Medical knowledge | Anatomy » Frank H. Netter - Atlas of Neuroanatomy and Neurophysiology

Atlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations Illustrations by Frank H. Netter, MD John A. Craig, MD James Perkins, MS, MFA Text by John T. Hansen, PhD Bruce M. Koeppen, MD, PhD Atlas of Neuroanatomy and 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 Netterartcom 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.SA Foreword Frank Netter: The Physician, The Artist, The Art This selection of the art of Dr. Frank H Netter on neuroanatomy and neurophysiology is drawn from the Atlas of Human Anatomy and Netter’s Atlas of Human Physiology. Viewing these pictures again prompts reflection on Dr. Netter’s work and his roles as physician and artist Frank H. Netter was born in 1906 in New York City He pursued his artistic muse at the Sorbonne, the Art Student’s League, and the National Academy of Design before entering medical school at New York University, where he received his M.D degree in 1931 During his student years, Dr Netter’s notebook sketches attracted the attention of the medical faculty and other physicians, allowing him to augment his income by illustrating articles and textbooks. He continued illustrating as a sideline after establishing a surgical practice in 1933, but ultimately opted to give up his practice in favor of

a full-time commitment to art. After service in the United States Army during the Second World War, Dr. Netter began his long collaboration with the CIBA Pharmaceutical Company (now Novartis Pharmaceuticals). This 45-year partnership resulted in the production of the extraordinary collection of medical art so familiar to physicians and other medical professionals worldwide. When Dr. Netter’s work is discussed, attention is focused primarily on Netter the artist and only secondarily on Netter the physician. As a student of Dr Netter’s work for more than forty years, I can say that the true strength of a Netter illustration was always established well before brush was laid to paper. In that respect each plate is more of an intellectual than an artistic or aesthetic exercise It is easy to appreciate the aesthetic qualities of Dr. Netter’s work, but to overlook its intellectual qualities is to miss the real strength and intent of the art This intellectual process requires thorough

understanding of the topic, as Dr Netter wrote: “Strange as it may seem, the hardest part of making a medical picture is not the drawing at all It is the planning, the conception, the determination of point of view and the approach which will best clarify the subject which takes the most effort.” Years before the inception of “the integrated curriculum,” Netter the physician realized that a good medical illustration can include clinical information and physiologic functions as well as anatomy. In pursuit of this principle Dr Netter often integrates pertinent basic and clinical science elements in his anatomic interpretations Although he was chided for this heresy by a prominent European anatomy professor, many generations of students training to be physicians rather than anatomists have appreciated Dr. Netter’s concept The integration of physiology and clinical medicine with anatomy has led Dr. Netter to another, more subtle, choice in his art. Many texts and atlases

published during the period of Dr Netter’s career depict anatomy clearly based on cadaver specimens with renderings of shrunken and shriveled tissues and organs. Netter the physician chose to render “live” versions of these structuresnot shriveled, colorless, formaldehyde-soaked tissues, but plump, robust organs, glowing with color! The value of Dr. Netter’s approach is clearly demonstrated by the plates in this selection John A. Craig, MD Austin, Texas This volume brings together two distinct but related aspects of the work of Frank H. Netter, MD, and associated artists Netter is best known as the creator of the Atlas of Human Anatomy, a comprehensive textbook of gross anatomy that has become the standard atlas for students of the subject. But Netter’s work included far more than anatomical art. In the pages of Clinical Symposia, a series of monographs published over a period of more than 50 years, and in The Netter Collection of Medical Illustrations, this premier

medical artist created superb illustrations of biological and physiological processes, disease pathology, clinical presentations, and medical procedures. As a service to the medical community, Novartis Pharmaceuticals has commissioned this special edition of Netter’s work, which includes his beautiful and instructive illustrations of nervous system anatomy as well as his depictions of neurophysiological concepts and functions. We hope that readers will find Dr Netter’s renderings of neurological form and function interesting and useful. Click any title below to link to that plate. Part 1 Neuroanatomy CerebrumMedial Views . 2 CerebrumInferior View. 3 Basal Nuclei (Ganglia). 4 Thalamus . 5 Cerebellum . 6 Brainstem . 7 Fourth Ventricle and Cerebellum . 8 Accessory Nerve (XI) . 9 Arteries to Brain and Meninges .

10 Arteries to Brain: Schema . 11 Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves: Schema. 27 Trigeminal Nerve (V): Schema . 28 Facial Nerve (VII): Schema . 29 Vestibulocochlear Nerve (VIII): Schema. 30 Glossopharyngeal Nerve (IX): Schema . 31 Vagus Nerve (X): Schema . 32 Accessory Nerve (XI): Schema . 33 Hypoglossal Nerve (XII): Schema . 34 Nerves of Heart . 35 Arteries of Brain: Inferior Views . 12 Autonomic Nerves and Ganglia of Abdomen. 36 Cerebral Arterial Circle (Willis) . 13 Nerves of Stomach and Duodenum . 37 Arteries of Brain: Frontal View and Section . 14 Nerves of Stomach and Duodenum (continued) . 38 Arteries of Brain: Lateral and Medial Views . 15 Nerves of Small Intestine . 39 Arteries of Posterior Cranial Fossa . 16 Nerves of Large Intestine .

40 Veins of Posterior Cranial Fossa . 17 Deep Veins of Brain. 18 Nerves of Kidneys, Ureters and Urinary Bladder . 41 Subependymal Veins of Brain . 19 Nerves of Pelvic Viscera: Male . 42 Hypothalamus and Hypophysis . 20 Nerves of Pelvic Viscera: Female . 43 Arteries and Veins of Hypothalamus and Hypophysis . 21 Median Nerve . 44 Relation of Spinal Nerve Roots to Vertebrae . 22 Radial Nerve in Arm and Nerves of Posterior Shoulder . 46 Autonomic Nervous System: General Topography. 23 Spinal Nerve Origin: Cross Sections. 24 Olfactory Nerve (I): Schema . 25 Optic Nerve (II) (Visual Pathway): Schema . 26 Ulnar Nerve . 45 Radial Nerve in Forearm . 47 Sciatic Nerve and Posterior Cutaneous Nerve of Thigh . 48 Tibial Nerve .

49 Common Fibular (Peroneal) Nerve. 50 NEUROANATOMY Sagittal section of brain in situ Cingulate gyrus Cingulate sulcus Medial frontal gyrus Sulcus of corpus callosum Fornix Septum pellucidum Interventricular foramen (Monro) Interthalamic adhesion Thalamus and 3rd ventricle Subcallosal (parolfactory) area Anterior commissure Subcallosal gyrus Hypothalamic sulcus Lamina terminalis Supraoptic recess Optic chiasm Tuber cinereum Hypophysis (pituitary gland) Mammillary body Cerebral peduncle Pons Medial surface of cerebral hemisphere: brainstem excised Cingulate gyrus Mammillothalamic fasciculus Mammillary body Cerebrum: Medial Views Paracentral sulcus Central sulcus (Rolando) Paracentral lobule Marginal sulcus Corpus callosum Precuneus Superior sagittal sinus Choroid plexus of 3rd ventricle Stria medullaris of thalamus Parietooccipital sulcus Cuneus Habenular commissure Pineal body Posterior commissure Calcarine sulcus Straight sinus in tentorium cerebelli Cerebral

aqueduct (Sylvius) Great cerebral vein (Galen) Superior colliculus Inferior colliculus Tectal (quadrigeminal) plate Cerebellum Superior medullary velum 4th ventricle and choroid plexus Inferior medullary velum Medulla oblongata Genu Rostrum Trunk Splenium of corpus callosum Isthmus of cingulate gyrus Parietooccipital sulcus Cuneus Uncus Calcarine sulcus Optic nerve (II) Lingual gyrus Olfactory tract Crus Body Column Collateral sulcus Rhinal sulcus Medial occipitotemporal gyrus Occipitotemporal sulcus Lateral occipitotemporal gyrus 2 of fornix Fimbria of hippocampus Dentate gyrus Parahippocampal gyrus NEUROANATOMY Cerebrum: Inferior View Sectioned brainstem Frontal pole of cerebrum Straight gyrus Olfactory sulcus Orbital sulci Longitudinal cerebral fissure Genu of corpus callosum Lamina terminalis Olfactory bulb Olfactory tract Orbital gyri Optic chiasm Temporal pole Optic nerve (II) (cut) Lateral sulcus (Sylvius) Hypophysis (pituitary gland) Inferior temporal

sulcus Inferior temporal gyrus Anterior perforated substance Optic tract Tuber cinereum Mammillary body Inferior (inferolateral) margin of cerebrum Posterior perforated substance (in interpeduncular fossa) Rhinal sulcus Cerebral crus Uncus Lateral geniculate body Inferior temporal gyrus Substantia nigra Medial geniculate body Occipitotemporal sulcus Red nucleus Lateral occipitotemporal gyrus Pulvinar of thalamus Superior colliculus (of corpora quadrigemina) Collateral sulcus Cerebral aqueduct Parahippocampal gyrus Splenium of corpus callosum Medial occipitotemporal gyrus Calcarine sulcus Apex of cuneus Occipital pole of cerebrum Longitudinal cerebral fissure Isthmus of cingulate gyrus 3 NEUROANATOMY Horizontal sections through cerebrum Basal Nuclei (Ganglia) A B Genu of corpus callosum Head of caudate nucleus Lateral ventricle Anterior limb of internal capsule Genu Septum pellucidum Posterior limb Column of fornix Putamen Globus pallidus Insula (island

of Reil) Lentiform nucleus 3rd ventricle Interthalamic adhesion External capsule Thalamus Claustrum Crus of fornix Retrolenticular part of internal capsule Choroid plexus of lateral ventricle Tail of caudate nucleus Hippocampus and fimbria Splenium of corpus callosum Occipital (posterior) horn of lateral ventricle Habenula Organization of basal nuclei (ganglia) A B Caudate Putamen Globus nucleus pallidus Striatum Lentiform nucleus Corpus striatum Basal nuclei (ganglia) Pineal body Cleft for internal capsule Caudate nucleus Levels of sections above Body Head A B Thalamus A B Pulvinar Lentiform nucleus (globus pallidus medial to putamen) Amygdaloid body Medial geniculate body Lateral geniculate body Tail of caudate nucleus Interrelationship of thalamus, lentiform nucleus, caudate nucleus and amygdaloid body (schema): left lateral view 4 NEUROANATOMY Thalamus Corpus callosum (cut) Interventricular foramen (Monro) Head of caudate nucleus Tela choroidea

(cut edge) of 3rd ventricle Septum pellucidum 3rd ventricle Columns of fornix Choroid plexus Anterior tubercle Superior thalamostriate vein Stria terminalis Pes hippocampi Interthalamic adhesion Temporal (inferior) horn of lateral ventricle Lamina affixa Internal cerebral vein Stria medullaris Dentate gyrus Habenular trigone Collateral eminence Pulvinar (retracted) Hippocampus Lateral geniculate body Fimbria of hippocampus Medial geniculate body Posterior commissure Brachium of superior colliculus Habenular commissure Brachium of inferior colliculus Pineal body Collateral trigone Superior colliculus Calcar avis Inferior colliculus Occipital (posterior) horn of lateral ventricle Cerebellum Calcarine sulcus 3rd ventricle Internal medullary lamina Interthalamic adhesion a Pulvinar rio r MD LP M Intralaminar nuclei Inte LP 3rd ventricle VPL M External medullary lamina VP Median nuclei Schematic section through thalamus (at level of broken

line shown in figure at right) Thalamic nuclei CM LD LP M MD VA VI VL VP VPL VPM Centromedian Lateral dorsal Lateral posterior Medial Medial dorsal Ventral anterior Ventral intermedial Ventral lateral Ventral posterior Ventral posterolateral Ventral posteromedial VL VP Reticular nucleus VP CM rn L VA La m in n te An dia Me ial d na Me llar y lami u d D e L al m VP M VI Pulvinar Lateral geniculate body Medial geniculate body Schematic representation of thalamus (external medullary lamina and reticular nuclei removed) Lateral nuclei Medial nuclei Anterior nuclei 5 NEUROANATOMY Cerebellum Superior surface Anterior cerebellar notch Anterior lobe Quadrangular lobule (H IV-V) Central lobule (II & III) Primary fissure Horizontal fissure Culmen (IV & V) Simple lobule (H VI) Superior vermis Posterior lobe Declive (VI) Postlunate fissure Folium (VII A) Superior semilunar (anseriform) lobule (H VII A) Horizontal fissure Inferior semilunar (caudal)

lobule (H VII B) Posterior cerebellar notch Central lobule Superior vermis Anterior lobe Inferior surface Wing of central lobule Lingula (I) Superior Middle Inferior Superior medullary velum Flocculus (H X) Flocculonodular lobe 4th ventricle Posterolateral (dorsolateral) fissure Inferior medullary velum Retrotonsillar fissure Nodule (X) Inferior vermis Cerebellar peduncles Posterior lobe Uvula (IX) Pyramid (VIII) Tuber (VII B) Posterior cerebellar notch Decussation of superior cerebellar peduncles Tonsil Biventer lobule (H VIII) Secondary (postpyramidal) fissure Horizontal fissure Inferior semilunar (caudal) lobule (H VII B) Cerebral crus Medial longitudinal fasciculus 4th ventricle Nuclear layer of medulla oblongata Superior medullary velum Fastigial Cerebellar nuclei Superior cerebellar peduncle Globose Lingula (I) Dentate Vermis Emboliform Section in plane of superior cerebellar peduncle 6 NEUROANATOMY Brainstem Thalamus (cut surface) Posterolateral

view Lateral geniculate body Optic tract Pulvinars of thalami Pineal body Medial geniculate body Superior colliculi Brachia of superior and inferior colliculi Inferior colliculi Cerebral crus Trochlear nerve (IV) Pons Superior medullary velum Trigeminal nerve (V) Superior cerebellar peduncle Middle cerebellar peduncle Rhomboid fossa of 4th ventricle Vestibulocochlear nerve (VIII) Facial nerve (VII) Glossopharyngeal (IX) and vagus (X) nerves Inferior cerebellar peduncle Cuneate tubercle Hypoglossal nerve (XII) Gracile tubercle Accessory nerve (XI) Dorsal roots of 1st spinal nerve (C1) Cuneate fasciculus Gracile fasciculus Olfactory tract Anterior view Anterior perforated substance Infundibulum (pituitary stalk) Optic chiasm Mammillary bodies Optic tract Temporal lobe (cut surface) Oculomotor nerve (III) Tuber cinereum Trochlear nerve (IV) Cerebral crus Trigeminal nerve (V) Abducent nerve (VI) Lateral geniculate body Facial nerve (VII) and intermediate

nerve Posterior perforated substance Vestibulocochlear nerve (VIII) Pons Flocculus of cerebellum Middle cerebellar peduncle Olive Choroid plexus of 4th ventricle Glossopharyngeal nerve (IX) Pyramid Ventral roots of 1st spinal nerve (C1) Decussation of pyramids Vagus nerve (X) Hypoglossal nerve (XII) Accessory nerve (XI) 7 NEUROANATOMY Fourth Ventricle and Cerebellum Habenular trigone Posterior view Medial Lateral 3rd ventricle Geniculate bodies Dorsal median sulcus Pulvinar of thalamus Superior cerebellar peduncle Pineal body Locus ceruleus Superior colliculus Medial eminence Inferior colliculus Facial colliculus Trochlear nerve (IV) Vestibular area Superior medullary velum Dentate nucleus of cerebellum Superior Middle Inferior Cerebellar peduncles Striae medullares Lateral recess Tenia of 4th ventricle Superior fovea Cuneate tubercle Sulcus limitans Gracile tubercle Inferior fovea Dorsal median sulcus Trigeminal tubercle Lateral funiculus

