neurology atlas

Atlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations Illustrations by Frank H. Netter, MD John A. Craig, MD James Perkins, MS, MFA Text by John T. Hansen, PhD Bruce M. Koeppen, MD, PhDAtlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations Copyright ©2002 Icon Custom Communications. All rights reserved. The contents of this book may not be reproduced in any form without written authorization from Icon Custom Communications. Requests for permission should be addressed to Permissions Department, Icon Custom Communications, 295 North St., Teterboro NJ 07608, or can be made at www. Netterart.com. NOTICE Every effort has been taken to confirm the accuracy of the information presented. Neither the publisher nor the authors can be held responsible for errors or for any consequences arising from the use of the information contained herein, and make no warranty, expressed or implied, with respect to the contents of the publication. Printed in U.S.A.Foreword Frank Netter: The Physician, The Artist, The Art This selection of the art of Dr. Frank H. Netter on neuroanatomy and neurophysiology is drawn from the Atlas of Human Anatomy and Netter’s Atlas of Human Physiology. Viewing these pictures again prompts reflection on Dr. Netter’s work and his roles as physician and artist. Frank H. Netter was born in 1906 in New York City. He pursued his artistic muse at the Sorbonne, the Art Student’s League, and the National Academy of Design before entering medical school at New York University, where he received his M.D. degree in 1931. During his student years, Dr. Netter’s notebook sketches attracted the attention of the medical faculty and other physicians, allowiin 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 qualitiie is to miss the real strength and intent of the art. This intellectual process requires thorough understanndin of the topic, as Dr. Netter wrote: “Strange as it may seem, the hardest part of making a medicca 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 anatommy In pursuit of this principle Dr. Netter often integrates pertinent basic and clinical science elemeent 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 shrivelle tissues and organs. Netter the physician chose to render “live” versions of these structures—not shriveled, colorless, formaldehyde-soaked tissues, but plump, robust organs, glowing with color! The value of Dr. Netter’s approach is clearly demonstrated by the plates in this selection. John A. Craig, MD Austin, TexasThis 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 monograaph 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 commissioone this special edition of Netter’s work, which includes his beautiful and instructive illustrations of nervous system anatomy as well as his depictions of neurophysiological concepts and functions. We hope that readers will find Dr. Netter’s renderings of neurological form and function interesting and useful.Part 1 Neuroanatomy Cerebrum—Medial Views . . . . . . . . . . . . . . . . . 2 Cerebrum—Inferior View. . . . . . . . . . . . . . . . . . 3 Basal Nuclei (Ganglia). . . . . . . . . . . . . . . . . . . . 4 Thalamus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Cerebellum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Brainstem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Fourth Ventricle and Cerebellum . . . . . . . . . . . 8 Accessory Nerve (XI) . . . . . . . . . . . . . . . . . . . . 9 Arteries to Brain and Meninges . . . . . . . . . . . 10 Arteries to Brain: Schema . . . . . . . . . . . . . . . . 11 Arteries of Brain: Inferior Views . . . . . . . . . . . 12 Cerebral Arterial Circle (Willis) . . . . . . . . . . . 13 Arteries of Brain: Frontal View and Section . . 14 Arteries of Brain: Lateral and Medial Views. . . . . . . . . . . . . . . 15 Arteries of Posterior Cranial Fossa . . . . . . . . . 16 Veins of Posterior Cranial Fossa . . . . . . . . . . . 17 Deep Veins of Brain. . . . . . . . . . . . . . . . . . . . . 18 Subependymal Veins of Brain . . . . . . . . . . . . . 19 Hypothalamus and Hypophysis . . . . . . . . . . . 20 Arteries and Veins of Hypothalamus and Hypophysis . . . . . . . . 21 Relation of Spinal Nerve Roots to Vertebrae . . . 22 Autonomic Nervous System: General Topography. . . . . . . . . . . . . . . . . . . 23 Spinal Nerve Origin: Cross Sections. . . . . . . . 24 Olfactory Nerve (I): Schema . . . . . . . . . . . . . . 25 Optic Nerve (II) (Visual Pathway): Schema . . . . . . . . . . . . . . 26 Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves: Schema. . . . . . . 27 Trigeminal Nerve (V): Schema . . . . . . . . . . . . 28 Facial Nerve (VII): Schema . . . . . . . . . . . . . . . 29 Vestibulocochlear Nerve (VIII): Schema. . . . . 30 Glossopharyngeal Nerve (IX): Schema . . . . . . 31 Vagus Nerve (X): Schema . . . . . . . . . . . . . . . . 32 Accessory Nerve (XI): Schema . . . . . . . . . . . . 33 Hypoglossal Nerve (XII): Schema . . . . . . . . . . 34 Nerves of Heart . . . . . . . . . . . . . . . . . . . . . . . . 35 Autonomic Nerves and Ganglia of Abdomen. . . . . . . . . . . . . . . 36 Nerves of Stomach and Duodenum . . . . . . . . 37 Nerves of Stomach and Duodenum (continued) . . . . . . . . . . . . 38 Nerves of Small Intestine . . . . . . . . . . . . . . . . 39 Nerves of Large Intestine . . . . . . . . . . . . . . . . 40 Nerves of Kidneys, Ureters and Urinary Bladder . . . . . . . . . . . . 41 Nerves of Pelvic Viscera: Male . . . . . . . . . . . . 42 Nerves of Pelvic Viscera: Female . . . . . . . . . . 43 Median Nerve . . . . . . . . . . . . . . . . . . . . . . . . . 44 Ulnar Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Radial Nerve in Arm and Nerves of Posterior Shoulder . . . . . . . . 46 Radial Nerve in Forearm . . . . . . . . . . . . . . . . . 47 Sciatic Nerve and Posterior Cutaneous Nerve of Thigh . . . . . . . . . . . . . . 48 Tibial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Common Fibular (Peroneal) Nerve. . . . . . . . . 50 Click any title below to link to that plate.2NEUROANATOMY Cerebrum: Medial Views Cingulate gyrus Cingulate sulcus Medial frontal gyrus Sulcus of corpus callosum Fornix Septum pellucidum Central sulcus (Rolando) Sagittal section of brain in situ Interventricular foramen (Monro) Interthalamic adhesion Thalamus and 3rd ventricle Subcallosal (parolfactory) area Anterior commissure Subcallosal gyrus Hypothalamic sulcus Lamina terminalis Supraoppti recess Paracentral sulcus Paracentral lobule Corpus callosum Precuneus Superior sagittal sinus Choroid plexus of 3rd ventricle Stria medullaris of thalamus Parietooccipital sulcus Habenular commissure Cuneus Pineal body Posterior commissure Calcarine sulcus Straight sinus in tentorium cerebelli Great cerebral vein (Galen) Superior colliculus Inferior colliculus Tectal (quadrigeminal) plate Cerebellum Superior medullary velum 4th ventricle and choroid plexus Inferior medullary velum Medulla oblongata Hypophysis (pituitary gland) Mammillary body Cerebral peduncle Pons Cerebral aqueduct (Sylvius) Genu Rostrum Trunk Splenium of corpus callosum Isthmus of cingulate gyrus Parietooccipital sulcus Cuneus Calcarine sulcus Lingual gyrus Crus Body Column of fornix Fimbria of hippocampus Dentate gyrus Parahippocampal gyrus Lateral occipitotemporal gyrus Occipitotemporal sulcus Medial occipitotemporal gyrus Rhinal sulcus Collateral sulcus Olfactory tract Optic nerve (II) Uncus Mammillary body Mammillothalamic fasciculus Cingulate gyrus Medial surface of cerebral hemisphere: brainstem excised Tuber cinereum Optic chiasm Marginal sulcus3 NEUROANATOMY Cerebrum: Inferior View Sectioned brainstem Frontal pole of cerebrum Straight gyrus Olfactory sulcus Orbital sulci Orbital gyri Temporal pole Lateral sulcus (Sylvius) Inferior temporal sulcus Inferior temporal gyrus Rhinal sulcus Uncus Collateral sulcus Parahippocampal gyrus Medial occipitotemporal gyrus Calcarine sulcus Isthmus of cingulate gyrus Longitudinal cerebral fissure Occipital pole of cerebrum Apex of cuneus Splenium of corpus callosum Cerebral aqueduct Pulvinar of thalamus Red nucleus Substantia nigra Cerebral crus Mammillary body Tuber cinereum Optic tract Optic nerve (II) (cut) Optic chiasm Longitudinal cerebral fissure Genu of corpus callosum Lamina terminalis Olfactory bulb Olfactory tract Posterior perforated substance (in interpeduncular fossa) Inferior (inferolateeral margin of cerebrum Hypophysis (pituitary gland) Anterior perforated substance Superior colliculus (of corpora quadrigemina) Medial geniculate body Lateral geniculate body Inferior temporal gyrus Occipitotemporal sulcus Lateral occipitotemppora gyrus4NEUROANATOMY Basal Nuclei (Ganglia) Horizontal sections through cerebrum Genu of corpus callosum Lateral ventricle Septum pellucidum Column of fornix Insula (island of Reil) Interthalamic adhesion Thalamus Crus of fornix Choroid plexus of lateral ventricle Splenium of corpus callosum Head of caudate nucleus Anterior limb Genu Posterior limb Putamen Globus pallidus 3rd ventricle External capsule Claustrum Retrolenticular part of internal capsule Tail of caudate nucleus Hippocampus and fimbria Occipital (posterior) horn of lateral ventricle Habenula Pineal body Cleft for internal capsule Organization of basal nuclei (ganglia) Caudate nucleus Putamen Globus pallidus Striatum Lentiform nucleus Corpus striatum Basal nuclei (ganglia) Caudate nucleus Levels of sections above Body Head Lentiform nucleus (globus pallidus medial to putamen) Thalamus Pulvinar Medial geniculate body Lateral geniculate body Tail of caudate nucleus Amygdaloid body A Interrelationship of thalamus, lentiform nucleus, caudate nucleus and amygdaloid body (schema): left lateral view B A B A B of internal capsule Lentiform nucleus AB5 NEUROANATOMY ThalamusInterventricular foramen (Monro) 3rd ventricle Corpus callosum (cut) Head of caudate nucleus Septum pellucidum Columns of fornix Anterior tubercle Stria terminalis Interthalamic adhesion Lamina affixa Stria medullaris Habenular trigone Pulvinar (retracted) Lateral geniculate body Medial geniculate body Brachium of superior colliculus Brachium of inferior colliculus Choroid plexus Superior thalamostriate vein Pes hippocampi Internal cerebral vein Dentate gyrus Collateral eminence Hippocampus Fimbria of hippocampus Posterior commissure Habenular commissure Pineal body Collateral trigone Calcar avis Tela choroidea (cut edge) of 3rd ventricle Temporal (inferior) horn of lateral ventricle Occipital (posterior) horn of lateral ventricleCalcarine sulcus Superior colliculus Inferior colliculus Cerebellum Pulvinar Reticular nucleus Median nuclei 3rd ventricle Pulvinar Lateral geniculate body Medial geniculate body 3rd ventricle Interthalamic adhesion Intralaminar nuclei External medullary lamina Internal medullary lamina Schematic section through thalamus (at level of broken line shown in figure at right) Thalamic nuclei CM Centromedian LD Lateral dorsal LP Lateral posterior M Medial MD Medial dorsal VA Ventral anterior VI Ventral intermedial VL Ventral lateral VP Ventral posterior VPL Ventral posterolateral VPM Ventral posteromedial Lateral nuclei Medial nuclei Anterior nuclei Schematic representation of thalamus (external medullary lamina and reticular nuclei removed) MD M CM VPL VPM LP LP LD VP VPL VPM VI VL VA Median Medial lamina medullar y Internal Anterior Lamina6NEUROANATOMY Cerebellum Anterior cerebellar notch Central lobule (II & III) Culmen (IV & V) Declive (VI) Folium (VII A) Superior vermis Posterior cerebellar notch Superior surface Superior vermis Inferior surface Central lobule Lingula (I) Superior medullary velum Flocculus (H X) 4th ventricle Inferior medullary velum Nodule (X) Uvula (IX) Pyramid (VIII) Tuber (VII B) Posterior cerebellar notch Inferior vermis 4th ventricle Superior medullary velum Fastigial Globose Dentate Emboliform Decussation of superior cerebellar peduncles Cerebellar nuclei Section in plane of superior cerebellar peduncle Cerebral crus Medial longitudinal fasciculus Lingula (I) Vermis Nuclear layer of medulla oblongata Superior cerebellar peduncle Secondary (postpyramidal) fissure Posterolateral (dorsolateral) fissure Flocculonodular lobe Posterior lobe Retrotonsillar fissure Tonsil Biventer lobule (H VIII) Horizontal fissure Inferior semilunar (caudal) lobule (H VII B) Anterior lobe Wing of central lobule Superior Middle Inferior Cerebellar peduncles Anterior lobe Quadrangular lobule (H IV-V) Primary fissure Horizontal fissure Simple lobule (H VI) Posterior lobe Postlunate fissure Horizontal fissure Superior semilunar (anseriform) lobule (H VII A) Inferior semilunar (caudal) lobule (H VII B)7 NEUROANATOMY BrainstemPulvinars of thalami Posterolateral view Pineal body Superior colliculi Inferior colliculi Trochlear nerve (IV) Superior medullary velum Superior cerebellar peduncle Cuneate tubercle Gracile tubercle Cuneate fasciculus Gracile fasciculus Rhomboid fossa of 4th ventricle Glossopharyngeal (IX) and vagus (X) nerves Dorsal roots of 1st spinal nerve (C1) Anterior view Optic chiasm Optic tract Tuber cinereum Cerebral crus Lateral geniculate body PonsOlive Pyramid Ventral roots of 1st spinal nerve (C1) Decussation of pyramids Middle cerebellar peduncle Posterior perforated substance Olfactory tract Anterior perforated substance Infundibulum (pituitary stalk) Mammillary bodies