Atlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations Illustrations by Frank H Netter, MD John A Craig, MD James Perkins, MS, MFA Text by John T Hansen, PhD Bruce M Koeppen, MD, PhD Atlas of Neuroanatomy and Neurophysiology Selections from the Netter Collection of Medical Illustrations Copyright ©2002 Icon Custom Communications All rights reserved The contents of this book may not be reproduced in any form without written authorization from Icon Custom Communications Requests for permission should be addressed to Permissions Department, Icon Custom Communications, 295 North St., Teterboro NJ 07608, or can be made at www Netterart.com NOTICE Every effort has been taken to confirm the accuracy of the information presented Neither the publisher nor the authors can be held responsible for errors or for any consequences arising from the use of the information contained herein, and make no warranty, expressed or implied, with respect to the contents of the publication Printed in U.S.A Foreword Frank Netter: The Physician, The Artist, The Art This selection of the art of Dr Frank H Netter on neuroanatomy and neurophysiology is drawn from the Atlas of Human Anatomy and Netter’s Atlas of Human Physiology Viewing these pictures again prompts reflection on Dr Netter’s work and his roles as physician and artist Frank H Netter was born in 1906 in New York City He pursued his artistic muse at the Sorbonne, the Art Student’s League, and the National Academy of Design before entering medical school at New York University, where he received his M.D degree in 1931 During his student years, Dr Netter’s notebook sketches attracted the attention of the medical faculty and other physicians, allowing him to augment his income by illustrating articles and textbooks He continued illustrating as a sideline after establishing a surgical practice in 1933, but ultimately opted to give up his practice in favor of a full-time commitment to art After service in the United States Army during the Second World War, Dr Netter began his long collaboration with the CIBA Pharmaceutical Company (now Novartis Pharmaceuticals) This 45-year partnership resulted in the production of the extraordinary collection of medical art so familiar to physicians and other medical professionals worldwide When Dr Netter’s work is discussed, attention is focused primarily on Netter the artist and only secondarily on Netter the physician As a student of Dr Netter’s work for more than forty years, I can say that the true strength of a Netter illustration was always established well before brush was laid to paper In that respect each plate is more of an intellectual than an artistic or aesthetic exercise It is easy to appreciate the aesthetic qualities of Dr Netter’s work, but to overlook its intellectual qualities is to miss the real strength and intent of the art This intellectual process requires thorough understanding of the topic, as Dr Netter wrote: “Strange as it may seem, the hardest part of making a medical picture is not the drawing at all It is the planning, the conception, the determination of point of view and the approach which will best clarify the subject which takes the most effort.” Years before the inception of “the integrated curriculum,” Netter the physician realized that a good medical illustration can include clinical information and physiologic functions as well as anatomy In pursuit of this principle Dr Netter often integrates pertinent basic and clinical science elements in his anatomic interpretations Although he was chided for this heresy by a prominent European anatomy professor, many generations of students training to be physicians rather than anatomists have appreciated Dr Netter’s concept The integration of physiology and clinical medicine with anatomy has led Dr Netter to another, more subtle, choice in his art Many texts and atlases published during the period of Dr Netter’s career depict anatomy clearly based on cadaver specimens with renderings of shrunken and shriveled tissues and organs Netter the physician chose to render “live” versions of these structures—not shriveled, colorless, formaldehyde-soaked tissues, but plump, robust organs, glowing with color! The value of Dr Netter’s approach is clearly demonstrated