FIGURE2.8CHEMICALSYNAPTICTRANSMISSION• Chemical synaptic transmission between neurons may be excita- threshold for an action potential. During inhibition (right column), tory or inhibitory. During excitation (left column), a net increase in the opening of Kand Clchannels drives the membrane potential the inward flow of Nacompared with the outward flow of K away from threshold (hyperpolarization) and decreases the proba- results in a depolarizing potential change (excitatory postsynaptic bility that the neuron will reach threshold (inhibitory postsynaptic potential [EPSP]) that drives the postsynaptic cell closer to its 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 Excitatory fibers mV

–70 –70

Axon Axon

Inhibitory fibers Inhibitory fibers A. Resting state: motor nerve cell shown with synaptic boutons of B. Partial depolarization: impulse from one excitatory fiber has excitatory and inhibitory nerve fibers ending close to it caused partial (below firing threshold) depolarization of motor neuron

Excitatory fibers mV Excitatory fibers mV –70 –70

Axon Axon Inhibitory fibers Inhibitory fibers C. Temporal excitatory summation: a series of impulses in one D. Spatial excitatory summation: impulses in two excitatory fibers excitatory fiber together produce a suprathreshold depolarization cause two synaptic depolarizations that together reach firing that triggers an action potential threshold triggering an action potential

Excitatory fibers mV Excitatory fibers mV –70 –70

Axon Axon

Inhibitory fibers Inhibitory fibers E. Spatial excitatory summation with inhibition: impulses from E. (continued): motor neuron now receives additional excitatory two excitatory fibers reach motor neuron but impulses from impulses and reaches firing threshold despite a simultaneous inhibitory fiber prevent depolarization from reaching threshold 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 Location Transmitter Location Acetylcholine Neuromuscular junction, autonomic end- Gas ings and ganglia, CNS Nitric oxide CNS, GI tract Biogenic amines Peptides Norepinephrine Sympathetic endings, CNS ␤-Endorphins CNS, GI tract Dopamine CNS Enkephalins CNS Serotonin CNS, GI tract Antidiuretic CNS (hypothalamus/posterior Amino acids hormone pituitary) ␥-Aminobutyric CNS Pituitary-releasing CNS (hypothalamus/anterior acid (GABA) hormones pituitary) Glutamate CNS Somatostatin CNS, GI tract Purines Neuropeptide Y CNS Adenosine CNS Vasoactive Adenosine CNS intestinal peptide CNS, GI tract triphosphate (ATP)

CNS, Central nervous system; GI, gastrointestinal.

FIGURE 2.9 TEMPORAL AND SPATIAL SUMMATION • Neurons receive multiple excitatory and inhibitory inputs. Tempo- tial (panel D). Both temporal and spatial summation can be modu- ral summation occurs when a series of subthreshold impulses in lated by simultaneous inhibitory input (panel E). Inhibitory and one excitatory fiber produces an action potential in the postsynap- excitatory neurons use a wide variety of neurotransmitters, some of tic cell (panel C). Spatial summation occurs when subthreshold which are summarized here. impulses from two or more different fibers trigger an action poten-

60 Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition NEUROPHYSIOLOGY

Left lateral phantom view Right lateral ventricle Frontal (anterior) horn Central part Left lateral Temporal (inferior) horn 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

CSF Blood Plasma Naϩ (mEq/L) 140–145 135–147 Kϩ (mEq/L) 3 3.5–5.0 Cl− (mEq/L) 115–120 95–105 − HCO3 (mEq/L) 20 22–28 Glucose (mg/dL) 50–75 70–110 Protein (g/dL) 0.05–0.07 6.0–7.8 pH 7.3 7.35–7.45

FIGURE 2.10 BRAIN VENTRICLES AND CSF COMPOSITION• Ϫ CSF circulates through the four brain ventricles (two lateral ventri- secretes the CSF. Importantly, the CSF has a lower [HCO3 ] than cles and a third and fourth ventricle) and in the subarachnoid plasma and therefore a lower pH. This allows small changes in space surrounding the brain and spinal cord. The electrolyte com- blood PCO2 to cause changes in CSF pH, which in turn regulates position of the CSF is regulated by the choroid plexus, which the rate of respiration (see Chapter 5).

61 NEUROPHYSIOLOGY Cerebrospinal Fluid (CSF): Circulation of CSF

Choroid plexus of lateral ventricle (phantom) Superior sagittal sinus

Cistern of corpus callosum Subarachnoid space 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 Median aperture (foramen of Magendie) Dura mater

Arachnoid

Subarachnoid space

Central canal of spinal cord

©

FIGURE 2.11 CIRCULATION OF CEREBROSPINAL FLUID• CSF circulates through the four brain ventricles (two lateral ventri- reabsorbed into the venous system through the arachnoid granula- cles and a third and fourth ventricle) and in the subarachnoid tions and through the walls of the capillaries of the central nervous space surrounding the brain and spinal cord. Most of the CSF is system and pia mater.

62 Spinal Cord: Ventral Rami NEUROPHYSIOLOGY

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 Intercostal (T7 and T8) nerves

T12 spinal nerve

L1 12th rib vertebra

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 fibers of these spinal nerves innervate skeletal muscle, and sensory segmentally to the body. These nerves are organized into plexuses fibers convey information back to the central nervous system from that distribute to the neck (cervical plexus), upper limb (brachial the skin, skeletal muscles, and joints. plexus), and pelvis and lower limb (lumbosacral plexus). Motor

63 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 The spinal cord is ensheathed in three meningeal coverings: the segmentally to the body. Motor fibers of these spinal nerves inner- outer, tough dura mater; the arachnoid mater; and the pia mater, vate skeletal muscle, and sensory fibers convey information back which intimately ensheaths the cord itself. CSF bathes the cord and to the central nervous system from the skin, skeletal muscles, and is found in the subarachnoid space. joints.