Temporal lobe (cut surface) Oculomotor nerve (III) Trochlear nerve (IV) Trigeminal nerve (V) Abducent nerve (VI) Vestibulocochlear nerve (VIII) Flocculus of cerebellum Glossopharyngeal nerve (IX) Vagus nerve (X) Hypoglossal nerve (XII) Accessory nerve (XI) Facial nerve (VII) and intermediate nerve Choroid plexus of 4th ventricle Thalamus (cut surface) Lateral geniculate body Optic tract Medial geniculate body Brachia of superior and inferior colliculi Cerebral crus Pons Trigeminal nerve (V) Middle cerebellar peduncle Vestibulocochlear nerve (VIII) Facial nerve (VII) Inferior cerebellar peduncle Hypoglossal nerve (XII) Accessory nerve (XI)8NEUROANATOMY Fourth Ventricle and Cerebellum Posterior view 3rd ventricle Pulvinar of thalamus Pineal body Superior colliculus Inferior colliculus Trochlear nerve (IV) Superior medullary velum Cerebellar peduncles Lateral recess Superior fovea Sulcus limitans Inferior fovea Trigeminal tubercle Hypoglossal trigone Vagal trigone Obex Gracile fasciculus Interthalamic adhesion Posterior commissure Habenular commissure Pineal body Splenium of corpus callosum Great cerebral vein (Galen) Cuneate fasciculus Lateral funiculus Dorsal median sulcus Gracile tubercle Habenular trigone Geniculate bodies Dorsal median sulcus Superior cerebellar peduncle Locus ceruleus Medial eminence Facial colliculus Vestibular area Striae medullares Tenia of 4th ventricle Cuneate tubercle Superior Middle Inferior Medial Lateral Dentate nucleus of cerebellum Lingula (I) Central lobule (II-III) Culmen (IV-V) Declive (VI) Folium (VII A) Tuber (VII B) Pyramid (VIII) Uvula (IX) Nodulus (X) Choroid plexus of 4th ventricle Tonsil of cerebellum Central canal of spinal cord Medulla oblongata Choroid plexus of 4th ventricle 4th ventricle Medial longitudinal fasciculus Pons Inferior colliculus Tectal (quadrigeminal) plate Superior colliculus Cerebral aqueduct (Sylvius) Cerebral peduncle Hypothalamic sulcus Lamina terminalis Anterior commissure Body of fornix Decussation of pyramids Median aperture (foramen of Magendie) Superior medullary velum Inferior medullary velum Vermis of cerebellum Vermis of cerebellum Interventricular foramen (Monro) Thalamus (in 3rd ventricle) Median sagittal section9 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.10 NEUROANATOMY Arteries to Brain and Meninges Left middle meningeal artery Posterior cerebral artery Superior cerebellar artery Basilar artery Left labyrinthine (internal acoustic) artery Mastoid branch of left occipital artery Anterior inferior cerebellar artery Posterior inferior cerebellar artery Posterior meningeal branch of left ascending pharyngeal artery Left and right vertebral arteries (intracranial part) Posterior meningeal branch of vertebral artery Anterior meningeal branch of vertebral artery Posterior auricular artery Occipital artery 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 Middle cerebral artery Anterior cerebral artery Anterior communicating artery Ophthalmic artery Posterior communicating artery Cavernous sinus Middle meningeal artery Maxillary artery Superficial temporal artery External carotid artery Facial artery Lingual artery Ascending pharyngeal artery Superior laryngeal artery Superior thyroid artery Common carotid artery Ascending cervical artery (cut) Inferior thyroid artery Thyrocervical trunk Brachiocephalic trunk Internal thoracic artery11 NEUROANATOMY Arteries to Brain: Schema Ophthalmic artery Supraorbital artery Supratrochlear artery Lacrimal artery Dorsal nasal artery Middle meningeal artery Angular artery Superficial temporal artery Posterior auricular artery Facial artery Occipital artery Lingual artery Ascending pharyngeal artery Anterior spinal artery Spinal segmental medullary branches Vertebral artery Common carotid artery Deep cervical artery Transverse cervical artery Subclavian artery Internal thoracic artery Suprascapular artery Supreme intercostal artery Costocervical trunk Anterior communicating artery Anastomoses 1 Right–Left 2 Carotid–Vertebral 3 Internal carotid–External carotid 4 Subclavian–Carotid 5 Subclavian–Vertebral Vertebral artery Ascending cervical artery Inferior thyroid artery Thyrocervical trunk Subclavian artery Brachiocephalic trunk Aorta Arch Descending Ascending Middle meningeal artery Anterior tympanic artery Superior cerebellar artery Posterior cerebral artery Middle cerebral artery Posterior communicating artery Anterior cerebral artery Maxillary artery Basilar artery External carotid artery Internal carotid artery Superior thyroid artery Common carotid artery Anterior inferior cerebellar artery Posterior inferior cerebellar artery 5 55 5 5 55 4 43 3 3 3 11 2 5 1 1 Caroticotympanic branch of internal carotid artery12 NEUROANATOMY Arteries of Brain: Inferior Views Medial frontobasal (orbitofrontal) artery Anterior communicating artery Anterior cerebral artery Distal medial striate artery (recurrent artery of Heubner) Internal carotid artery Anterolateral central (lenticulostriate) arteries Middle cerebral artery Lateral frontobasal (orbitofrontal) artery Prefrontal artery Anterior choroidal artery Posterior communicating artery Posterior cerebral artery Superior cerebellar artery Basilar artery Pontine arteries Labyrinthine (internal acoustic) artery Anterior inferior cerebellar artery Vertebral artery Anterior spinal artery Posterior inferior cerebellar artery (PICA) (cut) Posterior spinal artery Cerebral arterial circle (Willis) (broken line) Anterior communicating artery Distal medial striate artery (recurrent artery of Heubner) 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 ventricle13 NEUROANATOMY Cerebral Arterial Circle (Willis) Vessels dissected out: inferior view Anterior cerebral artery (A2 segment) Anterior communicating artery Anterior cerebral artery (A1 segment) Ophthalmic artery Internal carotid artery Middle cerebral artery Posterior communicating artery Posterior cerebral artery (P2 segment) (P1 segment) Superior cerebellar artery Basilar artery Pontine arteries Anterior inferior cerebellar artery Anteromedial central (perforating) arteriesHypothalamic artery Distal medial striate artery (recurrent artery of Heubner) Anterolateral central (lenticulostriate) arteries Superior hypophyseal artery Inferior hypophyseal artery Anterior choroidal 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 Internal carotid artery Superior hypophyseal artery Middle cerebral artery Inferior hypophyseal artery Posterior communicating artery Efferent hypophyseal veins Posterior cerebral artery Anterior communicating artery Optic chiasm Cavernous sinus Infundibulum (pituitary stalk) and long hypophyseal portal veins Adenohypophysis (anterior lobe of pituitary gland) Neurohypophysis (posterior lobe of pituitary gland) Posteromedial central (perforating) arteries Superior cerebellar artery Basilar artery14 NEUROANATOMY Arteries of Brain: Frontal View and Section Corpus callosum Prefrontal artery Anterolateral central (lenticulostriate) arteries Lateral frontobasal (orbitofrontal) artery Anterior parietal (postcentral sulcal) artery Precentral (pre-rolandic) and central (rolandic) sulcal arteries Posterior parietal arteryBranch to angular gyrus Anterior communicating artery Temporal branches (anterior, middle and posterior) Middle cerebral artery and branches (deep in lateral cerebral [sylvian] sulcus) Posterior communicating artery Anterior inferior cerebellar artery Posterior spinal artery 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 Paracentral artery Medial frontal branches Pericallosal artery Callosomarginal artery Polar frontal artery Anterior cerebral arteries Medial frontobasal (orbitofrontal) artery Distal medial striate artery (recurrent artery of Heubner) Internal carotid artery Anterior choroidal artery Posterior cerebral artery Superior cerebellar artery Basilar and pontine arteries Labyrinthine (internal acoustic) artery Vertebral artery Posterior inferior cerebellar artery Anterior spinal artery Falx cerebriCallosomarginal 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 chiasm15 NEUROANATOMY Arteries of Brain: Lateral and Medial Views Anterior parietal (postcentral sulcal) artery Central (rolandic) sulcal artery Precentral (pre-rolandic) sulcal artery Prefrontal sulcal artery Terminal branches of anterior cerebral artery Lateral frontobasal (orbitofrontal) artery Left middle cerebral artery Left anterior cerebral artery Anterior communicating artery Right anterior cerebral artery Left internal carotid artery Pericallosal artery Posterior Intermediate Anterior Medial frontal branches Callosomarginal artery Polar frontal artery Right anterior cerebral artery Medial frontobaasa (orbitofronntal artery Anterior communicating artery (cut) Distal medial striate artery (recurrent artery of Heubner) Right internal carotid artery Posterior parietal artery Branch to angular gyrus Terminal branches of posterior cerebral artery Posterior temporal branch Middle temporal branch Superior and inferior terminal branches (trunks) Anterior temporal branch Paracentral artery Cingular branches Right posterior cerebral artery Precuneal artery Dorsal branch to corpus callosum Parietooccipital branch Calcarine branch Posterior temporal branch Anterior temporal branch Posterior communicating artery Polar temporal artery Medial occipital artery Occipitotemporal branches Note: Anterior parietal (postcentral sulcal) artery also occurs as separate anterior parietal and postcentral sulcal arteries16 NEUROANATOMY Arteries of Posterior Cranial Fossa Thalamogeniculate arteries Anterior choroidal artery Crura of fornix Anterolateral central (lenticulostriate) arteries Heads of caudate nuclei Septum pellucidum Corpus callosum Anterior cerebral arteries Longitudinal cerebral fissure Lateral and medial geniculate bodies of left thalamus Choroid plexuses of lateral ventricles Pulvinars of left and right thalami Splenium of corpus callosum Occipital (posterior) horn of right lateral ventricle Right dorsal branch to corpus callosum (posterior pericallosal artery) Parietooccipital Calcarine Branches of right posterior cerebral artery Optic nerve (II) Ophthalmic artery Thalamoperforating arteries Anterior cerebral artery Middle cerebral artery Posterior communicating artery Left internal carotid artery Basilar artery Pontine arteries Labyrinthine (internal acoustic) artery Posterior cerebral artery Superior cerebellar artery Anterior meningeal branch of vertebral artery Anterior inferior cerebellar artery Temporal branches of posterior cerebral artery Anterior spinal artery Superior colliculi Posterior medial choroidal artery to choroid plexus of 3rd ventricle Posterior lateral choroidal artery Lateral (marginal) branch Inferior vermian artery (phantom) Choroidal branch to 4th ventricle (phantom) and Cerebellar tonsillar branch of posterior inferior cerebellar artery Outline of 4th ventricle (broken line) Posterior meningeal branch of vertebral artery Posterior inferior cerebellar artery (PICA) Left posterior spinal artery Left vertebral artery III IV V VIII VII VI IXX XI Superior vermian branch17 NEUROANATOMY Veins of Posterior Cranial Fossa Parts of cerebellum L Lingula TU Tuber CL Central lobule P Pyramid C Culmen U Uvula D Declive N Nodule F Folium T Tonsil Left superior and inferior colliculi Basal vein (Rosenthal) Posterior mesencephalic vein Medial geniculate body Lateral geniculate body Optic tract Left thalamus (cut surface) Inferior thalamostrriat veins Optic nerve (II) Lateral mesencephalic vein Deep middle cerebral vein (cut) Anterior cerebral vein Anterior pontomesenccephali vein Petrosal vein (draining to superior petrosal sinus) Superior, middle and inferior cerebellar peduncles Trigeminal nerve (V) Transverse pontine vein Lateral pontine vein Anteromedian medullary vein Vein of lateral recess of 4th ventricle Anterior spinal vein 4th ventricle Confluence of sinuses Left transverse sinus (cut) Superior sagittal sinus Left pulvinar Right pulvinar Internal cerebral veins Dorsal vein of corpus callosum Inferior sagittal sinus Straight sinus Falx cerebri Splenium of corpus callosum Great cerebral vein (Galen) Tentorium cerebelli (cut) C C D FTU P U T CL L N Superior vermian vein Inferior vermian vein Falx cerebelli (cut) and occipital sinus Inferior cerebellar hemispheric veins Posterior spinal vein Precentral cerebellar vein Preculminate vein Intraculminate vein Superior cerebellar vein (inconstant) (Inferior retrotonsillar) vein of cerebellomedullary cistern Superior retrotonsillar vein18 NEUROANATOMY Deep Veins of Brain Longitudinal cerebral fissure Anterior cerebral veins 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 Rostrum of corpus callosum 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 Dissection: inferior view Uncal vein Optic chiasm Inferior cerebral veins Inferior anastomotic vein (Labbé) Anterior cerebral vein Deep middle cerebral vein Cerebral crus Basal vein (Rosenthal) Lateral geniculate body Medial geniculate body Pulvinar of thalamus Splenium of corpus callosum Great cerebral vein (Galen) Superficial middle cerebral vein (draining to sphenoparietal sinus)19 NEUROANATOMY Subependymal Veins of Brain Lateral direct vein Superior thalamic veins Posterior veins of septum pellucidum Superior choroid vein Transverse veins of caudate nucleus Superior thalamostriate vein Lateral