by the plates in this selection John A Craig, MD Austin, Texas This volume brings together two distinct but related aspects of the work of Frank H Netter, MD, and associated artists Netter is best known as the creator of the Atlas of Human Anatomy, a comprehensive textbook of gross anatomy that has become the standard atlas for students of the subject But Netter’s work included far more than anatomical art In the pages of Clinical Symposia, a series of monographs published over a period of more than 50 years, and in The Netter Collection of Medical Illustrations, this premier medical artist created superb illustrations of biological and physiological processes, disease pathology, clinical presentations, and medical procedures As a service to the medical community, Novartis Pharmaceuticals has commissioned this special edition of Netter’s work, which includes his beautiful and instructive illustrations of nervous system anatomy as well as his depictions of neurophysiological concepts and functions We hope that readers will find Dr Netter’s renderings of neurological form and function interesting and useful Click any title below to link to that plate Part Neuroanatomy Cerebrum—Medial Views Cerebrum—Inferior View Basal Nuclei (Ganglia) Thalamus Cerebellum Brainstem Fourth Ventricle and Cerebellum Accessory Nerve (XI) Arteries to Brain and Meninges 10 Arteries to Brain: Schema 11 Oculomotor (III), Trochlear (IV) and Abducent (VI) Nerves: Schema 27 Trigeminal Nerve (V): Schema 28 Facial Nerve (VII): Schema 29 Vestibulocochlear Nerve (VIII): Schema 30 Glossopharyngeal Nerve (IX): Schema 31 Vagus Nerve (X): Schema 32 Accessory Nerve (XI): Schema 33 Hypoglossal Nerve (XII): Schema 34 Nerves of Heart 35 Arteries of Brain: Inferior Views 12 Autonomic Nerves and Ganglia of Abdomen 36 Cerebral Arterial Circle (Willis) 13 Nerves of Stomach and Duodenum 37 Arteries of Brain: Frontal View and Section 14 Nerves of Stomach and Duodenum (continued) 38 Arteries of Brain: Lateral and Medial Views 15 Nerves of Small Intestine 39 Arteries of Posterior Cranial Fossa 16 Nerves of Large Intestine 40 Veins of Posterior Cranial Fossa 17 Deep Veins of Brain 18 Nerves of Kidneys, Ureters and Urinary Bladder 41 Subependymal Veins of Brain 19 Nerves of Pelvic Viscera: Male 42 Hypothalamus and Hypophysis 20 Nerves of Pelvic Viscera: Female 43 Arteries and Veins of Hypothalamus and Hypophysis 21 Median Nerve 44 Relation of Spinal Nerve Roots to Vertebrae 22 Radial Nerve in Arm and Nerves of Posterior Shoulder 46 Autonomic Nervous System: General Topography 23 Spinal Nerve Origin: Cross Sections 24 Olfactory Nerve (I): Schema 25 Optic Nerve (II) (Visual Pathway): Schema 26 Ulnar Nerve 45 Radial Nerve in Forearm 47 Sciatic Nerve and Posterior Cutaneous Nerve of Thigh 48 Tibial Nerve 49 Common Fibular (Peroneal) Nerve 50 NEUROANATOMY Sagittal section of brain in situ Cingulate gyrus Cingulate sulcus Medial frontal gyrus Sulcus of corpus callosum Fornix Septum pellucidum Interventricular foramen (Monro) Interthalamic adhesion Thalamus and 3rd ventricle Subcallosal (parolfactory) area Anterior commissure Subcallosal gyrus Hypothalamic sulcus Lamina terminalis Supraoptic recess Optic chiasm Tuber cinereum Hypophysis (pituitary gland) Mammillary body Cerebral peduncle Pons Medial surface of cerebral hemisphere: brainstem excised Cingulate gyrus Mammillothalamic fasciculus Mammillary body Cerebrum: Medial Views Paracentral sulcus Central sulcus (Rolando) Paracentral lobule Marginal sulcus Corpus callosum Precuneus Superior sagittal sinus Choroid plexus of 3rd ventricle Stria medullaris of thalamus Parietooccipital sulcus Cuneus Habenular commissure Pineal body Posterior commissure Calcarine sulcus Straight sinus in tentorium cerebelli Cerebral aqueduct (Sylvius) Great cerebral vein (Galen) Superior colliculus Inferior colliculus Tectal (quadrigeminal) plate Cerebellum Superior medullary velum 4th ventricle and choroid plexus Inferior medullary velum Medulla oblongata Genu Rostrum Trunk Splenium of corpus callosum Isthmus of cingulate gyrus Parietooccipital sulcus Cuneus Uncus Calcarine sulcus Optic nerve (II) Lingual gyrus Olfactory tract Crus Body Column Collateral sulcus Rhinal sulcus Medial occipitotemporal gyrus Occipitotemporal sulcus