64 Peripheral Nervous System NEUROPHYSIOLOGY

Posterior horn Dorsal root ganglion

Sensory neuron cell body

Dorsal root

Anterior horn Motor neuron cell body Ventral root

Peripheral nerve

Axon

Myelin sheath

Motor neuron Sensory neuron

Neuromuscular junction Skin

Muscle

with

©

FIGURE 2.14 PERIPHERAL NERVOUS SYSTEM• The peripheral nervous system (PNS) consists of all of the neural shown here (see Figure 2.15 for the autonomic nervous system). elements outside of the CNS (brain and spinal cord) and provides The somatic component of the peripheral nerves contains both the connections between the CNS and all other body organ sys- motor and sensory axons. Cell bodies of the motor neurons are tems. The PNS consists of somatic and autonomic components. The found in the anterior horn gray matter, whereas the cell bodies of somatic component innervates skeletal muscle and skin and is sensory neurons are located in the dorsal root ganglia.

65 NEUROPHYSIOLOGYAutonomic Nervous System: Schema

Oculomotor nerve (III) Intracranial vessels Facial nerve (VII) Ciliary ganglion Eye Glossopharyngeal nerve (IX) Pterygopalatine ganglion Medulla oblongata Lacrimal glands Vagus nerve (X) Otic ganglion Parotid glands C1 Submandibular ganglion C2 Sublingual and submandibular glands C3 C4 Peripheral cranial

Gray rami Gray and facial vessels C5 communicantes C6 Larynx C7 Trachea C8 Bronchi Lungs Sweat T1 gland T2 Pulmonary plexus

T3 s e Heart t Cardiac plexus T4 n a Greater  Splanchnic Peripheral c T5 i Lesser nerves blood vessel n  Celiac ganglion T6 u Least  m Stomach m

T7 o Aorticorenal ganglion

c

i Liver

T8 m a Gallbladder

r

e Bile ducts

t i

T9 h w Lumbar

d Pancreas

n splanchnic Superior mesenteric

T10 a

y nerves ganglion a Suprarenal glands

T11 r G Arrector (smooth) Kidneys T12 Inferior mesenteric muscle of hair follicle ganglion Note: Above three L1 structures are shown at Intestines only one level but L2 Superior hypogastric occur at all levels L3 plexus

s

L4 e Descending colon t

n

a L5 c Sigmoid colon i

n Note: Blue-shaded S1 u Rectum m Inferior areas indicate zones of m o hypogastric parasympathetic S2 c Urinary bladder i plexus outflow from CNS m S3 a r S4 y Pelvic a Prostate S5 r splanchnic G Coccygeal nerves External genitalia

© Presynaptic Presynaptic Sympathetic Parasympathetic Antidromic fibers Postsynaptic fibers Postsynaptic conduction

FIGURE2.15AUTONOMICNERVOUSSYSTEM: SCHEMA• The autonomic nervous system is composed of two divisions: the a peripheral autonomic ganglion. Postganglionic axons of the auto- parasympathetic division derived from four of the cranial nerves nomic nervous system innervate smooth muscle, cardiac muscle, and (CN III, VII, IX, and X) and the S2-S4 sacral spinal cord levels, and the glands. Basically, the sympathetic division mobilizes our body (“fight sympathetic division associated with the thoracic and upper lumbar or flight”) while the parasympathetic division regulates digestive and spinal cord levels (T1-L2). The autonomic nervous system is a two- homeostatic functions. Normally, both divisions work in concert to neuron chain, with the preganglionic neuron arising from the central regulate visceral activity (respiration, cardiovascular function, diges- nervous system and synapsing on a postganglionic neuron located in tion, and associated glandular activity). 66 Autonomic Nervous System: Cholinergic and Adrenergic Synapses NEUROPHYSIOLOGY

Parotid Glossopharyngeal gland nerve (IX) Larynx Medulla Internal carotid nerve Trachea oblongata Bronchi Lungs Vagus nerve (X)

Heart Cervical sympathetic ganglia Striated muscle

Sweat glands

White ramus Hair follicles Thoracic Gray ramus communicans part of communicans Celiac spinal cord ganglion Peripheral arteries

Superior mesenteric Visceral Upper ganglion arteries lumbar part of Gastrointestinal spinal cord tract (L1-2 [3]) Suprarenal gland

Inferior mesenteric ganglion

Sacral Pelvic splanchnic nerves part of Urinary bladder spinal cord C Cholinergic synapses Urethra Prostate A Adrenergic synapses

Presynaptic Presynaptic Sympathetic Parasympathetic fibers Postsynaptic fibers Postsynaptic

Somatic fibers Antidromic conduction ©

FIGURE 2.16 CHOLINERGIC AND ADRENERGIC SYNAPSES: SCHEMA• The autonomic nervous system (ANS) is a two-neuron chain, with aline (norepinephrine) at its postganglionic synapses, causing the preganglionic neuron arising from the central nervous system adrenergic (A) effects (except on sweat glands, where acetylcholine and synapsing on a postganglionic neuron located in a peripheral is released). Although acetylcholine and noradrenaline are the autonomic ganglion. Acetylcholine is the neurotransmitter in both chief transmitter substances, other neuroactive peptides often are the sympathetic and parasympathetic ganglia. The parasympathetic colocalized with them and include such substances as gamma- division of the ANS releases acetylcholine at its postganglionic aminobutyric acid (GABA), substance P, enkephalins, histamine, synapses and is characterized as having cholinergic (C) effects, glutamic acid, neuropeptide Y, and others. whereas the sympathetic division releases predominantly noradren- 67 NEUROPHYSIOLOGY Hypothalamus