ventricle Anterior vein of caudate nucleus Anterior vein of septum pellucidum Genu of corpus callosum Interventricular foramen (Monro) Anterior commissure Interthalamic adhesion Anterior cerebral vein Optic chiasm 3rd ventricle Deep middle cerebral vein Inferior thalamostriate veins Basal vein (Rosenthal) Temporal (inferior) horn of lateral ventricle Posterior mesencephalic vein Hippocampal and inferior ventricular veins Cerebral aqueduct 4th ventricle Lateral and median apertures of 4th ventricle Veins on lateral wall of ventricle Veins on medial wall and floor of ventricle All other veins Cerebellum Posterior terminal vein of caudate nucleus (posterior part of thalamostriate vein) Internal cerebral veins (right and left) Medial (atrial) vein of lateral ventricle Lateral (atrial) vein of lateral ventricle Splenium of corpus callosum Great cerebral vein (Galen) Dorsal vein of corpus callosum Inferior sagittal sinus Internal occipital vein Straight sinus Occipital (posterior) horn of lateral ventricle Superior vermian vein20 NEUROANATOMY Hypothalamus and Hypophysis Septum pellucidum Thalamus Fornix Hypothalamic sulcus Anterior commissure Paraventricular Posterior Dorsomedial Supraoptic Ventromedial Arcuate (infundibular) Mammillary Principal nuclei of hypothalamus Optic chiasm Infundibulum (pituitary stalk) Hypophysis (pituitary gland) Mammillothalamic tract Dorsal longitudinal fasciculus and other descending pathways Lamina terminalis Paraventricular hypothalamic nucleus Supraoptic hypothalamic nucleus Supraopticohypophyseal tract Tuberohypophyseal tract Hypothalamohypophyseal tract Infundibulum (pituitary stalk) Fibrous trabecula Pars intermedia Pars distalis Cleft Pars tuberalis Adenohypophysis (anterior lobe of pituitary gland) Hypothalamic sulcus Mammillary body Arcuate (infundibular) nucleus Median eminence of tuber cinereum Infundibular stem Infundibular process Neurohypophysis (posterior lobe of pituitary gland)21 NEUROANATOMY Arteries and Veins of Hypothalamus and Hypophysis Primary plexus of hypophyseal portal system Efferent hypophyseal vein to cavernous sinus Capillary plexus of infundibular process Efferent hypophyseal vein to cavernous sinus Long hypophyseal portal veins Artery of trabecula Trabecula (fibrous tissue) Short hypophyseal portal veins Neurohypophysis (posterior lobe of pituitary gland) Superior hypophyseal artery Secondary plexus of hypophyseal portal system Hypothalamic vessels Efferent hypophyseal veins to cavernous sinus Efferent hypophyseal vein to cavernous sinus Adenohypophysis (anterior lobe of pituitary gland) Inferior hypophyseal artery22 NEUROANATOMY Relation of Spinal Nerve Roots to Vertebrae C1 spinal nerve exits above C1 vertebra Cervical enlargement Base of skull C8 spinal nerve exits below C7 vertebra (there are 8 cervical nerves but only 7 cervical vertebrae) 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 Lumbar enlargement Conus medullaris (termination of spinal cord) Internal terminal filum (pial part) External terminal filum (dural part) Termination of dural sac Cauda equina Coccygeal nerve Coccyx Coccygeal nerve Cervical nerves Thoracic nerves Lumbar nerves Sacral and coccygeal nerves Medial protrusion at disc level L4–5 rarely affects L4 spinal nerve but may affect L5 spinal nerve and sometimes S1–4 spinal nerves C1 C2 C3 C4 C5 C6 C7 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L2L3 L5L3 L4 L4 L5 Sacrum S1 S2 S3 S4 S5 S2 L4 L4 L5 L5 S1 L4 L4 L5 L5 S1 S2S3S4 S523 NEUROANATOMY 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 Sympathetic fibers Parasympathetic fibers 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 Prostatic plexus24 NEUROANATOMY Spinal Nerve Origin: Cross Sections Section through thoracic vertebra Fat in epidural space Sympathetic ganglion Ventral root White and gray rami communicantes Spinal nerve Ventral ramus (intercostal nerve) Dorsal ramus Aorta Dura mater Subarachnoid space Arachnoid mater* Pia mater* Recurrent meningeal branches of spinal nerve Pleura Lung Spinal sensory (dorsal root) ganglion Dorsal root Dura mater Arachnoid mater Ventral root Spinal nerve Ventral ramus (contributes to lumbar plexus) Dorsal ramus Spinal sensory (dorsal root) ganglion Dorsal root Conus medullaris *Leptomeninges Dorsal and ventral roots of lumbar and sacral spinal nerves forming cauda equina Gray ramus communicans Fat in epidural space Sympathetic ganglion Section through lumbar vertebra Lateral branch Medial branch of dorsal ramus of spinal nerve Lateral horn of gray matter of spinal cord Body of vertebra Internal vertebral (epidural) venous plexus25 NEUROANATOMY Olfactory Nerve (I): Schema Olfactory bulb cells: schema Efferent fibers to olfactory bulb Afferent fibers from bulb to central connections and contralateral bulb Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process Tufted cell Periglomerular cell Glomerulus Subcallosal (parolfactory) area Olfactory nerve fibers Septal area and nuclei Fibers from Fibers to Contralateral olfactory bulb Anterior commissure Medial olfactory stria Olfactory cells Olfactory mucosa Olfactory nerves (I) Olfactory bulb Cribriform plate of ethmoid bone Anterior olfactory nucleus Olfactory tract Olfactory trigone and olfactory tubercle Lateral olfactory stria Lateral olfactory tract nucleus Anterior perforated substance Amygdaloid body (phantom) Piriform lobe Uncus Hippocampal fimbria Dentate gyrus Parahippocampal gyrus26 NEUROANATOMY Optic Nerve (II) (Visual Pathway): Schema Overlapping visual fields Projection on left retina Choroid Choroid Periphery Macula Projection on right retina Central darker circle represents macular zone Lighter shades represent monocular fields Each quadrant a different color Projection on right dorsal lateral geniculate nucleus Optic nerves (II) Optic chiasm Optic tracts Projection on left dorsal lateral geniculate nucleus Lateral geniculate bodies Optic radiation Optic radiation Calcarine sulcus Calcarine sulcusProjection on left occipital lobe Projection on right occipital lobe Structure of retina: schema A Amacrine cells B Bipolar cells C Cones G Ganglion cells H Horizontal cells P Pigment cells R Rods G G A B H A B H R R C C P P27 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 Sensory root of ciliary ganglion Sympathetic root of ciliary ganglion Superior division of oculomotor nerve Frontal nerve (cut) Lacrimal nerve (cut) Nasociliary nerve Abducent nucleus Trochlear nucleus Oculomotor nucleus Accessory oculomotor (Edinger-Westphal) nucleus (parasympathetic) Trochlear nerve (IV) Oculomotor nerve (III) Ophthalmic nerve (V1) Infraorbital nerve Zygomatic nerve (cut) Inferior oblique muscle Ciliary muscle Dilator muscle of pupil Sphincter muscle of pupil Pterygopalatine ganglion Inferior division of oculomotor nerve Medial rectus muscle Inferior rectus muscle Parasympathetic root of ciliary ganglion Efferent fibers Afferent fibers Sympathetic fibers Parasympathetic fibers Abducent nerve (VI) Mandibular nerve (V3) Maxillary nerve (V2) Internal carotid artery and nerve plexus Lateral rectus muscle and abducent nerve (turned back) Cavernous plexus Common tendinous ring28 NEUROANATOMY Trigeminal Nerve (V): Schema Efferent fibers Afferent fibers Proprioceptive fibers Parasympathetic fibers Sympathetic fibers Ophthalmic nerve (V1) Tentorial (meningeal) branch Nasociliary nerve Lacrimal nerve Frontal nerve Sensory root of ciliary ganglion Ciliary ganglion Posterior ethmoidal nerve Long ciliary nerve Short ciliary nerves Anterior ethmoidal nerve Supraorbital nerve Supratrochlear nerve Infratrochlear nerve Internal nasal branches and External nasal branches of anterior ethmoidal nerve Maxillary nerve (V2) Meningeal branch Zygomaticotemporal nerve Zygomaticofacial nerve Zygomatic nerve Infraorbital nerve Pterygopalatine ganglion Superior alveolar branches of infraorbital nerve Nasal branches (posterior superior lateral, nasopalatine and posterior superior medial) 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 Submandibular ganglion Mylohyoid nerve Mandibular nerve (V3) Inferior alveolar nerve Otic ganglion Tensor tympani nerve Chorda tympani nerve Superficial temporal branches Articular branch and anterior auricular nerves Auriculotemporal nerve Parotid branches Meningeal branch Lesser petrosal nerve (from glossopharyngeal nerve [IX]) Facial nerve (VII) Trigeminal nerve (V) ganglion and nuclei Motor nucleus Mesencephalic nucleus Principal sensory nucleus Spinal tract and nucleus29 NEUROANATOMY Facial Nerve (VII): Schema Greater petrosal nerve Deep petrosal nerve (from internal carotid plexus) Lesser petrosal nerve Nerve (vidian) of pterygoid canal Otic ganglion Pterygopalatine ganglion Facial muscles Orbicularis oculi Frontal belly (frontalis) of occipitofrontalis Corrugator supercilii Zygomaticus major Zygomaticus minor Procerus Nasalis Facial nerve (VII) Levator labii superioris Levator anguli oris Levator labii superioris alaeque nasi Temporal branches Zygomatic Mentalis Depressor septi nasi Orbicularis oris Depressor anguli oris Depressor labii inferioris (Risorius) (not shown) Buccinator Platysma Buccal branches Marginalmandibularbranch anterior 2⁄3 tongue Taste:of Efferent fibers Afferent fibers Parasympathetic fibers Sympathetic fibers Sublingual gland Submandibular gland Submandibular ganglion Lingual nerve (from trigeminal nerve) Chorda tympani nerve Caroticotympanic nerve (from internal carotid plexus) Stylohyoid muscle Digastric muscle (posterior belly) Glossopharyngeal nerve (IX) Tympanic nerve (Jacobson) (from glossopharyngeal nerve) Tympanic plexus Stylomastoid foramen Nerve to stapedius muscle Posterior auricular nerve Branches to auricular muscles Occipital branch of posterior auricular nerve Cervical branch Geniculate ganglion Internal carotid plexus (on internal carotid artery) Internal acoustic meatus Intermediate nerve Motor nucleus of facial nerve Superior salivatory nucleus Solitary tract nucleus Occipital belly (occipitalis) of occipitofrontalis muscle branches30 NEUROANATOMY Vestibulocochlear Nerve (VIII): Schema Afferent fibers Geniculum of facial nerve (site of geniculate ganglion) Facial canal Greater petrosal nerve Cochlear (spiral) ganglion Vestibular nerve Cochlear nerve Tympanic cavity Chorda tympani nerve Motor root of facial nerve and intermediate nerve Vestibulocochlear nerve (VIII) Medulla oblongata (cross section) Internal acoustic meatus Medial Superior Inferior Lateral Vestibular nuclei (diagrammatic) Anterior Posterior Cochlear nuclei Inferior cerebellar peduncle (to cerebellum) Vestibular ganglion Inferior division Superior division Saccule Ampulla of posterior semicircular duct Utricle Ampulla of superior semicircular duct Ampulla of lateral semicircular duct of vestibular nerve Head of malleus Incus31 NEUROANATOMY Glossopharyngeal Nerve (IX): Schema Efferent fibers Afferent fibers Parasympathetic fibers Tympanic nerve (Jacobson) Tympanic cavity and plexus Stylomastoid foramen Caroticotympanic nerve (from internal carotid plexus) Greater petrosal nerve Deep petrosal nerve Nerve (vidian) of pterygoid canal Lesser petrosal nerve Pterygopalatine ganglion Mandibular nerve (V3) Otic ganglion Auriculotemporal nerve Parotid gland Tubal branch of tympanic plexus Pharyngotympanic (auditory) tube and pharyngeal opening Stylopharyngeus muscle (and branch from glossopharyngeal nerve) Spinal tract and spinal nucleus of trigeminal nerve Solitary tract nucleus Nucleus ambiguus Inferior salivatory nucleus Geniculate ganglion of facial nerve Glossopharyngeal nerve (IX) Jugular foramen Communication to auricular branch of vagus nerve Superior and Inferior ganglia of Glossopharyngeal nerve Communication to facial nerve (VII) Vagus nerve (X) Superior cervical sympathetic ganglion Sympathetic trunk Carotid branch of glossopharyngeal nerve Internal carotid artery Carotid sinus Carotid body Common carotid artery External carotid artery Taste and somatic sensation: posterior 1⁄3 of tongue Pharyngeal plexus Pharyngeal, tonsillar and lingual branches of glossopharyngeal nerve Pharyngeal branch of vagus nerve32 NEUROANATOMY Vagus Nerve (X): Schema SEE ALSO PLATE 160 Glossopharyngeal nerve (IX) Meningeal branch of vagus nerve Auricular branch of vagus nerve Pharyngotympanic (auditory) tube Levator veli palatini muscle Salpingopharyngeus muscle Palatoglossus muscle Palatopharyngeus muscle Superior pharyngeal constrictor muscle Stylopharyngeus muscle Middle pharyngeal constrictor muscle Inferior pharyngeal constrictor muscle Cricothyroid muscle Trachea Esophagus Right subclavian artery Right recurrent laryngeal nerve Heart Cranial root of accessory nerve* (see next plate) Posterior nucleus of vagus nerve (parasympathetic and visceral afferent) Spinal tract and spinal nucleus of trigeminal nerve (somatic afferent) Solitary tract nucleus (visceral afferents including taste) Nucleus ambiguus (motor to pharyngeal and laryngeal muscles) Vagus nerve (X) Jugular foramen Superior ganglion of vagus nerve Inferior ganglion of vagus nerve Pharyngeal branch of vagus nerve (motor to muscles of palate and lower pharynx; sensory to lower pharynx) Communicating branch of vagus nerve to carotid branch of glossopharyngeal nerve Pharyngeal plexus Superior laryngeal nerve: Internal branch (sensory and parasympathetic) External branch (motor to cricothyroid muscle) Superior cervical