Hypoglossal trigone Vagal trigone Cuneate fasciculus Gracile fasciculus Obex Interthalamic adhesion Median sagittal section Posterior commissure Body of fornix Habenular commissure Thalamus (in 3rd ventricle) Pineal body Interventricular foramen (Monro) Splenium of corpus callosum Great cerebral vein (Galen) Anterior commissure Lamina terminalis Lingula (I) Central lobule (II-III) Culmen (IV-V) Declive (VI) Folium (VII A) Hypothalamic sulcus Cerebral peduncle Cerebral aqueduct (Sylvius) Superior colliculus Tectal (quadrigeminal) plate Superior medullary velum Inferior colliculus Pons Inferior medullary velum Medial longitudinal fasciculus Tuber (VII B) 4th ventricle Pyramid (VIII) Choroid plexus of 4th ventricle Uvula (IX) Nodulus (X) Medulla oblongata Median aperture (foramen of Magendie) Decussation of pyramids Central canal of spinal cord 8 Vermis of cerebellum Choroid plexus of 4th ventricle Tonsil of cerebellum Vermis of cerebellum NEUROANATOMY

Accessory Nerve (XI): Schema Nucleus ambiguus Vagus nerve (X) Cranial root of accessory nerve (joins vagus nerve and via recurrent laryngeal nerve supplies muscles of larynx, except cricothyroid)* Spinal root of accessory nerve Foramen magnum Jugular foramen Superior ganglion of vagus nerve Accessory nerve (XI)* Inferior ganglion of vagus nerve C1 spinal nerve C2 spinal nerve Accessory nerve (to sternocleidomastoid and trapezius muscles) Sternocleidomastoid muscle (cut) C3 spinal nerve C4 spinal nerve Trapezius muscle Efferent fibers Proprioceptive fibers *Recent evidence suggests that the accessory nerve lacks a cranial root and has no connection to the vagus nerve. Verification of this finding awaits further investigation. 9 NEUROANATOMY Left middle meningeal artery Posterior cerebral artery Superior cerebellar artery Basilar artery Arteries to Brain and Meninges Middle cerebral artery Anterior cerebral artery Anterior communicating artery Ophthalmic artery Left

labyrinthine (internal acoustic) artery Posterior communicating artery Mastoid branch of left occipital artery Cavernous sinus Anterior inferior cerebellar artery Middle meningeal artery Posterior meningeal branch of left ascending pharyngeal artery Posterior inferior cerebellar artery Left and right vertebral arteries (intracranial part) Maxillary artery Superficial temporal artery Posterior meningeal branch of vertebral artery External carotid artery Anterior meningeal branch of vertebral artery Posterior auricular artery Facial artery Occipital artery Internal carotid artery Carotid sinus Carotid body Vertebral artery (cervical part) Transverse process of C6 Deep cervical artery Supreme intercostal artery Costocervical trunk Subclavian artery 10 Lingual artery Ascending pharyngeal artery Superior laryngeal artery Superior thyroid artery Common carotid artery Ascending cervical artery (cut) Inferior thyroid artery Thyrocervical trunk Brachiocephalic trunk Internal

thoracic artery NEUROANATOMY Arteries to Brain: Schema Anterior communicating artery Anterior cerebral artery 1 Ophthalmic artery Middle cerebral artery Supraorbital artery Posterior communicating artery Supratrochlear artery Caroticotympanic branch of internal carotid artery 3 3 2 3 Lacrimal artery 1 Dorsal nasal artery Posterior cerebral artery Middle meningeal artery 3 Superior cerebellar artery Angular artery Anterior tympanic artery Superficial temporal artery 1 1 Middle meningeal artery Posterior auricular artery 4 Facial artery Maxillary artery Basilar artery 5 4 5 Occipital artery Lingual artery Anterior inferior cerebellar artery 5 Posterior inferior cerebellar artery 5 Ascending pharyngeal artery Anterior spinal artery 5 External carotid artery Spinal segmental medullary branches 5 Vertebral artery 5 Internal carotid artery Common carotid artery Superior thyroid artery Deep cervical artery 5 Common carotid artery Transverse

cervical artery Suprascapular artery Vertebral artery Supreme intercostal artery Ascending cervical artery Costocervical trunk Inferior thyroid artery Thyrocervical trunk Subclavian artery Subclavian artery Internal thoracic artery Brachiocephalic trunk Arch Aorta Descending Ascending Anastomoses 1 2 3 4 5 Right–Left Carotid–Vertebral Internal carotid–External carotid Subclavian–Carotid Subclavian–Vertebral 11 NEUROANATOMY Arteries of Brain: Inferior Views Medial frontobasal (orbitofrontal) artery Anterior communicating artery Anterior cerebral artery Distal medial striate artery (recurrent artery of Heubner) Internal carotid artery Anterolateral central (lenticulostriate) arteries Middle cerebral artery Lateral frontobasal (orbitofrontal) artery Prefrontal artery Anterior choroidal artery Posterior communicating artery Posterior cerebral artery Superior cerebellar artery Basilar artery Pontine arteries Labyrinthine (internal acoustic) artery Anterior

inferior cerebellar artery Vertebral artery Anterior spinal artery Posterior inferior cerebellar artery (PICA) (cut) Posterior spinal artery Distal medial striate artery (recurrent artery of Heubner) Anterior communicating artery Anterior cerebral artery Middle cerebral artery Posterior communicating artery Anterior choroidal artery Optic tract Posterior cerebral artery Cerebral crus Lateral geniculate body Posterior medial choroidal artery Posterior lateral choroidal artery Choroid plexus of lateral ventricle Medial geniculate body Pulvinar of thalamus Lateral ventricle 12 Cerebral arterial circle (Willis) (broken line) NEUROANATOMY Cerebral Arterial Circle (Willis) Vessels dissected out: inferior view Anterior cerebral artery (A2 segment) Distal medial striate artery (recurrent artery of Heubner) Anteromedial central (perforating) arteries Anterior communicating artery Anterior cerebral artery (A1 segment) Hypothalamic artery Anterolateral central (lenticulostriate)

arteries Ophthalmic artery Internal carotid artery Middle cerebral artery Superior hypophyseal artery Posterior communicating artery Inferior hypophyseal artery Anterior choroidal artery Posterior cerebral artery (P2 segment) (P1 segment) Superior cerebellar artery Basilar artery Pontine arteries Anterior inferior cerebellar artery Thalamotuberal (premammillary) artery Posteromedial central (perforating) arteries Thalamoperforating artery Posteromedial central (paramedian) arteries Labyrinthine (internal acoustic) artery Vertebral artery Vessels in situ: inferior view Anterior cerebral artery Hypothalamic artery Anterior communicating artery Optic chiasm Cavernous sinus Internal carotid artery Superior hypophyseal artery Middle cerebral artery Inferior hypophyseal artery Posterior communicating artery Infundibulum (pituitary stalk) and long hypophyseal portal veins Adenohypophysis (anterior lobe of pituitary gland) Neurohypophysis (posterior lobe of pituitary gland)

Posteromedial central (perforating) arteries Efferent hypophyseal veins Superior cerebellar artery Posterior cerebral artery Basilar artery 13 NEUROANATOMY Corpus callosum Arteries of Brain: Frontal View and Section Paracentral artery Medial frontal branches Anterolateral central (lenticulostriate) arteries Pericallosal artery Lateral frontobasal (orbitofrontal) artery Callosomarginal artery Polar frontal artery Prefrontal artery Anterior cerebral arteries Precentral (pre-rolandic) and central (rolandic) sulcal arteries Medial frontobasal (orbitofrontal) artery Anterior parietal (postcentral sulcal) artery Distal medial striate artery (recurrent artery of Heubner) Posterior parietal artery Internal carotid artery Branch to angular gyrus Anterior choroidal artery Temporal branches (anterior, middle and posterior) Posterior cerebral artery Superior cerebellar artery Middle cerebral artery and branches (deep in lateral cerebral [sylvian] sulcus) Basilar and

pontine arteries Labyrinthine (internal acoustic) artery Anterior communicating artery Posterior communicating artery Anterior inferior cerebellar artery Vertebral artery Posterior inferior cerebellar artery Anterior spinal artery Posterior spinal artery Falx cerebri Corpus striatum (caudate and lentiform nuclei) Anterolateral central (lenticulostriate) arteries Insula (island of Reil) Limen of insula Precentral (pre-rolandic), central (rolandic) sulcal and parietal arteries Lateral cerebral (sylvian) sulcus Temporal branches of middle cerebral artery Temporal lobe Middle cerebral artery Internal carotid artery 14 Callosomarginal arteries and Pericallosal arteries (branches of anterior cerebral arteries) Trunk of corpus callosum Internal capsule Septum pellucidum Rostrum of corpus callosum Anterior cerebral arteries Distal medial striate artery (recurrent artery of Heubner) Anterior communicating artery Optic chiasm NEUROANATOMY Arteries of Brain: Lateral and Medial Views

Anterior parietal (postcentral sulcal) artery Posterior parietal artery Central (rolandic) sulcal artery Branch to angular gyrus Precentral (pre-rolandic) sulcal artery Terminal branches of posterior cerebral artery Prefrontal sulcal artery Terminal branches of anterior cerebral artery Lateral frontobasal (orbitofrontal) artery Left middle cerebral artery Left anterior cerebral artery Occipitotemporal branches Anterior communicating artery Posterior temporal branch Right anterior cerebral artery Middle temporal branch Left internal carotid artery Polar temporal artery Medial frontal branches Posterior Intermediate Anterior Pericallosal artery Superior and inferior terminal branches (trunks) Anterior temporal branch Paracentral artery Cingular branches Right posterior cerebral artery Precuneal artery Callosomarginal artery Polar frontal artery Dorsal branch to corpus callosum Parietooccipital branch Calcarine branch Right anterior cerebral artery Medial frontobasal

(orbitofrontal) artery Anterior communicating artery (cut) Medial occipital artery Distal medial striate artery (recurrent artery of Heubner) Posterior temporal branch Anterior temporal branch Right internal carotid artery Posterior communicating artery Note: Anterior parietal (postcentral sulcal) artery also occurs as separate anterior parietal and postcentral sulcal arteries 15 NEUROANATOMY Arteries of Posterior Cranial Fossa Thalamogeniculate arteries Lateral and medial geniculate bodies of left thalamus Choroid plexuses of lateral ventricles Anterior choroidal artery Pulvinars of left and right thalami Crura of fornix Splenium of corpus callosum Anterolateral central (lenticulostriate) arteries Occipital (posterior) horn of right lateral ventricle Right dorsal branch to corpus callosum (posterior pericallosal artery) Heads of caudate nuclei Septum pellucidum Parietooccipital Corpus callosum Calcarine Branches of right posterior cerebral artery Anterior

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

16 Left posterior spinal artery Left vertebral artery NEUROANATOMY Veins of Posterior Cranial Fossa Left superior and inferior colliculi Left pulvinar Basal vein (Rosenthal) Right pulvinar Internal cerebral veins Posterior mesencephalic vein Splenium of corpus callosum Medial geniculate body Great cerebral vein (Galen) Lateral mesencephalic vein Dorsal vein of corpus callosum Lateral geniculate body Inferior sagittal sinus Left thalamus (cut surface) Straight sinus Falx cerebri Optic tract Confluence of sinuses Tentorium cerebelli (cut) Inferior thalamostriate veins Left transverse sinus (cut) Deep middle cerebral vein (cut) Superior sagittal sinus Anterior cerebral vein Optic nerve (II) C C CL D F TU L N Superior vermian vein P U Anterior pontomesencephalic vein Inferior vermian vein Falx cerebelli (cut) and occipital sinus T Inferior cerebellar hemispheric veins Trigeminal nerve (V) Transverse pontine vein Intraculminate vein Superior

cerebellar vein (inconstant) Petrosal vein (draining to superior petrosal sinus) Preculminate vein Lateral pontine vein Precentral cerebellar vein Superior retrotonsillar vein Anteromedian medullary vein Vein of lateral recess of 4th ventricle Superior, middle and inferior cerebellar peduncles Anterior spinal vein (Inferior retrotonsillar) vein of cerebellomedullary cistern Posterior spinal vein 4th ventricle Parts of cerebellum L CL C D F Lingula Central lobule Culmen Declive Folium TU Tuber P Pyramid U Uvula N Nodule T Tonsil 17 NEUROANATOMY Deep Veins of Brain Longitudinal cerebral fissure Anterior cerebral veins Rostrum of corpus callosum Septum pellucidum Anterior vein of septum pellucidum Head of caudate nucleus Anterior vein of caudate nucleus Transverse veins of caudate nucleus Interventricular foramen (Monro) Columns of fornix Superior thalamostriate vein Superior choroid vein and choroid plexus of lateral ventricle Thalamus Tela choroidea of 3rd ventricle

Lateral direct vein Posterior vein of caudate nucleus Internal cerebral veins Basal vein (Rosenthal) Great cerebral vein (Galen) Inferior sagittal sinus Straight sinus Tentorium cerebelli Transverse sinus Confluence of sinuses Superior sagittal sinus Dissection: superior view Uncal vein Anterior cerebral vein Superficial middle cerebral vein (draining to sphenoparietal sinus) Optic chiasm Deep middle cerebral vein Cerebral crus Basal vein (Rosenthal) Lateral geniculate body Medial geniculate body Inferior cerebral veins Pulvinar of thalamus Splenium of corpus callosum Great cerebral vein (Galen) Dissection: inferior view 18 Inferior anastomotic vein (Labbé) NEUROANATOMY Subependymal Veins of Brain Posterior veins of septum pellucidum Superior thalamic veins Superior choroid vein Lateral direct vein Posterior terminal vein of caudate nucleus (posterior part of thalamostriate vein) Internal cerebral veins (right and left) Transverse veins of caudate nucleus Medial

(atrial) vein of lateral ventricle Superior thalamostriate vein Lateral (atrial) vein of lateral ventricle Lateral ventricle Splenium of corpus callosum Anterior vein of caudate nucleus Great cerebral vein (Galen) Anterior vein of septum pellucidum Dorsal vein of corpus callosum Genu of corpus callosum Inferior sagittal sinus Internal occipital vein Straight sinus Occipital (posterior) horn of lateral ventricle Interventricular foramen (Monro) Anterior commissure Interthalamic adhesion Anterior cerebral vein Optic chiasm Cerebellum 3rd ventricle Deep middle cerebral vein Inferior thalamostriate veins Basal vein (Rosenthal) Temporal (inferior) horn of lateral ventricle Posterior mesencephalic vein Superior vermian vein Hippocampal and inferior ventricular veins Cerebral aqueduct 4th ventricle Lateral and median apertures of 4th ventricle Veins on lateral wall of ventricle Veins on medial wall and floor of ventricle All other veins 19 NEUROANATOMY Hypothalamus and

Hypophysis Septum pellucidum Thalamus Fornix Hypothalamic sulcus Anterior commissure Paraventricular Posterior Dorsomedial Principal nuclei of hypothalamus Supraoptic Ventromedial Arcuate (infundibular) Mammillary Mammillothalamic tract Optic chiasm Infundibulum (pituitary stalk) Dorsal longitudinal fasciculus and other descending pathways Hypophysis (pituitary gland) Lamina terminalis Hypothalamic sulcus Paraventricular hypothalamic nucleus Supraoptic hypothalamic nucleus Supraopticohypophyseal tract Tuberohypophyseal tract Mammillary body Hypothalamohypophyseal tract Infundibulum (pituitary stalk) Arcuate (infundibular) nucleus Pars tuberalis Adenohypophysis (anterior lobe of pituitary gland) Fibrous trabecula Median eminence of tuber cinereum Infundibular stem Pars intermedia Pars distalis Infundibular process Cleft 20 Neurohypophysis (posterior lobe of pituitary gland) Arteries and Veins of Hypothalamus and Hypophysis NEUROANATOMY Hypothalamic vessels

Primary plexus of hypophyseal portal system Superior hypophyseal artery Long hypophyseal portal veins Artery of trabecula Short hypophyseal portal veins Trabecula (fibrous tissue) Efferent hypophyseal vein to cavernous sinus Secondary plexus of hypophyseal portal system Adenohypophysis (anterior lobe of pituitary gland) Efferent hypophyseal vein to cavernous sinus Neurohypophysis (posterior lobe of pituitary gland) Capillary plexus of infundibular process Efferent hypophyseal vein to cavernous sinus Efferent hypophyseal veins to cavernous sinus Inferior hypophyseal artery 21 NEUROANATOMY Relation of Spinal Nerve Roots to Vertebrae C1 C2 C2 C3 C3 C4 C4 C5 C5 C6 C6 C7 C7 C8 T1 T1 T2 T2 T3 T3 T4 T4 T5 T5 T6 T6 T7 T7 T8 T8 T9 T9 T10 T10 T11 T11 T12 T12 L1 Base of skull Cervical enlargement Lumbar enlargement L4 C1 spinal nerve exits above C1 vertebra C1 L4 L5 C8 spinal nerve exits below C7 vertebra (there are 8 cervical nerves but only 7 cervical vertebrae) L5 S1