Lateral occipitotemporal gyrus of fornix Fimbria of hippocampus Dentate gyrus Parahippocampal gyrus NEUROANATOMY Cerebrum: Inferior View Sectioned brainstem Frontal pole of cerebrum Straight gyrus Olfactory sulcus Orbital sulci Longitudinal cerebral fissure Genu of corpus callosum Lamina terminalis Olfactory bulb Olfactory tract Orbital gyri Optic chiasm Temporal pole Optic nerve (II) (cut) Lateral sulcus (Sylvius) Hypophysis (pituitary gland) Inferior temporal sulcus Inferior temporal gyrus Anterior perforated substance Optic tract Tuber cinereum Mammillary body Inferior (inferolateral) margin of cerebrum Posterior perforated substance (in interpeduncular fossa) Rhinal sulcus Cerebral crus Uncus Lateral geniculate body Inferior temporal gyrus Substantia nigra Medial geniculate body Occipitotemporal sulcus Red nucleus Lateral occipitotemporal gyrus Pulvinar of thalamus Superior colliculus (of corpora quadrigemina) Collateral sulcus Cerebral aqueduct Parahippocampal gyrus Splenium of corpus callosum Medial occipitotemporal gyrus Calcarine sulcus Apex of cuneus Occipital pole of cerebrum Longitudinal cerebral fissure Isthmus of cingulate gyrus NEUROANATOMY Horizontal sections through cerebrum Basal Nuclei (Ganglia) A B Genu of corpus callosum Head of caudate nucleus Lateral ventricle Anterior limb of internal capsule Genu Septum pellucidum Posterior limb Column of fornix Putamen Globus pallidus Insula (island of Reil) Lentiform nucleus 3rd ventricle Interthalamic adhesion External capsule Thalamus Claustrum Crus of fornix Retrolenticular part of internal capsule Choroid plexus of lateral ventricle Tail of caudate nucleus Hippocampus and fimbria Splenium of corpus callosum Occipital (posterior) horn of lateral ventricle Habenula Organization of basal nuclei (ganglia) A B Caudate Putamen Globus nucleus pallidus Striatum Lentiform nucleus Corpus striatum Basal nuclei (ganglia) Pineal body Cleft for internal capsule Caudate nucleus Levels of sections above Body Head A B Thalamus A B Pulvinar Lentiform nucleus (globus pallidus medial to putamen) Amygdaloid body Medial geniculate body Lateral geniculate body Tail of caudate nucleus Interrelationship of thalamus, lentiform nucleus, caudate nucleus and amygdaloid body (schema): left lateral view NEUROANATOMY Thalamus Corpus callosum (cut) Interventricular foramen (Monro) Head of caudate nucleus Tela choroidea (cut edge) of 3rd ventricle Septum pellucidum 3rd ventricle Columns of fornix Choroid plexus Anterior tubercle Superior thalamostriate vein Stria terminalis Pes hippocampi Interthalamic adhesion Temporal (inferior) horn of lateral ventricle Lamina affixa Internal cerebral vein Stria medullaris Dentate gyrus Habenular trigone Collateral eminence Pulvinar (retracted) Hippocampus Lateral geniculate body Fimbria of hippocampus Medial geniculate body Posterior commissure Brachium of superior colliculus Habenular commissure Brachium of inferior colliculus Pineal body Collateral trigone Superior colliculus Calcar avis Inferior colliculus Occipital (posterior) horn of lateral ventricle Cerebellum Calcarine sulcus 3rd ventricle Internal medullary lamina Interthalamic adhesion a Pulvinar rio r MD LP M Intralaminar nuclei Inte LP 3rd ventricle VPL M External medullary lamina VP Median nuclei Schematic section through thalamus (at level of broken line shown in figure at right) Thalamic nuclei CM LD LP M MD VA VI VL VP VPL VPM Centromedian Lateral dorsal Lateral posterior Medial Medial dorsal Ventral anterior Ventral intermedial Ventral lateral Ventral posterior Ventral posterolateral Ventral posteromedial VL VP Reticular nucleus VP CM rn L VA La m in n te An dia Me ial d na Me llar y lami u d D e L al m VP M VI Pulvinar Lateral geniculate body Medial geniculate body Schematic representation of thalamus (external medullary lamina and reticular nuclei removed) Lateral nuclei Medial nuclei Anterior nuclei NEUROPHYSIOLOGY Proprioception and Reflex Pathways: IV B Stretch reflex (reciprocal inhibition) A Afferent inhibition From extensor spindle receptor (Ia, II fibers) From extensor spindle receptor (Ia, II fibers) From flexor spindle (Ia, II fibers) Axosomatic or axodendritic inhibitory synapse Axoaxonic presynaptic inhibitory synapse Excitatory synapse To extensors To