cardiac branch of vagus nerve Inferior cervical cardiac branch of vagus nerve Thoracic cardiac branch of vagus nerve Left recurrent laryngeal nerve (motor to muscles of larynx except cricothyroid; sensory and parasympathetic to larynx below vocal folds; parasympathetic, efferent and afferent to upper esophagus and trachea) Pulmonary plexus 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 Cardiac plexus Esophageal plexus Gallbladder and bile ducts Liver Pyloric branch from hepatic plexus Pancreas Anterior vagal trunk Gastric branches of anterior vagal trunk (branches from posterior trunk behind stomach) Duodenum Ascending colon 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 Cecum Appendix Efferent fibers Afferent fibers Parasympathetic fibers33 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.34 NEUROANATOMY Hypoglossal Nerve (XII): Schema Intrinsic muscles of tongue Superior longitudinal Transverse and vertical Inferior longitudinal Styloglossus muscle Meningeal branch Hypoglossal nucleus Occipital condyle Inferior ganglion of vagus nerve Hypoglossal nerve (XII) (in hypoglossal canal) Ventral rami of C1, 2, 3 form ansa cervicalis of cervical plexus Superior cervical sympathetic ganglion Superior root of ansa cervicalis Internal carotid artery Inferior root of ansa cervicalis Ansa cervicalis Internal jugular vein Common carotid artery Sternothyroid muscle Sternohyoid muscle Omohyoid muscle (superior belly) Genioglossus muscle Geniohyoid muscle Hyoglossus muscle Thyrohyoid muscle Omohyoid muscle (inferior belly) Efferent fibers Afferent fibers35 NEUROANATOMY Nerves of Heart Vagus nerve (X) Superior cervical sympathetic ganglion (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 Recurrent laryngeal nerve Inferior cervical (sympathetic) cardiac nerves Thoracic cardiac branch of vagus nerve 4th thoracic sympathetic ganglion Thoracic (sympathetic) cardiac branches Cardiac plexus Phrenic nerve (cut) 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 3rd thoracic sympathetic ganglion Thoracic (sympathetic) cardiac branches Thoracic cardiac branch of vagus nerve Recurrent laryngeal nerve36 NEUROANATOMY Autonomic Nerves and Ganglia of Abdomen Right sympathetic trunk Thoracic duct Right greater and lesser splanchnic nerves Right phrenic nerve Inferior phrenic arteries and plexuses Right greater and lesser splanchnic nerves Right suprarenal plexus Right aorticoreena ganglion Right least splanchnic nerve Right renal artery and plexus Right sympathetic trunk White and gray rami communicantes Cisterna chyli Gray ramus communicans 3rd lumbar ganglion of sympathetic trunk 2nd and 3rd lumbar splanchnic nerves Right ureter and plexus Right testicular (ovarian) artery and plexus 4th lumbar splanchnic nerve 1st sacral ganglion of sympathetic trunk Gray rami communicantes Anterior, Posterior vagal trunks Left gastric artery and plexus Celiac ganglia Left greater splanchnic nerve Left lesser splanchnic nerve Splenic artery and plexus Common hepatic artery and plexus Superior mesenteric ganglion and plexus Left aorticorenal ganglion Left sympathetic trunk Intermesenteric (aortic) plexus Inferior mesenteric ganglion Left colic artery and plexus Inferior mesenteric artery and plexus 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 hypogasstri (pelvic) plexus Left sacral plexus Pelvic splanchnic nerves37 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 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 Plexus on inferior pancreaticoduodenal artery Superior mesenteric artery and plexus Plexus on first jejunal artery Plexus on anterior superior and anterior inferior pancreaticoduodenal arteries (posterior pancreaticoduodenal arteries and plexuses not visible in this view) Right gastric artery and plexus Hepatic plexus Vagal branch from hepatic plexus to pyloric part of stomach38 NEUROANATOMY Nerves of Stomach and Duodenum (continued) Plexus on gastro-omental (gastroepiploic) arteries Hepatic plexus Right gastric artery and plexus Posterior gastric branch of posterior vagal trunk Hepatic branch of anterior vagal trunk via lesser omentum Branch from hepatic plexus to cardia via lesser omentum Right inferior phrenic artery and plexus Posterior vagal trunk Celiac branch of posterior vagal trunk Celiac branch of anterior vagal trunk Left gastric artery and plexus Greater, lesser and least splanchnic nerves Left inferior phrenic artery and plexus Celiac ganglia and plexus Aorticorenal ganglia Splenic artery and plexus Right phrenic nerve Phrenic ganglion Branch from right inferior phrenic plexus to cardia of stomach Right and left inferior phrenic arteries and plexuses Anterior vagal trunk Posterior vagal trunk Greater, Lesser, Least splanchnic nerves View with stomach reflected cephalad Plexus on anterior superior and anterior inferior pancreaticoduoddena arteries Plexus on gastroduodenal artery Plexus on posterior superior and posterior inferior pancreaticoduodenal arteries Superior mesenteric ganglion and plexus Superior mesenteric ganglion and plexus Right greater, lesser and least splanchnic nerves Celiac ganglia Right aorticoreena ganglion Left aorticorenal ganglion Left greater, lesser and least splanchnic nerves Celiac branches of anterior and posterior vagal trunks Left gastric artery and plexus39 NEUROANATOMY Nerves of Small Intestine 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 Superior mesenteric artery and plexus Peritoneum (cut edge) Mesenteric branches Mesoappendix (contains appendicular artery and nerve plexus) Ileocolic artery and plexus40 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 Celiac ganglia and plexus Right lesser and least splanchnic nerves Right aorticoreena ganglion Superior mesenteric ganglion Middle colic artery and plexus Inferior pancreaticoduoddena arteries and plexuses Right colic artery and plexus Ileocolic artery and plexus Cecal and appendicular arteries and plexuses Right internal iliac artery and plexus (cut) Sacral sympathetic trunk Right sacral plexus Middle rectal artery and plexus Right inferior hypogastric (pelvic) plexus Vesical plexus Rectal plexus Urinary bladder Marginal artery and plexus Esophagus Left inferior phrenic artery and plexus Left gastric artery and plexus Left greater splanchnic nerve Left suprarenal plexus Left lesser and least splanchnic nerves Left aorticorenal ganglion Left renal artery and plexus 1st left lumbar splanchnic nerve Left lumbar sympathetic trunk Intermesenteric (aortic) plexus Left colic artery and plexus Inferior mesenteric ganglion, artery and plexus Sigmoid arteries and plexuses Superior hypogastric plexus Superior rectal artery and plexus Right and left hypogastric nerves Rectosigmoid artery and plexus Nerves from inferior hypogastric (pelvic) plexuses to sigmoid colon, descending colon and left colic (splenic) flexure Pelvic splanchnic nerves41 NEUROANATOMY Nerves of Kidneys, Ureters and Urinary Bladder 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 plexus42 NEUROANATOMY Nerves of Pelvic Viscera: Male Anterior vagal trunk Posterior vagal trunk and Celiac branch Inferior phrenic arteries and plexuses Left gastric artery and gastric plexus Celiac ganglia, plexus and trunk Left aorticorenal ganglion Superior mesenteric ganglion Superior mesenteric artery and plexus Intermesenteric (aortic) plexus Inferior mesenteric ganglion, artery and plexus Ureter and ureteric plexus Superior hypogastric plexus Superior rectal artery and plexus Hypogastric nerves Nerve from inferior hypogastric plexus to sigmoid and descending colon (parasympathetic) Sacral splanchnic nerves (sympathetic) Inferior hypogastric (pelvic) plexus Obturator nerve and artery Ductus deferens and plexus Vesical plexus Rectal plexus Prostatic plexus Cavernous nerves of penis Posterior scrotal nerves Dorsal nerve of penis Perineal nerve Inferior anal (rectal) nerve Levator ani muscle Pudendal nerve (Ischio-)coccygeus muscle and sacrospinous ligament Gluteus maximus muscle and sacrotubeerou ligament Piriformis muscle Sacral plexus Pelvic splanchnic nerves (parasympathetic) S1 spinal nerve (anterior ramus) Gray rami communicantes Lumbosacral trunk L5 spinal nerve (anterior ramus) 5th lumbar splanchnic nerve Sympathetic trunk and ganglia Gray rami communicantes 1st, 2nd, 3rd lumbar splanchnic nerves Gray White Rami communicantes L1 spinal nerve (anterior ramus) Left renal artery and plexus Diaphragm Greater Lesser Least Splanchnic nerves White and gray rami communicantes T10 spinal nerve (anterior ramus)43 NEUROANATOMY Nerves of Pelvic Viscera: Female Sympathetic trunk and L2 ganglion White and gray rami communicantes Lumbar splanchnic nerves Gray rami communicantes L5 spinal nerve Right hypogastric nerve (cut) Right and left sacral sympathetic trunks and ganglia Piriformis muscle Sacral splanchnic nerves (sympathetic) Pudendal nerve S5S4 S3S2 S1 Pelvic splanchnic nerves (parasympathetic) (Ischio-)coccygeus muscle Rectal plexus Rectum (retracted) Uterus (retracted) Uterovaginal plexus Vesical plexus Urinary bladder Symphyseal surface of pubis Ovary Uterine (fallopian) tube Inferior hypogastric (pelvic) plexus Left hypogastric nerve Right sympathetic trunk Uterus Right and left hypogastric nerves Sigmoid colon External iliac artery and plexus Internal iliac artery and plexus Common iliac artery and plexus Superior hypogastric plexus Superior hypogastric plexus Ureter Sacral promontory Ovarian artery and plexus Intermesenteric (aortic) plexus Ureter Common iliac vessels and plexus Extraperitoneal (subserous) fascia Abdominal aorta Inferior vena cava Peritoneum44 NEUROANATOMY Median Nerve Anterior view Note: Only muscles innervated by median nerve shown Musculocutaneous nerve Median nerve (C5, 6, 7, 8, T1) Inconstant contribution Pronator teres muscle (humeral head) Articular branch Flexor carpi radialis muscle Palmaris longus muscle Pronator teres muscle (ulnar head) Flexor digitorum superficialis muscle (turned up) Flexor digitorum profundus muscle (lateral part supplied by median [anterior interosseous] nerve; medial part supplied by ulnar nerve) Anterior interosseous nerve Flexor pollicis longus muscle Pronator quadratus muscle Palmar branch of median nerve Abductor pollicis brevis Opponens pollicis Superficial head of flexor pollicis brevis (deep head supplied by ulnar nerve) Thenar muscles1st and 2nd lumbrical muscles Dorsal branches to dorsum of middle and distal phalanges Medial Posterior Lateral Cords of brachial plexus Medial cutaneous nerve of arm Medial cutaneous nerve of forearm Axillary nerve Radial nerve Ulnar nerve Cutaneous innervation Palmar viewPosterior (dorsal) view Proper palmar digital nerves Common palmar digital nerves Communicating branch of median nerve with ulnar nerve45 NEUROANATOMY Ulnar Nerve Ulnar nerve (C7, 8, T1) (no branches above elbow) Inconstant contribution Medial epicondyle Articular branch (behind condyle) Flexor digitorum profundus muscle (medial part only; lateral part supplied by anterior interosseous branch of median nerve) Dorsal branch of ulnar nerve Flexor carpi ulnaris muscle (drawn aside) Palmar branch Superficial branch Deep branch Palmaris brevis Abductor digiti minimi Flexor digiti minimi brevis Opponens digiti minimi Hypothenar muscles Common palmar digital nerve Palmar and dorsal interosseous muscles Communicating branch of median nerve with ulnar nerve 3rd and 4th lumbrical muscles (turned down) Proper palmar digital nerves (dorsal digital nerves are from dorsal branch) Dorsal branches to dorsum of middle and distal phalanges Adductor pollicis muscle Posterior (dorsal) view Flexor pollicis brevis muscle (deep head only; superficial head and other thenar muscles supplied by median nerve) Palmar view Cutaneous innervation Anterior view Note: Only muscles innervated by ulnar nerve shown46 NEUROANATOMY Radial Nerve in Arm and Nerves of Posterior Shoulder Posterior view Suprascapular nerve (C5, 6) Dorsal scapular nerve (C5) Supraspinatus muscle Levator scapulae muscle (supplied also by branches from C3 and C4) Rhomboid minor muscle Rhomboid major muscle Infraspinatus muscle Teres major muscle Lower subscapular nerve (C5, 6) Posterior cutaneous nerve of arm (branch of radial nerve in axilla) Triceps brachii muscle Long head Lateral head Medial head Triceps brachii tendon Medial epicondyle Olecranon Anconeus muscle Extensor digitorum muscle Extensor carpi ulnaris muscle Extensor carpi radialis brevis muscle Extensor carpi radialis longus muscle Brachioradialis muscle Brachialis muscle (lateral part; remainder of muscle supplied by musculocutaaneou nerve) Lateral intermuscular septum Posterior cutaneous nerve of forearm Inferior lateral cutaneous nerve of arm Deltoid muscle Teres minor muscle Axillary nerve (C5, 6) Superior lateral cutaneous nerve of arm Radial nerve (C5, 6, 7, 8, T1) Inconstant contribution47 NEUROANATOMY Radial Nerve in Forearm Posterior view Radial nerve (C5, 6, 7, 8, T1) Inconstant contribution Superficial (terminal) branch Deep (terminal) branch Lateral epicondyle Anconeus muscle Brachioradialis muscle Extensor carpi radialis longus muscle Supinator muscle Extensor carpi radialis brevis muscle Extensor carpi ulnaris muscle Extensor-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 From radial nerve Inferior lateral cutaneous nerve of arm Superficial branch of radial nerve and dorsal