S2 Lumbar disc protrusion does not usually affect nerve exiting above disc. Lateral protrusion at disc level L4–5 affects L5 spinal nerve, not L4 spinal nerve. Protrusion at disc level L5–S1 affects S1 spinal nerve, not L5 spinal nerve L4 Conus medullaris (termination of spinal cord) L1 L4 L2 L2 L5 L3 L3 Internal terminal filum (pial part) L5 Cauda equina L4 L4 S1 L5 L5 Sacrum External terminal filum (dural part) S2 S1 S3 Termination of dural sac S4 S5 Coccygeal nerve Coccyx Cervical nerves Thoracic nerves Lumbar nerves Sacral and coccygeal nerves 22 S2 S3 S4 S5 Coccygeal nerve Medial protrusion at disc level L4–5 rarely affects L4 spinal nerve but may affect L5 spinal nerve and sometimes S1–4 spinal nerves Autonomic Nervous System: General Topography Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) Vagus nerve (X) Internal carotid nerve and plexus Superior cervical sympathetic ganglion C4 spinal nerve Middle cervical sympathetic

ganglion Vertebral ganglion Cervicothoracic (stellate) ganglion Sympathetic trunk Cervical (sympathetic) cardiac nerves Superior Middle Inferior Thoracic (sympathetic) cardiac nerves 6th intercostal nerve (ventral ramus of T6 spinal nerve) Sympathetic trunk 6th thoracic sympathetic ganglion Gray and white rami communicantes Greater splanchnic nerve Lesser splanchnic nerve Least splanchnic nerve Aorticorenal ganglion Lumbar splanchnic nerves (sympathetic) Gray rami communicantes Sacral splanchnic nerves (sympathetic) Pelvic splanchnic nerves (sacral parasympathetic outflow) Sciatic nerve Inferior hypogastric (pelvic) plexus NEUROANATOMY Ciliary ganglion Pterygopalatine ganglion Otic ganglion Chorda tympani nerve Lingual nerve Submandibular ganglion Pharyngeal and superior laryngeal branches of vagus nerve Recurrent laryngeal branch of vagus nerve Superior cervical Inferior cervical Thoracic Cardiac branches of vagus nerve Cardiac plexus Anterior Posterior Pulmonary plexuses

Esophageal plexus Thoracic aortic plexus Anterior vagal trunk Posterior vagal trunk Celiac ganglion Celiac trunk and plexus Superior mesenteric ganglion Superior mesenteric artery and plexus Intermesenteric (abdominal aortic) plexus Inferior mesenteric ganglion Inferior mesenteric artery and plexus Superior hypogastric plexus Parasympathetic branch from inferior hypogastric plexus to descending colon Hypogastric nerves Rectal plexus Vesical plexus Sympathetic fibers Parasympathetic fibers Prostatic plexus 23 NEUROANATOMY Spinal Nerve Origin: Cross Sections Section through thoracic vertebra Aorta Body of vertebra Fat in epidural space Dura mater Sympathetic ganglion Arachnoid mater* Ventral root Subarachnoid space White and gray rami communicantes Pia mater* Recurrent meningeal branches of spinal nerve Spinal nerve Ventral ramus (intercostal nerve) Dorsal ramus Pleura Lung Spinal sensory (dorsal root) ganglion Dorsal root Lateral horn of gray matter of spinal cord

Section through lumbar vertebra Lateral branch Sympathetic ganglion Medial branch Dura mater Arachnoid mater Gray ramus communicans Internal vertebral (epidural) venous plexus Ventral root Fat in epidural space Spinal nerve Ventral ramus (contributes to lumbar plexus) Dorsal ramus Dorsal and ventral roots of lumbar and sacral spinal nerves forming cauda equina Spinal sensory (dorsal root) ganglion Dorsal root Conus medullaris *Leptomeninges 24 of dorsal ramus of spinal nerve NEUROANATOMY Olfactory Nerve (I): Schema Subcallosal (parolfactory) area Septal area and nuclei Olfactory bulb cells: schema Fibers from Fibers to Efferent fibers to olfactory bulb Afferent fibers from bulb to central connections and contralateral bulb Contralateral olfactory bulb Anterior commissure Medial olfactory stria Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process Tufted cell Periglomerular cell Glomerulus Olfactory nerve fibers Olfactory

cells Olfactory mucosa Olfactory tract Olfactory trigone and olfactory tubercle Olfactory nerves (I) Lateral olfactory stria Uncus Olfactory bulb Lateral olfactory tract nucleus Cribriform plate of ethmoid bone Anterior perforated substance Anterior olfactory nucleus Amygdaloid body (phantom) Piriform lobe Hippocampal fimbria Dentate gyrus Parahippocampal gyrus 25 NEUROANATOMY Optic Nerve (II) (Visual Pathway): Schema G Central darker circle represents macular zone G A B A Overlapping visual fields Lighter shades represent monocular fields B Each quadrant a different color H H R RC P Projection on right retina Projection on left retina C P Choroid Choroid Periphery Macula Optic nerves (II) Optic chiasm Structure of retina: schema A B C G H P R Amacrine cells Bipolar cells Cones Ganglion cells Horizontal cells Pigment cells Rods Projection on left dorsal lateral geniculate nucleus Optic tracts Projection on right dorsal lateral geniculate nucleus

Lateral geniculate bodies Optic radiation Optic radiation Calcarine sulcus Calcarine sulcus Projection on left occipital lobe 26 Projection on right occipital lobe NEUROANATOMY Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves: Schema Long ciliary nerve Short ciliary nerves Anterior ethmoidal nerve Superior oblique muscle Levator palpebrae superioris muscle Superior rectus muscle Ciliary ganglion Posterior ethmoidal nerve Abducent nucleus Sensory root of ciliary ganglion Trochlear nucleus Sympathetic root of ciliary ganglion Oculomotor nucleus Superior division of oculomotor nerve Accessory oculomotor (Edinger-Westphal) nucleus (parasympathetic) Frontal nerve (cut) Lacrimal nerve (cut) Nasociliary nerve Trochlear nerve (IV) Oculomotor nerve (III) Ophthalmic nerve (V1) Abducent nerve (VI) Infraorbital nerve Zygomatic nerve (cut) Inferior oblique muscle Ciliary muscle Pterygopalatine ganglion Inferior division of oculomotor nerve Dilator muscle of pupil

Sphincter muscle of pupil Medial rectus muscle Inferior rectus muscle Efferent fibers Afferent fibers Sympathetic fibers Parasympathetic fibers Parasympathetic root of ciliary ganglion Mandibular nerve (V3) Internal carotid artery and nerve plexus Maxillary nerve (V2) Lateral rectus muscle and abducent nerve (turned back) Cavernous plexus Common tendinous ring 27 NEUROANATOMY Efferent fibers Afferent fibers Proprioceptive fibers Parasympathetic fibers Sympathetic fibers Trigeminal Nerve (V): Schema Ophthalmic nerve (V1) Tentorial (meningeal) branch Nasociliary nerve Lacrimal nerve Sensory root of ciliary ganglion Frontal nerve Ciliary ganglion Posterior ethmoidal nerve Long ciliary nerve Short ciliary nerves Anterior ethmoidal nerve Supraorbital nerve Supratrochlear nerve Infratrochlear nerve Internal nasal branches and External nasal branches of anterior ethmoidal nerve Trigeminal nerve (V) ganglion and nuclei Motor nucleus Mesencephalic nucleus Principal sensory nucleus

Spinal tract and nucleus Maxillary nerve (V2) Meningeal branch Zygomaticotemporal nerve Zygomaticofacial nerve Zygomatic nerve Infraorbital nerve Pterygopalatine ganglion Superior alveolar branches of infraorbital nerve Nasal branches (posterior superior lateral, nasopalatine and posterior superior medial) Facial nerve (VII) Chorda tympani nerve Nerve (vidian) of pterygoid canal (from facial nerve [VII] and carotid plexus) Pharyngeal branch Greater and lesser palatine nerves Deep temporal nerves (to temporalis muscle) Lateral pterygoid and masseteric nerves Tensor veli palatini and medial pterygoid nerves Buccal nerve Mental nerve Inferior dental plexus Lingual nerve 28 Superficial temporal branches Articular branch and anterior auricular nerves Auriculotemporal nerve Submandibular ganglion Mylohyoid nerve Inferior alveolar nerve Otic ganglion Mandibular nerve (V3) Tensor tympani nerve Parotid branches Meningeal branch Lesser petrosal nerve (from glossopharyngeal nerve [IX])

NEUROANATOMY Facial Nerve (VII): Schema Facial nerve (VII) Greater petrosal nerve Internal acoustic meatus Geniculate ganglion Deep petrosal nerve (from internal carotid plexus) Intermediate nerve Motor nucleus of facial nerve Internal carotid plexus (on internal carotid artery) Lesser petrosal nerve Nerve (vidian) of pterygoid canal Superior salivatory nucleus Solitary tract nucleus Otic ganglion Pterygopalatine ganglion Facial muscles Frontal belly (frontalis) of occipitofrontalis Orbicularis oculi Corrugator supercilii Zygomaticus major Zygomaticus minor che Temporal bran Procerus Levator labii superioris Levator labii superioris alaeque nasi s Levator anguli oris Nasalis Depressor septi nasi Orbicularis oris Zygomatic bra nch es anterior 2⁄3 Taste: tongue of Buccal branches Occipital branch of posterior auricular nerve al br anc h Depressor anguli oris Cer vic Depressor labii inferioris Mentalis (Risorius) (not shown) al Margin ular ib d man branch

Buccinator Occipital belly (occipitalis) of occipitofrontalis muscle Branches to auricular muscles Posterior auricular nerve Nerve to stapedius muscle Stylomastoid foramen Tympanic plexus Platysma Tympanic nerve (Jacobson) (from glossopharyngeal nerve) Sublingual gland Efferent fibers Afferent fibers Parasympathetic fibers Sympathetic fibers Submandibular gland Submandibular ganglion Lingual nerve (from trigeminal nerve) Chorda tympani nerve Glossopharyngeal nerve (IX) Digastric muscle (posterior belly) Stylohyoid muscle Caroticotympanic nerve (from internal carotid plexus) 29 NEUROANATOMY Vestibulocochlear Nerve (VIII): Schema Afferent fibers Facial canal Tympanic cavity Geniculum of facial nerve (site of geniculate ganglion) Chorda tympani nerve Greater petrosal nerve Head of malleus Cochlear (spiral) ganglion Incus Vestibular nerve Cochlear nerve Motor root of facial nerve and intermediate nerve Vestibulocochlear nerve (VIII) Medulla oblongata (cross section)

Ampulla of lateral semicircular duct Internal acoustic meatus Medial Vestibular nuclei (diagrammatic) Ampulla of superior semicircular duct Superior Anterior Inferior Posterior Utricle Cochlear nuclei Ampulla of posterior semicircular duct Lateral Inferior cerebellar peduncle (to cerebellum) Vestibular ganglion Saccule Superior division Inferior division 30 of vestibular nerve NEUROANATOMY Glossopharyngeal Nerve (IX): Schema Spinal tract and spinal nucleus of trigeminal nerve Efferent fibers Afferent fibers Parasympathetic fibers Solitary tract nucleus Tympanic nerve (Jacobson) Tympanic cavity and plexus Stylomastoid foramen Caroticotympanic nerve (from internal carotid plexus) Nucleus ambiguus Inferior salivatory nucleus Geniculate ganglion of facial nerve Greater petrosal nerve Deep petrosal nerve Nerve (vidian) of pterygoid canal Lesser petrosal nerve Pterygopalatine ganglion Mandibular nerve (V3) Otic ganglion Auriculotemporal nerve Parotid gland Tubal branch

of tympanic plexus Pharyngotympanic (auditory) tube and pharyngeal opening Glossopharyngeal nerve (IX) Stylopharyngeus muscle (and branch from glossopharyngeal nerve) Jugular foramen Communication to auricular branch of vagus nerve Superior and Inferior ganglia of Glossopharyngeal nerve Communication to facial nerve (VII) Taste and somatic sensation: posterior 1 ⁄3 of tongue Vagus nerve (X) Superior cervical sympathetic ganglion Sympathetic trunk Carotid branch of glossopharyngeal nerve Internal carotid artery Pharyngeal plexus Carotid sinus Pharyngeal, tonsillar and lingual branches of glossopharyngeal nerve Carotid body Common carotid artery Pharyngeal branch of vagus nerve External carotid artery 31 NEUROANATOMY SEE ALSO PLATE 160 Vagus Nerve (X): Schema Posterior nucleus of vagus nerve (parasympathetic and visceral afferent) Glossopharyngeal nerve (IX) Solitary tract nucleus (visceral afferents including taste) Meningeal branch of vagus nerve Auricular branch of

vagus nerve Spinal tract and spinal nucleus of trigeminal nerve (somatic afferent) Pharyngotympanic (auditory) tube Levator veli palatini muscle Nucleus ambiguus (motor to pharyngeal and laryngeal muscles) Salpingopharyngeus muscle Cranial root of accessory nerve* (see next plate) Palatoglossus muscle Vagus nerve (X) Palatopharyngeus muscle Jugular foramen Superior pharyngeal constrictor muscle Superior ganglion of vagus nerve Inferior ganglion of vagus nerve Stylopharyngeus muscle Middle pharyngeal constrictor muscle Pharyngeal branch of vagus nerve (motor to muscles of palate and lower pharynx; sensory to lower pharynx) Inferior pharyngeal constrictor muscle Cricothyroid muscle Trachea Esophagus Right subclavian artery Right recurrent laryngeal nerve Heart Hepatic branch of anterior vagal trunk (in lesser omentum) Celiac branches from anterior and posterior vagal trunks to celiac plexus Celiac and superior mesenteric ganglia and celiac plexus Hepatic plexus Gallbladder

and bile ducts Liver Pyloric branch from hepatic plexus Pancreas Duodenum Ascending colon Cecum Appendix 32 Communicating branch of vagus nerve to carotid branch of glossopharyngeal nerve Pharyngeal plexus Superior laryngeal nerve: Internal branch (sensory and parasympathetic) External branch (motor to cricothyroid muscle) Superior cervical cardiac branch of vagus nerve Inferior cervical cardiac branch of vagus nerve Thoracic cardiac branch of vagus nerve Left recurrent laryngeal nerve (motor to muscles of larynx except cricothyroid; sensory and parasympathetic to larynx below vocal folds; parasympathetic, efferent and afferent to upper esophagus and trachea) Pulmonary plexus Cardiac plexus Esophageal plexus Anterior vagal trunk Gastric branches of anterior vagal trunk (branches from posterior trunk behind stomach) Vagal branches (parasympathetic motor, secretomotor and afferent fibers) accompany superior mesenteric artery and its branches usually as far as left colic (splenic)

flexure Small intestine Efferent fibers Afferent fibers Parasympathetic fibers NEUROANATOMY Accessory Nerve (XI): Schema SEE ALSO PLATE 28 Nucleus ambiguus Vagus nerve (X) Cranial root of accessory nerve (joins vagus nerve and via recurrent laryngeal nerve supplies muscles of larynx, except cricothyroid)* Spinal root of accessory nerve Foramen magnum Jugular foramen Superior ganglion of vagus nerve Accessory nerve (XI)* Inferior ganglion of vagus nerve C1 spinal nerve C2 spinal nerve Accessory nerve (to sternocleidomastoid and trapezius muscles) Sternocleidomastoid muscle (cut) C3 spinal nerve C4 spinal nerve Trapezius muscle Efferent fibers Proprioceptive fibers *Recent evidence suggests that the accessory nerve lacks a cranial root and has no connection to the vagus nerve. Verification of this finding awaits further investigation. 33 NEUROANATOMY Hypoglossal Nerve (XII): Schema Hypoglossal nerve (XII) (in hypoglossal canal) Hypoglossal nucleus Superior

