UNIVERSITY OF CALIFORNIA SAN FRANCISCO LIBRARY Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/appliedanatomyofOOrannrich THE APPLIED A:NAT0MY I OF THE NERVOUS SYSTEM, BEING A STUDY OF THIS PORTION OF THE HUMAN BODY FROM A STANDPOINT OF ITS GENERAL INTEREST AND PRACTICAL UTILITY, DESIGNED FOR USE AS A TEXT-BOOK AND A WORK OF REFERENCE, BY I AMBKOSE L. KANNEY, A. M., M. D. JUNCT PROFESSOR OF ANATOMY AND LATE LECTITRKR ON THE DISEASES OP THE GENITO-TIRINAEY ORGANS AND ON MINOR SURGERY IN THE MEDICAL DEPARTMENT OF THE UNIVERSITY OP THE CITY OF NEW YORK ; LATE SURGEON TO THE NORTHERN AND NORTHWESTERN dispensaries; resident fellow of the new york academy OF medi- cine; MEMBER OF THE MEDICAL SOCIETY OF THE COUNTY OF NEW YORK; AUTHOR OF A '"PRACTICAL TREATISE ON SU^C^ICAL , PIAGNOPJe^" 'VTHP,S'-S8DK'inALS''©P ^^AWMY.^'^ETC. wiTd ifm^i.ousl22ips,f^Ah(XNis^ "The greatest thing a human soul ever does in this world is to see something, and tell what he saw in a plain way. Hundreds of people can talk for one that can think, but thousands can think tor one who can see. To see clearly is paetry, prophecy, and religion all in one." — John KusIin. NEW YORK: D. APPLETON AND COMPANY, 1, 3, AND 5 BOND STREET. 1881. % COPTBIGHT BY D. APPLETON AND COMPANY. 1881. ,.,?,•;■ TO THE FACULTY OF THE MEDICAL DEPARTMENT OF THE UNIVERSITY OF THE CITY OF NEW YORK, TJXDER THE GUIDANCE OF SOME OF WHOM I PURSUED MY. EARLY MEDICAL STUDIES, AND TO WHOSE INDUSTRY AND TALENT IS DUE MUCH OF THE SUCCESS WHICH HAS CROWNED THEIR EFFORTS AS INSTRUCTORS, THIS VOLUME IS RESPECTFULLY DEDICATED BY THE AUTHOR. " u^d PEEFACE This volume comprises a course of lectures wliicli were delivered by me before the students of tlie Medical Depart- ment of tlie University of tlie City of New York during the mnter of 1880 and 1881. They are presented to the reading public, with few alterations, as they were originally reported for some of the medical journals, and for the private use of the author. The same colloquial style in which they were delivered has been retained, since it is believed that it will thus better fill the requirements of a text-book. I am well aware that the highest type of lit- erary composition is not of this conversational character, and that it may be to some readers a drawback rather than an attractive feature in the volume ; but the fact is also recognized that the best style, theoretically, is not always the clearest and the most forcible, and that successful teachers have often to sacrifice beauty of rhetoric in order to impart their knowledge. I have departed somewhat from the custom of anatom- ical authors in making diagrammatic illustrations — ^which it is my habit to draw upon the black-board before my classes, in order to make the listener use the eye as well as the intelligence as a means of gaining information — a prom- vi PREFACE. inent feature of this volume. I have found, for some years, that the drawmg of illustrations of this character before the eyes of the student gave a much clearer perception of some obscure points than words could effect, and had a great advantage in this respect over the most elaborate and skillfully executed plates. I have, therefore, incor- porated many of my own designing, and some others which have been culled from different sources and modified to suit the demand of the moment. I have, in some instances, allowed the text to follow and explain these diagrams, as if the lecture were in actual progress, rather than to trust the descriptive text of the cuts alone to interpret their meaning. The liberality of the publishers has enabled me to fur- ther ornament the work with the beautiful cuts of Sap- pey and Hii'schfeld, some of which, to my knowledge, have never appeared in any American work, while I am indebted to my friend Professor Austin Flint, Jr., for some, culled from the same authors, which have appeared in his work upon physiology, and to my colleague and friend Professor William A. Hammond for some of the admirable photo- graphs and woodcuts in his elaborate treatise on nervous diseases. I desire also to express my indebtedness to my friend Professor E. C. Seguin for some late monogi'aphs and some excellent diagrams, and to the works of Charcot, Ferrier, Brown-Sequard, Kosenthal, Hammond, Foster, Hil- ton, Flint, and others, as well as to the authors of such valuable monographs as those of Turck, Hughlings-Jack- son, Vulpian, Pitres, Duret, Dodds, Nothnagel, Duchenne, Lockhart Clarke, Flechsig, and Erb, for the valuable as- sistance which I have derived from their labors. It has been my intention, as far as possible without disfiguring the text, to give all credit to those authors who have a PREFACE. vii just claim to priority, where the originality of any matter is discussed, and to acknowledge my indebtedness to authors for extracts in foot-notes scattered throughout the volume. The rapid strides which are being made in the inter- pretation of the symptoms of nervous diseases and the introduction of many new terms which must embarrass the reader of late treatises, unless he be educated up to the present standard of knowledge in this Held of medicine, seem to the author a reasonable ground for belief that there is a demand for a volume which shall fit the practitioner and student to pursue his studies in this special line with- out embarrassment, if not with increased interest. I have endeavored not to lose sight of the fact that the basis of the work was an anatomical one, and that, while the clinical points could be explained chiefly by anat- omy, the treatment of nervous diseases had no place in the volume. For the reason, also, that the aim of the work is of a practical character, much detail of a purely de- scriptive kind has been deemed unimportant in some in- stances ; while, again, facts which are too often slighted in descriptive treatises have been here given w^th unusual detail, as they seemed to me to suggest points of inter- est which had been overlooked or intentionally omitted by others. It is not to be expected that many points stated in the physiology, symptomatology, or even in the anatomy, will not be open to discussion, and, possibly, to contradiction. It is almost impossible, to-day, for any two disputants upon nervous affections or nervous physiology to fail to find support for either side in the literature of the subject; but the statements which this volume contains will, it is to be hoped, receive the concurrence of those most ad- vanced in this line of study. viii PREFACE. Witli what merits or demerits the volume may possess, I intrust it to the public, conscious that an effort to clear up a field made obscure by visionary theories and endless speculation can not but contain some ground to which ex- ception may be taken. To what extent it will supply the place of a guide in this — the labyrinth of medical science — experience alone must decide. Ambrose L. Rani^ey. New York City, 156 Madison Avexue, April 10, 1881. TABLE OF COI^TEISTTS. GENERAL mXRODUCTTON . . . . . 1-16 The nervous system considered as a whole. Its component parts. The general axioms of nerve distribution. PART I. THE BRAIISr ....... 16-92 Its anatomy, functions, and clinical aspects. Its general construction. Its weight, and that of its component parts. Its rapidity of growth and alterations with age. Its individual ganglia. The cerebrum ....... 25-54 Its situation and construction. Its converging and commissural fibers. Its general functions and special centers. Centers of motion ; of speecli ; of vision ; of hearing ; of touch ; of smell ; of taste. The frontal lobe. Its functions ; motor centers ; white substance. The motor area. Parts of the cerebrum comprised within it : situation of the spe- cial imotor centers; diagnosis of cortical motor paralysis; effects of irritative lesions of the motor area. The sensory area. Parts of the cerebrum comprised within it; effects of lesions within it. The occipital lobe. Its relation to vision ; psychical functions. The temporo -sphenoidal lobe. Its relation to vision; to ocular movements; to hearing; to ol- factory sense ; to taste ; to tactile sensation. The corpus striatum and optic thalamus . . . 54-58 Situation of the "basal ganglia." Functions of the "basal ganglia." TABLE OF CONTENTS. functioxs of the caudate nucleus. Functions of the lenticular nucleus. The corpora quadrigemina ..... 58-59 Their relation to vision. Their relation to ocular movements. Their relation to coohdination of movement. The crura cerebri and pons Varolii . . . 59-61 Their relation to coordination of muscular movement. Their relation to crossed paralysis. Their relation to the sensation of pain. Their probable functions. The cerebellum ...... Cl-65 Its numerous connections. Effects of lesions within its substance. Cerebellar ataxia. Its relation to hearino and sight. The medulla oblongata ..... 65-68 Its relation to cranial nerves. Its physiological centers: Kespiratoiy; salivary; vaso-niotor; diabetic; cardio-inhibitory ; for deglutition ; for vomiting ; for movements of oesophagus and stomach ; for digestive secretions. Its relations to coordination of movement. The surgical bearings of cerebral topography . . 68-74 Guides to the fissure of Rolando. Guides to the external parieto-occipital fissure. Guides to the fissure of Sylvius. Guides to the limits of the "basal ganglia." Guides to the motor centers. Guides to the center of speech. Indications and contraindications for trephining of the skull. The clinical significance of ansBsthesia after an injury to the skull ; of convulsive movements ; of the Cheyne-Stokes respiration ; of " choked disk " after an injury ; of vomiting after an injury ; of aphasia after an injury ; of monoplegia after an injury. General summary of the anatomy of the brain and ITS clinical aspects .... 74-92 Summary of its gross anatomy. The lobes of the brain. The fissures of the brain. The lobules of the brain. The gyri of each lobe. The clinical subdivisions of the brain. Symptoms referable to the base of the cerebrum ; to the basal ganglia ; to the white center of the hemispheres ; to the in- ternal capsule; to the cortex of the hemispheres; to the cere- bellum. TABLE OF CONTENTS. xi PAGES Summary of the physiology of the cerebral cortex and the effects of lesions involving it. The excitable portion (motor area) — its special centers and their action; the frontal convolutions; the parietal convolutions; the angular gyrus (probable center of vision); the superior temporosphenoidal gyrus (probable center of hearing) ; the center of speech. Clinical deductions of practical value. Types of monoplegia and the special significance of each ; con- vulsions of cerebral origin (Jacksonian epilepsy); embolism of middle cerebral artery and its effects ; clinical significance of late rigidity of paralyzed muscles ; general paralysis of the insane; lesions of the basal ganglia of the cerebrum; let-ions of the internal capsule of the cerebrum ; lesions of the white center of the hemispheres. PART II. THE CRANIAL NERVES . . . . . 93-287 Their anatomy, physiology, and clinical value. Enumeration, from before backward, as they escape from THE cavity of THE CRANIUM. The olfactory nerve ..... 95-103 Its origin and construction. ' The peculiarities of its filaments. The limits of its distribution. The physiology of olfaction. The act of sneezing. Reflex acts dependent upon the olfactory nerve. Functions of olfactory nerve in animals. Relations of the sense of smell to that of taste. Clinical points afforded by the olfactory nerve. "Hyperosmia," its tests and causes; "anosmia," its tests and causes. The optic nerve ...... 103-127 The optic tracts, their origin and attachments. The optic chiasm, its construction and physiology. Distribution of optic nerve. Reflex acts excited by optic nerve. Decussation of optic fibers and its physiology. Relations of the optic nerve in the orbit. Anatomical defects of vision and their consequences. "Hyperopia," its tests, causes, and results; "myopia," its tests, causes, and results ; "astigmatism," its tests, causes, and results. Changes observed in the pupil. Dilatation, its causes and physiology ; contraction, its causes and physiology. xii TABLE OF CONTENTS. PAGES Visual sensations and their modifications. Muscae volitantes; the ''blind spot" of the retina; insensibil- ity of the retina after firm pressure. The perception of color. Visual purple and its probable functions; rods and cones of the retina ; Young-Helinholtz theory of color vision : limits of different color perceptions ; color blindness. Apparent vision of objects not really serx. Its causes. Effects of optic jierve on coordination. Goltz's experiments. Effects of optic nerve on the lachrymal apparatus. The act of winking the eyelid ; eff'ect of closure of eyelid upon the lachrymal canals. Clinical points afforded by the optic nerve. Hemianopsia, temporal, its causes; hemianopsia, nasal, its causes; hemianopsia, bi-nasal, its causes; hemianopsia, bi- temporal, its causes; amaurosis; hypereBsthesia of the optic nerve ; amblyopia ; atrophy of optic nerve. The motor oculi nerve ..... 127-149 Its origin, course, and distribution. The physiology of contraction of the pupil. Physiological reasons for the distribution of the third nerve. Mechanism of the dilatation of the pupil. Movements of the eyeball. Diagnostic attitudes of the head in ocular paresis. Clinical points pertaining to the third nerve. Megalopsia ormacropsia; micropsia; ptosis; motor oculi pa- ralysis ; strabismus. Diseases of the ocular muscles : nystag- mus; iritic spasm; contracture; paralysis; tabetic condi- tions; diplopia; strabismus. The trochlear or pathetic nerve . . . 149-151 Its superficial and deep points of origin. Its course and relations within the cranium. Its points of clinical interest. The trigeminus nerve ..... 151-175 Its superficial and deep points of origin. Course of its sensory and motor roots within the cranium. Its afferent and efferent fibers. The effects of section of the nerve. On sensation ; on mastication ; on taste ; on bearing ; on sight ; on smell. Clinical points pertaining to the trigeminus nerve. Neuralgia (tic-douloureux) ; spasm of the trigeminus; paralysis of its individual branches. Diagnostic value of the trigeminus nerve. Bleaching of the hair ; immobility of temporo-maxillary joint ; furring of the tongue ; ulceration of the cornea; ulceration TABLE OF CONTENTS. XIU of the auditory canal ; earache ; pain in the scalp ; conjunc- tival distribution. Surgical anatomy of its maix branches. Section of the snpra-orbital nerve ; section of the supra-maxil- lary nerve; section of the inferior-dental nerve. The ganglia connected with the trigeminus nerve. Ophthalmic, lenticular, or ciliary ; spheno-palatine or Meckel's; otic; sub-maxillary. The abducens nerve (motor oculi externus) . . 175-177 Its superficial and deep points of origin. Its relation with the ophthalmic ganglion. Its clinical relations. The facial nerve ...... 177-198 Its superficial and deep points of origin. Its course and distribution. Physiology of its main branches. Tlie petrosal nerves; the chorda tympani nerve; the "pars intermedia" of Wrisberg; the tympanic branch; the facial branches ; the muscular branches. Its communications with other parts. Branches joining the fifth nerve; branch to the otic ganglion ; branch to Meckel's ganglion ; sympathetic fibers ; its rela- tion to deglutition and speech ; its relation to smell ; its re- lation to hearing ; its relation to respiration. Its filaments of distribution. Physiological relation to deglutition; physiological relation to facial expression ; physiological relation to mastication. Clinical points pertaining to the nerve. Spasm of the facial muscles. Bell's paralysis : intra-cranial va- riety ; auditory variety ; rheumatic variety ; traumatic vari- ety ; syphilitic variety ; diphtheritic variety ; facial diplegia. The auditory nerve ..... 198-220 Its superficial and deep points of origin. Anatomical structure and peculiarities of its filaments. Its course and distribution. Functions of its various branches. The mechanism of audition. External ear, its construction and functions ; middle ear, its con- struction and functions. Internal ear, its construction and functions : the semicircular canals ; the vestibule. The coch- lea : its scahie ; organ of Corti ; membranes and ligaments. Clinical points pertaining to the nerve. Auditory vertigo — " Meniere's disease " ; injuries to the semi- circular canals. Neuroses of the auditory nerve : acoustic hyperesthesia ; acoustic anaesthesia. The glosso-pharyngeal nerve . . . . 220-236 Its superficial and deep points of origin. Its ganglionic enlargements. XIV TABLE OF CONTENTS. Its course and relations. Its efferent or motor fibers. Its afferent or sensory fibers. Its fibers of taste. Effects of section of the nerve. On special sense of taste ; on deglutition. Mechanism of the act of deglutition. First period ; second period ; third period ; nerves involved ; importance of soft palate; the nerve center for the act. Clinical points pertaining to the nerve. Glosso-labio-laryngeal paralysis — Duchenne's disease ; hyper- geusia; ageusia. The pneumogastric nerve ..... 236-259 Its superficial and deep points of origin. Its intimate affiliation with the glosso- pharyngeal nerve. Its ganglionic enlargements. The inherent fibers of its trunk. Its branches of distribution and their functions. The pharyngeal branches: effects on deglutition; effects on voice. The laryngeal branches: their relation to phona- tion ; their relation to respiration ; their relation to spinal accessory nerve. The branches to alimentary canal : their relation to peristaltic action; their relation to secretion. The cardiac branches : depressor nerve of heart's action ; effects of galvanism. Yaso-motor fibers: effects on blood- vessels. The pulmonary branches : their relation to respi- ration — acceleratory fibers ; inhibitory fibers. The course and relations of the nerve on each side of THE body — "With carotid artery ; with jugular vein ; with oisophagus ; with the lungs ; with the abdominal viscera. Effects of section of the pneumogastric trunk. Upon the larynx ; upon the lungs; upon the heart. Upon the digestive tract : stomach ; liver ; intestinal canal. Clinical points pertaining to the nerve. Pharyngeal anaesthesia ; pharyngeal spasm ; pharyngeal paral- ysis; laryngeal spasm (Kopp's asthma); "vvhooping cough; aneurismal cough ; pulmonary asthma ; pulmonary vaso-mo- tor paralysis ; angina pectoris ; cardiac neuralgia ; gastrody- nia ; boulimia ; polydipsia ; dyspeptic vomiting ; polyphagia. The spinal accessory nerve .... 259-272 Its superficial and deep points of origin. Its course and distribution. Its filaments of communication. Its relations to the production of voice. The effects of section of the nerve — On phonation ; on respiration ; on deglutition ; on the action of the heart ; on singing. TABLE OF CONTENTS. XV Clinical points pertaining to the nerve. Tonic spasm of sterno-mastoid muscle ; tonic spasm of trape- zius; clonic spasm of sterno-mastoid and trapezius mus- cles ; salaam convulsion of Nevvnham ; unilateral paralysis of sterno-mastoid and trapezius muscles ; bilateral paralysis of sterno-mastoid and trapezius muscles. The hypo-glossal nerve (sub-lingual nerve) . Its superficial and deep points of origin. Its course and distribution. The descendens noni branch. Functions of the nerve : on deglutition ; on articulation. Clinical points pertaining to the nerve. Duchenne's disease : abnormalities of speech ; abnormalities of voice ; impairment of deglutition ; facial deformity ; lingual tremor. Lingual spasm : lingual paralysis. 272-286 PART in. THE SPmAL CORD ...... Its anatomical construction, functions, and clinical bear- ings. Its cervical and lumbar enlargements. Its fissures and columns. Its nerves (their roots and general construction). Its membranes and the cerebro-spinal fluid. Their functions and situation. Appearance of a transverse section of the cord. Its gray matter ; its white matter ; its central canal ; its commissures. Pathological subdivisions of the cord: col- umns of Goll ; columns of Burdach ; columns of Tiirck ; fundamental columns ; direct pyramidal columns ; anterior root zones; posterior root zones; crossed pyramidal col- umns ; direct cerebellar columns. Functions of the spinal cord. (i) Organ of conduction. Paths of motor impulses; paths of sensory impulses; commissural fibers. Fibers of the spinal cord : motor fibers and their function; sensory fibers and their function; commissural fibers and their function. (2) Spinal cord as a nerve center. Reflex action of the cord ; automatic action of the cord ; vaso-motor centers ; cilio-spinal center ; genito-uri- nary center; tonic action on muscles; center of defe- cation ; center of parturition ; center of micturition ; center of erection. (3) Organ of coordination of muscular movements. 287-352 xvi TABLE OF CONTENTS, Clinical points pertaining to the spinal cord. The kinesodic system ; the sesthesodic system ; diseases of its substance. Systematic lesions of ^stiiesodic system. (i) Sclerosis of columns of Goll. {2) Sclerosis of columns of Burdacli (locomotor ataxia). Systematic lesions of kinesodic system. (i) Sclerosis of columns of TurcTc. (2) Sclerosis of lateral columns (spasmodic tabes, tetanoid pa- ralysis, spastic spinal paralysis). {3) Amyotrophic lateral sclerosis of the cord. (4) Myelitis of the anterior horns of the gray matter (atrophic spinal paralysis). (5) Polio-myelitis. Acute variety; infantile spinal paralysis; non-febrile variety ; chronic variety. {&) Progressive muscular atrophy. (7) Central myelitis. Non-systematic or " focal " lesions of the cord. Distinctions between systematic and focal lesions ; their physi- ological effects at different heights, (i) Focal lesions of the upper cervical region. Symptoms referable to the phrenic nerve ; to the respira- tory center ; to the acceleratory center of the heart ; to the pneumogastric nerve. {2) Focal lesions of the cervical enlargement. Symptoms referable to cilio-spinal center; to the ulnar nerve ; to the acceleratory center of the heart ; to the vaso-motor centers. {3) Focal lesions of the mid-dorsal region. Symptoms referable to the lower limbs ; to the genito- urinary organs; to the reflex excitability of the spinal cord; to the lateral columns of the spinal cord; to the rectum. (4) Focal lesions above the lumbar enlargement. Symptoms referable to reflex excitability of the spi- nal cord ; to the genito-urinary organs ; to the rec- tum. (5) Focal lesions of the lumbar enlargement of the spinal cord. Symptoms referable to the sciatic nerve ; to the rec- tum. (6) Focal lesions of one lateral half of the spinal cord. (a) Spinal-hemiplegia — symptoms referable to the inter- costal nerves ; to the upper extremity ; to the lower extremity; to the cilio-spinal center; to the vaso- motor centers. (b) Hemi-paraplegia — symptoms referable to the trunk ; to " trophic " centers ; to increased excitability of the spinal cord ; to the lower limbs. TABLE OF CONTENTS. PART lY. THE SPINAL NERVES . . . . . Their subdivisions and points of escape. The construction and relative size of their roots. The length and inclination of their roots. General axioms of nerve distribution. The upper cervical nerves .... Table of their branches of distribution ; the cervical plexus — its situation, formation, superficial branches, deep branches, and communications with other nerves. The communicans noni nerve: its origin and distribution. The phrenic nerve: its origin, course, surgical relations, and physiological function. Clinical points pertaining to the upper cervical nerves: cervico-occipital neuralgia; diaphragmatic neural- gia ; clonic diaphragmatic spasm (hiccough) ; tonic dia- phragmatic spasm (diaphragmatic tetanus); and diaphrag- matic paralysis. The lower cervical nerves .... Table of their branches of distribution. The brachial plexus : its situation; its formation and abnormalities; its supra- clavicular branches ; its infra-clavicular branches ; its surgi- cal relations ; its communications with other nerves. Nerves of the upper extremity : table of the branches of the outer cord of the brachial plexus; table of the branches of the in- ner cord of the brachial plexus ; table of the branches of the posterior cord of the brachial plexus. The anterior thoracic nerves: their distribution ; their clinical aspects. The exter- nal or musculo-cutaneoiis nerve: its course and distribution to muscles ; its cutaneous distribution ; its relation to the " bent arm " after venesection. Clinical points afforded by it: paralysis and its symptoms; anaesthesia of forearm. The median nerve : its origin, course, and distribution ; its surgical relations; its cutaneous distribution. Clinical points afforded by it : median paralysis and its symptoms ; anfBsthesia and its variations. The internal and lesser in- ternal cutaneous nerves: their origin, course, and distribu- tion; relations to the intercosto-humeral nerve. The ulnar nerve : its origin, course, and distribution ; its surgical rela- tions ; its cutaneous distribution. Chnical points afforded by it: ulnar paralysis, its causes and symptoms; its relation to the surgery of the elbow joint. The siib-scapular nerves: their origin, course, and distribution ; their surgical relations ; their cutaneous distribution. Clinical points afforded by them : scapular paralysis. The circumjlex nerve : its origin, course, and distribution ; its surgical relations ; its cutaneous and articular branches. Clinical points afforded by it: cir- cumflex paralysis; deltoid atrophy. The musculo-spiral 2 XVll PAGES 353-486 362-377 377-419 xvm TABLE OF CONTENTS. nerve: its origin, course, and distribution. Its terminal branches (the radial and interosseous nerves) : their distri- bution to muscles; their cutaneous distribution. Clinical points afforded by it: surgical importance of its peculiar course ; its relation to traumatic paralysis ; rheumatic affec- tions of the nerve. Lead paralysis : theories as to its etiol- ogy; its symptoms; its differential diagnosis ; its duration. The dorsal nerves ...... The thoracic intercostal nerves; the thoracico ahdojninal in- tercostal nertes: their origin, course, and distribution; their relation to the pleura. Clinical points afforded by them: significance and diagnostic value of thoracic pain; signifi- cance of pain in the pit of the stomach; significance of pec- toral pain ; significance and course of pain due to the liver and other viscera. Intercostal neuralgia: its causes; its symptoms ; its differential diagnosis. Neuralgia of the mam- mary gland (mastodynia) : its causes and symptoms; its " puncta dolorosa." Paralysis of the dorsal nerves: its re- lations to kyphosis ; its relations to scoliosis. Paralysis of the extensor muscles of the lumbar region: its diagnostic attitude; its differential diagnosis. The lumbar nerves ...... The lumbar plexus: its situation and formation; its chief branches and their general distribution. The ilio-hypo- gastric nerve: its origin, course, and distribution; neuralgia of the nerve. The ilio-inguinal nerve: its origin, course, and distribution ; neuralgia of the nerve ; its relation to tiie peritonaeum. The external cutaneous nerve : its origin, course, and distribution ; its relation to pains referred to the thigh. The genito-crural nerve : its origin, course, and distribution. Clinical points afforded by it. The anterior crural nerve : its origin, course, and distribution; its physiological func- tion; its distribution to joints; its cutaneous branches. Clinical points afforded by it: its surgical relations ; its rela- tion to pain in the region of the knee. Spasm of the quad- riceps extensor muscle. Crural paralysis: its causes and symptoms. Atrophy of muscles supplied by this nerve. Crural neuralgia: its causes; its "puncta dolorosa"; the lie contracture of Stromeyer." The olturator nerve: its origin, course, and distribution; its distribution to joints; its relation to pain in the vicinity of the knee; ita physiological functions. Clinical points afforded by it: obturator neuralgia; obturator paralysis. The accessory obturator nerve : its origin, course, and distribution ; its ab- normalities. The SACRAL NERVES . Their anatomical peculiarities, and formation; its situation 419-436 457-480 The sacral plexus: its shape its branches of distribution. TABLE OF CONTENTS, XIX The superior gluteal nerve : its origin, course, and distribu- tion ; its physiological function. Clinical points afforded by it: peculiarities of its cutaneous distribution; its surgical relations; gluteal spasm; gluteal paralysis. The muscular Iranches of the sacral plexus: their distribution; their physiological functions. The small sciatic nerve: its origin, course, and distribution; its physiological functions; rela- tion of its perineal branch to the genital organs. The pudic nerve: its origin, course, and distribution; the inferior hemorrhoidal nerve; the perineal nerve; the dorsal nerve of the penis. Clinical points afforded by the pudic nerve : its relations to coitus ; its relations to micturition ; its rela- tions to defecation; neuralgic affection of its branches. The great sciatic nerve: its origin, course, and distribution; its distribution to joints. The external popliteal nerve : its course and branches of distribution. Distribution of nerves to the fascia of the leg. The internal popliteal nerve : its course and branches of distribution. Clinical points afforded by the great sciatic nerve and its branches. Sciatic neuralgia (malum Cotunnii) : its causes ; modifications of its seat ; its characteristic symptoms ; its " puncta dolorosa " ; its motor manifestations ; its vaso-motor effects. Spasms of the lower limb : spasmodic contracture of the hip ; tonic and clonic spasms of extensor and adductor groups of muscles; spasm of the anterior muscles of the leg. Paralysis of the great sciatic nerve or its branches: sciatic paralysis; peroneal paralysis; tibial paralysis; their sensory manifestations; their trophic disturbances. INDEX 487-500 LIST OF ILLUSTEATIONS. no. 1. 9 4. 5. C. r. 8. 9. 10. 11. 12. 13. U. 15. 16. ir. 18. 19. 20. 21. Nerve fibers from the human subject . KolliTcer Cervical and thoracic portions of the SYMPATHETIC . . ... Sappey Lumbar and sacral portions of the sym- pathetic ....." Fibers of Remak (Magnified) . . Robin . Mode of termination of the motor nerves Itouget A diagram of the brain in profile . Quain Vertical section op the encephalon . Hirschfeld A diagram of the brain in transverse VERTICAL SECTION . . . Balton Inferior aspect of the encephalon . Hirsclifeld Convolutions of the internal aspect of the hemispheres .... Sappey A DIAGRAM OF THE FIBERS IN THE CEREBRUM Le BoTh A DIAGRAM OF THE CEREBRAL CONVOLUTIONS DaltOTl Structure of the cerebral convolutions Baillarger A DIAGRAM OF THE SENSORY AND MOTOR TRACTS OF THE BRAIN . . . Seguiu Side view of the special areas op the CEREBRAL CONVOLUTIONS . . . FetrieT Upper view of the special areas of cere- bral . convolutions . . . " a diagram showing the course of nerve impulses in THE BRAIN . . . Dodds . The CORPORA striata . . . Sappey A DIAGRAM TO ILLUSTRATE " CROSSED PARALY- SIS " . . . . . Hammond The CEREBELLUM AND MEDULLA OBLONGATA HlTSChfeld Anterior view of the medulla oblongata Sappey Outline of the skull and its surgical guides . . . . . Topinard and A DIAGRAM OF THE LOBES AND FISSURES OF THE CEREBRUM .... Fevriev Seguin PAGB 6 6 8 9 10 20 21 22 23 25 27 31 33 35 39 41 53 55 60 61 65 70 76 xxu LIST OF ILLUSTRATIONS. FIG. 24. a diagram of the cerebbum in longi- tudinal median section . 25. Lateral view of the special areas of the cerebral cortex 26. Superior view of the special areas of the cerebral cortex 27. Roots of the cranial nerves 28. Olfactory ganglion and nerves . 29. Terminal filaments of the olfactory NERVE ..... 30. Internal branches of the olfactory NERVE ..... 31. Optic tracts, commissure, and nerves 32. A diagram of the decussation of the optic fibers .... 33. A diagram of the optic fibers in the RETINA ..... 34. Relation of the optic nerve and oph- thalmic ARTERY .... 35. Relation of the optic nerve to the blood-vessels, in the orbit 36. A diagram of the defective diameters of the EYE ..... 37. Anterior view of the crystalline lens 38. two cuts of the retina and its elements 39. a diagram to show the limits of color VISION ..... 40. Lachrymal and Meibomian glands 41. Lachrymal apparatus 42. A diagram to show the effects of press- ure on the optic nerve 43. Distribution of the third cranial nerve 44. The ciliary muscle, lens, iris, and cor- nea 4 . . . . 45. The ciliary nerves and choroid coat of eye ..... 46. The nerves of the iris 47. The ciliary nerves 48. A diagram showing the mechanism of the accommodation of vision 49. Muscles of the eyeball 50. A diagram showing the axes of rotation OF THE EYEBALL .... 51. Two DIAGRAMS OF THE ELEMENTS OF THE RETINA ..... 52. Distribution of the fourth cranial NERVE ..... 53. The ophthalmic division of the fifth cranial nerve .... Dalton Terrier Hirachfeld (I KolUTcer Sappey Eirachfeld Flint . Weher . Ranney Bahuchin Mailer and Sappey HirscJiberg Sappey Ranney Hirschfeld Sappey Ficlc. 134 Sappey 136 FkJc . 139 Mailer and Sappey 144 Eirschfeld . 150 (( 15'2 LIST OF ILLUSTBATIONS. no. 54. a diagram of the distribution of the fifth cranial nerve 55. The inferior maxillary division of the FIFTH cranial NERVE 56. The superior maxillary division of the fifth cranial nerve 57. Superficial branches of the fifth and FACIAL nerves .... 58. Cutaneous nerve distribution of the head 59. Distribution of the sixth cranial nerve 60. The superficial branches of the facial nerve ..... 61. a diagram of the branches of the fa- cial nerve .... 62. Expression of the face in "bell's paral- ysis" . . . . . 63. a diagram of the communications between the facial and TRIGEMINUS NERVES 64. The chorda tympani nerve 65. A diagram of the course of the vidian and petrosal NERVES 66. a diagram of the auditory nerve and its branches .... 67. Distribution of the cochlear nerve . 68. General view of the organ of hearing 69. A diagram to illustrate the mechanism of hearing .... 70. The ossicles of the tympanum 71. The bony labyrinth of a new-born child 72. A diagram of the labyrinth, vestibule, AND SEMICIRCULAR CANALS 73. A DIAGRAM OF THE COCHLEA ON TRANS- VERSE SECTION .... 74. A VERTICAL SECTION OF THE " ORGAN OF CORTI " . 75. The two pillars of the " organ of Cor- Tl" 76. Distribution of the cochlear nerves 77. Membrana tympani, seen from within 78. Section of the cochlea of the cat and human fcetus .... 79. The glosso-piiaryngeal nerve 80. A DIAGRAM OF THE GLOSSO-PHARYNGEAL NERVE ..... 81. The papilla of the tongue 82. a circumvallate papilla . 83. The fungiform and filiform papilla 84. The taste-buds .... 85. The cavities of the mouth and pharynx Flower (Modified Hirschfeld Flower Hirschfeld Ranney Corfe . Ranney Hirschfeld Ranney u Sappey Ranney Arnold Rudringer Ranney Waldeyer Sappey Rudringer Sappey Ranney Engelmann Sappey xxin PAGE from) 154 155 156 157 159 176 178 179 181 183 185 186 198 199 200 202 203 204 205 206 207 208 209 212. 214 222 223 224 224 226 228 XXIV LIST OF ILLUSTRATIONS. FIQ. 86. The muscles of the pharynx 87. Anastomoses of the pneumogastric nerve 88. a diagram of the cervical portion of the PNEUMOGASTRIC NERVE 89. a diagram of the thoracic and abdominal portions of the pneumogastric nerve 90. Distribution of the pneumogastric nerve 91. Nerves of the larynx, posterior view 92. Nerves of the larynx, lateral view 93. Branches of the pneumogastric nerve to the heart .... 94. The spinal accessory nerve 95. Posterior view of the muscles of the larynx ..... 96. Lateral view of the muscles of the larynx ..... 97. A DIAGRAM of THE SPINAL ACCESSORY NERVE 98. The glottis, as seen with the laryngo- scope DURING THE EMISSION OF HIGH- pitched sounds .... 99. The spinal accessory nerve 100. Distribution of the hypo-glossal nerve 101. Anastomotic loop formed by the de- scending branch of the hypo-glossal nerve and the internal descending BRANCH of the CERVICAL PLEXUS 102. a diagram of the hypo-glossal nerve and its branches 103. Glosso-labio-laeyngeal paralysis 104. " " " " . . 105. A DIAGRAM OF THE MOTOR POINTS OF THE FACE, SHOWING THE POSITION OF THE ELECTRODES DURING ELECTRIZATION OF SPECIAL MUSCLES AND NERVES . 106. The cervical portion of the spinal CORD ..... 107. The dorsal portion of the spinal cord 108. Inferior portion of the spinal cord and cauda equina .... 109. Transverse section of the spinal cord AT the origin of THE FIFTH PAIR OF cervical nerves 110. Transverse section of the spinal cord of a child six months old, at the middle of the lumbar enlargement . 111. a section of the spinal cord below the medulla oblongata 112. a section of the cervical enlargement OF THE SPINAL COED Sappey Hirachfeld Ranney Eirgchfeld Sappey Bernard Hlrschfeld Sappey u Ranney Le Bon Sajypey Hirschfeld Ranney Hammond Rosenthal (Mod. from) Hirsclifeld Stilling Gerlach Sappey PAGE 230 237 23S 241 242 244 244 245 260 261 261 262 268 265 283 274 275 278 279 282 288 288 288 289 291 295 295 LIST OF ILLUSTRATIONS. XXV FIG. 113. a section of the dorsal eegion of the spinal cord .... 114. a section of the lumbar enlargement of the spinal cord 115. Colored plate showing the subdivisions OF THE spinal CORD 116. A TRANSVERSE SECTION OF THE SPINAL CORD (Diagrammatic) 117. Nerve cell from the anterior horn of the spinal cord of a calf 118. Multipolar nerve cell from the ante- rior HORN of the spinal CORD OF THE OX ..... 119. Transverse section of the gray sub- stance OF the spinal cord 120. Course of motor and sensory paths in the spinal cord 121. Nerve cells from the floor of the ehomboidal sinus in man 122. a diagram to show the decussation of motor nerve fibers IN THE MEDULLA oblongata .... 123. Atrophic spinal paralysis with con- tracture ..... 124. Progressive muscular atrophy of the upper extremity 125. Progressive muscular atrophy. Age of patient, forty-five years 126. a diagram showing the relation of the spinous processes of the vertebra to the spinal nerves and spinal cord 127. a diagram to show the course of the motor and sensory paths in the spi- NAL CORD. .... 128. a diagram to show the relation of the spinous processes of the verte- bra to spinal nerves . 129. The cervical portion of the spinal cord 130. The dorsal portion of the spinal cord 131. The inferior portion of the spinal cord and cauda equina 132. Posterior branch of the second cervi- cal NERVE .... 133. Superficial branches of the cervical PLEXUS ..... 134. The nerve supply of the posterior part OF the head .... 135. The nerve supply of the posterior por- tion OF the head and neck . Sappey 296 a 296 Hammond 297 Seguin . 298 Schultze 308 Belters 305 Gandry 306 Brown-Sequard 307 KolUTcer 308 Fleclisig and Seguin . 327 Hammond 333 u 335 Friedreich 336 Malgaigne and Seguin 340 Brown-Sequard 349 Malgaigne and Hirschfeld . Seguin 350 356 356 u 356 Arnold 363 Hirschfeld 365 Hilton 366 Flower 367 XXVI LIST OF ILLUSTRATIONS. FIO. 136. a diagram of the bbaohial plexus and its bkanohes .... 137. Anteeiob bbanches of the four last cervical and first doesal nebves 138. collatebal bbanches of the bbachial PLEXUS ..... 139. Bbaohial pobtion of the musculo-cuta- neous, median, and ulnab nebves 140. Cutaneous nebves of the antebiob sub- face OF THE FOBEABM AND HAND 141. Cutaneous nebves of the shouldeb and postebiob 8ubface of the abm • . 142. Cutaneous nebves of the postebioe sub- face OF THE FOBEABM AND HAND 143. BbACHIAL POBTION OF THE MUSCULO-CUTA- neous, median, and ulnab nebves 144. Teeminal pobtion of the median and ulnab nebves .... 145. diagbam of the begions of the cutane- ous nebve di8tbibuti0n on the ante- eiob subface of the uppee extbemity and teunk .... 146. The cutaneous nebves of the shouldeb and antebiob subface of the abm 147. The cutaneous nebves of the antebiob subface of the fobeabm and hand . 148. BbACHIAL POBTION OF THE MU8CUL0-CUTA- NEOUS, MEDIAN, AND ULNAB NEBVES 149. TeBMINAL POBTION OF THE MEDIAN AND ulnab nebves ..... 150. The oiboumflex and subscapulab nebves 151. The musculo-spiral nebve . , . 152. The TEBMINAL bbanches of the musoulo- spibal nerve 153. a diagbam of the regions of cutane- ous nebve distbibution on the poste- biob subface of the upper extbemity and tbunk .... 154. The motob points on the outeb aspect of the abm .... 155. The motob points on the inneb side of THE ABM . . . . . 156. The motob points on the extensob (pos- tebioe) ASPECT of the FOBEABM 157. The motob points on the flexob (ante- biob) ASPECT OF THE FOBEABM . 158. The intebcostal nerves . 159. The nerves situated on the postebior part of the trunk Gray . Uirschfeld u Sappey Hirachfeld Sappey 379 380 381 386 389 391 392 394 394 396 899 399 401 401 407 409 409 Flotcer (Modified from) 41 1 Rosenthal " " 415 416 418 . 421 . 423 Flower Hirachfeld u Sappey U (( u (( u LIST OF ILLUSTRATIONS. XXVll FIG. 160. A DIAGRAM OF THE REGIONS OF CIJTANE0U8 NERVE DISTRIBUTION IN THE ANTERIOR SURFACE OF THE UPPER EXTREMITY AND TRUNK ..... 161. A DIAGRAM OF THE REGIONS OF CUTANEOUS NERVE DISTRIBUTION ON THE POSTERIOR SURFACE OF THE UPPER EXTREMITY AND TRUNK ..... 162. The lumbar plexus 163. The cutaneous nerves of the thigh 164. The muscular branches of the anterior and internal portions of the thigh 165. a diagram of the cutaneous supply of the anterior aspect of the lower extremity .... 166. Cutaneous nerves of the anterior part OF THE thigh . . . 167. Diagram of the cutaneous supply of the posterior aspect of the lower extremities .... 168. Muscular BRANCHES of the anterior and internal portions OF THE THIGH 169. The small sciatic nerve with its branches of distribution and termination 170. The great sciatic nebve with its branches of distribution and ter*- mination ..... 171. The external popliteal nerve . 172. The internal popliteal nerve . 173. The external saphenous nerve and its ACCESSORY, the COMMUNICANS PERONEI 174. The plantar nerves, their course, anas- tomoses, and distribution 175. The deep branch of the external plan- tar nerve .... 176. The motor points on the posterior as- pect OF the thigh 177. The motor points on the anterior as- pect OF THE thigh 178. The motor points on the inner aspect of the leg .... 179. The motor points on the outer aspect OF the leg .... Flower (Modified from) 425 Hirsclifeld 429 435 442 445 Flower (Modified from) 446 Sappey , . 449 Flower (Modified from) 451 Sappey . .453 " . . . 465 " . . 470 . 471 . 473 " . . 475 " . . 476 . 477 Eosentlial (Mod. from) 480 482 484 486 u u (; u (I u GENERAL lE^TRODUCTIOJN'. \THE NERVOUS SYSTEM CONSIDERED AS A WHOLE, AND THE AXIOMS OF NERVE DISTRIBUTION. GEITEEAL INTEODUOTION. ■■T GrEiSTTLEMEN : The subject of the nerves, which has been chosen as the th^me of my winter's course of lectures, is one which probably comprises more points of practical interest than any other portion of anatomy. I say of practical inter- est, because there is hardly a field of medicine or of surgery where the nervous system does not help to explain many of the symptoms which might otherwise tend to possibly mis- lead the practitioner, and where it does not also afford invalu- able aid in the diagnosis of obscure gLffections which might remain unrecognized, without a knowledge of the nerves and of their distribution and function, till the opportunity of 1 relief to the patient has passed. IB The distribution of those small nerve filaments which sup- T ply the skin of the body with sensation, and thus allow of the ' perception of external impressions, such as those of heat, cold, pain, and touch, possesses to-day an importance which is not confined to the researches of the physiologist, but which the advanced physician and surgeon are both keenly alive to grasp in all its practical detail. In every work now published upon diseases of the nervous system, you will find plates, which, in less modem treatises, have no analogue ; which plates are designed to show the situation of certain motor points on the cutaneous surface of the different anatomical regions of the body, where the elec- tric current can be best applied to accomplish certain desired effects. 4 GENERAL INTRODUCTION^, The important relationship which exists between the nerves of the skin, the muscles underneath it, and the joints which those muscles move, is affording the enlightened physician a means of tracing the seat of obscure affections, by the use of certain general rules governing the nerve supply of the body, with a degree of accuracy and ease which strikes those, not familiar with the method, as remarkable. \j ( The investigations of Charcot,' Ferrier,' Brown- Sequard,' Broca,* Bouillaud," Andral,' and a host of others, have awakened the profession to the fact that many of the old ideas of the physiology of the brain and the spinal cord are radically wrong ; and that, by symptoms referable to certain anatomical regions, the existence of disease tn certain corre- sponding parts of the brain or spinal cord may be positively localized. To what extent this new guide to diagnosis, given us by means of experiments calculated to determine the pre- cise distribution of the nervons system, may be developed in the future, time alone will show ; but we have already ample proof that some positive information of a practical charactej? has been gained, and much advance has been made in the accurate knowledge of the anatomy of the nervous centers. When we consider that every act which distinguishes the animated being from the corpse is dependent upon the influ- ence of the nerves, and that, without these electric wires, the heart would cease to throb, the lungs no longer perform their function, the eye no longer be capable of vision, the ear no longer perceive sound, and that smell, taste, expression, and movement would cease to exist, we can then understand how much of physiological interest must center around this special study, and how necessary is the thorough understanding of the distribution and function of the individual nerves, if we ' " Localizations dans Ics maladies c^rebrales." 2 "■ Functions of the Brain " ; " Localization of Cerebral Disease." 2 " Lectures on the Physiological Pathology of the Brain." 4 " Bull, de la Soc. Anat.," 1861. ' " Recherches experimentales sur les fonctions du ccrvcau." " Jour, de Physiolo- gie," Paris, 1830. "Trait6 de l'Enc6phalite," Paris, 1825. « " Clinique M6dicalc." GENERAL INTRODUCTION. 5 ever hope to attain a compreliensive grasp of the general plan of our construction. During the last session, I closed my course of lectures with a description of the general construction of nerves and the anatomy of the human brain. It will assist us, in our study of the distribution and practical utility of the separate nerves of the body, to hastily review the main classilications of nerves and the general plan upon which the nervous system is formed. The nervous system of the human race consists of the fol- lowing component parts : 1st, Cerebro-spinal system. ( Brain, The cerebro-spinal ■< Medulla oblongata, axis : f Spinal cord. The motor nerves. The sensory nerves. 2d. The sympathetic nerve, 8d. Various ganglia, connected with special nerves. The cerebrospinal axis includes those nerve centers in- closed within the cavities of the cranium, and of the spinal Fig. 1. — Nerve fibers from the human subject ; magnified 350 diameters. (KOlliker.) Four small fibers, of which two are varicose, one medium-sized fiber with borders of sin- gle contour, and four large fibers ; of the latter, two have a double contour and two contain granular matter. 3 GENERAL INTRODUCTION. Fig. 2.— Cervical ijiiii>ailutic. (Sappcy.) 1, 1, 1, right pneumogastric ; 2, glosso-pharyngcal ; 3, spinal accessory; 4, divided trunk of the sublingual ; 6, 6, 5, chain of ganglia of the sympathetic ; 6, superior cervical ganglion; 7, branches from this ganglion to the carotid ; 8. nerve of Jacobson; 9, iieo filaments from the facial, one to the spheno-palatin^ and tJie other to the otic gan- glion ; 10, motor oculi extcrnus ; 11, ophthalmic ganglion, receiving a motor filament from the motor oculi communis and a sensory f lament from the nasal branch of the ffth ; 12, spheno-palatinc ganglion ; 13, otic ganglion ; 14, lingual branch of the fifth GENERAL INTRODUCTION. 7 nerve; 15, submaxillary gangVion ; 16, 17, superior laryngeal nerve; 18, external laryngeal nerve; 19, 20, recurrent laryngeal nerve; 21, 22, 23, anterior hranclics of • the upper four ccri ical nerves^ sending filaments to the superior cervical sympathetic ganglion; 24, anterior branches of the fifth and sixth cervical nerve sending filaments to the middle cervical ganglion ; 25, 26, anterior branches of the seventh and eighth cervical and the first doj'sal nerves, setiding filaments to the inferior cervical ganglion ; 27, middle cervical ganglion ; 28, cord connecting the two ganglia ; 29, inferior cervi- cal ganglion ; 30, HI, filaments connecting this with the middle ganglion ; 32, superior cardiac nerve ; 33, middle cardiac nerve ; 34, inferior cardiac nerve ; 35, 35, cardiac plexus ; 36, ganglion of the cardiac plexus ; 37, nerve following the right coronary artery ; 38, 38, intercostal nerves with their two filaments of communication with the thoracic ganglia ; 39, 40, 41, great splanchnic nerve ; 42, lesser sptlanchnic nerve ; 43, 43, solar plexus ; 44, left pneumogastric ; 45, right pneumogastric ; 46, lower end of the phrenic nerve ; 47, section of the right bi'onchus ; 48, arch of the aorta ; 49, right auricle ; 50, right ventricle; 51, 52, pulmonary artery ; 53, right half of the stomach ; 54, section of the diaphragm. column, viz., the brain, medulla oblongata, and spinal cord. The second component part of the cerebro-spinal system, viz., the motor nerves, are efferent nerves, which carry the impulses of the nerve centers to the muscles. The third component part, the sensory nerves, are afferent nerves^ which carry only sensory impressions from the periphery of the body to the nerve centers, viz., to the brain or spinal cord. The sympathetic nerxe' comprises a continuous chain of nerve fibers and ganglionic enlargements, which extends from the head to the coccyx, on both sides of the spinal column, and which is in constant communication, along its course, with branches of the cerebro-spinal system of nerves. It sup- plies branches to various ganglia of the thorax and abdomen, i and helps to form the plexuses of nerves which ramify upon I the coats of all the principal blood-vessels, and which accom- ! pany them throughout the length of their course. It is by ' means of these plexuses upon the blood-vessels that the sym- pathetic nerve is enabled to control the involuntary muscular I fibers within the coats of the blood-vessels, and thus to regii- i late the vascular supply of the various tissues and organs of the body ; and the nerve fibers of the sympathetic are there- fore often called the ''nerves of organic life," since they regu- late the life of tissues by controlling their blood supply, while the cerebro-spinal nerves are contradistinguished as the "nerves of animal life," since they control those acts which are essential to the life of the individual, such as muscular 1 See Fig. 2 and Fig. 3. GENERAL INTRODUCTION. Fig. 3. — Lumbar and sacral portions of the sympathetic. (Sappey.) 1, section of the diaphragm ; 2, lower end of the oesophagus ; o, left half of the stomach ; 4, small intestine ; 6, sigmoid flexure of the colon ; 6, rectum ; 7, bladder ; 8, pros- tate ; 9, lower end of the left pneumogastvic ; 10, lower end of the right pncumogas- trie; 11, solar plexus; 12, lover end of the great splanchnic nn-ve ; 13, lower aid nf the lesser splanchnic nerve ; 14, 14, last tico thoracic ganglia ; 15, .15, the four lumbar ganglia; 16, 16, 17, 17, branches from the lumbar ganglia; 18, superior mesenteric plexus; 19, 21, 22, 23, aortic lumhar plexus ; 20, infenor mesenteric plexus; 24, 24, saa^al portion of the si/mpaihetic ; 25, 25, 26, 26, 27, 27, hypogastric plexus ; 28, 29, 30, tenth, eleventh, and twelfth dorsal nerves ; 31, 32, 33, 34, 35, 36, 37, 38, 39, lum- bar and sacral nerves. GENERAL INTRODUCTION. 9 movement, respiration, etc. The frequent communication be- tween tlie sympathetic nerves and those of the cerebro-spinal system renders the actions of the two systems in perfect ac- cord, and thus supports the universal law of Jiarmony which is so beautifully illustrated in all the works of ]S"ature. The cerebro-spinal nerves comprise those which escape from the foramina of the cranium, called the cranial nerves^ and those which are given off from the spinal cord, which escape from the spinal canal by means of foramina between the laminse of the vertebrae, called the ''inter- vertebral fora- mina." These latter nerves are called spinal nerves^ in con- tradistinction to the cranial nerves. All of the spinal nerves arise by tico roots^ thus indicating that they are provided with both motor and sensory fila- ments, the former of which constitute the an- terior and the latter the posterior root ; while the cranial nerves are, in some instances, similarly constructed, as to having two dis- tinct roots, while others have only one. The reason of this anatomical variation is ex- plained by the fact that some of the cranial nerves are destitute of motor fibers, some of sensory fibers, while others are endowed with a special function, such as sight, smell, hear- ing, and taste. In the course of lectures which I propose to deliver before you this winter, it is my in- tention not only to give the anatomical ori- gin, course, and distribution of the various nerves, but also such points of practical value as may be suggested in connection with each, which will aid in remembering the peculi- arities which each presents, and possibly to guide you in your practice at the bedside of the sick. The study of the practical bearing of the distribution of the nerves is to-day assuming Fig. 4. — Fibers of Remak ; magni- fied 300 diame- ters. (Robin.) With the gelatinous fibers are seen two of the ordina- ry, dark-bordered nerve fibers. 10 GENERAL INTRODUCTION. an importance in diagnosis wliicli can not be over-estimated ; while the physiological phenomena produced by them have a direct influence upon the proper performance of all those functions of the body which may be considered as vital to it. It is claimed by John Hilton ' that, if we trace the dis- tribution of the motor nerve fllaments from any special nerve trunk to the muscles, we shall find that only those muscles are supplied by each of the individual nerves which are re- quired to render the performance of the functions^ for which that nerve was designed, complete ; and that, if muscles were classified on a basis of their nerve supply, instead of in groups of mere relationship as to locality, a self-evident phy- siological relation would be shown which would tend greatly Fia. 5. — Mode of termination of the motor nerves. (Rouget.) A, primitive fasciculus of the thyro-hyoid muscle of the human subject, and its nerve tube: 1, 1, primitive muscular fasciculus; 2, nerve tube; 3, medullary substance of the tube, which is seen extending to tlie terminal plate, where it disappears ; 4, ter- minal plate situated beneath the sarcolemma, that is to say, between it and the ele- mentary fibrillae ; 5, 5, sarcolemma. B. primitive fasciculus of the intercostal muscle of the lizard, in which a nerve tube ter- minates: 1, 1, sheath of the nerve tube; 2, nucleus of the sheath; 3, 3, sarcolemma becoming continuous with the sheath ; 4, medullary substance of the nerve tube ceas- ing abruptly at the site of the terminal plate ; 5, 5, terminal plate ; 6, 6, nuclei of the plate ; 7, 7, granular substance which forms the principal clement of the terminal plate, and which is continuous with the axis cylinder; 8, 8, undulations of the sarco- lemma reproducing those of the fibrillie ; 9, 9, nuclei of the sarcolemma. to simplify a knowledge of the muscular system in its prac- tical bearings, and to prove a design on the part of the Creator. ^ " Rest and Pain," Loudon. (Now York, 1879.) GENERAL INTRODUCTION. 11 Thus, lie says, we frequently find muscles close together and still supplied by separate nerves, one of which has possi- bly to go a long way out of a direct course to reach it, which is contrary to the usual method of JS'ature, who always em- ploys the simplest means to accomplish her designs ; but, if we examine the action of these two muscles, we shall find that each one acts in unison with the other muscles sup- plied by the same nerve, and that to produce this perfect accord Nature takes what, to a hasty glance, would seem to be a needless step. He also lays down certain axioms, pertaining to the distri- bution of nerves and the diagnostic value of pain, which will be often repeated in these lectures, and can not but be most profitable to those who use them as a guide. They are as follows : "Superficial pains on both sides of the body, which are symmetrical, imply an origin or cause, the seat of which is central or bilateral ; while unilateral pain implies a seat of origin which is one-sided, and, as a rule, exists on the same side of the body as thepain^ The bearings of this first axiom will be rendered far more apparent when the regions of the neck and trunk are con- sidered, since the symptom of local pain is of the greatest value in connection with diseases affecting the bones of the spinal column and the spinal cord which they invest ; but the same rule may be applied to any of the cranial nerves, with a degree of certainty which seldom admits of error. Thus Hilton reports a case where a fracture of the base of the skull, involving the orbit, produced amaurosis and tension of that region, with extreme local pain. A grooved probe, passed along the roof of the orbit, revealed pus, as was sus- pected to exist, which was evacuated by the separation of the blades of an ordinary dressing forceps. As further examples of this axiom, a toothache may thus accompany an inflamed condition of tlie temporo-maxillary articulation, or it may create it. Again, opium introduced into the auditory canal will often instantaneously relieve 12 GENERAL INTRODUCTION, toothache and stiffness of the jaws, by having a narcotic effect upon the peripheral filaments of the same nerves, whose main trunks are distributed to the other regions mentioned as re- lieved. Severe earache may result directly from the nervous irri- tation of a diseased tooth, since the'filaments of the fifth nerve are distributed to both the ear and the teeth, and thus pain may be felt at a point apparently disconnected from the seat of irritation. Earache is frequently the result of malignant ulceration of the tongue, since both regions receive a portion of their nervous supply from the fifth cranial nerve. The second axiom is as follows : '' TJie same trunks of nerves^ whose branches supply the groups of muscles moving a joint furnish also a distribution of nerves to the skin over the insertions of the same muscles ; and the interior of the joint moved by these muscles receives a nerve supply from the same source.^^ By this axiom, a physiological harmony is created between these various cooperating structures. Thus any joint, when inflamed, may, by a reflex act through motor branches de- rived from the same trunk by which it is itself supplied, con- trol the muscles which move it, and thus insure the rest and quiet necessary to its own repair. Spots of local tenderness in the cutaneous surface may, for this reason, likewise be often considered as a guide to a source of irritation of some of the structures supplied by the same nerve, viz., the muscles underneath it, or the joints which are moved by them ; and thus even remote affections can be accurately determined, which, were this axiom not used as a guide, might escape recognition till an advanced stage of the disease had been reached. It is well, however, to quote one other axiom, laid down by the same author, before leaving the subject of the diag- nostic value of the cutaneous nerves as indicators of existing disease of other organs, viz. : " Every fascia of the body has a muscle or muscles at- GENERAL INTRODUCTION. 13 tacJied to it^ and eceYy fascia must he considered as one of the points of insertion of the muscles connected to it, in fol- lowing the previous axiom as to the cutaneous distribution of nerves." This guide is especially important in case the rule should be applied to the extremities (arms and legs) where these fasciae extend over large surfaces, more or less remote from, and ap- parently unconnected with, the muscles attached to them ; but it is mentioned in this connection, for the special object of calling your attention to those general rules which govern the distribution of the nerves in their entirety, before proceed- ing to apply them in all their individual bearings. Without this nervous association between the muscular structures and those composing the joints, there could be no intimation given by the internal parts of their exhaustion or fatigue. Again, through the medium of this same association between the skin and the muscles, great security is given to the joints, by the muscles being made aware of the point of contact of any extraneous force or violence. Their involun- tary contraction instinctively makes the tissues surrounding the joints tense and rigid, and this brings about an improved defense for the sub-adjacent joint structures. From the conclusion of his great work, in which Hilton ' endeavors to prove that mechanical rest may be used as a cure for most of the surgical disorders, the following sen- tences are quoted, since they can not be too often repeated ; ''I have endeavored to impress upon you the fact that every pain has its distinct and pregnant signification if we will hut carefully search for it. ''From the pain which follows the intrusion of a particle of dust on to the conjunctiva, and the closure of the eyelid for the security of rest, up to the most formidable diseases which we have to treat, pain the monitor, and rest the cure, are starting points for contemplation, which should ever be present to the mind of the surgeon." Let us now pass to the special consideration of the brain ^ Op. cit. 14: GENERAL INTRODUCTION: and each of the twelve nerves of the cranium, and note the more important facts presented by each, which may tend to elucidate its function, or to explain many direct and reflex phenomena which are often of great value in the diagnosis of obscure aifections. Later in the course, we will consider the anatomy of the spinal cord and the nerves which arise from it, noting, in each instance, such points as tend to elucidate the function of the part under consideration, and also such clinical facts as can be constantly applied in your daily association with the sick, when difficult questions of diagnosis arise, or when valuable suggestions, as to the methods of treatment employed, seem to be the direct outgrowth of your anatomical study. Some three years since, my friend Professor E. C. Seguin addressed a class, in beginning a course' upon a somewhat similar subject, with words of counsel and earnest pleading for higher professional attainments, which are well worthy of repetition. I therefore quote them to you in the same spirit, trusting that they will kindle in you a renewed vigor and en- thusiasm in this special department of science : " In practice, when we have completed the examination of a patient, several questions are put to us by the patient, by his friends, or by ourselves. These are, in chronological order : Is there disease i Where is the disease ? What is the disease ? What are we to do for the cure of the disease or for the relief of the patient ? Will the patient die or recover ? "Of these questions, the one which our client and the world at large consider the most important is the fourth— that relating to treatment and cure. This preference is natural, but highly unscientific ; it is a manifestation of that untrained mental action which demands results and scorns methods, which welcomes empirical achievements (provided they be agreeable), and which conduces to the perpetuation of quack- ery of all kinds. But, to the physician who is not a mere pre- scription writer, who aims at infusing as much science into * Delivered before the students of the College of Physicians and Surgeons of New York City, 1878. GENERAL INTRODUCTION, 15 his practice as possible, and who believes that he is not in the world for the purpose of gratifying his patients at so much per visit, but that he owes himself a debt of training and self- culture, and who has a sincere regard for science — to such a physician the first three questions assume a Justly great im- portance. Pray observe that I do not say paramount impor- tance, but great importance. And the superiority of the hu- manitarian over the scientific duty becomes less glaring if we bear in mind the truth — and I firmly believe it to be such — that success in treatment now depends, and in the future will still more closely depend, upon the scientific study of the hu- man subject in health and disease. In other words, I would impress you with my own conviction that the best-trained and most scientific physician, if he be not a closet student and the- orizer, is the best practitioner. "We occasionally hear of an over-fine diagnosis, of ex- treme caution in the treatment of disease, and of the sweeping application of physiological laws to practice by men who are said to be ' too scientific ' ; but who can number the errors, nay, the sacrifices of life, which must be laid at the door of the falsely so-called 'practical men,' who despise learning and scientific methods? Those of us who see something of the rarer and more formidable kinds of disease fully realize that in medicine, as probably in other applicable sciences, igno- rance leads to rashness and crudity in practice, while ripe knowledge conduces to success, or, at any rate, to caution in prognosis and expectancy in treatment. "Of the three diagnostic questions — Is there disease? Where is the disease ? What is the disease % — the second is the one which forms the key-note of these lectures. Where is the lesion producing the disordered actions or symptoms ? The method to be followed in arriving at the solution of this question varies somewhat in different departments of medi- cine. Some lesions can be seen by the trained unaided eye, or felt by the skilled hand ; the seat of others can be deter- mined by auscultation and percussion, by the aid of instru- ments, such as the ophthalmoscope, laryngoscope, speculum. 16 GENERAL INTRODUGTIOK etc. But, in the study of the nervous system, greater difficul- ties are met with ; we are, to a great extent, deprived of these physical aids ; we can not appreciate the condition of the brain and spinal cord directly by our special senses, but only by a proper interpretation of the way in which the functions of these parts are performed. In other words, the diagnosis must be made chiefly by reasoning." To the words above quoted, I can add nothing, save an earnest endeavor to so place the subject matter before you as to render it within the grasp of your full comprehension, pro- vided you, in turn, earnestly seek to master it. THE BRAIN. ITS ANATOMY, FUNCTIONS, AND CLINICAL ASPECTS. THE BEAIISr It is with a sense of the difficulty of this task that I en- deavor to select, from an enormous amount of experimental research regarding the anatomy of the encephalon, or brain, such points as seem to be of special interest, or which may be made a basis of reasoning when circumstances arise that demand analytical inquiry into the probable cause of any dis- eased condition which may exist. The anatomy of the brain is so complex that it can be treated of to advantage only by a minute a^d fully illustrated description, such as can be found either in exhaustive anatomical works or in treatises upon the special descriptive anatomy of the nervous system. In addition to this cause of impediment, w^e are, as yet, igno- rant of the exact structure of many of its parts, and also of the arrangement and physiology of other portions. The brain consists of a number of ganglia which are con- nected with each other, and also, by means of the different columns of the spinal cord, with the motor and sensory nerves of the head, the trunk, and the upper and lower extremities. tiie functions of some of these separate ganglia are more or ss completely understood ; but there still exist masses of gray substance scattered throughout the brain, the special physiological bearings of which are as yet obscure or com- pletely unknown. The gray matter of the hemispheres of the cerebrum has been, and still is, a source of perplexity to the experimental physiologist ; and while the fact seems proven that distinct portions of this large expanse of gray matter 20 THE BRAm. have each some special function, it is still impossible, as yet, to say positively what the properties of each locality are. Fig. 6, — A diagram of the brain in profile. (Modified from Quain.) This cerebrum is represented in this diagram as separated from the cerebellum more than it naturally should be, in order to show certain important parts. A, the cere- brum ; B, the cerebellum ; C, the pons Varolii ; D, the medulla oblongata ; E, the c?*M.s i-erebri ; F, the olivary body ; G, the tubercula quadrigemina ; S, the fismire of Sylvius ; R, the fissure of Rolando ; a^ peduncles of cerebrum ; b, superior peduncles of the cerebellum. ; c, middle peduncle of the cerebellum ; d, inferior peduncles of the cerebellum ; b, E, a, form the isthmus cncephali. If we confine ourselves, then, strictly to the limits of posi- tive information, we can recognize only the following parts as distinct ganglia : ' 1. The gray matter of the cerebral hemi- spheres ; 2. The gray matter of the cerebellum ; 3. The olfac- tory ganglia ; 4. The gray matter of the corpora striata ; 5. The gray matter of the optic thalami ; 6. The tubercula quadrigemina ; 7. The gray matter of the pons Varolii, or the tuber annulare ; 8. The ganglion of the medulla oblongata." There are other parts of the encephalon which have been the field of speculation and investigation, but the positive knowledge gained has been of a purely anatomical character,' and little is yet known of their physiological import. As will ' See Figs. 6, 7, and 8 of this volume. ' Darling and Ranney, " Essentials of Anatomy." G. P. Putnam's Sons : New York, 1880. ' See articles by Flechsig, Luschka, Charcot, Lockhart Clarke, Daltou, Spitzka, and many others. GENERAL CONSTRUCTION. 21 be mentioned in the description of the deep fibers of origin "^ of some of the cranial nerves, the anatomical arrangement may often suggest hypotheses which are attractive, and which tend to explain the object which Nature had in view in so Fig. T. — Vertical section of the encephalon. (Hirschfeld.) 1, medulla oblongata ; 2, tuher annulare ; 3, cerebral peduncle ; 4, cerebellum ; 5, aque- duct of Sylvius; 6, valve of Vieussens ; 7, tubercula quadrigemina ; 8, pineal gland ; 9, inferior peduncle ; 10, superior peduncle ; 11, middle portion of the great cerebral fissure; VI, optic thalamus ; 13, 13, gray commissure ; 14, choroid plexus ; 15, infun- dibulum ; \%, pituitary body ; 17, tuber cinereum; 18, bulb of the fornix; 19, ante- rior perforated space ; 20, root of the motor oculi communis; 21, optic nerve; 22, anterior commissure of the cerebrum ; 23, foramen of Monro ; 24, section of the for- nix ; 25, septum lucidum ; 26, 27, 28, corpus callosum ; 29, 30, 31, 32, 33, 34, convo- lutions and sulci of the cerebrum. The olfactoi'y ganglia and corpora striata are not shown in this section. constructing the part ; yet many of these theories depend upon well- observed clinical facts rather than upon experi- mental research. The limited space of time which we can devote to this course of lectures will preclude the insertion of much that is purely anatomical, and thus a full comprehension of many of the points mentioned may be rendered difficult, unless you occasionally consult some of the text-books upon that sub- ject, in case any of the terms used are unfamiliar. Many statements may also appear somewhat dogmatic, since it will ^ See Lectures on " Optic, Third, and Fifth Nerves," in particular. 4 22 THE BRAIN. not be possible to enter into all the methods of investigation from which some of the conclusions have been drawn, or to quote authorities in support of every proposition where there chances to be a conflict of opinion. Weight of the Brain and of its Component Parts. — That the shape of the cranium may be employed to estimate the relative size of the different parts of the encephalon, and that the circumference of the head and the height of the skull above the orifice of the ear may also relatively indicate the measurements of the cerebrum and its basal ganglia (which Fio. 8. — A diagram of brain in transverse vertical section. (After Dalton.) 1 , cms cerebri ; 2, internal capsule ; 3, optic thalamus ; 4, corpus striatum ; C C, corpus callosum ; L N, lenticular nucleus ; S, fissure of Sylvius ; Fo, gyrus fornicatus ; F', first frontal convolution; F", second frontal convolution; F'", third frontal convo- lution ; T', first temporal convolution ; T", second temporal convolution ; T'", third temporal convolution ; H, gyrus hippocampi. are inclosed within it), have already been pointed out in pre- vious lectures which I have delivered before you. The varia- tions in the skulls of the different nations indicate an amount of brain which is in the direct ratio to the facial angle of Camper. ' The average weight of the brain of a healthy adult of the Caucasian race has been given, by most of the promi- ' See article by the author on the " Osteology of the Head," '* Medical Record," Octo- ber 16, 1880. WEIGHT OF COMPONENT PARTS. 23 nent investigators upon this subject, as about fifty ounces in the male, and some six ounces less in the female.' In the new-born infant, the weight of the brain, in the two sexes, is more nearly alike, being in the region of eleven ounces for Fig. 9. — Inferior aspect of the encephalon. (After Hirschfeld.) 1,1, anterior lobe of the cerebrum ; 2, sphenoidal portion of the posterior lobe ; 3, 3, oc- cipital portion of the same lobe ; 4, anterior extremity of the median fissure ; 5, pos- terior extremity of the same ; 6, 6, fissure of Sylvius ; 7, anterior perforated space ; 8, tuber cinereum and pituitary body ; 9, corpora albicantia ; 10, interpeduncular space (posterior perforated space); 11, crura cerebri; 12, pons Varolii; 13, me- dulla oblongata; 14, anterior pyramids; 15, olivary body ; 16, restiforra body (only partially visible); 17, 17, hemispheres of the cerebellum; 18, fissure separating these hemispheres ; 19, 19, first and second convolutions of the inferior aspect of the frontal lobe with the intervening sulcus ; 20, external convolutions of the frontal lobe; 21, optic tract; 22, olfactory nerve ; 22', section of olfactory nerve, showing Its triangular prismatic shape : the trunk has been raised to show the sulcus in which it is lodged ; 23, ganglion of the olfactory nerve ; 24, optic chiasm ; 25, motor oculi ; 26, pathcticus ; 27, trigeminus ; 28, abducens ; 29, facial ; 30, auditory nerve and nerve of Wrisberg ; 31, glosso-pharyngeal ; 32, pneumogastric ; 3, 3, spinal accessory ; 34, hypo-glossal. the male child and ten ounces for the female. The rapidity of growth of the brain is not uniform throughout the differ- ent periods of life, since it grows rapidly until the age of ' See researches of Reid, Tiedmann, Sims, and Quain. 24 THE BRAIN. seven years, then less rapidly until the age of forty is reached, when it attains its full development, and after that age it decreases in weight about one ounce for every period of ten years. The comparative weights of the component parts of the encephalon are, in approximate figures, about one fiftieth of the entire weight for the pons Varolii and the medulla oblon- gata, taken together ; one tenth of the entire weight for the cerebellum ; and the balance of the total weight for the cere- brum and the basal ganglia inclosed within its substance. These proportions also show a slight variation in the two sexes, but not to so marked an extent as to render this statement far from a correct one. It may be stated, as a rule, that the relative proportion of the cerebrum to that of the cerebellum is greater in the intel- lectual races ; and that the cerebrum is developed in individ- uals in proportion to their intellectual power, although the absolute size may not be taken as a guide to the quality of the mind, since it is undoubtedly true that the brain can be im- proved, in quality, by exercise, as well as the muscular tissue. That there are important individual differences in the quality of the generating nervous matter is evidenced by the fact that some small brains actually accomplish more and better work than larger ones, and that many women often show a higher degree of mental acumen than men, in spite of the fact that they have brains which are lighter in avoirdupois. From the most carefully prepared table of the weight of brain substance possessed by men of renown as intellectual giants, as well as those which revealed an unusual develop- ment of brain after death, contained in the work of a promi- nent author,* the following interesting facts are revealed : The heaviest brains " on record (where the statements are to be relied upon) were possessed by a congenital imbecile and an ignorant bricklayer, both of whom outweighed Cuvier and 1 A. Flint, Jr., " Text-Book of Physiology." D. Appleton & Co., New York. ' Con{^enital imbecile, aged thirty, 70^ ounces of brain substance; bricklayer, 67 ounces; Cuvier, 64 J ounces; Abercrombie, 63 ounces ; Webster, 53^ ounces; Agassiz, 53^ ounces. THE CEREBRUM. 