digital branches Posterior cutaneous nerve of arm Posterior cutaneous nerve of forearm Cutaneous innervation from radial and axillary nerves Dorsal digital nerves48 NEUROANATOMY Sciatic Nerve and Posterior Cutaneous Nerve of Thigh Posterior cutaneous nerve of thigh (S1, 2, 3) Inferior cluneal nerves Perineal branches Tibial division of sciatic nerve Long head (cut) of biceps femoris muscle Adductor magnus muscle (also partially supplied by obturator nerve) Semitendinosus muscle Semimembranosus muscle Tibial nerve Articular branch Plantaris muscle Medial sural cutaneous nerve Gastrocnemius muscle Sural nerve Soleus muscle Tibial nerve Medial calcaneal branches Medial and lateral plantar nerves Greater sciatic foramen Sciatic nerve (L4, 5, S1, 2, 3) Common fibular (peroneal) division of sciatic nerve Short head of biceps femoris muscle Cutaneous innervation Long head (cut) of biceps femoris muscle Common fibular (peroneal) nerve Articular branch Lateral sural cutaneous nerve Sural communicating branch Posterior cutaneous nerve of thigh From sciatic nerve Lateral calcaneal branches Lateral dorsal cutaneous nerve Common fibular (peroneal) nerve via lateral sural cutaneous nerve Medial sural cutaneous nerve Superficial fibular (peroneal) nerve Sural nerve Tibial nerve via medial calcaneal branches49 NEUROANATOMY Tibial Nerve Tibial nerve (L4, 5, S1, 2, 3) Medial sural cutaneous nerve (cut) Articular branches Plantaris muscle Gastrocnemius muscle (cut) Nerve to popliteus muscle Popliteus muscle Interosseous nerve of leg Soleus muscle (cut and partly retracted) Flexor digitorum longus muscle Tibialis posterior muscle Flexor hallucis longus muscle Sural nerve (cut) Lateral calcaneal branch Medial calcaneal branch Flexor retinaculum (cut) Lateral dorsal cutaneous nerve Common fibular (peroneal) nerve Lateral sural cutaneous nerve (cut) Medial calcaneal branches (S1, 2) Medial plantar nerve (L4, 5) Lateral plantar nerve (S1, 2) From tibial nerveSaphenous nerve (L3, 4) Sural nerve (S1, 2) via lateral calcaneal and lateral dorsal cutaneous branches Cutaneous innervation of sole 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 Quadratus plantae muscle and nerve Nerve to abductor digiti minimi muscle 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 Note: Articular branches not shown Articular branch50 NEUROANATOMY Common Fibular (Peroneal) Nerve Common fibular (peroneal) nerve (phantom) Biceps femoris tendon Common fibular (peroneal) nerve (L4, 5, S1, 2) Head of fibula Fibularis (peroneus) longus muscle (cut) Superficial fibular (peroneal) nerve Branches of lateral sural cutaneous nerve Fibularis (peroneus) longus muscle Fibularis (peroneus) brevis muscle Medial dorsal cutaneous nerve Intermediate dorsal cutaneous nerve Inferior extensor retinaculum (partially cut) Lateral dorsal cutaneous nerve (branch of sural nerve) Dorsal digital nerves Lateral sural cutaneous nerve (phantom) Articular branches Recurrent articular nerve Extensor digitorum longus muscle (cut) Deep fibular (peroneal) nerve Tibialis anterior muscleCutaneous innervation Extensor digitorum longus muscle Extensor hallucis longus muscleLateral sural cutaneous nerve 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 branchPart 2 Neurophysiology Organization of the Brain: Cerebrum. . . . . . . 52 Organization of the Brain: Cell Types. . . . . . . 53 Blood-Brain Barrier . . . . . . . . . . . . . . . . . . . . . 54 Synaptic Transmission: Morphology of Synapses . . . . . . . . . . . . . . . 55 Synaptic Transmission: Neuromuscular Junction . . . . . . . . . . . . . . . 56 Synaptic Transmission: Visceral Efferent Endings . . . . . . . . . . . . . . . 57 Synaptic Transmission: Inhibitory Mechanisms . . . . . . . . . . . . . . . . 58 Synaptic Transmission: Chemical Synaptic Transmission . . . . . . . . . 59 Synaptic Transmission: Temporal and Spatial Summation . . . . . . . . 60 Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition . . . . 61 Cerebrospinal Fluid (CSF): Circulation of CSF . . . . . . . . . . . . . . . . . . . . 62 Spinal Cord: Ventral Rami. . . . . . . . . . . . . . . . 63 Spinal Cord: Membranes and Nerve Roots . . 64 Peripheral Nervous System . . . . . . . . . . . . . . . 65 Autonomic Nervous System: Schema. . . . . . . 66 Autonomic Nervous System: Cholinergic and Adrenergic Synapses . . . . . 67 Hypothalamus . . . . . . . . . . . . . . . . . . . . . . . . . 68 Limbic System . . . . . . . . . . . . . . . . . . . . . . . . . 69 The Cerebral Cortex . . . . . . . . . . . . . . . . . . . . 70 Descending Motor Pathways . . . . . . . . . . . . . 71 Cerebellum: Afferent Pathways. . . . . . . . . . . . 72 Cerebellum: Efferent Pathways . . . . . . . . . . . . 73 Cutaneous Sensory Receptors. . . . . . . . . . . . . 74 Cutaneous Receptors: Pacinian Corpuscle. . . . . . . . . . . . . . . . . . . . 75 Proprioception and Reflex Pathways: I . . . . . . 76 Proprioception and Reflex Pathways: II . . . . . 77 Proprioception and Reflex Pathways: III . . . . 78 Proprioception and Reflex Pathways: IV. . . . . 79 Sensory Pathways: I . . . . . . . . . . . . . . . . . . . . . 80 Sensory Pathways: II . . . . . . . . . . . . . . . . . . . . 81 Sensory Pathways: III. . . . . . . . . . . . . . . . . . . . 82 Visual System: Receptors. . . . . . . . . . . . . . . . . 83 Visual System: Visual Pathway . . . . . . . . . . . . 84 Auditory System: Cochlea . . . . . . . . . . . . . . . . 85 Auditory System: Pathways . . . . . . . . . . . . . . . 86 Vestibular System: Receptors . . . . . . . . . . . . . 87 Vestibular System: Vestibulospinal Tracts. . . . 88 Gustatory (Taste) System: Receptors . . . . . . . 89 Gustatory (Taste) System: Pathways . . . . . . . . 90 Olfactory System: Receptors . . . . . . . . . . . . . . 91 Olfactory System: Pathway . . . . . . . . . . . . . . . 92 Click any title below to link to that plate.52 NEUROPHYSIOLOGY Organization of the Brain: Cerebrum Central sulcus (Rolando) Precentral gyrus Postcentral gyrus Postcentral sulcus Superior parietal lobule Inferior parietal lobule Supramarginal gyrus Angular gyrus Parietooccipital sulcus Occipital pole Calcarine sulcus Inferior temporal gyrus Middle temporal gyrus Superior temporal gyrus Temporal pole Lateral sulcus (Sylvius) Frontal pole Precentral sulcus Frontal lobe Parietal lobe Temporal lobe Occipital lobe Insula (island of Reil) FIGURE 2.1 ORGANIZATION OF THE BRAIN: CEREBRUM• The cerebral cortex represents the highest center for sensory and motor processing. In general, the frontal lobe processes motor, visual, speech, and personality modalities. The parietal lobe processes sensory information; the temporal lobe, auditory and memory modalities; and the occipital lobe, vision. The cerebellum coordinates smooth motor activities and processes muscle position. The brainstem (medulla, pons, midbrain) conveys motor and sensory information and mediates important autonomic functions. The spinal cord receives sensory input from the body and conveys somatic and autonomic motor information to peripheral targets (muscles, viscera). ©53 NEUROPHYSIOLOGY Organization of the Brain: Cell Types Red: Blue: Purple: Gray: Motor neuron Sensory neuron Interneuron Glial and neurilemmal cells and myelin Multipolar (pyramidal) cell of cerebral motor cortex Astrocyte Multipolar somatic motor cell of nuclei of cranial nn. Multipolar cell of lower brain motor centers Oligodendrocyte Corticospinal (pyramidal) fiber Axodendritic ending Axosomatic ending Axoaxonic ending Multipolar somatic motor cell of anterior horn of spinal cord Collateral Renshaw interneuron (feedback) Myelinated somatic motor fiber of spinal nerve Myelin sheath Motor endplate with Schwann cell cap Striated (voluntary) muscle Striated (somatic) muscle Motor endplate Interneurons Interneuron Astrocyte Bipolar cell of cranial n. Unipolar cell of sensory ganglia of cranial nn. Satellite cells Schwann cell Free nerve endings (unmyelinated fibers) Encapsulated ending Specialized ending Muscle spindle Unipolar sensory cell of dorsal spinal root ganglion Satellite cells Myelinated afferent fiber of spinal nerve Myelin sheath Schwann cells Unmyelinated fibers Free nerve endings Encapsulated ending Muscle spindle Autonomic preganglionic (sympathetic or parasympatthetic nerve fiber Myelin sheath Autonomic postganglionic neuron of sympathetic or parasympathetic ganglion Satellite cells Unmyelinated nerve fiber Schwann cells Beaded varicosities and endings on smooth muscle and gland cells Endings on cardiac muscle or nodal cells Multipolar visceral motor (autonomic) cell of spinal cord Blood vessel Note: Cerebellar cells not shown here FIGURE 2.2 ORGANIZATION OF THE BRAIN: CELL TYPES• Neurons form the functional cellular units responsible for communication, and throughout the nervous system, they 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 speciallize cells that optimize neuronal function, provide maintenaanc functions, or protect the nervous system. ©54 NEUROPHYSIOLOGY Blood-Brain Barrier Basement membrane Cell membrane Cytoplasm Tight junction proteins Astrocyte foot processes Astrocyte Capillary endothelial cell Tight junction Capillary lumen Red blood cell 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 junctiion and astrocytic foot processes that abut the endothelium and its basement membrane. The movement of large molecules and other substances (including many drugs) from the blood to the interstitial space of the CNS is restricted by the BBB. CNS endotheliia cells also exhibit a low level of pinocytotic activity across the cell, so specific carrier systems for the transport of essential substrrate 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 Kand neurotransmmitter from the interstitial fluid. ©55 NEUROPHYSIOLOGY Synaptic Transmission: Morphology of Synapses 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 transmittter 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. Dendrite Node Axon Myelin sheath Dendrites Axolemma Mitochondria Postsynaptic cell Enlarged section of boutonAxon (axoplasm) Glial process Synaptic vesicles Synaptic cleft Presynaptic membrane (densely staining) Postsynaptic membrane (densely staining) Numerous boutons (synaptic knobs) of presynaptic neurons terminating on a motor neuron and its dendrites ©56 NEUROPHYSIOLOGY Synaptic Transmission: Neuromuscular Junction Structure of Neuromuscular Junction Active zone Schwann cell process Acetylcholine receptor sites Myofibrils Synaptic cleft Postsynaptic membrane Junctional fold Sarcoplasm Acetylcholine receptor sites Myelin sheath Neurilemma Axoplasm Schwann cell Mitochondria Basement membrane Nucleus of Schwann cell Presynaptic membrane Active zone Synaptic vesicles Synaptic trough Basement membrane Sarcolemma Nucleus of muscle cell FIGURE 2.5 STRUCTURE OF THE NEUROMUSCULAR JUNCTION• Motor axons that synapse on skeletal muscle form expanded terminaal 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 accumulaat adjacent to the presynaptic membrane and, when appropriattel stimulated, release their neurotransmitter into the synaptic cleft. The transmitter then binds to receptors that mediate depolarizaatio of the muscle sarcolemma and initiate a muscle action potential. A single muscle fiber has only one neuromuscular junctiion but a motor axon can innervate multiple muscle fibers. ©57 NEUROPHYSIOLOGY Synaptic Transmission: Visceral Efferent Endings 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 postsynappti terminals observed in neuronal and neuromuscular junctiio synapses. Rather, neurotransmitter substances are released into interstitial spaces (A and B) or into the bloodstream (C, neurosecrretion from expanded nerve terminal endings. This arrangemeen 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. Pituicyte processes Visceral Efferent Endings A. Smooth muscle Smooth muscle cells (cut) Schwann cell cap enclosing nerve axons Schwann cell cap Smooth muscle cells Varicosities Terminal endings B. Gland (submandibular) Sympathetic terminal ending Varicosity Schwann cell cap Schwann cell cap enclosing nerve axons Mucous cells Varicosity Parasympathetic terminal ending Serous cells Schwann cell cap enclosing nerve axons C. Neurosecretory (posterior pituitary) Axon Axon Fibroblast Neurosecretory vesicles Collagen space Basement membrane Mast cell Endothelium Capillary ©58 NEUROPHYSIOLOGY 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. Synaptic Transmission: Inhibitory Mechanisms A. Only E fires 90-mV spike in E terminal B. Only I fires Long-lasting partial depolarization in E terminal EPSP in motor neuron 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 E (Excitatory fiber) E (Excitatory fiber) I (Inhibitory fiber) I (Inhibitory fiber) Motor neuron Motor neuron Axon Axon 20 70 60 70 60 70 20 70 60 70 70 60 70mV mV 80 mV 90 mV A′. Only E fires EPSP in motor neuron 70 80 B′. Only I fires Motor neuron hyperpolaarize 70 60 80 C′. I fires before E Depolarizatiio of motor neuron less than if only E fires ©59 NEUROPHYSIOLOGY Synaptic Transmission: Chemical Synaptic Transmission FIGURE 2.8 CHEMICAL SYNAPTIC TRANSMISSION• Chemical synaptic transmission between neurons may be excitatoor or inhibitory. During excitation (left column), a net increase in the inward flow of Nacompared with the outward flow of Kresults 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 