longitudinal Intrinsic muscles of tongue Transverse and vertical Inferior longitudinal Meningeal branch Styloglossus muscle Occipital condyle Inferior ganglion of vagus nerve Ventral rami of C1, 2, 3 form ansa cervicalis of cervical plexus Superior cervical sympathetic ganglion Superior root of ansa cervicalis Genioglossus muscle Internal carotid artery Geniohyoid muscle Hyoglossus muscle Thyrohyoid muscle Omohyoid muscle (superior belly) Sternohyoid muscle Inferior root of ansa cervicalis Ansa cervicalis Internal jugular vein Common carotid artery Sternothyroid muscle Omohyoid muscle (inferior belly) Efferent fibers Afferent fibers 34 NEUROANATOMY Nerves of Heart Superior cervical sympathetic ganglion Vagus nerve (X) (Conjoined sympathetic and vagal) superior cervical cardiac nerves Middle cervical sympathetic ganglion Middle cervical (sympathetic) cardiac nerve Phrenic nerve Inferior cervical (vagal) cardiac nerve Vertebral ganglion Inferior thyroid artery Vertebral

artery Cervicothoracic (stellate) ganglion Ansa subclavia Superior cervical sympathetic ganglion Vagus nerve (X) Superior cervical (sympathetic) cardiac nerve Superior cervical (vagal) cardiac nerve Middle cervical sympathetic ganglion Phrenic nerve Middle cervical (sympathetic) cardiac nerve Inferior cervical (vagal) cardiac nerve Vertebral ganglion Cervicothoracic (stellate) ganglion Inferior cervical sympathetic cardiac nerves Recurrent laryngeal nerve Inferior cervical (sympathetic) cardiac nerves Thoracic cardiac branch of vagus nerve 4th thoracic sympathetic ganglion Thoracic (sympathetic) cardiac branches Cardiac plexus 3rd thoracic sympathetic ganglion Thoracic (sympathetic) cardiac branches Thoracic cardiac branch of vagus nerve Recurrent laryngeal nerve Phrenic nerve (cut) 35 NEUROANATOMY Right sympathetic trunk Thoracic duct Autonomic Nerves and Ganglia of Abdomen Anterior, Posterior vagal trunks Right greater and lesser splanchnic nerves Left gastric artery

and plexus Right phrenic nerve Left greater splanchnic nerve Inferior phrenic arteries and plexuses Left lesser splanchnic nerve Right greater and lesser splanchnic nerves Splenic artery and plexus Right suprarenal plexus Right aorticorenal ganglion Celiac ganglia Common hepatic artery and plexus Superior mesenteric ganglion and plexus Left aorticorenal ganglion Right least splanchnic nerve Left sympathetic trunk Right renal artery and plexus Intermesenteric (aortic) plexus Right sympathetic trunk Inferior mesenteric ganglion White and gray rami communicantes Left colic artery and plexus Cisterna chyli Inferior mesenteric artery and plexus Gray ramus communicans 3rd lumbar ganglion of sympathetic trunk 2nd and 3rd lumbar splanchnic nerves Right ureter and plexus Right testicular (ovarian) artery and plexus 4th lumbar splanchnic nerve 1st sacral ganglion of sympathetic trunk Gray rami communicantes Left common iliac artery and plexus Superior rectal artery and

plexus Superior hypogastric plexus Internal and external iliac arteries and plexuses Right and left hypogastric nerves to inferior hypogastric (pelvic) plexus Left sacral plexus Pelvic splanchnic nerves 36 NEUROANATOMY Nerves of Stomach and Duodenum Right and left inferior phrenic arteries and plexuses Anterior and posterior layers of lesser omentum Branch from hepatic plexus to cardia via lesser omentum Right greater splanchnic nerve Hepatic branch of anterior vagal trunk Anterior vagal trunk Celiac branch of posterior vagal trunk Celiac branch of anterior vagal trunk Left gastric artery and plexus Vagal branch from hepatic plexus to pyloric part of stomach Hepatic plexus Right gastric artery and plexus Anterior gastric branch of anterior vagal trunk Left greater splanchnic nerve Left lesser splanchnic nerve Splenic artery and plexus Celiac ganglia and plexus Plexus on gastro-omental (gastroepiploic) arteries Superior mesenteric artery and plexus Plexus on inferior

pancreaticoduodenal artery Plexus on first jejunal artery Plexus on anterior superior and anterior inferior pancreaticoduodenal arteries (posterior pancreaticoduodenal arteries and plexuses not visible in this view) 37 NEUROANATOMY Nerves of Stomach and Duodenum (continued) Posterior gastric branch of posterior vagal trunk Plexus on gastro-omental (gastroepiploic) arteries Hepatic branch of anterior vagal trunk via lesser omentum Hepatic plexus Branch from hepatic plexus to cardia via lesser omentum Right gastric artery and plexus Right inferior phrenic artery and plexus Posterior vagal trunk Celiac branch of posterior vagal trunk Celiac branch of anterior vagal trunk Left gastric artery and plexus Left inferior phrenic artery and plexus Celiac ganglia and plexus Greater, lesser and least splanchnic nerves Aorticorenal ganglia Splenic artery and plexus Right phrenic nerve Phrenic ganglion Greater, Lesser, Least splanchnic nerves Branch from right inferior phrenic plexus

to cardia of stomach Right and left inferior phrenic arteries and plexuses Anterior vagal trunk Posterior vagal trunk View with stomach reflected cephalad Plexus on anterior superior and anterior inferior pancreaticoduodenal arteries Right greater, lesser and least splanchnic nerves Plexus on gastroduodenal artery Plexus on posterior superior and posterior inferior pancreaticoduodenal arteries Celiac ganglia Superior mesenteric ganglion and plexus Right aorticorenal ganglion Superior mesenteric ganglion and plexus 38 Celiac branches of anterior and posterior vagal trunks Left gastric artery and plexus Left greater, lesser and least splanchnic nerves Left aorticorenal ganglion Nerves of Small Intestine NEUROANATOMY Recurrent branch of left inferior phrenic artery and plexus to esophagus Anterior vagal trunk Posterior vagal trunk Hepatic branch of anterior vagal trunk (courses in lesser omentum, removed here) Celiac branches of anterior and posterior vagal trunks Inferior

phrenic arteries and plexuses Left gastric artery and plexus Hepatic plexus Greater splanchnic nerves Right gastric artery and plexus (cut) Celiac ganglia and plexus Gastroduodenal artery and plexus Lesser splanchnic nerves Least splanchnic nerves Aorticorenal ganglia Superior mesenteric ganglion Intermesenteric (aortic) plexus Inferior pancreaticoduodenal arteries and plexuses Superior mesenteric artery and plexus Middle colic artery and plexus (cut) Right colic artery and plexus Ileocolic artery and plexus Superior mesenteric artery and plexus Peritoneum (cut edge) Mesenteric branches Mesoappendix (contains appendicular artery and nerve plexus) 39 NEUROANATOMY Nerves of Large Intestine Anterior vagal trunk and hepatic branch Posterior vagal trunk Celiac branches of anterior and posterior vagal trunks Right inferior phrenic artery and plexus Right greater splanchnic nerve Marginal artery and plexus Esophagus Left inferior phrenic artery and plexus Left gastric artery and

plexus Left greater splanchnic nerve Celiac ganglia and plexus Left suprarenal plexus Right lesser and least splanchnic nerves Left lesser and least splanchnic nerves Right aorticorenal ganglion Left aorticorenal ganglion Superior mesenteric ganglion Left renal artery and plexus Middle colic artery and plexus 1st left lumbar splanchnic nerve Inferior pancreaticoduodenal arteries and plexuses Left lumbar sympathetic trunk Right colic artery and plexus Left colic artery and plexus Intermesenteric (aortic) plexus Inferior mesenteric ganglion, artery and plexus Ileocolic artery and plexus Sigmoid arteries and plexuses Cecal and appendicular arteries and plexuses Superior hypogastric plexus Right internal iliac artery and plexus (cut) Superior rectal artery and plexus Sacral sympathetic trunk Right sacral plexus Right and left hypogastric nerves Pelvic splanchnic nerves Middle rectal artery and plexus Right inferior hypogastric (pelvic) plexus Vesical plexus Rectal

plexus Urinary bladder 40 Rectosigmoid artery and plexus Nerves from inferior hypogastric (pelvic) plexuses to sigmoid colon, descending colon and left colic (splenic) flexure Nerves of Kidneys, Ureters and Urinary Bladder NEUROANATOMY Anterior vagal trunk Posterior vagal trunk Greater splanchnic nerve Celiac ganglia and plexus Lesser splanchnic nerve Superior mesenteric ganglion Least splanchnic nerve Aorticorenal ganglion Renal plexus and ganglion 2nd lumbar splanchnic nerve Renal and upper ureteric branches from intermesenteric plexus Intermesenteric (aortic) plexus Testicular (ovarian) artery and plexus Inferior mesenteric ganglion Sympathetic trunk and ganglion Middle ureteric branch Superior hypogastric plexus Sacral splanchnic nerves (branches from upper sacral sympathetic ganglia to hypogastric plexus) Gray ramus communicans Hypogastric nerves Sacral plexus Pudendal nerve Pelvic splanchnic nerves Inferior hypogastric (pelvic) plexus with periureteric loops and branches

to lower ureter Rectal plexus Vesical plexus Prostatic plexus 41 NEUROANATOMY Anterior vagal trunk Nerves of Pelvic Viscera: Male T10 spinal nerve (anterior ramus) Posterior vagal trunk and Celiac branch White and gray rami communicantes Greater Lesser Least Inferior phrenic arteries and plexuses Left gastric artery and gastric plexus Diaphragm Celiac ganglia, plexus and trunk Left renal artery and plexus Left aorticorenal ganglion L1 spinal nerve (anterior ramus) Superior mesenteric ganglion Superior mesenteric artery and plexus Gray White Intermesenteric (aortic) plexus Inferior mesenteric ganglion, artery and plexus Splanchnic nerves Rami communicantes 1st, 2nd, 3rd lumbar splanchnic nerves Gray rami communicantes Ureter and ureteric plexus Sympathetic trunk and ganglia Superior hypogastric plexus Superior rectal artery and plexus Hypogastric nerves 5th lumbar splanchnic nerve L5 spinal nerve (anterior ramus) Lumbosacral trunk Nerve from inferior hypogastric

plexus to sigmoid and descending colon (parasympathetic) Gray rami communicantes S1 spinal nerve (anterior ramus) Sacral splanchnic nerves (sympathetic) Pelvic splanchnic nerves (parasympathetic) Inferior hypogastric (pelvic) plexus Sacral plexus Obturator nerve and artery Piriformis muscle Ductus deferens and plexus Gluteus maximus muscle and sacro tuberous ligament Vesical plexus Rectal plexus (Ischio-)coccygeus muscle and sacrospinous ligament Prostatic plexus Cavernous nerves of penis Pudendal nerve Levator ani muscle Inferior anal (rectal) nerve Perineal nerve Dorsal nerve of penis Posterior scrotal nerves 42 NEUROANATOMY Nerves of Pelvic Viscera: Female Peritoneum Abdominal aorta Sympathetic trunk and L2 ganglion Inferior vena cava Extraperitoneal (subserous) fascia White and gray rami communicantes Common iliac vessels and plexus Lumbar splanchnic nerves Ureter Intermesenteric (aortic) plexus Ovarian artery and plexus Gray rami communicantes Superior

hypogastric plexus L5 spinal nerve Sacral promontory Superior hypogastric plexus Right hypogastric nerve (cut) Common iliac artery and plexus Right and left sacral sympathetic trunks and ganglia Ureter Internal iliac artery and plexus S1 Piriformis muscle S2 Sigmoid colon External iliac artery and plexus Right and left hypogastric nerves Uterus Right sympathetic trunk S3 Sacral splanchnic nerves (sympathetic) S4 S5 Pudendal nerve Left hypogastric nerve Inferior hypogastric (pelvic) plexus Uterine (fallopian) tube Ovary Pelvic splanchnic nerves (parasympathetic) Symphyseal surface of pubis Urinary bladder Vesical plexus (Ischio-)coccygeus muscle Rectal plexus Uterovaginal plexus Uterus (retracted) Rectum (retracted) 43 NEUROANATOMY Median Nerve Anterior view Note: Only muscles innervated by median nerve shown Musculocutaneous nerve Median nerve (C5, 6, 7, 8, T1) Medial Posterior Lateral Inconstant contribution Cords of brachial plexus Pronator teres

muscle (humeral head) Medial cutaneous nerve of arm Articular branch Medial cutaneous nerve of forearm Flexor carpi radialis muscle Axillary nerve Palmaris longus muscle Radial nerve Pronator teres muscle (ulnar head) Ulnar nerve Flexor digitorum superficialis muscle (turned up) Flexor digitorum profundus muscle (lateral part supplied by median [anterior interosseous] nerve; medial part supplied by ulnar nerve) Anterior interosseous nerve Flexor pollicis longus muscle Pronator quadratus muscle Cutaneous innervation Palmar branch of median nerve Thenar muscles Abductor pollicis brevis Opponens pollicis Superficial head of flexor pollicis brevis (deep head supplied by ulnar nerve) 1st and 2nd lumbrical muscles Palmar view Communicating branch of median nerve with ulnar nerve Common palmar digital nerves Proper palmar digital nerves Dorsal branches to dorsum of middle and distal phalanges Posterior (dorsal) view 44 NEUROANATOMY Ulnar Nerve Anterior view Note: Only

muscles innervated by ulnar nerve shown Ulnar nerve (C7, 8, T1) (no branches above elbow) Inconstant contribution Medial epicondyle Articular branch (behind condyle) Cutaneous innervation Flexor digitorum profundus muscle (medial part only; lateral part supplied by anterior interosseous branch of median nerve) Palmar view Flexor carpi ulnaris muscle (drawn aside) Dorsal branch of ulnar nerve Posterior (dorsal) view Flexor pollicis brevis muscle (deep head only; superficial head and other thenar muscles supplied by median nerve) Adductor pollicis muscle Palmar branch Superficial branch Deep branch Palmaris brevis Abductor digiti minimi Flexor digiti minimi brevis Opponens digiti minimi Hypothenar muscles Common palmar digital nerve Communicating branch of median nerve with ulnar nerve Palmar and dorsal interosseous muscles 3rd and 4th lumbrical muscles (turned down) Proper palmar digital nerves (dorsal digital nerves are from dorsal branch) Dorsal branches to dorsum of

middle and distal phalanges 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 also by branches from C3 and C4) Deltoid muscle Teres minor muscle Axillary nerve (C5, 6) Superior lateral cutaneous nerve of arm Rhomboid minor muscle Radial nerve (C5, 6, 7, 8, T1) Inconstant contribution Rhomboid major muscle Inferior lateral cutaneous nerve of arm Posterior cutaneous nerve of forearm Infraspinatus muscle Teres major muscle Lower subscapular nerve (C5, 6) Posterior cutaneous nerve of arm (branch of radial nerve in axilla) Long head Triceps brachii muscle Lateral intermuscular septum Brachialis muscle (lateral part; remainder of muscle supplied by musculocutaneous nerve) Lateral head Medial head Brachioradialis muscle Triceps brachii tendon Medial epicondyle Extensor carpi radialis longus muscle Olecranon Anconeus muscle Extensor

digitorum muscle Extensor carpi ulnaris muscle 46 Extensor carpi radialis brevis muscle NEUROANATOMY Radial Nerve in Forearm Inconstant contribution Radial nerve (C5, 6, 7, 8, T1) Superficial (terminal) branch Deep (terminal) branch Posterior view Lateral epicondyle Anconeus muscle Brachioradialis muscle Extensor carpi radialis longus muscle Supinator muscle Extensor carpi radialis brevis muscle Extensor carpi ulnaris muscle Extensor- supinator group of muscles Extensor digitorum muscle and extensor digiti minimi muscle Extensor indicis muscle Extensor pollicis longus muscle Abductor pollicis longus muscle Extensor pollicis brevis muscle Posterior interosseous nerve (continuation of deep branch of radial nerve distal to supinator muscle) Superficial branch of radial nerve From axillary nerve Superior lateral cutaneous nerve of arm Inferior lateral cutaneous nerve of arm Posterior cutaneous nerve of arm From radial nerve Posterior cutaneous nerve of forearm Superficial