extensors To flexors C Recurrent inhibition D Tendon organ reflex From extensor tendon organ (Ib fibers) Inhibitory synapse Renshaw cells Excitatory synapse Collaterals To extensors To synergistic muscles To flexors E Flexor withdrawal reflex Nociceptive fibers Ipsilateral flexion Contralateral extension Inhibitory synapse Excitatory synapse Excitatory synapse Inhibitory synapse To extensors To flexors To extensors To flexors â FIGURE 2.28 SPINAL REFLEX PATHWAYSã Summary of the spinal reflex pathways 79 NEUROPHYSIOLOGY Sensory Pathways: I Cerebral cortex: postcentral gyrus Posterior limb of internal capsule Ventral posterolateral (VPL) nucleus of thalamus Mesencephalon (cerebral peduncles) Medial lemniscus Gracile nucleus Spinothalamic tract Cuneate nucleus Lower part of medulla oblongata Fasciculus gracilis Fasciculus cuneatus Reticular formation Dorsal (posterior) spinal root ganglion Proprioception, position Cervical part of spinal cord Touch, pressure, vibration Lateral spinothalamic tract: pain, temperature Pain, temperature Spinocervical tract Lumbar part of spinal cord â OF THE BODYã Pain, temperature, and pressure sensations below the head ultimately are conveyed to the primary somatosensory cortex (postcentral gyrus) by the anterolateral system (spinothalamic and spinoreticular tracts) The fasciculus gracilis and cuneatus of the spinal lemniscal system convey proprioceptive, vibratory, and tactile sen- 80 Small myelinated and unmyelinated fibers Lateral cervical nucleus Ventral (anterior) spinothalamic tract: touch, pressure FIGURE 2.29 SOMESTHETIC SYSTEM Large myelinated fibers sations to the thalamus (ventral posterolateral nucleus), whereas the lateral cervical system mediates some touch, vibratory, and proprioceptive sensations (blue and purple lines show these dual pathways) Ultimately, these fibers ascend as parallel pathways to the thalamus, synapse, and ascend to the cortex NEUROPHYSIOLOGY Sensory Pathways: II Cerebral cortex: postcentral gyrus Ventral posteromedial (VPM) nucleus of thalamus Internal capsule Midbrain (cerebral peduncles) Dorsal trigeminal lemniscus Trigeminal mesencephalic nucleus Trigeminal motor nucleus Principal sensory trigeminal nucleus Touch, pressure Pain, temperature Proprioception Ventral trigeminal lemniscus Pontine reticular formation Trigeminal (semilunar) ganglion Ophthalmic n Maxillary n Pons Sensory root and Motor root of mandibular n Medullary reticular formation Spinal trigeminal tract Spinal trigeminal nucleus Cervical part of spinal cord Facial (VII) n Vagus (X) n Dorsolateral fasciculus (of Lissauer) Substantia gelatinosa (Iamina II) FIGURE 2.30 SOMESTHETIC SYSTEM OF THE â HEADã Nerve cells bodies for touch, pressure, pain, and temperature in the head are in the trigeminal (semilunar) ganglion of the trigeminal (CN V) nerve (blue and red lines in figure) Neuronal cell bodies mediating proprioception reside in the mesencephalic nucleus of CN V (purple fibers) Most relay neurons project to the contralateral VPM nucleus of the thalamus and thence to the postcentral gyrus of the cerebral cortex, where they are somatotopically represented 81 NEUROPHYSIOLOGY Sensory Pathways: III Schematic demarcation of dermatomes shown as distinct segments There is actually considerable overlap between any two adjacent dermatomes C2 C3 C4 C5 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 C2 C3 C4 C5 C6 C7 C8 C6 C6 T1 C5 C8 C7 C6 C8 C7 C7 S2, L2 C8 S3 S4 S5 L3 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S1 S2 S1 S2 L5 L1 L4 L2 L3 L5 S1 S2 L4 S1 S1 L5 L5 L4 L4 Levels of principal dermatomes Clavicles C5 C5, 6, Lateral parts of upper limbs Medial sides of upper limbs C8, T1 Thumb C6 C6, 7, Hand Ring and little fingers C8 Level of nipples T4 T10 T12 L1, 2, 3, L4, 5, S1 L4 S1, 2, L5 S1 S2, 3, Level of umbilicus Inguinal or groin regions Anterior and inner surfaces of lower limbs Foot Medial side of great toe Posterior and outer surfaces of lower limbs Lateral margin of foot and little toe Perineum â FIGURE 2.31 DERMATOMESã Sensory information below the head is localized to specific areas of the body, which reflect the distribution of peripheral sensory fibers that convey sensations to the spinal cord through the dorsal roots (sensory nerve cell bodies reside