Kand Clchannels drives the membrane potential away from threshold (hyperpolarization) and decreases the probabillit that the neuron will reach threshold (inhibitory postsynaptic potential [IPSP]) for an action potential. Excitatory Inhibitory When impulse reaches excitatory synaptic bouton, it causes release of a transmitter substance into synaptic cleft. This increases permeability of postsynaptic membrane to Naand K. More Namoves into postsynappti cell than Kmoves out, due to greatee electrochemical gradient Resultant net ionic current flow is in a directiio that tends to depolarize postsynaptic cell. If depolarization reaches firing threshold, an impulse is generated in postsynaptic cell At inhibitory synapse, transmitter substance releaase by an impulse increases permeability of the postsynaptic membrane to Cl. Kmoves out of post-synaptic cell but no net flow of Cloccurs at resting membrane potential Resultant ionic current flow is in direction that tends to hyperpolarize postsynaptic cell. This makes depolarizatiio by excitatory synapses more difficult—more depolarizattio is required to reach threshold Synaptic vesicles in synaptic bouton Presynaptic membrane Transmitter substances Synaptic cleft Postsynaptic membrane Synaptic bouton ClKNaCurrent Potential Potential (mV) 700 4 8msec Current flow and potential change 12 16 65 Current Potential Potential (mV) 700 4 8 msec Current flow and potential change 12 16 75 ©60 NEUROPHYSIOLOGY Synaptic Transmission: Temporal and Spatial Summation FIGURE 2.9 TEMPORAL AND SPATIAL SUMMATION • Neurons receive multiple excitatory and inhibitory inputs. Temporra summation occurs when a series of subthreshold impulses in one excitatory fiber produces an action potential in the postsynaptti cell (panel C). Spatial summation occurs when subthreshold impulses from two or more different fibers trigger an action potentiia (panel D). Both temporal and spatial summation can be modulaate by simultaneous inhibitory input (panel E). Inhibitory and excitatory neurons use a wide variety of neurotransmitters, some of which are summarized here. AxonmV –70 AxonmV –70 AxonmV –70 AxonmV –70 AxonmV –70 AxonmV –70 Temporal and Spatial Summation of Excitation and Inhibition Excitatory fibers Inhibitory fibers Excitatory fibers Inhibitory fibers Excitatory fibers Inhibitory fibers Excitatory fibers Inhibitory fibers Excitatory fibers Inhibitory fibers Excitatory fibers Inhibitory fibers A. Resting state: motor nerve cell shown with synaptic boutons of excitatory and inhibitory nerve fibers ending close to it B. Partial depolarization: impulse from one excitatory fiber has caused partial (below firing threshold) depolarization of motor neuron C. Temporal excitatory summation: a series of impulses in one excitatory fiber together produce a suprathreshold depolarization that triggers an action potential E. Spatial excitatory summation with inhibition: impulses from two excitatory fibers reach motor neuron but impulses from inhibitory fiber prevent depolarization from reaching threshold E. (continued): motor neuron now receives additional excitatory impulses and reaches firing threshold despite a simultaneous inhibitory impulse; additional inhibitory impulses might still prevent firing D. Spatial excitatory summation: impulses in two excitatory fibers cause two synaptic depolarizations that together reach firing threshold triggering an action potential Transmitter Location Acetylcholine Neuromuscular junction, autonomic endinng and ganglia, CNS Biogenic amines Norepinephrine Sympathetic endings, CNS Dopamine CNS Serotonin CNS, GI tract Amino acids -Aminobutyric CNS acid (GABA) Glutamate CNS Purines Adenosine CNS Adenosine CNS triphosphate (ATP) Transmitter Location Gas Nitric oxide CNS, GI tract Peptides -Endorphins CNS, GI tract Enkephalins CNS Antidiuretic CNS (hypothalamus/posterior hormone pituitary) Pituitary-releasing CNS (hypothalamus/anterior hormones pituitary) Somatostatin CNS, GI tract Neuropeptide Y CNS Vasoactive intestinal peptide CNS, GI tract CHART 2.1 SUMMARY OF SOME NEUROTRANSMITTERS AND WHERE WITHIN THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM THEY ARE FOUND CNS, Central nervous system; GI, gastrointestinal. ©61 NEUROPHYSIOLOGY FIGURE 2.10 BRAIN VENTRICLES AND CSF COMPOSITION• CSF circulates through the four brain ventricles (two lateral ventriclle and a third and fourth ventricle) and in the subarachnoid space surrounding the brain and spinal cord. The electrolyte composiitio 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). Cerebrospinal Fluid (CSF): Brain Ventricles and CSF Composition Left lateral phantom view Right lateral ventricle Left interventricular foramen (Monro) 3rd ventricle Frontal (anterior) horn Central part Temporal (inferior) horn Occipital (posterior) horn Left lateral ventricle Cerebral aqueduct (Sylvius) 4th ventricle Left lateral recess Central canal of spinal cord Median aperture (foramen of Magendie) Left lateral aperture (foramen of Luschka) © CSF Blood Plasma Na(mEq/L) 140–145 135–147 K(mEq/L) 3 3.5–5.0 Cl− (mEq/L) 115–120 95–105 HCO3− (mEq/L) 20 22–28 Glucose (mg/dL) 50–75 70–110 Protein (g/dL) 0.05–0.07 6.0–7.8 pH 7.3 7.35–7.45 CHART 2.2 CSF COMPOSITION62 NEUROPHYSIOLOGY Cerebrospinal Fluid (CSF): Circulation of CSF FIGURE 2.11 CIRCULATION OF CEREBROSPINAL FLUID• CSF circulates through the four brain ventricles (two lateral ventriclle and a third and fourth ventricle) and in the subarachnoid space surrounding the brain and spinal cord. Most of the CSF is reabsorbed into the venous system through the arachnoid granulatiion and through the walls of the capillaries of the central nervous system and pia mater. Interventricular foramen (Monro) Arachnoid granulations Superior sagittal sinus Subarachnoid space Median aperture (foramen of Magendie) Central canal of spinal cord Subarachnoid space Arachnoid Arachnoid Dura mater Cistern of corpus callosum Choroid plexus of lateral ventricle (phantom) Dura mater Choroid plexus of 4th ventricle Lateral aperture (foramen of Luschka) Cerebral aqueduct (Sylvius) Choroid plexus of 3rd ventricle ©63 NEUROPHYSIOLOGY 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. Spinal Cord: Ventral Rami Lumbar plexus L5 vertebra Sacral plexus Sciatic nerve Coccyx Filaments of spinal nerve roots (T7 and T8) L1 vertebra Coccygeal nerve Base of skull C1 spinal nerve C8 spinal nerve T1 spinal nerve 1st rib 12th rib Intercostal nerves T12 spinal nerveConus medullaris L1 spinal nerve Cauda equina S1 spinal nerve Sacrum (cut away) Termination of dural sac C1 vertebra (atlas) Cervical plexus Brachial plexus Spinal dura mater ©64 NEUROPHYSIOLOGY 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 innervaat skeletal muscle, and sensory fibers convey information back to the central nervous system from the skin, skeletal muscles, and joints. The spinal cord is ensheathed in three meningeal coverings: the outer, tough dura mater; the arachnoid mater; and the pia mater, which intimately ensheaths the cord itself. CSF bathes the cord and is found in the subarachnoid space. Arachnoid mater Posterior view Membranes removed: anterior view (greatly magnified) Gray and white rami communicantes Gray matter White matter Subarachnoid space Pia mater overlying spinal cord Filaments of dorsal root 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 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 Spinal Cord: Membranes and Nerve Roots ©65 NEUROPHYSIOLOGY Peripheral Nervous System 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 systeems 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. Sensory neuron cell body Dorsal root ganglion Dorsal root Posterior horn Anterior horn Motor neuron cell body Motor neuron Neuromuscular junction Muscle Skin Sensory neuron Ventral root Peripheral nerve Axon Myelin sheath © with66 NEUROPHYSIOLOGY Autonomic Nervous System: Schema 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 twoneuuro chain, with the preganglionic neuron arising from the central nervous system and synapsing on a postganglionic neuron located in a peripheral autonomic ganglion. Postganglionic axons of the autonoomi 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, digestiion and associated glandular activity). Intracranial vessels Ciliary ganglion Eye Pterygopalatine ganglion Lacrimal glands Otic ganglion Parotid glands Sublingual and submandibular glands Peripheral cranial and facial vessels Larynx Trachea Bronchi Lungs Heart Stomach Pancreas Suprarenal glands Kidneys Intestines Descending colon Sigmoid colon Urinary bladder Prostate External genitalia Rectum Submandibular ganglion Pulmonary plexus Cardiac plexus Celiac ganglion Aorticorenal ganglion Superior mesenteric ganglion Inferior mesenteric ganglion Superior hypogastric plexus Inferior hypogastric plexus Lumbar splanchnic nerves Splanchnic nerves Greater Lesser Least Pelvic splanchnic nerves Presynaptic Postsynaptic Antidromic conduction Presynaptic Postsynaptic Sympathetic fibers Parasympathetic fibers Oculomotor nerve (III) Facial nerve (VII) Glossopharyngeal nerve (IX) Medulla oblongata Vagus nerve (X) Sweat gland Peripheral blood vessel Arrector (smooth) muscle of hair follicle Note: Above three structures are shown at only one level but occur at all levels Note: Blue-shaded areas indicate zones of parasympathetic outflow from CNS Coccygeal S5 S4 S3 S2S1 L5 L4 L3 L2 L1 T12 T9T8 T7 T6 T5 T4 T3 T2 T1 C8 C7 C6 C5 C4 C3 C2 C1T11 T10 Gray rami communicantes Gray and white rami communicantes Gray ramicommunicantes Liver Gallbladder Bile ducts ©67 NEUROPHYSIOLOGY Autonomic Nervous System: Cholinergic and Adrenergic Synapses 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 noradrenallin (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 gammaaminobbutyri acid (GABA), substance P, enkephalins, histamine, glutamic acid, neuropeptide Y, and others. Somatic fibers Antidromic conduction Medulla oblongata Thoracic part of spinal cord Sacral part of spinal cord Upper lumbar part of spinal cord (L1-2 [3]) Cervical sympathetic ganglia Gray ramus communicans Glossopharyngeal nerve (IX) Internal carotid nerve Vagus nerve (X) White ramus communicans Celiac ganglion Superior mesenteric ganglion Inferior mesenteric ganglion Pelvic splanchnic nerves C Cholinergic synapses A Adrenergic synapses Parotid gland Larynx Trachea Bronchi Lungs Heart Striated muscle Sweat glands Hair follicles Peripheral arteries Visceral arteries Gastrointestinal tract Urinary bladder Urethra Prostate Presynaptic Postsynaptic Presynaptic Postsynaptic Sympathetic fibers Parasympathetic fibers Suprarenal gland ©68 NEUROPHYSIOLOGY Hypothalamus 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 temperatuur regulation, food intake, water intake, many of the endocrine systems (see Chapter 8), motivation, and emotional behavior. It receives inputs from the reticular formation (sleep/wake cycle information), the thalamus (pain), the limbic system (emotion, fear, anger, smell), the medulla oblongata (blood pressure and heart rate), and the optic system, and it integrates these inputs for regulatiio of the functions listed. Anterior lobe of pituitaryOptic chiasm Optic (II) nerve Olfactory tract Medial preoptic nucleus Lateral preoptic nucleus Lateral ventricle Medial forebrain bundle Anterior commissure Septum pellucidum Fornix Corpus callosum From hippocampal formation Interthalamic adhesion Thalamus Lateral hypothalamic area Paraventricular nucleus Anterior hypothalamic area Dorsal hypothalamic area Dorsomedial nucleusMamillothalamic tract Posterior area Periventricular nucleus Nucleus intercalatus Fornix Ventromedial nucleus Tuberohypophyseal tract Supraoptic nucleus Supraopticohypophyseal tract Posterior lobe of pituitary Oculomotor (III) nerve Mamillary complex Red nucleus Cerebral peduncle Dorsal longitudinal fasciculus Descending hypothalamic connections PonsReticular formation Hypothalamic Area Major Functions* Preoptic and anterior Heat loss center: cutaneous vasodilation and sweating Posterior Heat conservation center: cutaneous vasoconstriction and shivering Lateral Feeding center: eating behavior Ventromedial Satiety center: inhibits eating behavior Supraoptic (subfornical organ and organum vasculosum) ADH and oxytocin secretion (sensation of thirst) Paraventricular ADH and oxytocin secretion Periventricular Releasing hormones for the anterior pituitary CHART 2.3 MAJOR FUNCTIONS OF THE HYPOTHALAMUS *Stimulation of the center causes the responses listed. ©69 NEUROPHYSIOLOGY Limbic System FIGURE 2.18 HIPPOCAMPUS AND FORNIX• The limbic system includes the hypothalamus and a collection of interconnected structures in the telencephalon (cingulate, parahippocaampal and subcallosal gyri), as well as the amygdala and hippocaampa formation. The limbic system functions in linking emotiio and motivation (amygdala), learning and memory (hippocamppa formation), and sexual behavior (hypothalamus). 