branch of radial nerve and dorsal digital branches Dorsal digital nerves Cutaneous innervation from radial and axillary nerves 47 NEUROANATOMY Sciatic Nerve and Posterior Cutaneous Nerve of Thigh Posterior cutaneous nerve of thigh (S1, 2, 3) Greater sciatic foramen Inferior cluneal nerves Sciatic nerve (L4, 5, S1, 2, 3) Perineal branches Common fibular (peroneal) division of sciatic nerve Tibial division of sciatic nerve Long head (cut) of biceps femoris muscle Short head of biceps femoris muscle Adductor magnus muscle (also partially supplied by obturator nerve) Cutaneous innervation Long head (cut) of biceps femoris muscle Semitendinosus muscle Semimembranosus muscle Tibial nerve Common fibular (peroneal) nerve Articular branch Posterior cutaneous nerve of thigh Articular branch Plantaris muscle Medial sural cutaneous nerve Lateral sural cutaneous nerve Sural communicating branch Gastrocnemius muscle Common fibular (peroneal) nerve via lateral sural cutaneous

nerve Sural nerve Medial sural cutaneous nerve Soleus muscle From sciatic nerve Tibial nerve Medial calcaneal branches Medial and lateral plantar nerves 48 Superficial fibular (peroneal) nerve Sural nerve Lateral calcaneal branches Lateral dorsal cutaneous nerve Tibial nerve via medial calcaneal branches NEUROANATOMY Tibial Nerve Common fibular (peroneal) nerve Tibial nerve (L4, 5, S1, 2, 3) Articular branch Lateral sural cutaneous nerve (cut) Medial sural cutaneous nerve (cut) Medial calcaneal branches (S1, 2) Articular branches Medial plantar nerve (L4, 5) From tibial nerve Plantaris muscle Lateral plantar nerve (S1, 2) Gastrocnemius muscle (cut) Saphenous nerve (L3, 4) Sural nerve (S1, 2) via lateral calcaneal and lateral dorsal cutaneous branches Nerve to popliteus muscle Popliteus muscle Cutaneous innervation of sole Interosseous nerve of leg Soleus muscle (cut and partly retracted) Flexor digitorum longus muscle Tibialis posterior muscle Flexor

hallucis longus muscle Sural nerve (cut) Lateral calcaneal branch Medial calcaneal branch Flexor retinaculum (cut) Flexor retinaculum (cut) Tibial nerve Medial calcaneal branch Medial plantar nerve Flexor digitorum brevis muscle and nerve Abductor hallucis muscle and nerve Flexor hallucis brevis muscle and nerve 1st lumbrical muscle and nerve Common plantar digital nerves Proper plantar digital nerves Lateral calcaneal branch of sural nerve Lateral plantar nerve Nerve to abductor digiti minimi muscle Quadratus plantae muscle and nerve Abductor digiti minimi muscle Deep branch to interosseous muscles, 2nd, 3rd and 4th lumbrical muscles and Adductor hallucis muscle Superficial branch to 4th interosseous muscle and Flexor digiti minimi brevis muscle Common and Proper plantar digital nerves Lateral dorsal cutaneous nerve Note: Articular branches not shown 49 NEUROANATOMY Common fibular (peroneal) nerve (phantom) Common Fibular (Peroneal) Nerve Lateral sural cutaneous nerve

(phantom) Articular branches Biceps femoris tendon Recurrent articular nerve Common fibular (peroneal) nerve (L4, 5, S1, 2) Extensor digitorum longus muscle (cut) Head of fibula Deep fibular (peroneal) nerve Fibularis (peroneus) longus muscle (cut) Tibialis anterior muscle Cutaneous innervation Superficial fibular (peroneal) nerve Branches of lateral sural cutaneous nerve Fibularis (peroneus) longus muscle Extensor digitorum longus muscle Extensor hallucis longus muscle Fibularis (peroneus) brevis muscle Lateral sural cutaneous nerve Medial dorsal cutaneous nerve Intermediate dorsal cutaneous nerve Inferior extensor retinaculum (partially cut) Lateral dorsal cutaneous nerve (branch of sural nerve) Dorsal digital nerves 50 Superficial fibular (peroneal) nerve Lateral branch of deep fibular (peroneal) nerve to Extensor hallucis brevis and Extensor digitorum brevis muscles Medial branch of deep fibular (peroneal) nerve Deep fibular (peroneal) nerve Sural nerve via

lateral dorsal cutaneous branch Click any title below to link to that plate. Part 2 Neurophysiology Organization of the Brain: Cerebrum. 52 The Cerebral Cortex . 70 Organization of the Brain: Cell Types. 53 Descending Motor Pathways . 71 Blood-Brain Barrier . 54 Cerebellum: Afferent Pathways. 72 Synaptic Transmission: Morphology of Synapses . 55 Cerebellum: Efferent Pathways . 73 Synaptic Transmission: Neuromuscular Junction . 56 Synaptic Transmission: Visceral Efferent Endings . 57 Cutaneous Sensory Receptors . 74 Cutaneous Receptors: Pacinian Corpuscle. 75 Proprioception and Reflex Pathways: I . 76 Synaptic Transmission: Inhibitory Mechanisms . 58 Proprioception and Reflex Pathways: II . 77 Synaptic Transmission: Chemical Synaptic Transmission . 59 Proprioception and Reflex

Pathways: IV. 79 Synaptic Transmission: Temporal and Spatial Summation . 60 Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition . 61 Cerebrospinal Fluid (CSF): Circulation of CSF . 62 Spinal Cord: Ventral Rami. 63 Spinal Cord: Membranes and Nerve Roots . 64 Peripheral Nervous System . 65 Autonomic Nervous System: Schema . 66 Autonomic Nervous System: Cholinergic and Adrenergic Synapses . 67 Proprioception and Reflex Pathways: III . 78 Sensory Pathways: I . 80 Sensory Pathways: II . 81 Sensory Pathways: III. 82 Visual System: Receptors. 83 Visual System: Visual Pathway . 84 Auditory System: Cochlea . 85 Auditory System: Pathways . 86 Vestibular System: Receptors . 87 Vestibular System: Vestibulospinal Tracts. 88 Gustatory (Taste) System: Receptors . 89 Gustatory

(Taste) System: Pathways . 90 Hypothalamus . 68 Olfactory System: Receptors . 91 Limbic System . 69 Olfactory System: Pathway . 92 NEUROPHYSIOLOGY Organization of the Brain: Cerebrum Postcentral gyrus Central sulcus (Rolando) Precentral gyrus Postcentral sulcus Precentral sulcus Superior parietal lobule Inferior parietal lobule Supramarginal gyrus Angular gyrus Parietooccipital sulcus Occipital pole Frontal pole Calcarine sulcus Lateral sulcus (Sylvius) Temporal pole Superior temporal gyrus Inferior temporal gyrus Middle temporal gyrus Frontal lobe Parietal lobe Temporal lobe Occipital lobe Insula (island of Reil) FIGURE 2.1 ORGANIZATION OF THE BRAIN: CEREBRUM• The cerebral cortex represents the highest center for sensory and motor processing. In general, the frontal lobe processes motor, visual, speech, and personality modalities. The parietal lobe processes sensory

information; the temporal lobe, auditory and memory modalities; and the occipital lobe, vision. The cerebellum 52 coordinates smooth motor activities and processes muscle position. The brainstem (medulla, pons, midbrain) conveys motor and sensory information and mediates important autonomic functions. The spinal cord receives sensory input from the body and conveys somatic and autonomic motor information to peripheral targets (muscles, viscera). NEUROPHYSIOLOGY Organization of the Brain: Cell Types Bipolar cell of cranial n. Multipolar (pyramidal) cell of cerebral motor cortex Unipolar cell of sensory ganglia of cranial nn. Satellite cells Schwann cell Astrocyte Interneurons Blood vessel Striated (somatic) muscle Motor endplate Multipolar somatic motor cell of nuclei of cranial nn. Multipolar cell of lower brain motor centers Specialized ending Muscle spindle Unipolar sensory cell of dorsal spinal root ganglion Satellite cells Interneuron Oligodendrocyte Astrocyte

Corticospinal (pyramidal) fiber Myelinated afferent fiber of spinal nerve Multipolar visceral motor (autonomic) cell of spinal cord Axodendritic ending Axosomatic ending Myelin sheath Axoaxonic ending Multipolar somatic motor cell of anterior horn of spinal cord Autonomic preganglionic (sympathetic or parasympathetic) nerve fiber Myelin sheath Autonomic postganglionic neuron of sympathetic or parasympathetic ganglion Satellite cells Unmyelinated nerve fiber Schwann cells Collateral Renshaw interneuron (feedback) Myelinated somatic motor fiber of spinal nerve Myelin sheath Red: Blue: Purple: Gray: Motor neuron Sensory neuron Interneuron Glial and neurilemmal cells and myelin Note: Cerebellar cells not shown here Schwann cells Motor endplate with Schwann cell cap Endings on cardiac muscle or nodal cells Striated (voluntary) muscle FIGURE 2.2 ORGANIZATION Free nerve endings (unmyelinated fibers) Encapsulated ending Unmyelinated fibers Free nerve endings Beaded

varicosities and endings on smooth muscle and gland cells OF THE Encapsulated ending Muscle spindle BRAIN: CELL TYPES• Neurons form the functional cellular units responsible for communication, and throughout the nervous system, they are characterized by their distinctive size and shapes (e.g, bipolar, unipolar, multipolar). Supporting cells include the neuroglia (e.g, astrocytes, oligodendrocytes), satellite cells, and other specialized cells that optimize neuronal function, provide maintenance functions, or protect the nervous system 53 NEUROPHYSIOLOGY Blood-Brain Barrier Cell membrane Basement membrane Tight junction proteins Cytoplasm Red blood cell Astrocyte foot processes Capillary lumen Tight junction Capillary endothelial cell Astrocyte FIGURE 2.3 BLOOD-BRAIN BARRIER• The blood-brain barrier (BBB) is the cellular interface between the blood and the central nervous system (CNS; brain and spinal cord). It serves to maintain the interstitial fluid

environment to ensure optimal functionality of the neurons. This barrier consists of the capillary endothelial cells with an elaborate network of tight junctions and astrocytic foot processes that abut the endothelium and its basement membrane. The movement of large molecules and 54 other substances (including many drugs) from the blood to the interstitial space of the CNS is restricted by the BBB. CNS endothelial cells also exhibit a low level of pinocytotic activity across the cell, so specific carrier systems for the transport of essential substrates of energy and amino acid metabolism are characteristic of these cells. The astrocytes help transfer important metabolites from the blood to the neurons and also remove excess K⫹ and neurotransmitters from the interstitial fluid. NEUROPHYSIOLOGY Synaptic Transmission: Morphology of Synapses Dendrite Node Dendrites Axon Myelin sheath Numerous boutons (synaptic knobs) of presynaptic neurons terminating on a motor neuron and

its dendrites Enlarged section of bouton Axon (axoplasm) Axolemma Mitochondria Glial process Synaptic vesicles Synaptic cleft Presynaptic membrane (densely staining) Postsynaptic membrane (densely staining) Postsynaptic cell FIGURE 2.4 MORPHOLOGY OF SYNAPSES• Neurons communicate with each other and with effector targets at specialized regions called synapses. The top figure shows a typical motor neuron that receives numerous synaptic contacts on its cell body and associated dendrites. Incoming axons lose their myelin sheaths, exhibit extensive branching, and terminate as synaptic boutons (synaptic terminals or knobs) on the motor neuron. The lower figure shows an enlargement of one such synaptic bouton. Chemical neurotransmitters are contained in synaptic vesicles, which can fuse with the presynaptic membrane, release the transmitters into the synaptic cleft, and then bind to receptors situated in the postsynaptic membrane. This synaptic transmission results in excitatory,

inhibitory, or modulatory effects on the target cell. 55 NEUROPHYSIOLOGY Synaptic Transmission: Neuromuscular Junction Structure of Neuromuscular Junction Active zone Myelin sheath Neurilemma Schwann cell process Axoplasm Acetylcholine receptor sites Schwann cell Mitochondria Basement membrane Nucleus of Schwann cell Presynaptic membrane Active zone Synaptic vesicles Synaptic trough Basement membrane Sarcolemma Nucleus of muscle cell Myofibrils Synaptic cleft Postsynaptic membrane Junctional fold Sarcoplasm Acetylcholine receptor sites FIGURE 2.5 STRUCTURE OF THE NEUROMUSCULAR JUNCTION• Motor axons that synapse on skeletal muscle form expanded terminals called neuromuscular junctions (motor endplates). The motor axon loses its myelin sheath and expands into a Schwann cell–invested synaptic terminal that resides within a trough in the muscle fiber. Acetylcholine-containing synaptic vesicles accumulate adjacent to the presynaptic membrane and, when appropri- 56

ately stimulated, release their neurotransmitter into the synaptic cleft. The transmitter then binds to receptors that mediate depolarization of the muscle sarcolemma and initiate a muscle action potential. A single muscle fiber has only one neuromuscular junction, but a motor axon can innervate multiple muscle fibers NEUROPHYSIOLOGY Synaptic Transmission: Visceral Efferent Endings Visceral Efferent Endings B. Gland (submandibular)                      A. Smooth muscle C. Neurosecretory (posterior pituitary) Sympathetic terminal ending Smooth muscle cells (cut) Schwann cell cap enclosing nerve axons Mucous cells Schwann cell cap enclosing nerve axons Varicosity Pituicyte processes Axon Axon Schwann cell cap Fibroblast Schwann cell cap Serous cells Smooth muscle cells Varicosities Terminal endings Parasympathetic terminal ending Schwann cell cap enclosing nerve axons Capillary Endothelium Mast cell

Varicosity Neurosecretory vesicles Collagen space Basement membrane FIGURE 2.6 VISCERAL EFFERENT ENDINGS• Neuronal efferent endings on smooth muscle (A) and glands (B and C) exhibit unique endings unlike the presynaptic and postsynaptic terminals observed in neuronal and neuromuscular junction synapses. Rather, neurotransmitter substances are released into interstitial spaces (A and B) or into the bloodstream (C, neu- rosecretion) from expanded nerve terminal endings. This arrangement allows for the stimulation of numerous target cells over a wide area. Not all smooth muscle cells are innervated They are connected to adjacent cells by gap junctions and can therefore contract together with the innervated cells. 57 NEUROPHYSIOLOGY Synaptic Transmission: Inhibitory Mechanisms I (Inhibitory fiber) E (Excitatory fiber) Motor neuron E (Excitatory fiber) Motor neuron I (Inhibitory fiber) Axon mV ⫹20 A. Only E fires 90-mV spike in E terminal EPSP in motor neuron B. Only

I fires Long-lasting partial depolarization in E terminal No response in motor neuron C. I fires before E Partial depolarization of E terminal reduces spike to 80 mV, thus releasing less transmitter substance Smaller EPSP in motor neuron Axon mV 90 mV A′. Only E fires EPSP in motor neuron ⫺70 ⫺60 ⫺70 ⫺60 ⫺70 B′. Only I fires Motor neuron hyperpolarized ⫺60 ⫺70 ⫺70 ⫺70 ⫺80 C′. I fires before E ⫹20 80 mV Depolarization of motor neuron less than if only E fires ⫺60 ⫺70 ⫺80 ⫺70 ⫺60 ⫺70 FIGURE 2.7 SYNAPTIC INHIBITORY MECHANISMS• Inhibitory synapses modulate neuronal activity. Illustrated here is presynaptic inhibition (left panel) and postsynaptic inhibition (right panel) at a motor neuron. 58 NEUROPHYSIOLOGY Synaptic Transmission: Chemical Synaptic Transmission               Inhibitory Excitatory Synaptic vesicles in synaptic bouton Presynaptic membrane