25 Abercrombie ; while a boy of thirteen years of age had five ounces more brain than Webster and Agassiz. Such a table shows the utter absurdity of attempting to apply to individu- als the rule that the greatest brain power is possessed by the one possessing the greatest amount of brain substance. Fig. 10. — Convolutio7is on the internal aspect of the hemisphei-es. (After Sappey.) 1, frontal lobe ; 2, sphenoidal lobe ; 3, 3, convolution of the corpus callosum ; 4, 4, convo- lutions forming the middle group of the internal surface ; 5, 5, convolutions of the anterior group ; 6, convolutions of the posterior group ; 7, sulcus separating the mid- dle from the posterior group ; 8, sulcus separating the anterior and the middle group ; 9, section of the corpus callosum; 10, genu of the corpus callosum; 11, rostrum of the corpus callosum; 12, posterior extremity of the corpus callosum; 13, fornix; 14, section of the fornix ; 15, left anterior crus of the fornix, passing into the inter- nal wall of the optic thalamus, to reach the corresponding corpus albicans — course indicated by a dotted line; 16, foramen of Monro; 17, corpus albicans, in which the anterior crus of the fornix bends upon itself, in the form of a figure of eight, to be lost in the substance of the optic thalamus ; 18, septum lucidum ; 19, section of the choroid plexus ; 20, pineal gland ; 21, left superior peduncle of the same; 22, sec- tion of the gray commissure of the third ventricle ; 23, tubercula quadrigemina, above which are seen the pineal gland with its inferior peduncle and the posterior com- missure ; 24, section of the anterior commissure ; 25, aqueduct of Sylvius ; 26, sec- tion of the valve of Vieussens ; 27, fourth ventricle ; 28, 28, section of the middle lobe of the cerebellum; 29, arbor vitas; 30, corpus cinereum; 31, pituitary body; 32, optic nerve ; 33, pons Varolii ; 34, medulla oblongata. I THE CEREBRUM. The cerebrum fills the anterior and the middle fossse of the 26 THE BRAIJSr. above the tentorium cerebelli, since that membrane supports its posterior part. Its gray matter is not alone confined to its exterior surface, where it covers all of the convolutions and the sulci between them, but it is also present as two distinct collections, in the region of the floor of the brain called the corpora striata, ' and the optic thalami. To these latter col- lections of gray matter the term " hasal ganglia " is applied, on account of their relative situation within the substance of the cerebrum. While it will enable you to more clearly understand the functions of those parts, concerning which experiment or clinical observation has gained positive knowledge, by study- ing each of these basal ganglia apart from the cerebrum, still the general relation of the component parts of the hemispheres will have to be first mentioned, in order to proi)erly appreci- ate the bearing of facts which will be discussed later in this chapter. The gray matter which covers the exterior portion of each hemisphere of the cerebrum is connected with white nerve fibers, which may be divided into two classes ; the first of which can be traced from the various parts of the exterior of the cerebrum toward the basal ganglia, while the second com- prise certain curved commissural fibers, which pass into the white substance for a certain dejith, and then return to the gray matter of the surface, thus serving to connect different convolutions with each other. The first set mentioned are called " converging fibers,'''^ since all the different points upon the large expanse of surface of the cerebrum send fibers which pass through either the corpus striatum or the optic thalamus of the same side,' and they thus present a converging appear- ance, on an appropriate section of the brain being made. We ' This ganglion, in each hemisphere, consists of two portions, called the " caudate nu- cleus" and the "lenticular nucleus," which are separated from each other by the so-called " internal capsule " of the cerebrum. These subdivisions are shown in Fig. 8 of this volume. 2 This statement is only approximately correct, since the internal capsule is probably the chief path for these fibers. To what extent the basal ganglia are directly associated with the fibers of the cortex is, as yet, an unsolved problem. FUNCTIONS OF CEREBRUM. 27 know, from clinical facts associated with cases of cerebral hsemorrhage and cerebral softening, that the cerebrum must receive, by means of certain of these converging fibers, sensory impressions from other parts, as the normal perception of external objects is sometimes destroyed ; while we also know that, in the same type of cases, motor impulses are often de- stroyed, thus proving that motor fibers are also included among those which pass through the internal capsule or the basal ganglia. I think it can be, therefore, safely stated that the association between the gray matter of the cerebrum and both the motor and sensory nerve fibers is considered as proven, although some doubt may still exist as to the precise course of these fibers. Fig. 11, — Diagrammatic representation of the fibers in the cerehrrim. (Le Bon.) FuiN^CTioNS OF THE Cerebrum. — At the present day we 'e in possession of a sufficient number of facts, derived from 28 THE BRAIN. clinical observation, pathological research, and experimental investigation, to render it certain that no intelligence can ex- ist without brain substance ; that the destruction of brain substance impairs intellectual power; and that the normal use of the brain implies a degeneration of its substance and a constant process of regeneration, as exists in all tissues. It was formerly supposed that the cerebrum was destitute of both sensation and irritability, since experiments seemed to show that no pain was experienced by removal of portions of the hemispheres, nor convulsive movements produced by dii'ect stimulation of either the white or gray matter. It has there- fore been claimed that the hemispheres could be called into action only in response to a sensory impression transmitted to its cells through sensory nerves, and that it was incapable of transmitting or appreciating artificial forms of stimulation. In 1870, however, Fritsch ' and Hitzig ^ discovered that certain parts of the gray matter of the hemispheres of the brain of a dog responded to a weak galvanic current, and these investi- gators were thus enabled to locate centers where certain well- defined movements could be produced at will. These experi- menters found (1) that the centers of motion were always confined to the anterior parts of the hemisphere ; (2), that the action on muscles was a crossed action^^ i. e., on the side opposite to the stimulation ; and (3), that, after severe haemor- rhage, the excitability of the gray matter disappeared,, thus possibly accounting for the negative results of previous ex- perimenters in the same line. The centers of motion discovered by these experiments seemed to be connected with parts which were widely sepa- rated, and arranged with little apparent system ; thus the muscles of the neck were found to respond to galvanism of a center in the middle of the frontal convolution, while the cen- ' Reichardt u. du Bois-Raymond's " Archiv," 1870. Mlitzig, "Das Gchirn," 1874. ' Bro\vn-S6quard has shown that, in exceptional eases, this law may be not sustained by clinical facts. " Lancet," 1876. The anatomical researches of Flechsig, however, tend to explain the exceptions to the general rule (sec pages of this volume referring to the fibers of the medulla oblongata). THE HEMISPHERES, 29 rer adjoining it caused a response in the extensor and abduc- tor muscles of the fore-leg, and others in movements of the eye and face. Ferrier' has of late repeated and confirmed i\\e experiments of these German investigators/ The effects of removal of the cerebral hemispheres of ani- mals have been studied largely upon birds and the monkey tribe, and with results which are comparatively uniform. Without entering into detail as to all the effects which follow such a procedure, in case the basal ganglia are left intact, the o-eneral result may be given as follows : The animal seems to be able to execute all the movements natural to it, even when (^omplex coordination of movement is required ; but the intel- ligence seems to be impaired, and some unusual stimulus must be present to prompt any attempts at motion. As a result of this conclusion, the mechanism of coordination of movement is evidently not situated in the cerebral hemispheres. Flourens,' from a series of experiments made in 1822 and 1823, concluded that the removal of the cerebrum entailed an entire loss of will power and also of the perceptive faculty, and that the memory was utterly destroyed. Bouillaud,* in 1826, proved the error of Flourens as regards the perceptive faculties, as sight and hearing were shown to be unaffected ; and these results were still further made manifest by the re- searches of Longet,' who proved also that taste remained. A careful study of the phenomena which accompany cer- tain pathological lesions of the brain in the human subject, such as laceration or pressure from the effusion of blood, soft- ening of the cerebral substance, etc., if taken in connection with the results of experiments upon living animals, throws considerable light upon the functions of certain distinct por- tions of the encephalon. ' "West Riding Reports," 1873 ; " Functions of the Brain," 1876. ^ A large number of distinct centers of motion are mapped out by this author on a diagrammatic chart. The reader is referred to Fig. 15 of this volume. ^"Rocherches experimentales sur les proprietes et les fonctionsdu systemc nerveux,'* Paris, 1842. * " Recherches experimentales sur les fonctions du cerveau." ^ "Anatomic et physiologic du systeme nerveux," Paris, 1842. 30 THE BRAIN. HcBmorrhage within the brain substance most commonly affects the corpus striatum or the optic tJialamus ; and it is now considered probable that, when the former ganglion is pressed upon, paralysis of motion^ limited to the side of the body opposite to the lesion, is present, while, if the latter ganglion is pressed upon or destroyed, the sensation of the side of the body opposite to the lesion is proportionally impaired.' These facts illustrate the general course of both the motor and sensory fibers through the cerebrum, and their relation to the basal ganglia or the internal capsule. In those exceptional cases of haemorrhage where the white or the gray substance of the cerebral hemispheres is alone involved, without any pressure being exerted upon the basal ganglia or the internal capsule, no paralysis of either motion or sensation is usually produced, although a certain amount of weakness may often be perceived in the muscles of the side of the body opposite to the seat of the haemorrhage. Softening of the cerebral hemispheres and the degenera- tive changes which often follow an extravasation of blood into their substance are generally indicated by alterations in the intellectual condition of the patient, thus confirming the physiological experiments upon the hemispheres. Among the many forms in which this impairment of intellect may be manifested are recognized an impairment of memory ; a tardy, inaccurate, and feeble connection of ideas ; an irritabili- ty of temper, with a childish susceptibility to petty or imagi- nary annoyances ; easily excited emotional manifestations ; and a variety of phenomena denoting abnormally feeble in- tellectual power.' Hughlings- Jackson ' has shown that there is clear evidence to prove that disease of the gray matter of the convolutions of the hemispheres of the cerebrum may not only produce de- lirium^ as in meningitis, but sometimes convulsioiis. either of * This effect on sensation and motion is explained by some authors as tlie result of pressure upon the fibers of the intci'nal capsule, and not the fibers of the basal ganglia. ' A. Flint, Jr., op. cit. » "London Hosp. Reports," 18G4 ; " Clin, and Phys. Researches," 1873. CENTERS OF MOTION 31 an epileptiform character or confined to particular groups of muscles. Landois ' and Hitzig ' both announced the fact that, when the motor areas upon the convex surface of the cerebrum, Fig. 12. — A diagrammatic fgure, showing the cerebral convolutions. (After Dalton.) S, Fissure of Sylvius, with its two branches a and h, b, b ; R, fissure of Rolando ; P, pa- rieto-occipital fissure; 1, 1, 1, the first or superior frontal convolution; 2, 2, 2, 2, the second or middle frontal convolution ; 3, 3, 3, the third frontal convolution, curving around the ascending limb of the fissure of Sylvius {center of speech) ; 4, 4, 4, ascending frontal (anterior central) convolution ; 5, 5, 5, ascending parietal (pos- terior central) convolution ; 6, 6, 6, supra-Sylvian convolution (parietal lobule), which is continuous with 7, 7, 7, the first or superior temporal convolution ; 8, 8, 8, the angular convolution (or gyrus), the probable center of vision^ which becomes continuous with 9, 9, 9, the middle temporal convolution; 10, the third or in- ferior temporal convolution ; 11, 11, the superior parietal (supra-marginal) convo- lution; 12, 12, 12, the superior, middle, and inferior occipital convolutions (called also the first, second, and third). It is to be remembered that the term " gyrus " is synonymous with convolution," and that both terms are often interchanged. This cut may well be compared with that of Ferrier, which appears in the general sum- mary of the clinical points of the brain. which control the movements of the extremities, are excised, ^rise in the temperature of the corresponding limbs takes Virchow's "Archiv," 1876. As quoted by Foster. 32 TEE BRAIN. place and lasts for some months. A relationship has, more- over, been observed between the brain cortex and the beat of the heart (Balogh ') ; an alteration in the arterial pressure (Bochefontaine ') ; contraction of the bladder, spleen, and uterus ; an increase in the flow of the saliva ; and a dilating effect upon the pupil. The exact localization of some of these latter centers can not, as yet, be considered as positive. Stimulation of the cerebral surface has been observed to result in a well-marked hcemorrhage of the lungs by Noth- nagel.' Ferrier* describes a ''msuaV center, the destruction of which creates blindness of the opi)osite eye ; an "-auditory" center; a ''tactile''^ center; centers for smell and taste; and even a center for the sensation of hunger. The center of articulate speech is perhaps one of the most definitely settled points in cerebral localization ; and this is all the more interesting, since this is the only sharply defined faculty which has, as yet, been definitely localized.' There are two forms of aphasia, which are clinically recognized, viz., the amnesic and the ataxic varieties. In the former, the m^emory of words is utterly lost, so that the patient is not only unable to express his ideas in articulate sounds, but he is also unable to write them, thus showing that the words them- selves have been forgotten. In the ataxic variety, however, the memory of words still remains, but the ability to so coordi- nate the muscles of articulation as to pronounce the words is impaired, so that the person so afflicted can vrrite his ideas intelligently, but can not utter them. In either of these con- ditions, the disease which causes it must affect the center of the muscles of articulate speech or the center of articulate speech itself. It is not to be confounded, however, with other diseases where the ability to talk is apparently absent, such as occurs in the insane (who often refuse to converse from mere obstinacy), in those types of paralysis which affect ' Hofmann und Schwalbe's " Bericht," 1876. "^ " Archives dc Physiol.," 1876. 3 "Cbl. med. Wiss.," 1874. ■• Op. cit. ' Some late authors refuse their concurrence with this statement, as several cases have*^ been reported which tend to justify a doubt as to its accuracy. CENTER OF SPEECH. 33 the entire muscular mechanism associated with articulation, in hysteria, chorea, and nervous affections, and in the apho- nia of laryngeal inflammation or paralysis. The credit of the great discovery that the center of articu- late speech could be localized in the third convolution of the left anterior lohe of the cerebrum is generally awarded to Fig. 13. — Structure of the convolutions. (After Baillarger.) 1, the six alternate gray and white layers in the cortical substance of the convolutions; 2, enlarged section of a convolution — the left half is seen by reflected light — layers arranged as in the preceding figure — in the right half, seen by transmitted light, the medullary layers are rendered dark by their opacity — the layers of gray substance, on the other hand, which are translucent, are represented in white ; 3, section of a con- volution showing the unequal thickness of the white layers — at first sight only three layers can be distinguished, two gray and an intervening white layer — more attentive examination shows six layers, the superficial and deep white layers being, however, very narrow ; 4, section of a convolution showing the three layers of gray matter observed by Vicq d'Azyr in the occipital lobe ; 5, tendency to radiation shown by the white fibers in the gray matter of the convolutions ; 6, section of a cerebral convolu- tion in a newly born infant, seen by reflected light — it presents an homogeneous appearance ; 7, same section seen by transmitted light — presents the same stratifica- tion and tendency to radiation which are observed in the adult. Broca.' Some twenty-five years before he made the profession alive to the investigation of the subject, however, the same impairment or loss of speech was shown to be a frequent accompaniment of hemiplegia of the right side of the body by Bouillaud and Marc Dax ' ; and in 1863, or thereabout, the I J Broca, "Bui. de la Soc. Anat.," 1861. ' A paper read before the Medical Congress at I^Iontpellier in 1836. 34 THE BRAIN. views of Broca and of Hughlings- Jackson ' were given to the profession, in which they both limited the lesion of aphasia to the parts supplied by the left middle cerebral artery. In 1863, the investigations also of the son of Marc Dax " located the lesion somewhere in the anterior or middle portion of the frontal lohe of the left side, and the results of still more recent investigations upon the subject seem to point to the "island of Reil" as the most frequent seat of this peculiar type of paralysis. Viewing the fact that articulate speech is a thing learned by use, it has been suggested that, in most persons, one side of the brain only has been educated for that purpose ; that we are, in fact, left-hrained in respect to speech in the same way that we are right-handed in respect to many bodily movements."* In support of this theory the pathological fact is adduced that, in most people, the left hemisphere of the cerebrum is larger and more convoluted than the right. While it is demonstrated that the cerebral lesion in apha- sia involves, in the great majority of cases, the left side, still there have been several cases recorded where the right side has been shown to have been the seat of disease.* Such dis- coveries tend to cast a doubt upon the left side being more closely connected with the power of articulate speech than the right side, and some anatomists have endeavored to explain the frequency of the lesion upon the left side of the brain as a result of the fact that emboli (which are the most frequent cause of the disturbance to those parts supplied by the middle cerebral artery) find a much more direct course upward upon the left side than upon the right, in consequence of the angle at which the innominate artery leaves the arch of the aorta, which favors the passage of an embolus hy rather than into its mouth ; while the left carotid artery is situated at the ' Hughlings-Jackson, " Clinical and Physiological Researches on the Nervous Sys- tem." ' M. G. Dax, as quoted by Dodds and A. Flint, Jr. ' Mich. Foster, op. cif. ; Ferrier, " Functions of the Brain." * Boyd, Broadbent, Bateman, Meissner, Bertin. THE FRONTAL LOBES. 35 highest part of the arch, and its mouth is so directed as to arrest rather than avoid any floating particles in the blood current. In case of such movable particles being arrested either by the innominate or left carotid arteries, the most direct course in both instances will be toward the middle cere- bral arteries, and thus aphasia will generally be produced with hemiplegia upon the side opposite to that where the embolus may be found. The Frontal Lobes. — There are innumerable cases on record where the frontal lobes of the cerebrum have suffered MEDULLA Fig. U. — Diagram of the course of sensory arid motor tracts in the meso-cephalon and hemispheres. (After Seguin.) S, sensory tract in posterior region of meso-cephalon, extending to and T, occipital and temporal lobes of hemispheres ; M, motor tract in basis cruris, extending to P and F, parietal and (part of) frontal lobes of hemispheres ; C, Q, corpus quadrigemi- HL num ; 0, T, optic thalamus ; N, L, nucleus Icnticularis ; N, C, nucleus caudatus ; 1, IH the fibers forming the " tegmentum cruris " (Meynert) ; 2, the fibers forming the ■■[ " basis cruris " (Meynert). ^frightful lacerations and loss of substance, and yet recovery \ has taken place ; and where disease of an extensive character I has also produced negative results, both as regards motion and sensation. 36 THE BRAIN. A crowbar has been shot through the head, and recovery followed. ' Again, Bouillaud ' reports the passage of a bullet through the frontal lobes with a like result, and with no effect upon sensation or motion. Cases, somewhat similar, are re- corded by Trousseau,' Congreve, Selwyn,* Pitres," Morgagni, Marot," Tavignot, and others, all of which go to x^rove the pos- sibility of the most serious injury to this portion of the cere- brum without symptoms indicative of its presence. On the other hand, numerous cases of haemorrhage and of abscess within the frontal lobes, as reported by Andral,' Hertz, Reed, Begbie, and others (quoted by Charcot and Ferrier), show the same absence of positive diagnostic symptoms either in sen- sory or motor paralysis. From such sources of clinical reasoning, as well as from the physiological deductions which experiments upon animals have taught, the following conclusion of Ferrier * is of value to the reader : '' With such evidence before us, we can not regard cases, in which, with lesions of the prsefrontal lobes, sensation or motion has been affected, as other than cases of coexistence or of multiple lesions, whether organic or functional." THE MOTOR REGIONS OF THE CEREBRUM." It may now be positively stated that the bases of the three frontal convolutions, the convolutions which bound the fis- ^ Bigelow, "Am. Jour, of Med. Sciences," July, 1850; Harlow, "Recovery from the Passage of an Iron Bar through the Head " ; " Reports of Mass. Med. Soc," Boston, 1869. 2 Op. cit. 2 Quoted by Peter and Ferrier. 4 London " Lancet," 183 S. ^ " Lesions du Centre Ovale," 1877. « "Prog. M6d.," February and June, 1876. ' " Clinique M6dicale." " "Localization of Cerebral Disease," New York, 1880. ® Microscopic anatomy shows that the so-called motor gyri are rich ^in large cells ; that they alone contain the "giant cells" of Betz (" Centralblatt," Nos. 37, 38), viz., ganglion cells, which in size and number of processes bear a remarkable resemblance to the unquestionably motor ganglion cells of the anterior horns of the spinal cord and the medulla oblongata. In the motor convolutions these giant cells are found in little clus- ters of three, five, or more, in a section, imbedded among the large ganglion cells of the third layer. TEE MOTOR AREA. 37 Hwre of Rolando^ and Xh^ para-central lobule^ upon the inter- nal surface of each hemisphere of the cerebrum, are distinctly motor in their function. The distribution of the middle cere- l)ral artery to this region gives to that vessel an importance not before appreciated ; since it is now known that the four or five branches which are given oif from the main artery each nourish a separate area of brain substance, and that emboli may obstruct either the trunk or some of its in- dividual branches. It is thus possible to explain how the basal ganglia may still perform their functions while other parts giipplied by some of the cortical branches may be im- ])aired. The preponderance of clinical testimony goes to show that most of the destructive lesions which are associated during life with paralysis of voluntary motion are con- fined to this motor area, although a rare case is on re- cord ' where the motor area was the seat of cystic disease, and still voluntary motion remained unaffected. It is a matter of great doubt whether the gray matter of the con- \'olutions was impaired, even in this case, in spite of the existing lesion. The effect of extensive lesions affecting the motor area of the monkey (which is commonly used for experiments, as the nearest approach to the type of mankind) may be summarized as follows: 1. A hemiplegia, which is at first absolute ; 2. An improvement in associate, alternating, or bilateral movements, but no improvement in voluntary mo- tion. Respecting this point, I quote from a late work as fol- lows: ''As examples of the improvement which follows the on- I'l set of the hemiplegia, the hand becomes more paralyzed than the arm, the arm more than the leg, and the lower facial movements more than the upper; while the muscles of the I trunk are scarcely, if at all, affected." ' li ^ Samt, "Archiv fur Psychiatric," 1S74. ' Ferrier, '' Localization of Cerebral Disease. 38 THE BRAIK In man the hemiplegia is usually on the side opposite to the existing lesion/ if the motor area, the corpus striatum, or the anterior part of the internal capsule be the seat of disease ; and this paralysis is often accompanied by con- vulsive muscular movements or rigidity of the paralyzed parts, in its early stage, and, later on, by rigidity and motor sclerosis.'' The researches of Pitres ' have shown that the same re- sults as those dependent upon a lesion of the gray matter of the convolutions within the motor area follow when the lesion affects the white substance of the brain* which intervenes between the gray matter covering the motor area and the basal ganglia beneath them, and he thus urges a system of nomen- clature of the different portions of the ''centrum ovale" by means of sections of the brain made in certain regions so as to show special parts. It is by means of these researches that we are enabled to explain those cases where rigidity or muscular spasms accom- pany an* attack of hemiplegia, from an effusion into the lateral ventricles of the brain ; and where cerebral soft- ening or hcemorrhage^ which does not affect the gray mat- ter of the convolutions or the basal ganglia, produces a jDer- manent paralysis of the side of the body opposite to the lesion. When sudden hemiplegia occurs, as a result of haemor- rhage into or traumatism of some portion of the motor area, the condition of paralysis is liable to improve in those re- gions of the body where the special motor center of that part remains unimpaired, but the paralysis will usually remain permanent in that part of the body whose motor center is destroyed. This fact, when properly interpreted, may often prove a most valuable guide in diagnosis. ' The fact that all the motor fibers do not decussate in the medulla oblongata (Flech- sig) explains the exceptions to this rule. ' See later pages of this volume for further explanation of this point and its clinical interest. ' "Lesions du Centre Ovale," Paris, 1877. * This portion contains the fibers of the into-nal capsule radiating to reach the motor regions of the cortex. (See Fig. 8.) THE MOTOR AREA, 39 Special Centers of Motion. — At the base of the first fron- tal convolution^ and extending slightly into the second fron- I'lG. 15. — Sid? vieio of the brain of man and the areas of the cerebral convolutions. (After Ferrier.) (on the postero-parietal [superior parietal] lobule), advance of the opposite hind-limb as in walking ; 2, 8, 4 (around the upper extremity of the fissure of Rolando), com- plex movements of the opposite leg and arm, and of the trunk, as in swimming ; rt, 6, c, d (on the postero-parietal [posterior central] convolution), individual and combined movements of the fingers and wrist of the opposite hand : prehensile move- ments ; 5 (at the posterior extremity of the superior frontal convolution), extension forward of the opposite arm and hand ; 6 (on the upper part of the antero-parietal or ascending frontal [anterior central] convolution), supination and flexion of the opposite fore-arm ; 7 (on the median portion of the same convolution), retraction and elevation of the opposite angle of the mouth by means of the zygomatic muscles ; 8 (lower down on the same convolution), elevation of the ala nasi and upper lip with depression of the lower lip, on the opposite side ; 9, 10 (at the inferior extremity of the same convolution, Broca's convolution), opening of the mouth with 9, protrusion, and 10, retraction of the tongue — region of aphasia, bilateral action; 11 (between 10 and the inferior extremity of the postero-parietal convolution), retraction of the opposite angle of the mouth, the head turned slightly to one side ; 12 (on the poste- rior portions of the superior and middle frontal convolutions), the eyes open widely, the pupils dilate, and the head and eyes turn toward the opposite side ; 13, 13 (on the supra-marginal lobule and angular gyrus), the eyes move toward the opposite side with an upward 13, or downward 13* deviation ; the pupils generally contracted (cen- ter of vision) ; 14 (of the infra-marginal, or superior [first] temporo-sphenoidal con- volution), pricking of the opposite ear, the head and eyes turn to the opposite side, and the pupils dilate largely (center of hearing). Ferrier, moreover, places the cen- ters of taste and smell at the extremity of the temporo-sphenoidal lobe, and that of touch in the gyrus uncinatus and hippocampus major. 40 TEE BRAIK tal convolution^ in the brain of a monkey may be located a distinct center which exerts a special influence upon the head and eyes. Thus, to qiiote from Ferrier, whose researches have been remarkable for their originality and apparent accu- i*acy, stimulation of this center causes ' ' elevation of the eye- lids^ dilatation of the pupils^ conjugate deviation of iJie eyes^ and turning of the head toward the opposite side^ (See JSTo. 12 in Fig. 15.) That this same center seems to exist in the human brain is to be inferred from the cases where a h Hater al deviation of the eyes has been observed, w^hich, in some cases, has also been associated with a lateral deflection of the head. Tliis subject has excited the interest of Hughlings- Jackson, ' Priest ley Smith," Ferrier,' and Charcot,* and cases which seem to sustain the theory of an oculo-motor function in the frontal convolutions have been reported by Chouppe, Landouzy,' Carroll, Smith, and others. An effort has been made to ex- plain these ocular symptoms by some association with the angular gyrus (see page 52), but apparently without much ground. The center of motion for the muscles of the limbs is not yet as positively ascertained as the oculo-motor center, al- though some interesting experiments have been made to de- cide whether the corresponding point of the brain of man is analogous, in its control over the leg, to that of the monkey tribe. As an example of the ingenuity shown in research, Bourdon" has endeavored to demonstrate atrophy of certain parts of the brain after amputation of the limbs, and thus indirectly to prove the normal use of the parts which had atrophied from disuse. The use to which the monkey puts his tail, since it serves the purpose of an additional hand in some instances, renders the application of movements of that ' "Ophthalmology in its Relations to General Medicine," "Lancet," 1877. " "Bilateral Deviations of the Eyes," "Birmingham Med. Beview," 1875. » Op. cit. • Op. cit, • " BlC-pharoptose cer6bralc," " Arch. Gen. de MedV 1877. • " Recherches cliniques sur les centres moteurs," Paris, 1877. SPECIAL CENTERS OF MOTION, 41 Pig. 16. — Upper view of the brain of man. and tJve situation of areas of live cei'^ral con- volutions. (After Ferrier.) I (on the postero-parietal [superior parietal] lobule), advance of the opposite hind- limb as in walking; 2, a, 4 (around the upper extremity of the fissure of Rolando), complex movements of the opposite leg and arm, and of the trunk, as in swim- ming ; a, b, c, d (on the postero-parietal [posterior central] convolution), indi- vidual and combined movements of the fingers and wrist of the opposite hand ; pre- nsile movements ; 5 (at the posterior extremity of the superior frontal convolu- n), extension forward of the opposite arm and hand ; 6 (on the upper part of antero parietal or ascending frontal [anterior central] convolution), supination d flexion of the opposite forearm ; 7 (on the median portion of the same con- lution), retraction and elevation of the opposite angle of the mouth by means of zygomatic muscles ; 8 (lower down on the same convolution), elevation of e ala nasi and upper lip with depression of the lower lip, on the opposite side ; 9, (at the inferior extremity of the same convolution, Broca's convolution), open- ^ of the mouth with 9, protrusion, and 10, retraction of the tongue — region of hasia, bilateral action; 11 (between 10 and the inferior extremity of the pos- parietal convolution), retraction of the opposite angle of the mouth, the head med slightly to one side ; 12 (on the posterior portions of the superior and mid- le frontal convolutions), the eyes open widely, the pupils dilate, and the head and «s turn toward the opposite side ; 13, 13 (on the supra-marginal lobule and an- lar gyrus), the eyes move toward the opposite side with an upward 13, or down- rd 13- deviation — the pupils generally contracted (center of vision) ; 14 (of e infra-marginal, or superior [first] temporo-sphenoidal convolution), pricking of e opposite ear, the head and eyes turn to the opposite side, and the pupils dilate anrely (center of hearing). Ferrier, moreover, places the centers of taste and smell at the extremity of the temporo-sphenoidal lobe, and that of touch in the gyrus un- cinatus and hippocampus major. 42 TEE BRAIN. organ to those of man a matter of apparent difficulty, and the center of motion for the tail of the monkey can hardly be applied to the brain of man without bringing comparative anatomy into prominence. Paralysis of the leg, when dependent solely upon cerebral lesions, is seldom separated from a similar condition of the upper extremity, although a few rare cases of that character are on record ; but the rule of Lucas Championniere may be considered as approximately correct, viz., that, to expose the center of motion for the muscles of the leg, it is necessary to trephine over the upper extremity of the fissure of Rolando ."^ The centers of motion for the muscles of the different re- gions of the upper extremity occupy a much larger space upon the surface of the cerebrum than those of the lower ex- tremity, as might have been expected when we consider the amount of intelligence which the hand exhibits.' Ferrier has pointed out certain motor areas for the various move- ments of extension, adduction and retraction, supination and flexion, and centers for the actions of the wrist and finger muscles.' The close proximity of those centers which control the/a- cial and oral muscles to the centers governing the motions of the hand possibly explains why movements of retraction of the mouth occur when the hand is brought into powerful action ; and also the fact that paralysis of certain groups of muscles situated in the upper extremity are commonly asso- ciated with some form of facial paralysis. From a careful analysis of cases where paralysis of the up- per extremity was confined to certain sets of muscles, the re- sults seem to point to the ascending parietal and the upper ' For the surgical guide to locate the situation of that fissure upon the exterior sin- faee of the skull of a living subject, the reader is referred to a subsequent page of this chapter. » Sir Charles Bell, " The Human Hand." ' In pages 39 and 41 of this volume, the centers of Ferrier are shown in a dia- grammatic cut, and the special action of each given in the descriptive text which accom- panies it. SPECIAL CENTERS OF MOTION. 43 loortion of the ascending frontal convolutions of the cere- brum, as the probable seat of disease ; and lesions of the ascending parietal convolution are found, both by experi- mental research and by pathological deduction, to affect the hand in particular. In further support of this state- ment, the results of the examination of the brains of per- sons who had suffered amputation of the hand, ' or who had been characterized by a congenital absence of that member,'' show an atrophy of the part designated by the experiments of Ferrier as the motor center for its move- ments. The motor centers of th.^ facial muscles occupy a region in close proximity to those of the arm and hand ; and it is an exception to the general rule to observe paralysis confined exclusively to the face, since the muscles of some part of the upper extremity are generally affected simultaneously. It may be also noticed, with some degree of practical interest, that aphasia is a common associate of either of these types of local- ized paralysis, since the center of Broca is liable to be also in- volved from its close relation to both the centers of the face, arm, and hand.' It is considered by some authorities that the absence of aphasia, in cases where the muscles of the face, arm, or hand are paralyzed, is probably confined to lesions affecting only the right side of the cerebrum. The lesions in which aphasia exists have been considered somewhat at length in previous pages of this chapter, but the fact that most of the clinical cases recorded have failed thus far to overthrow the discovery of Broca * seems to place it upon a footing above that of mere empirical generalization. Cases have been reported where aphasia has been the result of frac- ture of the left side of the skull in the region of the frontal lobes,' and also where recovery of the power of speech fol- ^ Reported by Bourdon, " Centres moteurs des membres." Paris, 1877. 2 Gowers, article in "Brain,*' 1878. 3 See the relation of the facial centers, Nos. 7, 8, 11, to those of the arm and hand, Nos. 4, 5, 6, a, 6, c, d, and to the oro-lingual centers, Nos. 9, 10, in Fig. 15 of this yolumc. ^ Some late observations apparently point to other centers, as associated with speech, besides that of Broca. ^ Mac Cormac, " Brain," 1877. U THE BRAIN. lowed the operation of trephining,' but it occurs most fre- quently as the result of embolic obstruction of the middle cerebral artery or of some of its branches." Diagnosis of Cortical Motor Paralysis. — The effects of lesions which involve the corpus striatum of either side, or the anterior two thirds of the internal capsule of the cere- brum, differ but little from those of lesions which are confined to the motor area of the cerebral convolutions, since the fibers which are affected in either case are the same." After the effects of the shock of the attack have passed away, the muscles which are paralyzed are usually those which are the most completely under the control of voli- tion; thus the lower muscles of the face are more affected than those upon the forehead or of the eyelids, since the lower facial muscles are by far the most voluntary ; the muscles of the hand are very markedly affected, even more than those of the arm ; and the muscles of the upper extremity more than those of the lower.* No evidence of impairment of sensation can be discovered, provided that the posterior third of the internal capsule of the cerebrum has escaped injury. The nutrition of the para- lyzed muscles is apparently normal, and their electric con- tractility is not impaired. A tendency toward rigidity of the paralyzed muscles de- velops, later on in the disease, which has been variously ex- plained by some authors (Charcot, Bastian, and Bouchard) as the result of a progressive sclerosis., which descends along the motor tract of the pons Varolii, crus cerebri, medulla, and the spinal cord ; while the researches of Hughlings- Jackson ' ^ Terrillon and Proust, "Acad, do Medicine," ISYG. ' See researches of Meissner, Charcot, Vulpian, Seguin, Bertin, and others. * Ferrier, op. cit. The reader is referred to Fig. 8 of this volume, in explanation of this statement. ^ Pathological anatomy (recent cases) demonstrates: 1, that destructive lesions of the motor regions of the cortex (and of the para-central lobule) produce descending degenera- tion throughout the direct cerebral motor tract, extending into the lateral columns of the spinal cord ; and 2, that there is a remarkable correspondence between certain localized spasmodic and paralytic symptoms observed during life and lesions irritating or destroy- ing certain definite spots in the motor zone of the cortex. " " Medical Examiner," April, 1877. I TYPES OF MONOPLEGIA. 45 warrants Mm in discarding this explanation and attributing it to an unimpeded cerebellar influence., whicli is no longer controlled by the cerebrum. Both of these hypotheses are, however, discarded by Buret,' who considers the rigidity to be the result of simple reflex irritation. It will in no way add to the practicability of the matter contained here to enter into the discussion of the relative demerits of these theories, since those interested in the subject will find Ter- rier's work on the ''Localization of Cerebral Disease" and many of the advanced works upon the pathology of dis- eases of the nervous system to contain all the desired infor- mation. One of the most valuable signs of paralysis dependent upon a lesion of the cortex is the fact that the condition is not one of complete hemiplegia, but rather of monoplegia, in which special groups of muscles only are deprived of voluntary motion : thus, the arm and leg may be affected together ; again, the arm, hand, and face ; the arm alone ; the leg alone ; cer- tain movements only of either extremity ; and all other possi- ble combinations. Paralysis due to lesions of the cortex may often be transitory, if the lesion be slight and superficial ; or it may be permanent, if deep and impinging upon the medulla. It is, furthermore, frequently associated with rigidity in its early stages, which is a rare occurrence in central cerebral disease. In attacks of paralysis due to suddenly developed lesions of the cortex, consciousness is less frequently lost than in similar lesions of the central ganglia, and pain of a local char- acter within the head is often either complained of by the pa- tient spontaneously with the attack, or it may be sometimes elicited by percussion over the seat of the exciting lesion. The loss of consciousness which generally accompanies any sudden lesion of the central ganglia is explained by Bu- ret ' as due to a rapid displacement of the cerebrospinal fluid, which in turn creates a general disturbance of the cir- ^ "Brain," Parti, 18VY. * " Traumatismes cercbraux," Th^se, 1878; "Archiv. de Physiologic," ISYS. 46 THE BRAIN. culation of the cerebrum, since this fluid serves to establish a uniformity of pressure throughout the brain. Ferrier ' thus briefly summarizes the results of clinical ob- servation bearing upon the diagnosis of paralysis dependent upon destructive lesions of the cortex: '^ While we can not be quite certain of the position or extent of a cortical lesion causing a sudden and complete hemiplegia, we may take a monoplegia of the leg, or of the arm and leg, as an indication of a lesion of the upper extremity of the ascending convolu- tions close to the longitudinal fissure ; brachial monoplegia, as a sign of a lesion in the upper part of the ascending fron- tal convolution, or, if the paralysis affect tlie hand more particularly, of the ascending parietal convolution ; hrachio- facial monoplegia, as indicating a lesion of the mid-fronto- parietal region ; while /acm? and lingual monoplegia, or this combined with aphasia, indicates a lesion of the lower part of the ascending frontal convolution where the third frontal joins with it." '^ Irritative Lesions of the Motor Area. — It is a well-recog- nized fact in clinical experience that certain symptoms, which are chiefly of a convulsive type, are dependent upon conditions which create simply irritation of certain portions of the cere- brum, without any actual destruction of the gray or w^hite matter. Among the various conditions which are esjiecially liable to produce such local irritation may be mentioned syphilitic meningo-encephalitis, simple inflammation of the same character, deposit of tubercle, superflcial cysts or tu- mors of a more solid character, spiculae of bone, cicatrices from wounds of previous date, suppuration from caries and necrosis, etc. In the year 1867,' and still later, in the year 1871,* the general statement by which the clinical diagnosis of the situa- tion of irritative lesions of the cerebrum might be assisted was ' Op. cit. ' The plate showing the motor centers will tend to explain these deductions. Sec page 39 of this volume. 3 " St. Bartholomew's Hospital Reports." * " Medico-Chir. Trans." JACKSOmAN EPILEPSY. 4Y advanced by Callender, "that convulsive attacks were most commonly associated with superficial lesions of the cortex sit- uated in the immediate vicinity of the middle meningeal ar- tery." Ferrier, however, concludes, as the result of his exten- sive facilities for observation, that, while this may be useful as a general rule, still any portion of the cortex of the hemi- sphere may result in convulsions of the opposite side of the body, and he adds the statement that the seat of an irritative lesion can be less accurately determined than one of a destruc- tive character, owing to the difficulty of determining the ex- tent of the zone in which vital irritation concentrates itself. Hughlings- Jackson ' has contributed much to the pathology of those conditions of the cortex, produced by irritation, which manifest themselves in the form of convulsions. So great a prominence did syphilis have as one of the exciting causes of such irritation that the term ''Jacksonian epilepsy " is now often used as synonymous with the convulsions met with in that disease. The theory which this author advances to ex- plain these convulsive attacks is as follows : That irritation of the cortex tends toward an abnormal accumulation of ner- vous energy, so that the aft'ected part is under a state of high tension, and, under certain conditions, this irritated portion discharges itself in a sudden and explosive manner, thus pro- ducing a subsequent exhaustion of its powers ; hence a con- vulsion, and often some type of monoplegia following it. The convulsions dependent upon irritation of the cortex may assume all of the diiferent varieties produced by de- structive lesions of the motor area, and may even result in paralysis ; thus the leg may alone be affected with spasm, the arm alone, the arm and hand together, and the face alone, or in connection with the upper extremity. It may often assist in the localization of a lesion, which is creating the irritation of the cortex, to note carefully the mus- cles affected at the onset of the convulsion, since they may enable the observer, through a knowledge of the motor cen- ters, to trace the seat of the region within the cortex which ^ Oj). cit. Also see "Medical Times and Gazette," ISVS. 48 THE BRAIN. first exhibited a tendency to explosive discharge of its nerv- ous energy. THE SENSORY REGIONS OF THE CEREBRUM. The temporo-sphenoidal and occipital lobes of the cerebrum are now accepted by most authors as the only portions which can appreciate the perception of sensory impressions. This fact seems to be demonstrated not only by experimental in- vestigation upon animals, but also by clinical observation, with as great a degree of certainty as previous facts which have been mentioned regarding the function of the frontal region and the motor area. It has been determined, with some approach to positive- ness of statement, that the posterior fibers of the cms are the principal means of transmission of sensory impressions from the periphery of the body to the cerebrum, and the researches of Meynert have done much to demonstrate that these fibers are connected with the portions of the cortex which have been designated as the regions chiefly associated with sensory perception. Duret,' Veyssiere," and Raymond have shown by experi- ment that, when that part of the internal capsule which is situated between the lenticular nucleus and the optic thala- mus is divided, a loss of sensation is experienced in the oppo- site side of the body, but that, in some instances, some degree of motor paralysis is also produced. On the other hand, these same observers have found that section of the anterior two thirds of the internal capsule produces a distinct motor paralysis, with no effect upon the function of sensory percep- tion of the parts paralyzed, save in a few instances, where such a result of a fleeting character was detected. That these deductions are fully sustained by clinical facts, as fnr as the motor nerves are concerned, the statements of preceding pages seem to clearly prove, and the collected cases ' Op. tit. 3 " Sur rh6mianesth6sie de cause c6r6brale," 1874. THE OCCIPITAL LOBES. 49 reported by Charcot/ Pitres,' Turck/ and others, present a large mass of evidence to warrant the conclusion that lesions of the posterior part of the internal capsule are indicated by hemi-ansesthesia on the side of the body opposite to the lesion. In such cases, tactile sensation is destroyed to the median line not only in the trunk, but also upon the face ; pain and the sensation of heat are likewise abolished ; but the contractility of muscles under the electric current is not im- paired or lost. If we examine the mucous membranes of the eye, nose, or mouth, the same condition of destroyed sensi- bility will be detected, but the viscera remain sensitive. Furthermore, taste, smell, and hearing are usually rendered deficient, and, in some cases, are entirely abolished, on the side opposite to the lesion ; and the special sense of sight is affected in a variety of ways, which will be described in detail. In the admirable work of Charcot, * a diagram is given to ustrate the effect of pressure upon the optic tract, the com- issure, and the optic nerve itself, which I shall use in the scussion of the value of the optic nerve as a guide in diag- osis later in this course ; ' but the clinical facts afforded by sions within the internal capsule fail to support similar re- ults as the effect of intra-cerebral pressure. Thus, in lesions if the internal capsule, blindness of the lateral half of both etinse (?iemianopsia\ as one would expect to find, does not xist ; but, on the contrary, a condition of amblyopia results, rhich is characterized by a marked contraction of the field •f vision, and especially so as regards the perception of color. By consulting the diagram given you in the description of bhe optic nerve," you will perceive that the field for blue tints K the largest, and that red is next in point of size, while f 1 " Lccons sur les maladies du systeme nerveux." f 2 " Lesions du Centre Ovale." 2 See Grasset, "Localizations dans les maladies cerebrales," 1S78. 4 Op. cit. 5 The reader is referred to the diagrammatic cut and its descriptive text in the lecture on the optic nerve. 6 See page of this volume containing a diagram by Hirschberg. 50 TEE BRAIN. green comes last.' Now, in lesions of the internal capsule, the perception of these colors is impaired in the relative pro- portion of the size of the field, and thus green may be en- tirely lost, while the vision of red or blue may still remain. It has been shown by Landolt,'' who has done much to develop this special field of investigation, that the impairment of vision from intra-cerebral causes is not altogether confined to one side, but that the eye upon the same side as the lesion is somewhat affected, and rendered partially anaesthetic. If we examine the eyes so affected, we can not discover by the ophthalmoscope any organic disease or evidences of degeneration of either the optic nerve or the retina, provided that the examination is made early, before any late results of the blind condition of the eye manifest themselves as the effect of disuse." As has been before stated, the condition of amblyopia and the absence of hemianopsia are in opposition to what the ef- fects of pressure upon the optic tracts would seem to suggest, but we still have a clinical fact to explain, viz., that hemi- anopsia does sometimes occur with attacks of hemiplegia. Ferrier states positively that, in such cases as these, we may conclude that the lesion must be either situated below the cerebral cortex, or exert its influence below the cortex, in case it be contained within it. The angular gyrus,* which is now considered as the probable center of vision, does not seem to exert any influence upon the motor apparatus, as is shown by its destruction in animals. The Occipital Lobes of the cerebrum have been stated to be properly included among the sensory regions of the cortex. Experiments of section, or even of complete removal of these lobes of one or both sides, however, fail to show any effect ' Violet has a still smaller field, but it is not shown upon the chart. 2 " La France Medicalc," 1877. 3 Any inter-cranial lesion which acts in such a way as to increase the mtra-cranial presmre may produce (in addition to other symptoms) the condition known as " choked disk," or a neuro-rctinitis. ^ The reader is referred to the lecture on the optic nerve for further information upon this point. THE OCCIPITAL LOBES. 51 upon sensory or motor functions. So negative, indeed, arc these results that no disturbance of taste, hearing, touch, smell, or sight ' has been positively produced. It is from the absence of positive experimental deduction as to these lobes that the distribution of the decussating fibers of the optic tracts to the occipital lobes may be yet considered as ques- tionable, although such an anatomical distribution is stated, by many late authors, "^ to be capable of verification. Certain clinical facts, however, seem to warrant the belief that the occipital lobes are associated with more apparent mental derangement than the frontal or temporo-sphenoidal lobes, in case they be the seat of disease, and the conclusion of FerrierMs thus stated, as an hypothesis: " The occipital lobes are specially related to the visceral sensibilities, and are the anatomical sub- strata of the correlative feelings which form a large portion of our personality and subjectivity." It is claimed by Hughlings- Jackson that irritative lesions of the cipital lobes give rise to colored perception of objects and ther ocular spectra, and he further states that such evidences of defective perception are more common when the lesion affects the right side. The Temporo-spheis^oidal Lobes are situated between the motor area, in front, and the occipital lobe, behind. The fol- lowing deductions have been drawn, by experimental re- search, as to the special functions of this lobe and some of the adjoining convolutions, which will require separate con- sideration : The apparent connection of this region with the special sense of mslon has been noticed by Hitzig, Goltz, and McKen- drick, the two former of whom confined their experiments to the dog species, while the latter operated exclusively upon pigeons. Ferrier,' however, from a belief that other functions could be demonstrated as pertaining to this locality, and from ^ Munk claims to have positively proved an association of the occipital lobe with vis- ion, but his experiments have not, as yet, been fully substantiated. ^ Researches of Fcrrier, Yeo, Dalton, and others. ^ " Localization of Cerebral Disease." * Op. cit. ; Terrier and Yeo, "Brain," 1880 ; Exner, "Brain," October, 1880. Foti 52 THE BBAIK disbelief in the method pursued by Goltz/ as adapted to the requirements of experimental research concerning the func- tions of limited areas of the cortex, made a series of experi- ments upon the brains of monkeys, and claims to have estab- lished some new points of physiological interest, and, possibly, of practical value in cerebral localization. The conclusions which were drawn as the results of the labors of this learned and original investigator may be thus summarized : 1. In the angular gyrus ^ is situated a center, which causes, on electric irritation, certain movements of the eyes, pupils, and head, but whose destruction creates no evidence of motor paralysis in the muscles of either the eye, its lids, or the pupil. Unilateral destruction, however, of this center causes blindness of the opposite eye, which proves but tem- porary ; while the destruction of doth sides causes a perma- nent loss of sight in both eyes." It thus appears that the center of either side is, to some extent, connected with both eyes. 2. In the superior temporo- sphenoidal convolution* is found to exist a center which, under galvanic stimulation, creates a twitching of the opposite ear and a modification in hearing of the opposite side, but which it was found difficult to fully ascertain on account of the animal not being able to exhibit appreciation of modification of that special sense. As in the preceding center, destruction of this convolution, upon one side, caused some abnormality of hearing ; and, when both sides were destroyed, the animal became totally deaf, but no motor paralysis could be discovered in either case. 3. In the lower extremity of the lobe previously desig- nated, a center was found which seemed to exert an influence upon the special sense of smell, and also motions of the nos- • That of trcphininj* over the spot selected for investigation, and washing away the brain by a forcible stream of water. ■'' Regions marked lo in Fig. 15 of this volume. ' The experiments of Munk, Luciani, Tamburini, Ferrier, Yco, Dalton, and others, upon these centers leave the field, as yet, a matter for further investigation. * Sec diagrammatic cut on page 39 of this volume; regions marked 14. THE TEMPOEO'SPHENOIDAL LOBES. 53 tril and head wMcli indicated excitation of that sense. In the regions adjacent to this convohition the special sense of taste became affected when destroyed ; and, when the convo- lution and the adjacent region were destroyed, upon both sides, taste and smell were utterly lost. In regard also to these two centers, unilateral destruction created the most marked effects upon the side opposite to the lesion, while a bilateral destruction abolished the sense altogether. 4. In the region of the Mppocampus some evidence was given of the control over tactile sensation^ but the situation Fig. 17. — A diagram illustrating tlie c^yiirf^e of nerve impulses in the ecrebrum. (After Dodds.) A, the motor regions of the cerebral cortex, represented by arrow-heads ; B, the sensor^/ regions of the cerebral cortex, represented by circles ; C, commissural fibers, con- necting the two regions of the cortex (probable, but not positively demonstrated); D, sensory nerve fibers^ the arrow showing the centripetal direction of the impulse ; E, mok>r 7ierve fibers, the arrow showing the centrifugal direction of the impulse ; C. S, " corpus striatum " (the probable motor ganglion at the base of the cerebrum) ; 0. T, " optic thalamus " (the probable sensory ganglion at the base of the cerebrum) ; 1, a few sensory fibers, possibly connected with the "corpus striatum"; 2, a few motor fibers, possilily connected with the " optic thalamus." of the part rendered experiment upon it difficult, and some- what less positive than those upon the areas previously dis- 1= cussed. a 54 THE BRAIN. It is to be regretted that the conclusions of this author as to the situation of these special centers in the sensory regions of the cerebrum should not be as positively sustained by clin- ical and pathological facts as were the conclusions drawn from experimental research upon the motor area of the brain of the monkey tribe. Ferrier endeavors to explain the dis- crepancy between the facts obtained by experiment and those afforded by disease of the same regions in the human brain, by the hypothesis that the special senses may be governed by a bilateral rather than a unilateral impulse, as the ex- perimental facts pertaining to the special senses of sight and hearing seem to warrant, and this has not, as yet, been dis- proved, since all of the cases recorded have been of a uni- lateral character. To what extent these physiological subdivisions of the sensory area of the cerebrum may be regarded as of prac- tical utility in diagnosis can hardly be determined, as the field is still a new one, and the collection of clinical and pathological records is insufficient for a basis of positive de- duction. THE CORPUS STRIATUM AND OPTIC THALAMUS. These two bodies, which are called the "basal ganglia" of each cerebral hemisphere, are undoubtedly a means of communication between the gray matter of the convolutions and the fibers of the crura cerebri. While it can not be de- nied that some of the fibers of the^ internal capsule are in no way connected with these ganglia, and that a portion of the fibers which pass through them on the way to the convolu- tions are apparently independent of the nerve cells of these ganglia, still the gi-eater proportion of the peduncular fibers of the cerebrum are undoubtedly indirectly connected with the gray matter of the convolutions, being intimately asso- ciated with the nerve cells of wl;ichever of the basal ganglia they are obliged to pass through, in order to reach the ex- terior portions of the hemispheres. t TEE BASAL GANGLIA. 55 It is tlius afRrmed, by many of our later physiologists, that these ganglia act in the capacity of middle-men between the gray matter of the convolutions and the rest of the component parts of the brain, and that they exercise an important influ- ence in mediating between the psychical operations of the cor- tex and the moto-sensory functions of the remaining parts. Fig. 18. — Corpora striata. (Sappey.) 1, fifth ventricle ; 2, the two lamina) of the septum lucidum meeting in front of the fifth ventricle ; 3, hippocampus minor ; 4, posterior portion of the corpus callosum ; 5, middle portion of the fornix ; 6, posterior pillar of the fornix ; Y, hippocampus major ; 8, cminentia collateralis ; 9, lateral portions of the fornix; 10, choroid plexus; 11, taenia semicircularis ; 12. corpus striatum. From the statement in previous lectures of the experimen- tal and clinical deductions as to the various portions of the cortex, we may be able now to use with profit the two axioms which Foster, ' in his work upon physiology, lays down as to the general plan of action of the brain in all its different parts. Thus, he says; ''The preceding discussions enable us to lay down two broad propositions : ^ Mich. Foster, "A Text-Book of Physiology." London, 1878. 56 THE BRAIN. "1. The functions of tlie cerebral convolutions are emi- nently psycliicalm nature ; these parts intervene onl^^in those operations of the nervous system in which an intelligent con- sciousness and volition play a part. "2. The hinder parts of the brain, viz., the corpora quad- rigemina, crura cerebri, pons Varolii, cerebellum, and medulla oblongata, are capable by themselves of carrying into execu- tion complex movements^ the coordination of which implies very considerable elaboration of afferent impulses ; and they can, in the case of animals, even do this with the total ab- sence of the cerebral hemispheres, corpora striata, and optic thalami." The hypothesis, which was long since advanced by Car- penter* and also by Todd," that the corpus striatum is called into action in the downward transmission of motor impulses to the opposite side of the body, and that the optic thalamus was the center of elaboration and transmission upward of sensory impressions^ seems to be accepted as proven by some authors, while others are inclined to regard it, in the light of imperfect evidence, as a pleasing but specu- lative theory. The distribution of the fibers of the crus cerebri certainly points strongly to the corpus striatum as a motor ganglion, and to the optic thalamus as one destined to preside over sensory impulses. The results of experimental investigation as to the corpora striata ' can hardly be said to warrant any positive deductions. In some instances, the entire removal of these ganglia resulted in no loss of either sensation or motion, although it is a well- recognized clinical fact that haemorrhage into this ganglion causes hemiplegia of the opposite side.* It would seem also that convulsions are more frequently produced by lesions con- fined to the corpora striata than when affecting the oi^tic tha- ' W. B. CarpenttM-, " Principles of Human Physiology." ' Todd and Bowman, " Physiological Anatomy." 3 The corpus striatum of each hemisphere tiUicn collectively ; hence the plural termi- nation. * Probably the pressure created upon the anterior part of the internal capsule cxplaina these phenomena. (See Fig. 8.) TEE BASAL GANGLIA, 57 lami, and these convulsive movements are generally crossed, like the paralysis of motion, in case of haemorrhage. Both Fer- rier ' and Burdon- Sanderson ' found that galvanic stimulation of the corpus striatum could be made to produce convulsive movements, and occasionally a condition of complete pleuros- thotonos of the opposite side. The two portions of the corpus striatum which are now recognized, viz., the ventricular portion' and the lenticular nucleus, have both been the subject of special investigation by Nothnagel ; * but, while neither seemed to be concerned in the perception of sensory impressions, nothing of a positive character as regards the functions of the two portions was proven, although the ventricular portion seemed to show less effect upon voluntary motion than the lenticular nucleus, when both sides were destroyed. The optic thalami were once supposed to be the chief gan- glia of vision, but that this is an error investigation seems to have partly proven. Longet' has succeeded in destroying them upon the two sides, and has been unable to note any impairment in vision or influence upon the movements of the pupil ; but Lusanna and Lemoigne ' state that blindness of the opposite eye followed destruction of the ganglion upon one side only. Cases of cerebral haemorrhage throw but little light upon the function of these ganglia, since the destruction of brain tissue is seldom, if ever, confined to these ganglia only, and, in those cases where its limits were nearly confined to this region, paralysis of sensation of the opposite half of the body has been noticed without actual loss of motion upon that side, although the movements may have been somewhat en- feebled.' ^ "Functions of the Brain," New York, 1879. 2 "Proc. Roy. Soc.," 1875. ^ Another name for the " caudate nucleus " of the corpus striatum. * Virchow's " Arehiv," 1873. This observer used injections of chromic acid into the lenticular nucleus, and destroyed the caudate nucleus by means of a special instrument. * " Traite de Physiologic." « "Fistologia die Centri Nervosi Encefalici," 1871. ' Brown-Sequard, "Arehiv. de Physiol," 1877. 58 I^E BRAIN. THE CORPORA QUADRIGEMINA. The experiments of Adamiik, ' by whicli he endeavored to prove the existence of a center or a collection of centers in the nates, whose function was to control the movements of the eyeball, will be considered in connection with the motor ocnli nerve.' They seem to be substantiated in great measure by Hensen, Yoelkers, and Knoll ; and that a center also exists in the nates which contracts the pupil is quite as positively ascertained. This arrangement is in accordance with the wise provisions of nature, since the movements of the eyeball and the pupil (which are constantly associated) are thus controlled by centers in close proximity to each other. The experiments of Hensen,' and also of Voelkers,* seem to point to the aqueduct of Sylvius, which lies immedi- ately underneath the tubercula quadrigemina, as the exact seat of these centers, since stimulation of the deep por- tions of the nates after section produces more uniform re- sults than could be obtained before the deeper parts were exposed. Destruction of either side, in the region of these ganglia, produces blindness of the opposite eye ; but the animal can see, even after the cerebral hemispheres have been removed, in case the tubercula quadrigemina are left intact. This latter statement seems somewhat at variance with the results of experiments of Ferrier upon the angular gyrus, as given in a previous lecture of this course, in which vision was utterly lost when both sides were destroyed ; but it only goes to show that the cerebral hemispheres are in some way connected with the tubercula quadrigemina in the perceptions gained by sight, since, when the helnispheres are removed, an apparently crude vision remains. The sense of sight has a marked effect upon the coordina- ^ " Cbl. mcd. Wisa.," 1870. ^ Sec later pages of this volume. 3 «' Archiv. f. Ophthalmol.," 1878. * Ihid., 1878. p THE CENTER FOR OCULAR MOVEMENTS. 59 tion of movement/ and the discovery of Flourens/ that the removal of the tubercula quadrigemina created impairment of this power, sustains the belief that the ganglion of vision must be in some way associated either with the cerebellum, crura, or pons Varolii, in their effects upon coordination of muscular movements. I THE CRURA CEREBRI AND PONS VAROLII. These parts form the larger portion of the meso-cephalon, and are abundantly supplied with gray matter, which seems to be mixed throughout its interior. We thus infer that these parts have some individual functions, in addition to being simply connecting commissures between the upper parts of the brain and spinal cord, but what these functions are it is difficult, at present, to say. Both of these regions are unques- tionably connected in some way with the power of coordina- tion of muscular movement, since section of either of them ! Insults in marked disorder of this function, and often in un- ■atural and forced movements. I The fact that some of the nerve fibers decussate in these fcgions seems proven by clinical evidence, since lesions of the pons Varolii often ^Todiuo^e. paralysis of the facial nerve upon the same side as the lesion, while the opposite side of the body ■ affected below the face.' I The facial nerve makes its exit from the side of the me- RuUa oblongata ; some of its roots of origin can be traced as far as the floor of the fourth ventricle, others come from the lower part of the medulla oblongata, and others descend from the ^ This subject is quite fully discussed in connection with the optic nerve. ' " Recherches experimentales sur les proprietes ct les fonctions du syst^me nerveux," 15. ^ This class of paralysis, where certain cranial nerves are paralyzed on the same side the existing lesion, while the body is rendered hemiplegic on the opposite side, is Q2X\q^ '■'' crossed paralysis'''' (the " paralysie alterne " of the French). It presents sfwr«^ types depending upon the cranial nerve affected ; hence the so-called third nerve (motor oculi) and body type, the fifth nerve (trigeminus) and body type, the seventh nerve (facial) and body type. Professor Romberg of Berlin and Gubler of Paris have done much to elucidate the clear appreciation of this complex form of paralysis and the mechanism of its production. 60 THE BRAIK upper border of the pons Varolii, where they probably decus- sate. Now, a lesion existing in a lateral half of the pons Va- rolii will, therefore, produce a paralysis of the corresponding facial nerve and of the opposite spinal nerves ; whereas, if it occur above the point of decussation of the encephalic libers, the paralysis will be on the opposite side for all parts of the body. These facts are shown in the accompanying diagram (Fig. 19). It is obvious, from a study of this diagram, that a lesion of one lateral half of the pons (at l) will cause paralysis of motion and of sensibility of the opposite side of the body generally, and of the corre- sponding side of the face; and that a lesion of the hemi- sphere (at m) will produce pa- ralysis of the opposite side of the face and body. As we might naturally ex- pect from the direction of the fibers of the pons Varolii, this portion of the brain acts as a direct conductor of both motor and sensory impressions from and to the cerebrum ; while the collections of gray matter within its substance prove it to possess some func- tions of its own which are independent of the stimula- tion of the cerebral cortex. Without entering into the different experiments which have been made to determine the exact part which this portion Fig. 19. — A diagram to illustrate the method of production of crossed paralysis. (After Hammond).' rt, the left hemisphere ; 6, right half of pons ; c, right half of medulla oblongata ; f/, right half of spinal cord ; c, right facial nerve ; /, fiber of origin from nucleus in medulla oblongata; Op. rit. ' Op. cit. 3 Qp cit. * " Clinique M6dicale " Discussed and quoted in full in the " Text-Book of Physiology," by A. Flint, Jr. » A. Flint, Jr., " Text-Book of Physiology." New York, 1880. ** See lecture on the auditory nerve. ' Op. cit. THE CEEEBELLUM. 53 Numerous attempts have been made to connect the cere- bellum with the sexual functions, but the results of later ex- periments seem to locate the center of the sexual appetite in the spinal cord, somewhere in the lumbar region. Stimulation of the cerebellum has been observed to create kristaltic movements in the oesophagus and stomach, as own by Budge, ' and diabetes has been observed to follow Ivanism of this ganglion, by Eckhard.^ Some relation be- tween the cerebellum and the intestinal tract seems to be fur- ther demonstrated by the researches of Schiff, who observed that after injuries to the peduncles of the cerebellum an in- flammatory condition of the intestine followed, which was of i so acute a type as to be accompanied with hsemorrhage. ■ The hypothesis of Mitchell, that the cerebellum is the store- r house for nervous force for use in emergencies, is plausible, om the remarkably numerous and intimate connections of is ganglion with other parts of the nervous system, but can t, as yet, be considered as proven. The cerebellum is remarkable for the numerous connections hich exist between it and the other parts of the nervous sys- m. Each hemisphere is connected with the caudate nucleus d the hemisphere of the cerebrum of the opposite side ; so, by special fibers, with the substance of the pons Varolii ,nd the deeper parts of the meso-cephalon (including its gray and white substance) ; again, with the medulla oblongata and the spinal cord ; and, finally, the existence of commissural ■bbers connecting the hemispheres of the cerebellum is prob- F able. The close relation which it bears (1), to the medulla, L^hose numerous centers are doubtless well known to you all ; l|^), to the corpora quadrigemina and its center governing the I vaso-motor function, and having a possible effect upon con- * vulsive movements ; (3), to the '' tegmentum cruris," the great I sensory tract ; and (4), possibly to the third, fourth, and eighth nerves,' which have been traced by some observers to this 1 As quoted by Foster, 2 Eckhard's " Beitrage," 1878. 3 This source of origin is as yet undecided. 64 THE BRAIN. ganglion, certainly seem to point to some most important functions as located in this part of the brain, but at present little can be positively stated. The intimate relation which this ganglion bears to these parts renders it a matter of extreme difficulty to discrim- inate, clinically, between the results of disease of the cerebel- lum and the effects of pressure created upon adjacent regions. When we consider how near the ganglia of vision, the points of origin of the third, fourth, and sixth nerves, and the various nuclei of the fourth ventricle, are to the cerebellum, we can un- derstand why careful observers are loath to accept symptoms referable to the eye or ear as positive evidence of cerebellar disease, and why vomiting, so often present, may not be at- tributed with equal force to pressure exerted upon the me- dulla oblongata. In point of fact, we can only consider the symptom called *' cerebellar ataxia" and the presence of pain in the occipital region as of positive value in the diag- nosis of disease of this ganglion, and even these may often be absent. When the loss or coordination of movement dependent upon disease of the cerebellum is well marked, a x)eculiarity of attitude in walking, called by some authors '' titubation," is developed. The patient walks with the feet widely sepa- rated; the trunk is usually bent forward and sways constantly; while the hands and arms are used to preserve the equilibrium of the body. The absence of all spasmodic movement, of tre- mor, and of the want of harmony between antagonistic groups of muscles, as seen in true ataxia, tends to distinguish it from other forms of disease. The upper extremities are usually free from this imperfect coordination ; closing of the eyes sometimes increases the ataxic symptoms, but often fails to affect them ; the recumbent position seems to arrest all symp- toms of incoordination ; and the general condition closely re- sembles that of alcoholic intoxication. The recent researches of Nothnagel, in which he publishes the analysis of over two hundred and fifty cases, seem to point to the superior vermi- form process as the region most liable to produce this type of THE MEDULLA OBLONGATA. 