Corpus callosum Septum Fornix pellucidum Lateral ventricle

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

Olfactory tract

Fornix Cerebral Red nucleus peduncle Ventromedial nucleus Mamillary Optic (II) complex nerve Tuberohypophyseal tract Dorsal Optic chiasm longitudinal Oculomotor (III) nerve fasciculus Supraoptic nucleus Descending hypothalamic Supraopticohypophyseal connections tract Pons Posterior lobe of pituitary Anterior Reticular lobe of formation pituitary © CHART 2.3 MAJOR FUNCTIONS OF THE HYPOTHALAMUS

Hypothalamic Area Major Functions* Preoptic and anterior Heat loss center: cutaneous vasodilation and sweating Posterior Heat conservation center: cutaneous vasoconstriction and shivering Lateral Feeding center: eating behavior Ventromedial Satiety center: inhibits eating behavior Supraoptic (subfornical organ and organum vasculosum) ADH and oxytocin secretion (sensation of thirst) Paraventricular ADH and oxytocin secretion Periventricular 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 information), the thalamus (pain), the limbic system (emotion, fear, important homeostatic systems within the body, including tempera- anger, smell), the medulla oblongata (blood pressure and heart ture regulation, food intake, water intake, many of the endocrine rate), and the optic system, and it integrates these inputs for regula- systems (see Chapter 8), motivation, and emotional behavior. It tion of the functions listed. receives inputs from the reticular formation (sleep/wake cycle

68 Limbic System NEUROPHYSIOLOGY

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 Hippocampus Amygdaloid bodies with fimbria ©

FIGURE 2.18 HIPPOCAMPUS AND FORNIX• The limbic system includes the hypothalamus and a collection of pocampal formation. The limbic system functions in linking emo- interconnected structures in the telencephalon (cingulate, parahip- tion and motivation (amygdala), learning and memory (hippocam- pocampal, and subcallosal gyri), as well as the amygdala and hip- pal formation), and sexual behavior (hypothalamus).

69 NEUROPHYSIOLOGY The Cerebral Cortex

Ms I Sm I Motor Sensory Premotor; orientation; Ms II Sm II eye and head Sensory movements analysis

Prefrontal; inhibitory control of behavior; higher intelligence Visual III

Visual II

Visual I

Motor control Language; of speech reading; speech Auditory I Auditory II

Ms I Sm I Motor Sensory Ms II Sm III Premotor ? Prefrontal; inhibitory control of behavior; higher intelligence Visual III

Visual II

Visual I

Cingulate gyrus © (emotional behavior) Corpus callosum and cingulum Hippocampal commissure Olfactory Anterior commissure

FIGURE 2.19 CEREBRAL CORTEX: LOCALIZATION OF FUNCTION AND ASSOCIATION PATHWAYS• The cerebral cortex is organized into functional regions. In addi- including aspects of memory storage and recall, language, higher tion to specific areas devoted to sensory and motor functions, there cognitive functions, conscious perception, sensory integration, and are areas that integrate information from multiple sources. The planning/execution of complex motor activity. General cortical cerebral cortex participates in advanced intellectual functions, areas associated with these functions are illustrated.

70 Descending Motor Pathways NEUROPHYSIOLOGY

Motor Hip

cortex Knee runk

T rist Ankle Elbow W Shoulder Fingers Internal Thumb Toes capsule Neck Brow Eyelid Nares Lips Lateral aspect of cerebral cortex to show Tongue Larynx topographic projection of motor centers on precentral gyrus

Midbrain

Motor system Basis pedunculi Fibers originate in motor cortex and descend via posterior limb of internal capsule to basis pedunculi of midbrain Pons Longitudinal bundles branch upon entering basis pontis and rejoin to Basis enter pyramids of medulla pontis At lower medulla, bulk of fibers cross median plane to form lateral corticospinal tract; some fibers Medulla continue downward in ipsilateral lateral corticospinal tract; others descending ipsilateral anterior Pyramids corticospinal tract Synapse occurs at spinal level: Lateral corticospinal fibers synapse on ipsilateral anterior horn cells; anterior Medulla corticospinal fibers synapse on contralateral anterior horn cells Decussation of pyramids Above mid- thoracic level Motor endplate

Spinal Anterior corticospinal tract cord Below mid- thoracic Lateral corticospinal tract level Motor endplate ©

FIGURE 2.20 CORTICOSPINAL TRACTS• The corticospinal, or pyramidal, tract is the major motor tract that cord constitute the upper portion of the system (upper motor neu- controls voluntary movement of the skeletal muscles, especially ron). The anterior horn cells and their associated axons constitute skilled movements of distal muscles of the limbs. All structures the lower portion of the system (lower motor neuron). from the cerebral cortex to the anterior horn cells in the spinal