 Na


 K



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



 Cl At inhibitory synapse, transmitter substance released by an impulse increases permeability of the postsynaptic membrane to Cl. K
moves out of post-synaptic cell but no net flow of Cl occurs at resting membrane potential Synaptic bouton Potential (mV) Current 65 70 Potential 0 Resultant ionic current flow is in direction that tends to hyperpolarize postsynaptic cell. This makes depolarization by excitatory synapses more difficultmore depolarization is required to reach threshold msec 0 4 8 12 16 70 Potential (mV) Resultant net ionic current flow is in a direction that tends to depolarize postsynaptic

cell. If depolarization reaches firing threshold, an impulse is generated in postsynaptic cell 8 12 16 msec Current flow and potential change Potential 75 Current 4 Current flow and potential change FIGURE 2.8 CHEMICAL SYNAPTIC TRANSMISSION• Chemical synaptic transmission between neurons may be excitatory or inhibitory. During excitation (left column), a net increase in the inward flow of Na
compared with the outward flow of K
results in a depolarizing potential change (excitatory postsynaptic potential [EPSP]) that drives the postsynaptic cell closer to its threshold for an action potential. During inhibition (right column), the opening of K
and Cl channels drives the membrane potential away from threshold (hyperpolarization) and decreases the probability that the neuron will reach threshold (inhibitory postsynaptic potential [IPSP]) for an action potential. 59 NEUROPHYSIOLOGY Synaptic Transmission: Temporal and Spatial Summation Temporal and Spatial Summation

of Excitation and Inhibition Excitatory fibers mV mV Excitatory fibers –70 –70 Axon Axon Inhibitory fibers Inhibitory fibers A. Resting state: motor nerve cell shown with synaptic boutons of excitatory and inhibitory nerve fibers ending close to it B. Partial depolarization: impulse from one excitatory fiber has caused partial (below firing threshold) depolarization of motor neuron mV Excitatory fibers mV Excitatory fibers –70 –70 Axon Axon Inhibitory fibers Inhibitory fibers C. Temporal excitatory summation: a series of impulses in one excitatory fiber together produce a suprathreshold depolarization that triggers an action potential mV Excitatory fibers D. Spatial excitatory summation: impulses in two excitatory fibers cause two synaptic depolarizations that together reach firing threshold triggering an action potential mV Excitatory fibers –70 –70 Axon Axon Inhibitory fibers Inhibitory fibers E. Spatial excitatory summation with inhibition:

impulses from two excitatory fibers reach motor neuron but impulses from inhibitory fiber prevent depolarization from reaching threshold E. (continued): motor neuron now receives additional excitatory impulses and reaches firing threshold despite a simultaneous inhibitory impulse; additional inhibitory impulses might still prevent firing CHART 2.1 SUMMARY OF SOME NEUROTRANSMITTERS AND WHERE WITHIN THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM THEY ARE FOUND Transmitter Acetylcholine Biogenic amines Norepinephrine Dopamine Serotonin Amino acids ␥-Aminobutyric acid (GABA) Glutamate Purines Adenosine Adenosine triphosphate (ATP) Location Neuromuscular junction, autonomic endings and ganglia, CNS Sympathetic endings, CNS CNS CNS, GI tract CNS CNS CNS CNS Transmitter Gas Nitric oxide Peptides ␤-Endorphins Enkephalins Antidiuretic hormone Pituitary-releasing hormones Somatostatin Neuropeptide Y Vasoactive intestinal peptide Location CNS, GI tract CNS, GI tract CNS CNS

(hypothalamus/posterior pituitary) CNS (hypothalamus/anterior pituitary) CNS, GI tract CNS CNS, GI tract CNS, Central nervous system; GI, gastrointestinal. FIGURE 2.9 TEMPORAL AND SPATIAL SUMMATION • Neurons receive multiple excitatory and inhibitory inputs. Temporal summation occurs when a series of subthreshold impulses in one excitatory fiber produces an action potential in the postsynaptic cell (panel C). Spatial summation occurs when subthreshold impulses from two or more different fibers trigger an action poten- 60 tial (panel D). Both temporal and spatial summation can be modulated by simultaneous inhibitory input (panel E) Inhibitory and excitatory neurons use a wide variety of neurotransmitters, some of which are summarized here. Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition NEUROPHYSIOLOGY Left lateral phantom view Frontal (anterior) horn Right lateral ventricle Central part Temporal (inferior) horn Left lateral ventricle Occipital

(posterior) horn Cerebral aqueduct (Sylvius) 4th ventricle Left lateral aperture (foramen of Luschka) Left lateral recess Left interventricular foramen (Monro) Median aperture (foramen of Magendie) 3rd ventricle Central canal of spinal cord CHART 2.2 CSF COMPOSITION Na⫹ (mEq/L) K⫹ (mEq/L) Cl− (mEq/L) HCO3− (mEq/L) Glucose (mg/dL) Protein (g/dL) pH FIGURE 2.10 BRAIN VENTRICLES AND CSF 140–145 3 115–120 20 50–75 0.05–007 7.3 Blood Plasma 135–147 3.5–50 95–105 22–28 70–110 6.0–78 7.35–745 CSF COMPOSITION• CSF circulates through the four brain ventricles (two lateral ventricles and a third and fourth ventricle) and in the subarachnoid space surrounding the brain and spinal cord. The electrolyte composition of the CSF is regulated by the choroid plexus, which secretes the CSF. Importantly, the CSF has a lower [HCO3⫺] than plasma and therefore a lower pH. This allows small changes in blood PCO2 to cause changes in CSF pH, which in turn

regulates the rate of respiration (see Chapter 5). 61 NEUROPHYSIOLOGY Cerebrospinal Fluid (CSF): Circulation of CSF Choroid plexus of lateral ventricle (phantom) Superior sagittal sinus Subarachnoid space Cistern of corpus callosum Arachnoid granulations Dura mater Arachnoid Interventricular foramen (Monro) Choroid plexus of 3rd ventricle Cerebral aqueduct (Sylvius) Lateral aperture (foramen of Luschka) Choroid plexus of 4th ventricle Dura mater Median aperture (foramen of Magendie) Arachnoid Subarachnoid space Central canal of spinal cord FIGURE 2.11 CIRCULATION OF CEREBROSPINAL FLUID• CSF circulates through the four brain ventricles (two lateral ventricles and a third and fourth ventricle) and in the subarachnoid space surrounding the brain and spinal cord. Most of the CSF is 62 reabsorbed into the venous system through the arachnoid granulations and through the walls of the capillaries of the central nervous system and pia mater. NEUROPHYSIOLOGY Spinal

Cord: Ventral Rami Base of skull C1 vertebra (atlas) C1 spinal nerve Cervical plexus C8 spinal nerve Brachial plexus T1 spinal nerve Spinal dura mater 1st rib Filaments of spinal nerve roots (T7 and T8) Intercostal nerves T12 spinal nerve L1 vertebra 12th rib Conus medullaris Lumbar plexus L1 spinal nerve L5 vertebra Cauda equina S1 spinal nerve Sacral plexus Sacrum (cut away) Termination of dural sac Sciatic nerve Coccygeal nerve Coccyx FIGURE 2.12 SPINAL CORD AND VENTRAL RAMI IN SITU• The spinal cord gives rise to 31 pairs of spinal nerves that distribute segmentally to the body. These nerves are organized into plexuses that distribute to the neck (cervical plexus), upper limb (brachial plexus), and pelvis and lower limb (lumbosacral plexus). Motor fibers of these spinal nerves innervate skeletal muscle, and sensory fibers convey information back to the central nervous system from the skin, skeletal muscles, and joints. 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 segmentally to the body. Motor fibers of these spinal nerves innervate skeletal muscle, and sensory fibers convey information back to the central nervous system from the skin, skeletal muscles, and joints. 64 The spinal cord is

ensheathed in three meningeal coverings: the outer, tough dura mater; the arachnoid mater; and the pia mater, which intimately ensheaths the cord itself. CSF bathes the cord and is found in the subarachnoid space. NEUROPHYSIOLOGY Peripheral Nervous System Posterior horn Dorsal root ganglion Sensory neuron cell body Dorsal root Anterior horn Motor neuron cell body Ventral root Peripheral nerve Axon Myelin sheath Motor neuron Sensory neuron Neuromuscular junction Skin Muscle with FIGURE 2.14 PERIPHERAL NERVOUS SYSTEM• The peripheral nervous system (PNS) consists of all of the neural elements outside of the CNS (brain and spinal cord) and provides the connections between the CNS and all other body organ systems. The PNS consists of somatic and autonomic components The somatic component innervates skeletal muscle and skin and is shown here (see Figure 2.15 for the autonomic nervous system) The somatic component of the peripheral nerves contains both motor and sensory

axons. Cell bodies of the motor neurons are found in the anterior horn gray matter, whereas the cell bodies of sensory neurons are located in the dorsal root ganglia. 65 NEUROPHYSIOLOGY Autonomic Nervous System: Schema Intracranial vessels Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) Medulla oblongata Vagus nerve (X) Pterygopalatine ganglion Lacrimal glands Otic ganglion Parotid glands mi Gray ra ntes nica u m m o c C1 C2 C3 C4 C5 C6 C7 C8 Sweat gland Ciliary ganglion Eye Submandibular ganglion Sublingual and submandibular glands Peripheral cranial and facial vessels Larynx Trachea Bronchi Lungs T1 Gray and white rami communican tes Peripheral blood vessel Pulmonary plexus T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 Heart Greater  Splanchnic Lesser  nerves Least  Celiac ganglion Stomach Lumbar splanchnic nerves Pancreas Suprarenal glands Kidneys m uni cantes Intestines L5 Inferior mesenteric ganglion Superior hypogastric plexus Sigmoid

colon Rectum Urinary bladder a mi ay r S2 S3 S4 S5 Coccygeal Superior mesenteric ganglion Descending colon co m S1 Gr Note: Blue-shaded areas indicate zones of parasympathetic outflow from CNS Aorticorenal ganglion Liver Gallbladder Bile ducts Arrector (smooth) T12 muscle of hair follicle Note: Above three L1 structures are shown at L2 only one level but occur at all levels L3 L4 Cardiac plexus Pelvic splanchnic nerves Inferior hypogastric plexus Prostate External genitalia Sympathetic fibers Presynaptic Postsynaptic Parasympathetic fibers Presynaptic Postsynaptic Antidromic conduction FIGURE 2.15 AUTONOMIC NERVOUS SYSTEM: SCHEMA• The autonomic nervous system is composed of two divisions: the parasympathetic division derived from four of the cranial nerves (CN III, VII, IX, and X) and the S2-S4 sacral spinal cord levels, and the sympathetic division associated with the thoracic and upper lumbar spinal cord levels (T1-L2). The autonomic nervous system is a

twoneuron chain, with the preganglionic neuron arising from the central nervous system and synapsing on a postganglionic neuron located in 66 a peripheral autonomic ganglion. Postganglionic axons of the autonomic nervous system innervate smooth muscle, cardiac muscle, and glands. Basically, the sympathetic division mobilizes our body (“fight or flight”) while the parasympathetic division regulates digestive and homeostatic functions. Normally, both divisions work in concert to regulate visceral activity (respiration, cardiovascular function, digestion, and associated glandular activity). Autonomic Nervous System: Cholinergic and Adrenergic Synapses Parotid gland Glossopharyngeal nerve (IX) Medulla oblongata NEUROPHYSIOLOGY Internal carotid nerve Vagus nerve (X) Larynx Trachea Bronchi Lungs Heart Cervical sympathetic ganglia Striated muscle Sweat glands White ramus communicans Gray ramus communicans Thoracic part of spinal cord Celiac ganglion Peripheral arteries

Superior mesenteric ganglion Upper lumbar part of spinal cord (L1-2 [3]) Hair follicles Visceral arteries Gastrointestinal tract Suprarenal gland Inferior mesenteric ganglion Pelvic splanchnic nerves Sacral part of spinal cord Urinary bladder Urethra Prostate C Cholinergic synapses A Adrenergic synapses Sympathetic fibers Presynaptic Parasympathetic fibers Postsynaptic Presynaptic Postsynaptic Somatic fibers Antidromic conduction FIGURE 2.16 CHOLINERGIC AND ADRENERGIC SYNAPSES: SCHEMA• The autonomic nervous system (ANS) is a two-neuron chain, with the preganglionic neuron arising from the central nervous system and synapsing on a postganglionic neuron located in a peripheral autonomic ganglion. Acetylcholine is the neurotransmitter in both the sympathetic and parasympathetic ganglia. The parasympathetic division of the ANS releases acetylcholine at its postganglionic synapses and is characterized as having cholinergic (C) effects, whereas the sympathetic division

releases predominantly noradren- aline (norepinephrine) at its postganglionic synapses, causing adrenergic (A) effects (except on sweat glands, where acetylcholine is released). Although acetylcholine and noradrenaline are the chief transmitter substances, other neuroactive peptides often are colocalized with them and include such substances as gammaaminobutyric acid (GABA), substance P, enkephalins, histamine, glutamic acid, neuropeptide Y, and others. 67 NEUROPHYSIOLOGY Hypothalamus Corpus callosum Septum pellucidum Fornix Lateral ventricle From hippocampal formation Thalamus Interthalamic Lateral adhesion hypothalamic area Paraventricular nucleus Medial Anterior hypothalamic area Anterior forebrain commissure Dorsal hypothalamic area bundle Dorsomedial nucleus Mamillothalamic tract Posterior area Lateral Periventricular preoptic Medial nucleus nucleus preoptic Nucleus intercalatus nucleus Olfactory tract Optic (II) nerve Optic chiasm Fornix Red nucleus Ventromedial