in the corresponding dorsal root ganglion) The area of skin subserved by afferent fibers of one 82 dorsal root is called a dermatome This figure shows the dermatome segments and lists key dermatome levels used by clinicians Variability and overlap occur, so all dermatome segments are only approximations NEUROPHYSIOLOGY Visual System: Receptors B Section through retina A Eyeball Iris Lens Axons at surface of retina passing via optic nerve, chiasm, and tract to lateral geniculate body Cornea Suspensory ligament Ciliary body Anterior chamber Inner limiting membrane Ganglion cell Posterior chamber Müller cell (supporting glial cell) Amacrine cell Bipolar cell Horizontal cell Rod Cone Pigment cells of choroid Ora containing serrata aqueous humor Vitreous humor Retina Choroid Sclera Fovea Optic nerve Synaptic ending fully polarized Synaptic ending depolarized C Rod in dark D Rod in light Photons of light Rhodopsin Metabolic energy Current flow Na+ permeability increased Retinene + Opsin Vitamin A Synaptic bar Nucleus Lumirhodopsin Metarhodopsin Retinene + Opsin Vitamin A Centriole (basal body) Na+ permeability decreased Circulation â FIGURE 2.32 VISUAL RECEPTORSã The rods and cones of the retina transduce light into electrical signals As illustrated for the rod, light is absorbed by rhodopsin, and through the second messenger cGMP (not shown), Na⫹ channels in the membrane close and the cell hyperpolarizes Thus, in the dark the cell is depolarized, but it is hyperpolarized in the light This electrical response to light is distinct from other receptor responses, in which the response to a stimulus results in a depolarization of the receptor cell membrane 83 NEUROPHYSIOLOGY Visual System: Visual Pathway Central darker circle represents macular zone G G Overlapping visual fields A Lightest shades represent monocular fields A B B H H Each quadrant a different color R RC P Choroid C Projection on left retina Projection on right retina Optic (II) nerves Optic chiasm P Choroid Periphery Macula Structure of retina (schematic): Projection on left A Amacrine cells dorsal lateral B Bipolar cells geniculate nucleus C Cones G Ganglion cells H Horizontal cells P Pigment cells R Rods Optic tracts Projection on right dorsal lateral geniculate nucleus Lateral geniculate bodies Calcarine fissure Projection on left occipital lobe Projection on right occipital lobe © FIGURE 2.33 RETINOGENICULOSTRIATE VISUAL PATHWAY• The retina has two types of photoreceptors: cones that mediate color vision and rods that mediate light perception but with low acuity The greatest acuity is found in the region of the macula of the retina, where only cones are found (upper left panel) Visual signals are conveyed by the ganglion cells whose axons course in the optic nerves Visual signals from the nasal retina cross in the 84 optic chiasm while information from the temporal retina remains in the ipsilateral optic tract Fibers synapse in the lateral geniculate nucleus (visual field is topographically represented here and inverted), and signals are conveyed to the visual cortex on the medial surface of the occipital lobe NEUROPHYSIOLOGY Auditory System: Cochlea Cochlear nerve A Membranous labyrinth within bony labyrinth (path of sound waves) Semicircular canals Utricle Saccule Scala vestibuli Cochlear duct (scala media) Scala tympani B Section through turn of cochlea Round window Scala vestibuli (perilymph); weakly +80 mV positive Efferent nerve fibers Oval window and stapes Vestibular (Reissner’s) membrane Cochlear duct (scala media; endolymph) Tectorial membrane Spiral ligament Bone Outer hair cells; ⫺60 mV Scala tympani (perilymph); mV Afferent nerve fibers Basilar membrane Spiral ganglion C Spiral organ of Corti Inner hair cell; ⫺60 mV Hair cells Inner Outer Tectorial membrane Stereocilia Rods and tunnel of Corti Basilar membrane Supporting cells Afferent nerve fibers Spiral lamina Spiral ganglion Efferent nerve fibers As basilar membrane moves up, hairs are deflected outward, causing depolarization of hair cells and increased firing of afferent nerve fibers © FIGURE 2.34 COCHLEAR RECEPTORS• The cochlea transduces sound into electrical signals This is accomplished by the hair cells, which depolarize in response to vibration of the basilar membrane