65 ataxia. He states that, if the patient be barefoot, the toes will be seen to be in active motion ; that the patient will bring the foot to the floor, sometimes on the heel and sometimes on the ball, irrespective of intention, thus giv- ing an irregularity to the move- ments of that member ; that the body will sway to and fro ; and that the legs will be separated in order to afford additional security in the standing or w^alking position. THE MEDULLA OBLON-GATA. This ganglion — the upiDermost portion of the spinal cord — is the true nerve center^ of animal life^ since immediate death follows se- vere injury to its substance. The fact that the seventh, eighth, ninth, tenth, eleventh, and twelfth nerves arise directly from this ganglion, and that some fibers from other of the remaining six cranial nerves can be traced to the cavity of the medulla — the fourth ventricle — serves to explain the importance of this special nerve center. In addition to the special influence of the medulla oblongata upon the nerves which arise from it, it con- tains most of the fibers which are distributed to the other parts of the encephalon, and thus it must transmit both the motor and sen- sory impulses, as they pass from and enter the cerebrum. VtltWVt «\;t.iK\.Vt. Fig. 21. — Anterior vieio of the me- dulla oblongata. (Sappey.) 1, infundibulum ; 2, tuber cinereum ; 3, corpora albicantia; 4, cere- bral peduncle ; 6, tuber annu- lare ; 6, ori-iin of the middle pe- duncle of tlie cerebellum ; 7, anterior pyramids of the medul- la oblongata ; 8, decuasation of the anterior pyramids ; 9, oliva- ry bodies ; 10, restiform bodies ; 11, arciform fiber's ; 12, upper extremity of the spinal cord ; 13, ligamentum denticulatum ; 14, 14, dura mater of the cord ; 15, optic tracts ; 16, chiasm of the optic nerves ; 17, motor ocu- li communis ; 18, patheticus ; 19, fifth nerve ; 20, motor oculi externus ; 21, facial nerve; 22, auditory nerve ; 23, nerve of Wrisbei'g ; 24, glosso-pharynge- al nerve ; 25, pneumogastric ; 26, 26, spinal accessory ; 27, sublingual nerve; 28, 29, 30, cervical nerves. 66 THE BRAm. The medulla is possessed of a large amount of gray mat- ter within its interior, where it fonns the lining of the cavity of the fourth ventricle ; and it is in this gray matter that the action of the medulla, which is largely reflex in character, takes place. From the nerves which spring from its sub- stance, we should expect that these reflex acts should be chiefly concerned in the movements of the facial muscles by means of the seventh nerve ; with audition by means of the eighth ; with deglutition by means of the ninth ; with res- piration through the pneumogastric or tenth nerve ; with phonation and the action of the heart by means of the spi- nal accessory ; and with lingual movements by means of the hypo-glossal. Various collections of gray matter in the floor of the fourth ventricle have been described by Lockhart Clarke, who has connected them with special nerve roots ; while experimental investigation has also determined certain special pltysiologi- cal centers to have their seat within the substance of the medulla oblongata. As the former centers may be found in almost all of the later works upon descriptive anatomy,' an enumeration only of the physiological centers will be given, since their presence adds much to the interest which per- tains to the medulla as a reflex ganglion. 1. The respiratory center^ which governs the respu-atory acts, in response to sensory impressions transmitted to it by means of the pneumogastric nerve. 2. The vaso-motor center ^^ which seems to control the * The f mirth a'anial nerve is said to arise from a nucleus on the outer side of the lo- cus coeruleus. The trigeminus (fifth cranial) nerve probably arises from two nuclei situa- ted at the outer angle of the floor of the fourth ventricle ; the more external or sensory nucleus being continuous with the gray tubercle of Rolando, while the internal or motor nucleus lies close to the sensory nucleus, but nearer the median line. In the upper half of the fourth ventricle, the sixth cranial nerve and seventh cranial nerve (facial) take their origin from distinct nuclei. The auditor y na-vc (eighth cranial) has two separate nuclei, as has the fifth cranial, called the internal and external auditory nuclei, which arc situated below those of the trigeminus nerve and above the nucleus for the glosso-pharyngeal nerve. Finally, in the lower half of the fourth ventricle, close to the postero-mcdian fis- sure, are found separate nuclei of origin for the glosso-pharyngeal, pneumogastric, the accessory portion of the spinal accessory, and the hypo-glossal nerves. ' The upper limit of this center in the rabbit is placed by Owsjannikow (Ludwig's CENTERS OF TEE MEDULLA. 67 caliber of the larger blood-vessels, by means of efferent im- pulses, transmitted chiefly through the splanchnic nerves, which affect the muscular coat of the vessels of the thorax, abdomen, and pelvis. 3. The cardio-inhihitory center^ by which the heart is arrested in diastole, or held Under control,' in response to sensory impressions carried to the medulla from other sources Wm means of sensory nerves. !■ 4. The center for deglutition, w^hich controls both the ^!Scond and third stages of that act, or from the time when the '. bolus passes the isthmus of the fauces." 5. The center for the movements of the oesophagus and the stomachy with its allied center for the control of the mechanism of the act of vomiting. 6. The diabetic center ^^ which, when stimulated, produces a saccharine condition of the urine. 7. The salivary center,'' which, upon excitation, tends to increase the flow of the saliva, and possibly, also, the pancre- atic fluid and the other digestive juices. " Avbeitem," ISVl) at about 2 mm. below the tubercula quadrigemina, and its lower limit at about 4 or 5 mm. above the calamus scriptorius. Clarke locates it near to the I origin of the facial nerve, and claims that large multipolar cells can be detected in the vaso-motor area ; while Dittmar (Ludwig's " Arbeitem," 1873) places it chiefly in the lat- , eral columns, after the fibers have been given off to the decussating pyramids. Besides ! this vaso-motor center in the medulla oblongata, other parts of the spinal cord unques- tionably exert a positive vaso-motor influence, causing constriction or dilatation of the blood-vessels. ^ If the mesentery of a frog be exposed, and a slight tap be given it by the handle of the scalpel, the heart will at once cease to beat, but will soon resume its function. This experim.ent, coupled with many others of interest, seems to point definitely to the medulla as the seat of mediation between affei'ent sensory impulses and efferent inhibitory im- pulses upon the heart. ^^ '-^ This subject will be found discussed, at some length, in the pages devoted to the iBchanism of deglutition, as well as the movements of the oesophagus. IB 8 The diabetic center, as marked out by Eckhard, corresponds closely to that defined HB Owsjannikow as the vaso-motor area. Pricking of this center in a well-fed rabbit will "produce a considerable amouut of sugar in the urine, within an hour or two following the ; experiment. This effect is poorly marked in animals whose livers have been deprived of : glycogen by starvation. I * The flow of saliva is apparently a reflex act dependent upon afferent impulses per- I ccived through the gustatoiy branch of the fifth cranial nerve, the efferent impulse being transmitted by means of the chorda tympani branch of the facial nerve. It is this func- tion of the latter nerve that is considered by some physiologists as explanatory of the effect of the chorda upon taste. (See pages descriptive of the facial nerve and its branches.) 68 THE BEAIK Finally, it is proven tliat tlie medulla oblongata in animals plays a part in the coordination of movement, and it may be considered probable that in man the same property is like- wise possessed ; but it is, unfortunately, incapable of demon- stration, as the death of the individual usually follows any traumatic lesion of this ganglion. The clinical aspects of the medulla, its minute anatomy, and its physiological construction, will be more fully consid- ered in connection with the spinal cord and cranial nerves. THE SURGICAL BEARINGS OF CEREBRAL TOPOGRAPHY. In the year 1861, Broca invented a scientific method of de- termining the relations of different parts of the cerebrum to the exterior of the skull, which consisted of driving pegs through the skulls of animals and of cadavers, holes having been previously bored through the bone in order to prevent fracture and injury to surrounding parts. The skull-cap was then removed with extreme care, and the convolutions which were wounded were thus determined. It was discovered by this observer that the fissure of Rolando^ whose relation to the coronal suture was then unknown, lay obliquely, and that its upper extremity could be placed, with great accuracy in man, at a point situated/br^^ millimetres heJilnd the coro- nal suture. This fissure was i)articularly studied on account of its relation to the motor region of the cortex^ and its exact bearing to the exterior of the skull was therefore of great im- portance. The same observer was also able to prove that the external par ieto-occipital fissure of the cerebrum lay under the lambdoid suture of the cranium. In 1873, the experiments of Heftier and Bischoff were added to those of Broca, while Tur- ner followed with his researches in 1874, and Fere in 1875. The drawings which Turner furnished were admirable in their way, but are, to my mind, hardly adapted to the purposes of the surgeon, since the guides which the bony prominences of the skull afford are not brought into such prominence as to be readily comprehended by the casual reader. If the sui'geon is SURGICAL GUIDES OF CRANIUM. 69 to utilize the valuable researches of the investigators above named (and several most brilliant surgical operations have already been performed from the light which the newly ac- quired knowledge of the topography of the cerebrum has af- forded), certain bony prominences of the skull must be des- ignated, as of importance, as guides to the special convolu- tions and fissures of the brain. ISTow, there is one line which is easily drawn upon the head of the living subject (the alve- o-condyloid plane of Broca), upon which perpendicular lines may be described, intersecting certain bony points, which lines can be utilized as guides to parts whose situation is now positively known. This base line should be a straight one, and should intersect the tip of the mastoid process and the line of the cusps of the teeth of the upper jaw. ^ This is the natural posture of the human skull, when the pper jaw is removed and the skull placed upon a table ; nee it is a plane admirably adapted for the study of the ides (which will be given), upon the skeleton, in the ofiice each practitioner, previous to an operation. Furthermore, skull can easily be painted upon its exterior so as to bring e lines, designated as important, into prominence, and so sist the surgeon in the review of those points which pos- sess special value. The contribution of Fere is, to my mind, e best of all the authors named, since it presents the points ^ost needed by the surgeon in a practical way ; and the resume of his guides is so tersely and clearly stated by my friend Professor Seguin that it would be useless to attempt to improve upon it. It will be perceived in the plate, intro- duced to make these guides more clear than a mere verbal description, that the line described, viz., the alveolo-condy- loid plane of Broca, is used as a base line upon which to erect perpendiculars at distances which can be accurately measured upon it ; and that these perpendicular lines inter- ^ This author places the line as intersecting the condyle of the occipital bone ; but, as this can not be felt in the living subject, and as it corresponds to the tip of the mastoid process, I have modified the guide so as to simplify its exact situation upon the exterior of the skull. 7 r set 70 THE BEAiy, sect certain regions which, from facts previously recorded, are of the greatest importance. I quote the resume of Seguin ' upon this special department of cerebral localization : 4 A Fig. 22. — Outline of skull resting upon the alveolo-condyloid plane of Broca. (Modified from Topinard's " Anthropology " by Seguin.) Vertical line a, or auriculo-bregmatic. Line 9-10, drawn parallel to the plane of Broca. Upon this line, at a distance of 45 mm. posterior to the bregma, a vertical line, 1-2, will pass through the upper (inner) end of the fissure of Rolando, ft, 6, and through the posterior extremity of the thalamus opticus (c). A third vertical line, 3-4, drawn at 30 mm, forward of the bregma, will pass through the fold of the third frontal gyrus (a), and through the head of the nucleus caudatus {d). The horizontal line, 7-8, at 45 mm. below the bregma (scalp), indicates the upper limit of the central ganglia. The third horizontal line, 5-6, passing through the external angular pro- cess of the frontal bone and the occi pi to-parietal junction, approximately indicates the course of the fissure of Sylvius, and serves for measurements. At 18 or 20 mm. behind the external angular process on this line is the speech center of Broca ; 5 to 8 mm. behind the intersection of 3-4 and 5-6 is the beginning of the fissure of Sylvius, and at 28 or 30 mm. behind this intersection is the lower end of the fissure of Ro- lando, 6, 6, placed a little too far back in the cut. At x (near 6), near the median line, is the location of the occipito-parietal fissure. '^1. A vertical line (a) drawn from the alveolo-condyloid plane, through the external auditory meatus upward, will pass through or veiy near to the bregma, or line of junction of the frontal and parietal bones at the vertex ; it passes through the anterior (lower) extremity of the fissure of Rolando. *' 2. If, from the upper end of this vertical line a, we mea- sure a distance of 45 mm." backward toward the occiput and ' "Medical Record," 1878. ' A millimetre is about one twenty-fifth of an inch. I SURGICAL GUIDES OF CRANIUM. Yl draw a descending vertical line (1-2), we mark out the location of two most important parts of the cerebrum, viz., the poste- rior extremity of the fissure of Rolando [at h\ and the poste- rior limit of the thalamus opticus in the hemisphere [at c]. ''3. To conclude with the occipital end of the skull ; if we can make out with the finger the lambdoid suture at the medi- an line, we thus learn the situation of the subjacent occipito-pa- rietal fissure, which separates the parietal and occipital lobes. ' ' 4. The last vertical line worth noting is one drawn at a distance of 30 mm. forward of the auriculo-bregmatic line. This vertical line (3-4) will pass through the middle fold of the third frontal convolution (just forward of the speech cen- ter), and will also indicate the anterior limit of the central cerebral ganglia, viz., the head of the nucleus caudatus in the hemisphere [at d\. '' 5. The upper level of the central cerebral ganglia may be quite exactly indicated by an horizontal line drawn at a dis- tance of 45 mm. below the surface of the scalp, at the bregma, (or 35 below the surface of the bare skull at the same point). This line (7-8) also runs across the middle regions of the mo- tor district of the convolutions, containing centers for the face and upper extremities. ^'6. The external angular process of the frontal bone, not difficult to define in the living subject, is the starting- point of another horizontal line {5-6), whose posterior ex- tremity passes a little below the lambdoid suture. Upon this horizontal line we can, by measurement, determine the loca- tion of certain parts. Thus, at a distance of 18 or 20 mm. be- hind the external angular process, lies the folded part of the third frontal convolution (a). This point, in many heads, will correspond to the vertical line 3-4. "7. The situation of the fissure of Sylvius may be approx- imately ascertained in the following manner : Its middle por- \ tion extends horizontally, almost under the upper part of the squamous suture, which in the living subject is to be found a little below the horizontal line 5-6. The anterior extremity or beginning of the fissure of Sylvius is a little below this hori- 72 THE BRAIK zontal line, at a distance of some 5 to 8 mm. posterior to the intersection of 3-4 and 5-Q^ and consequently about 22 or 25 mm. anterior to the auric ulo-bregmatic line a. Lastly, accord- ing to Turner, the parietal eminence almost always overlies the supra-marginal gyrus (P', Fig. 23), consequently the posterior extremity of the fissure of Sylvius is likewise in this vicinity. ''8. The angular gyrus is to be found below and behind the parietal eminence, a little above the horizontal line drawn from the external angular process {5-Q). " 9. The anterior (lower) end of the fissure of Rolando lies at a distance of 28 or 30 mm. behind the line 3-4, and a little above 5-6. It is, therefore, a few millimetres anterior to tlie vertical line a." With this plate as a guide, and with a thorough knowledge of the facts comprised in previous pages of this chapter, it is not out of the bounds of possibility to definitely locate the existence of lesions in certain portions of the human brain, to map out their situation upon the exterior of the skull, and to reach them with surgical means of relief, provided the case be one which would justify such a measure. When Broca has been successful in trephining directly over an ab- scess of the third frontal convolution, w^hich was suspected, and when successful cases have been reported of trephining of the skull for fragments of the inner plate which were com- pressing the ascending gyri of the frontal and parietal lobes, thus causing paralysis, have we not every reason to hope that the day is coming when the rules governing this operation will be those based upon science rather than upon empiricism, and when the surgeon will owe his success to the researches of the physiologist and the labors of the pathologist ? There are certain suggestions, which may be thrown out in this connection, which are safe ones to follow in cases where the propriety of surgical relief is called into question. These may be stated in the form of propositions, which are of neces- sity based upon the contents of the previous lectures. 1. If the injury sustained, provided the case in question be one of a traumatic origin, be situated over the motor area RULES FOR TREPHINING. 73 of the cortex, tlie presence of ancesthesia in combination with motor hemiplegia is a contraindication to attempts at surgical relief. This symptom (anaesthesia) probably indicates some injury to the posterior third of the internal capsule, or to the white substance of the hemispheres ; hence the lesion is proba- bly too extensive to be relieved by trephining. 2. If the sensory region of the cortex be involved, and ralysis or convulsive movements occur, an operation is con- traindicated ; since the lesion has either been so extensive as to ex:tend to the motor area, or has torn or compressed the cerebrum at a point removed from the apparent seat of injury. 3. The occurrence of paralysis on the same side as that upon which the injury was received is always a contraindica- tion to any surgical procedure at the seat of injury, since it usually indicates some lesion of the opposite side, probably (ependent upon transmitted force {contre-coup). 4. The completeness of the paralysis maybe often taken I a guide to the amount of injury done to the cerebrum : if tne paralysis be very profound, the chance of success from trephining is extremely small, since the injury has probably affected parts deeper than the cortex centers. 5. The appearance of paralysis of any of the special nerves of the cranium^ or the development of the symptoms due to 1 lesions of the base of the brain or of the basal ganglia, such as : the Cheyne-Stokes respiration,' choked disk, and vomiting, may be regarded as contraindications to surgical interference. 6. When an injury to the skull is followed, after a lapse jj of some weeks, by aphasia^ the diagnosis of abscess of the I base of the third frontal convolution, or possibly involving li the island of Reil or the white substance situated between the third frontal convolution and the basis of the cerebrum, may be safely made. ' In such a case, the operation of trephining, ^^ performed by Broca, affords a strong probability of relief. HI 7. Cases of injury which are followed immediately hy ^^phasia are strongly diagnostic of either a spicula of bone or He ^ A respiration whose rhytlim steadily increases, and then decreases, in a short inter- P&l of time ; described in 1818 by Cheyne, and by Stokes in 1846. H ^ Authorities are not all in accord with this statement. 74 THE BRAIN. the pressure of a clot in the neighborhood of the center of Broca. The f oraier condition would be strongly in support of surgical interference, since it would probably continue to cre- ate pressure or irritation until removed, while the pressure of a clot might also be relieved by trephining. 8. If the region over the fissure of Rolando be subjected to apparent injury, and the symptoms of some of the special types of monoplegia appear (affecting the muscles of the face, arm, leg, or any of these combined '), or even the occurrence of a slight form of hemiplegia follow, successful trephining may be reasonably expected. The presence of anaesthesia, as before mentioned, would, however, still be a strong contra- indication to such a step, since it would prove that the lesion was probably of too deep a character to be benefited by the simple removal of a button of bone, as the posterior third of the internal capsule would probably be found to be impah'ed. It must be also remembered that the motor paralysis, of what- ever kind it may be, must be confined to the side of the body opposite to the seat of injury, if benefit is to be expected. The type of monoplegia which exists may often be used as a guide to determine the extent of the lesion as well as its situation.' GENERAL SUMMARY OF THE BRAIN-, AND ITS CLINICAL RELA- TIONS. We have now considered the various parts of the brain somewhat in detail, and have noted some of the points of clinical interest which each presents. Many anatomical tenns have, however, been employed at various times, which may be a source of embarrassment to you, provided you are not perfectly familiar with the anatomical construction of the encephalon. I have deemed it advisable, therefore, to hastily review such anatomical points as seem important for you to grasp (as a preparation for clinical study), before I bring this ' See page 45 of this volume. ' Sec the motor centers situated in the asccndinp; frontal and parietal convolutions, page 39 of this volume, and the various forms of monoplcj^ia described in the early pages of this chapter. GENERAL SUMMARY. 75 subject to a close, and pass to tlie other portions of the ner- vous system. The gray matter of the exterior surface (the cortex) of the cerebrum and cerebeUum forms a true ganglionic mass, which is spread out over a large expanse of surface, but which, like all ganglionic masses, consists of nerve cells, nerve fibers, blood-vessels, and the connective tissue of the brain — the neu- roglia. The rapid growth of the requirements which advanc- ing age demands of this gray matter of the cortex demands a larger expanse of surface than the Interior of the skull would admit of, provided this gray matter was smoothly distrib- uted ; hence the presence of convolutions, or "gyri," and the depressions between them, the ''sulci," which are much more marked in the adult than in the infant. It should be understood also that the gray matter of the cortex is of nearly the same thickness in all portions, and that it there- fore lines the sulci, as well as covers the convolutions. The foldings of the gray cortical layer are, however, not of a uniform character; hence a difference in the depth of the depressions between them. It lias been found necessary to name some of the more prominent fissures or ''sulci," in or- der to have certain easily defined landmarks, for the purpose of more readily designating the separate convolutions, which are apparently arranged as a confused mass, but which are found to be uniformly developed and constant in their situation. The admirable monograph of Ecker on the topography of the cerebral convolutions and the researches of Ferrier ' and Dalton'' enable us so to group these various gyri and fissures as to assist us in retaining them in our memories ; while such a knowledge is indispensable to a complete understanding either of the images w^hich have preceded or of those which are to follow. We may start, then, with the statement that we have to know the situation of four lobes, four lobules, and four prin- cipal fissures or " sulci." These may be given as follows : ' Op. cit. 2 " Text-Book of Physiology." H. C. Lea, Philadelphia, 1876. 76 THE BEAIK The fofr sulci are The foue lobes are: C Ascending limb of the fissure of Sylvius. J Horizon till limb of the fissure of Sylvius. J The fissure of Rolando. [ The external parieto-occipital fissure. The frontal lobe. The parietal lobe. The temporo-sphenoidal lobe. The occipital lobe. (The lobulus centralis (the island of Reil). The lobulus para-centralis. Ihe lobulus cuneus. The lobulus quadratus. Fig. 23. — Lateral view of the human brain, showing its lobes and fissures. (After Ferrier.) F, frontal lobe ; P, parietal lobe ; 0, occipital lobe ; T, temporo-spbenoidal lobe ; S, fis- sure of Sylvius ; S', horizontal portion ; S", ascending portion of the same ; c, sulcus centralis or fissure of Rolando ; A, anterior central convolution or ascending frontal ; B, posterior central convolution or ascending parietal ; Fj, superior; Fj, middle; Fs, inferior frontal convolution ; fi, superior; fj, inferior frontal sulcus; f 3, sulcus pr«?- centralis ; Pi, superior parietal lobule, or postero-parietal lobule ; Pa, inferior parietal lobule, viz. : Pa, gyrus supra-marginalis ; P3', gyrus angularis ; p, sulcus intra-pa- rietalis ; c, ni, termination of the calloso-marginal fissure ; d first, O2 second, Os third occipital convolutions ; po, parieto-occipital fissure ; o, sulcus occipitalis trans- versus ; Oa, sulcus occipitalis longitudinalis inferior ; Ti first, Ta second, T3 third temporo-sphenoidal convolutions ; ti first, ta second temporo-sphenoidal fissures. GENERAL SUMMARY. ^7 Let US now consider, in a superficial way, the points of value which pertain to each of these special localities, noting such guides as may suggest themselves to aid memory, and following Fig. 23 as we progress, in order to make the descrip- tion more clear than w^ords alone could do. I THE PRINCIPAL FJSSUPvES OF THE CEREBRUM. The ascending limb of the fissure of Sylvius {s^') passes in ^iront of the island of Reil and among the frontal convolutions. H* The horizontal limb of the fissure of Sylvius {s') passes backward behind the island of Reil, and separates the tem- poro-sphenoidal lobe from the frontal and parietal lobes, which lie adjoining it. The fissure of Sylvius has a surgical and medical impor- tance from the fact that it contains the middle cerebral artery, I which is particularly liable to obstruction from the impaction t of an embolus, especially upon the left side of the body ; which I accident is liable to be followed by aphasia, since the center I of speech is supplied by this artery. The fissure of Rolando (c) separates the frontal from the parietal lobe ; it passes downward and forward from the up- per part of the cerebrum till it almost joins the horizontal limb of the Sylvian fissure. It is an important surgical region (see page 40). The external parieto-occipital fissure (po) separates the parietal and occipital lobes, hence its name. It is continued upon the inner surface of the cerebrum as the ''internal pari- eto-occipital fissure." It is very variable in its extent, and is sometimes scarcely recognizable. THE LOBES OF THE CEREBRUM. The FROTCTAL LOBE (F) is contained in the anterior fossa of the skull. It presents four convolutions, ' or ^ See Figs. 12 and 23. 2 The frequent occurrence of an accessory, or fourth fronted convolution in the brains of criminals is noted by Benedikt (" Centralbl. f. d. med. Wiss.," Nov., 1880). It was 78 TEE BRAIN. "gyri," wMcli are specially named. These may be thus stated : The ascending frontal convolution.^ or gyrus (A), which lies anterior to the fissure of Kolando, being separated from the ascending parietal convolution by that fissure. The superior frontal convolution, or gyrus (F,), which joins the ascending gyrus, passing transversely across the fron- tal lobe. The middle frontal convolution.^ or gyrus (Fg), passing paral- lel to the superior. The inferior frontal convolution., or gyrus (F3), lying below the middle, but still running transversely across the fron- tal lobe. The PARIETAL LOBE ' (P) has also four convolutions, or gyri, called the ascending, the supra-marginal, the parietal lobule, and the angular gyrus. The ascending parietal convolution (B) lies back of the fissure of Kolando, being separated from the ascending frontal convolution by means of that fissure. The supra-marginal convolution (P,), th^ parietal lobule (P,), and the angular gyrus (P/), being the other three con- volutions of the parietal lobe, are situated behind the ascending parietal convolution. The TEMPORO-SPHENOiDAL LOBE (T) presents three well- marked convolutions, which run in an antero-posterior direc- tion. They are named as follows : The superior temporo- sphenoidal convolution (T,), which lies below the horizontal limb of the Sylvian fissure, and which is continuous behind with the parietal lobe. found to exist, more or less completely developed, in the majority of brains of this class in his possession. It originated usually by a liifurcation of the middle frontal convolu- tion, occasionally by a bifurcation of the superior frontal convolution. Other points of interest are presented, including the occurrence of a ffth convolution. These facts the author regards as the expression of a great pathological law, that atypical structure is the chief agent in the production of atypical (morbid) performance of function. ^ The letters in parentheses refer to Fig. 2:i, although Fig. 12 will perhaps give a betr tor conception of the convolutions to the reader. GENERAL SUMMARY. 79 The middle temporo-spJienoidal convolution (T,), wMch. be- comes continuous with the angular gyrus, and is con- nected to the middle occipital convolution. The inferior temporo-spJienoidal convolution (Tg), seen on the under surface of the cerebrum, and connected with the third occipital convolution. The OCCIPITAL LOBE (O) presents three badly defined con- volutions, which are superimposed upon each other, and which lie in a more or less antero-posterior direction. The superior occipital convolution (O,) is connected with the parietal lobule. The middle occipital convolution (O,) is connected with the angular gyrus, and also with the middle temporo-sphe- noidal convolution. The inferior occipital convolution (O3) is connected with the inferior temporo-sphenoidal convolution. Fig. 24. — A diagram of the ccrehtim in longitudinal median section. (After Dalton.) 1, calloso-marginal fissure; 2, parieto-occipital fissure ; 3, calearine fissure: A, third ven- tricle ; B, fifth ventricle ; D, anterior crura of fornix ; C, cuneus (occipital lobule) ; Q, praecuneus (lobulus quadratus) ; P, para-central lobe ; C C, corpus callosum ; F, gyrus fornicatus. THE LOBULES OF THE CEREBRUM.^ The lobulus centralis, or the island of Eeil, is deeply sit- uated at the bottom of the fissure of Sylvius, between the 1 See Fiirs. 23 and 24. 80 THE BRAIK frontal and the temporo-sphenoidal lobes. It presents five or six convolutions, which are nearly straight, and which are directed outward and upward. This portion of the cerebrum is probably connected with the faculty of speech. It is sup- plied with blood by the middle cerebral artery. It can not be well shown in a plate, on account of its situation. The para-ccntral lobule (P) is found on the internal sur- face of the cerebrum, in front of the lobulus cuneus. It is of great importance, from a clinical point of view, since we know that disease of this convolution is followed by second- ary degeneration of the motor tract of the brain and spinal cord. The lobulus quadratus (Q) is also situated upon the inner surface of the cerebrum, between the para-central lobule and the lobulus cuneus. The occipital lobule (C) is triangular in form, and lies pos- terior to the lobulus quadratus upon the inner surface of the cerebrum. Certain fissures upon the inner surface of the cerebrum are also perceived, whose names may be met with by you in the descriptions of existing lesions, in special works upon nervous diseases, and which are therefore enumerated. They are named as follows : The calloso-marginal fissure. The internal parieto-occipital fissure. The calcarine fissure. CLINICAL SUBDIVISIONS OF THE BRAIN. In studying the brain from the standpoint of its physiol- ogy and clinical interest, an advantage is gained by a depart- ure from the subdivisions of the encephalon found in most of our standard anatomical treatises; since many points, which could not be omitted in a descriptive treatise without the author incurring censure, are of no importance to the physiologist or pathologist, in our present ignorance as to the w GENERAL SUMMARY. 81 functions of many parts, or the results of disease when con- fined exclusively to them. I am inclined, therefore, to adopt the classification of Professor Seguin, used some years ago in a course of lectures delivered upon this subject,' since it seems to possess perspicuity and many advantages from a clinical standpoint. I quote from the above author as fol- ws : "" 'Tor our purpose I make the following subdivisions of the encephalon — a semi-physiological classification : ' ^'1. The basis cerehri, including all the parts which lie upon the base of the skull, but more especially the pons Va- rolii, crura cerebri, their attached nerves, and the optic and olfactory apparatuses. "2. ThQ great basal ganglia., i. e., the thalamus opticus, nucleus caudatus, nucleus lenticularis, and the corpus quadri- geminum. "3. The white substance of the hemispheres, especially the internal capsule. I" 4. The cortex cerebri. "5. T^Q cerebellum, "The general pathological propositions relative to these Tts are as follows : "1. Lesions of the basis cerebri^ especially if involving e pons Varolii and crura, give rise to the following symp- toms : paralysis (often of crossed variety) ; ansesthesia in the face and limbs ; impairment of equilibrium ; changes within the eyes ; no psychical symptoms. "2. Lesions of the great basal ganglia probably produce , no symptoms unless by encroaching upon the internal capsule i which passes near them. An exception may be the nucleus caudatus. ''3. Lesions of the wTiite center of the heinispheres pro- I duce no symptoms when they do not involve the parts com- ; posing the internal capsule ; if the anterior portion of this ' "N.Y. Med. Record," 1878. 2 lUd., February, 1878. 3 The italics are my own. 82 TEE BRAIN. capsule be injured, we observe paralysis, if i ts posterior part, anaesthesia. ''4. Lesions of the cortex cerebri produce, when located anteriorly, psychical sym^jtoms ; when located in the median regions, paralysis of an imperfect kind, and when situated posteriorly, no symptoms at all (sensory symptoms in animals). ''5. Lesions of the cerebellum produce no symptoms ex- cept by involving adjacent parts containing important motor and sensory tracts, thus giving rise to irregular paralyses, changes in the optic apparatus, symptoms of irritation of the vagus nerve, etc. ^' 6. Lesions in one lateral half of any part of the enceph- alon produce motor and sensory symptoms in the side of the body opposite to the lesion. When the lesion is in one half of the basis cerebri, some symptoms (direct symptoms) are found in the side of the face and head corresponding to the lesion, others in the opposite half of the body (crossed paralysis). "7. Lesions in the median line cause symptoms to appear in both sides of the body. '' 8. Any intra-cranial lesion which acts in such a way as to increase the intra-cranial pressure may produce (in addition to other symptoms) the condition known as choked disk, or neuro-retinitis." SUMMARY OF THE PHYSIOLOGY OF THE CORTEX AND THE EFFECTS OF DISEASE LOCATED IN THAT PORTION OF THE CEREBRUM. From the statements made in previous pages, we may summarize the functions of the cortex (the gray matter of the cerebral convolutions), as well as the symptoms which can be attributed to disease confined to that region, as fol- lows : 1. That, contrary to old statements, the cortex is capable of artificial stimulation ; and that the functions of certain areas can thus be determined with an approach to accuracy. GENERAL SUMMARY. 83 2. That a well-defined relation exists between the cor- tex and certain muscular groups. This has lately been I Fig. 25. — Side view of the brain of man and the areas of the cerebral convolutions. (After Ferrier.) ^ 1 (on the postero-parietal [superior parietal] lobule), advance of the opposite hind-limb as in walking ; 2, 3, 4 (around the upper extremity of the fissure of Rolando), com- plex movements of the opposite leg and arm, and of the trunk, as in swimming ; «, 6, c, d (on the postero-parietal [posterior central] convolution), individual and combined movements of the fingers and wrist of the opposite hand : prehensile move- ments ; 5 (at the posterior extremity of the superior frontal convolution), extension forward of the opposite arm and hand ; 6 (on the upper part of the antero-parietal or ascending frontal [anterior central] convolution), supination and flexion of the opposite forearm ; Y (on the median portion of the same convolution), retraction and elevation of the opposite angle of the mouth by means of the zygomatic muscles ; 8 (lower down on the same convolution), elevation of the ala nasi and upper lip with depression of the lower lip, on the opposite side ; 9, 10 (at the inferior extremity of the same convolution, Broca's convolution), opening of the mouth with 9, protrusion, and 10, retraction of the tongue — region of aphasia, bilateral action; 11 (between 10 and the inferior extremity of the postero-parietal convolution), retraction of the opposite angle of the month, the head turned slightly to one side ; 12 (on the poste- rior portions of the superior and middle frontal convolutions), the eyes open widely, the pupils dilate, and the head and eyes turn toward the opposite side ; 13, 13 (on the supra-marginal lobule and angular gyrus), the eyes move toward the opposite side with an upward 13, or downward 13- deviation ; the pupils generally contracted (cen- ter of vision) ; 14 (of the infra-marginal, or superior [first] temporo-sphenoidal con- volution), pricking of the opposite ear, the head and eyes turn to the opposite side, and the pupils dilate largely (center of hearing). Ferrier, moreover, places the cen- ters of taste and smell at the extremity of the temporo-sphenoidal lobe, and that of touch in the gyrus uncinatus and hippocampus major. 84 THE BRAIX. confirmed on tlie human subject by Dr. Amidon, of this city/ ' " Dr. Amidon's experiments ^ in ca-ebml localization are based on the following propositions: 1. Marked local variations in the temperature of the cephalic contents can be demonstrated by surface thermometers. 2. Cerebral cortical localization is now so far advanced as to warrant the assertion that the psycho-motor centers for one half the body occupy a certain area in the cerebral cortex of the opposite hemisphere. 3. Func tional activity of an organ implies increased blood supply and tissue change, and conse- quent elevation of the tanperature of that organ. 4. Willed contraction of muscles pre- supposes an increased activity of the volitional motor center of those muscles in the cerebral cortex. From this it was natural to make the deduction that voluntary activity in a peripheral part would cause a rise of temperature in the psycho-motor center for that part, which might be indicated by external cerebral thermometers. " Scguin's self-registering surface thermometers were used, numbers of which were applied to the surface to be tested by passing them through holes in rubber straps secured to the head by buckles. The desirable points in the subject experimented on are, a well-shaped head, thin hair, well-developed and trained muscles, power of facial expression, especially of unilateral facial movements and the ability to contract individual muscles, and moderate intelligence. A man is preferable to a woman, and a Eurojjeaii to an African. The mode of performing and recording experiments and the liabilities b error are all fully described, and the following results are given. "The part of the brain underlying the trapezius area is thus seen to be the anterior part of the first frontal convolution. Farther back on the same comes the deltoid, and farther still the biceps area, while that of the triceps probably overlaps to a slight degree the fissure of Rolando. The area for the scaleni, etc., will fall on the second frontal convolution, in front of its middle ; that for the deep extensors of the neck, on the second frontal convolution, near its middle. The pectoralis area will fall on the middle of the second frontal convolution, slightly overlapping the superior frontal sulcus. The area for the latissimus dorsi occupies a similar position farther back. The point of junction of the superior and ascending frontal is occupied by the hand and finger flexors, . while lower on the ascending frontal lies the area for the elevators of the angle of thr mouth, and lower still, that for the orbicularis oris, in front of and above which is tin area for the tongue and the hyoids, which lies on the third frontal convolution. At the base of the ascending parietal convolution, but reaching a slight distance across the fissure of Rolando, lies the platysma area ; higher, the area for the orbicularis palpe- brarum, and higher still, lying partly on the ascending parietal, and partly on the ascend- ing frontal convolutions, is the area for the extensors of the hand and fingers. The ante- rior part of the superior parietal lobule holds the anterior tibial area, behind which lies that of the calf of the leg. On the posterior part of the superior parietal lobule, but falhng chiefly on the first and second occipital gyri, is found the area for the quadriceps extensor femoris, while on the third occipital gyrus and the posterior part of the inferior middle temporal lobule will fall the area for the abdominal muscles. On the posterior parts of the angular gyrus and middle temporal lobule will fall the psoas and iliacus area. The rather indefinite area marked out for the erector spince overlies about equally the pos- terior part of the upper and of the middle temporal lobules, while higher up, over the contiguous portions of the angular and supra-marginal gyri and the superior temporal lobule, is the area for the flexors of the leg on the thigh. On the upper part of the supra-marginal gyrus will fall t!ie area set apart for ocular movements. This transfer- ence of the motor areas from the scalp to the brain leaves but little of the cerebral con- vexity uncovered, viz., the anterior half of the temporo-sphenoidal lobe and the extreme Prize Essay of 1880, "Archives of Medicine," April, 1880. GENERAL SUMMARY. 85 3. That the excitable region of the cortex, where motor effects are chiefly jjroduced, may be stated to be localized in the following parts, if we accept the results obtained by Ter- rier : The ascending frontal convolution ; the base of the first frontal convolution ; the second frontal convolution ; the third frontal convolution ; the ascending parietal convolu- ion ; the first parietal convolution ; and the para-central lob- le. Now, let us see what centers pertain to each of these mvolutions. e center for movements of tlie lips and tongue (the true speech center) lies at the base of the tJiird frontal convo- lution, near the fissure of Sylvius. (See 9, 10, on Fig. 25.) pon the first and second frontal convolutions, you will find a center (see 12, on Fig. 25) : (1) For lateral movements ^of the Tiead ; (2) for elevation of the eyelids ; and (3) for dilatation of the pupil. e ascending frontal convolution presents, from below up- ward, the following centers : For elevation and depres- sion of the corners of the mouth (8 and 7) ; for move- ments of the forearm and the hand (6) ; for extension and the forward movement of the hand and the arm (5) ; centers for complex movements of the arms and legs^ w^hen acting together (2, 3, and 4). The ascending parietal convolution presents, from above downward, four centers for complex movements of the hand and wrist {a, b, c, d ), such as the use of individual fingers, prehensile movements, etc. At its most superior portion, the centers (2, 3, and 4), which control the alter- nating movements of the arm and leg, as in the act of swimming, seem to overlap the ascending parietal convo- lution ; but they are not definitely placed. The superior parietal convolution presents the center which presides over the movements of the leg and foot, as in the act of walking. anterior frontal region. Tliese areas are held to be the outward representation of psycho- motor centers in the cerebral cortex." (Report in "Xew York Med. Jour.," October, 1880.) 86 TEE BRAm. The para-central lobule^ when diseased or excised, seems to exert, through some influences, a gradually extending process of secondary degeneration of the spinal cord. 4. The sensory region of the cortex is confined to the parie- tal, temporal, and occipital lobes of the cerebrum. In it cer- tain centers have been definitely located by Ferrier, which are not, as yet, accepted as fully proven, but which are consid- ered as being rather supported than confuted by clinical and physiological evidence. The angular gyrus is said by this author to present the cen- ters for vision (13, 13), while movements of the eyes also are produced when these regions are stimulated. ' The superior teniporo-spTienoidal convolution is also said to present the centers of hearing (14, 14, 14), while the head and eyes are caused to move toward the opposite side and the pupils to dilate largely. 5. The collection of reported cases of tumors, clots, soft- enings, pressure effects (from exostoses, meningeal exuda- tions, or thickenings, etc.), seems to confirm, to a greater or less extent, the effects of physiological experiment or faradi- zation, and that the following general statements as to the results of lesions of the cortex can be safely used as possess- ing practical value at the bedside. (a) When t\iQ faculty of speech is affected to any extent, or the symptoms of amnesic aphasia exist, it is safe to con- clude that the lesion involves one of three situations, viz. : the anterior convolutions of the island of Reil, the base of the third frontal convolution, or the white substance lying between the third frontal convolution and the base of the cerebrum. ' The lesion, being most frequently met with upon the left side of the brain, will usually be asso- ' Experiments of Ferrier, Yeo, Dalton, and others. » E. C. Seguin, " Med. Record," 1878. GENERAL SUMMARY. 87 ' Fig. 26 — Upper viae of the brain of man ayid the situation of areas of the cerebral con- volutions. (After Ferrier.) (on the postero-parietal [superior parietal] lobule), advance of the opposite hind- limb as in walking ; 2, y, 4 (around the upper extremity of the fissure of Rolando), complex movements of the opposite leg and arm, and of the trunk, as in swim- ming ; «, 6, c, d (on the postero-parietal [posterior central] convolution), indi- vidual and combined movements of the fingers and wrist of the opposite hand ; pre- hensile movements ; 5 (at the posterior extremity of the superior frontal convolu- tion), extension forward of the opposite arm and hand ; 6 (on the upper part of the antero-parietal or ascending frontal [anterior central] convolution), supination and flexion of the opposite forearm ; 7 (on the median portion of the same con- volution), retraction and elevation of the opposite angle of the mouth by means of the zygomatic muscles ; 8 (lower down on the same convolution), elevation of the ala nasi and upper lip with depression of the lower lip, on the opposite side ; 9, 10 (at the inferior extremity of the same convolution, Broca's convolution), open- ing of the mouth with 9, protrusion, and 10, retraction of the tongue — region of aphasia, bilateral action; 11 (between 10 and the inferior extremity of the pos- tero-parietal convolution), retraction of the opposite angle of the mouth, the head turned slightly to one side ; 12 (on the posterior portions of the superior and mid- dle frontal convolutions), the eyes open widely, the pupils dilate, and the head and eyes turn toward the opposite side ; 13, 13 (on the supra-marginal lobule and an- gular gyrus), the eyes move toward the opposite side with an upward 13, or down- ward 13" deviation — the pupils generally contracted (center of vision); 14 (of the infra-marginal, or superior [first] temporo-sphenoidal convolution), pricking of the opposite ear, the head and eyes turn to the opposite side, and the pupils dilate largely (center of hearing), Ferrier, moreover, places the centers of taste and smell at the extremity of the temporo-sphenoidal lobe, and that of touch in the gyrus un- cinatus and hippocampus major. 88 THE BRAm. ciated with some form of paralysis affecting the right side of the body ; but the faculty of speech may be af- fected by lesions of the right side as well as those of the left side. (b) Paralysis of motion affecting the upper extremity^ either entirely or to a greater extent than other parts involved, ' suggests a lesion which is situated on the side opposite to the paralysis ; and either confined to, or involving, the ascending convolutions of the frontal or parietal lobes. (c) When the facial muscles are prominently affected, I am inclined to think the lesion may be located in the frontal lobe, anterior to or in the vicinity of the pre-central fis- sure or sulcus. "" (d) When the muscles of the leg ' are exclusively affected (and the probability of spinal lesions involving only the lateral half of the spinal cord can be excluded), or when the leg muscles, in an attack of hemiplegia of clear cranial ori- gin, show special impairment, the lesion can be probably placed at the upper end of the fissure of Rolando^ affect- ing the ascending convolutions of the frontal or parietal lobes. {e) That lesions of the sensoi^y area of the cerebral cortex are not understood in their clinical aspects^ since little op- portunity has been afforded for the pathological study of this type of cases. (/) That all of the symptoms produced by lesions of the cor- tex may be the result either of actual destruction of the nerve tissue of the cortex, or evidences of irritation of the cortex ; and that the symptoms will differ in the two cases, so as to often assist the diagnostician. {g) That lesions of the cortex, if outside of the motor area^ will produce no symptoms, unless they involve the dura mater ; in which case, the diseased condition may be ^ See the peculiar types of brachial monoplegia, as described on pages 45 and 46 of this volume. ' It may not be confined alone to this region, since the various forms of brachial monoplegia are often associated with facial paralysis. * See the types of crural monoplegia, described on pages 40 and 42 of this yolume. 1 GENERAL SUMMARY. S9 manifested by convulsions^ and, possibly, by headache. These convulsions, and the headache which may be pro- duced, are respective evidences of irritation of some por- tion of the motor area of the cortex, or of adjoining sen- sory areas. (/) That the symptoms which prominently indicate irritation of the cortex are convulsions^ which are oiten followed hy » paralysis. This paralysis may be either of the transient or permanent variety, although the former is the more common. The groups of muscles which are prominently affected in the convulsive attacks may afford the physi- cian a guide to the seat of the irritation, since the same centers are probably affected, as if the corresponding muscles w^ere paralyzed, rather than convulsed. {j) The destructive lesions of the gray matter of the cerebral I convolutions, if limited to the motor area, produce pe- ripheral paralysis of the parts governed by the centers which are involved, but on the side of the body opposite to the situation of the seat of disease. Thus embolism, by plugging the middle cerebral artery, shuts off the blood supply to the center of Broca, and aphasia will usually be produced ; with an accompanying hemiplegia of the side opposite to the embolus, in case the blood supply is impaired to other parts of the motor area. A destructive lesion of the motor region, if not due to em- bolism, is liable to produce hemiplegia, without aphasia, on the opposite side to the seat of disease ; but it exists to a greater or less extent when the motor area of the cortex is affected in any part. {k) When the paralyzed muscles become rigid^ after an at- tack of hemiplegia, from destructive lesions of the motor area of the cortex, it may be considered as an evidence of a secondary degeneration of the nerve fibers, which is progressing downward along the spinal cord. This is prominently developed w^hen the para- central lobule is the seat of disease, but it exists, to a greater or less extent, when the motor area of the cortex is affected in any part. 90 THE BE A IK {T) In those cases where the lesions are diffused over a large surface of the cortex (as in the exudation of acute menin- gitis, suppuration between the bone and the dura mater, etc.), delirium, convulsions, and local pain, are often pres- ent, and may properly be regarded as evidences of the excessive irritation which exists in consequence of the pressure and hypersemia. Coma and paralysis may fol- low ; in which case they are to be attributed, either to the local anaemia produced by the pressure (thus causing im- pairment of nutrition to the subjacent cortex), or to circu- latory changes and increased tension of the entire brain. {m) The affection called ''diffuse meningo-encephalitis " or the ''general paralysis of the insane" is so commonly met with, and affords such striking evidences of the effects of general pressure upon and irritation of the cerebral cortex, that its symptoms have to the neurologist more than a clinical interest. From a careful study of such cases, we learn that the symptoms first manifested are contractions of special fibers in the muscles of the face, tongue, and limbs, and that the speech becomes tremu- lous and the articulation spasmodic. Later on, acute delirium and impairment of memory and judgment ap- pear, and a state of the muscles of the limbs develoj)s which may be one either of semi-paralysis or of semi- ataxia. In the final stages, the mental faculties become abolished ; a state of insanity, characterized by periods of delirium, is produced ; and the patient dies without any apparent changes in the ordinary organic functions of the body. I would repeat, that a person exhibiting tremors of the facial muscles, of the tongue, and hand, a vibratory and slurred speech, angular or tremulous handwriting, and irregular, small pupils, should be suspected of having chronic peri-encephalitis or paralytic dementia. The ad- dition of gradual failure of mind — true dementia — makes the diagnosis certain. In case there should be added to these above named symptoms exalted notions, with ma- p GENERAL SUMMARY. 91 niacal attacks and epileptiform seizures, the case deserves the name of general paresis, and as such the form is more usually seen and studied by asylum physicians. 6. The physiology of the great ganglia of the cerebrum is far from being satisfactorily determined, since the experi- ments of different observers apparently prove most glaring contradictions. It is, however, probable that the two subdi- visions of the corpus striatum (the caudate and the lenticu- r nuclei) have motor functions of a character which are not yet positively decided, while the attributes of the optic thala- mus are still involved in obscurity.' 7. It can safely be considered as proven that the corpora quadrigemina (the nates and testes) are, in some way, con- cerned in the special sense of vision, and belong to the optic apparatus, although the motions of the eyeball seem to be ore directly influenced than vision itself. For the experi- ents which seem to prove this, the reader is referred to ge 58 and 59 of this volume. 8. The internal capsule of the cerebrum seems to be one f the most important regions of the brain, from a clinical standx)oint, since the slightest pressure upon it produces ptoms which vary with the portion pressed upon, and since a secondary degeneration^'' which descends along the nerve fibers of the crus, pons, medulla, and spinal cord, is in- evitably the result of disease of this portion of the cerebrum. If the anterior two thirds of the internal capsule be the seat of pressure or disease, hemiplegia of the opposite side re- sults ; if the posterior third be affected, a condition of ances- thesia of the opposite side is produced. Choreic movements^ which vary in degree and type, and which may appear as athetosis, ataxia, true chorea, or tremor, are strongly diag- nostic of lesion of the internal capsule, provided they follow an attack of hemiplegia or hemi-ansesthesia. * To what extent this ganglion presides over or influences sensory perceptions must be considered unsettled. For opinions on the subject, the reader is referred to page 57 of this volume. 2 For the eifects of this descending t3;pe of secondary degeneration of nerve tissue, see page 44 of this voluinp. i Stan 92 THE BRAIN. 9. The parts adjoining the internal capsule (the caudate nucleus, the lenticular nucleus, the white center of the frontal lobe, and the optic thalamus), if the seat of hsemorrhage, tu- mors, or other lesions which are capable of causing pressure upon it, may produce symptoms similar to those of disease of the internal capsule itself. 10. When the central portions of the cerebral hemispheres are the seat of some type of disease which has been suddenly developed, as in hsemorrhage, acute softening, etc., symptoms referable to the optic apparatus are usually present, in addi- tion to the other symptoms which have been given above. Thus the eyes are often turned away from the paralyzed side, and, therefore, toward the seat of the lesion ; the head also is usually similarly turned ; and, in case the injury done to the brain is severe or extensive, a very marked rise in the surface temperature of the body will be observed. 11. AVhen the pressure upon the central portions of the cerebral hemispheres is gradual^ as in the case of growing tumors, we have developed certain special signs, which de- pend upon the situation of the tumor and the line of its great- est pressure ; but we are also liable to have evidences develoj) in the eye, which are called those of "neuro-retinitis," and may result in the condition known by ophthalmologists as the *' choked disk." THE CRANIAL I^ERYES. lEIR ANATOMY, PHYSIOLOGY, AND CLINICAL VALUE. THE OEANIAL KEEYES. The nerves which arise from the brain are arranged as ' twelve pairs, which from before backward are called the ol- factory, optic, motor oculi, trochlearis, trigemini, abducens, facial, auditory, glosso-pharyngeal, pnenmogastric, spinal ac- cessory, and hypo-glossal. All of these, excepting the ninth, tenth, and eleventh pairs, are confined in their distribution to the head; while the other three have a distribution to the structures of the neck and trunk. THE OLFACTORY XERYE. The first cranial nerve or nerve of smell consists (1) of three roots ; (2) an olfactory process ; (3) a bulb ; and (4) ter- minal branches, which are distributed to the cavities of the nose. The three roots are called the external, middle, and in- ternal. The external root arises apparently from the posterior bor- der of the fissure of Sylvius, and is said to be traceable to the corpus striatum, the anterior commissure, the optic thalamus, and the island of Reil. The internal or short root is said by Foville to be connected with the longitudinal fibers of the gyrus fornicatus. The middle or gray root arises from a pyramidal mass of gray matter, the caruncula mammillaris. 1 Willis has divided the cranial nerves into nine pairs, grouping the seventh and eighth nerves as one pair, and the ninth, tenth, and eleventh as one pair. 96 THE CRANIAL NERVES. All three of the roots join to form a band, which is prismoidal in form (the olfactory process or tract), which passes forward Fig. 27. — Roots of the cranial nerves. (Hirschfeld.) I. First pair; olfactory. II. Second pair ; optic. III. Third pair ; motor oculi communis. IV. Fourth pair; patheticus. V. Fifth pair ; nerve of mastication and trifacial. VI. Sixth pair; motor oculi externus. IX. Glosso-pharyngeal, \ X. Pneumogastric, >• Eighth pair. XI. Spinal accessory, ) XII. Ninth pair; sublingual. The numbers 1 to 15 refer to branches which will be described hereafter. along the floor of the brain in a deep sulcus till it expands into the terminal enlargement, known as the " olfactory bulb," or *^ ganglion." This terminal enlargement lies upon the upp'^r surface of the cribriform plate of the ethmoid bone, through the numerous foramina of which its branches escape, as small, thread-like filaments ; which subsequently form a plexus upon the surface of the Schn^iderian, er pituitary^ membrane of the nose. STRUCTURE OF OLFACTORY FILAMENTS. 97 Fig. 28. — Olfactory ganglion and nerves. (Ilirschfeld.) 1, olfactory ganglion and nerves ; 2, branch of the nasal nerve; 3, sphcno-palatine gan- glion ; 4, 7, branches of the great palatine nerve ; 5, posterior palatine nerve ; 6, mid- dle palatine nerve; 8, 9, branches from the spheno-palatine ganglion; 10,11, 12, Vidian nerve and its branches; 13, external carotid branch from the superior cervical ganglion. The filaments of the olfactory nerve are described by ^lessrs. Todd and Bowman^ as differing in their structure from the ordinary filaments found ill the other cranial nerves, in that they contain no white substance of Schwann, and are nucleated and fine- ly granular in texture. This absence of the white substance, found in other nerves, renders it difficult to trace their course in the Schneiderian membrane ; which difficulty is still further enhanced by the existing nu- clei, which resemble those of the tis- sues through which they pass. The limit of distribution of the olfactory nerves seems to be confined to the superior three fourths of the septum of the nose, the superior tur- l)inated bone, the upper half of the middle turbinated bone, and the roof 1 "Physiological Anatomy Fig. 29. — Terminal filaments of the olfactory nerves ; magnified 30 diameters. (Kolliker.) 1, from the frog— a, epithelial cells of the olfactory region ; 6, olfactory colls. 2. Small branch of the olfactory nerve of the frog, separating at one end into a brush of varicose fibrils. 3. Olfactory cell of the sheep. 98 THE CRANIAL NERVES. of the nasal cavities ; all of which seems to be defined by a brown-colored tesselated epithelium/ Odorous particles, present in the inspired air, as they pass through the lower chambers of the nares, are diffused intr) the upper nasal chambers, and, falling upon the olfactory epithelium," produce sensory impulses which are transmitted to the brain and give rise to the sensations of smell. Forced inspiration, or sniffing, increases the upward dif- fusion of inspired air, and thus a more complete contact of the odorous particles is insured. It seems that, for the development of smell, the odorous particles must be transmitted to the nasal mucous membrane in a gaseous medium, as the simultaneous contact of fluids destroys all appreciation of odor.' Animals with a very acute sense of smell have a modified arrangement of the turbinated bones, to afford a larger ex- panse of surface than exists in man. It has been asserted by some physiologists that the olfac- tory nerve is not the only nerve of smell, and Magendie claimed that animals could perceive the odor of some sub- stances after the olfactory bulbs had been removed. He used ammonia, however, as a test in his experiments, which is hardly a test of smell, as it is a powerful stimulant to the fifth nerve. Bernard' reports cases of absence of the olfactory bulb> in man, where smell existed during life. Prevost,* however. claims that section of the olfactory bulbs entirely destroys the sense of smell. Injury to the JlftJi nerve may also destroy smell, even where the olfactory nerve remains intact ; but this effect is hardly a proof that the nerve is in any way related to that special sense, since the effect is probably due to an altered condition of tlie nasal mucous merribrane^ which prevents its performing its natural function. The loss of smell may, therefore, be of some diagnostic value, if associated with other symptoms referable to impairment of the fifth cranial nerve. » Max Schultze. » Mich. Foster, " Tcxt-Book of Physiology." ■ " Syst. ncrv.," vol. ii. . * " Archives dc sci. phys. et nat.," 1871. i TEE PERCEPTIONS OF ODOR. It seems necessary, in all animals which live in the air, that all odorous materials must enter the nostril to be per- ceived, and, furthermore, that the membrane of the nose must be in a proper condition of moisture ; hence, by breathing through the mouth, the most disagreeable of odors may usu- ally be unperceived, and the blunted sensibility of the power of smell, which occurs in catarrh, may plausibly be explained as the result of a deficient secretion in the early stage of the attack, and of excessive secretion later on in the disease. The curious effects of section or injury of the fifth cranial nerve ujjon the sense of smell may justly be attributed to the alteration in the amount of secretion of the lining membrane of the nose, since this nerve exerts a marked influence upon the secretions of the tissues supplied by it. ymvrr wvviiir Fig. 30. — Internal branches of the olfadori^ nerve. (After Sappcy.) 1, internal branches of the olfactory bulb, ramifying in the mucous membrane covering the septum of the nasal fossae ; 2, internal branch of the ethmoidal division of the nasal nerve; 3, naso-palatine nerves; 4, 5, 6, cavernous plexus; 7, superior or ascending branches of this plexus ; 8, internal carotid branch from the superior cer- vical gandion; 9, 9, filaments connecting this branch with the external carotid branch ; lo, origin of this branch ; 11, ganglion of the glosso-pharyngeal ; 12, jugu- lar ganglion of the pneumogastric ; 13, anastomotic filaments extending from the sympathetic to the two preceding nerves ; 14, anastomosis of the spinal accessory with the pneumogastric; 15, filament connecting the sympathetic with the hypo- glossal ; I, olfactorv ; II, optic ; III, motor oculi ; IV, patheticus -^ V, trigeminus ; VI, abducens; VII,' facial;: yjH.; f?«dv^ory^JX^ ^glp^so-^par^geaf;, X, pneumogas- tric ; XI, spinal accessorij^ i^-^^i Kypo^glos'^al; ? '. ,-,-";;,,' ' act of sn^j^nfi,\^f "^^^^ ^^VforcMo^^^^ of air is through the^hoiiriisVrsVftenane&ft^on"^ of The ■driven throng] INature to get rid of some irritating substance ; and thus, 100 THE CRANIAL NERVES. through the agency of the fifth nerve, is the nose made the portal of the respiratory apparatus, where cognizance of the quality of the air breathed is constantly taken, and where all foreign or injurious matters are at once detected, and often expelled. A marked peculiarity of the olfactory nerve is shown by the fact that no form of irritation of its fibers excites reflex muscular action through other nerves ; * neither is it capable of the sensation of pain, since section of the nerve, or even the destruction of the olfactory ganglia, seems to create no special distress in animals, and the nose retains its normal sensitive- ness until the fifth nerve is also divided. The olfactory nerve, however, may be the source of another variety of marked reflex action. Many cases are recorded where fainting and vomiting have been produced by certain odors ; while, for some unexplained reason, mental associa- tions cluster around sensations of smell more strongly than any other form of impression received from without.'* The importance of the sense of smell among many of the lower animals, in guiding them to their food, or in giving them warning of danger, and also in exciting the sexual feel- ings, is well known. Among the savage tribes, whose senses are more cultivated than those of civilized nations, the scent is almost as acute as in the lower mammalia. It is asserted by Humboldt that the Peruvian Indians, in the middle of the night, can thus distinguish the different races, whether Euro- pean, American, Indian, or Negro. The agreeable or disagreeable character assigned to any particular odor is by no means constant among different indi- viduals. Many of the lower animals pass their whole lives in the midst of odors which are to man (in a civilized condi- tion) in the highest degree revolting, and will even refuse to touch food tii^til pit. is'fsr Udyimced iii;;^trddity.' '- '..►'«.«'', ■■ ,.' ^, •■»• V '''it * ' Carpenter^ " J*rinpiple8 of Physiology." The act^pf vomiting may possibly be con- sidered as an exception \ cases of congestive and inflammatory conditions of the retina ; also where an excessive amount of application of vision has been demanded, in disease and atrophy of the nerve itself, and in slight compression of the nerve from local causes. * This condition is more commonly due to atrophy of the optic nerve and to glaucoma. AMBLYOPIA AND AMAUROSIS. 127 When the optic nerve filaments become ancesthetic, sight is impaired in the exact ratio of the loss of sensibility ; hence we speak of the condition of " amhlyopia^'^'' when the sight is partly destroyed by this condition, and of " amaurosis " when the sight is entirely destroyed. We may consider a loss of sensibility of the optic nerve filaments as a symptom of the gravest import, since it indi- cates either some disease of the brain or some advanced changes of the nerve itself. The hi^ain conditions which are most liable to produce this condition are as follows : neuro- retinitis, which may follow cerebral haemorrhage, cerebral softening, Bright' s disease, lead poisoning, and syphilis; the various forms of ataxia ; cerebral tumors ; chronic effusion into the ventricles ; and hysterical cerebral disorders. The local conditions which may result in optic anaesthesia include inflammation of the retina and the adjoining struc- tures ; haemorrhage into the retina ; retinal tumors ; the com- pression of glaucoma ; pressure of tumors, in the orbit or cranium, upon the optic tracts ; thickening of the meninges in the vicinity of the optic chiasm ; and traumatism. Atrophy and sclerosis of the corpora geniculata may result in amaurosis ;' lesions of the cerebellum "" may be accompanied by symptoms referable to the optic apparatus (probably on account of the pressure created upon adjoining regions of the encephalon) ; and an increase of intra-cranial pressure, from any cause, may produce retinal changes. THE THIRD OR "MOTOR OOULI" NERVE. This nerve has its apparent origin from the inner border of the cms cerebri. The deep origin of the nerve can, however, be traced to the " locus niger,'" and to a gray nucleus in the floor of the aqueduct of Sylvius, slightly below the tubercula quadrigemina. The course of this nerve, after it escapes from the brain, is of importance, from the relations which it has with impor- 1 See p. 58 of this volume. ^ See p. 62 of this volume. 128 THE CRANIAL NERVES. tant structures, and from the physiological phenomena pro- duced by it. It pierces the dura mater opposite to the an- terior clinold process, in order to reach the outer wall of the cavernous sinus, where it lies in close relation with the fourth cranial nerve, and the ophthal- mic branch of the fifth cranial nerve, being above them both, and also with the cavernous sinus, which lies internal to it. It is in this region that the nerve is joined by filaments from the cavernous plexus of the sympathetic system. The nerve now passes from the cavity of the cranium by means of the sphenoidal fis- sure, having, however, divided into two branches, before its escape, called the superior and inferior. In the sphenoidal fissure, these two branches are placed between the two heads of the external rectus muscle of the eyeball, and from this point they pass onward to their re- spective distributions, viz., the superior branch to the levator palpebrse and the superior rectus muscles, and the inferior branch to the inferior oblique, the inferior rectus, and the in- ternal rectus muscles, and, by a small filament, furnishing the motor root to the ciliary or lenticular ganglion of the orbit. The third cranial nerve thus supplies all of the muscles of the eye hut two, viz., the superior oblique and the external rectus muscles, which derive their motor power, respectively. from the fourth and the sixth nerves. It also supplies filaments to the ophthalmic ganglion (which is also called the ciliary, and the lenticular ganglion), which filaments Fig. AZ.— Distribution of the motor oculi communis. (Hirschfcld.) 1, trunk of the motor oculi communis ; 2, superior branch ; 3, filaments which this branch sends to the superior rectus and the levator palpebri superioris ; 4, branch to the internal rectus ; 5, branch to the inferior recttbs ; 6, branch to the inferior oblique muscle ; V, branch to tJie lenticular ganglion ; 8, motor oculi externus ; 9, filaments of the motor oculi externus anastomosing with the sympathetic ; 10, ciliary nerves. THE MOTOR OCULI NERVE. 129 are subsequently distributed to the ciliary muscle and the iris. It is now claimed that the fibers of the third nerve, which pass to the aqueduct of Sylvius, decussate ; and it is to this IG... "^. V Fig. 44. — Ciliary mitscle ; magnijied 10 diameters, (Sappey.) 1, 1, crystalline lens; 2, hyaloid membrane; 3, zone of Zinn; 4, iris; 5, 5, one of the ciliary processes ; 6, 6, radiating fibers of the ciliary muscle ; 7, section of the circu- lar portion of the ciliary muscle ; 8, venous plexus of the ciliary process ; 9, 10, sclerotic coat ; 11, 12, cornea ; 13, epithelial layer of the cornea ; 14, membrane of Descemet; 15, ligamentum iridis pectinatum ; 16, epithelium of the membrane of Descemet; 17, union of the sclerotic coat with the cornea ; 18, section of the canal of Schlemm. anatomical arrangement of its fibers of origin that the effect of the pupil of one eye upon the condition of the pupil of the opposite eye is occasionally observed in disease, and that the muscles of the two eyes, as well as the iris, are thus enabled to work in perfect harmony with each other. As an example of this, it is occasionally observed that, when amaurosis affects one eye, the pupil of the diseased organ will not respond to the effect of light upon the retina of that side, but, when the 130 THE CRANIAL NERVES. light creates a movement of the iris of the unimpaired eye, the pupil of the opposite side also responds, thus showing that reflex action is possible between the two eyes. MECHANISM OF THE CONTRACTION OF THE PUPIL. The mechanism of the reflex act, by which the third nerve is enabled to so affect the contraction and dilatation of the pupil as to have its varying size correspond exactly to the requirements of the retina, as regards the amount of light l ^3 1^ ISlfi 1. 2„ Fig. 45. — Choroid coat of the eye and the ciliary nerves. (Sappey.) 1, optic nerve ; 2, 2, 2, 2, 3, 3, 3, 4, sclerotic coat, divided and turned back to show the choroid ; 5, 5, 6, 5, the cornea, divided into four portions and turned back ; 6, 6, canal of Schlemm ; 7, external surface of the choroid, traversed by the ciliary nerves and one of the long ciliary arteries ; 8, central vessel into which open the vasa vorti- cosa ; 9, 9, 10, 10, choroid zone ; 11,11, ciliary nerves ; 12, long ciliary artery ; 13, 1 3, 13, 13, anterior ciliary arteries ; 14, iris ; 15, 15, vascular circle of the iris ; 16, pupil. necessary for perfect vision at all times and under all circum- stances, is a subject of interest to those who study anatomy from the standpoint of its physiological bearings. The optic nerve, when a person comes from darkness into the light, perceives, on account of the dilated condition of the pupil, an excess of light which at once compels the eye to momen- tarily close* until the pupil shall become contracted. The * A reflex act produced through the optic nerve upon the orbicularis palpebrarum muscle. DISTRIBUTION OF THE THIRD NERVE. 