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 Amygdaloid bodies Mamillary bodies Columns of fornix Body of fornix Commissure of fornix Crura of fornix Hippocampus with fimbria ©70 NEUROPHYSIOLOGY The Cerebral Cortex FIGURE 2.19 CEREBRAL CORTEX: LOCALIZATION OF FUNCTION AND ASSOCIATION PATHWAYS• The cerebral cortex is organized into functional regions. In additiio to specific areas devoted to sensory and motor functions, there are areas that integrate information from multiple sources. The cerebral cortex participates in advanced intellectual functions, including aspects of memory storage and recall, language, higher cognitive functions, conscious perception, sensory integration, and planning/execution of complex motor activity. General cortical areas associated with these functions are illustrated. Motor control of speech Prefrontal; inhibitory control of behavior; higher intelligence Premotor; orientation; eye and head movements Motor Ms I Ms II Sensory Sm I Sm II Motor Ms I Ms II Sensory Sm I Sm III ? Sensory analysis Visual I Visual II Visual III Language; reading; speech Auditory I Auditory II Olfactory Cingulate gyrus (emotional behavior) and cingulum Prefrontal; inhibitory control of behavior; higher intelligence Premotor Visual I Visual II Visual III Corpus callosum Hippocampal commissure Anterior commissure ©71 NEUROPHYSIOLOGY 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 neuroon) The anterior horn cells and their associated axons constitute the lower portion of the system (lower motor neuron). Descending Motor Pathways Basis pedunculi Hip TrunkShoulder ElbowWrist FingersThumbNeckBrowEyelidNaresLips TongueLar ynx Knee Ankle Toes Basis pontis Pyramids Midbrain Internal capsule Motor cortex Pons Medulla Medulla Spinal cord Above midthorraci level Below midthorraci level Decussation of pyramids Anterior corticospinal tract Lateral corticospinal tract Motor endplate Motor endplate Motor system Fibers originate in motor cortex and descend via posterior limb of internal capsule to basis pedunculi of midbrain Longitudinal bundles branch upon entering basis pontis and rejoin to enter pyramids of medulla At lower medulla, bulk of fibers cross median plane to form lateral corticospinal tract; some fibers continue downward in ipsilateral lateral corticospinal tract; others descending ipsilateral anterior corticospinal tract Synapse occurs at spinal level: Lateral corticospinal fibers synapse on ipsilateral anterior horn cells; anterior corticospinal fibers synapse on contralateral anterior horn cells Lateral aspect of cerebral cortex to show topographic projection of motor centers on precentral gyrus ©72 NEUROPHYSIOLOGY 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 spinocerebelllum 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 paleocerebelllu 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 coordinaate 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). Schema of theoretical “unfolding” of cerebellar surface in derivation of above diagram Cortical input Nucleus reticularis tegmenti pontis 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 spinocerebbella tract Superior cerebellar peduncle Middle cerebellar peduncle To contralateral cerebellar cortex Primary fissure Leg Arm Face To nodule and flocculus Inferior cerebellar peduncle Vestibular nuclei 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 Neocerebellum (pontocerebellum) Middle vermis Hemisphere Paleocerebellum (spinocerebellum) Uvula Pyramid Vermis Archicerebbellu (vestibulocerebbellum Lingula Flocculus Nodule 2nd spinal projection area (gracile lobule) Leg zone Arm zone Face zone Hemisphere Vermis Lateral part Intermeddiat part Anterior lobe Primary fissure Middle (posterior) lobe Posterolateral fissure Flocculonoddula lobe Cerebellum: Afferent Pathways ©73 NEUROPHYSIOLOGY FIGURE 2.22 CEREBELLAR EFFERENT PATHWAYS• The cerebellum plays an important role in coordinating movement. It influences descending motor pathways to produce fine, smooth, and coordinated motion. The archicerebellum is primarily 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 planniin of motor activity (e.g., seeing a pencil and then planning and executing the movement of the arm and hand to pick it up). Cerebellum: Efferent Pathways Section A–B viewed from below Section B–C viewed from above Planes of section: red arrows indicate direction of view Pontomedullary reticular formation Medulla oblongata Lateral reticular nucleus Inferior olive Inferior cerebellar peduncle Vestibular nuclei Cerebellar cortex Dentate nucleus Emboliform nucleus Globose nuclei Fastigial nucleus Red nucleus Mesencephalic reticular formation Ventral anterior and ventral lateral nuclei of thalamus Inhibitory endings of Purkinje cells Excitatory endings Motor and premotor cerebral cortex Internal capsule Cerebral peduncle Decussation of superior cerebellar peduncles Descending fibers from superior cerebellar peduncles Hook bundle of Russell A B C ©74 NEUROPHYSIOLOGY FIGURE 2.23 SKIN AND CUTANEOUS RECEPTORS• Cutaneous receptors respond to touch (mechanoreceptors), pain (nociceptors), and temperature (thermoreceptors). Several different types of receptors are present in skin. Meissner’s corpuscles have small receptive fields and respond best to stimuli that are applied at low frequency (i.e., flutter). The pacinian corpuscles are located in the subcutaneous tissue and have large receptive fields. They respond best to high-frequency stimulation (i.e., vibration). Merkel’s discs have small receptive fields and respond to touch and pressure (i.e., indenting the skin). Ruffini’s corpuscles have large receptive fields, and they also respond to touch and pressure. Free nerve endings respond to pain and temperature. Subcutaneous artery and vein Cutaneous nerve Motor (autonomic) nerve Skin ligaments (retinacula cutis) Elastic fibers Sensory nerves Vein Artery Pacinian corpuscle Papilla of hair follicle Hair matrix Sweat gland Hair cuticle Hair follicle Connective tissue layer Glassy membrane External sheath Internal sheath Cuticle Sebaceous gland Arrector muscle of hair MelanocyteHair shaft Free nerve endings Meissner’s corpuscle Pore of sweat gland Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Dermal papilla (of papillary layer) Reticular layer Epidermis Dermis Subcutaneous tissue Cross section Detail of free nerve ending Detail of Merkel’s disc Mitochondria Basal epithelial cells Cytoplasmic protrusion Lobulated nucleus Granulated vesicles Expanded axon terminal Schwann cell Desmosomes Merkel cell Schwann cells Axon Basement membrane Axon terminal Mitochondrion Schwann cell Cutaneous Sensory Receptors ©75 NEUROPHYSIOLOGY FIGURE 2.24 PACINIAN CORPUSCLE• Pacinian corpuscles are mechanoreceptors that transduce mechanicca forces (displacement, pressure, vibration) into action potentials that are conveyed centrally by afferent nerve fibers. As the viscoellasti 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. Cutaneous Receptors: Pacinian Corpuscle Pressure Na+ A. Sharp “on and off” changes in pressure at start and end of pulse applied to lamellated capsule are transmitted to central axon and provoke generator potentials, which in turn may trigger action potentials; there is no response to a slow change in pressure gradient. Pressure at central core and, accordingly, generator potentials are rapidly dissipated by viscoelastic properties of capsule (Action potentials may be blocked by pressure at a node or by drugs) B. In absence of capsule, axon responds to slow as well as to rapid changes in pressure. Generator potential dissipates slowly, and there is no “off” response Pressure applied to axon terminal directly or via capsule causes increased permeability of membrane to Na+, thus setting up ionic generator current through 1st node If resultant depolarization at 1st node is great enough to reach threshold, an action potential appears which is propagated along nerve fiber Pacinian Corpuscle as Pressure Transducer 1st node Myelin sheath Lamellated capsule Central core Unmyelinated axon terminal To amplifier Pressure Generator potential Action potential To amplifier Pressure Generator potential Action potential ©76 NEUROPHYSIOLOGY 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 involviin several spinal cord segments (top and bottom figures of upper panel) initiate muscle contraction reflexes. The lower panel shows the somatotopic distribution of the motor neuron cell bodies in the ventral horn of the spinal cord that innervate limb muscles (flexor and extensor muscles of upper and lower limbs). Proprioception and Reflex Pathways: I In cervical enlargement of spinal cord In lumbar enlargement of spinal cord Proprioceptive fibers Dorsal horn interneuron Flexor reflex interneuron Dorsal horn interneuron Dorsal horn interneuron From cutaneous receptor From muscle spindle Dorsal root ganglion Ventral root motor axon From motor neuron To motor neuron To motor neuron Schematic representation of motor neurons Spinal Effector Mechanisms Flexors Extensors Flexors Extensors ©77 NEUROPHYSIOLOGY Detail of muscle spindle Efferent fibers Afferent fibers Afibers from Golgi-type endings Afibers from paciniform corpuscles and Ruffini terminals Aand C fibers from free nerve endings Extrafusal muscle fiber Intrafusal muscle fibers Sheath Lymph space Nuclear bag fiber Nuclear chain fiber Ib (A) fibers from Golgi tendon organs (proprioception) Alpha motor neuron to extrafusal muscle fiber end plates Gamma motor neuron to intrafusal muscle fiber and plates II (A) fiber from flower spray endings Ia (A) fiber from annulospiral endings IV (unmyelinated) fibers from free nerve endings (pain) III (A) fibers from free nerve endings and from some specialized endings (pain and some pressure) II (A) fibers from flower spray endings (proprioception); from paciniform corpuscles (pressure) and pacinian corpuscles (pressure) Ia (A) fibers from annulospiral endings (proprioception) Gamma motor neurons to intrafusal striated muscle end plates Alpha motor neurons to extrafusal striated muscle end plates Proprioception and Reflex Pathways: II FIGURE 2.26 MUSCLE AND JOINT RECEPTORS• Muscle spindles and Golgi tendon organs send afferent signals to the brain to convey the position of limbs and help coordinate musccl movement. Muscle spindles convey information on muscle tensiio and contraction (dynamic forces) and muscle length (static forces). The nuclear bag fibers respond to both dynamic and static forces, whereas the nuclear chain fibers respond to static forces. Intrafusal fibers maintain appropriate tension on the nuclear bag and nuclear chain fibers. If the muscle tension is too great (e.g., overstretching of muscle or too heavy a load), activation of the Golgi tendon organ causes a reflex relaxation of the muscle. ©78 NEUROPHYSIOLOGY FIGURE 2.27 PROPRIOCEPTIVE REFLEX CONTROL OF MUSCLE TENSION• Interaction of the muscle spindle and Golgi tendon organ during passive stretch of a muscle (panel A) and during a contraction (panels B and C). Alpha and gamma activation from brain Alpha activation from brain Inhibitory interneuron Golgi tendon organ Golgi tendon organ Golgi tendon organ Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons Gamma motor neurons Ib fibers Ia fibers Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons Gamma motor neurons Ib fibers Ia fibers Extrafusal muscle fiber Intrafusal muscle fiber Alpha motor neurons Gamma motor neurons Ib fibers Ia fibers A. Passive stretch. Both intrafusal and extrafusal muscle fibers stretched; spindles activated. Reflex via Ia fibers and alpha motor neurons causes secondary contraction (basis of stretch reflexes, such as knee jerk). Stretch is too weak to activate Golgi tendon organs B. Active contraction. Central excitation of alpha motor neurons only causes contraction of extrafusal muscle fibers with consequent relaxation of intrafusal fibers; spindles not activated. Tension is low; does not adjust to increased resistance. Tendon organ activated, causing relaxation C. Active contraction with gamma coactivation. Intrafusal as well as extrafusal fibers contract; spindles activated, reinforcing contraction stimulus via Ia fibers in accord with resistance. Tendon organ activated, causing relaxation if load is too great Proprioception and Reflex Pathways: III ©79 NEUROPHYSIOLOGY Proprioception and Reflex Pathways: IV FIGURE 2.28 SPINAL REFLEX PATHWAYS• Summary of the spinal reflex pathways. Nociceptive fibers Ipsilateral flexion Inhibitory synapse Excitatory synapse Excitatory synapse Inhibitory synapse To extensors To flexors To extensors To flexors A. Afferent inhibition B. Stretch reflex (reciprocal inhibition) C. Recurrent inhibitionE. Flexor withdrawal reflexD. Tendon organ reflex Contralateral extension From extensor spindle receptor (Ia, II fibers) From flexor spindle (Ia, II fibers) Axoaxonic presynaptic inhibitory synapse To extensors From extensor spindle receptor (Ia, II fibers) Axosomatic or axodendritic inhibitory synapse Excitatory synapse To extensors To flexors To extensors To flexors Renshaw cells Collaterals To synergistic muscles From extensor tendon organ (Ib fibers) Inhibitory synapse Excitatory synapse ©80 NEUROPHYSIOLOGY FIGURE 2.29 SOMESTHETIC SYSTEM OF THE BODY• Pain, temperature, and pressure sensations below the head ultimattel are conveyed to the primary somatosensory cortex (postcenntra gyrus) by the anterolateral system (spinothalamic and spinoretiicula tracts). The fasciculus gracilis and cuneatus of the spinal lemniscal system convey proprioceptive, vibratory, and tactile sensattion 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. Cerebral cortex: postcentral gyrus Posterior limb of internal capsule