Mamillary nucleus complex Tuberohypophyseal tract Oculomotor (III) nerve Supraoptic nucleus Supraopticohypophyseal tract Posterior lobe of pituitary Anterior lobe of pituitary Cerebral peduncle Dorsal longitudinal fasciculus Descending hypothalamic connections Pons Reticular formation CHART 2.3 MAJOR FUNCTIONS OF THE HYPOTHALAMUS Hypothalamic Area Preoptic and anterior Posterior Lateral Ventromedial Supraoptic (subfornical organ and organum vasculosum) Paraventricular Periventricular Major Functions* Heat loss center: cutaneous vasodilation and sweating Heat conservation center: cutaneous vasoconstriction and shivering Feeding center: eating behavior Satiety center: inhibits eating behavior ADH and oxytocin secretion (sensation of thirst) ADH and oxytocin secretion Releasing hormones for the anterior pituitary *Stimulation of the center causes the responses listed. FIGURE 2.17 SCHEMATIC RECONSTRUCTION OF THE HYPOTHALAMUS• The hypothalamus, part of the diencephalon,

controls a number of important homeostatic systems within the body, including temperature regulation, food intake, water intake, many of the endocrine systems (see Chapter 8), motivation, and emotional behavior. It receives inputs from the reticular formation (sleep/wake cycle 68 information), the thalamus (pain), the limbic system (emotion, fear, anger, smell), the medulla oblongata (blood pressure and heart rate), and the optic system, and it integrates these inputs for regulation of the functions listed. NEUROPHYSIOLOGY Limbic System Genu of corpus callosum Head of caudate nucleus Columns of fornix Body of fornix Thalamus Uncus Crura of fornix Fimbria of hippocampus Hippocampus Commissure of fornix Splenium of corpus callosum Lateral ventricle Body of fornix Columns of fornix Commissure of fornix Crura of fornix Mamillary bodies Amygdaloid bodies FIGURE 2.18 HIPPOCAMPUS AND Hippocampus with fimbria FORNIX• The limbic system includes the hypothalamus and a

collection of interconnected structures in the telencephalon (cingulate, parahippocampal, and subcallosal gyri), as well as the amygdala and hip- pocampal formation. The limbic system functions in linking emotion and motivation (amygdala), learning and memory (hippocampal formation), and sexual behavior (hypothalamus) 69 NEUROPHYSIOLOGY The Cerebral Cortex Motor Premotor; orientation; eye and head movements Sm I Sensory Sm II Ms I Ms II Sensory analysis Prefrontal; inhibitory control of behavior; higher intelligence Visual III Visual II Visual I Language; reading; speech Auditory I Motor control of speech Auditory II Motor Sm I Sensory Sm III ? Ms I Ms II Premotor Prefrontal; inhibitory control of behavior; higher intelligence Visual III Visual II Visual I Cingulate gyrus (emotional behavior) and cingulum Corpus callosum Hippocampal commissure Olfactory FIGURE 2.19 CEREBRAL CORTEX: LOCALIZATION Anterior commissure OF FUNCTION The cerebral cortex is

organized into functional regions. In addition to specific areas devoted to sensory and motor functions, there are areas that integrate information from multiple sources. The cerebral cortex participates in advanced intellectual functions, 70 AND ASSOCIATION PATHWAYS• including aspects of memory storage and recall, language, higher cognitive functions, conscious perception, sensory integration, and planning/execution of complex motor activity. General cortical areas associated with these functions are illustrated. NEUROPHYSIOLOGY Hip Knee Ankle Motor cortex Internal capsule Trunk Shoulder Elbow W Fin rist ge rs Descending Motor Pathways b um Th eck N Browd Eyeli Nares Lips Tongue Larynx Toes Lateral aspect of cerebral cortex to show topographic projection of motor centers on precentral gyrus Midbrain Basis pedunculi Pons Motor system Fibers originate in motor cortex and descend via posterior limb of internal capsule to basis pedunculi of midbrain Longitudinal

bundles branch upon entering basis pontis and rejoin to enter pyramids of medulla Basis pontis Medulla Pyramids Medulla Decussation of pyramids At lower medulla, bulk of fibers cross median plane to form lateral corticospinal tract; some fibers continue downward in ipsilateral lateral corticospinal tract; others descending ipsilateral anterior corticospinal tract Synapse occurs at spinal level: Lateral corticospinal fibers synapse on ipsilateral anterior horn cells; anterior corticospinal fibers synapse on contralateral anterior horn cells Above midthoracic level Spinal cord Below midthoracic level Motor endplate Anterior corticospinal tract Lateral corticospinal tract Motor endplate FIGURE 2.20 CORTICOSPINAL TRACTS• The corticospinal, or pyramidal, tract is the major motor tract that controls voluntary movement of the skeletal muscles, especially skilled movements of distal muscles of the limbs. All structures from the cerebral cortex to the anterior horn cells in the

spinal cord constitute the upper portion of the system (upper motor neuron). The anterior horn cells and their associated axons constitute the lower portion of the system (lower motor neuron). 71 NEUROPHYSIOLOGY Cerebellum: Afferent Pathways Superior cerebellar peduncle Middle cerebellar peduncle To contralateral cerebellar cortex Cortical input Leg Nucleus reticularis tegmenti pontis Arm Fac e Primary fissure Pontine nuclei (contralateral) Spinal input Inferior olive Upper part of medulla oblongata Spinal input Vestibular nerve and ganglion Lower part of medulla oblongata Cortical input Lateral reticular nucleus Spinal input Cervical part of spinal cord Motor interneuron Rostral spinocerebellar tract Spinal border cells Motor interneuron Lumbar part of spinal cord Clarke’s column Ventral spinocerebellar tract Vestibular nuclei To nodule and flocculus Inferior cerebellar peduncle Reticulocerebellar tract Cuneocerebellar tract Gracile nucleus Main cuneate nucleus

(relay for cutaneous information) External cuneate nucleus (relay for proprioceptive information) From skin (touch and pressure) From muscle (spindles and Golgi tendon organs) From skin and deep tissues (pain and Golgi tendon organs) From skin (touch and pressure) and from muscle (spindles and Golgi tendon organs) Dorsal spinocerebellar tract Functional Subdivisions of Cerebellum Hemisphere Vermis InterLateral mediate part part Anterior lobe Leg zone Primary Arm zone fissure Face zone Middle (posterior) lobe 2nd spinal projection area (gracile lobule) ArchiLingula cerebellum Flocculus (vestibulocerebellum) Nodule Paleocerebellum Uvula (spinocerebellum) Pyramid Vermis Neocerebellum Middle vermis (pontocerebellum) Hemisphere Posterolateral fissure Flocculonodular lobe Schema of theoretical “unfolding” of cerebellar surface in derivation of above diagram FIGURE 2.21 CEREBELLAR AFFERENT PATHWAYS• The cerebellum plays an important role in coordinating movement. It receives

sensory information and then influences descending motor pathways to produce fine, smooth, and coordinated motion. The cerebellum is divided into three general areas: archicerebellum (also called vestibulocerebellum) paleocerebellum (also called spinocerebellum) and the neocerebellum (also called the cerebrocerebellum). The archicerebellum is primarily involved in controlling posture and balance, as well as the movement of the head and eyes. It receives afferent signals from the vestibular apparatus and then sends efferent fibers to the appropriate descending motor pathways. The paleocere- 72 bellum primarily controls movement of the proximal portions of the limbs. It receives sensory information on limb position and muscle tone and then modifies and coordinates these movements through efferent pathways to the appropriate descending motor pathways. The neocerebellum is the largest portion of the cerebellum, and it coordinates the movement of the distal portions of the limbs. It

receives input from the cerebral cortex and thus helps in the planning of motor activity (e.g, seeing a pencil and then planning and executing the movement of the arm and hand to pick it up). NEUROPHYSIOLOGY Cerebellum: Efferent Pathways Excitatory endings Motor and premotor cerebral cortex Inhibitory endings of Purkinje cells Internal capsule Ventral anterior and ventral lateral nuclei of thalamus Cerebral peduncle Mesencephalic reticular formation Red nucleus Fastigial nucleus Globose nuclei Decussation of superior cerebellar peduncles Descending fibers from superior cerebellar peduncles Hook bundle of Russell Emboliform nucleus Dentate nucleus Section A–B viewed from below Cerebellar cortex Section B–C viewed from above Vestibular nuclei Inferior cerebellar peduncle Inferior olive Lateral reticular nucleus Medulla oblongata Pontomedullary reticular formation A Planes of section: red arrows indicate C direction of view B FIGURE 2.22 CEREBELLAR EFFERENT

PATHWAYS• The cerebellum plays an important role in coordinating movement. It influences descending motor pathways to produce fine, smooth, and coordinated motion. The archicerebellum is primarily involved in controlling posture and balance and movement of the head and eyes. It sends efferent fibers to the appropriate descending motor pathways. The paleocerebellum primarily controls movement of the proximal portions of the limbs. It modifies and coordinates these movements through efferent pathways to the appropriate descending motor pathways. The neocerebellum coordinates the movement of the distal portions of the limbs. It helps in the planning of motor activity (eg, seeing a pencil and then planning and executing the movement of the arm and hand to pick it up). 73 NEUROPHYSIOLOGY Cutaneous Sensory Receptors Free nerve endings Hair shaft Meissner’s corpuscle Pore of sweat gland Stratum granulosum Stratum spinosum Stratum basale Internal sheath Hair follicle

Epidermis Melanocyte Arrector muscle of hair Sebaceous gland Cuticle Stratum corneum Stratum lucidum External sheath Glassy membrane Connective tissue layer Dermis Dermal papilla (of papillary layer) Reticular layer Hair cuticle Sweat gland Subcutaneous tissue Hair matrix Papilla of hair follicle Pacinian corpuscle Artery Subcutaneous artery and vein Vein Sensory nerves Elastic fibers Detail of Merkel’s disc Basal epithelial cells Skin ligaments (retinacula cutis) Desmosomes Motor (autonomic) nerve Cross section Lobulated nucleus Mitochondria Granulated vesicles Expanded axon terminal Schwann cell AND Axon Schwann cells Detail of free nerve ending CUTANEOUS RECEPTORS• Cutaneous receptors respond to touch (mechanoreceptors), pain (nociceptors), and temperature (thermoreceptors). Several different types of receptors are present in skin. Meissner’s corpuscles have small receptive fields and respond best to stimuli that are applied at low frequency (i.e,

flutter) The pacinian corpuscles are located in the subcutaneous tissue and have large receptive fields. They 74 Cutaneous nerve Merkel cell Cytoplasmic protrusion FIGURE 2.23 SKIN Basement membrane Axon terminal Mitochondrion Schwann cell respond best to high-frequency stimulation (i.e, vibration) Merkel’s discs have small receptive fields and respond to touch and pressure (i.e, indenting the skin) Ruffini’s corpuscles have large receptive fields, and they also respond to touch and pressure. Free nerve endings respond to pain and temperature. NEUROPHYSIOLOGY Cutaneous Receptors: Pacinian Corpuscle Pacinian Corpuscle as Pressure Transducer Pressure To amplifier Generator potential Action potential A. Sharp “on and off” changes in pressure at start and end of pulse applied to lamellated capsule are transmitted to central axon and provoke generator potentials, which in turn may trigger action potentials; there is no response to a slow change in pressure

gradient. Pressure at central core and, accordingly, generator potentials are rapidly dissipated by viscoelastic properties of capsule (Action potentials may be blocked by pressure at a node or by drugs) 1st node Myelin sheath Lamellated capsule Central core Unmyelinated axon terminal Pressure To amplifier Generator potential B. In absence of capsule, axon responds to slow as well as to rapid changes in pressure. Generator potential dissipates slowly, and there is no “off” response Na+ Pressure ⴙ ⴙ ⴚ ⴚ Action potential ⴚ ⴙ ⴚ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴙ Pressure applied to axon terminal directly or via capsule causes increased permeability of membrane to Na+, thus setting up ionic generator current through 1st node ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴙ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴚ ⴙ ⴙ ⴙ ⴙ ⴚ ⴚ ⴚ ⴚ ⴚ If resultant

depolarization at 1st node is great enough to reach threshold, an action potential appears which is propagated along nerve fiber FIGURE 2.24 PACINIAN CORPUSCLE• Pacinian corpuscles are mechanoreceptors that transduce mechanical forces (displacement, pressure, vibration) into action potentials that are conveyed centrally by afferent nerve fibers. As the viscoelastic lamellae are displaced, the unmyelinated axon terminal membrane’s ionic permeability is increased until it is capable of producing a “generator potential.” As demonstrated in the figure, pacinian corpuscles respond to the beginning and end of a mechanical force while the concentric lamellae dissipate slow changes in pressure. In the absence of the capsule, the generator potential decays slowly and yields only a single action potential. 75 NEUROPHYSIOLOGY Proprioception and Reflex Pathways: I Spinal Effector Mechanisms Dorsal horn interneuron From motor neuron From cutaneous receptor Proprioceptive

fibers Dorsal horn interneuron From muscle spindle Flexor reflex interneuron Dorsal horn interneuron Dorsal root ganglion To motor neuron Ventral root To motor neuron ␣ motor axon Schematic representation of motor neurons E xt e r n so s Fl e x o rs o rs so Flex In lumbar enlargement of spinal cord rs In cervical enlargement of spinal cord Ext e n FIGURE 2.25 PROPRIOCEPTION: SPINAL EFFECTOR MECHANISM• Position sense or proprioception involves input from cutaneous mechanoreceptors, Golgi tendon organs, and muscle spindles (middle figure of upper panel). Both monosynaptic reflex pathways (middle figure of upper panel) and polysynaptic pathways involving several spinal cord segments (top and bottom figures of upper 76 panel) initiate muscle contraction reflexes. The lower panel shows the somatotopic distribution of the motor neuron cell bodies in the ventral horn of the spinal cord that innervate limb muscles (flexor and extensor muscles of upper and lower

limbs). NEUROPHYSIOLOGY Proprioception and Reflex Pathways: II Alpha motor neurons to extrafusal striated muscle end plates Gamma motor neurons to intrafusal striated muscle end plates Ia (A␣) fibers from annulospiral endings (proprioception) II (A␤) fibers from flower spray endings (proprioception); from paciniform corpuscles (pressure) and pacinian corpuscles (pressure) III (A␦) fibers from free nerve endings and from some specialized endings (pain and some pressure) IV (unmyelinated) fibers from free nerve endings (pain) Ib (A␣) fibers from Golgi tendon organs (proprioception) A␣ fibers from Golgi-type endings A␤ fibers from paciniform corpuscles and Ruffini terminals Alpha motor neuron to extrafusal muscle fiber end plates A␦ and C fibers from free nerve endings Gamma motor neuron to intrafusal muscle fiber and plates II (A␤) fiber from flower spray endings Extrafusal muscle fiber Ia (A␣) fiber from annulospiral endings Intrafusal muscle fibers Sheath

Lymph space Nuclear bag fiber Nuclear chain fiber Detail of muscle spindle FIGURE 2.26 MUSCLE AND JOINT Efferent fibers Afferent fibers RECEPTORS• Muscle spindles and Golgi tendon organs send afferent signals to the brain to convey the position of limbs and help coordinate muscle movement. Muscle spindles convey information on muscle tension and contraction (dynamic forces) and muscle length (static forces). The nuclear bag fibers respond to both dynamic and static forces, whereas the nuclear chain fibers respond to static forces. Intrafusal fibers maintain appropriate tension on the nuclear bag and nuclear chain fibers. If the muscle tension is too great (eg, overstretching of muscle or too heavy a load), activation of the Golgi tendon organ causes a reflex relaxation of the muscle. 77 NEUROPHYSIOLOGY Proprioception and Reflex Pathways: III Ib fibers Ia fibers ⫹⫹⫹⫹ Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons ⫹⫹⫹ Gamma motor

neurons Golgi tendon organ A. Passive stretch Both intrafusal and extrafusal muscle fibers stretched; spindles activated. Reflex via Ia fibers and alpha motor neurons causes secondary contraction (basis of stretch reflexes, such as knee jerk). Stretch is too weak to activate Golgi tendon organs Ib fibers ⫹⫹ Alpha activation from brain Ia fibers Extrafusal muscle fiber Intrafusal muscle fiber Inhibitory interneuron Alpha motor neurons ⫹⫹ Gamma motor neurons Golgi tendon organ B. Active contraction Central excitation of alpha motor neurons only causes contraction of extrafusal muscle fibers with consequent relaxation of intrafusal fibers; spindles not activated. Tension is low; does not adjust to increased resistance. Tendon organ activated, causing relaxation Alpha and gamma Ib fibers ⫹⫹⫹ activation from brain Ia fibers ⫹⫹⫹⫹ Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons ⫹⫹⫹⫹ Gamma motor neurons ⫹⫹⫹⫹ Golgi tendon organ C.