131 sensation of over-stimulation created in the optic nerve by the glare of light entering the dilated pupil is carried back- ward to the brain, and, probably in the region of the aque- duct of Sylvius, creates a reflex act which sends motor im- pulses along the fibers of the third nerve to the iris, by means of the branch to the ciliary ganglion. Thus it happens that, when the eye is again opened, the sensation of distress in the optic nerve is no longer present, and the pupil is found to be contracted in a direct proportion to the amount of light which at the time exists. REASONS FOR THE PECULIAR DISTRIBUTIOK OF THE THIRD XERVE. The distribution of the third cranial nerve may suggest to the inquiring mind the following questions : ''Why does Fig. 46. — Plexus of ciliary nerves. — Nerves of the iris. (After Sappey.) A, choroid ; B, iris ; 1,1,1,1, ciliary nerves dividing at their terminal extremity into two or more branches, which anastomose to form a circular plexus surrounding the greater circumference of the iris ; 2, 2, plexus formed by this anastomosis ; 3, 3, nerves of the iris originating from this plexus. iN'ature use three nerves to control the movements of the six ocular muscles, when she could have used one nerve to accom- plish the effect? Why are the internal rectus, the inferior oblique, and the inferior rectus supplied from one nerve source, to the exclusion of the external rectus, and the supe- 132 THE CRANIAL NERVES. rior oblique muscles ? Furthermore, why is the iris supplied with nerve power from the third nerve, and not also from the fourth nerve or the sixth nerve ? " As was stated in the introductory lecture of this course, when touching upon the distribution of nerves in general, Na- ture often indicates, by the distribution of the nerves, some valuable hints as to the physiology of the parts supplied by each nerve filament ; and such questions, as are presup- posed above, will, if constantly asked by the student of anat- omy, often enable him, by close study, to gain not only information of a most practical kind, but it will also greatly assist him to retain in his memory what would otherwise escape, and render this line of study a source of unceasing pleasure and interest. It is evident, when a glance at the distribution of the mo- tor oculi nerve is taken, that it is essentially the nerve of accommodation of vision for objects of variable distances from the retina. By its control over the internal muscles of the orbit, the eyes can be moved in unison in their endeavor to focus objects simultaneously upon each retina, and thus to gain a perception of the solidity of objects, which can not be afforded by one eye alone. It is a fact, which perhaps the reader has never thought of, that the two external recti mus- cles, or the two superior oblique muscles, are seldom called into simultaneous action, since they both tend to cause the eye to roll outward, and thus oppose the natural move- ment of the two eyes, one of which usually moves inward while the other moves outward, in order to favor the percep- tion of the same objects by the retina of each eye. For this reason alone, it would be impossible that these two muscles of each orbit should be supplied from the same nerve as the other muscles, since they could not possibly act in har- mony with each other. Again, the superior oblique and the external rectus muscles are seldom called into simultaneous action except in oblique movements of the eye, and their actions are so dissimilar that they have often to act both with and without the aid of the other ; hence two nerves (the ACCOMMODATION OF VISION. 133 fourth and sixth) are furnished so that each muscle can have its own source of nerve supply. The distribution of the third nerve to the iris affords a still more beautiful example of the con- stant efforts of Nature to bring all parts into a harmony with each oth- er, and by the simplest means at her control. It has been mentioned, in connection with the optic nerve, that the pupil contracts as the eye is drawn inward, and also in at- tempts to focus near objects upon the retina. Now, the third nerve is the nerve by which not only is the eye drawn inward, but it is also the nerve by which the ciliary muscle of the eye is enabled to affect the cov/oexity of the crystal- line lens of the eye, and thus to act as an adjuster of the focal dis- tance of objects whose images fall upon the retina. How important it is, therefore, that the pupil which is so essential to the proper performance of vision, since it controls the quantity of light admitted to the retina, should be placed under the same nervous control as the muscles of accommodation of vision ! MECHANISM OF THE DILATATION OF THE PUPIL. The pupil is made to dilate by means of muscular fibers, which radiate from the margin of the pupil toward the cir- cumference of the iris. It is probable that these fibers are under the control of the sympathetic system ol nerves.' If so, it must be observed that the sympathetic nerves have an effect upon the iris directly opposite to that which it exercises upon the blood-vessels, since, when it is stimu- ^ Experiments of Julius Budge, 1851, and Augustus Waller, " Gazette Medicale de Paris." Discovered by Petit, 1712. 11 Fig. 47. — Ciliary nerves^ course and termination. (After Sappey.) 1, optic nerve, covered by its exter- nal or ligamentous envelope; 2, optic nerve, covered only by its proper envelope (neurilem- ma); 3, 3, sclerotic, or fibrous envelope of the eyeball : 4, 4, iris; 5, pupil; 6, 6, ciliary nerves penetrating the scle- rotic ; 7, 7, nerves passing be- tween sclerotic and choroid ; 8, 8, plexus resulting from their anastomoses ; 9, 9, ramifications extending from this plexus into the iris. 134 THE CRANIAL NERVES. lated, the pupils are dilated, while the blood-vessels are con- tracted. Mosso ' has endeavored to show a relation between the tur- gescence of the vessels of the iris and the extent of dilatation of the pupil which exists at the same time, and thus to avoid Fig. 48. — Section of the lens, etc., showing the mechanism of accommodation. (Fick.) The left side of the figure (F) shows the lens adapted to vision at infinite distances ; the right side of the figure {N) shows the lens adapted to the vision of near objects, the ciliary muscle being contracted and the suspensory ligament of the lens consequently relaxed. the apparent inconsistency in the effect of the sympathetic system upon the same type of muscular structure. Oehl ' and others claim that the sympathetic fibers, which act in antagonism to those of the third nerve upon the iris, are not derived from the ophthalmic ganglion, but accompany the ophthalmic branch of the fifth cranial nerve, and enter the eye with the long ciliary nerves ; and that, when these sympa- thetic filaments are divided, stimulation of the main sympa- thetic cords no longer causes dilatation of the pupil. He thus ascribes to the fifth cranial nerve the power of dilating the pupil, and regards the Gasserian ganglion as the source from which this power is derived from the sympathetic system. The experiments of Oehl were made upon dogs and rabbits, and have been confirmed by Rosenthal, Hensen, Volckers, and Yelpeau. The effect of these fibers of the fifth nerve is thought by these observers to be dependent upon a vasa-mo- torial influence upon the blood supply of the iris. ' C. F. Mosso, Turin, 1876. « Henle und Meissner's " Bericht," 1862. THE MOVEMENTS OF THE EYEBALL. 135 Slight oscillations of the pupil may be observed to occur synchronously with the action of the heart, and others, also, wdth the respiratory movements. These oscillations have been by some considered as an evidence that the movements of the pupil were the result of alterations in its vascularity, the iris contracting when its vessels are filled, and dilating when its vessels are empty ; but the physiological fact that the move- ments of contraction and dilatation of the pupil are noticed in the bloodless eye seems to point to some other agency than simply an alteration in the blood supply.' MOTIOKS OF THE EYEBALL. Since the third nerve is distributed to all of the muscles of the eyeball but two, the motions of the eye are largely controlled by it ; while accommodation of vision is also pro- duced by its distribution to the ciliary muscle. Some prac- tical facts may be here noted respecting the movements of the eyeball, which have not only a general interest, but a diagnostic value. The eye is virtually a ball placed in a socket, the orbit ^ " The impairment of iritic reflex action (' pupillary reflex ') was first intelligently studied in 1869, by Dr. Argyll Robertson, of Edinburgh. His observations have since been abundantly verified by numerous observers, and an exhaustive paper on the subject has been published by Professor W. Erb, of Leipsic, in the * Archives of Medicine,' Oc- tober, 1880. Robertson, and others after him, noticed that the pupils of tabetic patients did not dilate in the shadow and contract in the light, as do normal pupils, and they fur- ther observed that during the effort of accommodation there occurred a normal pupillary contraction. In other words, the reflex iris movements were abolished, while its associa- ted quasi-voluntary movements were preserved. These phenomena may be observed in almost all patients suffering from posterior spinal sclerosis, and I am in the habit of call- ing the attention of students to the symptom. In two of the patients now under my care this condition is not present, but there have been cases of abnormal sclerosis in which all the symptoms appeared in a most irregular manner." (E. C. Seguin, " Med. Record," 1881.) " The pupils in a suspected case of posterior-spinal sclerosis are to be tested in the fol- lowing manner : the patient is placed, seated or standing, facing a brightly illuminated window, and told to keep his look fixed on some distant object, such as a house or tree. By alternately closing and opening the lids, or, better, by shading the eyes with one's hand momentarily, it is easy to see if the pupils change diameter. It is of the utmost importance that the patient's intelligent assistance be secured, in order that his gaze shall remain adjusted for distance. In a given case the absence of reaction to light having been noted, we next hold up one finger or a small object within a foot of the patient's face, and bid him look at it. At once the pupils contract, and do so in proportion to the accommodative effort and the coincident convergence. When the patient looks at the dis- tant object, and relatively or absolutely relaxes his accommodation, the pupils dilate again." 136 THE CRANIAL NERVES. and the globe forming a ball-and-socket joint. In its socket joint, the eye is capable of a variety of movements ; but it can not, by any voluntary effort, be moved out of its socket. By disease, however, the position of the eyeball within the cavity Fig. 49. — Muscles of the eyeball. (Sappey.) 1, attachment of the tendon connected with the inferior rectus, internal rectus, and ex- ternal rectus ; 2, external rectus, divided and turned downward to expose the inferior rectus ; 3, internal rectus ; 4, inferior rectus ; 5, superior rectus ; 6, superior oblique ; 7, pulley and reflected portion of the superior oblique ; 8, inferior oblique ; 9, levator palpebrae superioris ; 10, 10, middle portion of the levator palpebne superioris ; 11, op- tic nerve. of the orbit may be materially altered. By pressure on the nerves distributed to its muscles, paralysis of those individual muscles may result which are supplied by the affected nerve, and the eye may thus be deflected from its normal position by the other muscles, whose motor power is unimpaired. The anatomical fact, that the muscles which move the eyeball de- rive their motor power from three sources, viz. : the third, fourth, and sixth cranial nerves, may often be made a means of determining the situation of abnormal conditions within the orbit or cranial cavity, by a thorough familiarity with the points of origin of each of these nerves, and the relations which each bears to the surrounding parts throughout the whole length of its course. THE MOVEMENTS OF THE EYEBALL, 137 It has been shown by Bonders that, though we can move the eye in almost every possible variety of inclination, we can not, by a voluntary effort, rotate the eyeball around its longi- tudinal visual axii^. The arrangement of the muscles of the eyeball would seem to permit of such a movement, but we can not by any direct effort of will bring it about by itself, although we can occasionally produce it unconsciously when we endeavor to move the eyeballs in certain special directions. During movements of the head, the eyes, if directed toward an object, may be kept stationary upon that object, in spite of such movements of the head, ' very much as the needle of the ship's compass remains stationary when the ship is turned. By this wonderful coordination of movement steadiness of vision is insured, which would be otherwise impossible.^ Straight movements. \ To depress the eye To adduct toward the nasal side. To adduct toward the malar side. Oblique movements. A TABLE SHOWING THE ACTION- OF THE OCULAR MUSCLES. [ To elevate the eye \ ^^f ^« «"Pf ^^- f Obliquus mferior. I Rectus inferior. ( Obliquus superior. Eectus internus. Rectus externus. r Rectus superior. To elevate and adduct the eye ) Rectus internus. ( Obliquus inferior. r Rectus inferior. To depress and adduct the eye } Rectus internus. ' Obliquus superior. S' Rectus superior. Rectus externns. Obliquus inferior. I Rectus inferior. To depress and abduct the eye ) Rectus externus. ( Obliquus superior. In the accompanying table,' in which the various motions of the eye are enumerated, and the combinations of muscles necessary to produce each of these individual motions are shown, it will be perceived that in the straight deflections of ' An effect due chiefly to the action of the oblique muscles of the eye. "^ Mich. Foster, " Text-Book of Physiology." ^ After Mich. Foster, op. cit. 138 THE CRANIAL NERVES. the globe of the eye never more than two muscles are required to produce them, and often only one ; while, in the oblique deflections of the globe, three muscles are always compelled to work in unison. It may furthermore Ibe stated that, to counterbalance the action of either of the oblique muscles of the eye, two muscles are always required. Suppose, for ex- ample, that the superior oblique muscle of the orbit was para- lyzed from pressure upon the fourth nerve, the eye would then be drawn downward and outward only by the combined action of the external and inferior recti muscles, although that is the direct line of action of the muscle paralyzed ; while, if that muscle should contract, and thus displace the eye downward and outward, the antagonistic muscles would be the superior and internal recti muscles, since the former would tend to draw the eye upward and inward, while the latter would also assist in drawing the eye inward. The ability to move either of the eyes independently of the other is possessed by very few individuals, although, in rare cases, such a power is present. The movements of the eye have been so arranged by Nature that the objects seen shall affect the corresponding portions of each of the two retinae, in order to insure single vision ; and, for that reason, the two eyes will be perceived to move exactly alike, each passing simultaneously to the left or to the right, upward or down- ward. It is evident, therefore, when we throw into action the rectus internus of one eye, that we use the rectus extemus of the opposite eye, and vice versa, in case the object to be fo- cused upon the retinae lies away from the median line of the head ; but, if it lies in the direct line of vision, but so close to the face as to require a muscular effort to focus it upon the retinae, then the two internal recti muscles are called into simultaneous action. Finally, in case the object to be per- ceived lies at a distance from the eyes, it becomes necessary for the eyes to be brought into nearly a condition of parallel- ism^ to accomplish which the two external recti muscles are called into simultaneous action. CENTER FOR OCULAR MOVEMENTS. 139 Such a complex coordination of movement as the various positions of the eyes demand would seem to indicate that a special arrangement had been made within the component parts of the brain to provide for its control, and thus insure rin£^' next. Tsup. r.int rum Fig. 50. — Diagram showing the axes of rotation of the eyeball. (After Fick.) The black lines indicate the direction of the power applied by each of the six ocular mus- cles. The dotted lines indicate the axis of rotation of the eyeball. The axis of rota- tion for the rectus externus and rectus internus muscles, being perpendicular to the page, can not be shown in the diagram. that harmony which is absolutely required. The experiments of Adamiik ' tend to designate the tubercula quadrigemina as provided with distinct centers, which control certain move- ments of the eyes. Thus, he finds in tJie nates (the upper portion of the tubercula quadrigemina) a common center " for both eyes, stimulation of the right side producing movements of both eyes to the left, of the left side, movements to the right ; while stimulation of the middle Hne, behind, causes a ' Quoted by Flint, Foster, and others. ' For details concerning this center, see page 58 of this volume. 140 TEE CRANIAL NERVES. downward movement of both eyes, with a convergence of the axes, and, if made in front, an upward movement with a return to parallelism, both of which effects are accompanied by the movements of the pupil naturally associated with them. The third nerve has a decided importance in affording us one means of determining the distance of objects from the retinae which perceive them, viz., the muscular sense. It has been previously stated that, in order to perceive near objects, the internal recti and the ciliary muscles of either eye are called into simultaneous action, and we soon learn to uncon- sciously estimate the amount of muscular power required to properly adjust the eye for distinct vision, and thus to use the third nerve, as well as the optic nerve, as a guide to the ac- curate determination of distance. ALTERATION OF THE POSITION OF THE HEAD FROM PARALYSIS OF THE OCULAR MUSCLES. It is a fact well known among oculists, and one which often helps them materially in diagnosis, that the defects of vision, occasioned by impairment in the power of some of the muscles, which control the eyeball, cause the patients un- consciously to assume a position of the head which tends to assist them in the use of the affected eye. So diagnostic are some of the attitudes assumed by this class of afflicted people, that the condition which exists may be told at a glance, as the patient enters a room, by one thoroughly familiar with the diseases of this important organ. The explanation of this tendency, on the part of this class of patients, lies in the fact that any loss of power in the ocular muscles immediately shows itself in the perception of every object, as it were, doubled; and it is to overcome these double iinages that patients almost instantaneously discover their ability to get rid of the annoyance by some special attitude, which, of course, depends upon the muscle which is weakened or para- lyzed. It will be necessary, in order to make you clearly under- stand the mechanism of this peculiarity, that the separate ABNORMAL ATTITUDE FROM OCULAR PARESIS. Ul action of the six muscles which directly act upon the globe of the eye be considered. The action of each of the ocular muscles may be given then, as follows, with the proviso that many of the motions of the eye are not the result of the contraction of any single muscle, but often of a number acting either in unison or suc- cessively. The superior oblique muscle turns the eye downward and outward. The inferior oblique muscle turns the eye upward and outward. The superior rectus muscle turns the eye upward and inward. The inferior rectus muscle turns the eye downward and inward. The internal rectus muscle turns the eye directly inward. The external rectus muscle turns the eye directly outward. This statement as to the above muscles reveals nothing which would not be immediately suggested by the insertion of each, with the exception of the superior and inferior recti muscles, which, besides the action which their situation would naturally suggest, tend also to draw the eyeball in- ward^ on account of the obliquity of the axis of the orbit and the same obliquity of the muscles, since they arise at the apex of the orbit. The action of the oblique muscles is, as any one familiar with their origin and insertion would naturally sur- mise, to control the oblique movements of the eyeball. Now, as soon as any one of these six muscles becomes pressed upon and weakened by the presence of tumors, in- flammatory exudation, syphilis, or other causes, the patient at once perceives double images, and, in order to get his eye into such a relative position with that of the healthy side as to enable them both to focus upon the same object in a natu- ral manner, the patient soon learns to so move his head as to compel the two eyes to look in parallel directions. A very simple rule can be suggested by which you may be enabled, not only to tell in what direction a patient would move 142 THE CRANIAL NERVES. his head in case any special muscle be rendered weak or utter- ly useless, but also to diagnose the muscle affected, when you look at the patient, without any knowledge of his history. The rule may be thus stated : In paresis of any of the ocu- lar muscles^ the head is so deflected from its normal posi- tion that the chin is carried in a direction corresponding to the action of the affected muscle. Thus, in paresis of the external rectus,' the chin would be carried outward toward the injured muscle ; while, in paresis of the internal rectus muscle, the head would be turned away from the side on which the muscle fails to act. In case the superior oblique muscle is impaired, the chin would be carried downward and outward ; while, in the case of the inferior oblique muscle, the chin would have to be moved upward and outward to benefit the vision of the patient. The. supe- rior and inferior recti muscles, when impaired by disease or other causes, would likewise create a deflection of the head in a line corresponding to that of their respective actions. CLINICAL POINTS OF INTEREST PERTAINING TO THE THIRD NERVE. Paresis of the external and internal recti muscles causes, in addition to the facts already described, another point of very great value in diagnosis, viz., an alteration in the apparent size of the objects seen from what they would be in health. The condition of vision, termed by oculists " megalopsia^^ or '-'- macropsia^^'^ signifies paresis of the external rectus; while the opposite condition, called "m^croJ!?5^a," indicates loss of power in the internal rectus muscle. In the former of these conditions, the objects seen by the patient seem to be greater in point of size than the intelligence of the patient assures him is the case ; while, in the latter, objects seem smaller to the patient than they really are. To explain to you just how these variations of vision are ' While this statement would be absolutely true in theory in all cases, we must acknowledge, as a clinical fact, that patients leam to utterly disregard the image in the affected eye, when the internal or external rectus is the scat of paresis, and to use the nor- mal eye only for the purposes of vision, thus rendering this attitude of the head less diag- nostic than when the oblique muscles are affected. MEGALOPSIA AND MICROPSIA. I43 accomplished may require a more extended discussion of the physiological problems of vision than an anatomical discus- sion can properly deal with ; but, to understand it, you must know that the apparent size of any object depends upon the ability of the person to properly and accurately appreci- ate the angle formed between rays of light coming from the object and entering the pupils of each eye, or, in other words, the distance at which the object is placed from the retina. Now, in the case of paresis of the external rectus muscle, the object is caused to appear nearer to the eye than it really is, and thus to be larger than normal vision would cause it to seem, since the angle of the axes of vision is greater ; while, in case of the paralysis of the internal oblique, the object is apparently much farther removed from the eye than it really is, and thus the intelligence construes it as of smaller size than it would if the visual perceptions were normal. There is only one other condition of the eye where the size of objects perceived by the retina is either increased or mark- edly diminished, if the actual size be taken as a standard of measurement, and this condition is one of inflammation of the choroid coat of the eye. It is a well-recognized fact that, in the effusive form of choroiditis, objects are perceived as much smaller than they really are, while in cicatricial choroiditis the size of the object is magnified. These phenomena can not be explained as the result of a change in the angle of the axis of vision, since nothing exists to disturb the perception of distance ; but it is attributed to a separation, in the one case, and to an aggregation in the other, of the cones of the retina. The eye, by constant use, has become enabled to partly estimate the size of objects by the number of cones in the retina w^hich are covered by the image of the object. Thus, when, from causes such as have been mentioned above, the elements of the retina are either huddled more closely to- gether by a cicatrix of the choroid coat of the eye, or dissem- inated over a larger space than they normally occupy by an effusion of the choroid coat, the number of cones covered by 144 THE CRAMAL NERVES. the image thrown upon the retina is either increased, thus apparently magnifying the size of the object, or the number of cones affected is decreased, and thus the size of the object seen is apparently diminished. Fig. 51. — A. Vertical section of tJie retina. B. Connection of the rods and cones of (H. Miiller.) the retina with the nervoits elements. (Sappey.) A. 1, 1, layer of rods and cones; 2, rods; 3, cones; 4, 4. 5, 6, external granule layer; 7, inter-granule layer (cone-fiber plexus); 8, internal granule layer; 9, 10, finclv granular gray layer; 11, layer of nerve cells; 12, 12, 12, 12, 14, 14, fibers of tin optic nerve ; 13, membrana Hmitans. B. 1, 1, 2, 3, rods and cones, front view; 4, R, 6. rods, side view; 7, 7, 8, 8, cells of the external and internal granule layers ; 9, cell, connected by a filament with sub- jacent cells; 10, 13, nerve cells, connected with cells of the granule layers; 11, 21, filaments connecting cells of the external and internal granule layers (12 is not in the figure); 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, a rod and a cone, con- nected with the cells of the granule layers, with the nerve cells, and with the nerve fibers. In cases where complete blindness, even to the sensation of light, exists, as sometimes occurs in amaurosis, ' the eyes ' For the causes of this condition, see page 127 of this volume. PARALYSIS OF THE THIRD NERVE. I45 remain fixed and immovable, gazing steadily forward, even when objects are made to pass before tHe vision ; while in cases of partial blindness, which prevent the perception of outline, but still allow of the perception of passing objects between the light and the retinae, by the shadow which they throw, the eye involuntarily moves in a direction which cor- responds to that of the moving object. Cases in which the third nerve has been impaired by pres- sure or disease, or totally destroyed by section, are character- ized by a falling of the upper eyelid over the pupil,' and an inability to raise it, owing to the inaction of its levator mus- cle, so that the eye appears constantly half shut. This con- dition is known by the name of "ptosis.'^'' The movements of the eyeball are also nearly suspended, and permanent ex- ternal strabismus takes place, owing to the paralysis of the internal rectus muscle, while the external rectus, animated by a different nerve, preserves its activity. From paralysis of the fibers distributed to the iris, a dilatation of the pupil is also produced, and accommodation of the injured eye for near objects is no longer performed. While the upper eyelid is partially raised by the levator palpebrse muscle, which is supplied by the third nerve, it is also raised by means of muscular fibers, which are governed by the cervical sympathetic. A similar set of fibers exists in the lower eyelid, and is governed by the same nerves ; and it is probably through the influence of the sympatJietic system that the eye is opened. In the act of wdnking, where the shutting of the eye is usually affected more rapidly than the opening, a contrast is afforded between the action of the cra- nial nerves and those of the sympathetic, since closing of the eye is performed by the facial nerve." External strabismus may often occur without the condi- tion of ''ptosis" being present, the filament to the levator palpebrse muscle not being affected. When all the muscles supplied by the third nerve are ^ So marked is this deformity that the upper lid frequently almost touches the lower lid. ^ 'M\c\i. Foster, op. cit. 146 THE CRANIAL NERVES. paralyzed, the globe of the eye is slightly protruded, from relaxation of most of its muscles. In strabismus, or squint, an optical defect' is usually present. So large is the percentage of optical error in those cases where the eyes turn inward toward the nose, that this condition seldom exists without an accompanying hyperopia or far-sightedness, due to a diminution of the antero-posterior axis of the eye ; while in external squint, where the eye looks away from the nose, the opposite condition of myopia, or near-sightedness, is often present, but perhaps not in as large a percentage of cases as in the opposite deflection of the eye. For this reason, operations are often of little benefit when performed for the relief of strabismus, unless the error in vision is accurately determined and corrected by the appro- priate lenses. DISEASES OF THE OCULAR MUSCLES AND THEIR CAUSES. The muscles of the orbit may present the conditions of spasm, contracture, motor irritation, or paralysis. The condition of " nystagmus " is characterized by clonic spasm of the external ocular muscles, and by peculiar oscilla- tions or involuntary movements of the organ. It is always a bilateral affection, and its starting-point, according to the ex- periments of Adamuk and Ferrier," seems to be situated within ^ See Haynes Walton, Stellwag, and others. In speaking of this optical defect, depen- dent upon simple hyperopia, Dr. Loring says, in an article previously quoted in this vol- ume : " I have known boys of eight or ten years of age to beg their parents to let them undergo the pain of an operation to rid themselves of a deformity which subjects them so often to the unfeeling remarks of their elders, usually friends of the family, as well a the uneuphonious but expressive titles bestowed upon them by their own contemporaries, of goggle-eye and cock-eye. Nor does this end with childhood. The deformity is a dis- advantage to him through life. It pursues him in his business and in his profession. Cheated of feature by dissembling nature, he is often thought to be dissembling himself, when nothing is further from his thoughts. How often do we hear people say of another, whom we know to be perfectly upright and trustworthy, that they do not like him because he never looks them squarely in the face ! And it is a little curious that precisely here it is that the lesser degrees of the trouble produce the most effect. That peculiar expression which people complain so much of is generally due to a deviation in the axes of the eyes — a slight convergence, which is never very conspicuous, and at times only to be detected by a trained eye, but which, nevertheless, produces in all a very disagreeable impression, although not marked enough to betray its cause. ' See page 68 of this volume. CAUSES OF PARALYSIS OF THE THIRD NERVE. 147 the anterior tubercula quadrigemina. It may be produced by causes affecting either the central nerve ganglia, the periphe- ral nerves, the refracting media of the eye, or the retina. We thus find it existing in connection with meningitis, hydro- cephalus, etc., in uterine diseases, worms, dentition, caries of the teeth, etc., and in some of the diseases of the eye or optic nerve. Spasm of the fibers of the iris is observed, in rare cases, to exist in connection with some irritative condition of the cere- bro-spinal system, which has involved the cilio-spinal center of the spinal cord.' By contracture of a muscle is meant a permanent shorten- ing, in contrast to its temporary shortening when under the ordinary influence of the motor stimulus. It occurs, in the ocular group of muscles, as the result of the direct irritation following some pathological process, at a seat more or less distant from the orbit ; or as the effect of prolonged paralysis of some of the antagonistic muscles. In those cerebral and spinal conditions in which convulsive attacks are produced, and in attacks of hysteria, the evidences of well-marked motor irritation of the ocular muscles are often observed. Paralysis of the ocular group of muscles may vary in degree, thus constituting either paresis or true paralysis ; also in extent, thus affecting all the muscles supplied by the third nerve, and often the fourth and sixth nerves as well, or, again, only separate muscles ; and finally in duration and its sus- ceptibility to treatment. This symptom may be either an initial symptom, or a complication of some central disease, or the result of peripheral causes. Paralysis of the muscles supplied by the third nerve is most frequently produced by the following causes : Circum- scribed meningeal processes at the base of the skull ; tu- mors, softening, and haemorrhage of the cerebral peduncles ; softening and haemorrhage of the cerebral ganglia ; syphi- ' For details as to the situation and function of this center, the reader is referred to subsequent pages of this volume. 148 THE CRANIAL NERVES, lis (affecting the cranial or orbital cavity) ; orbital tumors ; diphtheria ; and, finally, aneurisms of the carotid (as reported by Lebert '). In the development of ataxia^ the third nerve may become paralyzed simultaneously with other nerves of the cranium, or, possibly, without other nerves being affected, and the same condition may follow the prolonged use of co- nium or gelsemium. When the paralysis of the third nerve is produced by intra- cranial lesions, the paralysis is liable to be bilateral or to tend toward a symmetrical development as the disease progresses ; while the fourth and sixth nerves are often subsequently af- fected. There are also other symptoms, of great value in deciding upon the existence of intra- cerebral disease, which may be present, such as the coexistence of cephalalgia, ver- tigo, symptoms of neuro-retinitis, disturbances of speech and of the intellectual faculties, convulsive movements of a local or general type, a sense of weight in the limbs, or, possibly, the presence of paresis or paralysis of the muscles of the extremities. '' A very large proportion of tabetic patients tell of past or present diplopia, and, in a certain number of cases, the ocular paralysis precedes the pains and ataxia by several years. So true is this statement, that it has become an established prac- tice with neurologists and ophthalmologists to suspect poste- rior spinal sclerosis in adults who present themselves with strabismus, diplopia, or ptosis. In such a case we should carefully question the patient about the occurrence of fulgu- rating pains, and test the pupillary and tendinous reflexes. I need hardly add that another obligatoiy line of inquiry in such cases is with reference to symptoms of syphilis." ' The same remarks apply to atrophy of the optic nerve, which is occasionally an early symptom. It is not infrequent for lesions of the spinal cord to pro- duce paralysis of the ocular muscles. The presence of such an exciting cause may be surmised by the coexistence of vague neuralgias in the branches of the cervical or brachial plexuses, ' Quoted by Rosenthal. « E. C. Seguin, " Med. Record," 1881. THE FOURTH C RACIAL NERVE. I49 or in the sciatic nerves ; of abnormal sensations in tlie back, knees, and soles of the feet ; seminal emissions, frequent or prolonged erections, or diminished sexual power; extreme sensitiveness to moisture of the atmosphere or winds ; a tendency to fatigue, often present after a night's repose; and an increase in the galvano-excitability of the main nerve trunks. Paralysis of the ocular muscles may accompany glosso- lahio-pTiaryngeal paralysis (Duchenne's disease'), if the cen- ter for the movements of the eye be affected at the same time as the centers of the muscles of speech and deglutition ; in this case, the third and sixth nerves are frequently affected simultaneously. The same condition of the ocular muscles may also accompany ataxic symptoms of cerebral origin. Rheumatism may produce ocular paralysis. This cause is to be suspected w^hen no symptoms exist which seem to point to local trouble in the orbit or brain. It is found to affect the motor oculi and the abducens nerves more frequently than the patheticus. Diplopia and strabismus are often the first symptoms of ceiebral diseases or ataxia, since they may appear before the other parts of the muscular system are affected. If they show, at times, a tendency toward spontaneous retrogression, and again return with the simultaneous occurrence of neuralgic pain, the development of a cerebral lesion is rendered still more probable. THE FOURTH (TROCHLEAR OR PATHETIC) NERVE. The apparent origin of this nerve is from the superior peduncle of the cerebellum^ and it then winds around it, pass- ing close to the posterior border of the pons Varolii. The deep origin of the fibers may be traced to four different sit- uations, as follows : 1, some fibers to the substance of the ' The symptoms of this condition will be found mentioned in more detail in connec- tion with the hypo-glossal nerve. 12 150 THE CRANIAL NERVES. peduncle ; 2, other fibers to the valve of Vienssens, where they are lost, with the exception of a few, which can be traced to the frenulum ; 3, a few fibers to the tuhercula quadrige- mina ; 4, a large bundle, which pass inward toward the median line and then decussate with corresponding filaments of the opposite side. This decussation of the fibers of the nerve is for the same physiological reason, as was mentioned in connection with the preceding nerve, viz., to afford harmony of action between the two sides, when the eyes are compelled to remain fixed upon an object during move- ments of the head. From the point of appar- ent origin, the nerve passes forward along the outer wall of the cavernous sinus, where it lies Ijelow the third nerve and above the ophthalmic branch of fhe fifth nerve^ and escapes from the cavity of the cranium, through the highest part of the sphenoidal fissure, into the cavity of the orbit. The question of the func- FiG. 52. — Distnbution of Ihe patheticus. (Hirschfeld.) I, olfactory nerve ; II, optic nerves ; III, mo- tor oculi communis ; IV, paihdicus, bi/ iJie side of the ophthalmic branch ofthejifth^ and passing to the superior oblique muscle; VI, motor oculi cxternus ; 1, ganglion of Gasscr; 2, 3, 4, 5, 6, 7, 8, 9, 10, ophthal- mic division of the fifth nerve, with its branches. tion of this nerve resolves it- self simply into the mode of action of the superior oblique muscle. This muscle arises just above the inner margin of the optic foramen, and passes forward along the upper wall of the orbit, at its inner angle, to a little cartilaginous ring, which serves as a pulley for its tendon. Its tendon becomes rounded just before it passes through this ring, where it makes a sharp curve, passes outward and slightly backward, and be- comes spi-ead out, to be attached to the globe, at the superior and external part of its posterior hemisphere. It is, there- fore, the direct antagonist of the inferior oblique muscle. THE FIFTH CRANIAL NERVE. 15^ In its function, it is purely a motor nerve, but it receives a few recurrent fibers from the fifth nerve, which are sen- sory. AVhen this nerve is paralyzed, the position of the eye shows no apparent change, except when the head is moved from side to side, in which case the eye moves loitli the liead ; the absence of the usual compensating movement of the eye, which accompanies all the movements of the head, being de- stroyed in consequence of the paralysis of the superior oblique muscle, which greatly assists in this act. The patient also sees a double image, whenever attempts are made to look straight forward, or at objects situated toward the paralyzed side ; but the image becomes a single one when the head is turned toward the sound side to view any object ; hence this abnormality of attitude of the head is usually present/ THE TKIGEMINUS OE FIFTH NERVE. This important nerve has its apparent origin within the cranium from the lateral aspect of ih.Qjpons Varolii, although its deep fibers have been traced by Lockhart Clarke to two distinct nuclei, situated in the floor of the fourth mntricle near to the gray tubercle of Rolando.'' It is a mixed nerve, having a distinct motor and sensory root ; and thus pos- sesses both afferent fibers, through which sensory impres- sions are transmitted to the brain, and efferent fibers, by which motor impulses are transmitted from the brain to the periphery of some branches of the nerve. The intimate relations which the nerve bears with the points of origin of the sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth cranial nerves in the floor of the fourth ventricle possibly explain many of those phenomena which are considered as reflex in character, and whose starting-point ^ For other examples of this diagnostic guide in paralysis of ocular muscles, sec pre- vious pages upon the third cranial nerve. - See pages which relate to the medulla oblongata. 152 THE CRANIAL NERVES. seems to depend upon some irritation of the fifth nerve by- means of various branches. The two roots of this nerve pass forward, side by side, as far as the petrous portion of the temporal bone. At this ' point a marked enlargement, called the ganglion of Gasser, is developed upon the sensory root ; and subsequently this root] Fig. h^.—Ophthnhrur >liris},r,t oj Ihcji/lli. (Ilirschrda.) 1, ganglion of Gasser; 2, ophthalmic division of the fifth ; 3, lachrymal branch ; A, frontal branch ; 5, external frontal ; 6, internal frontal ; 7, fiupra-trochlcar ; 8, naaal branch; ^^ external nasal; 10, internal nasal; 11, anterior deep temporal nerve; 12, middle deep temporal nerve; 13, posterior deep temporal nerve; 14, origin of the superficial temporal nerve ; 15, great superficial petrous nerve. I to XII, roots of the cranial nerves. divides into three large nervous trunks called, resi)ectively, the ophthalmic, the superior maxillary, and the inferior max- illary nerves, which escape from the cavity of the cranium through different foramina.* The motor root accompanies the inferior maxillary nerve until it has escaped from the cranium, when it unites with it. ' The sphenoidal fissure, foramen rotundum, and foramen ovale respectively afford a passage for these branches from the cranium. FUNCTION'S OF THE FIFTH NERVE. 153 TABLE OF THE DISTRIBUTION^ OF THE FIFTH CRAJs^IAL KERVE.' fa. OPHTHAL- MIC NERVE. r (1) Lachrymal branch. (2) Frontal branch. \ guP'a-oi'bital nerve / fcupra-trochlear ner [^ (3) Nasal branch. h. SUPERIOR MAXILLARY^ In the sj)hcno-maxil- lary fossa. NERVE. In the infra-orbital \ ( hjupra -trochlear nerve. r Ganglionic nerve (to ciliary ganglion). Long ciliary nerves. Inf ra-troclilear nerves. Internal set. To septum of nose. ( To mucous mem- External set. -j brane and integu- t ( ment of nose. ' Orbital or Temporo-malar nerve. Spheno-palatine nerves (to Meckel's gan- glion). Posterior dental ( ^"P^^^,^'^^ ^^^ntal nerve. i branches. ( Deep dental branches. c. INFERIOR MAXILLARY NERVE. canal. On the face. From the trunk. anterior From the posterior ti"unk. s Anterior dental nerve. Palpebral branches. Nasal branches. Labial branches. r (1) Masseteric branch. I (2) Deep temporal. \ ^°*f"?^ ^Z'^^^^- I ( Posterior branch. (3) l3uccAL branch. (4) Pterygoid. \ Internal branch. ^ ' ( External branch. (1) Auriculo - tem- j Auricular. PORAL nerve. ( Temporal. (2) Gustatory nerve. f Mylo-hyoid. (8) Inferior dental] Incisor. NERVE. 1 Mental, t Dental. From anatomical points which have been mentioned, and also by the above table, the fact is shown that the ophthalmic and the superior maxillary nerves possess no motor power, while the inferior maxillary nerve is both motor and sensory in its function. It has been mentioned in previous pages, however, that a vaso-motorial influence is possessed by the ophthalmic nerve, and also a direct power of dilating the jjupils ; but these effects are unquestionably dependent upon filaments given to it by the sympathetic nerve. The ultimate distribution of the three branches of the fifth nerve may possibly be made more clear by grouping together the efferent and afferent fibers, and thus separating the parts Copied from "Essentials of Anatomy" (Darling and Ranney), New York, 1S80. 154 THE CRANIAL NERVES. Fig. 54. — A diagram of the dutribution of tlie fifth nerve} the crus cerebri ; 2, the sensory root of the nerve ; 3, the motor root of the nerve ; 4, the Oasserian ganglion^ upon the sensory root only ; 6, the ophthalmic nerve, passing through the sphenoidal fissure ; 6, the superior maxillary nerve, passing through the foramen rotundum, to enter the spheno-maxillary fossa ; Y, the inferior maxillarif nerve, passing through the fora^ncu ovale in company with the motor root, which soon joins it ; 8, a filament sent backward from the ophthalmic nerve to the tento- rium cerebelli ; %, t\vQ frontal nerve ; 10, the lachrymal nerve ; 11, the nasal nerve; 12, the supra-orbital nerve, passing tii rough the foramen of the same name ; 13, the s^iipra-trorhlrar nerve; 14:, the long ciliary nei'ves to the iris; 15, the knticidar, or ciliary ganglion ; 16, the temporo-malar nerve, showing its division into the temporal branch and the malar branch; 17, the spheno-palatine nerves, going to Meckel's gan- glion ; 18, the posterior dental nerves, given off just before the superior maxillary nerve enters the infra-orbital canal, after passing throuajh the spheno-maxillary fossa ; 19, the anterior dental nerves, given off in the antrum ; 20, the nemo-palatine nerve, es- caping at the anterior palatine foramen, after passing through the antrum; 21, the anterior palatine nerves, after escaping from the posterior palatine foramen ; 22, the deep tempyral nerve; 23, the masseteric branch ; 24, the brjiceal branch, which often also supplies the external pterygoid muscle; 25, the pterygoid branch, going chiefly to the internal pterygoid muscle ; 26, the posterior palatine nerves, after escaping from the posterior palatine foramen, going to the muscles of the soft palate ; 27, the auriculo-temporal nerve, splitting and thus embracing the middle meningeal artery ; 2S, the gustatory or lingua' nerve, distributed to the anterior two thirds of the tongue ; 29, the inferior dental nerve, passing through the inferior dental canal, beneath the teeth of the lower jaw ; 30, the myl^-hi/oid nerve, a branch of the inferior dental nerve; 31, the chorda tympani nerve, joining the gustatory nerve, and possibly bring- ing to it the perception of taste ; 32, the middle meningeal artery ; ^Z, the fibers going to the carotid and cavernous plcxusics of the sympathetic system; 34, the Vidian nerve, going from Meckel's ganglion to the Vidian canal. Ganglia of the fifth nerve. — L, The lenticular ganglion, sending fibers to iris and ciliary muscle ; c, the Gafsc- rixn ganglion ; o, the ofic ganglion, lying on the inferior maxillary nerve below the foramen ovale ; s, the submaxillary ganglion, connected with the gustatory and chorda iympani nerves ; m, Meckel's ganglion, lying in the spheno-maxillary fossa. ^ Modified fr:m Flower. DISTRIBUTION^ OF THE FIFTH NERVE 155 whicli are supplied alone with sensation from those to which the motor root is eventually distributed. The efferent fibers of the fifth pair give motor power to the muscles of mastication, viz., the temporal, masseter, and v*,"'«^\l Fia. 55. — Infci'ior maxillarif division of the ff(h . (Ilirschfeld.) 1, branch from the motor root to the masseter muscle; 2, filaments from this branch to the temporal muscle ; 3, buccal branch ; 5, 6, 7, branches to the muscles ; S, aiiri- culo-temporal nerve ; 9^ temporal branches ; \0, auricular branches; l\, anastomosis u'ith the facial nerve ; 12, lingual branch ; 13, branch of the motor root to the mylo- hyoid muscle; 14, 15, 15, inferior dental nerve, loith its branches ; 16, mental branch; 17, anastomosis of this branch ivith the facial nerve. pterygoids ; also to the mylo-hyoid and anterior belly of the ■fcigastric, and to the tensor palati and tensor tympani. They f thus control not only the physiological act of mastication, but also, to some extent, the acts of deglutition and hearing. These fibers furthermore afford a vaso-motor influence over various vessels in certain regions of the head and face. Secre- tory fibers to the lachrymal gland, and, according to some 156 THE CRANIAL NERVES. authors, to the parotid and submaxillary glands, by means of fibers derived from the facial nerve (through the chorda tym- pani branch), are attributed to the trigeminus. By these fibers, the secretions necessary to the perfect performance of the parts supplied by the fifth nerve are also placed under its control, thus illustrating again that beautiful law of Nature in arranging the nerves in accordance with harmony of action. Beside the efferent fibers possessed by the fifth nerve, there exist in addition certain unnamed fibers which control the proper nutrition of the eye, nose, and other portions of the face. These latter fibers are not as yet fully ascertained so as to be described in detail, but their existence seems indi- FiG. 56. — Sujyerior maxillary division of the fifth. (Hirschfeld.) 1, ganc^lion of Gasser; 2, lachrymal branch of the ophthalmic division ; 3, superior mar- illari/ division of the fifth ; 4, orbital brayich ; 6, lachrymo-palpehral filament ; 6, malar branch ; 7, temporal branch ; 8, splleno-palatine ganglion ; 9, Vidian nerve ; 10, great superficial petrosal nerve ; 11, facial nerve ; 1 2, branch of the Vidian nerve ; 13, anterior and two posterior dental branches \ 14, branch to the mucous membrane of the alveolar processes; \1S^ terminal branches of the superior maxillary division \ 16, branch of the facial. cated by the fact that, after section of the fifth nerve, the cornea becomes cloudy ; the whole eye becomes inflamed, only to subsequently disorganize ; the mucous membrane of the nose is similarly destroyed, and ulcers frequently make their appearance upon the mucous membrane of the lips and gums. Snellen, however, considers these changes as the ef- AFFERENT FIBERS OF THE FIFTH NERVE. 157 fects of the mechanical irritation of dirt, which the mucous membranes, no longer possessing sensibility, are unable to perceive. The afferent fibers of the fifth nerve afford general sensa- tion to the entire skin of the head and face, except in the occipital region and the back and lower part of the ear,' Fig. 57. — Superficial branches of the facial and thcffth. (Kirschfeld.) 1, trunk of the facial ; 2, posterior auricular nerve ; 3, branch which it receives from the cervical plexus ; 4, occipital branch ; 5, 6, branches to the muscles of the ear ; 7, digris- trie branches ; 8, branch to the stylo-hyoid muscle ; 9, superior terminal branch ; 10, temporal branches ; 11, frontal branches ; 12, branches to the orbicularis palpebrarum ; 13, nasal, or suborbital branches ; 14, buccal branches ; 15, inferior terminal branch ; 16, mental branches ; 17, cervical branches ; 18, superficial temporal nerve (branch of the fifth); 19, 20, frontal nerves (branches of the fifth); 21, 22, 23, 24, 25, 26, 27, branches of the fifth ; 28, 29, 30, 31, 32, branches of the cervical nerves. and also to the mucous membranes of the mouth, with the exception of the posterior pillar of the fauces and the poste- 1 Hilton. 158 THE CRANIAL yBRVBS. rior third of the tongue, which derive their sensation by means of the glosso -pharyngeal nerves. The accuracy of this statement, as regards the distribution to the integument of the ear, which is now accepted by most of the anatomical authors of the present day, was strangely attested to by facts brought under the notice of John Hilton,' w^ho was thus enabled clinically to verify the exact distribu- tion of the fifth nerve to the pinna and the auditory canal. It seems that an attempt was made by a criminal to kill his wife by cutting her throat, but that the attempt was not suc- cessful, and resulted in severing the auricular branch of the second cervical nerve, which supplies the ear, as well as the fifth cranial nerve. An opportunity was thus afforded to ex- amine, by the use of nsedle points, the state of sensibility of the different portions of the ear, and to decide, by the loss of sensibility, the exact regions which the second cervical nerve supplied. It was thus proven that the uppe?' and ante- rior part of the ear, and also the auditory canal, was sup- plied by the fifth cranial nerve ; and that, therefore, these parts are in direct nervous communication with the forehead, temple, face, nose, teeth, and the tongue. It can thus be easily understood why pain in the auricular region, as evidenced in cases recited later on, may prove a most valuable diagnostic sign of irritation of some of the other branches of the fifth nerve, distributed to the regions which are associated by means of this nerve with the ear, although apparently having no anatomical relation with it. In the partly diagrammatic representation of the distri- bution of the nerves to the cutaneous surface of the head, the outlines of the various regions, represented as supplied by the different nerves, are as nearly accurate as careful investi- gation can determine them." It will be perceived that nine, out of the fourteen regions mapped out upon the head and neck, are supplied with sensation by some of the branches of > " Rest and Pain," London (New York, 18 TO). * As the boundaries of the regions supplied by any nerve gradually shade off into neighboring regions, it is not well to rely upon the cxircme area of any region in testing the special sensibility of any nerve. CUTANEOUS BLANCHES OF THE FIFTE NERVE, 159 the fifth cranial nerve, while the remaining five are supplied by branches of the cervical plexus, with the exception of that region to which the great occipital nerve is distributed. It can easily be understood, from what has already been Fig. 58 — The nervous distribution of the head. (After Flower, but slightly modified.) 1, region supplied by the supra-orbital branch of the fifth nerve; 2, region supplied by the mpra-lrochUar branch of the filth nerve ; 3, region supplied by the infra-troch- lear branch of the fifth nerve ; 4, region supplied by the infra-orbital branch of the fifth nerve ; 5, region supplied by the buccal branch of the fifth nerve ; 6, region sup- plied by the mental branch of the fifth nerve ; 7, region supplied by the superficial cervical from the cervical plexus ; 8, region supplied by the great auricular from the cervical plexus ; 9, region supplied by the iemporo-malar bianch of the fifth nerve ; 10, region supplied by the lachrymal branch of the fifth nerve ; 11, region supplied by the auriculo-tcmporal htdincXi of the fifth nerve; 12, region supplied by the great occipital (a spinal nerve) ; 13, region supplied by the small occipital from the cervical plexus ; 14, region supplied by the supi-a-dlavicular from the cervical plexus. said as to the manner of employing the nerves as guides to diagnosis, that a careful study of the limits of each of these regions of the head may often enable the physician to explain symptoms which might otherwise seem obscure ; and also enable him to use the symptom of local pain, whenever pres- ent, as a signal which Nature often gives of disease in parts possibly far removed from the seat of pain, but still inti- mately connected to it by means of its nervous supply. EFFECTS OF SECTIOX OF THE FIFTH :N^EEVE. Many points of practical value dependent upon the fifth nerve can be better understood when the effects of its divis- ion have been considered in detail. If the fifth nerve be divided, sensation is immediately destroyed in all those 160 THE CRANIAL NERVES. portions of the head and face to which the efferent nerves are distributed ; the power of mastication is lost ; the secre- tions of the lachrymal, parotid, and submaxillary glands are rendered deficient ; the act of deglutition becomes imper- fect, since some of the muscles required for its performance are paralyzed, and since the tongue is unable to perceive the bolus of food, and therefore can not x>roperly direct its movements ; and, finally, Jiearing is, to a certain extent, impaired, since the tensor tympani muscle ' has lost its motor power. In addition to these direct effects of section, secondary results are manifested in those forms of ulceration which have been previously referred to, and, eventually, in the de- struction of sight and smell. It may be noticed that the effect of section of the fifth nerve upon the special sense of taste has not been mentioned. It was formerly supposed that the gustatory fibers of the fifth nerve afforded the sense of taste to the anterior two thirds of the tongue ; but it is now urged by many that the fifth nerve is simply a nerve of sensation to that organ, and that its fibers are employed exclusively in the appreciation of the sensations of touch and feeling, while the true gustatory fibers of that portion of the tongue are derived from the chorda tympani branch of the facial nerve. In support of this view, cases have been observed where the chorda tympani has been affected, either by disease or in consequence of injury within the middle ear, and the sense of taste has been impaired ; but, on the other hand, cases have been also recorded where the fifth nerve was alone diseased, and yet taste was destroyed in thf^ anterior two thirds of the tongue. It is such cases as tli< latter that still lead some physiologists to believe that the chorda tympani nerv^e only controls t\\eflow of the saliva^ and that impairment of this secretion impairs or destroys the spe- cial sense of taste afforded by the gustatory branch of the fifth nerve. ' According to Lticac's recent experiments (" Berlin, kiln. Wschr.," 1874), the tensor tympani muscle presides over the accommodation for musical tones. NEURALGIA OF THE FIFTH NERVE. lei CLIXICAL POINTS AFFOKDED BY THE FIFTH NERVE. The fifth nerve may be the seat of neuralgia, spasm, or paralysis. The type of neuralgia (called tic-douloureux, the facial pain of Fothergill, and " prosopalgia ") dependent upon the fifth nerve affects only the sensory trunks ; the spasms may be of a tonic or clonic type, and are, of course, confined to the muscles supplied by the motor branches of the nerve ; while the paralytic condition can affect the sensory trunks, producing anaesthesia of the parts to which the affected nerve is distributed, or the motor filaments may be impaired, thus destroying the power of normal movement in the muscles of mastication and the mylo-hyoid. So many points of clinical interest and practical value pertain to these various condi- tions that each will be considered somewhat in detail. NEURALGIA OF THE TRIGEMINUS NERVE. The various forms of tic-douloureux are so Commonly met with, and prove so obstinate to treatment, as well as distress- ing to the patient, that a practical knowledge of the disease can not be gained without a careful study of the various causes which have been found to produce it. Among the reported cases of this affection, there have been discovered, as exciting causes, the following conditions : Tumors of the middle fossa of the skull or of the base of the brain, producing neuralgia so long as irritation only is produced, but anaesthesia when degeneration of the nerve trunks begins ; accumulations of pus within the cranial cav- ity ; tumors of the pons Varolii ; morbid processes in the regions adjacent to the ganglion of Gasser ; and aneurism of the internal carotid artery ' within the sella turcica. Diseases of the cervical portion of the spinal cord, if high up, may cre- ate neuralgia of the fifth pair, by irritating the fibers of that nerve which arise from the lower part of the medulla. Peri- ostitis of the bony orifices, through which the various branches of the fifth nerve pass, may create such pressure as to produce ' Romberg's case. 162 THE CRANIAL NERVES. the most severe and persistent neuralgias ; for this reason the supra-orbital, infra-orbital, zygomatic, superior and inferior dental branches are more liable to be the seat of pain than the branches which pass through such large openings as the sphenoidal and spheno-maxillary fissures.' Exostoses of the bones, especially of the upper and lower jaws, may create the most severe type of neuralgia by pressure upon the neighbor- ing nerve trunks. Exposure to cold or dampness will pro- duce it, being one of the most frequent of the trivial causes. Finally, inflammatory changes in the ganglia " attached to the nerve, the enlargements and nodosities found upon resected nerves, an exostosis of a wisdom tooth," caries and osteo- phytes of the bony canals through which branches of the nerve pass, and neuroma of the ganglion of Gasser protrud- ing through the foramen ovale,* have been known to produce the most severe neuralgia. The symptoms of tic- douloureux are of the most distressing character. The pain is usually extremely violent, and the patients will describe it to you as of a burning, piercing, or shooting character. It is liable to be, at first, paroxysmal ; but, if due to organic disease, it may gradually become more or less constant. The continuous pain is, however, usually limited to certain well-defined spots of extreme sensitiveness to pressure, which the patient can readily point out to you (the "puncta dolorosa " of Yalleix). Thus, the first branch of the trigeminus (the ophthalmic) presents six such points, each indicating some one of its subdivisions. These are situated, respectively, over the supra-orbital foramen ; in the center of the upper eyelid ; a frontal point over the escape of the nerve of the same name ; one at the outer angle of the eye, for the lachrymal branch ; and two at the inner angle of the eye, upon the nose, representing the inferior trochlear and the ethmoidal nerves. In the region supplied by the superior maxillary nerve and its branches, there may exist a malar point, an infra- ^ Ilyrtl, as quoted by Rosenthal. ' Cases of Carnochan and Wcdl. * Thompson, as quoted by Rosenthal. ^ Chouppe's case. NEURALGIA OF THE FIFTH KERVE. 163 orbital point, a point in the palate, and one on the gum of the upper jaw. In the region of the inferior maxillary nerve, the points of tenderness are situated in front of the tragus of the ear (the temporal point) ; one in the parietal region, where the frontal, occipital, and temporal nerves meet ; one over the temporo- maxillary joint ; a point upon the tongue for the lingual branch ; and one upon the integument of the chin, for the mental nerve. Painful points are often detected by pressure in the region of the spinous and transverse processes of the cervical verte- brae (the ''point apophysaire" of Trousseau). These puncta dolorosa are usually the starting points for the pain of the acute paroxysms, from which the pain radiates along the course of the nerves of the region affected. In some cases, these x^oints of tenderness may, however, be absent, when a central origin of the disease may reasonably be suspected. The relation of the filaments of the fifth nerve with certain vaso-motor fibers causes this type of disease to be often asso- ciated with certain disorders of secretion, since the vessels of the glands of the affected region are liable to dilate after an acute paroxysm cf pain. We can thus explain the abundant How of tears after an attack of neuralgia of the ophthalmic branch ; and of nasal mucus and saliva, when the second and third branches of the trigeminus are involved. Profuse sweat- ing of the region of the face affected is also sometimes weU marked both during and after the paroxysm. The vaso-motor communication may also explain why we have reported cases of local swelling, redness, elevation of the temperature, and, sometimes, erysipelatous inflammation of the affected region ; and why the hair has been observed to fall out, and the skin to become discolored and roughened. Hypertrophy of the cheek has been noticed, as a result of tic- douloureux, by Niemeyer, Brodie, Romberg, and Notta ; and ophthalmia has been produced by a similar condition confined to the first branch of the fifth ner\^e. When the nerve trunks, which at first were the seat of neuralgia, become destroyed or 164 THE CRANIAL NERVES. seriously impaired by pressure or granular degeneration, the face may undergo atrophy. Neuralgias of the fifth nerve, when due to cerebral tumors^ are often complicated by other symptoms which greatly assist in the diagnosis ; among the more prominent of which may be mentioned diplopia, vertigo, chronic cephalalgia, spasms of certain groups of muscles, paralysis of various types, and the absence of the puncta dolorosa, whose situations have already been mentioned. Tic-douloureux is not to be confounded with pain depend- ent upon the decay of teeth, inflammation of the temporo- maxillary articulation, tumors of the antrum, or extension of inflammation to that cavity from an acute attack of coryza, migraine, or the facial pains of lead poisoning, hysteria, or spinal affections. It is more common in women than in men : and most frequent between the ages of thirty and fifty. It i- more liable to occur in cold months than when the weather i warm (provided it be not due to actual disease) ; and it may follow traumatism, senile changes in the blood-vessels, and malarial poisoning. SPASM DUE TO THE TRIGEMINUS N^ERVE. The jaw may be rendered immovable, as in tetanus, by the masseter, temporal, and pterygoid muscles, all of which are supplied with motor power by the fifth nerve. The same form of spasm may be occasionally observed in attacks of hysteria. Clonic spasm of the temporal and masseter muscles, alter- nating with that of the depressors of the jaw (the mylo-hyoid and the anterior belly of the digastric), produces the chatter- ing of the teeth so often seen in the chill of inflammatory dis- eases and fevers and after exposure to cold. The pterygoid muscles, by a tonic contraction, may pro- duce the (grinding of the teeth ; a displacement of the jaw to one side, during an hysterical paroxysm, which lasted some days, is reported by Leube.* ■* As quoted by Rosenthal : " A Clinical Treatise of the Diseases of the Nervous Sys- tem" (Putzel's translation, New York, 1879). SPASM A^D PARALYSIS OF THE FIFTH NERVE. 165 Spasms of the muscles supplied by the trigeminus may be jj the result of apoplexy, cerebral softening, meningeal exuda- fi tion, lesions of the pons Varolii and medulla oblongata, hys- , teria, epilepsy, tetanus hysteria, hydrophobia, tumors irritat- Sinor the ganglion of Gasser, peripheral irritation, reflex causes dental pain, ulceration of the tongue or mouth, intestinal , ^. uterine irritation, teething, etc.), and rheumatism. 1 In rare cases, the depressors of the jaw may be the seat of ! localized spasm, in which event the mouth may be kept wide r open for a longer or shorter period. r! I PARALYSIS OF THE TRIGEMIKUS NEEVE. i ^ . I It IS a rare occurrence to observe a simultaneous paralysis of the motor and sensory roots of the trigeminus ; although [i anaesthesia of parts supplied by the branches derived from the sensory root may occur from central causes, and is per- haps more frequent than those symptoms dependent upon lesions involving the motor root. In lesions confined to the cerebral ganglia or cortex, however, the motor root is more often impaired than the sensory portion, while the sensory root, or some of its branches, is frequently affected from causes outside of the cranial cavity. In studying the condition of trigeminal anaesthesia, it must be prefaced that the regions affected, and therefore the results of the impaired nervous function, differ with the exciting cause, since a central lesion is liable to involve all of the sen- sory branches of the nerve ; while an external cause usually affects some individual branch. The central lesions of this disease comprise apoplectic clots ; destructive lesions producing ataxia ; hysteria ; local diseases or exudations which involve the large root of the fifth nerve between the pons Varolii and the ganglion of Gasser ; and lesions of the medulla oblongata, thus affecting its fibers of origin. The external causes include all forms of traumatism ; exposure to cold or heat ; surgical procedures ; caries or peri- ostitis of the bony canals ; suppuration of the soft tissues ad- 13 166 THE CRANIAL NERVES. joining the affected nerve ; local tumors and inflammatory exudations ; and certain blood conditions accompanied by nerve sclerosis (chiefly Norwegian leprosy).' The condition of facial anaesthesia may be complete, when sensibility to contact, pain, heat, or cold is abolished ; or par- tial, when extreme impressions can be perceived, and often differentiated as to the peculiar character of each. The needle points, the compass, and the electric brush are all employed in the examination of such a patient, in order to decide as to the extent, character, and degree of the existing pa- ralysis. If the opJithalmic nerve be the seat of anaesthesia, we may observe a contracted state of the pupil,'' insensibility of the mucous lining and integument of the upper eyelid, insensi- bility of the skin of the forehead and the external and in- ferior parts of the nose, and a total absence of the sense of contact in the anterior portions of the mucous membrane of the nostril. K the superior maxillary nerve alone be affected, the skin and mucous lining of the lower eyelid, the integument of the cheek, lower half of the nose, and the corresponding half of the upper lip, show an entire or partial abolition of sensibility ; while the mucous membranes of the middle and posterior por- tions of the nasal cavity, of the roof of the palate, and the en- tire soft palate and uvula, are similarly affected. The teeth and gums of the upper jaw will also be in the anaesthetic con- dition. If the inferior maxillary nerve be the seat of disease, with- out impairment of the motor root of the nerve, the integument of the outer surface of the ear, above the auditory canal,' of the temporal region, of the corresponding half of the lower lip, and in front of the temporo-maxillary articulation, will be destitute of sensibility. The mucous membrane of the corre- sponding side of the lower lip, tongue, cheek, tonsil, and gum of the lower jaw will be also anaesthetic, while the teeth of the ' See investif^ations of Daniellsen and Boeck, as quoted by Rosenthal, ' For effects of nerve influences on the pupil, see page 1 33 of this volume. ' For researches of Hilton on this point, sec page 158 of this volume. TROPHIC EFFECTS OF TRIGEMINAL PARALYSIS. 167 corresponding side of tlie lower jaw will likewise be deprived of sensibility. If you will recall the points which were made in reference to the effects of section of the trigeminus, you will be better able to understand why paralysis of any portion of this nerve should be followed by symptoms of late development, due, apparently, to some alteration in the nutrition and reactive power of the regions supplied by the nerve which is diseased. Tou will remember that the existence of certain unnamed fibers, called ''trophic fibers," was mentioned, whose close connection with the sympathetic nerve is highly probable, and whose function seems to be to control and regulate the blood supply of the regions to which they pass. Now, it is clinically observed that the paralysis of any of the three large branches of the trigeminus is followed by certain ulcer- ative and suppurative processes in the regions rendered anes- thetic, and that these effects are the most prominent and serious when the ophthalmic nerve is affected. Landmann and Bell were the first observers to point out that, in the human subject, purulent destruction of the eye was liable to follow pressure upon the trigeminus from tumors in the region of the ganglion of Gasser ; while Magendie (1824), Bock (1844), Snellen (1858), Spencer Watson (1874), Samuel (1860), and Meissner have done much to bring the results of defective nutrition, following impairment of nerve supply, to professional notice. It might add much to the interest of this volume to enter into the details of the inter- esting experiments and clinical observation, which have now become quite extensive regarding this subject, but it will ex- ceed the scope of this course to more than hastily sketch the results obtained. The opinion of Snellen, that the ulceration of the cornea and the suppurative conjunctivitis which fol- lows anaesthesia of the ophthalmic nerve were the mechanical effects of the irritation of dirt which the conjunctiva was no longer capable of perceiving, seems to have been confirmed by Watson ' and Baerwinkel," who found that an artificial cleans- ' "Med. Times," 1874. ^ "Arch. f. klin. Med.," 18Y4. 1G8 THE CRAXIAL NERVES. ing and closure of the eyelids caused recovery, without any effect upon the nerve condition. It was apparently also proven by Bock and Samuel that the condition of ansesthesia was not necessary to the development of these later processes, resulting in destruction of tissue, since the same results were observed when hypersesthesia existed. In reference to the course of the ''trophic fibers" of the ophthalmic nerve, the researches of Meissner and Schiif ' seem to locate their situation in the central portion of the nerve, since the other parts seem to preside over sensation only. Finally, the interesting experi- ments of Sinitzin," made in 1871, show some remarkable effects of the removal of the superior cervical ganglion of the sympathetic nerve upon trigeminal ophthalmia ; since it was often cured when once started, and prevented in every case where it was done before the trigeminus was divided. We know, irrespective of the theories of its causation, that the destruction of the sensory root of the fifth nerve is liable to be followed by destruction of sight, interference with the sense of smell, ulceration of the nose and gums, a tendency to inflammation and abscess of the soft tissues, and, possibly, to gangrene. It is of practical importance, however, to discriminate between that form of trigeminal anaesthesia dependent upon central lesions and that due to external pressure or disease. We may remember that the central form is usually con- fined to the inferior maxillary portion of the nerve ; that a previous history of cerebral disease wHl often be found ; that paresis or paralysis of the muscles of the face, tongue, jaws, or limbs will possibly coexist ; and that, if the lesion be a tumor at the base of the cerebrum, cephalalgia, neuralgias of special branches of the trigeminus, and a simultaneous affec- tion of some of the adjacent nerves of the cranium may be discovered. If the cause is outside of the cranium (provided it be not due to syphilis, rheumatic diathesis or traumatism), we may expect to find evidences of the previous existence of abscess, 1 " Centralbl.," 1807. « "Med. Centralbl.," 1871. DIAGNOSTIC VALUE OF THE FIFTH NERVE. 