71 NEUROPHYSIOLOGY Cerebellum: Afferent Pathways

Superior cerebellar peduncle Middle cerebellar peduncle

To contralateral cerebellar cortex Cortical input Leg Nucleus Arm reticularis Face Primary fissure tegmenti pontis Pontine nuclei (contralateral) Spinal input Inferior olive Upper part of medulla To nodule and flocculus oblongata Vestibular Inferior cerebellar peduncle Spinal input nuclei Functional Subdivisions of Cerebellum Hemisphere Vermis Reticulocerebellar Inter- tract Lateral mediate Vestibular nerve Cuneocerebellar part part Anterior lobe and ganglion tract Leg zone Primary Lower part Gracile nucleus Arm zone fissure of medulla Face zone Main cuneate oblongata nucleus (relay Middle Cortical input for cutaneous (posterior) 2nd spinal information) lobe Lateral reticular projection nucleus External cuneate nucleus area (gracile (relay for proprioceptive lobule) Posterolateral Spinal input information) fissure Archi- Cervical part From skin (touch cerebellum Lingula Flocculo- of spinal cord and pressure) (vestibulo- Flocculus nodular lobe Motor interneuron From muscle (spindles cerebellum) Nodule Uvula and Golgi tendon organs) Paleocerebellum Rostral Pyramid From skin and (spinocerebellum) spinocerebellar Vermis deep tissues tract Neocerebellum Middle vermis (pain and Golgi (pontocerebellum) Hemisphere Spinal border cells tendon organs) Schema of Motor interneuron From skin (touch theoretical Lumbar part and pressure) “unfolding” of spinal cord and from muscle of cerebellar (spindles and surface in Clarke’s column Golgi tendon derivation of Ventral spino- organs) above diagram cerebellar tract Dorsal spinocerebellar tract

© FIGURE 2.21 CEREBELLAR AFFERENT PATHWAYS• The cerebellum plays an important role in coordinating movement. It bellum primarily controls movement of the proximal portions of the receives sensory information and then influences descending motor limbs. It receives sensory information on limb position and muscle pathways to produce fine, smooth, and coordinated motion. The tone and then modifies and coordinates these movements through cerebellum is divided into three general areas: archicerebellum (also efferent pathways to the appropriate descending motor pathways. The called vestibulocerebellum) paleocerebellum (also called spinocere- neocerebellum is the largest portion of the cerebellum, and it coordi- bellum) and the neocerebellum (also called the cerebrocerebellum). nates the movement of the distal portions of the limbs. It receives The archicerebellum is primarily involved in controlling posture and input from the cerebral cortex and thus helps in the planning of balance, as well as the movement of the head and eyes. It receives motor activity (e.g., seeing a pencil and then planning and executing afferent signals from the vestibular apparatus and then sends efferent the movement of the arm and hand to pick it up). fibers to the appropriate descending motor pathways. The paleocere- 72 Cerebellum: Efferent Pathways NEUROPHYSIOLOGY

Excitatory endings Motor and Inhibitory premotor endings of cerebral Purkinje cortex cells

Ventral anterior and Internal capsule ventral lateral nuclei of thalamus Cerebral peduncle Mesencephalic reticular formation Decussation of superior cerebellar peduncles Red nucleus Descending fibers from Fastigial nucleus superior cerebellar peduncles Globose nuclei Hook bundle of Russell Emboliform nucleus

Dentate nucleus Section A–B Cerebellar viewed cortex from below

Section B–C viewed from above Vestibular nuclei Inferior cerebellar peduncle A Planes of Inferior olive section: B Lateral reticular nucleus red arrows indicate Medulla oblongata C direction Pontomedullary reticular formation of view ©

FIGURE 2.22 CEREBELLAR EFFERENT PATHWAYS• The cerebellum plays an important role in coordinating movement. the proximal portions of the limbs. It modifies and coordinates It influences descending motor pathways to produce fine, smooth, these movements through efferent pathways to the appropriate and coordinated motion. The archicerebellum is primarily involved descending motor pathways. The neocerebellum coordinates the in controlling posture and balance and movement of the head and movement of the distal portions of the limbs. It helps in the plan- eyes. It sends efferent fibers to the appropriate descending motor ning of motor activity (e.g., seeing a pencil and then planning and pathways. The paleocerebellum primarily controls movement of executing the movement of the arm and hand to pick it up).

73 NEUROPHYSIOLOGY Cutaneous Sensory Receptors

Free nerve endings Meissner’s corpuscle Stratum corneum Hair shaft Pore of sweat gland Stratum

pdri emsSubcutaneous tissue lucidum Dermis Epidermis Melanocyte Stratum granulosum Arrector muscle of hair Sebaceous gland Stratum Cuticle spinosum Stratum Internal sheath basale External sheath

Glassy Dermal

Hair follicle membrane papilla (of papillary Connective layer) tissue layer

Reticular layer Hair cuticle

Sweat gland

Hair matrix

Papilla of hair follicle

Pacinian corpuscle Artery Subcutaneous Vein artery and vein Sensory nerves Basement membrane Elastic fibers Axon terminal Cutaneous Detail of Merkel’s disc Mitochondrion Skin ligaments nerve (retinacula cutis) Schwann cell Motor (autonomic) Basal nerve epithelial Desmosomes Cross section cells

Merkel Cytoplasmic cell protrusion Lobulated Mitochondria nucleus

Granulated Expanded vesicles © axon terminal Axon Schwann cells Schwann cell Detail of free nerve ending