Ventral posterolateral (VPL) nucleus of thalamus Medial lemniscus Gracile nucleus Cuneate nucleus Fasciculus gracilis Fasciculus cuneatus Dorsal (posterior) spinal root ganglion Proprioception, position Large myelinated fibers Touch, pressure, vibration Pain, temperature Small myelinated and unmyelinatte fibers Lateral cervical nucleus Spinocervical tract Lumbar part of spinal cord Ventral (anterior) spinothalamic tract: touch, pressure Lateral spinothalamic tract: pain, temperature Cervical part of spinal cord Reticular formation Lower part of medulla oblongata Spinothalamic tract Mesencephalon (cerebral peduncles) Sensory Pathways: I ©81 NEUROPHYSIOLOGY 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 trigeminna (CN V) nerve (blue and red lines in figure). Neuronal cell bodiie mediating proprioception reside in the mesencephalic nucleus of CN V (purple fibers). Most relay neurons project to the contralaatera VPM nucleus of the thalamus and thence to the postcentrra gyrus of the cerebral cortex, where they are somatotopically represented. Sensory Pathways: II Facial (VII) n. Vagus (X) n. Dorsolateral fasciculus (of Lissauer) Substantia gelatinosa (Iamina II) Cervical part of spinal cord Spinal trigeminal nucleus Spinal trigeminal tract Medullary reticular formation Pons Dorsal trigeminal lemniscus Trigeminal mesencephalic nucleus Trigeminal motor nucleus Principal sensory trigeminal nucleus Touch, pressure Pain, temperature Proprioception Trigeminal (semilunar) ganglion Ophthalmic n. Maxillary n. Sensory root and Motor root of mandibular n. Pontine reticular formation Ventral trigeminal lemniscus Midbrain (cerebral peduncles) Cerebral cortex: postcentral gyrus Ventral posteromedial (VPM) nucleus of thalamus Internal capsule ©82 NEUROPHYSIOLOGY FIGURE 2.31 DERMATOMES• Sensory information below the head is localized to specific areas of the body, which reflect the distribution of peripheral sensory fibers that convey sensations to the spinal cord through the dorsal roots (sensory nerve cell bodies reside in the corresponding dorsal root ganglion). The area of skin subserved by afferent fibers of one dorsal root is called a dermatome. This figure shows the dermattom segments and lists key dermatome levels used by cliniciaans Variability and overlap occur, so all dermatome segments are only approximations. Levels of principal dermatomes C5 C5, 6, 7 C8, T1 C6 C6, 7, 8 C8 T4 Clavicles Lateral parts of upper limbs Medial sides of upper limbs Thumb Hand Ring and little fingers Level of nipples 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 PerineumC7C8 C2 C3 C4 C5 C6 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S1 S1S2S2 S2 S1 L4 L4 L5 L5 S1 L4 S1 S3 C8 C8 C5 C6 C6 C2 C3 C4C5 T1C8 C7 C7 C7 C6 S4 S5L5 L1 L1 L2 S2, 3 L3L4 L5 L2L3 Schematic demarcation of dermatomes shown as distinct segments. There is actually considerable overlap between any two adjacent dermatomes Sensory Pathways: III ©83 NEUROPHYSIOLOGY FIGURE 2.32 VISUAL RECEPTORS• The rods and cones of the retina transduce light into electrical signaals As illustrated for the rod, light is absorbed by rhodopsin, and through the second messenger cGMP (not shown), Nachannels 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 depolarizaatio of the receptor cell membrane. Visual System: Receptors Photons of light Lumirhodopsin Metarhodopsin Retinene + Opsin Vitamin A Rhodopsin Metabolic energy Retinene + Opsin Vitamin A Circulation A. Eyeball Suspensory ligament Iris Lens CorneaCiliary body Retina Choroid Sclera Fovea Optic nerve Ora serrataAnterior chamber Posterior chamber containing aqueous humor Vitreous humor Inner limiting membrane Ganglion cell Amacrine cell Bipolar cell Horizontal cell Rod Cone Pigment cells of choroid Müller cell (supporting glial cell) Axons at surface of retina passing via optic nerve, chiasm, and tract to lateral geniculate body B. Section through retina Synaptic ending fully polarized Synaptic bar Nucleus Centriole (basal body) Na+ permeability decreased Synaptic ending depolarized Current flow Na+ permeability increased C. Rod in dark D. Rod in light ©84 NEUROPHYSIOLOGY FIGURE 2.33 RETINOGENICULOSTRIATE VISUAL PATHWAY• The retina has two types of photoreceptors: cones that mediate color vision and rods that mediate light perception but with low acuity. The greatest acuity is found in the region of the macula of the retina, where only cones are found (upper left panel). Visual signals are conveyed by the ganglion cells whose axons course in the optic nerves. Visual signals from the nasal retina cross in the optic chiasm while information from the temporal retina remains in the ipsilateral optic tract. Fibers synapse in the lateral geniculate nucleus (visual field is topographically represented here and inverted), and signals are conveyed to the visual cortex on the medial surface of the occipital lobe. Visual System: Visual Pathway Overlapping visual fields Projection on left retina Projection on right retina Central darker circle represents macular zone Lightest shades represent monocular fields Each quadrant a different color Calcarine fissure Projection on left occipital lobe Projection on right occipital lobe Projection on left dorsal lateral geniculate nucleus Projection on right dorsal lateral geniculate nucleus Lateral geniculate bodies Choroid Choroid Periphery Structure of retina (schematic): ABCGHPR G G AH HR RC C P P A B B Amacrine cells Bipolar cells Cones Ganglion cells Horizontal cells Pigment cells Rods Macula Optic tracts Optic chiasm Optic (II) nerves ©85 NEUROPHYSIOLOGY 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. Auditory System: Cochlea Utricle Saccule Semicircular canals Cochlear nerve Oval window and stapes Round window A. Membranous labyrinth within bony labyrinth (path of sound waves) B. Section through turn of cochlea Spiral ganglion Afferent nerve fibers Efferent nerve fibers Scala vestibuli Cochlear duct (scala media) Scala tympaniScala vestibuli (perilymph); weakly positive +80 mV Scala tympani (perilymph); 0 mV Vestibular (Reissner’s) membrane Cochlear duct (scala media; endolymph) Tectorial membrane Spiral ligament Bone Outer hair cells; 60 mV Basilar membrane Inner hair cell; 60 mV As basilar membrane moves up, hairs are deflected outward, causing depolarization of hair cells and increased firing of afferent nerve fibers C. Spiral organ of Corti Hair cells Inner Outer Tectorial membrane Stereocilia Basilar membrane Supporting cells Afferent nerve fibers Efferent nerve fibers Spiral lamina Spiral ganglion Rods and tunnel of Corti ©86 NEUROPHYSIOLOGY FIGURE 2.35 AUDITORY PATHWAYS• The cochlea transduces sound into electrical signals. Axons convey these signals to the dorsal and ventral cochlear nuclei, where it is tonotopically organized. Following a series of integrated relay pathways, the ascending pathway projects to the thalamus (medial geniculate bodies) and then the acoustic cortex in the transverse gyrus of the temporal lobe, where information is tonotopically represeente (low, middle, and high tones). Auditory System: Pathways Brachium of inferior colliculus Inferior colliculus Midbrain Lateral lemnisci Medulla oblongata Nuclei of lateral lemnisci Acoustic area of temporal lobe cortex Medial geniculate body Dorsal cochlear nucleus Inferior cerebellar peduncle Ventral cochlear nucleus Cochlear division of vestibulocochlear nerve Spiral ganglion Dorsal acoustic stria Reticular formation Trapezoid body Intermediate acoustic stria Correspondence between cochlea and acoustic area of cortex: Low tones Middle tones High tones Superior olivary complex Hair cells Inner Outer ©87 NEUROPHYSIOLOGY 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. Vestibular System: Receptors Vestibular ganglion Vestibular and cochlear divisions of vestibulocochlear n. Maculae Saccule Utricle Cochlear duct (scala media) B. Section of crista Opposite wall of ampulla Gelatinous cupula Hair tufts Hair cells Nerve fibers Basement membrane Superior semicirccula canal Cristae within ampullae Horizontal semicirccula canal Posterior semicirccula canal A. Membranous labyrinth C. Section of macula Otoconia Gelatinous otolithic membrane Hair tuft Hair cells Supporting cells Basement membrane Nerve fibers Hair cell (type II) Supporting cell Efferent nerve endings Afferent nerve endings Myelin sheath D. Structure and innervation of hair cells Hair cell (type I) Supporting cells Afferent nerve calyx Efferent nerve ending Basement membrane Myelin sheath Kinocilium Stereocilia Cuticle Excitation Inhibition Basal body Cuticle Kinocilium Stereocilia Basal body ©88 NEUROPHYSIOLOGY Vestibular System: Vestibulospinal Tracts Lower limb Excitatory endings Inhibitory endings Ascending fibers in medial longitudinal fasciculi Motor neuron (controlling neck muscles) Medial vestibulospiina fibers in medial longitudinal fasciculi Excitatory endings to back muscles Lower part of cervical spinal cord To axial muscles Inhibitory ending Lumbar part of spinal cord Medial Lateral Superior Vestibular nuclei Inferior To cerebellum Vestibular ganglion and nerve Fibers from cristae (rotational stimuli) Fibers from maculae (gravitational stimuli) Lateral vestibulospinal tract Excitatory interneuron Inhibitory interneuron To flexor muscles To extensor muscles Inhibitory ending ? ? ? ? To axial muscles Excitatory ending Lateral vestibulospinal tract Inhibitory interneuron Excitatory synapse To flexor muscles To extensor muscles Somatotopical pattern in lateral vestibular nucleus Rostral Caudal Trunk Upper limb Ventral Dorsal FIGURE 2.37 VESTIBULOSPINAL TRACTS• Sensory input from the vestibular apparatus is used to maintain stabillit of the head and to maintain balance and posture. Axons convve vestibular information to the vestibular nuclei in the pons, and then secondary axons distribute this information to five sites: spinal cord (muscle control), cerebellum (vermis), reticular formation (vomiting center), extraocular muscles, and cortex (conscious percepttion) This figure shows only the spinal cord pathways. ©89 NEUROPHYSIOLOGY Gustatory (Taste) System: Receptors D. Detail of taste pore E. Detail of base of receptor cells A. Tongue Foliate papillae Fungiform papillae Vallate papillae B. Section through vallate papilla Taste buds Duct of gustatory (Ebner’s) gland C. Taste bud Epithelium Basement membrane Nerve plexus Nerve fibers emerging from taste buds Microvilli Taste cells Taste pore Microvilli Epithelium Desmosomes Intercellular space Large nerve fiber Small nerve fiber Basement membrane Collagen Granules Large nerve fiber Fibroblast Schwann cell FIGURE 2.38 TASTE RECEPTORS• Taste buds on the tongue respond to various chemical stimuli. Taste cells, like neurons, normally have a net negative charge internally and are depolarized by stimuli, thus releasing transmitters that depolarriz 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. ©90 NEUROPHYSIOLOGY Gustatory (Taste) System: Pathways Lingual n. Otic ganglion Chorda tympani Fungiform papillae Foliate papillae Valiate papillae Epiglottis Larynx Superior laryngeal n. Mesencephalic nucleus and Motor nucleus of trigeminal n. Pons Greater petrosal n. Geniculate ganglion Facial (VII) n. and Nervus inermedius Rostral part of nucleus of solitary tract Glossopharyngeal (IX) n. Lower part of medulla oblongata Petrosal (inferior) ganglion of glossopharyngeal n. Nodose (inferior) ganglion of vagus n. Vagus (X) n. Ventral posteromedial (VPM) nucleus of thalamus Sensory cortex (just below face area) Lateral hypothalamic area Amygdala Pontine taste area Trigeminal (V) n. Maxillary n. Mandibular n. Pterygopalaatin ganglion 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. ©91 NEUROPHYSIOLOGY Olfactory System: Receptors Olfactory bulb Lateral nasal wall Septum A. Distribution of olfactory epithelium (blue area) Cribriform plate of ethmoid bone 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 B. Schema of section through olfactory mucosa FIGURE 2.40 OLFACTORY RECEPTORS• The sensory cells that make up the olfactory epithelium respond to odorants by depolarizing. Like taste buds, an olfactory cell can respond to more than one odorant. There are six general odor qualities that can be sensed: floral, ethereal (e.g., pears), musky, camphor (e.g., eucalyptus), putrid, and pungent (e.g., vinegar, peppermmint) ©92 NEUROPHYSIOLOGY Olfactory System: Pathway 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 circuiitr shown in upper left panel). Integrated signals pass along the olfactory tract and centrally diverge to pass to the anterior commissuur (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. Fibers from contralateral olfactory bulb Fibers to contralateral olfactory bulb Anterior commissure Medial olfactory stria Anterior perforated substance Lateral olfactory stria Lateral olfactory tract nucleus Piriform lobe Uncus Amygdala (in phantom) Entorhinal area Efferent fibers Afferent fibers Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process Tufted cell Periglomeruula cell Glomerulus Olfactory nerve fibers Olfactory epithelium Olfactory tract Olfactory nerves Anterior olfactory nucleus Olfactory bulb Cribriform plate of ethmoid bone Olfactory trigone and olfactory tubercle ©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. 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