169 periostitis of some of the osseous canals through which the various branches of the trigeminus pass, or of local tumors which are creating pressure upon some nerve trunk or its terminal filaments. The motor root of the fifth nerve may he impaired from the pressure exerted by meningeal exudation, extravasations of blood, or tumors Avithin the cranium ; while it is frequently involved (after the sensory portion of the trigeminus) during the development of some type of basilar affection. The re- sults are manifested by a paralysis of the muscles of mastica- tion upon the side where the nerve is diseased, except the buccinator muscle, which derives its motor power from the facial nerve. The healthy muscles of the opposite side tend to crowd the lower jaw toward the affected side of the face during mastication, giving a peculiar expression during the act of eating. DIAGNOSTIC VALUE OF THE FIFTH KERVE. To what extent the distribution of the fifth nerve is of practical value in diagnosis may be estimated by the perusal of the lectures ' of Sir John Hilton upon the significance of pain and the use of rest as its cure. Cases have been reported by Paget, in his lectures on surgical pathology, and also by Anstie,'* where the hair of the entire scalp has turned white after a severe attack of neuralgic headache ; and another is reported by Anstie, where the hair of the eyebrow alone be- came perfectly blanched from pain in that region dependent upon the supra-orbital nerve. Hilton reports a case where the hair of the temple^ from the irritation excited in the dental branches of the fifth nerve through a decayed molar tooth, became suddenly gray (the temple being the region supplied by the auriculo-temporal branch of the same nerve) ; and an- other where an obstinate form of ulcer in the auditory canal, which was very painful, and had withstood all methods of treatment, was cured by the extraction of a decayed tooth in the upper jaw ; again illustrating the fact that irritation of ^ " Rest and Pain," London (Xew York, IS^Q). '^ " Lancet," 1866, 170 THE CRANIAL NERVES. one branch (the dental) can create disease at the seat of distri- bution of another branch of the same nerve (the auriculo- temporal). The temjporo-maxillary articulation has often been known to assume a condition of immobility during an attack of ear- ache, and to be immediately relieved by the application of an anodyne to the terminal filaments of the fifth nerve in the canal ; thus illustrating the effect of irritation of one branch (the auriculo-temporal) upon the others which supply the muscles of mastication, causing them to contract and thus fix the joint. Again, a furred condition of the lateral lialf of the tongue may almost be considered a pathognomonic sign of some source of irritation to the fifth nerve, which thus manifests itself in the peripheral distribution of one of its branches (the gustatory nerve).* Chronic ulceration of the cornea has also been reported by Anstie as a symptom produced by some source of irritation of the fifth nerve, far removed from the seat of disease. The intimate communication of the internal portions of the mouth with the eye, ear, and nose often accounts for many curious symptoms, which it would be difficult to account for, did we not know that pain may be felt at any branch of a nerve, when one of its trunks is irritated. I have, at the present time, a patient under my care, who is suffering from an obstinate ulceration of the tongue, and who had, previous to his consulting me, been treated for an inflammatory condi- tion of the ear, on account of a constant and severe pain, which was considered as separate and distinct from the trou- ble which was, at the same time, affecting his tongue. A sim- ple gargle of opium, which I ordered him to hold for fifteen minutes in his mouth at intervals, relieved the symptom in a very short time. A case is reported by Hilton where an enlarged cervical gland appeared with a simultaneous discharge from the au- ditory canal^ and where the explanation, by which a decayed ' Bransby Cooper ; John Hilton. DIAGNOSTIC VALUE OF THE FIFTH NERVE. lYi tooth was diagnosed as the cause of the condition, was as follows : The irritated dental branches of the fifth nerve caused an inflammation of the auditory canal, which is sup- plied by another branch (the auricular of the auriculo-tem- poral) ; this inflammation was followed by suppuration and excoriation of that canal, and, subsequently, by ab- sorption of the discharges by the lymphatic vessels, thus producing the enlarged gland of the neck. This expla- nation may seem a roundabout way of reaching a diagnosis, but the result of drawing the tooth proved, in this case, how well anatomy may guide us, if we only follow its teach- ings. Earache may not always be due to the fifth nerve, even when it is confined to the external portion of the organ, since the second cervical nerve supplies the lower and hacTc part of the external ear, so that pain in that region should lead us also to look for some cause of irritation to that nerve. The distribution of nerves to the scalp, as shown in the figure on page 159, renders the symptom of pain, in any por tion of the scalp, one which may guide us in looking for its cause ; since, if it is confined to the anterior and lateral aspects of the head, the fifth nerve is probably affected by some source of irritation (and a reference to the cut will tell you which branch of the nerve is distributed to the seat of pain), while, if confined to the posterior portion of the scalp, the occipital nerves are affected, and disease of the spine may be suspected, in the region of the first or second cervical ver- tebrae. The distribution of the fifth nerve to the conjunctiva, both of the globe of the eye and also of the lids, exhibits, to a wonderful degree, the axiom given you in the first lecture of the course, as to the harmony of action between the sensory nerves of the skin, the muscles adjacent, and the joints which they move ; since these parts stand very much in the same general relation to each other, if the movable point in the eyelids be taken as a joint, and the muscles of the lids as those which move it. 172 THE CRANIAL NERVES. An analogy has been drawn by a prominent author' between a common two-rooted spinal nerve and a great "compound nerve "of the head, whose sensory root corre- sponds to the sensory portion of the fifth nerve, and whose motor root comprises the third, fourth, fifth (its motor portion), sixth, and seventh cranial nerves, which, together, form the motor root of this compound nerve. Most of the reflex acts which are exhibited in the regions of the head and the upper portion of the neck can be explained by the free communication which exists between the sensory root of this ''compound nerve" and its different motor branches. It seems useless to further incorporate such cases, which go to prove that only by a thorough familiarity with anat- omy are we enabled to explain the many phenomena which often puzzle the practitioner ; and that, if we will but use it as a guide, diagnosis may be greatly simplified, and an easy remedy often discovered for the symptoms. SURGICAL ANATOMY OF THE FIFTH NERVE. Surgical operations are often demanded for the relief of those tormenting neuralgias which affect the branches of the fifth nerve. The simple division of a nerve is, at present, seldom prac- ticed, owing to the certainty of prompt reunion of the nerve divided. Resection of not less than two inches of its length is usually required to make reunion impossible, or very re- mote in point of time. It has been proposed to turn the pe- ripheral extremity of the nerve backward after section, or to interpose muscle or fascia, to prevent the possibility of union.'' Exposure and stretching of spinal nei-ves for the relief of neu- ralgia have been proposed by Yon Nussbaum, but are not usually practiced upon the cranial nerves. The supra-orhital nerve may be thus divided : Pass a narrow knife, subcutaneously, from a point two or three lines on the inner side of the supra-orhital notch, out- 1 John Hilton, " Kcst and Pain." » S. W. Mitchell. SURGICAL AXATOMY OF THE FIFTH NERVE. 173 ward, until the point has passed beyond the notch ; then turn the blade backward, and cut down to the bone. To resect the nerve, make a one-inch incision above and parallel to the supra-orbital arch ; seize the cut ends of the nerve in the wound, and remove it to the desired extent.' To excise the superior maxillary nerne^ a crucial incision is made over the infra-orhital foramen^ and, by the use of a small trephine, the anterior wall of the antrum is opened so as to include the foramen. The lower wall of the infra-orbital canal is now broken with a chisel as far as the spheno- maxillary fossa, and the nerve is then divided at the fora- men rotundum with a pair of scissors sharply curved. Meckel's ganglion is frequently removed with the excised nerve.' To divide the inferior dental nerve^ the incision may be made within the mouth or externally. If the trunk is to be removed, before the nerve enters the canal in the lower jaw, the external incision is made from the sigmoid notch to the edge of the jaw. The parotid gland is then turned backward, and the lower portion of the masseter muscle detached. A section of bone is now removed with a trephine, and the dental artery is tied, in case it be wounded ; the nerve may then be divided, and a half inch of it, which will be found to be exposed, resected. In the intra-huccal operation, the corner of the mouth is held wide open, and an incision one inch in length is made along the anterior part of the ramus of the jaw, through the fibers of the internal pterygoid muscle. This muscle is then loosened from the periosteum by the finger, where the nerve can be easily felt, at its entrance into the dental canal, and there divided. THE GANGLIA CONNECTED WITH THE FIFTH NERVE. In the cut which illustrates the distribution of the branches of the fifth nerve will be perceived four ganglionic enlarge- ^ J. X. Warren. - J. R- Wood. 174 THE CRANIAL NERVES. ments, exclusive of the ganglion of Gasser, which are con- nected with the nerve, and which have a most important function as regards the tissues to w^hich these branches are distributed. As you will notice, the first is connected with the ophthal- mic division, and is situated within the orbit. It is called the "ophthalmic ganglion," from its attachment; also the "len- ticular ganglion," from its shape ; and the " ciliary ganglion," since it gives off the ciliary nerves to the iris and the muscle of accommodation of vision. Like all the ganglia of the sym- pathetic nerve, it has a motor root^ a sensory root^ and a sym- patJietic root^ and it furnishes 'branches of distribution to neighboring parts. The second is called "Meckel's ganglion," after its discov- erer; and the " spheno-palatine ganglion," since it is chiefly distributed to the region of the palate. It is situated in the spheno-maxillary fossa, and sends branches to the orbit, nose, hard and soft palate. It lies in close relation with the superior maxillary nerve. The third is called the "otic ganglion." It lies upon the inferior maxillary nerve below the foramen ovale, and sends branches to the two tensor muscles, viz., the tensor tympani and the tensor palati. It is thus physiologically associated with the acts of hearing and deglutition. The fourth is called the " submaxillary ganglion," since it lies above the submaxillary gland. It is by means of the dis- tribution of the chorda tympani nerve to this ganglion that some physiologists attempt to explain the apparent effect which that nerve has upon the sense of taste in the anterior two thirds of the tongue.' The following table ' will perhaps assist you in remember- ing the special points of each of these ganglia, as it shows the various sources of supply to each, as well as branches of dis- tribution : ^ See previous portion of this chapter, where the gustatory nerve is discussed. * After Keen. THE ABDUGEN8, OR SIXTH NERVE. THE GANGLIA OF THE FIFTH CKANIAL NERVE. 175 Name. Situation. Sensory root. Motor root. Sympathetic root. Branches of distribution. 1 OPHTHAL- MIC or CILIAKY. Between the optic nerve and e'xt. rectus. 5th nerve— Nasal bri»nch. 3d nerve. Cavernous plexus. To ciliary muscle and iris. MECKEL8 SPHENO- PALATINE. Spheno- inaaillary jossa. 5th nerve— Spheno-pala- iine branches. Tth nerve, through Vidi- an and large petrosal branches. Carotid PLEXUS, by means of Vi- dian nerve. Orbital, nasal, naso-pala- t^ne, anterior or largo palatine, iiiiddle or ex- ternal palatine. Post, or I Levator palati, small •< Azygos uvulaB, palatine f Palato-glossus. ^ OTIC. Below the J or amen ovale. OTH NERVE— Auriculo- temporal branch. 7th nerve, through f^mall petrosal. 5th nerve. through i7it. pterygoid branch. Plexus on the MIDD1,E ME- NINGEAL ARTERY. To tensor tympani and tensor palati muscles. SUBMAXIL- LARY. Above the suhmadcil- lary gland. StH NERVE— Lingual or gustatory branch. 7Tn nerve, through chor- da tympani branch. Plexus on the FACIAL ARTERY. To submaxillary gland and mucous membrane of the mouth. By reference to the above table, you will perceive that the ]ensory root of each of the four ganglia is derived from the yth cranial nerve by means of some of its branches ; that bhe motor root is derived, in three cases out of four, from the "ieventli cranial nerve ; and, finally, that in every case is the sympathetic root derived from 2i plexus upon some neighbor- ig blood-vessel. 'HE ABDUCENS, OR SIXTH NERVE (MOTOR OCULI EXTERNUS). The apparent origin of this nerve is from a groove between bhe anterior pyramid of the medulla oblongata and the pos- terior border of the pons Varolii. The nerve may be said to )ossess two roots, one of which can be traced into the pyra- midal body of the medulla, and the other into the pons Ya- 'olii itself. This latter root is sometimes wanting. Its deep origin has been traced by Lockhart Clarke to a [nucleus in the gray matter of the fourth ventricle of the brain, on the outer side of the locus cceruleus. This nerve is purely motor in its function, and is distribu- ted to the external rectus muscle of the eye. 176 THE CRANIAL NERVES. The most careful researches of Vulpian have as yet failed to discover any decussation of the deep fibers of this nerve, and there would seem to be a physiological explanation for the absence of such an arrange- ment, since the two external recti muscles are seldom called into simultaneous action,' and the normal movements of the eyes are opposed to such a po- sition as would ensue if they should act in common. The sixth nerve anasto- moses with the sympathetic nerve in the cavernous sinus, where it receives filaments from both the carotid plexus and from Meckel's ganglion ; and a few sensory filaments are said to be given to it from the oph- thalmic branch of the fifth cranial nerve in this locality. Occasionally, this nerve sends a filament to the ophthalmic ganglion, and thus to the iris, and it is claimed by Longet that this arrangement (which is an exceptional one) exists in those cases of paralysis of the motor oculi nerve in which there is no apparent effect produced upon the mobility of the pupil. This nerve has no practical importance to the diagnostician, save the one fact that, in case it be paralyzed, the eye will present the condition of internal strabismus ; that the ap- parent size of the objects perceived by the retina is magni- fied,^ and that the head will be so deflected as to avoid the perception of double images.' Tlie explanation of both of these effects, as the result of ' After the eyes have been drawn inward, as in attempts to foeus near objects, these muscles help to restore the axes of vision to a state of parallehsm. 2 For explanation of this symptom, the reader is referred to page 143 of this volume. 3 See page 140 of this volume. Fig. 59. — Distribution of the motor oculi externtts. (Ilirschfeld.) 1, trunk of the motor oculi communis, with its branches (2, 3, 4, 5, 6, 7) ; 8, motor oculi externtts, passing to the external rectus muscle ; 9, filaments of the motor oculi externus anastomosing icith the sympathetic ; 10, ciliary nerves. THE FACIAL, OR SEVENTH NERVE, 177 paresis of certain ocular muscles, has already been given in the previous lecture upon the third cranial nerve, and need not be again repeated. It should not be forgotten, however, that internal strabismus is not always due to paralysis of the external rectus muscle, but may indicate a condition of con- genital or acquired hyperopia, causing a weakness of the ex- ternal rectus muscle. THE FACIAL, OR SEVENTH NERVE. This nerve has its apparent origin from a groove between the olivary and restiform 'bodies of the medulla oblongata, and, like the three preceding, has its deep origin in a gray nucleus in the floor of the fourth ventricle, in the upper half of that space near to the postero-median fissure. ' The fila- ments of origin, within the substance of the medulla oblongata, may be traced as a fan-like expansion upon the floor of the fourth ventricle, some of which terminate in the gray nucleus, above described, of the same side as that on which the nerve escapes, while other fibers may be seen to decussate^ thus passing to the nucleus of the opposite side. No filaments have as yet been satisfactorily traced upward beyond the limits of the medulla." This nerve accompanies the nerve of hearing throughout the whole length of the internal auditory canal^ and there communicates with it by a few filaments. It then enters a curved canal within the temporal bone, called the aqueduct of Fallojpius^ where it gives off the three petro- sal nerves and the chorda tympani branch, whose physiologi- cal action has been already considered in connection wdth the fifth nerve. From this canal, it escapes through the stylo- mastoid foramen,, having, before its exit, given a tympanic ^ Lockhart Clarke. An accessory portion of this nerve — the " nerve of Wrisherg " — conveys fibers to it, whose deep origin may be traced to the lateral column of the cord. Its importance is now being extensively discussed, as having a connection with the chorda tympani nerve. 2 The deep origin of the fibers of the facial nerve seems to have some connection with the upper portions of the enccphalon (as shown by the clinical facts mentioned in previ- ous pages, when discussing " crossed paralysis ") ; but little is, as yet, positively known concerning the course and termination of these fibers. * 178 THE CRANIAL NERVES. branch to the ear.' In the region of the stylo-mastoid fora- men, it communicates with five nerves^ namely, the great auricular (a branch of the cervical plexus), the auriculo-tem- FiG. 60. — Superjicial branches of the facial and the fifth. (Hirschfeld.) 1, trunk of tlie facial ; 2, posterior auricular nerve ; 3, branch lohich it receives from the cervical plexus / 4, occipital branch ; 5, 6, branches to the mvscles of the ear ; 7, diyas- iric branches ; 8, branch to the stylo-hyoid mutcle ; 9, superior terminal branch ; 10, temporal branches ; W, frontal branches ; 12, branches to the 07'bicHlaris palpebrarum ; 13, nasal, or snboi'bital brandies ; 14, buccal branches ; 15, inferior terminal branch ; 16, mental branches; 11, cervical branches; 18, superficial temporal nerve (branch of the fifth); 19, 20, frontal nerves (branches of the fifth); 21, 22, 23, 24, 25, 26, 27, branches of the fifth ; 28, 29, 30, 31, 32, branches of the cervical nerves. poral (a branch of the fifth nerve), the pneumogastric, tlie glosso-pharyngeal, and the carotid plexus of the sympathetic ; and, subsequently, it divides and is distributed to the muscles. The facial is the great motor nerve of the muscles of the ' Occasionally also the f lament of communication to the pneumogastric nerve. DISTRIBUTION OF FACIAL NERVE. 179 face; lience the nerve of expression.' It supplies, in addi- tion to the facial muscles, the muscles of the external ear ; Fig. 61. — A diagram of the branches of the facial nerve. 1, main trunk of nerve in internal auditory canal ; 2, branches of communication with AUDITORY nerve; 3, orificc of aqueduct of Fallopixis ; 'i, large petrosal nerve; 5, small petrosal nerve ; 6, external petrosal nerve ; Y, filaments to the laxator tympani muscles ; 8, chorda ii/mpa?ii nerve ; 9, stylo-mastoid foramen ; IQ^postcrior auricular nerve ; 11, filament supplying the stylo hjoid and digastric muscles ; 12, the temporo- FACiAL division of the nerve ; 13, the temporal branches ; 14, the malar branches ; 15, the infra-orbital branches; 16, the buccal branches; 17, the snpra-maxillary branches; 18, the infra-maxillary branches; 19, the cervico-facial division; 20, " intumescentia ganglioformis '" — the seat of origin of the petrosal nerves. three muscles of the neck, namely, the stylo-hyoid, posterior belly of the digastric, and the platysma ; one muscle of the middle ear, the stapedius ; and one muscle of the palate, the levator palati." By means of the chorda tympani branch, it controls the secretion of the parotid and submaxillary glands, and, possibly, the sense of taste.' By the large pe- ' Sir Charles Bell. '^ Schiff, 1851 ; Bernard. Possibly also some other muscles, by means of the lingual branch, described by Hirschberg. 3 Sappcy ; Ilirschfeld ; A. Flint, Jr. ; J. C. Dalton. The fibers of the chorda tympani nerve, by some of the later authorities, are said to arise from an intermediate nerve formed by a branch from both the seventh and eighth cranial nerves, and called the "portio intermedia" or "nerve of Wrisberg." 180 THE CRANIAL NERVES. trosal branch, the levator palati and azygos uviilse are sup- plied ; and, by the small petrosal branch, the tensor tym- pani and tensor palati muscles are furnished with motor power. Several interesting articles have lately appeared upon the subject.' It is claimed by Vulpian that the facial nerv^e also con- tains vaso-motor fibers^ which are distributed to the vessels of the tongue and side of the face. The effects of paralysis of the facial nerve were first brought to professional notice by Sir Charles Bell, who di- vided it for facial neuralgia, and the characteristic deformity which resulted is still known under the name of "Bell's pa- ralysis." In this condition, the affected side loses its normal expression, and becomes abnormally smooth on account of the obliteration of the normal lines and wrinkles, due to the action of the antagonistic muscles on the healthy side." The patient loses all power of closing the eye of the affected side even in sleep, since the orbicularis palpebrarum muscle is paralyzed ; the mouth is no longer symmetrical, since it is drawn toward the healthy side ; the saliva is with difficulty retained ; and the act of whistling becomes an impossibility, as the lips can not be systematically governed. This condi- tion may be produced by exposure to severe cold, as in sleigh- riding ; by abscess or tumors of the parotid region, as the result of the pressure created ; by diseases of the ear or inju- ries to the temporal bone, which impede the free action of the nerve ; and by cranial lesions. It is particularly impor- tant that the surgeon should familiarize himself, not only with the situation and course of the main trunk of this nerve, but also with the course of its branches, previous to performing operations about the face, or in the vicinity of the mastoid process, and in the upper portions of the neck. 1 Vulpian, "Lancet," 1878; II. R. Bigelow, *' Brain," 1876; E. C. Spitzka "Medical Record," 18 SO. * Hence the aptness of the remark by Romberg, as quoted by Hammond, that " there is no better cosmetic for elderly ladies than facial paralysis." DISTRIBUTION OF FACIAL NERVE. 181 The distribution of this nerve to the muscles of the palate and to the stylo-hyoid explains the impairment of deglutition when the facial nerve is paralyzed ; while the filament to the stapedius muscle may create modifications in the sense of hearing under similar conditions. ' Fig. 62. — BcWs paralysis. (Modified from Corfe.) The following tabulated arrangement of the branches of the seventh nerve "" will possibly prove of service to you as an aid to memory during your student life ; and, as a guide for reference or review in your professional labors, such tables are always of value : ' The tensor tympani muscle may also be involved. 2 Copied from " The Essentials of Anatomy" : Darling and Ranney, New York, 1880. 14 182 TEE CRAmAL NERVES. TABLE OF THE BRANCHES OF THE FACIAL I?^ERVE. Branches of communication. Branches of distribution. '' In the auditory canal. \ In the aqueduct of Fallopius. ■< At its exit from the stylo-mas- toid foramen^ with the fol- lowing nerves : l^ On the face. I In the aqueduct of Fallopius. Near the stylo-mastoid fora- men. On the face. Branch to auditory nerve. Large petrosal (to Meckel's ganglion). Small petrosal (to otic gangl'n). External petrosal (to meningeal plexus). Tympanic branch. ^ Great auricular. Auriculo-temporal. ^ Pneumogastric' I Glosso-pharyngeal. (^ Carotid plexus. Branches to fifth cranial nerve j Tympanic nerve. \ Chorda tympani nerve. C Posterior auricular nerve. J Diagastric branch. 1 Stylo-hyoid branch. [ Lingual branch.^ j Temporo-facial nerve. i Cervico-facial nerve. If you will look at this diagrammatic drawing (Fig. 63), you will perceive how simple is the arrangement of the branches of communication between the facial nerve and the fifth cranial nerve and its ganglia. While the drawing is intended to be purely schematic, still it also illustrates some of the anatomical points pertaining to the course and forma- tion of the Vidian nerve, as well as the relations of the clior- da tympani nerve to the membrana tympani^ as it passes through the middle ear to reach the canal of Huguier. There is a practical point pertaining to the deep origin of the fibers of the facial nerve, which may often be of value in determining the seat of pathological lesions within the sub- stance of the brain. In hemiplegia, especially in that variety which is due to haemorrhage, the face is sometimes affected upon the same side as the body and sometimes upon the oppo- site side, thus being impaired, respectively, either upon the side opposite to the cerebral lesion or upon the same side as the lesion. To explain these phenomena theoretically, we * This communicating filament is given off in the aqueduct of Fallopius as often as at the stylo-mastoid foramen. ^ Described by Ilirschberg. Supplies the stylo-glossus and palato-glossus muscles and the tongue. CROSSED FACIAL PARALYSIS, 183 must suppose that the facial nerve fibers are affected by the lesion within the brain before they decussate (following them from within outward), in case the face is paralyzed on the same side as the lesion ; and that the decussating fibers are Fi~. 63. — A diaf/ram to show tlie relations between the facial nerve and some portions of the fifth nei've. A, Gasscrian ganglion; B, ophthalmic nerve; C, superior maxillary nerve; D, inferior maxillary nerve (sensory portion) ; E, inferior maxillary nerve (motor portion) ; M, Meckel's ganglion; \^ facial nerve, entering the aqveduct of Fallopius ; 2, inlumcs- centia ganglioformis (an enlargement on the nerve) ; 3, facial nerve, following the curve of the aqueduct of Fallopius ; 4, facial nerve, escaping from stylo-mastoid fora- men ; 5, large petrosal branch, joining caiotid filament 11 to form the Vidian nerve, and entering the Vidian canal ; 6, stn all petrosal branch, going to " otic ranglion " 10 ; 7, chorda tympani nerve, escaping from the canal of Huguier after winding over the upper border of drum membrane of ear, 9 ; 8, gustatory nerve, joining with the chorda tympani nerve; 9, extamal drum membrane of the ear; 10, otic ganglion ; 11, f la- ment from carotid plexus to form the Vidian nerve ; 1 2, the iter chordoe posterius, ad- mitting the chorda tympani nerve into the cavity of the middle ear. pressed upon or destroyed by the lesion, in case the face be affected on the same side as the body. I^ow, it has been observed as a pathological fact, that when a lesion involves parts of the encephalon anterior to the pons Varolii, the phenomena dependent upon paralysis of the facial nerve are perceived on the same side as the hemiplegia ; while, if the lesion be situated either in the lower part ' of the pons Varolii or below it, the face is paralyzed on the same side as the lesion, or on the side opposite to the hemiplegia. ' Gubler has shown that the facial nerve is not paralyzed upon the same side as the lesion, if the injury to the pons Varolii be anterior to the imaginary line drawn through the points of escape of the trigemini. 184 THE CRANIAL NERVES. For this reason, the occurrence of hemiplegia, with crossed facial paralysis ' has been received as a most positive indica- tion of a lesion situated upon the same side of the brain as that of the face, and either within the substance of the pons Varolii or in parts of the encephalon posterior to it. Such clinical facts as these seem positively to indicate that some of the deep fibers of the facial nerve pass upward into the cere- brum^ and that the decussation of the filaments of origin within the floor of the fourth ventricle is of little physiological importance compared to these other fibers ; but, unfortunate- ly, no anatomical investigations have, so far, discovered fibers of this nerve which could ba clearly demonstrated as passing upward beyond the pons Yarolii. It has been often noticed by different observers that, in case the facial nerve was paralyzed, the uvula and soft palate were affected and drawn toward the healthy side by the an- tagonistic muscles, whose motor power remained unimpaired. Later investigation has shown, however, that this affection of the palate only occurs in those cases of paralysis due to im- pairment of the facial nerve within the aqueduct of Fallopius, or from some cranial lesion which affects its filaments of origin.'' The experiments of Bernard seem to demonstrate that the facial nerve^ and not the glosso-pharyngeal alone, is con- nected with movements of the xelum palati, but not with the movements of the pillars of the fauces. The construction of the small petrosal branch, however, being composed partly of fibers derived from the glosso-pharyngeal nerve, may still justify a doubt upon this point. Hirschfeld describes a small filament, which the facial nerve gives off soon after it emerges from the stylo-mastoid foramen, ''the lingual branch^'"' which is distributed to the tongue and to the stylo-glossus and palato-glossus muscles. ' A term used to cover those terms of paralysis where the face is paralyzed on the side opposite to the side of the body affected. See diagram on page 60. * The petrosal nerves, which carry the motor fibers to these muscles, must be impaired to cause any deflection of the palate. ^ See tabic on page 182. COMMUNICATIONS OF FACIAL NERVE. 185 This may possibly exi3lain the observation of Bernard : that paralysis of the facial nerve, after section, produces a devia- tion of the tip of the tongue; and the same effect has been, at fifferent times, recorded as the result of paralysis of the facial erve from intra-cranial causes. BKAXCHES OF C0MMUKICATI0:N" OF THE FACIAL J^TEKVE. Some of the branches of communication which are given uff by the facial nerve, to join with other nerves, or to be dis- tributed to ganglia, are of physiological importance. Thus the levator palati and the azygos uvuIcb muscles derive their motor power from the large petrosal branch after it enters Meckel's ganglion;' while the palato-glossus and palato- pJiaryiigeus muscles probably derived their motor power Fig. 64. — Chorda tympani nerve. (Hirschfeld.) 1, 2, 3, 4, facial nerve passing thrcupjh the aqueductus Fallopii ; 5, ganglioform enlarge- ment ; 6, great petrosal nerve ; 7, spheno-palatine ganglion ; 8, small petrosal nerve ; 9, chorda tympani ; 10, 11, 12, 13, various branches of the facial ; 14, 14, 15, glosso- pharyngeal nerve. from the communicating filament between the facial and the glosso-pharyngeal nerves, as shown by Longet. This distribu- tion explains, in part, why more or less difficulty is perceived in degliitUlon after division or paralysis of the facial nerve, and still more clearly why the pronunciation of certain words becomes impaired, and the expulsion of mucus from the back ^ Gray, Quain, Sappey, and others. 186 THE CRANIAL NERVES, portion of the mouth and from the pharynx is an act of extreme difficulty. The communication of the cervical plexus with the poste- rior auricular branch of the facial affords sensory filaments to the parts over the muscles which that nerve supplies. The filament of communication between the facial and the auditory nerves enables the muscle of the middle ear supplied by the facial ' to act in harmony with the acoustic apparatus ; while the communication between the fifth nerve and the facial enables the latter to follow that general axiom ^ of nerve distribution by which the skin over the insertion of Fig. 65. — A diagram to shoio the course of the large and small petrosal nerves and the Vidian nei'ves. A, otic ganglion ; B, Meckel's ganprlion ; C, petrous portion of the temporal bone ; D, pe- trotts portion of the temporal bone (its apex corresponding to the carotid canal at the base of the skull) ; E, petrous portion of the temporal bone (its base correspond- ing to the external auditory meatus) ; F, petrous portion of the temporal bone (its superior border, separating the middle and posterior fossae of the skull); 1, the facial nerve entering the petrous portion of the temporal bone by means of the " me- atus auditorius internum ^^ ; 2, the facial nerve following the curve of the ''aqueduct of Fallopius"; 3, i\\c facial nerve escaping from the temporal bone by means of the " stylo-mastoid foramen" ; 4, the large petrosal nerve, escaping into the cavity of the cranium by means of the " hiatus Fallopii " ; 5, the small petrosal nerve, escaping into the cavity of the cranium by a foramen of its own ; 6, the '■'■ foramen basis cranii," affording passage for the largo petrosal nerve out of the cranium ; 7, the " foramen ovale," affording passage for the small petrosal nerve out of the cranium, and thus to the otic ganglion ; 8, a filament from the carotid plexus of the sympathetic nerve, joining the large petrosal nerve to form the Vidian nerve ; 9, the Vidian canal, trans- mitting the Vidian nerve to MeckcVs ganglion, B; 10, the Vidian nerve. muscles is supplied by the same nerve as the muscles them- selves. The communication between the facial nerve and the ' The stapedius. ^ mnon, *' Rest and Pain." See also page 12 of this volume. COMMUNICATIONS OF FACIAL NERVE. 187 pneumogastric might at first seem, to tlie casual reader, one of accident, rather than of design, on the part of the Creator ; but, when we consider how intimately the respiratory func- tions and the movements of the face are associated with each other, the design at once becomes evident. Paralysis of the muscles which dilate the nostrils has been shown to have a marked effect upon respiration through the nostril ; and, in the horse, which can only breathe through the nose, the effect of division of both of the facial nerves is to produce death from suffocation, . since the nostrils collapse. It was this synchronism between the movements of the nostrils and the respiratory act that first led Sir Charles Bell ' to regard the facial nerve as the one which presided over the function of respiration, and is still often called one of the "respiratory nerves of Bell^ A case is reported by this famous investigator where a patient, afflicted with unilateral facial paralysis, was obliged to lie upon the sound side, and to hold the paralyzed nostril open with the fingers, in order to breathe with comfort'' The distribution of the facial nerve to the muscles of the nose creates an impairment of the sense of smell^^ when that nerve is injured, since the free entrance of air is interfered with. The act of sniffing^ which requires for its complete performance a dilated nostril, is rendered almost if not quite impossible, and thus a contact of odoriferous substances with the mucous membrane of the upper nasal chambers is me- chanically interfered with, and acute jDerception of smell em- barrassed. BRANCHES OF DISTRIBUTIOJT OF THE FACIAL KERVE. The motor branches of the facial to the muscles of the ear are of more importance in animals than in man, since the ear in the animal becomes capable of perceiving sound with acute- ness only by a change in its relative position to the head. The stylo-hyoid and the posterior helly of the digastric muscles exhibit again the influence of the facial nerve upon ^ " Lectures on the Nerves." ^ Qp^ cit. ^ A. Flint, Jr., op, cit. 188 THE CHAXIAL JSFERVES. the act of deglutition ; and the same remark will apply to the stylo-glossus muscle. When the facial nerve has passed through the parotid gland, the two branches distributed to the face, viz., the tem- poro-faclal and the cervico-facial^ become not only motor in their function, but are also supplied with sensory filaments from their communication with other nerves ; so that some of their terminal filaments are distributed to the integument of the face, as well as those derived from the fifth cranial nerve^ which would not be the case were the nerve not so supplied with sensory nerve fibers. The filament of the facial nerve which supplies the platys- ma muscle affords a beautiful example of the fact that the nervous supply of the general muscular system, if carefully studied, constantly teaches us points of great physiological value as to the function of individual muscles, since, in the expression of melancJioly,^ and in the typical countenance of thoracic and abdominal diseases," the platysma muscle plays a most important part, and is therefore supplied by the nerve of expression. Again, the muscles of the region of the mouth are impor- tant agents in the prehension of food (especially so in animals, who often can not eat when the lips are paralyzed), and should properly be, in some way, connected with the muscles of mas- tication (chiefly supplied by the fifth nerve), and those of deglutition (supplied by the facial and the glosso-pharyngeal nerves) ; hence, the facial nerve is afforded communicating- branches with both t^Q fifth and the glosso-pharyngeal nerves. One of the muscles of the face, the buccinator^ which is supplied exclusively by the facial nerve, plays a most impor- tant part in mastication as well as in expression ; hence, when the facial nerve is paralyzed, the cheek can no longer force the food between the teeth, and a tendency toward accumula- tion of food within the cheek of the affected side becomes so * Carpenter, op. cit. ' Sir Charles Bell, " Anatomy of Expression." See, also, article by the author, " The Human Face ; its Modifications in Health and Disease, etc.," " New York Med. Jour.," September, 1880. I I PHYSIOLOGY OF THE FACIAL NERVE. 189 distressing to the patient that the fingers are frequently em- ployed, during attempts at mastication of the bolus, to force the food between the jaws by pressure upon the external por- tion of the face.' The value of this muscle in expression is made manifest in those acts where the cheek is either inflated with air, or where it is drawn inward, thus indicating the states of emacia- tion or extreme hunger. Much of the success of a comedian often depends ui^on the control which he possesses over the buccinator muscle. When t^Qfaxiial nerve upon both sides is paralyzed, mastication is almost as much impaired (on account of the buccinator muscles) as if the inferior maxillary nerve was destroyed. The flaccidity of the buccinator muscle in "Bellas paraly- sis " accounts for the peculiar puffing movement of the cheek which accompanies each act of expiration , giving to the face an appearance similar to that noticed when puffing of a pipe is attempted ; while, in those rare cases where the facial nerve is paralyzed upon both sides, the face assumes a condition which is remarkable for the entire absence of expression, and which can only be compared to the effect of covering it with a mask. Many of the muscles of the face are of value as guides in diagnosis^ since, in certain types of disease, some parts of the face are more affected than others.' This subject, how- ever, is too complicated to be hastily reviewed, and it has suffi- cient value to merit its special consideration. It may be perceived, by reference to the diagrammatic rep- resentation of the branches of the facial nerve, that the tem- poro-facial branch animates all of the muscles of the upper part of the face, while the cervico-facial branch supplies the lower region of the face and portions of the neck." This ex- plains why, after the temporo-facial branch has been divided, ^ A. Flint, Jr., op. cit. 2 See article by the author on *' The Human Face ; its Modifications in Health and Disease, and its Value as a Guide in Diagnosis : " "New York Med. Jour.," December, 1880. ^ Sec page HQ of this volume. 190 THE CRANIAL NERVES. as has occurred in operations upon the cheek, the eye stands wide open even during sleep ; the lower lid becomes everted from traction of the parts below, and also from the effect of gravity ; the occipito-frontalis and corrugator supercilii can no longer make either transverse or perpendicular wrinkles upon the forehead ; and the upper portion of the face is ab- normally smooth and passive, while the lower portion pre- serves all its normal power of movement. Should the eervico-facial branch become alone impaired, the power of prehension of food by the lips is arrested, the action of the buccinator in mastication is s'topped, and that process is proportionately interfered with ; the digastric and stylo-Jiyoid muscles are, however, not paralyzed, since the special branches to those muscles are given off above the ori- gin of this branch, and thus deglutition is not embarrassed. CLIN^ICAL POIISTTS AFFORDED BY THE FACIAL NERVE. The diseases which affect the facial nerve may produce the different varieties of facial spasm and paralysis ; the former being the result of some lesion which creates simply irritation, while the latter indicates some existing pressure or degeneration, which impedes the free action of the nerve. SPASM OP THE MUSCLES OF THE FACE. In a class of cases, by no means infrequent, facial spasm is perceived, to a greater or less degree, as the result of some cause of irritation to the nerve filaments of the trunk of the facial nerve, or to some of its branches. These mimic spasms, or '' convulsive tic," are dependent upon an hereditary ten- dency, in some mstances ; since reported cases exist where the second generation, and even the third, has manifested the symptoms of facial spasm. We also meet this condition as an ■ accompaniment of epilepsy, eclampsia, hysteria, tetanus, and chorea ; again, in certain mental diseases, where the brain or its investing membranes are affected ; and, finally, we see it developed under extraordinary periods of excitement. Cases are on record where simple exposure, wounds of the BELL'S PARALYSIS. 191 face, and pressure upon the peripheral filaments of the facial nerve have resulted in facial spasm. Perhaps this condition is most frequently met with as an evidence of some reflex act, excited through some other cranial nerves ; hence we find it associated with such causes of irritation as caries of the teeth, periostitis, inflammatory affections of the eyeball, lids, or con- junctiva. Remak reports a case where a diseased condition of the brachial plexus caused spasms to start in the hand and progress along the side of the neck to the face, again illus- trating the reflex character of the disease. It is such cases as these latter that often test the ana- tomical knowledge of the diagnostician, since a command of the various anastomoses of nerves often enables the skilled anatomist to detect the seat of irritation far from the apparent seat of disease, and thus to obviate a distressing condition by some simple medicinal or surgical remedy. The spasms of the facial muscles may assume either the tonic or clonic character. ' The former variety is observed in such conditions as tetanus, the late rigidity of paralyzed mus- cles, and the irritation following upon severe exposure and too intense faradization ; while the latter are the most com- mon, and result in those convulsive twitchings of the forehead, eyes, eyelids, nose, mouth, cheeks, and tongue, which pro- duce the most extreme and often ludicrous distortion of the features. I have known such clonic spasms of the face to be produced by the irritation of worms in the intestine in children, and, in one case, to follow uterine disease in an adult. A peculiarity of these spasms is, that certain muscles seem to contract in a regular sequence or rhythm, and that, although the contraction may be prolonged and severe, no fatigue is usually complained of by the patient. PARALYSIS OF THE MUSCLES OF THE FACE. The general appearance of a sufferer from a well-marked attack of ''Bell's paralysis" has already been depicted in a cut,' and described in the preceding text, under the effects ^ Sec page 181 of this volume. 192 THE CRANIAL NERVES. of section of the facial nerve ; but many points of practical value pertain to this condition which have not as yet been mentioned, and which help greatly in making a diagnosis as to the exciting cause and the seat of the existing lesion. The symptoms produced by any impairment to the free action of the facial nerve vary to a marked extent with the degree of the paralysis, and the individual branches which may be in- volved ; and distinctions between the various forms of facial paralysis, met with in a large clinical field, have been devel- oped, by the investigations of Romberg, from those general propositions first advanced by Bell. In studying the types of facial paralysis, we may start with advantage by reviewing the different groups which are clinically recognized. These may be enumerated as the intra- cranial ; the auditory (where the existing lesion is confined to the interior parts of the temporal bone) ; the rlieumatic ; the traumatic ; Wv^ syphilitic ; and, finally, the dipTitJieritic form. We may also have the paralysis confined to one side of the face, the unilateral^ or, affecting both sides of the face, the bilateral^ or facial diplegia. In the intra-cranial form of facial paralysis, the lesion of the brain is usually confined either to the base, or to the pons Varolii. If the pons Varolii is affected, the facial nerve will not be alone involved, as a rule, but a partial or complete hemiplegia will usually exist, which will be on the same side of the body as the facial paralysis, provided the upper (an- terior) half of the pons is the seat of disease, but on the side opposite to the facial paralysis (crossed paralysis'), if the lower (posterior) part of the poiis is affected. There is, per- haps, no point in the anatomy of the encephalon which is of more certain value to the diagnostician than the fact, first pointed out by Gubler, that a line drawn transversely across the pons Varolii at the points of escape of the trigemini marked the spot of probable decussation of fibers of the facial nerve ; so that, if a lesion be anterior to this line, the facial ^ For definition of this term and the various types met witb, see page 59 of this volume. CAUSES OF BELL'S PARALYSIS. I93 paralysis will correspond to the hemiplegia, but, if behind that line, the condition of ''crossed paralysis" of the facial and body type will be produced. A point of some diagnostic value in the detection of intra-cranial lesions, by means of the facial nerve, is afforded by the degree of the facial paraly- sis, since it is usually complete if caused by lesions of the pons Varolii or by the pressure of tumors of the base of the cerebrum. The second form of facial paralysis, viz., that dependent upon some abnormal condition within the temporal hone, is liable to follow suppuration or haemorrhage within the aqueduct of Fallopius ; scrofulous caries of the temporal bone ; local degeneration of the nerve within the aqueduct of Fallopius ; local pressure upon the nerve from tumors, etc.; and traumatisms of all kinds, of sufficient intensity to injure the deeper parts or to directly involve the nerve itself. If you will recall the anatomy of the facial nerve within the aqueduct of Fallopius, and the branches which are given off in that canal, you will be better able to appreciate the points afforded by this anatomical knowledge in the diag- nosis of the seat of a lesion which is causing facial paraly- sis. We have already, in connection with the effects of section of the facial nerve, mentioned the facial deformity which ensues ; and the same description will answer for the effects of disease of the nerve, or pressure upon it, after it has escaped from the stylo-mastoid foramen. But the symp- toms to which I now propose to call your attention are not included in that description, since they are due to branches which are given off by the facial nerve before it escapes from the temporal bone ; although the same facial deformity, and all the evidences of impairment of the nerve on the distal side of the stylo-mastoid foramen, will, of necessity, be also present. If the lesion be situated above the point of origin of the chorda tympani, but on the distal side of the petrosal nerves, the sense of taste wiU probably be affected on the correspond- 194 THE CRANIAL NERVES. ing side of the anterior two thirds of the tongue ; ' but the sense of taste is not, as a rule, abolished, although it is greatly diminished in acuteness. How this nerve affects the sense of taste, and the various experiments which have been recorded concerning it, will be found by reference to preced- ing pages." If the lesion of the facial nerve be situated behind the ganglionic enlargement from which the three petrosal nerves arise, the patient will reveal a depression of the arch of the palate upon the affected side ; thus, it will be seen to hang lower than the healthy side, and to approach a straight line along its free edge, rather than that of a marked curve, as in health. This is due to the paralysis of the levator palati muscle, which is supplied with motor power from Meckel's ganglion, through the large petrosal nerve. In addition to this deformity, the soft palate is drawn toward the unaffected side by the tensor tympani muscle, since the same muscle of the paralyzed side is no longer capable of acting, as it is supplied by the small petrosal nerve. The distribution of the small petrosal nerve to the otic ganglion still further explains why, in this type of cases, the secretion of the parotid gland of the affected side is diminished ; while the intimate asso- ciation of the chorda tympani nerve with the submaxillary gland accounts for deficient secretion from that source. It has been observed that the sense of hearing becomes ex- cessively acute^ when the facial nerve is affected on the proxi- mal side of the point of origin of the petrosal nerves. This may possibly be due to the paralysis of the tensor tympani muscle, as suggested by Landouzy, since that muscle is sup- plied with motor power by a filament derived from the otic ganglion ; although the investigations of Brown- Sequard seem to point to a vaso-motor spasm of the internal ear, resulting in a condition of hypersesth^sia of the acoustic nerve. The third form of facial paralysis occurs in connection ^ The reader is referred to those pages in which the gustatory branch of the fifth nerve is discussed, since authorities differ as to the value and interpretation of this symp- tom. ' See page 160 of this voUimo. CAUSES OF BELVS PARALYSIS I95 with tlie rheumatic diathesis. It is well known that the in- fluence of cold, which is particularly liable to favor rheu- matic manifestations, is more keenly felt in the region of the cheek and eyelids, as showTi by Weber ; and the experiments of Wachsmuth,' upon the effect of cold upon the vaso-motor fibers in the region of the stylo-mastoid foramen, also point to the retardation, or, possibly, the entire suppression, of the blood supply to the facial nerve, as the explanation of this type of paralysis. A mild form of periostitis in the bony canals, through w^hich the different branches of the facial nerve pass, may also occur in the rheumatic type as an excit- ing cause. The traumatic types of facial paralysis may involve the entire nerve or only individual branches. Its symptoms, therefore, somewhat depend upon the situation and extent of the injury. It has been known to follow severe contusions of the face, cheek, or neck, incisions made by the surgeon, saber cuts and gunshot wounds, the compression exerted by the forceps during delivery, the pressure of growing tumors, sup- puration within the parotid gland or lymphatics of that region, and the pressure caused by extensive or deep cica- trices. This type of paralysis is often extremely obstinate and of long duration, and may be permanent ; since the nerve may have undergone changes in its structure or the muscles may have become impaired. In syphilis, facial paralysis is sometimes developed. It may thus indicate the formation of intra-cranial tumors or meningeal exudations, which either press upon the nerve trunk or interfere with its fibers of origin. It may also be an evidence of extra-cranial lesions, such as periostitis of the mastoid region, tumors of the facial or cranial bones, or sup- puration dependent upon caries or necrosis of the temporal bone (if the entire nerve be affected), or of some of the facial bones, if individual branches only show evidences of pressure. Cases are on record where the symptoms of facial paraly- sis have followed an attack of diphtheria. This is but one of 1 As quoted by Rosenthal. 196 THE CRANIAL NERVES. the various forms of paralysis which are frequently observed as sequelae of this peculiar blood poison. It may be well to hastily review the principal complica- tions which are most frequently observed in connection with facial paralysis. These have a special importance to the sci- entific practitioner in enabling him to diagnose, not only the condition of the patient, but also the seat of the existing lesion. We have considered the effects of lesions within the aque- duct of Fallopius. These may create (in addition to those of the facial muscles) symptoms referable to the impairment of the chorda tympani nerve (see page 193), of the petrosal nerves (see page 194), acoustic manifestations, or an effect upon the salivary secretions. Intra-cranial lesions usually cause destruction of the mo- tor power of the entire nerve, and, therefore, of all of its branches ; hence, we are liable to have all of the previous symptoms present, as well as those of facial deformity. Special branches of the nerve may be individually para- lyzed, and thus produce symptoms referable only to those parts in which the motor power is deficient. The anatomy of the separate branches, as shown in the cuts on previous pages, will help you to understand the special symptoms which an impairment of any one branch would produce. The condition of Mlateral facial paralysis, or '-'facial dijplegia^^^ is a rare form of disease. It implies some form of pressure or degeneration, which shall affect the nerve of each side simultaneously ; hence it may accompany a lesion situ- ated in the anterior half of the pons, which crosses the median line ; an exostosis of the interior surface of the. basilar process of the occipital bone ; an intra-cranial aneurism ; and the pres- ence of excessive meningeal exudation at the base of the brain. It sometimes accompanies the condition of labio-glosso-pha- ryngeal paralysis (Duchenne's disease), provided the lesion ex- tends so as to involve the nuclei of origin of the facial nerves ; and is occasionally met with in the course of certain chronic cerebral diseases. Jaccoud claims that the spontaneous atro- CAUSES OF FACIAL DIPLEGIA. I97 phy of both facial nerves can occur without an exciting cause of a local character being detected ; and the same opinion is maintained by Pierreson/ who found a hyperplasia of the connective tissue of the nerve and the development of amy- loid corpuscles to constitute the pathological changes. I This type of paralysis may be due to peripheral causes, such as exposure to intense cold, as in sleigh-riding, rheu- matic inflammation of the nerves, and diseases of the petrous portion of the temporal bones (necrosis, caries, syphilitic Otitis, suppurative inflammation of the middle ear, etc.). The experiments of Schiff upon animals in whom both facial nerves had been divided, and the investigations of Trous- seau, Wachsmuth," and Davaine, have helped to clear up the effects of this double lesion, and to render its diagnosis from Duchenne's disease more positive than our previous knowl- edge would permit. In the human race, this condition is characterized by the following symptoms : a fixed and im- movable countenance, a peculiar droopiQg of the angles of the mouth, a collapsed appearance of the nostrils during inspira- tion, a sinking inward of the cheeks during the inspiratory effort, and a protrusion or inflation of the cheek when the air is expired. The tone of the voice becomes of the most dis- tinctly nasal quality, and the patient, from the inability to pronounce the labial consonants, is almost unable to make the simplest sentences intelligible. In consequence of paralysis of the buccinator muscles, which are supplied by the facial nerves, the act of mastication becomes embarrassed, and de- glutition is greatly interfered with ; hence it is not uncom- mon to see such patients use the finger to push the food into the grasp of the isthmus of the fauces, so as to swallow the bolus. When the head is inclined forward, the saliva runs from the mouth, in spite of all efforts to prevent it. The con- dition of the eyes,' which remain wide open on account of the ' As quoted by Rosenthal. ^ As quoted by Hammond. ^ In both the unilateral and bilateral forms of facial paralysis, the patient often can avoid the irritation of dirt and the intense light by closing the eyelids with the pressure of the finger, or by a strip of adhesive plaster. 15 198 THE CRANIAL NERVES, paralysis of the orbicularis palpebrarum muscles, affords a most important point in the discrimination between this dis- ease and the paralysis of Duchenne. So marked is this de- formity that the patient can not wink, and thus the tears are not distributed over the globe of the eye, to wash off any dust which may enter ; while, on account of the paralysis of the tensor tarsi muscle, the tears are not drawn into the lachry- mal sac, and therefore tend to flow over the cheek and create scalding. THE AUDITORY, OR EIGHTH NERVE. This nerve is strictly one of special sense^ namely, that of hearing. It arises from a gray nucleus in the floor of the fourth ventricle (where its fibers form the so-called '^linese Fig. 66. — A diagram of the auditory nerve and its branches. 1, audiiori/ nerve, entering the meatus auditorius internus ; 2, communicating filaments to the facial nerve, given off in the internal auditory canal ; 3, filaments given off to supply the cochlea ; 4, filaments given off to supply the posterior semicircular canal ; 5, filaments given off to supply the saccule ; 6, filaments given off to supply the utri- cle ; 7, filaments given off to supply the external semicircrdar canal ; 8, filaments given off to supply the ampullce of the superior semicircular canal. transversse " which decussate in the median line), and also, in part, from the restiform body of the medulla oblongata. It is claimed by Foville ttiat its fibers may be also traced to the flocculus and the gray matter of the cerebellum, and, from recent statements of Lockhart Clarke, additional fibers may be traced from the auditory nucleus, which pass directly through the restiform body of the meduUa. The course of the nerve, as far as the orifice of the internal THE AUDITORY, OR EIGHTH NERVE. 199 auditory canal, lies parallel with tliat of the facial nerve, since the same arachnoid sheath invests them both, but, before that canal is reached, a filament is given off from both these nerves to form an intermediate nerve, called the "pars intermedia," or the ''nerve of Wrisberg." This intermediate portion is now supposed to be the chief source of origin of the chorda tympani nerve^ and thus to be connected with the special sense of taste. Fig. 6*7. — Distribution of the cochlear nerve in the spiral lamina of the cochlea {the cochlea is from the right side and is seen from its antero-inferior part). (Sappey.) 1, trunk of the cochlear nerve ; 2, 2, 2, membranous zone of the spiral lamina ; 3, 3, 3, terminal expansion of the cochlear nerve, exposed in its whole extent by the removal of the superior plate of the lamina spiralis ; 4, orifice of communication of the scala tympani with the scala vestibuli. The color of the auditory nerve filaments is grayish. The filaments differ from those of the other cerebro-spinal nerves (excepting those of special sense) in having a softer consist- ence. Some of the later researches seem to show that the filaments of this nerve are destitute of the "white substance of Schwann," and thus resemble those of the olfactory nerve, while the axis cylinders are of very large size as compared with those of other nerves. It is also claimed that small, nu- cleated, ganglionic enlargements can be demonstrated along the course of these fibers of the trunk of the nerve, but the minute anatomy of the auditory nerve is yet a subject for further investigation. Within the internal auditory canal, the eighth nerve 200 THE CRAmAL NERVES. divides into two branches, the anterior of which supplies the cochlea, while the posterior branch is distributed to the semi- circular canals and to the saccule and vestibule. These two main branches are given off close to the meatus auditorius intemus. At the bottom of the internal auditory canal, the three subdivisions of the vestibular nerve pass through small open- FiG. 68. — General view of tlie organ of hearing. (Sappey.) 1, pinna ; 2, cavity of the concha, on the walls of which are seen the orifices of a great number of sebaceous glands ; 5, external auditory meatus ; 4, angular pro- jection formed by the union of the anterior portion of the concha with the posterior wall of the auditory canal ; 5, openings of the ceruminous glands, the most internal of which form a curved line, which corresponds with the beginning of the osseous portion of the external meatus ; 6, membrana tympani and the elastic fibrous mem- brane which forms its border ; 7, anterior portion of the incus ; 8, malleus ; 9, han- dle of the malleus applied to the internal surface of the membrana tympani, which it draws inward toward the projection of the promontory ; 10, tensor tympani muscle, the tendon of which is reflected at a right angle to become attached to the superior portion of the handle of the malleus; 11, tympanic cavity ; 12, Eustachian tube, the internal or pharyngeal extremity of which has been removed by a section perpen- dicular to its curve; 13, superior semicircular canal ; 14, posterior semicircular ca- nal; 16, external semicircular canal ; 16, cochlea ; 17, internal auditory canal ; 18, facial nerve ; 19, large petrosal branch, given off from the panglioform enlargement of the facial and passing below the cochlea to go to its distribution ; 20, vestibular branch of the auditory nerve ; 21, cochlear branch of the auditory nerve. ings in a cul-de-sac situated at that point, and are distributed to the utricle, the saccule, and the three ampullae. The cochlear nerve, which is the other main branch of the auditory, enters the base of the modiolus^ and its filaments DISTRIBUTION OF AUDITORY NERVE. 201 subsequently escape from the central canal of the modiolus through minute canals^ which enable them to reach their point of distribution in the internal portion of the cochlea. The terminal filaments of this nerve are now believed to be connected with the spindle-shaped cells of the organ of CortL It is impossible, within the compass of this lecture, to en- ter into the minute anatomy of the ear with sufficient detail to enable you to properly appreciate the mechanism by which the waves of sounds, produced from without, are transmitted to the membrana tympani, and subsequently to the cochlea, where they are perceived by the auditory nerve filaments. To properly appreciate the difficulties which arise in determining the exact method by which the human ear is enabled to de- termine not only the intensity of the sound perceived, but also its pitchy quality^ and musical properties^ not only would the anatomy have to be given in detail, but many of the laws of physics discussed. The following general state- ments, however, may assist you in studying this complicated subject, and afford an explanation of some of those symp- toms of disease which are referred to the ear. The diagram shown you on the blackboard ' is designed to assist you to grasp some of the principal points in the ana- tomical construction of the ear, which are necessary for the clear comprehension of the physiology of audition. It can be perceived that the external auditory canal and its accessory portion which we call the ear or auricle (which is placed on the exterior of the skull for the purpose of deflecting the waves of sound into that canal) lie external to the membrana tympani ; and, for that reason, all of these parts, viz., the cartilages of the pinna, its ligaments, the bony canal leading to the membrana tympani, and its cutaneous lining, are in- cluded under the general term " the external ear^'' in contrast to the chambers which lie deeply within the temporal bone, called the middle ear, or ^Hhe cavity of the tympanum,'' and the internal ear, or the "labyrinth.''' The middle ear, or " tympanum," lies between the mem- ' See diagram further on in the chapter. 202 THE GRANIAL NERVES. brana tympani and the internal ear, or "labyrintli," and is contained within the petrous portion of the temporal bone. It communicates with the pharynx^ by means of the Eusta- Fio. 69. — A diagram to illvMraie the mechanism of the act of hearing. A, the auditorg canal (the arrow showing the waves of sound entering) ; B, the cavity of the middle ear, or " tympanum ") ; C, the utricle, communicating with the semicircu- lar canals ; D, the saccule, communicating with the scala vestihdi of the cavity of the cochlea ; E, the Eustachian tube, allowing of the entrance of air into the middle ear from the pharynx; 1, the memhrana tympani, which first receives the vibrations of the waves of sound ; 2, the chain of bones, which transmit these vibrations to the mem- brane covering the fenestra ovalis (annular ligament of the stapes) ; 3, the membrane, covering ihe fenestra ovalis (annular ligament of the stapes) ; 4, the foramen rotun- dum, where the waves of sound return to the cavity of the middle ear and are lost (membrana tympani secundaria) ; 5, the ampullae of the semicircular canals ; 6, the semicircular canals ; 7, the " scala vestibtdi " of the cochlea ; 8, the cupola, at the apex of the cochlea, where the scala vestibuli and the scala tympani of the cochlea join each other; 9, the " scala tympani,''^ leading downward from the cupola of the cochlea to the foramen rotundum ; 10, irUemal auditory canal, where the auditory nerve enters. chian tube, and is thus enabled to afford free access to the air of the external world, and insure the same density of at- mosphere on both sides of the membrana tympani. It is this anatomical arrangement that causes gunners to hold the mouth wide open when exploding large pieces of ordnance, to avoid a rupture of the membrana tympani, since the waves of sound can thus enter the Eustachian tube at the same time that they pass down the external auditory canal, and the membrana tympani should, theoretically, be made to stand TEE MIDDLE EAR. 203 motionless, if the EustacMan tube were wide open, since the waves of sound upon each side of the membrane would neu- tralize each other/ In the cavity of the middle ear, a cTiain of small hones is so arranged as to afford a source of trans- mission of the impulses of sound from the membrana tym- pani to the fenestra ovalis,' which is closed by the stapes' Fig. 70. — Ossicles of the tympanum of the right side, magnified 4 diameters. (Arnold.) A, malleus ; 1, its head ; 2, the handle ; 3, long, or slender process ; 4, short process ; B, incus ; 1, its body ; 2, the long process with the orbicular process ; 3, short, or pos- terior process ; 4, articular surface receiving the head of the malleus ; C, stapes ; 1, head ; 2, posterior crus ; 3, anterior crus ; 4, base ; C* base of the stapes ; D, the three bones in their natural connection as seen from the outside ; a, malleus ; 6, incus ; c, stapes. and its annular ligament. This chain of bones is suspend- ed by a ligament attached to the roof of the middle ear, and the separate bones are connected together by joints* lined with synovial membranes, so that the slightest movement is readily carried from one to the other. Muscles are also at- tached to these bones, for the object of bringing the mem- ' Valsalva's method, " which consists of making a powerful expiration, with the mouth and nostrils closed," is also used if the ear be stopped with cotton at the same time. 2 A doctrine first suggested in 1851 by Edward Weber, and subsequently verified by experiments in 1868 by Politzer. ^ One of the small bones of the middle ear. * Helmholtz first described the exact nature of the joint between the malleus and the incus. He compared it to " a joint used in certain watch-keys, where the handle can not be turned in one direction without carrying the steel shell with it, while in the other direc- tion it meets with only a slight resistance." This device assists to convert the bones into a state of resistance, resembling that of a solid piece of bone, when muscular action locks this joint firmly. 204 THE CRANIAL NERVES. brana tympani and the bones themselves into the best possi- ble condition for the accurate appreciation of sound im- pulses.' The cavity of the middle ear is in communication with the cells in the mastoid portion of the temporal bone, and some additional effect may be thus produced upon the vibrations of the air within the middle ear.' Fig. 71. — TJie left bony labyrinth of a neio-born child, foytoard and outward view. Modi- fied from a photograph. (Riidinger.) 1, the wide canal, the beginning of the spiral canal of the cochlea ; 2, the fenestra ro- tunda ; 3, the second turn of the cochlea ; 4, the final half turn of the cochlea ; 5, the border of the bony wall of the vestibule, situated between the cochlea and the semicircular canals ; 6, the superior, or sagittal semicircular canal ; 7, the portion of the superior semicircular canal bent outward ; 8, the posterior, or transverse semicircular canal ; 9, the portion of the posterior connected with the superior serai- circular canal ; 10, point of Junction of the superior and the posterior semicircular canal; 11, the ampulla ossea externa; 12, the horizontal, or external semicircular canal. The internal ear, or '' labyrinth,^ ^ lies within the petrous portion of the temporal bone, and internal to the tympanum. It consists of a series of chambers, hollowed out within the bone, called the vestibule^ the cochlea^ and the semicircular ' The tensor tympani muscle, on account of a peculiar arrangement of the joint be- tween the malleus and the incus, renders all the articulations firm, tightens the little liga- tures, and presses the stapes against the fenestra ovalis, thus bringing it in contact with the fluids of the vestibule. Sec foot-note on page 203. ^ For the surgical application of this arrangement, see article on the bones of the head, by the author, " New York Medical Record," October 16, 1880. THE INTERNAL EAR. 205 canals, within each of which a membranous tube is sus- pended between two liquids, one within the tube, the "en- dolymph," and one between the tube and the bony walls, the ' ' perilymph. " This membranous portion is called the ' ' mem- Fig. 72. — Diagram, of the lahyrinth^ vestibule^ and semicircular canals. From a photo- graphy and somewhat reduced. (Riidinger.) Upper figure: 1, utricle; 2, saccule; 3, 5, membranous cochlea; 4, canalis reuniens; 6, semicircular canals. Lower figure: 1, utricle; 2, saccule ; 3, 4, 6, ampullae; 5, 7, 8, 9, semicircular canals; 10, auditory nerve (partly diagrammatic); 11, 12, 13, 14, 15, distribution of the branches of the nerve to the vestibule and the semicircular canals ; 16, ganglioform enlargement. hranous labyrinth^'^^ and is an exact reproduction of the bony labyrinth, except that it is smaller in point of size, so as to admit the presence of fluid between it and the bone. It serves as a support for the terminal filaments of the auditory nerve, which, by being suspended between two fluids, are en- 206 THE CRANIAL NERVES. abled not only to perceive tlie slightest vibrations of the fluids/ but are also thus protected from the possibility of in- jury, which would be great were they placed in contact with the bone. The membranous labyrinth which fills the cavity of the vestibule is divided into two portions, called the saccule and the utricle; the former of which communicates directly with the cochlea, while the latter communicates with the semicircular canals, as can be seen in the diagram. The cochlea is essentially that part of the internal ear which is enabled to appreciate most of the important elements of sound, viz., its note and quality ^ It consists of an exca- FiG. 73. — A transverse section of the spiral canal of the cochlea {diagrammatic).^ S. v., the scala vestihuli ; S. M., the scala media ; S. T., the scala tympani ; 1, mem- brane of Reissner ; 2, " organ of Corli^'' covered by the " memhrana iectoria,''^ or " membrane of Corti " / 3, membrana basilaris ; 4, ligamentum spiralis^ extending the whole length of the spiral canal of the cochlea ; 5, upper layer of the lamina spiralis ossea ; 6, lower layer of the lamina spiralis ossea ; 7, a nerve filament es- caping from the central canal of the modiolus^ and going to the organ of Corti ; 8, a ganglion attached to the nerve filament, called the " ganglion spirale." vation in the temporal bone which resembles, in its construc- tion, the shell of a snail, having a central pillar, the Tnodio- lus, which runs from its base to its apex, and a spiral canal^ ' It is a well-recognized law of physics that the fluids transmit vibrations in every direction with equal force, and, therefore, no better medium could possibly be had for the auditory nerve filaments to be in contact with. ^ Complete destruction of the cochlea probably causes total deafness, while destruction of the semicircular canals does not seem to have any marked effect upon the ability to appreciate sound. • * From the " Essentials of Anatomy " (Darling and Ranney), New York, 1880. I C0N8TEUGTI0N OF THE COCHLEA. 207 running around this central portion for two and a half com- plete turns. The spiral canal of the cochlea is divided into three portions called the scala mstihuU, scala tympani, and the scala medial The first communicates, at its lower part Fig. 74. — Vertical section of the organ of Corti of the dog, magnified 800 diameters. (Waldeyer.) a-6, homogeneous layer of the basilar membrane ; v, tympanic layer, with nuclei, granu- lar cell protoplasm, and connective tissue ; ai, tympanic lip of the crista spiralis ; c, thickened portion of the basilar membrane ; d, spiral vessel ; e, blood-vessel ; /, h, bundle of nerves ; g, epithelium ; i, inner hair cell, with its basilar process, Jc ; /, head-plate of the inner pillar ; m, union of the two pillars ; «, base of the inner pillar ; o, base of the outer pillar ; /), ^, r, outer hair cells, with traces of the cilia ; t, bases of two other hair cells ; z, Hensen's prop cell ; l-h, lamina reticularis ; w, nerve fiber passing to the first hair cell, p. with the vestibule ; hence its name ; the second terminates in the middle ear, and hence its name ; while the third is, in ^ The experiments of Laborde (Des fonctions du limagon, " Trib. Med.," Septembre 12, 1880) to determine the function of the cochlea were made upon the Guinea-pig, an animal in whom the organ is particularly accessible. The following facts were considered by him as -fully proven : 1, Destruction of the cochlea had no effect in the production of vertigo or disturbances of coordination ; 2, destruction of the cochlea produced complete deafness, which, however, did not appear until several days after the operation. He concludes, from these facts : 1, That the auditory nerve contains both motor and sensory fibers, the former being distributed to the semicircular canals, the latter to the saccule, utricle, and cochlea ; 2, that the cochlea is not the only organ for the appreciation of sound, since the utricle and saccule participate, to some unknown extent, in that func- tion ; 3, that the deafness which occurs after excision of the cochlea alone is probably due to an extension of inflammation to the utricle and saccule, or to the formation of a rigid cicatrix, which prevents the transmission of an auditory impulse to those parts. While these facts need subsequent confirmation (since the experiments are by no means conclusive), they are worthy of due consideration in the discussion of this complicated and imperfectly understood organ. 