FIGURE 2.23 SKIN AND CUTANEOUS RECEPTORS• Cutaneous receptors respond to touch (mechanoreceptors), pain respond best to high-frequency stimulation (i.e., vibration). (nociceptors), and temperature (thermoreceptors). Several different Merkel’s discs have small receptive fields and respond to touch and types of receptors are present in skin. Meissner’s corpuscles have pressure (i.e., indenting the skin). Ruffini’s corpuscles have large small receptive fields and respond best to stimuli that are applied receptive fields, and they also respond to touch and pressure. Free at low frequency (i.e., flutter). The pacinian corpuscles are located nerve endings respond to pain and temperature. in the subcutaneous tissue and have large receptive fields. They

74 Cutaneous Receptors: Pacinian Corpuscle NEUROPHYSIOLOGY

Pacinian Corpuscle as Pressure Transducer Pressure To amplifier

Generator potential

Action potential

1st node A. Sharp “on and off” changes in pressure at start and end of pulse applied to lamellated capsule are transmitted to Myelin sheath central axon and provoke generator potentials, which in Lamellated capsule turn may trigger action potentials; there is no response to a slow change in pressure gradient. Pressure at central core Central core and, accordingly, generator potentials are rapidly dissipated by viscoelastic properties of capsule (Action potentials may Unmyelinated axon terminal be blocked by pressure at a node or by drugs)

Pressure To amplifier

Generator potential

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

؉

Pressure applied to axon terminal directly or via capsule causes increased permeability of membrane to Na+, thus setting up ionic generator current through 1st node ؉ ؉ ؉ ؉ ؉ ؉ ؉ ؉ ؉ ؊ ؉ ؉ ؉ ؊ ؊ ؊ ؊ ؊ ؊ ؊ ؊ ؊ ؉ ؊ ؊ ؊؊؊

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

FIGURE 2.24 PACINIAN CORPUSCLE• Pacinian corpuscles are mechanoreceptors that transduce mechani- producing a “generator potential.” As demonstrated in the figure, cal forces (displacement, pressure, vibration) into action potentials pacinian corpuscles respond to the beginning and end of a that are conveyed centrally by afferent nerve fibers. As the vis- mechanical force while the concentric lamellae dissipate slow coelastic lamellae are displaced, the unmyelinated axon terminal changes in pressure. In the absence of the capsule, the generator membrane’s ionic permeability is increased until it is capable of 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 Proprioceptive fibers cutaneous Dorsal horn interneuron receptor From muscle spindle

Dorsal root ganglion Flexor reflex interneuron Ventral root To motor neuron Dorsal horn interneuron

To motor neuron ␣ motor axon

Schematic representation of motor neurons

In cervical enlargement of spinal cord

In lumbar enlargement Fle s x ors of spinal cord or Fle x s s r r o so s E en n xt Exte

©

FIGURE 2.25 PROPRIOCEPTION: SPINAL EFFECTOR MECHANISM• Position sense or proprioception involves input from cutaneous panel) initiate muscle contraction reflexes. The lower panel shows mechanoreceptors, Golgi tendon organs, and muscle spindles the somatotopic distribution of the motor neuron cell bodies in the (middle figure of upper panel). Both monosynaptic reflex pathways ventral horn of the spinal cord that innervate limb muscles (flexor (middle figure of upper panel) and polysynaptic pathways involv- and extensor muscles of upper and lower limbs). ing several spinal cord segments (top and bottom figures of upper

76 Proprioception and Reflex Pathways: II NEUROPHYSIOLOGY

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 A␦ and C fibers from free nerve endings Alpha motor neuron to extrafusal muscle fiber end plates Gamma motor neuron to intrafusal muscle fiber and plates II (A␤) fiber from flower spray endings Extrafusal Ia (A␣) fiber from annulospiral endings muscle fiber Intrafusal muscle fibers Sheath Lymph space Nuclear bag fiber Nuclear chain fiber ©

Detail of Efferent fibers muscle spindle Afferent fibers

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

77 NEUROPHYSIOLOGY Proprioception and Reflex Pathways: III

Ib fibers

Ia fibers ϩϩϩϩ

Extrafusal muscle fiber

Intrafusal muscle fiber

Alpha motor neurons ϩϩϩ

Gamma motor neurons

A. Passive stretch. Both intrafusal and extrafusal muscle fibers stretched; Golgi spindles activated. Reflex via Ia fibers and alpha motor neurons causes tendon secondary contraction (basis of stretch reflexes, such as knee jerk). organ Stretch is too weak to activate Golgi tendon organs Ib fibers ϩϩ Alpha activation from brain Ia fibers

Extrafusal muscle fiber Intrafusal muscle fiber Inhibitory interneuron

Alpha motor neurons ϩϩ

Gamma motor neurons

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; Golgi does not adjust to increased resistance. Tendon organ activated, tendon causing relaxation organ Alpha and Ib fibers ϩϩϩ gamma activation from brain Ia fibers ϩϩϩϩ

Extrafusal muscle fiber

Intrafusal muscle fiber

Alpha motor neurons ϩϩϩϩ

Gamma motor neurons ϩϩϩϩ

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

FIGURE 2.27 PROPRIOCEPTIVE REFLEX CONTROL OF MUSCLE TENSION• Interaction of the muscle spindle and Golgi tendon organ during passive stretch of a muscle (panel A) and during a contraction (panels B and C).