The basilar membrane moves in response to pressure changes imparted on the oval window of the cochlea in response to vibrations of the tympanic membrane 85 NEUROPHYSIOLOGY Auditory System: Pathways Acoustic area of temporal lobe cortex Medial geniculate body Brachium of inferior colliculus Inferior colliculus Midbrain Lateral lemnisci Nuclei of lateral lemnisci Medulla oblongata Correspondence between cochlea and acoustic area of cortex: Low tones Middle tones High tones Dorsal cochlear nucleus Inferior cerebellar peduncle Ventral cochlear nucleus Cochlear division of vestibulocochlear nerve Dorsal acoustic stria Reticular formation Trapezoid body Intermediate acoustic stria Superior olivary complex Inner Outer Spiral ganglion Hair cells © FIGURE 2.35 AUDITORY PATHWAYS• The cochlea transduces sound into electrical signals Axons convey these signals to the dorsal and ventral cochlear nuclei, where it is tonotopically organized Following a series of integrated relay pathways, the ascending pathway projects to the thalamus (medial 86 geniculate bodies) and then the acoustic cortex in the transverse gyrus of the temporal lobe, where information is tonotopically represented (low, middle, and high tones) NEUROPHYSIOLOGY Vestibular System: Receptors A Membranous labyrinth Vestibular ganglion Superior semicircular canal Vestibular and cochlear divisions of vestibulocochlear n Maculae Saccule Utricle Cristae within ampullae Horizontal semicircular canal Posterior semicircular canal Cochlear duct (scala media) B Section of crista Opposite wall of ampulla Gelatinous cupula Hair tufts C Section of macula Otoconia Gelatinous otolithic membrane Hair tuft Hair cells Supporting cells Basement membrane Nerve fibers Hair cells Nerve fibers Basement membrane Excitation D Structure and innervation of hair cells Inhibition Kinocilium Kinocilium Stereocilia Basal body Cuticle Cuticle Stereocilia Basal body Hair cell (type I) Hair cell (type II) Supporting cells Supporting cell Afferent nerve calyx Efferent nerve endings Efferent nerve ending Afferent nerve endings Basement membrane Myelin sheath Myelin sheath © FIGURE 2.36 VESTIBULAR RECEPTORS• The vestibular apparatus detects movement of the head in the form of linear and angular acceleration This information is important for the control of eye movements so that the retina can be provided with a stable visual image It is also important for the control of posture The utricle and saccule respond to linear acceleration, such as the pull of gravity The three semicircular canals are aligned so that the angular movement of the head can be sensed in all planes The sensory hair cells are located in the maculae of the utricle and saccule and in the cristae within each ampullae 87 NEUROPHYSIOLOGY Vestibular System: Vestibulospinal Tracts Excitatory endings Inhibitory endings Superior Medial Lateral Inferior Ascending fibers in medial longitudinal fasciculi Vestibular nuclei Rostral Upper limb Trunk Ventral Dorsal To cerebellum Lower limb Caudal Somatotopical pattern in lateral vestibular nucleus Vestibular ganglion and nerve Motor neuron (controlling neck muscles) Medial vestibulospinal fibers in medial longitudinal fasciculi Lateral vestibulospinal tract Excitatory interneuron Excitatory endings to back muscles ? Inhibitory interneuron ? Lower part of cervical spinal cord Fibers from maculae (gravitational stimuli) To flexor muscles To extensor muscles ? To axial muscles Fibers from cristae (rotational stimuli) Inhibitory ending ? To axial muscles Inhibitory ending Lumbar part of spinal cord Excitatory ending Lateral vestibulospinal tract Inhibitory interneuron Excitatory synapse To flexor muscles To extensor muscles © FIGURE 2.37 VESTIBULOSPINAL TRACTS• Sensory input from the vestibular apparatus is used to maintain stability of the head and to maintain balance and posture Axons convey vestibular information to the vestibular nuclei in the pons, and then secondary axons distribute this information to five sites: spinal 88 cord (muscle control), cerebellum (vermis), reticular formation (vomiting center), extraocular muscles, and cortex (conscious perception) This figure shows only the spinal cord pathways NEUROPHYSIOLOGY Gustatory (Taste) System: Receptors A Tongue Foliate