208 TEE CRANIAL NERVES. reality, but a space partitioned off from the scala vestibuli for the protection of the true organ of hearing, "the organ of Corti." The preceding diagram (Fig. 73) will help to make this plain to you. This figure represents, in a diagrammatic way, the appear- ance of a longitudinal section of the spiral cord in the cochlea, in any portion of its two and a half turns around the modio- lus. It will be perceived at a glance that the canal is divided into an upper {s. v.) and a lower {s. t.) portion, partly by bone (5 and 6) and partly by membrane (3). It will also be readily seen that a portion of the scala vestibuli is divided off by the membrane of Reissner^ and that thus a separate cavity is formed throughout the whole length of the spiral canal, called the ''scala media." Within this last-named cavity will be noticed a body covered with hair-like processes, "the organ of Corti^^'' which rests upon the membrane forming the floor of the scala media, and called for that reason the ''basilar Fig. 75. — TJie two pillars of the organ of Corti. (Sappey.) A, external pillar of the organ of Corti : 1, body, or middle portion ; 2, posterior extrem- ity, or base ; 3, cell on its internal side ; 4, anterior extremity ; 5, convex surface by which it is joined to the internal pillar ; 6, prolongation of this extremity. B, internal pillar of the organ of Corti : 1, laody, or middle portion; 2, posterior extrem- ity ; 3, cell on its external side ; 4, anterior extremity ; 5, concave surface by which it is joined to the external pillar ; 6, prolongation, lying above the corresponding prolongation of the external pillar. C, the two pillars of the organ of Corti, united by their anterior extremity, and forming an arcade, the concavity of which, looks outward : 1, 1, body, or middle portion of the pillars ; 2, 2, posterior extremities ; 3, 3, cells attached to the posterior extrem- ities ; 4, 4, anterior extremities joined together ; 5, terminal prolongation of this extremity. membrane.''^ There is, furthermore, shown in this figure the means by which the terminal filaments of the cochlear nerve (one of the branches of the auditory nerve) escape from the central canal of the modiolus and reach the scala media. THE ORGAN OF CORTL Such a figure will greatly assist you to properly appreciate the discussion of the function of each of these various parts, and also enable you to grasp the principal points in the physiology of the act of hearing, which are to be con- sidered. The organ of Corti may be compared to a harp, since its rods are of dijfferent lengths. It is a continuous structure for the entire course of the spiral canal of the cochlea. Helm- holtz has advanced the theory ' that the several thousand strings of this organ admit of the appreciation of all varieties of musical tone, since each note or chord creates a vibration Fig. 76, — Distribution of the cochlear nerve in the spiral lamina of the cochlea {the cochlea is from tJie right side and is seen from its antero-inferior part). (Sappey.) 1, trunk of the cochlear nerve; 2, 2, 2, membranous zone of the spiral lamina; 3, 3, 3, terminal expansion of the cochlear nerve, exposed in its whole extent by the removal of the superior plate of the lamina spiralis ; 4, orifice of communication of the scala tympani with the scala vestibuli. in those strings only which are necessary to reproduce it, in the same way as a piano, when a note is sounded, will create a vibration in the same string of an adjoining instrument. Hensen, however, claims that the basilar membrane is com- posed of elastic fibers of varying lengths^'' and that these separate fibers are thrown into vibration by sounds carried to the cochlea, which, in turn, transmit their vibration to the ' This theory is opposed by the facts that the rods of Corti are not elastic, and they are absent in birds, who can unquestionably perceive sound. - By some authors this theory is attributed to Helmholtz. 210 THE CRANIAL NERVES. organ of Corti lying upon them, and thus inform the auditory- nerve filaments of the effect of each individual sound/ In the act of hearing, the vibrations produced within the membrana tympani by the waves of sound are transmitted across the cavity of the middle ear, to a membrane covering an opening nearly opposite the external drum, called the fenestra ovalis^ by means of a chain of small bones within the cavity of the middle ear, and, by means of secondary vibrations thus produced within this latter membrane, the impulse is transmitted to the fluids of the mstibule. The vibrations now travel along the fluids of the scala vestibuli of the cochlea and of the semicircular canals, thus passing in two different . directions. In the semicircular canals, accord- ing to some observers, the direction from which the sound springs is perceived,' while the vibrations carried along the scala media ' in the cochlea are transmitted to the fila- ments of the auditory nerve in the " organ of Corti," proba- bly by means of vibrations of the membrana hasilaris, thus affording the appreciation of the note and the quality of the sound perceived. After reaching the apex of the coch- lea, the vibrations are transmitted from the scala vestibuli downward along the course of the scala tympani till they reach the ''membrana tympani secundaria," which covers ihe fenestra rotunda^^ whQTQ they are lost,* being no longer ^ The membrana tedoria, or " membrane of Corti," probably acts as a damper, to arrest the vibrations excited within the scala media, as its situation suggests no other pos- sible function. ' The function of the semicircular canals is yet a matter of doubt, and is now receiv- ing the attention of experimental physiologists. They are supposed by some authors to relieve excessive pressure within the labyrinth when the stapes is driven too forcibly in- ward ; and, by others, to secrete the fluid of the labyrinth ; while by some they are consid- ered to be the external organs of coordination of muscular movement. •3 The saccule communicates with the scala media by means of a small canal (shown in Fig. 72), called the " canalis reuniens." * An opening in the inner wall of the cavity of the middle ear. ^ According to some authorities, the vibrations in the membrana tympani secundaria are created, simultaneously with those at the fenestra ovalis, by the vibrations of the air in the middle ear created by the movements of the external drum membrane, and an impulse thus travels simultaneously along the scala tympani and the scala vestibuli, both goiwj in the same direction, to meet each other at the cupola. They consider the second drum, at the foramen rotundum, as a proof of this function, but it must be apparent to any one that all the openings of the labyrinth into the middle ear must be closed in some way PHYSIOLOGY OF AUDITION. 211 transmitted, on account of the absence of any conducting medium. The free entrance of air to the cavity of the tympanum, or the middle ear, affords an equal density of air upon either side of the membrana tympanic and thus insures a vibration of that membrane in absolute unison with the vibrations of the sound which it is called upon to record, as the waves pass down the external auditory canal. The function of the organ of Cort% of the membrana hasi- laris^ or of the otoliths^ can not be stated with any degree of certainty, since new discoveries are constantly being made, although some theories of their functions have been already given. The minute construction of the scala media and its con- tained organs can be found by reference to more extensive treatises. CLINICAL POIN^TS OF INTEREST DEPEN^DEN^T UPON THE AUDITORY NERVE. In attacks of auditory vertigo, or Meniere's disease, there is much more than ordinary giddiness. The patient will often to prevent the escape of the perilymph. While it is difficult to positively decide this point, I am personally inclined to regard the foramen rotundum as the seat of termination of wave sounds, rather than a means of transmim.on of impulses to the fluids of the cochlea. Dr. A. H. Buck, in a late treatise on the " Diagnosis and Treatment of Ear Diseases," again advocates theories long maintained by him as to the physiology of audition, which may be thus given : The impulse of the stapes, at the fenestra ovalis, is carried by means of the perilymph directly into the scala vestibuli. This causes compression of the fluid in the scala media, which, in turn, causes pressure upon and movement of the elastic " mem- brana basilaris." The pressure is thus transmitted, for a second time, to the fluid in the scala tympani, and, as fluids are incompressible, the membrana tympani secundaria, which closes the foramen rotundum, is forced into the cavity of the middle ear until the force is expended, when it returns to its normal condition. It will be thus perceived that he discards the saccule and the canalis reuniens as a channel for the passage of the acoustic wave. He also questions the existence of any communication, at the cupola, between the scala vestibuli and the scala tympani. While his theory seems ingenious, and perhaps more in accordance with fact than the older views, and is well illustrated by diagrams and supported by some carefully conducted experiments, still it can not, as yet, be said to be positively confirmed. His view as to the absurdity of the membrana tympani se- cundaria being a transmitter of sound waves to the cochlea agrees with my own, as advo- cated above. He seems also to favor the theory that the basilar membrane is the true vibrating medium, which carries to the auditory nerve the appreciation of the note sounded, rather than the " organ of Corti." 212 THE CRANIAL NERVES. tell you that, when the attack commenced, everything began to whirl, or possibly appeared to be moving toward one side ; that his gait became unsteady, and, if walking was possible, that he reeled and staggered ; while, in some severe cases, the patient feels unsafe even when lying upon a bed or sofa, and may be obliged to grasp the sides of the couch to protect him- FiG. 77. — Right memhrana tympanic seen from within. From a photography and somewhat reduced. (Riidinger.) 1, head of the malleus, divided ; 2, neck of the malleus ; 3, handle of the malleus, with the tendon of the tensor tyrapani muscle ; 4, divided tendon of the tensor tympani ; 6, 6, portion of the malleus between the layers of the membrana tympani ; 7, outer (radiating) and inner (circular) fibers of the membrana tympani ; 8, fibrous ring of the membrana tympani; 9, 14, 15, dentated fibers, discovered by Gruber; 10, poste- rior pocket; 11, connection of the posterior pocket with the malleus; 12, anterior pocket; 13, chorda tympani nerve. self from a sensation of falling. In many cases, these symp- toms are markedly intensified by movement of the liead^ and, in some instances, such movements often tend to bring about an attack.' The patient is usually pale and haggard, some- ' Buzzard, "Lancet," March 4, 1876. MEmERE'S DISEASE. 213 times perspires freely, and often vomits/ while ^am within the head is a symptom which not infrequently accompanies such an attack. The extent to which this type of vertigo may be manifested varies from an attack of but momentary duration, where the patient can retain his feet, to those severe forms of the disease where the attack is accompanied by a loss of consciousness, which may remain for some hours, and resemble the condition of epileptic vertigo. There seems to be little doubt that, in these cases, the at- tack is always preceded or followed by some abnormal con- dition of the ear, and that this diseased condition was the starting point of the vertigo." Sometimes the patient has long been deaf in one ear, or a condition of deafness may follow the first attack of vertigo ; again, the approach of an attack of vertigo may be told by the occurrence of noises within the ear of one side, while, in some cases, there exists a constant noise within the ear, which increases as the attack of vertigo is imminent. It is often extremely difficult to persuade a patient, suffer- ing from this affection, that the attack is not dependent upon a disordered state of the digestive apparatus, and especially is this the case when the ear trouble is of old standing, or when the patient is unconscious of any defect in his hearing, which is by no means an unusual occurrence. Such patients are better satisfied if the attack be attributed to the liver, dys- pepsia, or nervousness. I quote the following sentence from Hughlings- Jackson ^ as evidence that this difficulty is met with even among the most enlightened of the community. He says : " Even medical men, who have aural disease, often totally reject the proffered explanation of their attacks of vertigo ; many of them ascribe their ailment to digestive ^ Ferrier, " Vomiting in connection with cerebral disease," " Brain," July, 1870. ^ The occurrence of vertigo and interference with coordination is not alone produced by local disease of the ear, even when associated with impairment of hearing. It may indicate disease of the cerebellum or of the medulla oblongata, which creates irritation of or some interference with the auditory nucleus. For the clinical facts pertaining to this symptom, the reader is referred to pages 63 and 64 of this volume. 3 Hughlings-Jackson, "Lancet," March 11, 1876 ; same author, "Lancet," March 11, 1876; Gowers, "Lancet," March, October, 1880. 16 214 THE CRANIAL NERVES. troubles. A medical man had deafness in his left ear, with, occasional slight vertigo. One day, while walking in his gar- Fio. 78. — Section of the first turn of the spiral canal of a cat newli^-born. — Section of the. cochlea of a human foetus at the fourth momth. From a "photography and somewhat 1-educed/ (Riidinger.) Upper figure: 1, 2, 6, lamina spiralis; 2, lower plate-, 3, 4, 5, 5, nervus cochlearis; 7, membrane of Reissner ; 8, membrana tectoria : 9, epithelium ; 10, 11, pillars of Corti ; 12, inner hair cells; 13, outer hair cells; 14, 16, membrana basilaris; 15, epithe- lium in the sulcus spiralis ; 17, 18, 19, ligamentum spirale ; 20, spiral canal below the membrana basilaris. Lower figure : S T, S T, 5, 6, 7, 7, 8, 8, scala tympani ; S V, S V, 9, 9, scala vestibuli ; 1, base of the cochlea ; 2, apex ; 8, 4, central column ; 10, 10, 10, 10, ductus cochlearis; 11, branches of the nervus cochlearis ; 12, 12, 12, spiral ganglion ; 13, 14, limbus lami- nae spiralis ; 15, membrane of Ileissner ; 16, epithelium ; 17, outer hair cells ; 18, epi- thelium of the membrana basilaris ; 19, nervous filaments ; 20, union of the membrana basilaris with the ligamentum spirale ; 21, epithelium of the peripheral wall of the ductus cochlearis ; 22, 23, membrana tectoria ; 24, spiral canal below the membrana basilaris. FUNCTION OF SEMICIRCULAR CANALS. 215 den, he had a pain in his head, was very giddy, fell in the shrubs, and vomited. This was plainly ear vertigo, as he himself knew. Bnt he had the following diagnoses made of his case by other medical men : 1, nothing ; 2, nervousness ; 3, deranged stomach." That some persons who are deaf in one ear are absolutely unconscious of it is too often noticed to be now disputed. Gowers ' lays stress upon this point in the following words : '' The fact that the patient may be unconscious of a most sig- nificant auditory defect lessens the value of former observa- tions as evidence of the definite character of stomachal ver- tigo. My own conviction is that, in the vast majority of cases in which a vertigo of definite and uniform character is apparently excited by gastric disturbance, an auditory defect will be discovered on careful examination." Patients afflicted with diseases of the ear may, in some cases, make themselves dizzy by pressure upon the ear of the affected side ; ' while oscillatory movements of the eyes may occasionally accompany the vertigo dependent upon disease of the acoustic apparatus. It is well known that the semicircular canals within the temporal bone, when diseased, are liable to create the so-called Meniere's malady, in which constant vertigo is a prominent symptom ; and experiments upon birds and animals ' seem to show that, in some unknown way, these canals affect coordi- nation of movement and tend to preserve the equilibrium of the body. When the horizontal canal of the bird is cut, the head is constantly moved from side to side ; when the posterior verti- cal canal is cut, the head is moved up and down ; when the anterior vertical canal is severed, the movement of the head is in a diagonal direction. If section of either of these canals be made, upon both sides of the head, the movements of the head above described are permanent ; but, if made on one » "Brit. Med. Jour.," April, ISYV. 2 Schwaback, as quoted by Hughlings-Jackson. ^Flourens, 1824; Crum Brown, "Jour. Anat. Phys.," 18T4; Cyon, "Thfese pour le doctorat in medicine," as quoted by Foster. 216 THE CRANIAL NERVES. side only, they tend to disappear within twenty-four or forty- eight hours.' If the same class of experiments be made upon rabbits, the movements of the head are less marked, but oscil- lating movements of the eyeballs (nystagmus) are developed ; while, if made upon certain other animals, a loss of coordina- tion in the movements of the body and limbs is sometimes produced/ When a person is rotated for some time, a sense of vertigo is produced ; and this symptom seems to warrant the supposi- tion that some abnormal effect is produced within the semicir- cular canals, through the auditory nerve filaments, possibly as a result of concussion of the fluids of the ear against the bony wall.' The following quotation from Michael Foster,* in discuss- ing the different theories advanced to explain coordination of movement and the various reflex phenomena which are con- stantly brought to the notice of the physiologist, seems par- ticularly applicable to the practical branches of medicine : ''All day long, and every day, multitudinous afferent im- pulses, from eye and ear, and skin and muscle, and other tissues and organs, are streaming into our nervous system, and, did each afferent impulse produce its correlative motor impulse, our life would be a prolonged convulsion. As it is, 1 E. Cyon, ojD. d<., 1878. 2 The experiments of Arthur Bottcher, made in 1872, seem to conflict with those of Cyon, Goltz, and Flourens, as to the function of the semicircular canals. He claims that the section of either canal can be made without causing any symptoms of incoordination, provided the auditory nerve filaments are not pulled upon. The fact that the auditory nerve is not bound down at any point between the brain and the labyrinth explains, ac- cording to this observer, why the sligMest traction upon it may injure its attachment to the medulla, and thus create the symptoms described by Cyon, Goltz, and Flourens. ^ A. H. Buck, in a late treatise, reiterates his former statement, that nerves are not found in the semicircular canals, except in the ampullae. This fact he adduces in sup- port of the theory that they have no relation to the perception of sound impulses. He also claims that the small size of this portion of the membranous labyrinth, as compared with the diameter of the bony excavation, coupled with the peculiar reticulated arrange- ment which exists in the space between the membranous tube and the bony wall, further sustains his objection. This author seems to claim that the semicircular canals act as a means of relief to extreme intra-cochlear pressure. Certainly, more light is needed upon the construction of this portion of the internal ear, before its function can be positively determined. 4 Op. cit. FUNCTION OF THE TYMPANIC MUSCLES. 217 by the checks and counter- checks of cerebral and spinal activ- ities, all these impulses are drilled and marshaled, and kept in hand, in orderly array, till a movement is called for ; and thus we are able to execute at will the most complex bodily manoeuvres, knowing only wJiy^ and unconscious, or but dimly conscious, how we carry them out." The tensor tympani muscle^ which has previously been mentioned as deriving its motor power from the fifth nerve and otic ganglion, is of use, even in the quiescent state, in preventing the membrana tympani from being pushed too far outward. During its contraction, the membranous drum of the ear is made tense, for the purpose of deadening some sounds or of favoring the reception of others, by bringing the tension of the membrane in more perfect attune to the sounds which fall upon it. It may, therefore, be considered in some respects as an analogue to the ciliary muscle of the eye, since both act as a sort of accommodation to a mechanism. In some persons, this muscle is under voluntary control, and thus a crackling sound may be produced within the ear at will, or discords be produced when musical sounds are being listened to. The stapedius muscle, which derives its motor power from the facial nerve, is supposed to regulate the movements of the stapes (one of the small bones of the middle ear), and espe- cially to prevent any sudden or excessive movement of the membrana tympani from forcing its base too far into the fenestra ovalis. The Eustachian tube is unquestionably open during the act of swallowing, but it is stiU disputed whether it remains permanently open or is open at intervals. The swelling of the mucous membrane which lines the tube, in catarrhal inflammation, interferes with the entrance of air into the middle ear, and is frequently associated with that peculiar ringing or buzzing in the ear so often present during attacks of influenza. One of the functions of this tube is undoubtedly to afford a means of exit for the secretions of the cavity of the middle ear, and, in case of inflammation of that cavity, 218 THE CRANIAL NERVES. should the Eustachain tube become closed, perforation of the drum will ensue, when the presence of the accumulated pus creates imperfect nutrition of that membrane and consequent ulceration of its coats. Waves of sound can and do reach the endolymph of the internal ear by direct conduction through the skull. Since, however, sonorous vibrations are transmitted from the air to solids and liquids (and most sounds come to us through the air), some special apparatus is required to thus transfer the aerial vibrations to the fluids of the labyrinth. The late me- chanical devices, recommended for the relief of perfect deaf- ness, in which the teeth are used as a conducting medium, have not as yet fulfilled the predictions of their inventors. ' The deafness which often follows suppuration of the mid- dle ear does not necessarily indicate any diseased condition of the auditory nerve, since it may be the result of perfora- tion of the memhrana tympani^^ or of an abnormal condition of the hones of the middle ear, both of which might interfere most seriously with the transmission of sound. Foreign bodies in the ear often create most alarming symptoms ; and even an accumulation of wax, pressing on the drum, may create a mental condition strongly resembling the excitement of alcohol or mania.' Even syringing the ear has been known to produce fainting and severe attack of audi- tory vertigo. Prolonged suppuration of the middle ear may be the direct cause of fatal inflammation of the meninges of the brain. Neuroses of the 'acoustic nerve are, of necessity, more ob- scure and difficult of detection than those of the other special * It has long been the custom with otologists to use a tuning-fork, placed upon the forehead (when in vibration), to determine between disease of the middle ear and that of the labyrinth ; since in the former the affected ear hears the tuning-fork most plainly, while, in the latter, the unaffected ear hears it most distinctly. * Perforation of the extcT^al drum of the ear does not necessarily create deafness. That remarkable case, reported by Sir Astley Cooper, when both drums were nearly de- stroyed and where the patient could still hear ordinary conversation, illustrates this point. * See case of a louse in the ear, reported by Hughlings-Jackson, '* Lancet," October, 1880. NEUROSES OF THE AUDITORY NERVE. 219 senses ; since the tests of normal sight, smell, and taste are much more easy and satisfactory than the appreciation of the faculty of a fine discrimination on the part of the patient be- tween notes of a different pitch and quality. To what extent the original and exhaustive researches of Brenner,* as to the value of the galvanic current in the diagnosis of abnormal con- ditions of the nerve filaments within the chambers of the laby- rinth, will be sustained by pathological and clinical investiga- tion, it is difficult now to say ; but it certainly appears to shed some light upon a field of diagnosis which has been almost unexplored on account of the difficulties which have hitherto existed. It will exceed the scope of this volume to enter into the detail of this new method, since the principles of the manifestation of the electric current upon nerve tissue would have to be explained, and the different formulae of nerve reac- tion given. It can, however, be stated that the principle con- sists of obtaining certain sensations by means of the auditory- nerve filaments, when one moistened pole of an electric bat- tery is placed upon the tragus or the auditory meatus, and the other to the back of the neck or the inner side of the arm, and the intensity of the current regulated by means of the rheostat.'' By this means the condition of acoustic hyper- sesthesia and of anaesthesia may be detected with an accuracy which older methods could not afford. The state of acoustic hyper cesthesia may be of central origin or dependent upon some peripheral cause. If due to the former, it may be developed in connection with chronic cephalalgia, hysteria, insanity, cerebral hypersemia, and with irritative conditions of the brain or spinal cord. It is some- times associated with hallucinations of hearing, especially if present as a complication of insanity. The peripheral causes of this condition comprise anything which can pro- duce an exaggeration of the tension of the muscles or bones of the middle ear, thus resulting in a constant compression of the internal structures of the labyrinth. The experi- ments of Lucae seem to point to the tensor tympani mus- 1 As discussed in detail by Erb, Rosenthal, and others. ^ Erb's rule. 220 THE CRANIAL NERVES. die as the agent in accommodating the bones of the middle ear to the keenest appreciation of musical tones^ while the stapedius muscle presides over the accommodation for shriller and non-musical auditory sensations. AVe can thus under- stand, if this be true, how paralysis of the stapedius muscle would create an hypersesthesia of the acoustic apparatus, and, as this muscle may be affected in facial paralysis, how all of the causes of that condition may be the exciting causes also of this affection of the ear.' The state of ancesthesia of the auditory nerve is always associated with some severe and persistent defect in hearing, since the filaments of the auditory nerve are no longer able to transmit the impressions of sound. Its causes are but poorly understood, but it seems positive that lesions of the posterior regions of the meso-cephalon, the medulla, and cerebellum, as well as new growths at the base of the brain, excessive intra- cranial pressure, and local disease of the labyrinth itself, may be thus manifested. The deafness which follows the exan- thematous fevers, and is observed in hysteria and ataxia, usually indicates changes in the meninges of the brain, which, if severe, produce an incurable loss of hearing. Malforma- tions of the internal or middle ear, either congenital, or ac- quired during childhood after cerebral diseases, are the com- mon causes of deaf-mutism. THE GLOSSO-PHARYNGEAL, OR NINTH NERVE. Like the two previous nerves, both the superficial and deep points of origin of the glosso-pharyngeal nerve are situ- ated in the medulla oblongata, a separate gray nucleus in the floor of the fourth i^entricle being ascribed to it." This nerve escapes from a groove between the lateral tract and the resti- form body of the medulla, lying below the auditory nerve and above the pneumogastric, and passes out of the cavity of ' This may be deemed incompatible with statements made on page 194 of this vol- ume, as the tensor tympani muscle was there stated to be an agent in creating auditory defect in Bell's paralysis. ' Ferrier, " Functions of the Brain," London, 1876. THE GLOSSO-PHARYNGEAL, OR NINTH NERVE. 221 the cranium by the jugular foramen, where it lies in close relation with the pneumogastric and spinal accessory nerves, the jugular vein, and the inferior meningeal artery. It pos- sesses motor and sensory fibers, and fibers which assist in the appreciation of the special sense of taste. ,.... -..-.J Fig. 19. — Glosso-pharyngeal nerve. (Sappey.) 1, large root of the fifth nerve ; 2, ganglion of Gasser ; 3, ophthalmic division of the fifth ; 4, superior maxillary division ; 5, inferior maxillary division ; 6, 10, lingual branch of the fifth, containing the filaments of the chorda tympani; 7, branch from the sub- lingual to the lingual branch of the fifth ; 8, chorda tympani ; 9, inferior dental nerve; 10, terminal filaments of the lingual nerve; 11, submaxillary ganglion ; 12, mylo-hyoid branch of the inferior dental nerve; 13, anterior belly of the digastric muscle; 14, section of the mylo-hyoid muscle; 15, 18, glosso-pharyngeal nerve; 16, ganglion of Andersch ; 17, branches from the glosso-pharyngeal to the stylo-glossus and the stylo-pharyngeus muscles; 19, 19, pneumogastric; 20, 21, ganglia of the pneumogastric; 22, 22, superior laryngeal nerve; 23, spinal accessory; 24, 25, 26, 27, 28, sublingual nerve and branches. By reference to the diagram,' it will be perceived that two ganglioform enlargements are developed upon this nerve, the upper one being situated on a level of the upper opening of ' See Fig. 80, on the following page. 222 THE CRANIAL NERVES. the jugular foramen, while the I Fig. 80. — A diagram of tJie branches of the ninth cranial or glosso-pharyn- geal nerve. 1, filaments of origin, extending into the medulla oblongata ; 2, the jug- ular foramen, through which the nerve escapes from the cranium ; 8, the jugular ganglion, developed upon the nerve in the jugular fora- men ; 4, the ganglion of Andersch, or the ^^ petrous ganglion "/ 5, the auricular branch, deriving a fila- ment also from the pneumogastric nerve ; 6, a communicating branch to the pneumogastric nerve; 7, a communicating branch to the sym- pathetic nerve; 8, the tympanic branch or " Jacobson's nerve,^^ dis- tributed to the middle ear; 9, a communicating branch to the carot- id plexus of the sympathetic ; 10, the tonsillar brandies, distributed to the tonsil ; 11, a portion of the plmryngeal plexus, formed also by the pneumogastric nerve; 12, the lingual branches, distributed to the mucous membrane and the papillae of the base and sides of the tongue. lower one lies slightly below the foramen. To the first, the name '' jugular ganglion " is ap- plied, while the second is called the '' ganglion of Anderscli^^^ after its discoverer. These two ganglia do not include the same relative proportion of nerve fibers derived from the glosso-pharyn- geal, since the jugular ganglion is developed upon only a por- tion of the nerve, while the ganglion of Andersch includes all the filaments of the trunk of that nerve. Within the jugular foramen, the glosso-pharyngeal nerve lies in front of the spinal accessory and pneumogastric nerves, which are separated f rona it by a sheath which invests the two latter, and it bears an intimate relation with the jugular vein within the fora- men, and also in the neck. As a motor nerve^'' the glosso- pharyngeal supplies the levator palati, azygos uvulae," stylo- pharyngeus, and the middle constrictor of the pharynx ; while, as a nerve of general sen- ^ It is extremely doubtful if the glosso- pharyngeal nerve possesses any motor fiber- which are not derived from other nerves by filaments of communication. ' These muscles, if supplied by this nerve (as experiments seem to show), are reached by fibers sent to the facial nerve, and after- ward, by means of the great petrosal branch, to Meckel's ganglion. DISTRIBUTION OF GLOSSO-PHARYNQEAL NERVE. 223 sation^ it supplies the root of the tongue, the soft palate, the pharynx, the Eustachian tube, and the tympanum. It will be thus perceived that the glosso-pharyngeal nerve possesses. Fig. 81. — PapillcB of the tongue. (Sappey.) 1, 1, circumvallate papillae; 2, median circumvallate papilla, which entirely fills the fora- men caecum ; 3, 3, 3, 3, fungiform papillae ; 4, 4, filiform papillae ; 5, 5, vertical folds and furrows of the border of the tongue ; 6, 6, 6, 6, glands at the base of the tongue ; 7, 7, tonsils ; 8, epiglottis ; 9, median glosso-epiglottidean fold. within itself^ all the necessary fibers to insure those succes- sive acts of a reflex type which occur during deglutition,' ^ It is denied by some physiologists that the sensory filaments^ which are the main agents in exciting the reflex acts perceived during deglutition, are those of the glosso- pharyngeal nerve ; since the sensory filaments of the fifth nerve distributed to the palate and pharynx from Meckel's ganglion seem to also fulfill that important function. 224 THE CRANIAL NERVES. and it is by this nerve that the second act of deglutition is chiefly excited and performed. The sense of taste^ which is afforded by the glosso-pharyn- geal, is confined to the posterior third of the tongue. A sim- ilar distribution of its sensory fibers is remarkably illustrated in that case of Hilton's/ where an attack of tonsillitis pro- duced a sympathetic furring of the posterior third only of the lateral half of the tongue. Though analogy would lead us to suppose that a stimulus applied to any part of the course of the gustatory fibers of the glosso-pharyngeal nerve would give rise to a sensation of taste and nothing else, the proof is not forthcoming ; since this nerve, as before stated, is a mixed nerve containing sen- sory fibers as well as those of taste. Fig. 82. Fig. 83. Varieties of papillce of the tongtte. (Sappey.) Fig. 82. — Medium-sized circumvallate papilla: 1, papilla, the base only being apparent : it is seen that the base is covered with secondary papillae ; 2, groove between the papilla and the surrounding wall ; 3, 3, wall of the papilla. Fig. 83. — Fungiform, filiform, and hemispherical papillae: 1, 1, two fungiform papilla?, covered with secondary papillae ; 2, 2, 2, filiform papillae ; 3, a filiform papilla, the prolongations of which are turned outward ; 4, a filiform papilla, with vertical pro- longations ; 5, 5, small filiform papillas, with the prolongations turned inward ; 6, 6, filiform papillae, with striations at their bases ; 7, 7, hemispherical papillae, slightl\ apparent, situated between the fungiform and the filiform papillae. Bitter substances are most tasted upon the haclc of tin tongue^ and sweet substances when placed npon the tip; a point not without value in administering medicines. The ' " Rest and Pain." For similar effects due to the fifth nerve, see a previous lecture. '^ Mich. Foster, op cit. FUNCTIONS OF GLOSSO-PHARYNGEAL NERVE. 225 so-called "gustatory buds," which by some have been re- garded as specific organs of taste, are found also upon the epiglottis, which is wholly devoid of taste ; hence their func- tion can not as yet be considered as fully determined. As a means of refreshing your memory, the following classification of the branches of the glosso-pharyngeal nerve may prove of value. It will be seen that the tympanic branch, or Jacobson's nerve, is specially important, since it supplies portions of the middle ear which have been studied, when the auditory nerve was discussed, in their relation to the mechan- ism of hearing ; and also because it gives a filament to two of the petrosal nerves, whose functions have been considered in connection with the seventh cranial nerve.* A TABLE OF THE BKANCHES OF THE GLOSSO-PHARYNGEAL KERVE 1. Tympanic branch, or Jacobson^s nerve. Glosso-pharyngeal (Ninth Cranial) ■> Nerve, rommunicaiina f Large petrosal nerve, filaments to ^ g^^„ petrosal nerve. r>„„„ . ^„ ^f f Fenestra ovalis, Branches of I j,^^^^^^^ ^^^^^^ duirzbutton to ] Eustachian tube. 2. Carotid branches. 3. Pharyngeal branches (help to form the pharyngeal plexus). 4. Muscular branches (to muscles of the pharynx). 5. Tonsillar branches (help to form the tonsillar plexus). 6. Lingual branches. EFFECTS OF SECTION^. Section of the glosso-pharyngeal nerve is followed by a type of paralysis, in which deglutition becomes an act of extreme difiiculty, and in which regurgitation of food into the nostril is particularly liable to occur. The sense of taste in the pos- terior third of the tongue is furthermore completely destroyed, thus tending to prove that the gustatory fibers are inJierent to the nerve itself, and not the result of a communication between ^ Flint ascribes to the chorda tympani nei-ve the ability to perceive only saline, acid, and styptic qualities ; and to the glosso-pharyngeal nei've, the appreciation of sioeet, alka- line, bitter, and metallic tastes. 2 Copied from the " Essentials of Anatomy " (Darling and Ranney). Putnam's Sons, New York, 1880. 226 THE CRANIAL NERVES. it and some other nerve, as is claimed in reference to the gus- tatory fibers of the fifth. ' It is stated, by some of the later investigators upon this subject, that the sense of taste is not alone confined to the tongue, but exists also in the pillars of the fauces and the walls of the pharynx^ and that section of the glosso-pharyn- geal nerve causes an entire abolition of this power of special sense in these latter regions, as well as in the posterior third of the tongue." THE ACT OF DEGLUTITION AKD ITS MECHANISM. The act of deglutition is, perhaps, more properly con- nected with the glosso-pharyngeal nerve than with any other, although that nerve assists in the performance of one stage only of the entire act. For convenience of description, it has been the custom of physiologists to divide the act of degluti- tion into three distinct periods. The first period, comprising Fig. 84. — Taste buds from the lateral taste organ of the rabbit. (Engelmann.) the passage of the bolus of food through the mouth, which is under the control of the voluntary muscles ; the second, the passage of the bolus through the isthmus of the fauces and the pharynx ; the third, the passage through the oesophagus to the cavity of the stomach. In the first period, the food is first seized by the lips, then ' See previous lecture on the fifth nerve, and also the lecture upon the facial nerve. ' Experiments seem to point to the fungiform and circumvallate papillce of the tongue as the chief agents in perceiving taste, if the " taste buds " of Lo\v6n and Schwalbe are accepted as proven. See Fig. 84. THE PHYSIOLOGY OF DEGLUTITION. 227 forced between the jaws by the tongue and the buccinator muscles ; and by the teeth it is not only masticated, but is also mixed with the salivary secretion. When the food is ready to be swallowed, the mouth is first closed, as the act is performed with extreme difficulty when the mouth is open, be- cause the tongue can not properly act upon the bolus.' The tongue now becomes widened, so as to offer a large surface to the bolus of food, and, with the bolus placed behind it, is pressed backward along the roof of the mouth. In case the food to be swallowed happens to be in a liquid form, the tongue is so curved that its edges curl upward, while its dorsum is depressed in the center, thus forming a longitu- dinal groove along its entire length ; and the soft palate is so closely applied to the base of the tongue as to admit of a sucking force. The importance of the tongue during this period of the act of swallowing can not be overestimated. Animals, in which the tongue has been paralyzed by section of the nerves of that organ, exhibit the utmost distress in their efforts to bring the food to the back portion of the mouth, and are forced to so toss the head as to bring the force of gravity to their aid." Drinking, also, becomes even more interfered with, and the tongue is no longer used to help in the act ; hence, various devices are used to bring the fluid where the reflex act of the fauces will help to carry it to the stomach. If it were not for the fact that, after removal of the tongue for local disease, the stump was of sufficient length to be of great assistance in controlling the bolus of food, such an operation would be a questionable procedure in surgery. It may be noticed, by those of you who have been follow- ing these remarks with care, that the glosso-pharyngeal nerve has, as yet, had no influence upon the mechanism of degluti- tion, since the buccinator muscles are supplied by the facial nerve, and the tongue by the hypo-glossal nerves, which have * For the clinical proof of this fact, the reader is referred to the effects of "facial diplegia." See page 197. 2 We see this also marked, but to a less extent, in patients afOicted with glosso-labial paralysis. 228 THE CRANIAL NERVES. not, as yet, been described ; but, as the second and third periods of the act are the most complex, and the second most completely under the control of that nerve, the omission of the mechanism of the first period, until the whole could be considered together, was for the purpose of making the sub- FiG. 85. — Cavities of the mouth and pharynx, etc. (Sappey.) Section in the median line of the face and the superior portion of the neck, designed to show the mouth in its relations to the nasal fossae, the pharynx, and the larynx : 1, sphenoidal sinuses ; 2, internal orifice of the Eustachian tube ; 8, palatine arch ; 4, velum pendulum palati ; 5, anterior pillar of the soft palate ; 6, posterior pillar of the soft palate ; V, tonsil ; 8, lingual portion of the cavity of the pharynx ; 9, epi- glottis ; 10, section of the hyoid bone ; 11, laryngeal portion of the cavity of the pharynx; 12, cavity of the larynx. ject more easy of comprehension than if the different periods were considered separately from each other. The effect of section of the inferior maxillary branch of the fifth nerve upon the act of deglutition has been mentioned in a previous lecture, but this effect is due, not alone to an absence of the THE PHYSIOLOGY OF DEGLUTITION, 229 normal muscular power of the muscles of mastication, but also to an anaesthetic condition of the mucous lining of the mouth, which renders the tongue unable to appreciate the situation of the bolus of food ; as has been proven by the fact that the same difficulty exists when section of the fifth nerve is made in front of the ganglion of Gasser, where only the sensory portion of the nerve can be injured, as when both the motor and sensory portions of the nerve are involved, after section below the foramen ovale. In the second period of deglutition, the bolus of food, by being crowded backward, tends to raise the soft palate ; and the levator palati muscle further assists in retaining the palate in this elevated position, while the superior constric- tor muscle of the pharynx causes the posterior wall of the pharynx to bulge forward, and thus to meet the uvula. The posterior nasal openings are thus mechanically closed to the entrance of the food into the chamber of the nose, prepara- tory to the series of reflex movements which are to ensue, for the purpose of forcing the bolus downward into the oesopha- gus, and thence into the stomach. The larynx is now suddenly raised^ so as to bring the superior opening of that organ underneath the base of the tongue, which has been crowded backward during the first period, in order to force the bolus against the soft palate. Its soft structure renders it admirably adapted to mold itself to the irregularities of outline of the laryngeal opening. By this position of the tongue, the epiglottis is also applied over this opening,' and the entrance of food into the larynx is furthermore guarded against by the approximation of the vocal cords by means of the adductor muscles of the larynx. The muscles which thus raise the larynx are the anterior belly of the digastric, the mylo-hyoid, the genio-hyoid, the stylo-glossus, and some of the fibers of the genio-glossus. Simultaneously with the elevation of the larynx, the pa- ' It was formerly supposed that the epiglottis was the chief instrument in prevent- ing the entrance of food into the larynx, but the large number of cases where the epiglottis has been removed, and no difficulty in deglutition apparently produced, have created a doubt as to its importance. ir 2^0 THE CRANIAL NERVES. lato-pharyngeal muscles contract and raise the lower end of the pharynx^ thus shortening the length of that organ and tending to draw the pharynx over the bolus of food, very much as a glove is drawn over the finger ; while, at the same time, the curve of the posterior pillars of the pharynx is Fig. 86. — Muscles of tlie pharifnx, etc. (Sappey.) 1, 2, 3, 4, 4, superior constrictor ; 5, 6, 7, 8, middle constrictor ; 9, 10, 11, 12, inferior con- strictor; 13, 13, stylo-pharyngeus ; 14, stylo-hyoid muscle; 16, stylo-glossus ; 16, hyo-glossus; 17, mylo-hyoid muscle; 18, buccinator muscle; 19, tensor palati ; 20, levator palati. made straight, and, by the approximation of these muscles to the sides of the uvula, the opening of the pharynx into the nares is now completely occluded. The constrictor muscles of the pharynx now come into THi: PHYSIOLOGY OF DEGLUTITION. 231 play, contracting in succession from above downward ; the posterior pillars of the fauces, by their approximation, pre- vent the bolus from again entering the mouth ; and it is thus forced to enter the oesophagus. It is apparent that most of these movements are of a re- ^fl£x character, and are excited by the presence of the bolus Bf food, which passes out of voluntary control as soon as it passes the anterior pillar of the fauces, at which point the second period of deglutition may be said to commence. Every reflex act presupposes some sensory filaments to convey the impression to the brain, and certain motor filaments to trans- mit the impulses to the muscles destined to act upon the bolus ; it is now believed that the ^losso-pharyngeal nerve possesses both of these sets of fibers, as well as those control- ling the special sense of taste. This nerve may then be con- sidered as a nerve of taste, a nerve of motion to the pharyn- geal muscles, and the true ''excitory nerve^^ of the act of deglutition. The importance of the soft palate in the act of deglutition is particularly shown during the swallowing of liquids, since it has to be closely applied to the base of the tongue, in order to allow of a partial vacuum within the cavity of the mouth, and thus to draw the fluid along the furrow formed by the curving upward of the edges of the tongue. This fact is clin- ically shown by patients affected with paralysis of the velum,' who experience great difficulty in swallowing liquids, since the fluid is liable to escape through the nose. A case of this character is reported by Berard, where a young lady was obliged to free herself from all observation whenever she at- tempted to drink, as the escape by the nostrils was so profuse as to occasion embarrassment. The prevention of the entrance of food into the cavity of the larynx, as has been mentioned, is insured : first, by the base of the tongue ; secondly, by the epiglottis ; and, thirdly, > Paralysis of certain muscles of the soft palate occurs when t\ve facial nerve is im- paired behind the point of origin of its petrosal branches. For particulars of this diag- nostic symptom, the reader is referred to page 194. 232 THE CRANIAL NERVES. by the approximation of the vocal cords ; but that such acci- dents do still happen from attempts at inspiration ' during eating is attested by the violent coughing excited, and by the instantaneous expulsion of the foreign substance, unless it should chance to become mechanically arrested in the larynx. Longet accounts for the symptoms excited by such an acci- dent as the result of an exquisite sensibility possessed by the mucous lining of the upper part of the larynx. It is well attested that the danger of entrance of fluids into this organ is far greater than in the case of solids ; and the act of gar- gling is especially liable to be followed by such an occurrence, since the larynx is much wider open than in the act of deglu- tition. In the administration of anaesthetics to patients who have eaten largely before the hour appointed for surgical^ relief, a great danger of the entrance of vomited matters into the cavity of the larynx is encountered, since the sensi- tiveness of the mucous lining is destroyed, and the expulsive efforts of Nature are often wanting.' The third period of the act of deglutition is confined t< the oesophagus, through which the bolus has to pass to read the stomach. The downward movement of the bolus is as- sisted by alternate contraction of the longitudinal fibers oi the tube, which shorten it and tend to draw its walls upward over the bolus, and contraction of the circular fibers, which constrict the tube and force the bolus downward. The fact that gravity has little, if anything, to do with this downward movement is proven by the fact that the position of the body does not seem to affect it, while acrobats are often known to perform the feat while standing upon the head or hands. The time consumed in the passage through the oesophagus was estimated by Magendie " as about two minutes in animals, but ^ As occurs during attacks of laughing, hiccough, etc., when food is present in tlic mouth, or during too hasty an effort to consume food. ^ In cases where this accident occurs, the tongue should be forcibly drawn out of the mouth, 80 as to pull up the epiglottis, and the foreign body extracted by the finger, if possible, or, if not, the patient should be held by the feet, and thus, by shaking the pa- tient, gravity may help to dislodge it. I once saved the life of a man by this means when all others had failed, and fatal asphyxia seemed imminent. ^ " Journal de Physiol." THE PHYSIOLOGY OF DEGLUTITION. 233 it is probably much shorter in man ; although we are often conscious of a delayed termination of the act, and are forced to hasten it by the drinking of fluids, as most of us can attest. It is probable that this peristaltic action of the oesophagus, like that of the intestinal canal, is partly controlled by the nervous influence of the sympathetic system, although the pneumogastric nerves have an extensive distribution to and a very marked control over this organ/ Deglutition is essentially a reflex act^ save in its first period, when volition plays an important part. It can not take place unless some stimulus is applied to the mucous lining of the fauces ; and those apparently voluntary acts of deglutition which are produced when no food is within the mouth are undoubtedly due to the swallowing of saliva, or to irritation of the fauces by the base of the tongue itself. When we tickle the fauces, we can see all of the act of deglu- tition, confined to the second period, artificially produced ; and this irritability of the fauces is so extreme in some per- sons as to render any attempt to examine the throat one of difficulty, and often a cause of reflex vomiting. So impor- tant is the education of the throat to enable the patient to tolerate the presence of instruments, that all surgical proced- ures upon the larynx, if performed from within the mouth, require often months of training to enable the patient to assist the operator in a step whose execution may be a matter of a few seconds only. All forms of local applications are used to insure an anaesthetic condition of these parts, and the in- ternal administration of medicinal agents is, furthermore, often required to render such procedures within the cavity of the larynx possible. That the center for the reflex act of deglutition is confined to the medulla oblongata is proven by experiment on animals whose brain has been entirely removed, with the exception of the medulla, when irritation of i^ie fauces will still continue ^ Michael Foster regards this third act of degUitition as more closely dependent upon the central nervous system than the movements of the intestinal tract, and attributes it to reflex action due to the bolus. 234 THE CRANIAL NERVES. to produce all the movements of the second stage of that act. CLINICAL POINTS OF INTEREST PERTAINING TO THE GLOSSO-PHARYN- GEAL NERVE. The intimate association which apparently exists between the fibers of this nerve and the sense of taste, the movements of the pharyngeal muscles, and the reflex acts excited by the presence of a bolus or of some foreign source of irritation to the isthmus of the fauces and the walls of the pharynx, would seem to suggest that any impairment of the glosso-pharyngeal would be followed by clinical evidences of imperfect perform- ance of each and all of these functions. It is, however, to be regretted that the questions of the course, origin, and func- tions of the chorda tympani nerve, the exact distribution of the fibers of the glosso-pharyngeal nerve to the tongue, and the source from which this latter nerve derives its motor fila- ments, are, as yet, disputed points among physiologists ; and the sources of doubt are not removed, but rather increased, by the results of pathological observation, since they often seem contradictory, and thus prove rather a source of embarass- ment than an aid to definite conclusions. One would naturally suppose, provided that he was fa- miliar with the symptoms of that disease, called by Duchenne ''glosso-labio-laryngeal paralysis" (although the word *' pha- ryngeal" is often used in place of ''laryngeal" to express the same condition), that the difficulty experienced in deglutition would certainly indicate that the nerve which apparently pre- sides over that function would be found in a state of disease ; but, on the contrary, the glosso-pharyngeal nerve is not re- ported, to my knowledge, as having anything to do with that affection. We must, therefore, be forced to infer that the motor filaments of the pharynx are, to a great extent, con- trolled by other nerves ; and that, if they are apparently branches of the ninth cranial nerve, they are to be accounted for as fibers derived from communicating filaments from other sources. CLINICAL CONDITIONS CAUSING HYPERGEUSIA. 235 Hirsclifeld claims to have verified a branch of the glosso- pharyngeal nerve which extends to the anterior two thirds of the tongue ; hence the strong probability that it partially controls the sense of taste in that portion as well as in the posterior third of the organ. Stannius, by experiments, thinks that he has established the function of this branch, and he attributes to it the power of perception of Mtter substances only, the other varieties of taste sensations being presided over by the chorda tympani nerve or the gustatory branch of the fifth nerve. We know, clinically, that the conditions of hypersesthesia and anaesthesia of the gustatory nerves are verified by many interesting phe- nomena ; and we must be content to wait for the solution of the other mixed problems of gustation, until they are solved by further clinical, physiological, and pathological observation. The condition of gustatory hyper cesthesia^ called also ^^ hyper geusia^^^ ' is very marked in certain patients who are in an anaemic and nervous condition, while it is a frequent phenomenon in hysteria and in melancholia. In such cases an apparent gustatory sensation may be often excited by the application of an electric current .to the cervical or upper dorsal region of the spine. True gustatory hypersesthesia may express itself as an in- crease in the delicacy of the gustatory sensation, so that ex- tremely small quantities of sapid substances may be perceived. We thus occasionally meet with hysterical patients, who can perceive the taste of certain medicinal agents in a solution which to the healthy subject would be tasteless. It may ex- press itself, again, as an unnatural enjoyment of food, or a loathing of certain dishes which convey a sense of taste which does not in reality exist. In facial paralysis of rheumatic origin, abnormal gustatory sensations are sometimes present, as sweetish, sour, or sapid tastes, within the mouth. In the insane, hallucinations of the special sense of taste, usually of ^ See experiments of Valentin and Keppler, made to determine the exact degree of gustatory sensibility and excitability. 236 THE CRANIAL NERVES. a disagreeable character, are often present, and indicate some disease of central origin. The condition of gustatory anoesthesia^ called ''ageusia,'''' comprises all those phenomena which indicate either a partial or complete loss of the sense of taste. Thus, the tongue may be able to appreciate certain substances, and be insensible to others, while the anaesthetic condition may be circumscribed or diffused, as regards its anatomical distribution, affecting either the tip of the tongue, its root, or one or both sides. This abnormal state is observed after paralysis of the trige- minus, severe injuries to the trigeminus or the glosso-pharyn- geal nerves, intra-cerebral growths which create compression of the glosso-pharyngeal or trigeminus, ' and atrophy of the nerves, as the result of compression, of disease of their in- herent fibers. As a rule, when this condition exists, we shall find a similar condition of the optic, olfactory, trigeminus, pneumogastric, spinal accessory, or some of the cutaneous branches to the face. THE PNEUMOGASTRIC, OR TENTH NERVE. Owing to the numerous connections of the pneumogastric with other nerves, its varied and extensive distribution, and the important character of its functions, this may properly be regarded as one of the most remarkable nerves of the whole body. It has been often known by the name of the ''par ta- gum,^'' from the wandering course of its fibers, which are distributed to five different vital organs, viz. : the heart, lungs, stomach, liver, and intestines, as well as to many other parts of secondary importance. This nerve, like the seventh, eighth, and ninth nerves, is considered by comparative anatomists as belonging to the ' In the case reported by Bottcher, although aguesia existed, the patient complained of a constant burning and bitterness within the mouth. An autopsy showed the presence of a tumor of the base of the brain, which had caused atrophy of the glosso-pharyngeal and pneumogastric nerves by a steady compression. Longet reports cases where the nerves passing through tho jugular foramen were all more or less destroyed by pressure from a similar cause. THE PNEUMOGA'STRIC, OR TENTH NERVE. 237 class of spinal nerves, since it arises directly and entirely from the upper portion of the spinal cord. Its superficial point of origin lies in the groove between the olwary and' restiform bodies of the medulla, while its deep point of origin may be traced to a gray nucleus in the floor of the fourth ventricle, slightly below the nucleus for the glosso-pharyngeal nerve. There is a very close affiliation between the deep fibers of the pneumogastric and glosso-pharyngeal nerves within the Fig. 87. — Anastomoses of the pneumogastric nerve. (Ilirschf eld. ) 1, facial nerve; 2, glosso-pharyngeal nerve; 2', anastomoses of the glosso-pharyngeal with the facial; 3, S, pneumogastric, loith its two ganglia; A, 4:, spinal accessory; 5, sublingual nerve ; 6, superior cervical ganglion of the sympathetic ; 7, anastomotic arcade of the first two cervical nerves ; 8, carotid branch of the superior cervical ganglion of the sympathetic; 9, nerve of Jacobson ; 10, branches of this nerve to the sympathetic; 11, branch to the Eustachian tube; 12, branch to the fenestra ovalis; 13, branch to the fenestra rotunda; 14, external deep petrous nerve; 15, internal deep petrous nerve ; 16, otic ganglion ; 17, auricular branch of the pneumo- gastric ; \S, anastomosis of the pneumogastric with the spinal accessory; 19, anasto- mosis of the pneumogastric with the sublingual; 20, anastomosis of the spinal acces- sory with the second pair of cervical nerves; 21, pharyngeal plexus; 22, superior laryngeal nerve. substance of the medulla oblongata, so close indeed as to lead some authors to consider them identical with each other. These deep fibers may be traced, in part, into the substance of the restiform body, a small bundle toward the cerebellum, 238 THE CRANIAL NERVES. Fig. 88, — A diagram showing the branches of distribution and communication of the pneumogastric nerve. Cervical portion of nerve. 1, the filaments of origin of the pneumogastric nerve; 2, the spinal accessor i/ nerve escap- ing from the medulla oblongata, below the pneumogastric nerve ; 3, the upper com- municating filament between the pneumogastric and the spinal accessory nerves (often absent); 4, the '"''ganglion of the root^^'' situated in the jugular foramen ; 5, ihc jugu- lar foramai^ showing the transmission of three nerves ; 6, the communicating filament between the pneumogastric and the glosso-phari/ngeal nerves ; 7, the glosso-pfiaryngeal nerve, from its point of origin to its escape from the cavity of the cranium ; 8, the '"'■ganglion of the tiunk''^ of the pneumogastric nerve; 9, the loiver filament of \ GANGLIA OF THE PNEUM0GA8TRIG NERVE. 239 communication between the pieumogastric and spinal accessory nerves, which probably controls the muscles of the larynx concerned in phonation and respiration ; 10, the communicating filament from the arcade, formed by the first and second cervical nerves ; 11, the communicating filament from the facial nerve, which helps to form the auricular branch of the pneumogastric or "Arnold's nerve " ; 12, the three sets of filaments which join the pneumogastric nerve to the superior cervical ganglion of the sympathetic system ; 13, the auricular branch of the pneumogastric, or " Arnold's nerve^'' partly formed by the facial filament (11); 14, the branches to the '■'■ pharyn- geal plexus^'' formed also in part by the glosso-pharyngeal ; 15, the supei'ior laryngeal nerve, supplying the mucous lining of the larynx and the crico-thyroid muscle; 16, the " depressor nerve of the heart,'''' formed by two roots, one from the pneumogastric, and the other from the superior laryngeal nerve ;^ 17, the inferior or recurrent laryngeal nerve, winding around an artery (19), and then returning to the larynx to supply the muscles of phonation ;'' 18, the cervical cardiac nerves (sometimes three in number), going to the cardiac plexus ; 19, the subclavian artery (if on the right side), and the arch of the aorta (if on the left side of the body). and a few toward the cerebrum ; but the larger portion pass to the median line of the floor of the fourth ventricle or de- scend into the substance of the medulla oblongata. The pneumogastric nerve emerges from the jugular fora- men as a single trunk, but immediately develops two gan- glia, the upper of which is called the '-'jugular ganglion,'^'' or the " ganglion of the root^^'^ since it lies close to and some- times within the foramen of that name. After the nerve emerges from the foramen, another ganglion, about one quar- ter of an inch in length, is developed, called the "ganglion of the trunJi^ Within the jugular ganglion, an interchange of fibers takes place between the pneumogastric and spinal accessory nerves ; and it seems clear that the laryngeal and pharyngeal branches (which are among the most decidedly motor of those given off from the pneumogastric) may all, in great part, be traced backward into the spinal accessory nerve. The researches of Valentin, Morganti, Longet, and others seem to prove that the pneumogastric nerve at its root pos- sesses no motor power, but is entirely an afferent nerve, al- though Stilling, Wagner, Muller, Yolkman, and Bernard fail 1 For the physiological effect of stimulation of this nerve, see the late researches of Cyon and Ludwigupon this nerve in the rabbit; also text-books of physiology of Michael Foster, A. Flint, Jr., and others. In man, this nerve is probably associated with one of the cardiac nerves. 2 The filament of the spinal accessory (No. 9 in the cut) is supposed to afford to this nerve its motor power, having simply used the sheath of the pneumogastric as a means of protection in its course down the neck. The physiological imp.ort of this nerve shows the vital necessity for such protection. 240 TEE CRANIAL NERVES. to attribute all the motor fibers of this nerve to either the spinal accessory or glosso-pharyngeal nerves, and maintain that motor fibers may be demonstrated within the root of the pneumogastric above the jugular ganglion. In regard to its trunk, there can be no doubt that the pneumogastric is to be considered as a nerve of double en- dowments, although it is certain that these endowments are very differently distributed among its branches. That it is capable of conveying those impressions which become sensa- tions when communicated to the sensorium is experimentally proved by the fact that, when its trunk is pinched, the ani- mal gives signs of acute pain ; and it is also evident from the painful consciousness we occasionally have of any abnormal condition of the organs which it supplies. BRANCHES OF THE PNEUMOGASTRIC NERVE. The pneumogastric nerve, by means of its numerous points of distribution, participates in the operations of deglutition, phonation, respiration, the circulation of the hlood, and the process of digestion. To fully describe the variations in its course from above downward, and the distribution of its branches to the various organs (in all of their physiological bearings), you must, of necessity, be carried into a discus- sion of the thoracic and abdominal viscera and the physio- logical acts which they perform. A hasty enumeration of the general course of the fibers of this nerve can, therefore, only be given here, reserving the many points of interest connected with it for other lectures, when the viscera will be considered. The efferent fibers of the pneumogastric nerve include cer- tain motor branches which are distributed into the pharynx, the larynx, the oesophagus, the stomach, and the intestinal canal. The pharyngeal branches help to form the pharyngeal plexus of nerves, and thus to aid in the movements of the muscles of that organ during the second period of deglutition. ' ' See lecture upon the glosso-pharyngeal nerve, where the act of deglutition is fully discussed. DISTRIBUTION OF PNEUMOGASTRIC NERVE. 241 It is also probable that these same muscles tend to modify the tone and quality of the mice, and also to assist in the Fig. 89. — TJwracic and abdominal portion of the nerve. 20, the thoracic cardiac nerves, assisting to form the cardiac plexus ; 21, the filaments of communication between the pneumogastric nerve and the thoracic ganglia of the sym- pathetic system ; 22, the branches given off by the pneumogastric nerve to assist in forming the posterior pulmonart/ plexus ; 23, the branches given off to assist in form- ing the anterior pulmonary plexus ; 24, the branches which form the oesophageal plexus, and assist in the performance of the ^hird period of the act of deglutition ; 25, the gastric branches, supplying the coats of the stomach ; 26, the hepatic branches, accompanying the portal system of veins ; 27, the intestinal branches, controlling, to a large extent, the peristaltic action of that canal ; 28, branches which can be traced to the kidneys, the spleen, and the supra-renal capsules. 242 THE CRANIAL NERVES. articulation of sounds or words, although the lingual muscles and those of the lips are more directly concerned in the latter function. Fig. 90. — Distribution of tlic pntamvyudik. (^llii>cliii.iu.; 1, trunk of the left pieumogastric ; 2, ganglion of the trunk ; 8, anastomosis with the spinal accessory ; 4, anastomosis with the sublingual ; 5, pharyngeal branch (the auricular branch is not shown in the figure) ; 6, superior laryngeal branch ; 7, external laryngeal ncrrve ; 8, laryngeal plexus ; 9, 9, inferior laryngeal branch; 10, cervical cardiac branch; 11, thoracic cardiac branch; 12, 13, pulmonary branches; 14, lingual branch of the fifth ; 16, lower portion of the sublingual; 1 6, glosso-pharyngeal ; 17, spinal accessory ; 18, 19, 20, spinal nerves ; 21, phrenic nerves ; 22, 23, spinal nerves ; 24, 25, 26, 27, 28, 29, 30, sympathetic ganglia. The laryngeal branches are two in number, and are called the superior and inferior; although the name " recurrent la- ryngeal nerve" is more often applied to the latter on account PHYSIOLOGY OF PNEUMOGASTRIG NERVE. 243 of the peculiarity of its course, since it winds around the sub- clavian artery before returning to the larynx, upon the right side of the body, while the left nerve winds around the arch of the aorta, and then turns backward, to be distributed to the muscles of the larynx. It is by means of these laryn- geal nerves that the muscles which move the xocal cords^ and thus control the voice, are supplied ; while the same mus- cles are important agents in so adapting the size of the open- ing between the vocal cords, during inspiration, as to allow of an unimpeded entrance of air to the lungs/ As the infe- rior nerve is the one which supplies all of the laryngeal mus- ( les but the crico-thyroid and a portion of the arytenoid, it becomes to the physiologist a nerve of great importance, since the acts of respiration and phonation are directly under its influence. Experiment seems to have proven, however, that the laryngeal nerves, although apparently deriving their mo- tor power from the pneumogastric, are, in reality, but fibers of the spinal accessory nerve^ which have used the sheath of the pneumogastric nerve simply for protection in their pas- sage through the neck. The spinal accessory nerve is, there- lore, sometimes called the "superior respiratory nerve of ]3ell," since it controls the movements of the laryngeal mus- cles during the act of inspiration ;'' which are the highest, in point of situation, of any of the respiratory muscles. The branches to the oesophagus, stomach, and intestine are the principal agents in promoting the peristaltic action of the alimentary canal, and they thus aid in the acts of degluti- tion and digestion. It is probable, also, that the pneumo- gastric nerves are capable of directly affecting the secretions of the alimentary canal, although the sympathetic system is ^ The researches of Bernard have done much to call professional attention to the fact that the pneumogastric and spinal nerves are alone involved in ordinary respiration, but that, when it becomes necessary to bring the respiratory movements into perfect accord with the requirements of animal life (as in adapting the action of the muscles of the larynx to production of voice), the spinal accessory nerve becomes an indispensable aid. 2 This statement is one that will admit of question. The reader is referred to the experiments of Bernard and Bischoff (as given on a subsequent page) for the difference i)ctween the effect of the spinal accessory fibers upon the glottis from those of the pneu- mogastric itself. 2U THE CRANIAL NERVES. still regarded as the means by which these nerves exert their influence upon that portion of the body. Fig. 91. — Nei'ves of the larynx, posterior Fig. 92. — Nerccs of the larynx, lateral vieio. (After Sappey.) view. (After Hirschfeld.) Fig. 91. — 1, 1, superior laryngeal nerves passing through the thyro-hyoid membrane ; 2, J external laryngeal branch supplying the crico-thyroid muscle; 3, ascending brancht- distributed to the mucous membrane of the tongue ; 4, transverse branches distribu- ted to the mucous membrane of the epiglottis and the aryteno-epiglottidean folds ; 5, descending branches passing to the mucous membrane covering the posterior surfac<' of the larynx (two of these, of considerable size, cross the arjrtenoid muscle to suppl> the mucous membrane lining the walls of the vestibule); 6, branch connecting tin superior with the inferior laryngeal nerve ; Y, the same branch divided near its point of origin ; 8, 8, inferior laryngeal nerve ; 9, branch to the posterior crico-arytenoid muscle, which is here divided in order to show the next nerve ; 10, branch to the arytenoid winding under the lower border of the muscle so as to enter it from its inner surface; 11, branch to the lateral crico-arytenoid muscle; 12, branch to the thyro-arytenoid muscle. Fig. 92. — a, section of the hyoid bone ; 6, section of the thyroid cartilage ; c, thyro-hyoid membrane ; d, cricoid cartilage ; e, trachea ; /, oesophagus ; g, epiglottis ; /t, superior cornu of the thyroid cartilage ; «', great cornu of the hyoid bone ; k, lateral thyro-hyoid ligament ; /, thyro-hyoid membrane ; m, posterior crico-arytenoid muscle ; n, lateral crico-arytenoid muscle ; o, thyro-arytenoid muscle ; /), base of the tongue ; 1, recur- rent laryngeal nerve ; 2, branches given off from this nerve to the posterior crico- arytenoid muscle ; 3, branch to the lateral crico-arytenoid muscle ; 4, branch to tin thyro-arytenoid muscle ; 5, branch to the aiytenoid muscle ; 6, right superior laryn- geal nerve ; 7, anastomosis of this nerve with the inferior laryngeal ; 8, descending branches from the superior laryngeal ; 9, middle branches of the same nerve ; 10, ascending branches. In addition to the branches, which are considered as of the greatest physiological importance, certain other motor fibers I PHYSIOLOGY OF PNEUMOGASTRIC NERVE. 245 are now traced with tolerable certainty to the trunk of the pneumogastric nerve, which are not unimportant. Thus we may include certain nerves which supply the plain muscular fibers of the trachea and of the larger bronchial tubes, fibers which exert a vaso -motor ial influence upon the blood-vessels of the lungs, an inJiihitory nerve for the heart, and certain libers which are distributed to the lungs and the heart, which are supposed to exert a trophic influence. The properties and functions of the cardiac nerve, and in what way the pneumogastric nerve influences the action of the heart, are physiological questions of the greatest impor- tance. It is now known that section of the pneumogastric in the neck, instead of arresting the action of the heart, in- creases the frequency of its contractions ; while galvanism of the divided ends causes the heart's action to stop during its diastole, if the current be a powerful one, and, if a weak one, the heart's action is propor- tionately slowed. The depressor nerve of the Jieart is shown,' in the diagram- matic representation of the pneu- mogastric nerve and its branches, to arise from two filaments, derived, respectively, from the pneumogastric and the superior laryngeal nerves. The importance of this nerve in explaining ' For the method of origin of this nerve, see the diagrammatic plate of the upper half of the pneumogastric nerve, page 238. While the diagram illustrates the construc- tion of this nerve, as found in the rabbit by Cyon, it is still questionable whether a simi- lar method of origin can be demonstrated in man. That the nerve exists is not a matter of doubt ; but it is impossible to positively state its method of origin or its precise course. 18 Fig. 93. — Branches of the pneumogastric to the heart. (Bernard.) C, heart ; a, carotid artery going to the brain ; w, branches of the pneumo- gastric going to the heart. 246 THE CRANIAL NERVES. many physiological effects of galvanism of the pneumogastric has been developed through the efforts of Cyon and Ludwig, in their prize essay of 1867, who showed to the profession its power of decreasing the beats of the heart, and who thus afforded the means of satisfactorily explaining many phe- nomena met with in the daily practice of medicine. If the abdomen of a frog be exposed, and the intestine struck sharp- ly, the heart will be seen to stand still, as if the depressor nerve of the heart had been galvanized ; while stimulation of the mesenteric nerves, before they join the sympathetic chain, will have a like result. It has been found that the irritation of an inflamed peritoneal surface, even if gently practiced, will decrease the heart pulsations, and that severe shock or nery intense pain^ no matter where it arises^ wiU also have the same effect upon the heart. Such evidences of reflex action are apparently transmitted through these depressor nerves of the heart alone, and they help us to explain why pain may create, in the human race, attacks of fainting, and why some types of inflammatory dis- eases and states of collapse and shock are associated with a decrease in the pulsations of the heart. The action of atropin^ even in small doses, seems to entirely arrest the influence of this nerve upon the heart, and a guide to the administration of this drug may thus be derived from physiology, while the effects thereof may, in some instances, be thus made clear. The cardiac nerves of the pneumogastric are undoubtedly connected with the other nerves of the cardiac ganglia^"^ and act upon the heart fibers indirectly, rather than directly, with- out the intervention of the ganglion. It has lately been proven that certain other cardiac nerves^ whose function is accelera- tory, rather than depressing, to the heart, cau be traced to the cervical portion of the spinal cord as their point of origin, but they have no connection with the pneumogastric nerve. ' The vasomotor nerves of the lung are derived, according to Franck, from the upper cervical ganglia of the sympathetic, their primary origin, however, being in the ccrvico- dorsal region of the cord. PHYSIOLOGY OF PNEUMOGASTRIG NERVE. 