78 Proprioception and Reflex Pathways: IV NEUROPHYSIOLOGY

B. Stretch reflex A. Afferent inhibition (reciprocal 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 Contralateral flexion extension

Inhibitory synapse Excitatory synapse

Excitatory synapse Inhibitory synapse

To extensors To extensors To flexors 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 Large Cervical part Touch, myelinated of spinal cord pressure, fibers vibration Small Lateral Pain, myelinated spinothalamic tract: temperature and unmyelin- pain, temperature ated fibers Lateral cervical nucleus Ventral (anterior) spinothalamic tract: Spinocervical tract touch, pressure

Lumbar part

of spinal cord ©

FIGURE 2.29 SOMESTHETIC SYSTEM OF THE BODY• Pain, temperature, and pressure sensations below the head ulti- sations to the thalamus (ventral posterolateral nucleus), whereas mately are conveyed to the primary somatosensory cortex (post- the lateral cervical system mediates some touch, vibratory, and central gyrus) by the anterolateral system (spinothalamic and spin- proprioceptive sensations (blue and purple lines show these dual oreticular tracts). The fasciculus gracilis and cuneatus of the spinal pathways). Ultimately, these fibers ascend as parallel pathways to lemniscal system convey proprioceptive, vibratory, and tactile sen- the thalamus, synapse, and ascend to the cortex.

80 Sensory Pathways: II NEUROPHYSIOLOGY

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

Midbrain (cerebral Dorsal trigeminal lemniscus peduncles) Trigeminal mesencephalic nucleus Ventral Trigeminal motor nucleus trigeminal Principal sensory trigeminal nucleus lemniscus Touch, pressure Pontine Pain, temperature reticular formation Proprioception 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 Facial (VII) n. cord 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 of CN V (purple fibers). Most relay neurons project to the con- the head are in the trigeminal (semilunar) ganglion of the trigemi- tralateral VPM nucleus of the thalamus and thence to the postcen- nal (CN V) nerve (blue and red lines in figure). Neuronal cell bod- tral gyrus of the cerebral cortex, where they are somatotopically ies mediating proprioception reside in the mesencephalic nucleus represented.

81 NEUROPHYSIOLOGY Sensory Pathways: III

Schematic demarcation of dermatomes shown as distinct C2 segments. There is actually considerable overlap between C3 C2 any two adjacent dermatomes C4 C5 C3 C6 C4 C7 C5 C8 T1 T1 T2 T2 T3 T3 T4 C6 C6 T5 T4 T6 T5 T1 T7 T8 T6 T9 T7 C5 T10 T8 T11 C8 T12 T9 C7 L1 L2 T10 L3 L4 T11 C6 L5 T12 S1 L1 C8 C7 C8 S2 C7 S2, 3 L2 S3 S4 L3 S5 S1 S2 L4 L5 L1 L2 L3

L5 S1 S2

L4

S1 S1 L5 L5 L4 L4

Levels of principal dermatomes T10 Level of umbilicus C5 Clavicles T12 Inguinal or groin regions C5, 6, 7 Lateral parts of upper limbs L1, 2, 3, 4 Anterior and inner surfaces of lower limbs C8, T1 Medial sides of upper limbs L4, 5, S1 Foot C6 Thumb L4 Medial side of great toe C6, 7, 8 Hand S1, 2, L5 Posterior and outer surfaces of lower limbs C8 Ring and little fingers S1 Lateral margin of foot and little toe T4 Level of nipples S2, 3, 4 Perineum ©

FIGURE 2.31 DERMATOMES• Sensory information below the head is localized to specific areas dorsal root is called a dermatome. This figure shows the der- of the body, which reflect the distribution of peripheral sensory matome segments and lists key dermatome levels used by clini- fibers that convey sensations to the spinal cord through the dorsal cians. Variability and overlap occur, so all dermatome segments roots (sensory nerve cell bodies reside in the corresponding dorsal are only approximations. root ganglion). The area of skin subserved by afferent fibers of one

82 Visual System: Receptors NEUROPHYSIOLOGY

A. Eyeball B. Section Inner limiting through retina membrane Axons at surface Lens of retina passing Iris Cornea via optic nerve, Suspensory chiasm, and tract ligament Ciliary body to lateral geniculate body Ganglion cell Anterior Posterior chamber chamber Müller cell (supporting glial Ora containing cell) serrata aqueous humor Amacrine cell Bipolar cell Vitreous humor Horizontal cell Rod Retina Cone Choroid Pigment cells Sclera of choroid Fovea Optic nerve

Synaptic Synaptic ending ending fully depolarized polarized

Synaptic bar C. Rod in dark D. Rod in light

Photons Nucleus of light

Rhodopsin Lumirhodopsin Metabolic energy Metarhodopsin Centriole Current Retinene Retinene (basal body) flow + + Opsin Opsin Na+ Na+ Vitamin A permeability permeability Vitamin A decreased increased Circulation

©

FIGURE 2.32 VISUAL RECEPTORS• The rods and cones of the retina transduce light into electrical sig- dark the cell is depolarized, but it is hyperpolarized in the light. nals. As illustrated for the rod, light is absorbed by rhodopsin, and This electrical response to light is distinct from other receptor through the second messenger cGMP (not shown), Naϩ channels responses, in which the response to a stimulus results in a depolar- in the membrane close and the cell hyperpolarizes. Thus, in the ization of the receptor cell membrane.