papillae B Section through vallate papilla Taste buds Duct of gustatory (Ebner’s) gland C Taste bud Epithelium Fungiform papillae Vallate papillae Basement membrane Nerve plexus Microvilli Taste pore Nerve fibers emerging from taste buds Taste cells Desmosomes Epithelium Large nerve fiber Fibroblast Basement membrane Granules Schwann cell Small nerve fiber Collagen Intercellular space Large nerve fiber Microvilli D Detail of taste pore E Detail of base of receptor cells © FIGURE 2.38 TASTE RECEPTORS• Taste buds on the tongue respond to various chemical stimuli Taste cells, like neurons, normally have a net negative charge internally and are depolarized by stimuli, thus releasing transmitters that depo- larize neurons connected to the taste cells A single taste bud can respond to more than one stimulus The four traditional taste qualities that are sensed are sweet, salty, sour, and bitter 89 NEUROPHYSIOLOGY Gustatory (Taste) System: Pathways Ventral posteromedial (VPM) nucleus of thalamus Sensory cortex (just below face area) Lateral hypothalamic area Amygdala Mesencephalic nucleus and Motor nucleus of trigeminal n Pontine taste area Trigeminal (V) n Maxillary n Mandibular n Pons Pterygopalatine ganglion Greater petrosal n Geniculate ganglion Facial (VII) n and Nervus inermedius Rostral part of nucleus of solitary tract Otic ganglion Lingual n Chorda tympani Glossopharyngeal (IX) n Fungiform papillae Foliate papillae Lower part of medulla oblongata Valiate papillae Petrosal (inferior) ganglion of glossopharyngeal n Nodose (inferior) ganglion of vagus n Vagus (X) n Epiglottis Larynx Superior laryngeal n © FIGURE 2.39 TASTE PATHWAYS• Depicted here are the afferent pathways leading from the taste receptors to the brainstem and, ultimately, to the sensory cortex in the postcentral gyrus 90 NEUROPHYSIOLOGY Olfactory System: Receptors Olfactory bulb Lateral nasal wall A Distribution of olfactory epithelium (blue area) Cribriform plate of ethmoid bone Septum B Schema of section through olfactory mucosa Cribriform plate Schwann cell Olfactory gland Unmyelinated olfactory axons Basement membrane Sustentacular cells Endoplasmic reticulum Nucleus Olfactory cells Dendrites Terminal bars (desmosomes) Olfactory rod (vesicle) Villi Cilia Mucus â FIGURE 2.40 OLFACTORY RECEPTORSã The sensory cells that make up the olfactory epithelium respond to odorants by depolarizing Like taste buds, an olfactory cell can respond to more than one odorant There are six general odor qualities that can be sensed: floral, ethereal (e.g., pears), musky, camphor (e.g., eucalyptus), putrid, and pungent (e.g., vinegar, peppermint) 91 NEUROPHYSIOLOGY Olfactory System: Pathway Efferent fibers Afferent fibers Granule cell (excited by and inhibiting to mitral and tufted cells) Mitral cell Recurrent process Fibers from contralateral olfactory bulb Fibers to contralateral olfactory bulb Anterior commissure Tufted cell Medial olfactory stria Periglomerular cell Olfactory trigone and olfactory tubercle Glomerulus Olfactory nerve fibers Anterior perforated substance Lateral olfactory stria Lateral olfactory tract nucleus Piriform lobe Uncus Amygdala (in phantom) Entorhinal area Olfactory epithelium Olfactory nerves Olfactory bulb Olfactory tract Anterior olfactory nucleus Cribriform plate of ethmoid bone â FIGURE 2.41 OLFACTORY PATHWAYã Olfactory stimuli are detected by the nerve fibers of the olfactory epithelium and conveyed to the olfactory bulb (detailed local circuitry shown in upper left panel) Integrated signals pass along the olfactory tract and centrally diverge to pass to the anterior commis- 92 sure (some efferent projections course to the contralateral olfactory bulb, blue lines) or terminate in the ipsilateral olfactory trigone (olfactory tubercle) Axons then project to the primary olfactory cortex (piriform cortex), entorhinal cortex, and amygdala Installing Adobe Acrobat Reader 5.0 The images and text included in this atlas are contained in a Portable Document Format (pdf) file and can be viewed with Adobe Acrobat Reader A copy of Acrobat Reader 5.0 is included on this CD You will need to install or upgrade to Acrobat Reader 5.0 in order to have full functionality Please follow these 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