247 The afferent fibers of the pneumogastric nerve, or those which carry impressions from the periphery of the nerve to- ward its point of origin, comprise the sensory filaments ' dis- tributed to the entire respiratory tract ; and also those sensory nerves which supply the pharynx, the oesophagus, and the stomach ; fibers which assist to produce the secretion of the saliva ; fibers which tend to arrest the secretion of the pan- creas ; a special inhibitory nerve upon the vaso-motor center of the medulla oblongata ; and, finally, a special set of fibers which both augment and retard, at will, the action of the respiratory center of the medulla oblongata. As the pneumogastric nerve is more apparently, although perhaps not more importantly, connected with the act of respi- ration^ we will first consider the two sets of fibers which have been mentioned above as influencing the action of the respira- tory center. It has been shown by Rosenthal that the supe- rior laryngeal nerve, when stimulated by a galvanic current, decreases the number of respirations, while the main trunk of the pneumogastric nerve, when similarly stimulated, tends to increase the number of respirations. Thus, the fact that the vagus nerve possessed two sets of respiratory fibers^ an acceleratory and an inhibitory, seems to be well established, although some observers have not, as yet, admitted the posi- tiveness of the experiment. As regards those branches of the pneumogastric which seem to exert a specific infiuence upon the various secretions of the alimentary canal, we have yet much to learn. As a general rule, it may be stated that anything which tends to create an increased activity in the epithelial cells, rather than in the blood supply of the part, tends also to increase the se- cretion. Thus a drug may excite any special secretion, first, ' Sommerbrodt (" Centralbl. f. d. med. Wiss.," December, 1880) points out a mechan- ism of compensation by which the action of the lungs and of the heart is coordinated. Thus, a rise in the intra-bronchial pressure (as occurs in singing, crying, coughing, etc.), by irritating the sensory nerves of the lungs, excites a reflex depressing action on the vaso-motor and cardio-inhibitory nerves. The resulting vascular dilatation and accelera- tion of the heart's action react upon the lung in two ways. They prevent the natural ten- dency to stasis of the blood in the bronchial walls, and they insure the rapid renewal of oxygen, demanded by the increase in pulmonary activity. 248 THE CRANIAL NERVES. by acting upon the nerve center which controls that part ; secondly, by a reflex act through the nerves of the part ; thirdly, by acting as a direct chemical stimulus to the cells ; and, fourthly, by increasing the amount of blood in the part, through dilatation of the blood-vessels. That an iuMMtory effect upon the vaso-motor center of the medulla is possessed by some of the fibers of the pneumogas- tric nerve, is proven by the effect of galvanism of the vagus upon blood pressure ; since, when the depressor nerve of the heart is divided and the end connected with the brain is gal- vanized, the blood pressure falls, although the heart is not affected, as it would be if the cardiac portion of the nerve were stimulated. COURSE OF THE PNEUMOGASTRIC NERVE OF THE TWO SIDES. The important functions of the vagus render it necessary that every precaution shall be taken by Nature to prevent its possible injury, especially during its passage through the neck ; since, within the thorax and the cavity of the abdomen, the viscera and the bony encasements tend to render all possi- ble dangers of injury a minimum. We therefore find this nerve inclosed within the sheath of the carotid artery, where it is placed between the artery and the internal jugular vein, lying also posteriorly to them both. By this provision the nerve is placed between fluid upon either side, and thus all danger of transmitted force affecting it is obviated, while the deep situation of the carotid and the close proximity of the transverse processes of the cervical vertebrae make the nerve secure from the danger of wounds of pointed instruments. It is almost an impossibility, therefore, for this nerve to become involved in any form of accident, without the large vessels of the neck being simultaneously injured and the patient sacri- ficed. Even in the jugular foramen the nerve is wrapped in the same sheath as the spinal accessory nerve, and it is placed behind both the glosso-pharyngeal nerve and the jugular vein ; while, to reach the commencement of the common ca- SECTION OF PNEUM0GA8TRIC NERVE. 249 rotid artery, the nerve is placed in close relation to the inter- nal carotid artery and the jugular vein. As the nerves of either side reach the lower portion of the neck, each takes a different course. The right nerve passes between the subclavian artery and vein, then along the side of the trachea, then to the back of the root of the lung, then along the side of the oesophagus as two cords, then as a single cord along the back of that tube through the oesophageal opening of the diaphragm, and terminates in the solar and splenic plexuses, after giving off branches to the posterior surface of the stomach, and some filaments to the liver. The left nerve passes between the left common carotid and left subclavian arteries and behind the left innominate vein, then arches across the aorta and passes to the back of the root of the lung, then as two cords along the sides of the oesophagus, where it joins with its fellow to form the oesophageal plexus, then, as a single cord, in front of the oesophagus through the oesophageal opening of the diaphragm, when it supplies the anterior surface of the stomach and probably terminates in the hepatic plexus. THE EFFECTS OF SECTION OF THE PNEUMOGASTBIC NERVE. The effects of section of both of the pneumogastric trunks,' if made below the jugular ganglion, are most markedly ex- hibited in the larynx, the lungs, and the heart. Effects upon the Larynx.— The larynx becomes impaired in its function, and the glottis remains partially closed by the vocal cords, whose abductor muscles are now paralyzed, thus impeding the free entrance of air into the lung ; and, as a consequence of this, the respirations are, for a short time, hurried and difficult, although they soon become diminished in frequency.' The inspiratory effort becomes unusually * Animals usually survive after one vagus nerve is divided, and present only a hoarse- ness of voice ; an increased frequency of respiration, emphysema, or pulmonary congestion may be a sequel to the operation. Union of the divided nerve has been observed in numerous instances. 2 Were it not for the nerves of the skin, and other sensory nerves which can transmit the feeling of pain, and which also possess the power of exciting respiratory efforts, sec- tion of both vagi ought, theoretically, to stop respiration at once. 250 THE CRANIAL NERVES. slotv, while expiration is remarkably rapid and sometimes audible ; tlie intercostal spaces sink inward during the eleva- tion of the ribs, showing that the lungs are not fully inflated with air, and death occurs in from one to six days, as the result of pulmonary consolidation. There are no symptoms accompanying the approach of death, except a gradual fail- ure of respiration and a peculiar sluggishness,' which is char- acteristic and probably dependent upon carbonic-acid poi- soning. The immediate cause of death can undoubtedly be attri- buted to the altered condition of the lungs, which present a state of simple vascular engorgement, without any apparent inflammatory condition either of the lung or pleura. In very young animals, the division of the vagi is followed by almost immediate death, but this is attributable rather to paralysis of the glottis and the ensuing suffocation than to pulmonary congestion, which requires time for its development. Effects upon the Lungs. — There have been many theories advanced to explain the effects of division of the pneumo- gastric nerves upon the lung tissue, and particularly to ex- plain why such an operative procedure should be followed by excessive pulmonary hypersemia, so as to cause the specific gravity of the lungs to exceed that of water. It seems to me that the theory, that the entrance of secretions or food into the lung through the paralyzed glottis (which can no longer spontaneously expel any foreign body) will explain the con- solidation of the lung as a direct result of irritation, is not sus- tained either by the pathology of the pulmonary lesion or by experiments where a canula has been placed in the larynx to prevent this cause of irritation. Bernard has explained it on the ground that traumatic emphysema of the lung is devel- oped from the labored inspiratory efforts made by the animal after the division of the vagi, thus creating a mechanical hcemorrhage which eventually consolidates the lung tissue. He sustains this theory by the fact that birds, whose lungs are fixed and immovable, and are therefore inexpansible, fail ' The convulsions which often accompany asphyxia are usually absent in these animals. EFFECTS OF SECTION OF PNEUMO GASTRIC. 251 to present this condition when the vagi are divided, although death is produced. To my mind, the most plausible explanation of the effects of this operation upon the lungs may be regarded as a purely mechanical one, dependent upon the impeded entrance of air through the larynx. During each inspiratory effort, the depression of the diaphragm and the elevation of the ribs tend to create a vacuum within the pleural and pericardial sacs, and thus favor the entrance of both air and blood into the thorax. So long as the entrance of either one remains unimpeded, the proper balance between the two is preserved, and neither too much air nor too much blood is sucked in with each inspiration ; but, when the air is prevented from enter- ing, an excess of blood flows into the lung with each inspira- tion, and, in the course of time, the lung is thus mechanically consolidated. Were the number of respirations not greatly decreased from the normal standard, the duration of life would probably be proportionally shortened, as the same effect would be produced in shorter time. The death of birds and some other animals, after section of the vagi, may possi- bly be explained on the ground of a too powerful impression upon the respiratory center. Effects upon the Heart. — In addition to the effects upon the lungs, division of the pneumogastric nerves is followed by a marked alteration of the action of the heart. The effects are somewhat similar to those which might result if the gov- ernor of a steam-engine were suddenly removed, and the piece of mechanism allowed to proceed without its control- ling influence. Thus the heart increases slightly in the rapid- ity of its pulsations, and the amount of cardiac pressure becomes slightly diminished, when one of the nerves is sev- ered ; but, when both are divided, the respiratory symptoms far outweigh those of the heart, but its action is still accel- erated and often irregular, since the inhibitory power of the nerves is destroyed. Effects upon the Digestive Tract. — The oesophageal branches of the vagus are the motor nerves, which control the 252 THE CRANIAL NERVES. peristaltic action of that tube (as is proven by the fact that division of the pneumogastric nerves of both sides causes complete paralysis), and also the means by which sensation is afforded to its mucous lining. In animals which have been subjected to division of the vagi, attempts to swallow food in any considerable quantities create a distention of the upper part of the oesophagus, and regurgitation by means of the mouth takes place without the food entering the stomach,' as was proven by Bernard, who made a gastric fistula in a dog before dividing the pneumogastrics, in order to decide this point. From what source the motor fibers which control the movements of the oesophagus are derived by the pneumogastric nerve is still a matter of doubt ; the root of the nerve itseK seems to possess some influence upon it, thus showing that it can not be traced to the nerves which communicate with it below the jugular foramen. The branches which are distributed to the liver by the pneumogastric nerves are probably, in some way, connected with the glycogenic function of that organ, since division of these nerves causes the liver to yield no traces of sugar after the animal succumbs, which is contrary to the result obtained after death in animals which have these nerves intact. When the nerves are divided in the living animal, and the end near- est to the brain is galvanized, an increase of sugar in the blood is thus artificially produced at any time during the life of the animal, and traces of the same may also be found in the urine. A similar hyper-secretion of sugar by the liver may be also noticed after the inhalation of irritating vapors or anaesthetics, probably through the influence of the vagi. The gastric branches of the pneumogastrics show a marked alteration in their power of control over that organ when the main nerve trunks are divided. The mucous lining of the stomach becomes at once pale, and the secretion of gastric juice apparently arrested, although a slight amount of se- cretion may return in a few days if the animal survive. The ' Physiologists are not agi'eed as to the seat of the reflex act of vomiting which fol- lows division of the vagi. CLINICAL RELATIONS OF PNEUMOQASTRIG. 253 sensations of hunger and thirst remain, but are sensibly di- minished. Absorption by the stomach is evidently delayed, but not arrested, as has been proven by the introduction of poisons into that organ. The intestinal branches of the vagi unquestionably con- trol the secretions of the canal, and section of the nerves has been shown to prevent the action of the most powerful cathartics, even in fatal doses, when administered immedi- ately before the vagi were divided. It is still a question whether the pneumogastric nerves influence the secretions of the intestinal canal directly, or through the sympathetic sys- tem by means of communicating filaments. If the latter be the case, those filaments of communication which control the stomach and oesophagus must be sought for high up in the cervical region. CLII^ICAL POII^TS PERTAINING TO THE PNEUMOGASTRIC NERVE. The physiological function of the separate branches of the pneumogastric, as mentioned in preceding pages, will assist you in appreciating the various manifestations of diseased conditions of the main trunk of the vagus, or of its individual branches. You can understand, from what has previously been said, that the effect of degeneration, section, or pressure upon this important nerve must vary with the seat of the lesion ; since those branches given off above the point where the nerve is impaired will manifest their usual powers, while those given off below that point wiU show symptoms of par- tial or complete paralysis. We can, therefore, study the effects of impairment of the pneumogastric nerve by considering the individual branches in their order from above downward, and recording the special types of disease which are liable to cre- ate symptoms referable to each branch. The pharyngeal branch contains both motor and sensory fibers ; hence injury to its structure will create both paralysis and anaesthesia, while simple irritation of its fibers will tend to create contraction or spasm of certain muscles to which its motor fibers are distributed. We thus see, in attacks of 254 THE CRANIAL NERVES. hysteria, the so-called "globus hystericus^''' a spasmodic affection of the pharynx, due to some irritation of the pneumogastric trunk or of the pharyngeal branches. We also occasionally meet true paralysis of this branch ; in which case, the act of deglutition is greatly impaired, and, if the disease is bilateral, swallowing is rendered almost an impossibility. The superior laryngeal branchy whose function is to sup- ply the mucous lining of the larynx with sensibility, ' becomes, under irritation, the cause of ''spasm of the glottis" and of ''whooping-cough." The former condition, called also '' stridulous Zar2/7^<7^Y^5" and "Kopp's asthma," is a disease peculiar to children, which tends toward asphyxia, but which is rarely if ever fatal. It usually occurs during the night, and seems to affect children who have been in apparent health. It is most common during the cold months ; is sometimes as- sociated with convulsions ; and is characterized by a sibilant character to the respiration, pallor, or turgidity of the coun- tenance, and a peculiar retraction of the head. In rare cases, this condition is met with in the adult, during attacks of hys- teria. It seems to be dependent, in children, upon dentition, digestive irritation, anaemia, rickets, etc. The experiments of Rosenthal seem to point to the superior laryngeal nerve as the exciting cause of the convulsive cough of "pertussis^^^ and also of that analogous cough often met with in hysterical subjects, since artificial stimulation of the nerve produced, with this observer, similar results. Whether the irritation of the nerve proceeds from the catarrhal in- flammation which exists in the respiratory passages, or irri- tation of some spinal or cerebral center, is not yet well deter- mined. The recurrent laryngeal branch is of great clinical impor- tance, since its peculiar course often makes it a guide to aneu- rism of the large blood-vessels by the peculiar symptoms which ' See page 232 of this volume. ^ The reader is referred to "A Treatise on Surgical Diagnosis" (Xew York, 1881), by the author, for all the points of diagnosis of this type of disease. CLimCAL RELATIONS OF PNEUMOGASTRIG. 255 it creates within the larynx.' The so-called "brassy cough" is, by some surgeons, considered as pathognomonic of press- ure upon or irritation of this branch, and strongly indicative of aneurism of the subclavian, carotids, the arteria innomi- nata, or of the left side of the arch of the aorta. This branch may be affected by central causes, as well as by peripheral pressure or irritation. As examples of the cen- tral causes of impairment of this nerve may be mentioned those cases of apoplexy, cerebral tumors, hysteria, diphthe- ria, typhoid fever, and reflex irritation from diseases of the uterus or genitals, where the larynx is markedly affected. The peripheral causes which more commonly affect the recur- rent laryngeal nerve, include catarrhal, tuberculous, and syphilitic inflammations of the larynx, traumatism, the press- ure of growing tumors, as aneurism, goitre, sarcoma, cancer, lymphatic tumors, tumors of the oesophagus, etc. The experiments of Bernard, Bischoff, and Waller ' (given in some detail in previous pages) will help to explain how a lesion, which excites laryngeal symptoms, may occasionally be situated away from the line of the pneumogastric nerve, since the spinal accessory nerve may be the seat of irritation or degeneration. They will also help to explain why the ef- fects of bilateral paralysis of the recurrent branch do not produce dyspnoea, at the same time that it causes the voice to be lost ; why the vocal cords are seen to be cadaveric and relaxed ; and why the act of coughing and the expulsion of laryngeal mucus is no longer possible. The pulmonary 'branches of the nerve are unquestionably concerned, to some extent, in the conditions associated with bronchial spasm, since asthma may be developed by mental influences acting upon the origin of the vagus. Moreover, we often see severe types of this disease produced by the press- ure of thoracic tumors upon the pneumogastric ; by the in- halation of substances possessing slight irritative qualities; by uterine irritation, acting as a cause of reflex action through the pneumogastric nerve ; and by fright, shock, exposure, ^ See page 264. 256 THE CRANIAL NERVES. etc. The symptoms of asthma are too well known to be hei< repeated. We have one other condition developed as the effect of pressure upon, or destruction of, the vagus, viz., paralysis of the pulmonary branches and the consequent paralytic condi- tion of the blood-vessels of the lung. It is to this condition that some authors attempt to refer the serous infiltration into the parenchyma of the lung which follows section of this nerve ; ' and we know, clinically, that a similar condition is sometimes produced by compression of the nerve by a tuber- culous or cancerous degeneration of the lymphatic glands, especially those situated near to the bifurcation of the trachea, and by aneurism of the thoracic vessels. The same condition has been observed after injuries to the organs of the chest, and from the section of some of the branches of the vagus, during an attempt to ligate the subclavian in its first portion or the arteria innominata. The cardiac branches seem to exert a more marked effect upon the heart when exposed to irritation than when actu- ally destroyed by degeneration or section. An artificial *' angina pectoris" may be produced by pressure upon the vagus in the neck (as performed by Czermak upon himself), and the heart's action may thus be almost entirely arrested. It may be stated, I think, that angina pectoris, sometimes called "cardiac neuralgia,"' is one of those neuroses of the heart which depend, to a large extent, upon changes of a secondary character in the terminal filaments of the vagus or the cardiac ganglia. The symptoms of this affection are very distressing to the patient, and often fatal. The attack usually begins with a sense of extreme constriction within the chest, which is fol- lowed by radiating pains of a very intense character, which ' For the different theories advanced to explain this effect, the reader is referred to page 250 of this volume. ^ I prefer to limit the term " angina pectoris " to those cases only where the exciting causes have resulted in defective heart power, and to apply the term " cardiac neuralgia " to those cases where the power of the heart is normal. This I consider to be the true pathological distinction. GARDIALGIA, BOULIMIA, POLYDIPSIA. 257 shoot down the arm or into the neck. The paroxysms pro- duce the most rapid exhaustion, and are not usually long continued. The various pathological conditions found to exist in this affection include an ossified state of the coro- nary vessels (thus interfering with the nutrition of the heart walls) ; cardiac hypertrophy (which is usually of that form called compensatory, since the cavities of the heart are gen- erally dilated) ; fatty degeneration of the heart ; valvular lesions (with their secondary changes in the size of the cavi- ties) ; and aneurism within the pericardial sac. The gastric branches of the vagus are associated with the conditions of gastrodynia (cardialgia), boulimia, polydipsia, nervous vomiting, and disorders of the secretory follicles of the organ, as well as its power of absorption. Gastrodynia is a paroxysmal attack of neuralgia of the sensory fibers of the stomach. It produces pain of the most intense character, which often compels the strongest subjects to writhe in agony, and to become bathed in a profuse perspiration, irre- spective of the temperature of the atmosphere. The face becomes bloodless, the limbs cold, the abdomen retracted, and the pulse small and irregular. The attacks are usually of short duration, and are most frequently terminated by eruc- tations and vomiting. This disease is met with in hysterical and anaemic subjects, in the course of diseases of the uterus and ovaries, in spinal and cerebral affections, and in certain dyscrasise. An abnormal condition of hunger, which is appeased by small quantities of food, but which returns at frequent inter- vals with an uncontrollable desire, often interrupting the hours of sleep, is produced by some disordered condition of the vagus, and is called "houlimia:' This affection is met with in hysterical patients, after prolonged fevers, in severe forms of nervous debility, in syphilis, insanity, and diabetes. By "polydipsia'' we mean an intolerable thirst, depend- ent upon an hypersesthesia of the nerve fibers of the mucous membrane of the stomach, pharynx, and mouth, and prob- 258 THE CRANIAL NEMVES. ably due to some abnormal state of the pneumogastric nerve. It is often an associate symptom with boulimia, and is pro- duced by the same general causes. The state of '''polyphagia^'' signifies a desire for excessive quantities of food. It is supposed to exist when the nerve fibers of the vagus distributed to the stomach are in a state of, anaesthesia, in contrast to the condition producing the tw( previous diseases. It has been found to accompany soften- ing of the medulla oblongata, compression of the roots of the vagus by an aneurismal tumor of the vertebral artery, atroph; of the vagi, neuromata of the vagi, and the morbid states oi epilepsy, insanity, and hysteria. The nervous vomiting which is clinically observed in con4 nection with pregnancy, chlorosis, hysteria, digestive disturb- ances, and gastrodynia, is not to be confounded with that of local diseases of the stomach or of the alimentary canal, since the symptom depends, purely and exclusively, upon some ab- normal condition of the nerves, rather than upon pathological changes in the stomach or intestine. True paralysis of the gastric branches of the vagus must, of necessity, arrest the peristaltic movement of that organ, and thus tend to favor the retention of food within its cavity. This may be the explanation of the enormous enlargement of the stomach found after chronic inflammatory processes of that organ, and also as a sequel to cholera, typhoid fever, and some other blood poisons. The stomach becomes en- larged in these conditions mainly by the weight of the retained food and the pressure of the gases formed by its decomposition. The intestinal and hepatic branches of the vagus are not well understood in their clinical phenomena, but the effects of section of the pneumogastric seem to point to some con- trolling influence of these fibers over the glycogenic function of the liver and the secretion of the intestinal juices. The effect of diseases of the peritonaeum, or of the abdominal viscera, upon the heart and respiration, is to be explained either as the direct result of irritation of these fibers, or as a THE SPINAL ACCESSORY NERVE. 259 reflex act through the sympathetic nerve upon the cardiac and respiratory centers, thus in turn affecting the heart and lungs through the vagus. THE SPINAL ACCESSORY, OR ELEVENTH CRANIAL NERVE. This nerve has a very extensive origin, since it derives its libers not only from the medulla oblongata, but also from the cervical portion of the spinal cord. The fibers which arise from the medulla compose what is called the "bulbar por- flon,^^m contrast to those which arise from the cervical region of the spinal cord, to which the name of '' spinal portion^'' is sometimes given. Such a distinction has an importance, dis- tinct from merely indicating the point of origin of the fibers composing the two portions of the nerve, as the functions of the two are different. If we trace the filaments of origin of the bulbar portion of the nerve, we can perceive that the fibers arise from the lat- eral columns of the medulla oblongata (its motor tract) and escape from its lower portion, beneath the fibers of the pneu- mogastric nerve. The spinal portion of the nerve can be traced between the anterior and the posterior roots of the first five cervical nerves, arising from between the roots of each nerve by a pair of filaments, with the exception of the last two, where the filament going to form the spinal accessory nerve is usually a single one. These several fibers unite as the nerve passes upward toward the cranium, thus causing the spinal portion of the nerve to gradually increase in size. In the cranium, the two parts join to form one nerve, which then escapes from the jugular foramen, in company with the pneumogastric and glosso-pharyngeal nerves and the jugular V ein. The inferior meningeal artery enters the cavity of the cranium through this foramen, and therefore bears a relation to the nerves and vein. The spinal accessory nerve receives filaments of communi- cation with other nerves, even before it escapes from the cavity of the cranium, since the spinal portion, on its way THE CRANIAL NERVES. upward to unite with the bulbar portion, is joined by fila- ments derived from the two upper cervical nerves while in" the spinal canal. After the nerve has emerged from the jugular foramen, it gives off a large branch to the pneumogastric nerve, and occa- sionally receives a filament from the pneumogastric in return ; Fig. 94. — Spinal accessory nerve. (Hirschfcld.) 1, trunk of the facial nerve ; 2, 2, glosso-pharyngeal nerve; 3, 3, pneumogastric; 4, 4, 4, trunk of the spinal accessory ; 5, sublingual nerve ; 6, superior cervical ganglion ; 7, 7, anastomosis of the first two cervical nerves ; 8, carotid branch of the sympa- thetic; 9, 10, 11, 12, 13, branches of the glosso-pharyngeal; 14, 15, branches of the facial; 16, otic ganglion; 17, auricular branch of the pneumogastric; \9>, anasto- mofdng branch from tJie spinal accessory to the pneumogastric ; 19, anastomosis of the first pair of cervical nerves with the sublingual ; 20, anastomosis of the spinal acces- sory with the second pair of cervical nerves ; 21, pharyngeal plexus ; 22, superior laryngeal nerve ; 23, external laryngeal nerve ; 24, middle cervical ganglion. while, in its course down the neck, it receives filaments of communication from the second, third, and fourth cervical nerves, in case these nerves do not communicate with the spinal portion within the spinal canal. After the nerve has sent its upper filament to the pneumo- DISTRIBUTION OF SPINAL ACCESSORY. 261 gastric, at tlie Jugular foramen, it may usually be perceived to divide into two branches — an internal and an external ; the former of which anastomoses directly with the trunk of the pneumogastric nerve, while the latter, called the "muscular branch," pierces the back part of the upper third of the sterno- mastoid muscle, and terminates on the anterior surface of the trapezius. The first, sometimes called the ''anastomotic Fig. 95. — Po,sif,i n c' of the muscles of Fig. 96. — Lateral view of the muscles of the larynx. (Sappey.) the larynx. (Sappcy.) Fig. 95. — 1, posterior crico-arytenoid muscle ; 2, 3, 4, different fasciculi of the arytenoid muscle ; 5, aryteno-epiglottidean muscle. Fig. 96. — 1, body of the hyoid bone; 2, vertical section of the thyroid cartilap^e ; 3, hori- zontal section of the thyroid cartilage turned downward to show the deep attach- ment of the crico-thyroid muscle ; 4, facet of articulation of the small cornu of the thyroid cartilage with the cricoid cartilage; 5, facet on the cricoid cartilage; 6, superior attachment of the crico-thyroid muscle ; 7, posterior crico-arytenoid mus- cle; 8, 10, arytenoid muscle; 9, thyro-arytenoid muscle; 11, aryteno-epiglottidean muscle; 12, middle thyro-hyoid ligament; 13, lateral thyro-hyoid ligament. branch," is now known to be the nerve which supplies the muscles of the larynx^ with the exception of the crico-thy- roid muscle,' since physiological experiment confirms this distribution. ^ The arytenoid muscle of the larynx is supplied by both the superior and recurrent laryngeal nerves, the latter of which carry most of the spinal accessory fibers, as is shown in Fig. 91 of this volume. It is also important to remember that the investiga- 19 262 THE CRANIAL NERVES. \ The second branch communicates with the second and third cervical nerves, before it pierces the sterno-mastoid muscle, and its filaments undoubtedly furnish motor power to that muscle and also to the trapezius. It is proven by ex- FiG. 97. — A diagram of the spinal accessory nerve. I, the accessory portion oi the nerve arising from the medulla oblongata; 2, the spinal portion of the nerve arising from the spinal cord (cervical region) ; 8, a filament arising from i\\e first and second cei'vical nerves and joining the spinal portion of the spinal accessory nerve, before passing through the foramen magnum; 4, the fora- men magnum, showing the spinal portion of the nerve entering the cranium ; 5, the jugular foramen, showing the spinal and accessory portions of the nerve conimuni- cating as they pass through it ; 6, the large filament going to the pneumogastric to supply the muscles of the larynx, and the S7nall filament returning to the trunk of the spinal accessory nerve ; 7, 8, 9, filaments of communication between the spinal accessory nerve and the third, fourth, and fifth cervical nerves ; 10, muscular branches to the ste)'no-c!eido-mccstoid muscle; 11, muscular branches to the trapezius muscle; 12, communicating filaments from the cervical plexus of nciTcs. periment, however, that section of the spinal accessory nerve does not produce total paralysis of these muscles ; and, from tions of Bernard and Bischoff have demonstrated the existence of other motor fibers to the larynx, irrespective of those of the spinal accessory, which seem to control the auto- matic rcspiratoj'y movements of the glottis. FITSCTIOJ^S OF SPINAL ACCESSORY NERVE. 263 this fact, it is conclusively proved that some other sources of nerve supply to these muscles exist, besides the spinal acces- sory filaments. A TABLE OF THE BRANCHES OF THE SPI:N^AL ACCESSORY KERVE.* Branches to tha pharyngeal plexus, Accessory or bulbar | Branches to the superior laryngeal nerve (and PORTION (by means ^ tlmB to i\\Q depressor nerve of the heart), of the sheath of the I Branches to the recurrent laryngeal nerve (thus 0. [ supplying the muscles of phonation). f Branch to the sfer?io-mas(oid muscle, j Branch to the trapezius muscle. f 1st cervical nevve, Communicating j 2d cervical nerve, BRANCHES TO ] od ccrvical nerve, l^ 4th cervical nerve. The spinal ac- cessory, or 11th crani- al NERVE. pneumogastric nerve) Spinal portion. { WJh fui^ctio:n's of the spin"al accessory kerve akd the EFFECTS or SECTION. The experiments of Bernard, to whose ingenuity much of our present knowledge of the function of the bulbar and spi- nal portions of this nerve is due, seem ^^ ^ ^ to warrant the conclusion that the bul- bar or medullary part of the nerve pos- sesses a direct control upon the mus- cles of the "pharynx and larynx^ but no effect whatever upon the sterno- mastoid and trapezius muscles. Gal- vanism of the spinal portion of the nerve seems to have a directly oppo- site effect, since the muscles of the pharynx and larynx were unaffected, and the two muscles of the neck to which the nerve is distributed were thrown into movement. It also ap- pears from the results of this great experimenter that the nerve is essen- tially motor in its function at its ori- gin from the medulla and spinal cord, but that it gains sen- sory fibers after it leaves the cavity of the cranium, by means ' Modified from a table in the " Essentials of Anatomy" (Darling and Ranney). Put- nam's Sons, New York, 1880. Fig. 98, — Glottis seen ivith the la- ryngoscope dxiring the emis- sion of high-pitched sounds. (Le Bon.) 1, 2, base of the tongue ; 3, 4, epiglottis ; 5, 6, pharynx ; 7, arytenoid cartilages ; 8, open- ing between the true vocal cords; 9, aryteno-epiglotti- dean folds ; 10, cartilage of Santorini : 11, cuneiform car- tilage; 12, superior vocal cords ; 13, inferior vocal cords. ^ 264 THE CRANIAL XERVES. of certain filaments of communication derived from the cer- vical nerves and the pneumogastric. This fact probably ex- plains why two points of communication should exist be- tween the spinal accessory and the pneumogastric nerves ; since, at one point, the sensory filaments of the pneumogas- tric were given to the spinal accessory, while, at the other point, the motor filaments of the spinal accessory were sent to the pneumogastric sheath for protection, until they could be distributed to the muscles of the larynx. Bernard and Bischoff have probably done more to clear up the disputed relation of the spinal accessory nerve to the mus- cles of the larynx, and thus to the acts of phonation and res- piration,' than any of the later investigators upon the physi- ology of the nervous system. When the spinal accessory nerve is drawn out from the meduUa and spinal cord of an animal, as can be done with little if any injury to the nerve, if the requisite care and skill be employed, the effect is at once manifested in the voice^ which becomes hoarse and unnatural, when the nerve of one side only is extracted, but entirely extinct when both nerves are thus treated. The act of deglu- tition is also somewhat affected, and the trapezius and sterno- mastoid muscles are paralyzed, but only to a partial extent. An interesting relation of the spinal accessory nerve to the action of the heart seems to be well shown by the experi- ments of Waller, who first called the attention of the profes- sion to the fact that extirpation of the roots of the spinal accessory nerve produced a modification in the effects of gal- vanism of the trunk of the pneumogastric nerve, provided that sufficient time (some two weeks) was allowed after the operation for the irritation so produced to subside. As has been mentioned in the previous lecture upon the pneumogas- tric nerve," galvanism of that nerve with a powerful current will arrest the action of the heart in a state of health, even if ^ The nerves concerned in the two acts of phonation and respiration are not to bo confounded, since it is probable that the pneumogastric nerve sends filaments of a motor character to the larynx, which are independent of the spinal accessory nerve, and which probably preside over the respiratory movements of the glottis, while the spinal accessory nerve controls pJionation. * See page 230 of this volume. fu:n'gtions of spinal accessory nerve. 265 applied on one side of the body. Now, Waller found that after the spinal accessory nerve of one side had been drawn out, and the animal allowed to recover the shock of the opera- tion, and to wait some days for all signs of irritation to sub- side, galvanism of the pneumogastric nerve of the same side no longer seemed to affect the action of the heart. The de- FiG. 99. — The spinal accessory nerve. (Sappey.) 1, large root of the fifth nerve ; 2, ganglion of Gasser ; 3, ophthalmic division of the fifth ; 4, superior maxillary division ; 5, inferior maxillary division ; 6, 10, lingual branch of the fifths containing the filaments of the chorda tympani ; Y, branch from the sub- lingual to the lingual branch of the fifth ; 8, chorda tympani ; 9, inferior dental nerve ; 10, terminal branches of the gustatory nerve ; 11, submaxillary ganglion ; 12, mylo-hyoid branch of the inferior dental nerve; 13, anterior belly of the digastric muscle; 14, section of the mylo-hyoid muscle; 15, 18, glosso-pharyngeal nerve; 16, ganglion of Andersch ; 17, branches from the glosso-pharyngeal to the stylo-glossus and the stylo-pharyngev^ muscles; 19, 19, pneumogastric; 20, 21, ganglia of the pneumogastric ; 22, 22, superior laryngeal nerve ; 23, spinal accessory ; 24, 25, 26, 27, 28, sublingual nerve and branches. pressor nerve of the lieart, which arises from both the supe- rior laryngeal and pneumogastric nerves, since it has two heads, must, therefore, be in some way connected with the 266 THE CRANIAL NERVES. spinal accessory nerve. It may, therefore, be stated mth as muclx positiveness as any physiological point can be laid down, that the communicating filament given off by the spi- nal accessory nerve to the pneumogastric controls the heart fibers as well as the muscles of phonation. The distribution of the spinal accessory nerve to only two of the muscles of the neck — the sterno-mastoid and the tra- pezius — would naturally suggest, to the inquiring mind, why these muscles should have been singled out as particularly associated with this nerve. Throughout this entire course of lectures I have frequently called your attention to the fact, which can not be too often repeated, that the distribution of nerves to muscles always denotes a purpose on the part of Nature, and a similarity of function in the muscles supplied by the same nerve, if we will but search for it. Now, we have already seen that the spinal accessory nerve is chiefly destined to control the muscles of phonation^ since other nerve fibers go to the larynx, which assist in moving the vocal cords during the opening of the glottis, previous to each in- spiratory act ; therefore, the spinal accessory nerve can not be said to be directly concerned with the respiratory func- tion. If we will study the attitude assumed by a vocalist in the act of singing (and it is in the singing act, rather than that of talking, that we see the mechanism of jDhonation best displayed, since it requires more of a muscular effort than the simple articulation of words), we shall perceive that the sterno-mastoid and the trapezius muscles are important fac- tors in the production of voice^ as they tend to fix the shoul- ders (that is, the scapulae and the clavicles) and also the upper part of the sternum. In all vocal efforts, the first act necessary to its performance is a full inspiratory effort, which can only be performed by first calling into play those muscles which render the upper portion of the chest and the bones of the shoulder immovable, so as to have a fixed point from which the true inspiratory muscles can act upon the ribs and their cartilages ; and it can, therefore, be understood why these muscles should properly be placed under the control of RELATION'S OF SPmAL ACCESSORY NERVE TO VOICE. 267 that nerve which also controls the muscles which regulate the position and tension of the vocal cords during the expira- tory effort, and thus causes the proper vibrations of these cords, and regulates the note which follows. In animals, where the muscular branch of the spinal acces- sory nerve has been severed, a difficulty in progression has been observed by Bernard, and a peculiar shortness of breath after violent exercise. The difficulty in locomotion is not present in man, on account of certain anatomical peculiarities which render the arm unnecessary for progressive motion, which is not the case with quadrupeds ; but the shortness of breath which has been observed would probably exist in a man after violent exercise, or when any demand for an exces- sively full inspiratory effort occurred, if the trapezius or the sterno-mastoid muscles were paralyzed. A theory advanced by Hilton,' as explanatory of the pe- culiarity of the course of the spinal accessory nerve, deserves mention, since it tends possibly to explain not only the irreg- rJar course of the nerve, but also the object of the communi- cation of the sub-occipital with the spinal accessory nerves within the spinal canal. According to this author, the spi- nal portion of this nerve becomes joined to the sub-occipi- tal before it enters the cranium, and, since that nerve is almost exclusively a motor nerve, what object could the spinal accessory, which is itself a motor nerve, have in send- ing additional filaments to the sub-occipital, unless it was for the purpose of sending fibers to the inferior oblique, the two posterior recti, and the complexus muscles of the neck? N^ow, when a motor impulse is sent out by means of the spinal accessory nerve, the effects reach those muscles first Avhich are nearest to its place of origin ; hence, the muscles of the sub-occipital region are caused to contract before the trapezius or the sterno-mastoid muscles, and, by so doing, the head is drawn backward before the latter muscles act, thus greatly assisting them to raise the thorax, as well as in ren- dering the head a fixed point during the inspiratory act. 1 "Rest and Pain," London, 1S72. 268 THE CRANIAL NERVES. CLINICAL POINTS PERTAINING TO THE SPINAL ACCESSORY NERYE. Like all motor nerves, the spinal accessory may exhibit the condition of spasm or paralysis in the parts supplied by it ; if subjected to some source of irritation, as in the tirst in- stance, or to some lesion which destroys its power of con- duction, as in the latter. The spasm dependent upon irrita- tion of this special nerve seems to be confined exclusively to the sterno-mastoid and trapezius muscles. They may be uni- lateral or bilateral, and the muscular contractions may be either of the tonic or clonic variety. Both of these types of spasm are met with in connection with reflex irritation originating in some of the remote vis- cera ; hence they are not infrequent in severe types of hysteri- cal affections. They may also be produced by diseases affect- ing the upper cervical vertebrae, by certain forced movements of the head, by exposure to cold and wet, and by local dis- eases of the brain and spinal cord. When we consider the intimate connection which this nerve has with the spinal cord, as well as the medulla oblongata and brain, we can better appreciate the difficulty which often arises in locating the exact seat of the irritation which is producing these spasmodic movements. There are reported cases to prove that tumors of the brain or spinal cord, softening of either of these re- gions, meningeal inflammation of the brain or cord, injuries to the skuU or upper cervical vertebrae, and caries, periostitis, and tumors of the upper cervical vertebrae, may all be excit- ing causes of this spasmodic action. Tonic Spasm of the Sterno-mastoid and Trapezius Mus- cles. — When the sterno-mastoid muscle is the seat of tonic spasm, the head is so drawn that the ear approaches the clavicle, the occiput the tip of the shoulder, and the chin isj so rotated that it points toward the opposite side. This con- dition is of longer or shorter duration, and often shows a marked tendency to become a permanent contracture. Dur- ing the early paroxysms, the patient can not rectify the dis- placement of the head by his own voluntary efforts, and pas- CLINICAL RELATIONS OF SPINAL ACCESSORY NERVE. 269 sive motion is strongly resisted. The early periods of the paroxysm are often accompanied by sharp pains. When the disease has become chronic, the deformity of the neck is as- sociated with n^ permanent curvature of the cermcal mrtel)rce and a corresponding curve of a compensatory character in the dorsal and lumbar regions. A rare case of bilateral tonic spasm of the stemo-mastoid muscles is reported by Duchenne, in which the chin was approximated to the breast. The trapezius muscle may also be the seat of tonic spasm. In this case, the head is inclined toward the affected side, the occiput is drawn toward the shoulder, the shoulder itself is raised, and the scapula is drawn inward. The chin is not rotated toward the unaffected side, as in the case of the sterno-mastoid muscle. All attempts to bring the head into its proper relation to the trunk create a rigidity and sensi- tiveness over the region of the trapezius. Clonic Spasm of the Sterno-mastoid and Trapezius Mus- cles. — This variety of spasm, which is dependent upon the same general list of causes as the tonic form, may be uni- lateral or bilateral. Either of the muscles supplied by the spinal accessory may be affected alone, or the sterno-mastoid and trapezius may contract alternately. If the spasm be con- fined to one muscle and of the unilateral type, the deflection of the head will be the same as in the tonic spasm, except that the duration of the contraction will be for a shorter period, and of a convulsive variety ; while, if the two muscles of one side contract alternately, the attitude of the head will be constantly changing from the condition due to contraction of the one to that produced by the other. When the sterno- mastoid muscles of both sides act simultaneously in a spas- modic contraction, a peculiar '' nodding movement" is per- ceived. You can understand how all forms of combina- tions can be made between the two muscles of either side, and a proportionate variety of spasmodic attitudes will be the result. All of these contractions occur, for the most part, in paroxysms^ often lasting for a day, and not infre- quently coming on with such violence and frightful vehe- 270 THE CRANIAL NERVES. mence that the head is tossed to and fro with great force, making the life of the patient miserable. In some instances, the spasm is almost continuous. Sleep, however, usually brings rest, though this is often prevented or delayed. In unilateral clonic spasm of the sterno-mastoid muscle, the adjacent muscles of the face, jaw, and arm are occasional- ly thrown into simultaneous action. The scaleni muscles are also sometimes brought into active play, and their forcible compression of the brachial plexus of nerve and the veins of the neck has been known to result in stiffness, anaes- thesia, and oedema of the arm, after such an attack had sub- sided. The nodding movement produced by the bilateral clonic spasm of the sterno-mastoid muscles is sometimes called the *' salaam convulsion of Newnham." It is rarely seen in adults, but in children it is not infrequent. Should it occur during dentition, the spasm may be associated with convulsive movements of the facial muscles, with strabismus, and even with general convulsions and a loss of consciousness. Bi- lateral spasm of the muscles supplied by the spinal accessory nerve has been known to terminate in epilepsy, insanity, and paralysis ; and, when the various causes of the condition are reviewed, this will appear but the natural sequence of the further progress of some of the diseases mentioned. Should reflex irritation, as in dentition, worms, hysteria, etc., exist, or the spasm be dependent upon rheumatic origin, exposure to cold or dampness, traumatism, caries, and other curable conditions, the results will be arrested when the exciting- cause has been removed. Paralysis of the Sterno-mastoid and Trapezius Mus- cles. — These muscles may be affected with a total arrest of their nerve power by lesions of the motor columns of the spinal cord, resulting in progressive muscular atrophy ; by fracture of the cervical vertebrae ; diseases of the vertebrae near the skull and also of the cranial bones ; injuries to the nerve, such as cuts, stabs, gunshot wounds of the neck ; and compression of the nerve from peripheral causes, as in the CLINICAL RELATIONS OF SPINAL ACCESSORY NERVE. 271 case of tumors of the neck, swelling of the lymphatic glands of the neck, abscesses, neuromata, etc. The sterno-mastoid or the trapezius may be paralyzed in- dependently of the other, or they may both be affected si- multaneously, according as the cause affects the entire nerve or only some individual branch. The paralysis may, in some instances, be bilateral, provided the exciting cause be central and involve the parts in the median line, or so extensive as to press upon the trunks of both spinal accessory nerves. A case of bilateral paralysis following progressive muscular atrophy of the muscles of the neck is reported by Rosenthal, where the patient was obliged to support the head by a collar made of pasteboard ; but this was rather the consequence of the general atrojDhy of the muscles than the effect of the pa- ralysis of the two muscles supplied by the spinal accessory. In unilateral 'paralysis of the sterno-mastoid muscle^ the voluntary rotation of the head toward the unaffected side is performed with difficulty ; the chin is turned toward the af- fected side, on account of the unopposed action of the healthy muscle ; the chin is also slightly elevated, and the paralyzed muscle does not stand out vdth equal prominence with its fellow, when the chin is supported by the hand of the physi- cian, and direction is given to the patient to try and depress the chin toward the chest. If this unilateral paralysis be long continued, the contracture of the healthy muscles pro- duces the condition of '' torticollis." When a bilateral paralysis of the sterno-mastoid muscles is developed, the head is held straight, and its rotation, es- pecially with the chin elevated, is performed with extreme difficulty. The neck appears thin, and the lateral aspect of that region is markedly flattened, since the normal prominence of the sterno-mastoid muscle is wanting. The same test, as mentioned above, when the chin is supported by the hand of the physician, shows a great loss of power in attempting to flex the head upon the chest. The effects of unilateral paralysis of the trapezius mus- cle are most marked in the region of the scapula. This bone 272 THE CRANIAL NERVES. appears to be drawn downward and forward ; its inferior angle lies closer to the vertebral column than that of its fellow, and its upper part is more widely separated from the vertebrae. The clavicle is caused to stand off from the chest, on account of the acromion being drawn downward and forward by the weight of the upper extremity and the pectoral and the leva- tor anguli scapulae muscles ; hence, the supra- clavicular fossa is apparently enlarged, in comparison with the healthy side. It is to be remembered, however, by you that the trapezius, unlike many others in the body, often manifests paralysis in portions of the muscle ; so that the symptoms of this type of unilateral paralysis admit of many modifications, in accord- ance with the extent and limits of the disease. Thus, the position of the scapula will vary with the paralysis of the upper, middle, or lower fibers of the muscle ; the power of elevation of the arm will be greatly impaked if the upper fibers are paralyzed ; while the approximation of the scapula to the vertebral column is very much impaired when the middle fibers are alone involved. When the trapezei muscles are affected with bilateral paralysis^ in addition to the symptoms described, which wall now be perceived upon both sides, the hacJc will appear broader and more arched^ since the scapulae are lowered and drawn outward, while they are also more prominent. Some difficulty may also be experienced in maintaining the head in an upright position, since it naturally tends to sink toward the chest. THE HYPO-GLOSSAL, OR TWELFTH CRANIAL NERVE. This nerve is sometimes called the sublingual nerve^ thus using a Latin rather than Greek term to express the same idea, viz., that the nerve passes underneath the tongue. It is the last of the cranial nerves, and is intimately associated with all those movements in which the tongue takes an important part, such as the acts of talking, singing, mastication, and deglutition. The point of external origin of this nerve is a THE HYPO-GLOSSAL, OR TWELFTH NERVE. 273 groove between the olivary body of the medulla oblongata and the anterior pyramid^ below the point of escape of the ninth, tenth, and eleventh nerves. Its deep fibers can be traced to a nucleus in the floor of the fourth ventricle, and it is probable that some of them decussate in the median line of the floor of that cavity, thus passing to the opposite side of the medulla. The nerve escapes from the cavity of the cranium by the anterior condyloid foramen. Fig. 100. — Distribution of the hypo-glossal nerve. (Sappey.) 1, root of the fifth nerve; 2, ganglion of Gasser ; 3, 4, 5, 6, 7, 9, 10, 12, branches and anastomoses of the fifth nerve ; 11, submaxillary ganglion; 13, anterior belly of the digastric muscle ; 14, section of the mylo-hyoid muscle ; 15, glosso-pharyngeal nerve ; 16, ganglion of Andersch ; 17, 18, branches of the glosso-pharyngeal nerve; 19, 19, pneumogastric ; 20,21, ganglia of the pneumogastrie ; 22, 22, superior laryngeal branch of the pneumogastric ; 23, spinal accessory nerve ; 24, hypo-glossal nerve ; 25, dcsccndens noni ; 26, ihyro-hyoid branch ; 27, terminal branches ; 28, two branches^ one to iJie gcnio-hyo-glossus and the other to the genio-hyoid miAscle. After the nerve escapes from the cranium, it gives a fila- ment of communication to the sympathetic nerve, which joins 274: THE CRANIAL NERVES. the superior cervical ganglion ; another to the jpneumo gastric nerve; two or three branches to the upper cervical nerves; Fig. 101. — Anastomotic loop formed by the descending branch of the hypo-gloi^sal and the internal descending branch of the cervical plexus. (After Hirschfeld.) 1, lingual nerve passing transversely upon the hyo-glossus muscle ; 2, 2, trunk of the pneumogastric ; 3, superior laryngeal nerve ; 4, external laryngeal nerve ; 5, external branch of the spinal accessory supplying the stcrno-mastoid and trapezius ; 6, ante- rior branch of the second pair of cervical nerves ; 7, anterior branch of the third pair; 8, anterior branch of the fourth pair; 9, origin of the phrenic; 10, origin of the subclavian nerve; 11, origin of the anterior thoracic nerves of the brachial plexus; 12, middle portion of the trunk of the hypo-glossal; 13, desccndens noni ; 14, internal descending branch of the cervical plexus, forming, with the preceding, a loop with its convexity directed downward ; 15, inferior branch from this loop, sup- plying the sterno-thyroid muscle ; 1 6, superior branch distributed to the sterno-hyoid muscle; 17, another branch still higher up, and distributed to the same muscle; 18, middle branches from the loop; 19, filament extending as far as the lower ex- tremity of the sterno-thyroid ; 20, branch given off by the hypo-glossal to the thyro- hyoid ; 21, branches of anastomosis between the hypo glossal and lingual; 22, ter- minal portion of the trunk of the hypo-glossal. and, finally, a communicating branch to the gustatory 'branch of t\ie fifth nerve. DISTRIBUTION^ OF HYPO-GLOSSAL NERVE. 275 Fig, 102. — A diagram of the hypo-glossal and its branches. 1, trunk of hypo-glossal werw, escaping from the medulla oblongata; 2, anterior condyloid foramen ; 3, filaments of communication to i\\Q pneumogastric nerve ; 4, filaments of communication to the superior cervical ganglion of the sympathetic system ; 5, fila- ments of communication to the first and second spinal nerves of the cervical region ; 6, the dcscendens noni nerve, forming a loop with the comm.unicans noni nerve (19) and giving off muscular branches from the loop ; V, muscular filaments to the thyro- hyoid muscle ; 8, muscular filament to the geniohyoid muscle ; 9, muscular fila- ment to the genio-hyo-glossus muscle ; 10, muscular filament to the hyo-glossus muscle ; 11, muscular filament to the stylo-glossus muscle; 12, the occipital artery, around which the hypo-glossal nerve winds, before reaching the tongue ; 13, a branch of the communicans noni nerve, derived from the second cervical nerve ; 14, a branch of the communicans wowi nerve, derived from the third cervical nerve ; 15, a muscular branch to the omo-hyoid muscle (anterior belly); 16, a muscular branch to the sterno- hyoid muscle; IV, a muscular branch to the sterna-thyroid va\xsc\Q \ 18, a muscular branch to the omo-hyoid (posterior belly) ; 19, the commtmicans noni nerve, joining the descendetis noni nerve to form a loop. 276 THE CRANIAL NERVES. Its first branch of distribution is named the descendens noni (the descending of the ninth nerve), so called since this nerve was classed by Willis as the ninth. This branch passes down the neck to supply the stemo-hyoid, sterno- thyroid, and omo-hyoid muscles, and then joins the com- municans noni nerve (a branch of the cervical plexus), to form a loop, from which terminal filaments are given off. The other branches of the nerve are distributed to the thyro- hyoid muscle (which usually has a separate filament of its own), the stylo-glossus, the hyo-glossus, genio-hyoid, genio- hyo-glossus, and the intrinsic muscles of the tongue. It will thus be seen that the hypo-glossal nerve is the motor nerve of all the muscles which tend to depress the larynx and the hyoid hone^ after they have been raised during the second stage of the act of deglutition (the muscles of the infra-hyoid region), also to one of the supra-hyoid region, the genio-hy- oid, and to most of the muscles which act upon the tongue. In the preceding diagrammatic figur^, the branches of the hypo-glossal nerve are shown, and the general course of the nerve is made more clear than can be done by a verbal de- scription. TABLE OF THE BRANCHES OF THE HYPO-GLOSSAL NERVE.* f To the ganglion of the trunk of the pncu- mogastric nerve, Branc\es of ' '^^ *^^ superior cervical ganglion of the mmunLatdn ^ ^ Sympathetic, To the loop between the first and second cervical nervj s, , To the gustatory nei've. "" Descendens noni nerve, To thyro-hyoid nerve, To genio-hyoid muscle, distHb^Z < To stylo-glossus muscle, To hyo-glossus muscle, To genio-hyo-glossu8 muscle. To the intrinsic muscles of the tongue. THE HYPO-GLOSSAL, ORTWELFTHCRA- -{ NIAL NERVE. communication. Branches of FUNCTIONS OF THE HYPO-GLOSSAL NERVE. The fact that the hypo-glossal nerve arises from the motor portion of the spinal cord (when taken in connection with the 1 Copied from the " Essentials of Anatomy " (Darling and Ranney). Putnam's Sons, New York, 1880. FUNCTIONS OF THE HYPO-GLOSSAL NERVE. 277 absence of any ganglionic enlargement upon the trunk of tlie nerve) would seem to indicate that the function of the hypo- glossal is essentially motor ; and such a conclusion is sus- tained by the experiments of Longet, who found the nerve incapable of transmitting any sensory impressions when the roots were subjected to irritation. Mayo and Magendie, however, first proved that the nerve possessed sensory filaments, after it had escaped from the cavity of the cranium, which results have since been confirmed by most of the later physiologists. We can easily explain this acquired power of sensibility which the nerve exhibits, by the branches of communication which it receives from the pneumogastric, the cervical nerves, and the gustatory branch of the fifth nerve ; so that there is little, if any, reason to doubt that the original fibers of the nerve itself are purely motor in function. In connection with the glosso-pharyngeal nerve, I entered into a somewhat extended discussion of the mechanism of the act of deglutition ; ' and the same subject might, with equal propriety, be again repeated in connection with the hypoglos- sal nerve, since both are intimately associated with those complex movements. It will suffice, however, to again call attention to the fact, that movements of the tongue were of the greatest importance in swallowing, since that organ not only conveyed the bolus to the back portion of the mouth, and, when liquids were to be swallowed, helped to form a tube through which a suction force could be exerted, but also assisted in the prevention of food from entering the cavity of the larynx. CLINICAL POINTS PERTAINING TO THE HYPO-GLOSSAL NERVE. When this nerve is divided in animals, the sense of taste remains and the tongue retains its normal sensitiveness ; but the power of movement is utterly destroyed if the nerves of both sides are simultaneously cut. As a natural consequence, the first stage of the act of deglutition is materially embar- go ^ See page 226 of this volume. 278 THE CRANIAL NERVES. rassed, and the second stage is liable to be associated with the entrance of fluid, if swallowed, into the cavity of the larynx. When, in the human subject, this nerve is impaired, either as a special type of paralysis or during an attack of hemi- plegia, the power of protrusion of the tongue from the mouth in a straight line is lost, and that member becomes de- flected toward the side which is paralyzed, since the genio- hyo-glossus muscle is unopposed. A disease of rather rare occurrence, in which the hypo-glossal nerves of both sides are paralyzed, and, in addition, the orbicular muscle of the mouth, and, not infrequently, the intrinsic muscles of the larynx, is described by Duchenne ; ' and, since his article, it has been Fig. 103. — Glosao-lahio-laryngeal paralysis. (After Hammond.) written upon by most of the later authors under the names of glosso-labio-laryngeal paralysis, glossoplegia, etc. In this type of disease the tongue lies motionless and trembling in the De I'electrisation localia^e," Paris, 1861. BUCHENN-E'S DISEASE. 279 floor of the mouth, if all power of motion be paralyzed ; but, if paresis only exist, it can be imperfectly protruded with difiiculty, and is tremblingly and slowly retracted. If one side be affected, the sound side becomes full and promi- nent, in comparison with the affected side, when called into action. The peculiar trembling character of the move- ment of the tongue in bilateral paresis is observed in every motion which the patient attempts to perform with that or- gan, and all the motions are slowly and imperfectly accom- plished. The most important effects of the paralytic state of the muscles are shown in attempts at mastication and speech. The food is no longer properly placed between the teeth ; is with great difiiculty carried to the back part of the mouth ; and frequently regurgitates into the mouth, when attempts are made to swallow. The saliva is secreted in large quanti- ties, and is swallowed with extreme difiiculty, so that the patient is constantly obliged to expectorate. Fig. 104. — Glosso-labio-laryngeal paralysis. (After Hammond.) The disturbances of speech may present themselves with varying degrees of intensity. In those cases where the tongue is affected upon one side only (and a state of paresis exists, rather than that of complete paralysis of motion), only those sounds which require the aid of the tongue to be pronounced 280 THE CRANIAL NERVES. are indistinctly and incompletely articulated. These letters are 5, sch^ Z, e^ ^, and, at a later period, ^, ^, r, etc. When the paralysis is bilateral, and the tongue has under- gone atrophy, the speech becomes exceedingly indistinct, muttering and inarticulate, so that the patient can hardly express himself in sounds that can be understood by those in constant communication with him. The act of singing is always affected in even the mild forms of lingual paralysis ; and the falsetto notes are particularly affected, since the tongue plays an important part in so directing the sound as to give it its proper timbre. The effects of lingual paralysis must not be confounded with spasm of the lingual muscles (the act of stuttering), or, on the other hand, with dumbness and aphonia. In some cases of Duchenne's disease, the lips are not af- fected ; while, in others, the laryngeal and pharyngeal mus- cles are not impaired to a sufficient degree to cause any serious impediment to their normal functions. We can the better understand why all possible varieties and degrees of paralysis may exist in this disease when we consider that, in order to account for all the symptoms present in a fully developed case, the facial, spinal accessory, pneumogastric, and Jiypo-glossal nerves must be simultaneously diseased, or subjected to extreme pressure. Should the facial nerve escape, the lips and face will preserve their normal power; if the spinal accessory nerve be unimpaired, the larynx may escape, provided that the pneumogastric nerve remain intact below the point of communication between these two nerves ; if the hypo-glossal nerve be normal, the symptoms referable to the tongue would not be detected. The essential lesion of this disease seems to consist of a degeneration of the medulla oblongata and the upper portion of the spinal cord ; hence the nuclei of origin of the facial, spinal accessory, pneumo- gastric, and hypo-glossal nerves are liable to be involved to a greater or less extent simultaneously. Whether the view of Leyden, that the condition is one of myelitis, will be sus- tained, is still uncertain, but that the condition closely re- GLOSSO-LABIO-LARYNGEAL PARALYSIS. 281 sembles tliat which creates the spinal paralysis of the infant and adult seems positive. The previous existence of the early manifestations of syph- ilis and the probable activity of the disease in the system may account for the lesion in some cases, while in others the rheumatic diathesis, mental anxiety, and excessive mental application, ' seem to have acted as exciting causes. The general paralysis of the insane often first manifests itself in a peculiar weakness of the tongue and lips. The tremor of paralytic dementia probably first makes its appearance in the facial and lingual muscles. It consists in non-rhythmical contractions of small muscles or of fasciculi of muscles, which are either present in the quiescent state of the features, or are excited by emotion or by the performance of a voluntary movement, as showing the tongue or teeth. Sometimes innumerable fine, fibrillary tremors cover the face, while, in some cases, the movements are coarser, and irregular enough to merit the term choreic. The tongue exhibits both sets of tremors — the very fine fibrillary ones and the large choreic oscillations. There is, also, though usually at a later stage, some shriveling or atrophy of the tongue. I quote from a late article of Professor E. C. Seguin," as follows : ''The hands are tremulous, usually in a fine, semi-rhyth- mical way. This trembling is sometimes scarcely visible, but is perceptible as a delicate parchment-like fremitus on holding up the patient's extended fingers between ours. In the lower extremities the tremulousness is not apparent. ''The speech is affected as a result of this tremor, and as the result of a certain want of coordination in the muscles of articulation. Words are quickly spoken, with some syllables omitted or blurred, or with a terminal syllable left off. The articulate sounds which are produced are heard as vibratory or tremulous, and the speech seems thick. Patients semi-un- consciously avoid long or difficult words in conversation, and ' Such cases as these are reported in the admirable description of this complicated affection by my colleague and friend Professor W. A. Hammond: "Treatise on the Diseases of the Nervous System." New York: D. Appleton & Co., 18*76. 2 "Med. Record," 1881. THE CRANIAL NERVES. Fig. 105. — A diagram of the motor points of the face, showing the position of tlie electrodes during electrization of special miiscles and nerves. Ilie anode is supposed to be placed in the mastoid fossa, and the cathode upon (he part indicated in the diagram. 1, m. orbicularis palpebrarum ; 2, m. pyramidalis nasi ; 3, m. lev. lab. sup. et nasi ; 4, m. ley. lab. sup. propr. ; 5, 6, m. dilator naris ; 1, m. zygomatic major ; 8, m. orbicularis oris; 9, n. branch for levator menti; 10, m. levator menti ; 11, m. quadratus menti; 12, m. triangularis menti; 13, nerves — subcutaneous of neck; 14, m. sterno-hyoid ; 15. m. omo-hyoid ; 16, m. sterno-thyroid ; 11, n. branch for platysma ; 18, m. sterno- hyoid ; 19, m. omo-hyoid; 20, 21, nerves to pectoral muscles; 22, m. occipito- frontalis (ant. belly) ; 23, m. occipito-f rontalis (post, belly) ; 24, m. retrahens and attollens aurem; 25, nerve — facial; 26, m. stylo-hyoid; 27, m. digastric; 28, m. splenius capitis ; 29, nerve— external branch of spinal accessory ; 30, m. sterno- mastoid; 31, m. sterno-mastoid ; 32, m. levator anguli scapulae; 33, nerve — phrenic; 34, nerve — posterior thoracic ; 35, m. serratus magnus ; 36, nerves of the axil- lary space. even seek roundabout ways of expressing their meaning by- shorter words. Besides this vibratory tremulousness in SPASM AND PARALYSIS OF THE TONGUE. 283 articulation, there is an imperfection in tlie pronunciation of words — long words especially. Remedy is pronounced 'remdy'; constitution, ' constution '; infallibility, 'infallaby.' The last syllable may be badly sounded, or even omitted. I have known this characteristic speech to be the only well- marked symptom, and to be followed by dementia, exaltation, etc. Occasionally, a patient comes to us complaining of this defective articulation." Interference with the free action of the hypo-glossal nerve, when not associated with a simultaneous affection of other nerves, may result in the production of spasm or paralysis. Spasm of the tongue may be perceived in connection with the spasmodic diseases, such as chorea, epilepsy, and hys- teria ; also, as a result of slight compression or irritation of the hypoglossal nerve from meningeal exudation; while a fibrillary tremor of the tongue is observed in progressive muscular atrophy. In severe types of facial spasm, and in those forms of disease where the lingual nerve is the seat of a neuralgic affection, the hypo-glossal nerve may create a type of clonic spasm. Paralysis of the tongue is usually unilateral, and may be the result of cerebral haemorrhage, softening, embolism, tumors, or the progressive paralysis of the insane. In rare cases, this condition has occurred from injury done to the nerve from the removal of a tumor of the tongue itself ; while instances have been reported where the nerve was impaired by pressure upon its trunk, either at the base of the brain, or at its point of escape from the anterior condyloid foramen. THE SPINAL CORD. ITS ANATOMICAL CONSTRUCTION, FUNCTIONS, AND CLINICAL BEARINGS. THE spi:n"al coed. In the previous lectures of this winter's course, we have considered the anatomy of the brain, and the nerves which arise from it. We have noted the general points in the construction of each, and discussed the clinical bearings of the individual parts which have successively demanded our attention. It now remains for us to begin the study of the other great half of our nervous organism, viz., the spinal cord, and the nerves which are connected with it. I shall follow the same general plan, in treating of the spinal cord and its nerves, as I have pursued in the early part of the course, viz., to give such points only in the descriptive portion as shall conduce to a full comprehension of the clinical bearings of the regions under discussion, and to im- press upon you constantly such suggestions of practical value as the theme recalls to my mind. Should the anatomical de- scription of the separate parts seem, at any time^,^ incomplete, I trust to omit nothing that can not be easily supplied from the best text-books upon anatomy ; but I shall fall short of my proposed task if I fail to incorporate such points as shall assist you in comprehending many of the new terms found scattered throughout the more advanced treatises upon the anatomy and diseases of the nervous system. The spinal cord comprises that part of our central nervous system which is contained within the canal of the vertebral column. It may be said to begin at the point where the 288 THE SPINAL CORD. fibers of the anterior pyramids of tlie medualla oblongata be- gin to decussate (which point corresponds to the upper border of the atlas), and it terminates at the lower border of the first lumbar vertebra. It may then be stated that the entire length of the spinal cord varies from fifteen to eighteen inches (since it depends somewhat upon the height of the in- FiG. 106. — Cervical por- tion of the spinal cord. (Hirschfcld.) Fig. 107. — Dorsal por- tion of the spinal cord. (Hirschfeld.) Fio. 108. — Inferior por- tion of the spinal cord, and Cauda equina. (Hirschfeld.) 1, antero-inferior wall of the fourth ventricle ; 2, superior peduncle of the cerebellum ; 3, middle peduncle of the cerebellum ; 4, inferior peduncle of the cerebellum ; 5, in- ferior portion of the posterior median columns of the cord ; 6, glosso-pharyngeal nerve ; 7, pneumogastric ; 8, spinal accessory nerve ; 9, 9, 9, 9, dentated ligament ; 10, 10, 10, 10, posterior roots of the spinal nerves ; 11, 11, 11, 11, posterior lateral groove; 12, 12, 12, VI, ganglia of the posterior roots of the nerves ; 13, IS.aniei-ior roots of the nerves ; 14, division of the nei'ves into two branches ; 15, lower ex- tremity of the cord; 16, 16, coccygeal ligament; 17, 17, cauda equina; I — VIII, cervical nerves ; I, II, III, IV — XII, dorsal nerves ; I, II — V, lumbar ncj-vcs ; 1 — V, sacral nerves. dividual), and that it does not extend throughout the entire length of the spinal canal. Its upper end is continuous with CERVICAL AND LUMBAR ENLARGEMENTS. 289 the lower part of the medulla oblongata (which, in my opin- ion, seems more properly a part of the cord than of the brain), while its lower end terminates in a slender filament, called the *'filiim terminale," which descends for a short distance into the central ligament. THE GENERAL CONSTRUCTION OF THE CORD. The spinal cord is not of the same size or general shape in all portions of its length, since it tapers gradually toward its lower extremity, with the exception of presenting two local enlargements, caUed the '' cermcaV^ and "lumbar^' enlarge- ments.^ The former of these extends from the third cervical to the first dorsal vertebra, and is widest from side to side ; Fig. 109. — Transverse section of the spinal cord at the origin of the fifth pair '^ of cervical nerves. (Stilling.) In this fifTure, the white substance of the cord is represented in black, to show more clearly the limits of the gray matter: 1, 1, antero-lateral columns; 2, 2, posterior white columns ; 3, anterior median fissure ; 4, posterior median fissure ; 5, white commissure ; 6, gray commissure ; 7, central canal ; 8, 9, anterior comua of gray matter; 10, 10, group of large multipolar cells ; 11, 11, 11, anterior roots of the spinal nerves; 12, posterior cornua of gray matter; 13, posterior roots of the spinal nerves. while the latter extends from the lower part of the eleventh dorsal to the lower border of the twelfth dorsal vertebra, and ' These enlargements correspond to the points of origin of the main nerves of the upper and lower extremities. 2 The line designated by Gubler. See page 183. 290 THE SPINAL CORD. is widest from before backward. When viewed exteriorly, the cord presents five fissures and four columns^ which are less distinct than the convolutions of the cerebrum ; and, on section made transversely across its substance, two general subdivisions can be made out by the naked eye, the white and the gray portions. When we come to discuss the clinical points pertaining to spinal localization, in case of disease, you will then realize that the further subdivisions of the spinal cord, which I shall impress upon your memories, are not based alone upon the results of enthusiastic microscopy, but are the grand evidences of a progress in this direction which the earlier anatomists had not dreamed of, and which are the foundation, I sincerely believe, of accurate and posi- tive diagnosis of spinal lesions at no distant date. The general exterior of the spinal cord is incompletely divided into two symmetrical lateral halves^ by the so-called ''antero-median fissure" and the " postero-median fissure," which do not cut the cord entirely in half, since a transverse commissure exists, called the '-^commissure of the spinal cord.