83 NEUROPHYSIOLOGY Visual System: Visual Pathway

Central darker circle represents G macular G zone Overlapping visual fields Lightest A A shades represent B B monocular H H fields Each quadrant a different color Projection on Projection on RRC C left retina right retina

P P Optic Choroid Choroid (II) nerves Optic chiasm Periphery Macula Structure of retina (schematic): Projection on right A Amacrine cells Projection on left dorsal lateral B Bipolar cells dorsal lateral geniculate nucleus C Cones geniculate nucleus Optic tracts G Ganglion cells Lateral H Horizontal cells geniculate P Pigment cells bodies R Rods

Calcarine fissure

Projection Projection on left on right occipital lobe occipital lobe ©

FIGURE 2.33 RETINOGENICULOSTRIATE VISUAL PATHWAY• The retina has two types of photoreceptors: cones that mediate optic chiasm while information from the temporal retina remains in color vision and rods that mediate light perception but with low the ipsilateral optic tract. Fibers synapse in the lateral geniculate acuity. The greatest acuity is found in the region of the macula of nucleus (visual field is topographically represented here and the retina, where only cones are found (upper left panel). Visual inverted), and signals are conveyed to the visual cortex on the signals are conveyed by the ganglion cells whose axons course in medial surface of the occipital lobe. the optic nerves. Visual signals from the nasal retina cross in the

84 Auditory System: Cochlea NEUROPHYSIOLOGY

Cochlear nerve A. Membranous Utricle Semicircular labyrinth within canals bony labyrinth Saccule (path of sound waves)

Scala vestibuli Cochlear duct (scala media) Scala tympani Round window Oval window and stapes B. Section through turn Vestibular (Reissner’s) of cochlea Scala vestibuli membrane (perilymph); weakly Cochlear duct (scala media; endolymph) Efferent positive +80 mV nerve fibers Tectorial membrane Spiral ligament Bone Afferent Scala tympani Outer hair cells; Ϫ60 mV nerve fibers (perilymph); 0 mV Basilar membrane Spiral ganglion Inner hair cell; Ϫ60 mV

C. Spiral organ of Corti Hair cells Tectorial membrane Inner Outer

Stereocilia

Rods and tunnel of Corti

Basilar membrane Supporting cells Spiral lamina Afferent nerve fibers 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 response to pressure changes imparted on the oval window of the accomplished by the hair cells, which depolarize in response to cochlea in response to vibrations of the tympanic membrane. vibration of the basilar membrane. The basilar membrane moves in

85 NEUROPHYSIOLOGY Auditory System: Pathways

Acoustic area of temporal lobe cortex

Medial geniculate body

Brachium of inferior colliculus Inferior colliculus Midbrain Correspondence between cochlea and acoustic area of cortex: Lateral Low tones lemnisci Middle tones Nuclei of High tones Medulla lateral oblongata lemnisci

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

Dorsal acoustic stria Reticular formation Inner Outer Trapezoid body Spiral ganglion Hair cells Intermediate acoustic stria Superior olivary complex ©

FIGURE 2.35 AUDITORY PATHWAYS• The cochlea transduces sound into electrical signals. Axons convey geniculate bodies) and then the acoustic cortex in the transverse these signals to the dorsal and ventral cochlear nuclei, where it is gyrus of the temporal lobe, where information is tonotopically rep- tonotopically organized. Following a series of integrated relay resented (low, middle, and high tones). pathways, the ascending pathway projects to the thalamus (medial

86 Vestibular System: Receptors NEUROPHYSIOLOGY

A. Membranous labyrinth Superior semi- Vestibular ganglion circular canal Vestibular and cochlear Cristae within divisions of ampullae vestibulocochlear n. Horizontal semi- Maculae circular canal Saccule Posterior semi- Utricle circular canal Cochlear duct (scala media)

B. Section of crista

Opposite wall of ampulla Gelatinous cupula C. Section of macula Hair tufts Otoconia Hair cells Gelatinous otolithic Nerve fibers membrane Basement Hair tuft membrane Hair cells Supporting cells Basement membrane Nerve fibers

D. Structure and innervation Excitation of hair cells Inhibition Kinocilium Kinocilium Stereocilia Basal body Stereocilia Cuticle Cuticle Basal body

Hair cell (type I) Hair cell (type II)

Supporting cells Supporting cell

Afferent nerve Efferent nerve calyx endings

Efferent nerve Afferent nerve ending endings

Basement Myelin sheath membrane

Myelin sheath ©

FIGURE 2.36 VESTIBULAR RECEPTORS• The vestibular apparatus detects movement of the head in the form such as the pull of gravity. The three semicircular canals are of linear and angular acceleration. This information is important for aligned so that the angular movement of the head can be sensed in the control of eye movements so that the retina can be provided all planes. The sensory hair cells are located in the maculae of the with a stable visual image. It is also important for the control of utricle and saccule and in the cristae within each ampullae. posture. The utricle and saccule respond to linear acceleration,

87 NEUROPHYSIOLOGY Vestibular System: Vestibulospinal Tracts

Excitatory endings Superior Inhibitory Medial endings Vestibular nuclei Lateral Inferior Ascending fibers in medial Rostral longitudinal fasciculi Upper limb Trunk

Ventral Dorsal

To Lower cerebellum limb Caudal Somatotopical pattern in lateral vestibular nucleus Vestibular ganglion and nerve Motor neuron (controlling neck muscles)

Medial vestibulo- Fibers from cristae Lateral (rotational stimuli) spinal fibers in medial vestibulospinal longitudinal fasciculi tract Excitatory Excitatory endings interneuron to back Inhibitory muscles ? ? interneuron Fibers from maculae (gravitational stimuli)

Lower part of To flexor muscles cervical To extensor muscles spinal cord Inhibitory ending ? ? To axial To axial muscles muscles Inhibitory Excitatory ending ending Lumbar part of Lateral vestibulospinal tract spinal cord