Active contraction with gamma coactivation Intrafusal as well as extrafusal fibers contract; spindles activated, reinforcing contraction stimulus via Ia fibers in accord with resistance. Tendon organ activated, causing relaxation if load is too great FIGURE 2.27 PROPRIOCEPTIVE REFLEX CONTROL OF MUSCLE TENSION• Interaction of the muscle spindle and Golgi tendon organ during passive stretch of a muscle (panel A) and during a contraction (panels B and C). 78 NEUROPHYSIOLOGY Proprioception and Reflex Pathways: IV B. Stretch reflex (reciprocal inhibition) A. Afferent inhibition From extensor spindle receptor (Ia, II fibers) From extensor spindle receptor (Ia, II fibers) From flexor spindle (Ia, II fibers) Axosomatic or axodendritic inhibitory synapse Axoaxonic presynaptic inhibitory synapse Excitatory synapse To extensors To extensors To flexors C. Recurrent inhibition D. Tendon organ reflex From extensor tendon organ (Ib fibers) Inhibitory synapse Renshaw cells

Excitatory synapse Collaterals To extensors To synergistic muscles To flexors E. Flexor withdrawal reflex Nociceptive fibers Ipsilateral flexion Contralateral extension Inhibitory synapse Excitatory synapse Excitatory synapse Inhibitory synapse To extensors To flexors To extensors To flexors FIGURE 2.28 SPINAL REFLEX PATHWAYS• Summary of the spinal reflex pathways. 79 NEUROPHYSIOLOGY Sensory Pathways: I Cerebral cortex: postcentral gyrus Posterior limb of internal capsule Ventral posterolateral (VPL) nucleus of thalamus Mesencephalon (cerebral peduncles) Medial lemniscus Gracile nucleus Spinothalamic tract Cuneate nucleus Lower part of medulla oblongata Fasciculus gracilis Fasciculus cuneatus Reticular formation Dorsal (posterior) spinal root ganglion Proprioception, position Cervical part of spinal cord Touch, pressure, vibration Lateral spinothalamic tract: pain, temperature Pain, temperature Spinocervical tract Lumbar part of spinal cord OF THE

BODY• Pain, temperature, and pressure sensations below the head ultimately are conveyed to the primary somatosensory cortex (postcentral gyrus) by the anterolateral system (spinothalamic and spinoreticular tracts). The fasciculus gracilis and cuneatus of the spinal lemniscal system convey proprioceptive, vibratory, and tactile sen- 80 Small myelinated and unmyelinated fibers Lateral cervical nucleus Ventral (anterior) spinothalamic tract: touch, pressure FIGURE 2.29 SOMESTHETIC SYSTEM Large myelinated fibers sations to the thalamus (ventral posterolateral nucleus), whereas the lateral cervical system mediates some touch, vibratory, and proprioceptive sensations (blue and purple lines show these dual pathways). Ultimately, these fibers ascend as parallel pathways to the thalamus, synapse, and ascend to the cortex. NEUROPHYSIOLOGY Sensory Pathways: II Cerebral cortex: postcentral gyrus Ventral posteromedial (VPM) nucleus of thalamus Internal capsule Midbrain (cerebral

peduncles) Dorsal trigeminal lemniscus Trigeminal mesencephalic nucleus Trigeminal motor nucleus Principal sensory trigeminal nucleus Touch, pressure Pain, temperature Proprioception Ventral trigeminal lemniscus Pontine reticular formation Trigeminal (semilunar) ganglion Ophthalmic n. Maxillary n. Pons Sensory root and Motor root of mandibular n. Medullary reticular formation Spinal trigeminal tract Spinal trigeminal nucleus Cervical part of spinal cord Facial (VII) n. Vagus (X) n. Dorsolateral fasciculus (of Lissauer) Substantia gelatinosa (Iamina II) FIGURE 2.30 SOMESTHETIC SYSTEM OF THE HEAD• Nerve cells bodies for touch, pressure, pain, and temperature in the head are in the trigeminal (semilunar) ganglion of the trigeminal (CN V) nerve (blue and red lines in figure). Neuronal cell bodies mediating proprioception reside in the mesencephalic nucleus of CN V (purple fibers). Most relay neurons project to the contralateral VPM nucleus of the thalamus and thence to the

postcentral gyrus of the cerebral cortex, where they are somatotopically represented. 81 NEUROPHYSIOLOGY Sensory Pathways: III Schematic demarcation of dermatomes shown as distinct segments. There is actually considerable overlap between any two adjacent dermatomes C2 C3 C4 C5 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 C2 C3 C4 C5 C6 C7 C8 C6 C6 T1 C5 C8 C7 C6 C8 C7 C7 S2, 3 L2 C8 S3 S4 S5 L3 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S1 S2 S1 S2 L5 L1 L4 L2 L3 L5 S1 S2 L4 S1 S1 L5 L5 L4 L4 Levels of principal dermatomes Clavicles C5 C5, 6, 7 Lateral parts of upper limbs Medial sides of upper limbs C8, T1 Thumb C6 C6, 7, 8 Hand Ring and little fingers C8 Level of nipples T4 T10 T12 L1, 2, 3, 4 L4, 5, S1 L4 S1, 2, L5 S1 S2, 3, 4 Level of umbilicus Inguinal or groin regions Anterior and inner surfaces of lower limbs Foot Medial side of great toe Posterior and outer surfaces of lower limbs Lateral margin of foot and little toe Perineum FIGURE

2.31 DERMATOMES• Sensory information below the head is localized to specific areas of the body, which reflect the distribution of peripheral sensory fibers that convey sensations to the spinal cord through the dorsal roots (sensory nerve cell bodies reside in the corresponding dorsal root ganglion). The area of skin subserved by afferent fibers of one 82 dorsal root is called a dermatome. This figure shows the dermatome segments and lists key dermatome levels used by clinicians Variability and overlap occur, so all dermatome segments are only approximations. NEUROPHYSIOLOGY Visual System: Receptors B. Section through retina A. Eyeball Iris Lens Axons at surface of retina passing via optic nerve, chiasm, and tract to lateral geniculate body Cornea Suspensory ligament Ciliary body Anterior chamber Inner limiting membrane Ganglion cell Posterior chamber Müller cell (supporting glial cell) Amacrine cell Bipolar cell Horizontal cell Rod Cone Pigment cells of

choroid Ora containing serrata aqueous humor Vitreous humor Retina Choroid Sclera Fovea Optic nerve Synaptic ending fully polarized Synaptic ending depolarized C. Rod in dark D. Rod in light Photons of light Rhodopsin Metabolic energy Current flow Na+ permeability increased Retinene + Opsin Vitamin A Synaptic bar Nucleus Lumirhodopsin Metarhodopsin Retinene + Opsin Vitamin A Centriole (basal body) Na+ permeability decreased Circulation FIGURE 2.32 VISUAL RECEPTORS• The rods and cones of the retina transduce light into electrical signals. As illustrated for the rod, light is absorbed by rhodopsin, and through the second messenger cGMP (not shown), Na⫹ channels in the membrane close and the cell hyperpolarizes. Thus, in the dark the cell is depolarized, but it is hyperpolarized in the light. This electrical response to light is distinct from other receptor responses, in which the response to a stimulus results in a depolarization of the receptor cell membrane. 83

NEUROPHYSIOLOGY Visual System: Visual Pathway Central darker circle represents macular zone G G Overlapping visual fields A Lightest shades represent monocular fields A B B H H Each quadrant a different color R RC P Choroid C Projection on left retina Projection on right retina Optic (II) nerves Optic chiasm P Choroid Periphery Macula Structure of retina (schematic): Projection on left A Amacrine cells dorsal lateral B Bipolar cells geniculate nucleus C Cones G Ganglion cells H Horizontal cells P Pigment cells R Rods Optic tracts Projection on right dorsal lateral geniculate nucleus Lateral geniculate bodies Calcarine fissure Projection on left occipital lobe Projection on right occipital lobe FIGURE 2.33 RETINOGENICULOSTRIATE VISUAL PATHWAY• The retina has two types of photoreceptors: cones that mediate color vision and rods that mediate light perception but with low acuity. The greatest acuity is found in the region of the macula of the retina, where only

cones are found (upper left panel). Visual signals are conveyed by the ganglion cells whose axons course in the optic nerves. Visual signals from the nasal retina cross in the 84 optic chiasm while information from the temporal retina remains in the ipsilateral optic tract. Fibers synapse in the lateral geniculate nucleus (visual field is topographically represented here and inverted), and signals are conveyed to the visual cortex on the medial surface of the occipital lobe. NEUROPHYSIOLOGY Auditory System: Cochlea Cochlear nerve A. Membranous labyrinth within bony labyrinth (path of sound waves) Semicircular canals Utricle Saccule Scala vestibuli Cochlear duct (scala media) Scala tympani B. Section through turn of cochlea Round window Scala vestibuli (perilymph); weakly +80 mV positive Efferent nerve fibers Oval window and stapes Vestibular (Reissner’s) membrane Cochlear duct (scala media; endolymph) Tectorial membrane Spiral ligament Bone Outer hair cells; ⫺60 mV

Scala tympani (perilymph); 0 mV Afferent nerve fibers Basilar membrane Spiral ganglion C. Spiral organ of Corti Inner hair cell; ⫺60 mV Hair cells Inner Outer Tectorial membrane Stereocilia Rods and tunnel of Corti Basilar membrane Supporting cells Afferent nerve fibers Spiral lamina Spiral ganglion Efferent nerve fibers As basilar membrane moves up, hairs are deflected outward, causing depolarization of hair cells and increased firing of afferent nerve fibers FIGURE 2.34 COCHLEAR RECEPTORS• The cochlea transduces sound into electrical signals. This is accomplished by the hair cells, which depolarize in response to vibration of the basilar membrane. The basilar membrane moves in response to pressure changes imparted on the oval window of the cochlea in response to vibrations of the tympanic membrane. 85 NEUROPHYSIOLOGY Auditory System: Pathways Acoustic area of temporal lobe cortex Medial geniculate body Brachium of inferior colliculus Inferior colliculus

Midbrain Lateral lemnisci Nuclei of lateral lemnisci Medulla oblongata Correspondence between cochlea and acoustic area of cortex: Low tones Middle tones High tones Dorsal cochlear nucleus Inferior cerebellar peduncle Ventral cochlear nucleus Cochlear division of vestibulocochlear nerve Dorsal acoustic stria Reticular formation Trapezoid body Intermediate acoustic stria Superior olivary complex Inner Outer Spiral ganglion Hair cells FIGURE 2.35 AUDITORY PATHWAYS• The cochlea transduces sound into electrical signals. Axons convey these signals to the dorsal and ventral cochlear nuclei, where it is tonotopically organized. Following a series of integrated relay pathways, the ascending pathway projects to the thalamus (medial 86 geniculate bodies) and then the acoustic cortex in the transverse gyrus of the temporal lobe, where information is tonotopically represented (low, middle, and high tones). NEUROPHYSIOLOGY Vestibular System: Receptors A. Membranous labyrinth

Vestibular ganglion Superior semicircular canal Vestibular and cochlear divisions of vestibulocochlear n. Maculae Saccule Utricle Cristae within ampullae Horizontal semicircular canal Posterior semicircular canal Cochlear duct (scala media) B. Section of crista Opposite wall of ampulla Gelatinous cupula Hair tufts C. Section of macula Otoconia Gelatinous otolithic membrane Hair tuft Hair cells Supporting cells Basement membrane Nerve fibers Hair cells Nerve fibers Basement membrane Excitation D. Structure and innervation of hair cells Inhibition Kinocilium Kinocilium Stereocilia Basal body Cuticle Cuticle Stereocilia Basal body Hair cell (type I) Hair cell (type II) Supporting cells Supporting cell Afferent nerve calyx Efferent nerve endings Efferent nerve ending Afferent nerve endings Basement membrane Myelin sheath Myelin sheath FIGURE 2.36 VESTIBULAR RECEPTORS• The vestibular apparatus detects movement of the head in the form of linear and angular

acceleration. This information is important for the control of eye movements so that the retina can be provided with a stable visual image. It is also important for the control of posture. The utricle and saccule respond to linear acceleration, such as the pull of gravity. The three semicircular canals are aligned so that the angular movement of the head can be sensed in all planes. The sensory hair cells are located in the maculae of the utricle and saccule and in the cristae within each ampullae. 87 NEUROPHYSIOLOGY Vestibular System: Vestibulospinal Tracts Excitatory endings Inhibitory endings Superior Medial Lateral Inferior Ascending fibers in medial longitudinal fasciculi Vestibular nuclei Rostral Upper limb Trunk Ventral Dorsal To cerebellum Lower limb Caudal Somatotopical pattern in lateral vestibular nucleus Vestibular ganglion and nerve Motor neuron (controlling neck muscles) Medial vestibulospinal fibers in medial longitudinal fasciculi Lateral

vestibulospinal tract Excitatory interneuron Excitatory endings to back muscles ? Inhibitory interneuron ? Lower part of cervical spinal cord Fibers from maculae (gravitational stimuli) To flexor muscles To extensor muscles ? To axial muscles Fibers from cristae (rotational stimuli) Inhibitory ending ? To axial muscles Inhibitory ending Lumbar part of spinal cord Excitatory ending Lateral vestibulospinal tract Inhibitory interneuron Excitatory synapse To flexor muscles To extensor muscles FIGURE 2.37 VESTIBULOSPINAL TRACTS• Sensory input from the vestibular apparatus is used to maintain stability of the head and to maintain balance and posture. Axons convey vestibular information to the vestibular nuclei in the pons, and then secondary axons distribute this information to five sites: spinal 88 cord (muscle control), cerebellum (vermis), reticular formation (vomiting center), extraocular muscles, and cortex (conscious perception). This figure shows only the

spinal cord pathways NEUROPHYSIOLOGY Gustatory (Taste) System: Receptors A. Tongue Foliate papillae B. Section through vallate papilla Taste buds Duct of gustatory (Ebner’s) gland C. Taste bud Epithelium Fungiform papillae Vallate papillae Basement membrane Nerve plexus Microvilli Taste pore Nerve fibers emerging from taste buds Taste cells Desmosomes Epithelium Large nerve fiber Basement membrane Fibroblast Granules Small nerve fiber Schwann cell Intercellular space Large nerve fiber Collagen Microvilli D. Detail of taste pore E. Detail of base of receptor cells FIGURE 2.38 TASTE RECEPTORS• Taste buds on the tongue respond to various chemical stimuli. Taste cells, like neurons, normally have a net negative charge internally and are depolarized by stimuli, thus releasing transmitters that depo- larize neurons connected to the taste cells. A single taste bud can respond to more than one stimulus. The four traditional taste qualities that are sensed are sweet,

salty, sour, and bitter. 89 NEUROPHYSIOLOGY Gustatory (Taste) System: Pathways Ventral posteromedial (VPM) nucleus of thalamus Sensory cortex (just below face area) Lateral hypothalamic area Amygdala Mesencephalic nucleus and Motor nucleus of trigeminal n. Pontine taste area Trigeminal (V) n. Maxillary n. Mandibular n. Pons Pterygopalatine ganglion Greater petrosal n. Geniculate ganglion Facial (VII) n. and Nervus inermedius Rostral part of nucleus of solitary tract Otic ganglion Lingual n. Chorda tympani Glossopharyngeal (IX) n. Fungiform papillae Foliate papillae Lower part of medulla oblongata Valiate papillae Petrosal (inferior) ganglion of glossopharyngeal n. Nodose (inferior) ganglion of vagus n. Vagus (X) n. Epiglottis Larynx Superior laryngeal n. 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 NEUROPHYSIOLOGY

Olfactory System: Receptors Olfactory bulb Lateral nasal wall A. Distribution of olfactory epithelium (blue area) Cribriform plate of ethmoid bone Septum B. Schema of section through olfactory mucosa Cribriform plate Schwann cell Olfactory gland Unmyelinated olfactory axons Basement membrane Sustentacular cells Endoplasmic reticulum Nucleus Olfactory cells Dendrites Terminal bars (desmosomes) Olfactory rod (vesicle) Villi Cilia Mucus FIGURE 2.40 OLFACTORY RECEPTORS• The sensory cells that make up the olfactory epithelium respond to odorants by depolarizing. Like taste buds, an olfactory cell can respond to more than one odorant. There are six general odor qualities that can be sensed: floral, ethereal (e.g, pears), musky, camphor (e.g, eucalyptus), putrid, and pungent (eg, vinegar, peppermint) 91 NEUROPHYSIOLOGY Olfactory System: Pathway Efferent fibers Afferent fibers Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process

Fibers from contralateral olfactory bulb Fibers to contralateral olfactory bulb Anterior commissure Tufted cell Medial olfactory stria Periglomerular cell Olfactory trigone and olfactory tubercle Glomerulus Olfactory nerve fibers Anterior perforated substance Lateral olfactory stria Lateral olfactory tract nucleus Piriform lobe Uncus Amygdala (in phantom) Entorhinal area Olfactory epithelium Olfactory nerves Olfactory bulb Olfactory tract Anterior olfactory nucleus Cribriform plate of ethmoid bone FIGURE 2.41 OLFACTORY PATHWAY• Olfactory stimuli are detected by the nerve fibers of the olfactory epithelium and conveyed to the olfactory bulb (detailed local circuitry shown in upper left panel). Integrated signals pass along the olfactory tract and centrally diverge to pass to the anterior commis- 92 sure (some efferent projections course to the contralateral olfactory bulb, blue lines) or terminate in the ipsilateral olfactory trigone (olfactory tubercle). Axons then

project to the primary olfactory cortex (piriform cortex), entorhinal cortex, and amygdala. 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 InstallAcrobatexe 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 50 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 CDROM drive) 4. Under Files of Type, click All Files 5. Double-click the Neuro Atlaspdf

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