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 sta- cord (muscle control), cerebellum (vermis), reticular formation bility of the head and to maintain balance and posture. Axons con- (vomiting center), extraocular muscles, and cortex (conscious per- vey vestibular information to the vestibular nuclei in the pons, and ception). This figure shows only the spinal cord pathways. then secondary axons distribute this information to five sites: spinal

88 Gustatory (Taste) System: Receptors NEUROPHYSIOLOGY

A. Tongue B. Section through Foliate vallate papillae papilla Taste buds

Duct of gustatory (Ebner’s) gland

C. Taste bud

Epithelium Fungiform Basement membrane papillae Vallate papillae Nerve plexus Microvilli Nerve fibers Taste pore emerging from taste buds Taste cells

Desmosomes Large nerve fiberBasement membrane Fibroblast Epithelium Granules Small nerve fiber Schwann cell Microvilli Intercellular space Large nerve fiber Collagen

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

FIGURE 2.38 TASTE RECEPTORS• Taste buds on the tongue respond to various chemical stimuli. Taste larize neurons connected to the taste cells. A single taste bud can cells, like neurons, normally have a net negative charge internally respond to more than one stimulus. The four traditional taste qualities and are depolarized by stimuli, thus releasing transmitters that depo- 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 Pontine taste area nucleus and Trigeminal (V) n. Motor nucleus of trigeminal n. Maxillary n. Mandibular n.

Pons Pterygo- palatine Greater petrosal n. ganglion

Geniculate ganglion

Facial (VII) n. Otic and ganglion Lingual n. Nervus inermedius

Rostral part of nucleus Chorda of solitary tract tympani Glossopharyngeal (IX) n. Fungiform papillae

Lower Foliate papillae part of Valiate papillae medulla oblongata

Petrosal (inferior) ganglion of Epiglottis glossopharyngeal n. Larynx Nodose (inferior) ganglion of vagus n. Vagus (X) n. Superior laryngeal n. ©

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

90 Olfactory System: Receptors NEUROPHYSIOLOGY

Olfactory A. Distribution Cribriform plate bulb of olfactory of ethmoid bone epithelium (blue area)

Lateral nasal wall Septum

B. Schema of section through olfactory mucosa Cribriform plate

Schwann cell

Olfactory gland

Unmyelinated olfactory axons Basement membrane Sustentacular cells Endoplasmic reticulum Nucleus

Olfactory cells

Dendrites

Terminal bars (desmosomes) Olfactory rod (vesicle)

Villi

Cilia

Mucus

©

FIGURE 2.40 OLFACTORY RECEPTORS• The sensory cells that make up the olfactory epithelium respond to qualities that can be sensed: floral, ethereal (e.g., pears), musky, odorants by depolarizing. Like taste buds, an olfactory cell can camphor (e.g., eucalyptus), putrid, and pungent (e.g., vinegar, pep- respond to more than one odorant. There are six general odor permint).

91 NEUROPHYSIOLOGY Olfactory System: Pathway

Efferent fibers

Afferent fibers

Granule cell (excited by Fibers from contralateral olfactory bulb and inhibiting to mitral and tufted cells) Fibers to contralateral olfactory bulb Mitral cell Anterior commissure Recurrent process Tufted cell Medial olfactory stria Periglom- Olfactory trigone and erular cell olfactory tubercle Glomerulus Anterior perforated Olfactory substance nerve fibers Lateral olfactory stria

Lateral olfactory tract nucleus

Piriform lobe

Uncus

Amygdala (in phantom)

Entorhinal area

Olfactory epithelium Olfactory tract

Olfactory nerves Anterior olfactory nucleus

Olfactory bulb Cribriform plate of ethmoid bone ©

FIGURE 2.41 OLFACTORY PATHWAY• Olfactory stimuli are detected by the nerve fibers of the olfactory sure (some efferent projections course to the contralateral olfactory epithelium and conveyed to the olfactory bulb (detailed local cir- bulb, blue lines) or terminate in the ipsilateral olfactory trigone cuitry shown in upper left panel). Integrated signals pass along the (olfactory tubercle). Axons then project to the primary olfactory olfactory tract and centrally diverge to pass to the anterior commis- cortex (piriform cortex), entorhinal cortex, and amygdala.

92 Installing Adobe Acrobat Reader 5.0

The images and text included in this atlas are contained in a Portable Document Format (pdf) file and can be viewed with Adobe Acrobat Reader. A copy of Acrobat Reader 5.0 is included on this CD. You will need to install or upgrade to Acrobat Reader 5.0 in order to have full functionality.

Please follow these instructions: 1. Choose Run from the Start menu and then click Browse. 2. Double-click the InstallAcrobat.exe file to open the Reader Installer. 3. Follow the onscreen instructions.

Running the Atlas of Neuroanatomy and Neurophysiology

Windows 1. Insert the CD into the CD-ROM drive. 2. If Acrobat Reader 5.0 is not already installed on your computer, follow the installation instructions above. 3. Choose Run from the Start menu and type x:\ (where x is the letter of your CD- ROM drive). 4. Under Files of Type, click All Files. 5. Double-click the Neuro Atlas.pdf file to open the program. 6. For best viewing results, use the Edit menu to access the Preferences. Select General and open the Display preferences to activate the Smooth Line Art option.

Macintosh 1. Insert the CD into the CD-ROM drive. 2. If Acrobat Reader 5.0 is not already installed on your computer, follow the installation instructions above. 3. Double-click the Neuro Atlas.pdf file to open the program. 4. For best viewing results, use the Edit menu to access the Preferences. Select General and open the Display preferences to activate the Smooth Line Art option.

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