^^ Now, this point is worthy of your careful attention, since it indicates a clinical fact, viz., that lesions of one lateral half of the cord produce symptoms in a lateral half of the body. Each lateral half of the cord has three fissures of its own : the " antero-lateral fissure," which corresponds to the points of escape of the anterior roots of the spinal nerves ; the *' pos- tero-lateral fissure," which corresponds to the points of at- tachment of the posterior roots of the spinal nerves ; and the ''postero-intermediary fissure,"' which is situated on the outer side of the postero-median fissure, which helps to di- vide the cord into its two lateral halves. The first two of these are mere traces upon the surface of the cord, while the last is most apparent in the cervical region. As demarcated by the fissures named above, the spinal cord presents four subdivisions of its exterior surface, called respectively the ''anterior," "lateral," ''posterior," and ^ Described by Sappey, Hirechfeld, and others. FISSURES AND COLUMNS OF THE CORD. 291 " postero-median" columns.' These are, however, of less im- portance, from a clinical standpoint, than the columns named after certain special investigators in this line of science; f^^i- .y,^^,: Fig. 110. — Transverse section of the spinal cord of a child six months old, at the middle of the lumbar enlargement^ treated with potassio-cldoride of gold and nitrate of uranium ; magnified 20 diameters. By means of these reagents, the direction of the fibers in the gray substance is rendered unumally distinct. (Gerlach.) «, anterior columns ; 6, posterior columns ; c, lateral columns ; d, anterior roots ; e, poste- rior roots ; /, anterior white commissure, in communication with the fasciculi of the anterior cornua and the anterior columns ; g, central canal with its epithelium ; Ji, surrounding connective substance of the central canal ; i, transverse fasciculi of the gray commissure in front ol" the central canal ; k, transverse fasciculi of the gray commissure behind the central canal ; I, transverse section of the two central veins ; m, anterior cornua ; n, great lateral cellular layer of the anterior cornua ; o, lesser anterior cellular layer; p, smallest median cellular layer; q, posterior cornua; r, ascending fasciculi in the posterior cornua ; s, substantia gelatinosa. which can better be demonstrated by a reference to the cuts showing the transverse section of the spinal cord.' The spinal cord gives off thirty-one pairs of nerves^ called ^ Some anatomists include the lateral with the anterior column, under the name of the " antero-lateral column," thus taking in about two thirds of the entire lateral half of the cord. ^ See cut on page 298 of this volume, and colored plate (after Hammond), 292 THE SPINAL CORD. ''spinal nerves," in contradistinction to those of cranial origin, which we have already considered. Each spinal nerve arises by two roots, which spring respectively from two of the fissures of the lateral halves of the cord, as has been men- tioned ; but these two roots soon join with each other to form the nerve, before it escapes from the spinal canal, to be dis- tributed to the regions which it is destined to supply. THE MEMBRAlfES OF THE SPINAL CORD. As was the case with the encephalon, the spinal cord is in- vested from within outward by a membrane of nutrition^ the pia mater ; a membrane of lubrication^ the arachnoid ; and, finally, a membrane of protection^ the dura mater. These three coverings differ in some respects from those covering the brain, but the differences have little if anything to do with the clinical aspects of the spinal cord, and they can be ascertained, if you desire to know them, by reference to any text-book on descriptive anatomy. THE CEREBRO-SPINAL FLUID. As mentioned in connection with the ventricular cavities of the brain, the spinal cord is immersed, as it were, in a fluid, the '' cerebrospinal Jluid,'^^ which has free entrance to and egress from the ventricles of the encephalon, since its function is to regulate and equalize the pressure ' upon the nerve centers, when the blood supply suffers variations, as it does during respiration, in sleep, and in certain diseased conditions. This accounts for the fact that pressure made upon a ''spina bifida" — a tumor containing this fluid pro- truding through an opening due to a congenital absence of the spinous processes of the vertebrse — often creates brain symptoms, if sufficient to create excessive intra-ventricular pressure. The greater part of this fluid is contained in what is known ' Hiltou considers this fluid as analogous, in respect to its function, to the elastic cap- sule of the various solid viscera. " Rest and Pain," London, 1876. THE CEREBROSPINAL FLUID. 293 as the sub-ai^acJinoidean space, which is situated outside of the cavity of the arachnoid, between its inner layer and the pia mater of the cord. Its quantity was estimated by Ma- gendie as about two fluidounces in the human subject ; but a somewhat larger amount can be obtained by making an opening in the lumbar region and a counter-opening in the region of the head, so as to allow of the influence of atmos- pheric pressure in forcing its escape outward/ This fluid may be drawn out of the spinal canal of a living animal, either by means of a simple trocar or a trocar at- tached to a suction tube. In the former method, no apparent influence of a detrimental character seems to follow a mod- erate escape ; but, when a suction force is used to still fur- ther draw olf the fluid, the animal becomes enfeebled and subsequently affected with symptoms of motor paralysis. The cerebro-spinal fluid is rapidly reproduced after its with- drawal, and is probably secreted by the pia mater. The fact that an increase of the intra-cerebral pressure will result in coma, if sufficiently intensified, is shown, in a clinical way, upon the human subject, by compression of a spina bifida ; and the same result was proved by Magendie, who injected water into the sub-arachnoidean space of animals, and thus artificially induced a state of profound coma. The point of communication between the sub-arachnoidean space of the spinal canal and the ventricular cavities of the brain is situ- ated in the fourth mntricle ; hence, the fluid has to pass up- ward, through the aqueduct of Sylvius, to reach the third ventricle, and through the foramina of Monro, to enter the two lateral ventricles of the cerebrum. Hilton "" claims that the basilar process of the occipital bone, which is the seat of some of the more important parts of the encephalon, is not in actual contact with the adjacent brain, but has a layer of the cerebro-spinal fluid interposed as a water-bed to protect the parts from injury from any form of concussion, and a similar condition probably exists in other parts. ^ A. Flint, Jr., op. cit. ^ Op. cii. 21 294 THE SPINAL COED. APPEARANCE OF A TRANSVERSE SECTION OF THE SPINAL CORD. The arrangement of the gray and white substance of the spinal cord is seen only on a transverse section. In order to properly appreciate the special points in the construction of these two portions, several transverse sections must be made at different heights in the cord, since the relative proportion of the gray and white substance differs in the cervical, dorsal, and lumbar regions. The regions usually selected for these transverse sections are the upper cervical portion, the center of the cervical enlargement, the center of the dorsal region, the lumbar enlargement, and the terminal portion of the cord. In the cervical region, the white substance is the most abundant ; in the dorsal region, the gray matter is relatively smaller than at any other point ; while, in the lumbar enlargement, the gray matter is the most extensively developed. When we view the appearance of any portion of the spinal cord on transverse section, we will perceive that the gray matter is arranged in the same general way in all of its differ- ent regions. This has been compared to the capital letter "H," since its two lateral halves are connected together by a transverse band, •' the transverse commissure of the gray substance." Each lateral half of the gray substance is crescentlc in form, thus presenting an anterior and a pos- terior projection, termed the anterior and posterior horns,' } The anterior horns, or cornua, arc studded with large characteristic cells, which are unipolar or multipolar. Certain of these cells are possessed of a peculiar process, which differs from its companions in not branching, and in increasing in size as it passes away from the body of the ceil. This is known as the " axis cylinder process," and it is claimed that it becomes clothed with myeline and is directly continuous with the axis cylinder of a motor nerve. We owe the discovery of this process in the human being to Deiters (" Un- tersuehungen Uber Gchirn u. Riickenmark," 1868), who asserted that it was also to be found appended to all central nerve cells; although, in 18Y4, R. Wagner ("Ilandworter- buch ") had observed a similar prolongation, sometimes two, in the central nervous organs of the torpedo, and Remak ("Deutsche Klinik," 1854, Nro. 27) had, in 1854, described the same peculiarity of structure in the anterior horn cells of the spinal cord in the ox. Deiters has been confirmed by a number of observers, among others by Max Schultze, Jolly, Gcrlach, Arnold, KoUiker, Arndt, Koschennikoff (see Ilenle, •' Norvcnlehre," 1879, ^ 20). These cells are distributed in groups, which arc differently situated in different regions. (L. C. Gray, "Annals of Anat, and Surg. Soc," Oct., 1880.) APPEARANCE OF A TRANSVERSE SECTION. 295 tlie former of whicli is broad and blunted, and does not reach the surface of the cord, while the latter is thinner and more pointed, and approaches the exterior surface near the point of attachment of the posterior roots of the spinal nerves. The white substance consists of the following component structures : 1, nerve fibers ; 2, blood-vessels ; and 3, connec- tive-tissue elements. The gray matter, called also the '' vesic- ular neurine," consists, 1, of nerve cells of variable shapes and sizes ; 2, nerve fibers ; 3, blood-vessels ; and 4, connective-tis- sue elements. In the w^hite substance, the nerve fibers are variable in point of size, and have a medullary sheath, but no investing membrane. In the gray matter the nerve fibers are small, and, in the posterior horns, form plexuses. The nerve cells are large and multipolar in the anterior horns, and smaller in the posterior horns. Fig. 111. — Section of the cord below the Fig. \\2.— Section of the cervical enlccrgc- medulla oblongata. (Sappey.) mcnt of the cord. (Sappey.) Fig. 111. — 1, anterior median fissure; 2, posterior median fissure; 3, gray commissure, much thicker here than lower down ; 4, white commissure formed by the decussa- tion of the anterior columns ; 5, anterior cornu ; 6, posterior cornu ; 7, lateral cornu. Fig. 112. — 1, anterior fissure ; 2, posterior fissure : 3, 3, anterior columns of most authors; 4, 4, lateral columns (these columns in reality pass beyond the anterior cornua, and the anterior columns occupy less space than is here allowed them) ; 5, posterior col- umns ; posterior commissure (here very narrow ) ; 7, reticulated arrangement of the gray and white matter at the junction of the two cornua ; 8, anterior cornu ; 8, ante- rior cornu, in which the multipolar cells are distributed into three principal groups; 9, posterior cornu ; 10, fifth pair of cervical nerves. Passing through the center of the gray commissure, and extending for the greater portion of the length of the cord, 296 THE SPINAL CORD. may be seen a small canal — tlie central canal of the spinal cord.^ That portion of the gray commissure which lies in front of this canal may be called the "anterior gray commis- sure," while the portion which lies behind it is called the 1^3 Fig. 113. — Section from the dorsal region Fig. 114. — Section of the lumbar enlarge- of the cord. (Sappey.) ment of the cord. (Sappey.) Fig. 113. — 1, anterior fissure; 2, posterior fissure ; 3, anterior column situated within the corresponding cornu, and decussating in the median line with the column of the op- posite side ; 4, 4, lateral column reaching to the anterior column, but separated from it by no distinct line of demarkation ; 5, posterior column ; 6, 7, section of the columns of Clarke, situated at the two extremities of the gray commissure, at the junction of the anterior and posterior cornua, and 9ontaining large multipolar cells ; 8, anterior cornu; 9, posterior cornu; 10, posterior root of dorsal nerves. Fig. 114. — 1, anterior fissure ; 2, posterior fissure ; 3, 3, anterior columns of most authors; 4, 4, lateral columns of most authors ; 5, posterior column ; 6, gray commissure and central canal, and, to the right and left of the latter, the orifices of two longitudinal veins ; 7, reticulated arrangement of white and gray matter ; 8, anterior cornu ; 9, posterior cornu ; 1 0, posterior root of the lumbar nerves. "posterior gray commissure." In front of the gray commis- sure a band of white nerve substance connects the two lat- | eral halves of the cord, to which the term "anterior white " commissure " is applied. We can see, by such a transverse section, that the poste- rior horns divide the lateral half of the cord into two great | subdivisions, the one lying anterior to it being called the antero-lateral column^ and that posterior to it being known as the posterior column. In the colored plate, which is taken from the admirable work of my friend and colleague Profes- ' This canal i8 continuous, above, with the /o?/r/A ventricle of the brain ; and the aque- duct of Sylvius is considered by some anatomists as a continuation of it above the fourth ventricle. Fig. 115. — Diagram illustrating the relations of the nerve-fiber tracts in the spinal cord. The section is supposed to be taken transversely through the lower part of the cervical enlargement (slightly modified from Flechsig by Hammond) : Anterior Median Fissure. Posterior Median Fissure. Intermediate Fissure. Anterior Gray Cornu. Posterior Gray Cornu. Gray Commissure, with Central Canal. Uncrossed Pyramidal Tract (Flechsig), or Column of Tiirck. Fundamental Part of the Anterior Column (Anterior Koot-Zones of Charcot and liis pupils). Anterior Part of Lateral Column. Crossed Pyramidal Tract of Lateral Column. Direct Tract from Lateral Column to Cerebellum. Column of Burdach, Posterior Root-Zones of Charcot and his pupils. Column of Goll. The posterior columns of descriptive anatomy include the fields M and N extending on the surface firom B to E. The antero-lateral columns extend on the surface from R to A. Their anterior division includes the fields G and II; their lateral division, the fields K, L, and I. CLINICAL SUBDIVISIONS OF THE COED. 297 sor Hammond, it will be, however, perceived that the simple anatomical divisions of the cord have been modified by patho- logical researches, so that certain special regions are now des- ignated, and some are named after the investigator who first discovered their function. Thus, to-day, we more commonly read of the columns of Goll, of Tiirck, of Burdach, and of the '^anterior root zone" and the ''posterior root zone," than of the anatomical terms with which you are doubtless more familiar. This is not without benefit to those who expect to master the mechanism of the symptomatology of the more important types of spinal diseases, although it may for a while tend to confuse you ; since the situation of lesions can be thus more simply expressed than in attempts to use terms which are inadequate to convey the idea. The anatomical subdivisions of the cord are fast becoming obsolete terms with the alienist, since they are based upon a purely structural foundation, irrespective of the physiological properties of the different parts. A few words of explanation of this selected plate ' will assist you, I trust, in mastering these new terms so readily that you will be able to follow my subsequent remarks with as much ease as if you had not been so long accustomed to the terms which will be, to a great extent, discarded. You will perceive that the gray matter is shown with its two ante- rior and two posterior horns (D and E) ; and also the antero- median and postero-median fissures, separating the cord into two lateral halves. In the anterior part, lying on each side of the antero-median fissure, are seen the "columns of Tiirck" (G), which are also called the "direct pyramidal columns," from the course of the nerve fibers which form them. On either side of these columns, extending backward toward the line of the transverse commissure of the cord, are the two re- gions (H) which, from their relation to the anterior roots, are called the "anterior root zones." ^ As we pass still farther backward, we next meet the two lateral columns (I), which, as you will see, are limited behind by the posterior horns of ' See Fig. 115. * Called also the ^'- anterior fundamental column.'''' 298 IHE SPINAL CORD. gray matter. Thus the antero-lateral column of the anato- mist has already been split up into three distinct i^ortions, each of which is specially named.' This lateral column is sometimes further subdivided into the "direct cerebellar column" and the ''crossed pyramidal column," as shown in the colored plate taken from Ham- mond, and also in an admirable schematic drawing which I have copied from Seguin.'* Behind, and adjoining the posterior horns of gray matter, you will see two greenish-colored portions (M), the posterior root zones, or the " columns of Burdach" ; while upon either side of the postero-median fissure lie the " columns of GoU " (N), which are colored pink. P Fig. 116. — Transverse section of the spinal cord and center. (Seguin.) A, anterioi' median fissure ; P, posterior median septum : 1, columns of Goll ; 2, columns of Burdach ; 3, direct cerebellar column ; 4, crossed pyramidal column ; 5, lateral column ; 6, anterior fundamental column ; 7, direct pyramidal column (column of Tiirck) ; 8, posterior gray horns ; 9, anterior gray horns. Stippled part — gray mat- ter. Shaded part — aesthesodic system. Unshaded part— kinesodic system. We can, again, thus perceive that the "posterior column " of the simpler classification, with which you are familiar, comprises the " columns of Goll and of Burdach." * See researches of Flcchsig, of Leipsic, regarding the course of fibers in the medulla oblongata and spinal cord. - "Medical Record," 1878. PATHS OF CONDUCTION IN THE SPINAL CORD. 299 FUXCTIOXS or THE SPII^AL CORD. Now, the questions may naturally arise to your minds : Why is such a digression from previously accepted terms so universally used, in preference to those more familiar and, possibly, simpler terms of nomenclature? Why should the columns of Tiirck, Goll, and Burdach be separated from each other when no anatomical line of division seems to have been created ? Is the arrangement not a strained attempt to mys- tify and confuse the medical student, and does a sufficient ground exist for so great a departure from previous methods of description ? In reply to such anticipated questions — and they have been asked of me many times — I would respectfully draw your attention to such points in the physiology and pathology of the spinal cord as will help to show you the necessity which existed for such modifications of previously familiar terms, as well as the advantages which are gained by those subdivisions of the cord which are now household words to the specialist on nervous diseases. I would first call your attention to the fact that the spinal cord is an organ of conduction. The motor impulses, which affect the muscles of the different parts of the body, are un- questionably transmitted through it from the brain to the part destined to be acted upon ; hence we know that centrifu- gal impulses need not be created in the cord itself, but may be transmitted from the brain. We see this illustrated in the hemiplegias of cerebral origin. We also have equally positive proof that certain sensory impressions are conducted by means of the spinal cord to the brain ; hence, centripetal im- pulses or impressions must pass upward in some instances. We see this fact verified in the hemi-ansesthesia which often accompanies motor paralysis of cerebral origin. Now, it can be stated, with an approach to accuracy, that it is as certainly proved that the motor impulses travel along the anterior half of the spinal cord, while the path of sensory impressions!^ in- timately associated with the posterior half of the spinal cord.' ^ This statement is only approximately correct, as will be shown in the text of subse- quent pages. 300 THE SPIRAL CORD. If you will direct your attention, in tlie second place, to the fact that the motor fibers found in the anterior roots do not decussate ^ until they reach the medulla oblongata, while the sensory fibers found in the posterior roots ascend in the columns of Burdach for a short distance only, when they pass into the gray matter of the opj^osite half of the cord, we can understand why any interference with the motor fibers (if below the medulla) produces paralysis on the corresponding slde^ while any interference with the sensory roots produces ancBsthesia on the opposite side of the body. Again, the antero-lateral columns of the cord, which com- prise the portion situated between the antero-median fissure and the point of attachment of the posterior roots of the spinal nerves, are not sensible to any form of direct irritation." This is a point of some clinical interest, since, in certain mor- bid conditions, a marked change in this respect occurs, and the inexcitable portions may then give rise to abnormal sensa- tions and to spasm of the muscles. If these columns be divided, voluntary motion is lost in all the parts below the point of section ; while, if aU the other portions of the cord be divided, leaving the antero-lateral columns intact, the power of voluntary motion remains. The columns of Tiirck and the crossed pyramidal columns are colored alike in the plate. This indicates a probable similarity of function be- tween these two subdivisions of the cord. The gray matter of the cord seems to be most intimately associated with the transmission of sensory impressions to the brain, and that portion which lies in close relation to the central canal of the cord is apparently the most important of the transmittory apparatus.' If the entire gray substance of the cord be divided, little or no injury being done to the ^ As regards this point, Brown-S6quai'd says : " In animals, there seems to be in the spinal cord itself a decussation of a few of the motor conductors." I do not think, how- ever, that such a decussation can, as yet, be verified in man. If such decussation docs exist, it is present only in the cervical region, and not in the dorsal and lumbar regions. ^ The experiments of Vulpian seem to prove that the internal portion of the anterior column docs exhibit a trace of excitability in the normal state. * The experiments of Brown-Sequard seem to warrant this conclusion. Very little gray matter may, therefore, suffice to convey all sensory impressions. I FUNCTIONS OF THE SPINAL CORD, 30I white substance, all power of perceiving sensations seems to be destroyed below the point of section. In addition to this function, the gray matter of the cord seems to exert a con- trolling influence upon the nutrition of muscles and other tissues, since, w^hen the anterior portion becomes the seat of disease, the muscles often undergo atrophy, and occasionally joint diseases develop. This so-called "trophic function^^ \^ not yet thoroughly understood. Finally, the gray matter of the cord is known to embrace several centers, the two most important of which are the cilio-spinal center and the genito- urinary center. The former of these is situated in the cervi- cal region, at its lowest part,' and exerts an influence upon the pupil of the eye and the skin of the face and neck ; hence it is often a valuable guide to determine the height of a lesion in the spinal cord, since the pupils show changes when it is involved that are of value to the diagnostician. The latter center (genito-urinary) is situated in the dorso- lumbar portion of the cord, and often creates symptoms, when disease of the cord exists, referable to the bladder and genital organs. Certain smaller centers, having a vaso-motor function, are described by some authors ; but their situation and special functions are either unknown or of little practical utility in diagnosis, while the physiological centers of the cord are, as yet, a matter deserving further investigation be- fore any positive statements can be made concerning them. In the posterior column of the cord, comprising the col- umns of Goll and of Burdach, there exists a certain amount of white substance, whose function seems to be chiefly to act as commissural fibers between certain portions of the spinal ^ The researches of Waller, Budge, and Brown .Sequard would indicate the limits of this center between the fifth cervical and second dorsal vertebrae. It exists in each lat- eral half of the cord. It presides over the vaso-motor nerves for the vessels of the cor- responding eye and side of the face and neck. Vulpian places its limits as low as the fourth dorsal, and Claude Bernard as low as the seventh dorsal, while Schiff carries its limits as high as the medulla itself. Vulpian's conclusions indicate the gray matter of the cord as positivcl;/ incapable of cxcitabilitii ; but he attributes slight excitability to the anterior fasciculi of the cord and great excitability to the posterior columns. In these deductions, he differs somewhat from the results of Chauveau, made, in 1861, upon the domestic animals. 302 THE SPINAL CORD. cord. This portion has also some important relation to the power of coordination ' of muscular movement, since disease of this region of the cord is followed or accompanied by dis- orders of motion, called ataxic symptoms, which are not due to paralysis. Like the cerebrum, the spinal cord has the inherent power of presiding over certain muscular acts. It is now quite con- clusively proven that the automatic acts of walking, standing, swimming, and, to some extent, playing upon musical instru- ments, dressing, etc., are largely controlled by the spinal cord alone. It is unquestioned that certain of these acts can be made so mechanical that the spinal cord is slowly and pain- fully educated to perform them without any aid from the cerebrum. It is not generally accepted, however, that the gray matter of the cord has anything to do with the attribute of consciousness. FIBERS OF THE SPII^AL CORD. There are probably three varieties of fibers within the sub- stance of the spinal cord, viz., motor fibers, sensory fibers, and commissural fibers. Each of these has been already men- tioned, and some points of general interest pertaining to their situation and function have been given ; but there are still some points which must be understood before we are able to intelligently discuss the symptoms of spinal affections. The motor fibers are contained in the anterior roots of the spinal nerves and escape from the substance of the cord in the region of the anterior horns of gray matter. If we trace them from the nerve trunk toward the center of the cord, we shall find that they penetrate the anterior horns, and are in immediate connection with the prolongations of the motor cells of that portion of the gi'ay matter. Certain motor fibers can be also traced toward the brain, passing upward in the an- terior portion of the white substance of the cord, while pro- longations of the motor cells of the gray matter are also found ' The cerebellum has also much to do with the coordination of muscular movements. The reader is, therefore, referred to page 64 of this volume. VARIETIES OF FIBERS IK THE CORD. 303 'iG. 117. — Nerve cell from the anterior cornua of the sphial cord of the calf macerated for a short time in iodized serum ; magnified 600 diameters. (Schultzc.) a, a, axis-cylinder prolongation ; h, b, 6, 6, branching prolongations. 304 THE SPINAL CORD. to be associated with these fibers, which ascend to the brain in the white substance. K'ow, this connection between the motor fibers and the nerve cells, and the second connection of the cells with fibers going to the brain, would seem to suggest the pleasing hypothesis that the motor impulses are sent first from the brain to the cells of the cord, and from them, through the motor nerves, to the muscles ; and that, when the cord is taught to perform certain automatic acts without the interven- tion of cerebral action, these cells themselves are the exciting organs of the motor impulses (since they are the elements which are most probably concerned in the reflex movements of the spinal cord). We know that the legs of a frog can be made to perform muscular movements after the head has been taken off, by simply stimulating the sensory nerves ; and we see the same reflex movements occurring in paralyzed limbs, which are out of the voluntary control of the brain. To ex- plain these phenomena, we must believe that the motor cells of the cord are capable, when called upon, of performing many muscular acts, some of which would seem too complex for spi- nal control without cerebral assistance, as walking, swimming, playing upon musical instruments, etc. By referring to the diagram, ' which is shown you upon the blackboard, where a multipolar spinal cell is magnified, you will easily understand how these various poles can be connected with certain motor, and probably, also, with sensory fibers ; hence, it can be seen that the cell may receive certain sensory impressions from some poles and send out certain motor impulses to the mus- cles by means of others, thus accounting for the muscular movements which follow the irritation of sensory nerves. | The sensory fibers enter the cord at the posterior roots of the spinal nerves. They are intimately connected with the posterior horns of the gray matter. They probably ascend and descend in the columns of Burdach for a certain distance, and then decussate. The decussation of the sensory fibers is accomplished either by the passing of the fibers themselves to the opposite side of the cord, or by the prolongation of some ' See Figs. 117 and 118 of this volume. PATH OF SENSORY IMPULSES IN THE COED. 305 Fig. 118. — MuUipolar nerve cell from the anterior cornu of the spinal cord of the ox ; magnified 200 diameters. (Deiters.) 306 TEE SPINAL CORD. of the poles of the spinal cells into the gray matter of the opposite side. The decussation probably takes place exclu- sively in the gray matter. While this decussation seems positively proven by all physiological experiment, little of a positive character has, as yet, been shown by actual anatomi- cal demonstration. The sensory nerves are in communication with the cortex of the encephalon, probably, by means of the gray matter of the spinal cord, which acts as a conducting medium for the centripetal impulses. As before mentioned, the gray matter which surrounds the central canal of the spinal cord seems to be the chief channel for the transmission of sensory impressions from the trunk and the extremities to the brain. Thus we apparently have in the spinal cord a Fig. 110. ■TranavLi'sc section of tltc (J ra}i substance of the anterior cjrnua of (he spina' cord of the ox, treated loith nitrate of silver. (Grandry.) conducting shaft, to which the sensory nerves become joined, and which conducts the impressions received through them || to the ganglia or the cortex of the encephalon. It is evi- dent, therefore, that the sensory nerves are not continuous COMMISSURAL FIBERS OF THE CORD. 307 MS S M fibers between the brain and the parts to which they are dis- tributed, in which respect they differ somewhat from the motor nerves, whose fibers are indirectly carried to the brain, although the motor cells of the cord are probably interposed. The commissural fibers of the cord probably exist in the white substance of the posterior columns.' The spinal cord may properly be considered as a mass of superimposed ganglia ; hence, a great ne- cessity exists for certain fibers which shall tend to unite the different parts, and thus conduce to the perfect harmony of action of the whole. It is not possible to de- monstrate the existence and exact situa- tion of such fibers, but all i)hysiological and pathological deductions seem to sus- tain this hypothesis. These fibers have, probably, a most important influence in the proper coordination of muscular movement. The above diagram illustrates, in a very simi)le way, the general course of the motor and sensory paths of the spinal cord. The outer lines of the diagram show the general out- line of the spinal cord, which merges into the medulla oblon- gata, above ; while the motor fibers are designated by the let- ter M, and the sensory fibers by the letter S, both where they enter the spinal cord and where they escape from it. This diagram shows that hotJi the sensory and motor fibers decus- sate ; but that the motor fibers cross in the medulla oblongata only, while the sensory fibers cross soon after they enter the spinal cord, when they join with the gray matter, and use that as a means of transmitting their sensory impressions to the brain. The diagram also shows that the sensory fibers spring from the posterior roots of the spinal nerves, since the ' A. Flint, Jr., op. cif. The experiments made to prove this point may be found in ahnost any of the later treatises on physiology. S' Fig. 120. — Course of motor and sensory paths in the spinal cord. (Brown- Sequard.) D, decussation of pyramids ; M, motor paths ; S, sen- sory paths. 308 THE SPINAL CORD. ganglionic enlargement is depicted uj^on the sensory fibers as two small black dots. Now, it is easy to understand, by means of this diagram, why any lesion above the medulla ob- longata must produce all of its symptoms on the side of the body opposite to that of the exciting cause, since the motor and sensory fibers both decussate below that point ; ' w^hile it also shows that any lesion below the medulla oblongata must produce motor symptoms upon the same side as the lesion, and, probably, sensory manifestations upon the side opposite to it, since these latter fibers decussate for the entire length Fio. 121. — Nerve cell from the ferruginous substance which forms the floor of the rhom- boidal siuus^ in man ; magnified 350 diameters. (Kolliker.) of the spinal cord. In all spinal lesions, causing motor paral ysis, the body is affected below the point of disease, since the conducting fibers to the brain are cut off ; while, in lesions of the posterior portion of the spinal cord, the nerves of that ^ This is not absolutely true, as all of the motor fibers do not decussate in the medulla. The reader is referred to page 327 of this volume for the results of the investi- gations of Flechsig. THE SPIRAL CORD AS A NERVE CENTER. 309 region may be rendered incapable of action, but the parts below may be still capable of perceiving sensory impressions, provided that the gray matter is left intact, or sufficient of it remains to act as a conducting medium to the brain. The commissural fibers of the spinal cord are not depicted in this diagram of Brown- Sequard, since little is positively known as to their exact situation or function. As they are probably confined largely to the posterior half of the spinal cord, and as they are also probably intimately associated with the coordination of movement, it is not difficult to see why the symptoms of ancestJiesia and ataxia should march hand in hand, when the spinal cord is diseased in this region ; and why neuralgic pains should be created by the irritation to the sensory nerves, rather than muscular spasm, which would only exist if the motor nerves were irritated. This general subject will, however, be more fully discussed in connection with the clinical aspects of locomotor ataxia and degenera- tion of the posterior portion of the cord (the columns of GoU and Burdach). Finally, two points are especially evident in respect to the nerve fibers of the spinal cord. These may be stated as dis- tinct propositions : 1. The nerve fibers of the anterior roots have less numer- ous connections with the cells of the gray substance of the cord than are possessed by those of the posterior roots. 2. The morphological distinction between the fibers of the anterior and posterior roots is, that the former are directly attached to the nerve cells by means of their nerve prolonga- tions, while the latter are only indirectly attached to the nerve cells, since they form nerve plexuses before becoming united with the prolongations of the nerve cells.' THE SPINAL CORD AS A NERVE CENTER. If the cord be separated from the brain in a living animal, it may still act as a nerve center, independently of the brain ; but, since the spinal cord is then in communication only with ^ A. Flint, Jr., op. cit. 22 310 THE SPINAL CORD. the nerves which arise from it, it can only affect the spinal nerves, and not those of cranial origin. This automatic ac- tion of the spinal cord is of a purely reflex type under such conditions. It can be demonstrated by exciting some one of the sensory nerves, when a muscular response will be created ; hence the term ''excito-motor" is of ten applied to this type of manifestation, whether occurring during life, as the result of disease or peripheral irritation, or after death, as in the physiological experiment alluded to. There are certain acts which are constantly occurring in the body, such as the move- ments of the pupils, of the intestinal canal, of respiration, etc., which are properly classed as reflex in type, but which are not dependent upon the spinal cord alone. In fact, all acts are classed as belonging to the reflex type, which are the direct result of some form of sensory irritation; but the term is generally used, in discussing the spinal cord, in its most restricted sense, where the muscular act is purely in- voluntary, the result of some direct irritation of a sensory spinal nerve, and confined to regions of the body over which the spinal cord exerts a direct influence. Thus, we often see the muscles of a paralyzed limb suddenly thrown into in- voluntary and unexpected contraction, when a draught of cold air strikes the skin, or when any form of irritation is di- rectly applied to it ; while such spasms are common in certain forms of spinal disease which tend to create irritation of the spinal structures, irrespective of any apparent exciting cause. We have already referred to certain vaso-motor centers ' ' The vaso-motor nerves for the trunk, extremities, and abdominal viscera probably originate in the following manner (see researches of Vulpian, Schiff, Cyon, Claude Ber- nard, and the later researches of Dastrc, Tiaffont, and Morat) : Those for the upper extremities are derived — 1. From the inferior cervical and superior thoracic ganglion, uniting at the brachial plexus, close to the first .rib ; 2. From the nerve roots of the brachial plexus ; 3. From the thoracic cord of the sympathetic, and from the nerve roots of the third, fourth, fifth, sixth, and seventh dorsal nerves, principally from the third and seventh. Those for the lower extremities proceed — 1. From the spinal cord with the sciatic and crural nerves : 2. From the abdominal cord of the sympathetic. The abdominal viscera are supplied with fibers arising from a considerable length of CELIO-SPINAL AND GENITO-URINARY CENTERS. 311 which exist in the substance of the spinal cord, the two most important of w^hich are the cilio- spinal center and the center for the genito-urinary apparatus. The former of these is situated in the cervical region, and exerts some marked eifects upon the eye, face, and neck ; while the latter is situated in the dorso-lumbar region of the cord. If the medulla oblon- gata be considered as the upper expansion of the spinal cord (and there are many anatomical reasons for thus considering it), all the centers mentioned as situated in that ganglion may be included among the spinal centers of automatic action. Some authors have gone so far as to locate in the spinal cord certain centers which preside over the acts of micturition, de- fecation, parturition, erection, etc., and experiment seems to give reason to hope that a more definite ground will be af- forded for such belief, although little of a positive character can as yet be given in regard to their situation. It has also been claimed that the spinal nerves exercise a tonic action over the muscles which move the different por- tions of the skeleton, in the same way as the vaso-motor nerves exercise such a power over the muscular libers in the coats of the blood-vessels ; and certain experimental pheno- mena, chiefly the gaping of a wound in muscular tissue, have been advanced to sustain this theory. It is not, however, fully sustained by all the facts, ' and is not generally ac- cepted by the leading physiologists. We have come to learn that each group of cells — perhaps each cell — in this gray matter represents a certain kind of intelligence ; ' and that these cells are probably in communi- cation with one another by means of white fibers. It is the sum total of these intelligences that imparts to the cord its characteristics as an organ. As each one of these cellular the dorsal and lumbar cord, and running within the sheath of the splanchnic nerve, as well as by fibers from the abdominal cord of the sympathetic. The vaso-motor nerves of the head and face talcs their origin from what is known as the " cilio-spinal center," and when this center is destroyed there ensues a marked dilatation of the capillaries of the head and face. ^ For the discussion as to the merits and demerits of this theory, the reader is re ferred to the late text-book of Michael Foster on physiology. 2 L. C. Gray, "Annals of Anatomical and Surgical Society," October, 1880. 312 THE SPINAL CORD. groups and its inherent intelligence is more or less independ- ent of all others, so the combined intelligence of the cord's gray matter is independent of the combined intelligence of other collections of gray matter ; and it is a recognized fact that the spinal cord has a "function" of its own. This has been exemplified by experiments upon headless frogs and de- capitated human beings. Cut off the head of a frog, peimit it to recover from the shock of the operation, then pinch its skin, and it will hop away ; or, throw it into water, and it will swim. Place a drop of acetic acid upon the belly of such a frog, and it will endeavor to brush away the irritation with one foot. Now amputate the leg of this foot at the knee. The animal will make several futile attempts to reach the irritated spot with the stump, and, failing, will, after some hesitation, make use of the uninjured limb for this purpose. It is easy to repeat this well-known experiment of Pfliiger's.' Robin * witnessed some most instructive phenomena in a crimi- nal whose head had been removed an hour previous at the level of the fourth cervical vertebrae. The skin around the nipple was scratched with the point of a scalpel. Immedi- ately there ensued a series of rapid movements in the upper extremity, which had been extended upon the table. The hand was brought across the chest to the pit of the stomach, simultaneously with a semi-flexion of the forearm and inward rotation of the arm — a movement of defense, as it were. All this teaches us the more clearly to understand that it is the intelligence of the cord's gray matter that is called into play in a thousand actions that must take place without the aid of that conscious intelligence which we call "mind." The intel- ligence of the spinal cells is quite sufficient to enable men to walk, to play on musical instruments, to become experts in handiwork, to ride on horseback, whether awake or asleep, to become acrobats, and to unconsciously acquire such a hand- writing that its minute peculiarities shall be unerringly recog- nized by the trained eye. * Pfliiger, "Die sensorische Function des Riickenmaiks," 1853. « "Jour, de TAnat. et de la Physiol.," Paris, 1860. KINESOniC AND JESTHESODIG SYSTEMS. * 313 CLIKICAL POINTS PERTAININ^G TO THE SPINAL CORD. From the physiological experiments as to the functions of the different columns of the cord, it now seems possible to divide the spinal cord into two great subdivisions, which will be of interest from a purely clinical standpoint, as well as from a physiological aspect. The first of these includes the entire antero-lateral columns, and the anterior horns of the gray matter, and is the probable path of all motor impulses which traverse the cord, as well as the seat of "trophic influences " upon tissues. The latter includes the posterior columns and the posterior horns of the gray matter, and is the probable path of all the sensory impulses, while it also is associated with the function of coordination of movement. Now, both of these subdivisions include several parts of the spinal cord, which have been separately named in previous pages; hence, the term '^ system" is applied to both, the former being named the '' Mnesodic system,'^'' and the latter the '' cBstliesodic system^ These names will be constantly used, therefore, when the portions of the cord which con- vey either motor or sensory impulses are spoken of as a whole ; while the other names applied to special portions of the cord will chiefly be used in defining the situations of special lesions whose symptomatology may be under dis- cussion. If we are to attempt to grasp the symptoms by which the various lesions of the spinal cord may be recognized during life, and to understand why certain effects must be produced (when the situation of the lesion is known to us), we must make some classification of the diseases which affect the spinal cord on such an anatomical and physiological basis as shall naturally tend toward the constant application of these branches of medical science to the symptoms presented by the patient. It has been customary with most of the late authors upon the special subject of nervous affections to con- sider the diseases of the motor regions and of the sensory regions of the cord separately; using the term ''systematic 314 THE SPINAL CORD. lesions''^ to express the fact that all of those diseases, which are not purely local, affect either the kinesodic or sesthesodic systems. When we speak of systematic lesions, therefore, we mean those types of disease which tend to diffuse them- selves, for a greater or less extent, upward and downward, without extension to the adjacent columns ; thus the columns of GoU and of Burdach may be involved in the sesthesodic system, the lateral columns and the columns of Tiirck may be involved in the kinesodic system, while the anterior or posterior horns or central part of the gray matter may be the seat of disease, irrespective of the other parts of the cord. In contradistinction to the systematic lesions, certain types of disease tend to spread laterally, and thus to involve different columns of the cord in succession. These are grouped under the general head of "focal lesions " or '' non- systematic lesions,^'' In this form of degeneration, or of new tissue development, the extension is usually limited in a vertical direction, but *it may extend, laterally, not only to diverse columns, but may even involve both the kinesodic and sesthesodic systems in its progress. It will exceed the proper scope of the course of lectures which I have prepared for this winter, to enter into a full de- scription of the symptoms of all of the diseases of the spinal cord ; but it is important that you start with a genei^al classi- fication of the diseases which may affect this region, in order that you may properly understand the meaning of terms which you will find growing into use with astonishing rapid- ity. It is also to be remembered that the classification which I have given you is based on anatomy and pathology, and may differ markedly from those of some authors with which you may be familiar ; a little study will, however, remove all confusion, and perhaps add to your more perfect comprehen- sion of the subject. SYSTEMATIC LESIONS OF JESTHESODIG SYSTEM. 315 A CLASSIFICATION OF THE DISEASES OF THE SUBSTANCE OF THE SPINAL CORD. (after SEGUIN.) r Sclerosis of the columns of GoU, Lesions of the ^s- J Sclerosis of the columns of Burdaoh (locomo- thesodic System, j tor ataxia), (^ Ascending degeneration, f Sclerosis of the anterior columns, SYSTEMATIC " | Sclerosis of the lateral columns (tetanoid para- LESIONS. ^ plegia), Degeneration of the postero-lateral columns, ■< Myelitis of the anterior horns (atrophic spinal paralysis). Degeneration of the ganglion cells of the ante- rior horns (progressive muscular atrophy), Central myelitis. Traumatism of the cord, Lesions of the Ki- nesodic System. " NON-SYSTEM- ATIC" OR "FO- CAL" LESIONS. Compression of the cord, by \ Bone or I Tumors, -{ Transverse sclerosis of the cord. Transverse softening of the cord, I Haemorrhage into the cord, (^ Tumors of the cord. "SYSTEMATIC LESIONS'^ OF THE " ^STHESODIC SYSTEM." In the table ' which I have written out for your inspection, you will perceive that the systematic lesions may affect either the sesthesodic or kinesodic systems of the spinal cord, while the focal lesions are not thus separated, since they tend to extend in a transverse direction, and thus may be found in both. As the sesthesodic system presents only two well-recog- nized and understood conditions, we will first study the gen- eral effects of extending disease which is confined either to the columns of Goll or of Burdach. We might begin, possibly with advantage, by stating that the general results of any lesion situated back of the posterior gray horn of the cord must manifest itself, if our previous de- ductions are correct, by symptoms referable only to sensation and coordination. This we find to be approximately correct. We have in this type of cases ancesthesia^ Jiypercesthesia^ or numbness., and also pain (usually possessing some special characteristics which are of clinical value) ; while coordi- nation is unquestionably affected as well, since a peculiar See page 315 of this volume. 316 THE SPINAL CORD. disorder of voluntary movements, which constitutes true "ataxia," is usually developed. Our previous statements as to the path of the motor impulses of the cord seem to be con- firmed by the absence of either spasm or true paralysis of the muscles below the lesion. The question now arises, " Can we tell whether the disease is confined to the columns of Goll or of Burdach ? " We can undoubtedly locate the lesion in the opposite side of the cord from that of the body upon which certain symptoms are well marked ; but can we tell positively whether the lesion is pro- gressing in the inner or outer column of the posterior half of either side of the cord which shows the evidence of disease I SCLEROSIS OF THE COLUMJ^S OF GOLL. As regards the columns of Goll, I feel myself forced to say that I do not believe that localized disease can be positively diagnosed when confined to these columns; although, from certain pathological deductions, we can often infer that it exists^ since it has been found to occur as a secondary result of those other lesions which are capable of producing an as- cending or descending degenerative process in the spinal cord. As the columns of Goll are large and distinct in the cervical region of the cord, but become narrower and narrower as the lower portion of the cord is reached, the lesion of this column becomes more evident to ocular demonstration, when present, as you ascend the cord. The entire length of either column may be affected, or only portions of it. In the ascending form of secondary degeneration of these columns, the lesion is always observed above the seat of the exciting cause. This lesion has never been traced, so far as my researches go, above the ''calamus scriptorius." SCLEROSIS OP THE COLUMNS OF BURDACH (LOCOMOTOR ATAXIA). The columns of Burdach are the seat of sclerosis more commonly than those of Goll, since this type of change pro- gresses, as a rule, from the posterior root zones inward, and thus only affects the columns of Goll after those of Burdach PROGEESSIVE LOCOMOTOR ATAXIA, 3I7 have become seriously impaired. In all those cases where the symptoms of pain and alteration in the sensibility of parts precede those of ataxia, we find the columns of Burdach first affected with a systematic lesion, and, afterward, those of GqII. The investigations of Pierret and Charcot seem to de- monstrate that the condition of sclerosis of the columns of Bur- dach usually begins in the lumbar enlargement, and tends to creep gradually upward toward the medulla oblongata, so that the entire length of the cord may become hardened and atro- phied ; while the same condition of the columns of Goll is usually found to coexist, but may be looked upon as a sec- ondary result of the former. Now, we have mentioned certain peculiar symptoms which point, when present, to some disease of the posterior columns of the spinal cord, among which come pain, liyjpercBstliesia^ numbness^ ancEsfhesia^ and symptoms of incoordination (ataxia) when the disease is far advanced. We discover no motor symptoms, as the muscular power appears to be normal in all respects, except in coordinate movement ; and no ''tro- phic changes " in tissues are produced, as would ensue if the anterior portion of the cord were involved. It will help us to recognize this disease, if we will study a little more in detail each of these various manifestations of posterior spinal lesions. In the first place, the pains of this type of sclerosis are peculiar. They do not follow the course of special nerve trunks, as do neuralgic pains, but are more localized. They are vagrant in character, since they affect innumerable spots in the region which is presided over by the nerves connected with the diseased portion of the cord ; and so marked is this peculiarity that a patient who has long suffered with these pains can not well select any spot which has entirely escaped them. Again, the pains vary in their intensity, since they are more or less paroxysmal, and often show exacerbations due to atmospheric changes.' These exacerbations may occur every few minutes for some hours, and may then disappear for ' Dampness seems to increase the severity of these pains, thus oftqn tending to mis- lead the practitioner as to their rheumatic origin. 318 THE SPINAL CORD. days or weeks ; the area covered by them may vary from that of a small point to that of your hand ; and they may be re- ferred to the skin alone, the muscles, the joints, the bones, or, in rare cases, to the viscera. These pains are usually of a sudden character, and extremely severe. They assume the character of stabbing, tearing, or shooting sensations, which often cause the patient to shriek in agony ; while the skin over the circumscribed spot is rendered hypersesthesic to slight pressure, although firm pressure often affords relief. The terms '^fulgurating" and " terebrating " are of ten applied to these pains, from their sudden onset and their similarity to the effects of a passage of a strong electric current. In fact, the distinctive characteristics of the pain of sclerosis of the posterior columns of the spinal cord are so well defined that I seldom hesitate to predict the development of later ataxic symptoms from this guide alone. It is usually confined to the lower extremities (toes, foot, shin, calf, and thigh), but it sometimes affects the trunk and the upper extremity, and, in very rare cases, the head. It is to be differentiated from the pain of rheumatism or of a simple neuralgia, and, as it is the initial symptom of a serious and incurable disease, it should be recognized early. Touching upon this point. Professor E. C. Seguin, in a late lecture, puts the diagnosis of this affection, with his accus- tomed clearness, as follows : " The only two conditions in which pains somewhat resem- bling fulgurating pains occur, in my experience, are paralytic dementia and gout. In the former disease, slight fulgurating pains — 'smaller' pains, if I may be allowed the expression — ^ are described by the patients ; but, in many of these cases autopsy shows that, besides the cerebral lesions proper to the^ disease, the posterior columns of the cord exhibit pathological alterations ; so that these cases are, after all, quasi-tdiheiiG. The sharp pains of gout are short, stabbing pains in the skii of various parts of the body, compared by the patients t( the prick of a needle, cold or hot. There is no tendency t( repetition of the pain in one spot for hours or days ; the sen- TEE PAINS OF LOCOMOTOR ATAXIA. 319 sations appear in various parts of the body, and are bear- able. '* The differential diagnosis of fulgurating pains from the pains of neuralgia, strictly speaking, is very easy. In neural- gia the pain is in the course and distribution of one or two (single) nerve trunks and their branches ; it may be parox- }'smal, but does not assume the excessive irregularity of ta- ])etic pains, viz., agony for a few hours, and freedom from pains for hours, days, or weeks. The hypersesthesia, in ful- gurating pains, is at the seat of pain. In neuralgia, we find regular ' tender points ' along the nerve trunk, or where its l)ranches become superficial. The lightest touch causes pain in the painful districts in tabes, while the tenderness of nerves in neuralgia is usually demonstrable only by firm, localized pressure. Further, true neuralgia is' seldom bilat- eral, while it is the rule for fulgurating pains to appear on both sides of the median line — in both lower extremities, for example. A last important distinction is that neuralgia is relievable or curable, whereas fulgurating pains are practi- cally incurable, and fully relieved only by morphia injections. ''The confusion so often made between 'rheumatism' and the first stage of sclerosis is even less pardonable. Of course, no practitioner would mistake fulgurating pains for articular iheumatism ; the error is with respect to 'rheumatism,' so called, affecting muscular masses and aponeuroses. In these affections the pains are usually dull, nearly constant, and dis- tinctly aggravated by movements. Pressure must be firmly made upon the parts to produce pain, whereas in fulgurating pains the condition is one of cutaneous hyperalgesia under a slight touch. Again, this ' rheumatic ' condition is distinctly amenable to treatment (counter-irritants, etc.), whereas the pains of posterior spinal sclerosis are, in one sense, incurable." Now, this symptom may exist for years without the de- velopment of marked anaesthesia or of ataxia, and often both the patient and the physician are inclined to speak of these pains as dependent upon some rheumatic diathesis, rather than as a precursor of an incurable affection. The peculiar 320 THE SPINAL CORD. hypersesthesia which exists in the patches of skin affected with the pain, both during the paroxysm and sometimes for hours afterward, affords a point of great diagnostic value. As regards the second diagnostic symptom — ancBsthesia — it is claimed that an alteration in the sensibility of the af- fected parts can be detected in the earliest stages of the dis- ease, as well as later on ; but, in the former case, the loss of sensation is localized in distinct spots or patches of integu- ment (usually upon the lower extremities, but, possibly, upon the trunk and arms, if the disease be extensive), while, in the later stages, the soles of the feet become deprived of sensi- bility, and the 'ansesthetic condition tends to extend upward along the legs and thighs until the whole of the affected re- gions may be dead to all sensations. Now, it is this very con- dition of the integument that probably causes the symptom which is regarded by many physicians as pathognomonic of locomotor ataxia — staggering or falling, when the eyes are closed and the patient attempts to stand erect — and no test is more worthless of this special affection. I have seen a patient made to fall, when his eyes were closed, by simply freezing the soles of the feet so as to render them incapable of sensa- tion, while it is well recognized that the same symptom is met with in the anaesthesia which follows or accompanies hysteria, myelitis of the posterior horns, etc. That patients afflicted with locomotor ataxia do stagger and often fall, when obliged to stand erect with closed eyes, no one can deny, but that it has no special diagnostic value can now be as positively stated. In the final stages of sclerosis of the posterior columns, symptoms of ataxia develop. The walk of the patient now becomes of a peculiar character. The legs are jerked about in an aimless manner, and the feet are brought down in a stamping way which is totally different from the gait of pa- i-alysis.* The separate muscles, when tested, show an unim- ' This symptom may develop at a variable period from the commencement of the neuralgic pains (the duration of the pains varying from three months to ten or more years). The heel strikes the ground forcibly in walking. If the upper extremities are involved, the fingers and arms perform unnecessary movements to reach a given point, and oscillate when a given action is attempted. VARIETIES OF ATAXIC MANIFESTATIONS. 321 paired power, but the large groups of muscles can not be employed in rhythmical succession. The patient begins to notice, in the early symptoms of this condition, a sense of distrust in himself in crossing a street or in performing any act which calls for sudden and positive muscular coordina- tion. Later on, walking becomes almost impossible if the ataxic symptoms develop rapidly, and the patient is liable to fall, in his efforts to avoid any special danger, as in traveling the streets. One of the earliest evidences of incoordination of movement usually perceived by tabetic patients is a difficulty in direct- ing their feet toward any object of small size, such as a car- riage-step, stirrup, etc. A difficulty is also experienced by many in ascending long flights of stairs, as the equilibrium is preserved with some difficulty, on account of an uncertainty in placing the feet upon the stairs. Later on in the disease, the feet are swung in a circle, in contrast to the straight pro- gression of the normal step, since the equilibrium is thus more easily preserved. This has been compared to the swing- ing motion of the tight-rope performer. The sole of the foot is generally brought down after the heel strikes the ground, thus often giving a flapping sound to the step. The jerking gait of well-marked ataxia could never be mistaken for that of paralysis. When the upper extremities are affected, the motions of the hand show even more decided evidences of incoordination. Such patients, when asked to place the tip of their finger upon any designated spot on the face (provided the eyes are first closed, in order to prevent the use of vision as an aid to movement), utterly fail to perform the act, often touching a spot one or two inches from that upon which they intended to place their finger. With the eyes open, a glass of water is carried to the mouth with a trembling of the hand and partial spilling of its contents ; and the finger is placed upon any point designated upon the face by being suddenly darted forward, rather than by a deliberate movement. The hand- viTiting is markedly altered, especially in respect to the 322 THE SPINAL CORD. rounded letters, such as d^ ft, o, Ka c c; and all con- tractions are slow and wave-like." (E. C. Scguin, "Med. Uecord," 187S.) MYELITIS OF THE A^^TERIOR HORNS. 333 easily found in any of the special treatises on the treatment and diagnosis of nervous affections. JN'ow, in this type of myelitis, you will not have to wait long to decide as to its character. In a few days or weeks the muscles of the para- lyzed limbs will show a rapid wasting, since the muscles are undergoing atroiohy ; and this wasting is markedly progres- sive, since the change in the muscles continues to extend until a most characteristic and permanent deformity results, pro- vided that recovery does not occur. This condition of the cord is frequently associated with sclerosis of the lateral columns ; hence, it is not infrequent to observe a state of contraction in the paralyzed muscles, which lasts in a varying degree, until the atrophy of the contractured muscles destroys their power of producing deformity. These contractions are not inevitably permanent, if present in the Fig. Vlo.— Atropine spinal paralysis, uith contracture. (Hammond.) early stages of the disease, as they may totally disappear in t exceptional cases ; but they usually return with increased deformity as the disease progresses. In those cases of so-called 'infantile spinal paralysis," and in similar cases affecting the adult, a non-febrile "cariety of this affection may be met with, where the disease begins with no initial symptoms, but where the paralysis and all subse- quent symptoms mentioned above are developed suddenly. 334 THE SPINAL CORD. The chronic form of myelitis of the anterior horns is sel- dom to be diagnosed from progressive muscular atrophy.- It is claimed that the severe neuralgic pains which accompany the wasting process of the former are diagnostic between the two affections, and that the degeneration of the affected parts does not assume ih^ fibrillary oix fascicular character of true progressive atrophy, dependent upon changes confined to the ganglion cells of the spinal cord, but the distinction is, in my experience, a difficult one. The condition of polio-myelitis tends, as a rule, to progress upward along the spinal cord, and thus often reaches the me- dulla oblongata. The symptoms which are then produced in- clude those of paralysis and atrophy of the tongue, difficult deglutition, impairment of speech, and a nasal quality of the voice, due to the paralysis of the soft palate. The expression of the face is greatly altered by paralysis of the orbicularis oris muscle, which creates an apparent increase in the width of the mouth ; and, after laughing or weeping, the mouth re- mains open for an unusual period, and thus favors the escape of saliva. PKOGRESSIVE MUSCULAR ATROPHY (DEGENERATION OF THE GAN- GLION CELLS OF TIEE ANTERIOR HORNS). Degeneration of the ganglion cells of the anterior horns of the cord is pathologically distinguished from the condition just described, since the results of the former were of an inflam- matory character, while the latter is a purely degenerative process of primary origin. The former was rapid in its effects ; this disease is slow, since the ganglion cells undergo molecular disintegration. We may expect to find, at the autopsy of such a case, the cells changed into a granular condition, and more or less destroj^ed ; while, in extreme cases, the anterior horns of gray matter of the affected pai*t may be utterly destitute of these cells. It is this pathological change that creates the train of symptoms called '* progressive muscular atrophy." The mus- cles, supplied by nerves connected with the seat of degener- PROGRESSIVE MUSCULAR ATROPHY. 335 ation, begin to show a slowly developing atrophy of certain fibers or bundles, while other parts of the muscle may ap- pear perfectly normal ; thus it may take months for an entire muscle to become completely wasted, the muscle showing during its con- traction the gradual atrophy of cer- tain parts. This disease seems to exist most commonly in the muscles of the hand, thighs, and chest, and a symme- try ' in its development is a character- istic feature. It is seldom associated with any sensory symptoms. In the rarest cases will you be able to detect the existence of pain ; " and symptoms of anaesthesia are wholly absent. An- other point which will assist you in diagnosis is the absence of paralysis ; although the affected muscles may show a loss of power in proportion to the ac- tual destruction of muscular tissue. If you apply the faradic current to the affected muscles, you will find that they respond to its influence in exact pro- portion to the extent of the degenera- tion, so that the unaffected fasciculi will be thrown into contraction. This is in marked contrast to the effect of the faradic current ux)on the muscles in the case of myelitis of the anterior horns, where the muscles failed to re- spond in their entirety, even before they shovf ed any evidence of atrophy. The muscles which are undergoing the early changes of Fig. 124. — Progressive mus- cular atrophy of upper extremity. (Hammond.) ' The atrophy affects parts which are not only symmetrical, but homologous. It is common to see both shoulders simultaneously atrophied, or the arms and thighs, or the forearms and the legs. 2 Hammond states that pain is perceived after exertion, but he attributes it to muscular fatio-ue rather than to central causes. 336 THE SPIXAL CORD. this wasting are the seat of what are called fibrillary contrac- tions ^ These are produced by the involuntary rapid contrac- FiG. 125. — Progressive muscular atropJiy. Age of patient^ forty-Jive yean reich.) (From Fried- tions of fasciculi of fibers in a muscle. Sometimes a patieni is covered with them. Some years ago, these fibrillary con- tractions were held to be pathognomonic, but I can assure you that this is not so, as they may be observed in lead palsy, * These peculiar twitchings give the appearance of something alive being underneath the skin. Hammond states that " they can always be excited by a smart tap of the fin- ger upon the atrophied muscle." PEOGRESSIVE MUSCULAR ATROPHY. 337 in conditions of neurasthenia, and in simple paralysis. In- deed, many years ago Professor Schiff, now of Geneva, showed rhat muscles separated from their motor nerves were prone to .show fibrillary contractions. The hall of the tliumh is often the starting-point of this disease. For some reason, the muscles of the foot are not af- fected in the same proportion in those cases where the lower extremity is involved as the hand is in cases affecting the ux)per extremity. In some instances, every muscle in a region l)ut one may be atrophied, and that one seem to remain per- fectly normal. If you use a surface thermometer, you will generally detect a fall of temperature over the affected mus- cles.' A¥hen the respiratory muscles become involved, death may be produced from imperfect performance of that func- tion. The disease seems to affect males rather than females, and to be most frequent during middle life. It is sometimes associated with a congenital predisposition.'* The muscles of the thigh are frequently affected with atrophy, following degeneration of the ganglion cells of the anterior horns of the spinal gray matter. This causes not only a very marked deformity (since the calf may even ex- ceed the thigh in its circumference), but a peculiarity of gait is thus produced which differs from those described in con- nection with locomotor ataxia, tetanoid paraplegia, and paresis. If the extensor muscles, which are situated upon its an- terior portion, are atrophied, the foot can not be carried for- ward in the normal manner, if at all ; while the leg and foot can not be raised, if the flexor muscles of the knee joint be impaired by an atrophy confined to the posterior aspect of the thigh, thus compelling the psoas and iliacus muscles to lift the weight of the entu-e upper extremity by using the pelvis as a fixed point. ^ Hammond reports this fall in temperature as often reaching five degrees below the normal standard. " See the careful investigations made by Hammond, and reported by him in his excel- lent work, " A Treatise on the Diseases of the Nervous System." New York : D. Apple- ton & Co., 1876. 338 THE SPINAI^ CORD. Distortions of the affected members often accompany the condition of progressive muscular atrophy. These are to be accounted for by the fact that a simultaneous impairment of all the muscles seldom occurs, and those antagonistic to the ones affected tend to produce an abnormality of attitude in the part upon which they both acted in health. CENTRAL MYELITIS. Among the diseases of the kinesodic system may be men- tioned the condition known as "central myelitis." In this affection, the gray matter of the cord is the seat of a chronic type of inflammation in its central portion ; hence, it may involve either the kinesodic or the sesthesodic system. The inflammatory process may extend to the anterior horns, or may create compression of the cord, in almost any portion, by the exudation which results. The symptoms of this disease must, therefore, of necessity, vary with the seat of the patho- logical changes, and, in some cases, be very obscure and appa- rently confusing to the diagnostician. We may have the man- ifestations confined, for a time, to the sensory nerves, possibly accompanied by pain, numbness, anaesthesia, formication, etc. Gradually certain manifestations will appear in the motor nerves, and paralysis of certain muscles and possible atrophy may be developed. The reflex action may be increased in some parts and diminished in others, according to the portion of the gray matter involved ; bed-sores and paralysis of the bladder and rectum may be present in some cases, and absent in others ; the legs may be anaesthetic, and at the same time paralyzed ; so may the arms, without the legs, or both may be thus affected ; certain parts may have the tetanoid condition described in a previous portion of this lecture ; and, in fact, every known combination of sensory and motor symptoms may be present, complicated or uncomplicated by the evi- dences of muscular rigidity. You can thus understand that the disease is seldom recognized in its early stage, and, as it often takes years to reach a full development, an abundant opportunity will generally be afforded you for a careful and NON-SYSTEMATIC, OR ''FOCAL'' LESIONS. 339 close analysis of the symptoms which are successively brought to your notice/ "XON-SYSTEMATIC" OR "FOCAL LESIONS" OF THE SPINAL CORD. We have now considered, in this course of lectures upon the spinal cord, those lesions which are called ''systematic," since they tend to extend upward or downward in the same column of the cord without spreading laterally ; and it now remains for us to review such points as pertain to those focal or non-systematic lesions which have been enumerated in the table of diseases of the spinal cord. It is often possible and of great practical importance to the diagnostician to tell in what region of the cord the lesion is situated, and to estimate the height to which it has progressed. Of course, this is much easier in focal lesions than in the systematic, since the different columns of the cord can then simultaneously fur- nish symptoms which can be compared, and thus aid in the diagnosis. If you will look again at the table, "" to which I some time ago directed your attention, you will perceive that the focal lesions include traumatisms (of all forms) ; compres- sion of the cord (chiefly by bone and tumors) ; transverse scle- rosis of the cord ; transverse softening of the cord ; haemor- rhage into the substance of the cord ; and, finally, certain tumors which involve the cord itself. There are many other causes which might excite some local lesion, but these are the ones which will most frequently come under the notice of the practitioner. Before we begin the study of the symptoms produced by lesions at different heights in the spinal cord, it may be well to glance hastily at the drawing which I have made for YOU upon the blackboard, copied from one made by Seguin from the text of Malgaigne, which is so simple and diagram- ' The valuable contributions of Hallopeau, in the " Archives Generales de Medecine," IS'72, added much to the knowledge of this obscure affection. Schiippel, Westphal, and Leyden have also been prominent as investigators of this rather rare form of disease. "^ See page 3 1 5 of this volume. 340 THE SPINAL CORD. matic as to illustrate certain points of great clinical value and importance. Now, if you will look at this diagram, you will perceive that the line upon the left represents the different levels of Medulla. c «i J— y Us a Axis. <^ 8dC. V. <; (ith 0. Y. <( Tth C V. ^ 2d D. V. <^ nth D V. <; 12th D. V. ^ 1 L V. <^ 2 L. V. <^ Hypo-glossal N. Pneumogastric N. Phrenic N. Brachial plexus. Ulnar nerve. Crural N. Sciatic N. Fig. 126. — A diagram shovnng the relation of the spinous processes of the vertchrce to the spinal nerves and spinal cord. (Malgaigne and Seguin.) the spines of the vertebrae, and that the special points in the cord, as well as the points of origin of certain of the more im- portant nerves, are likewise shown. You will observe that the hypo-glossal and the pneumogastric nerves arise from the medulla, which lies above the level of the axis ; ' that the phrenic arises on a level with the spine of the axis ; that the brachial plexus and the ulnar nerve are connected with the * This drawing illustrates the fact that the spines of the respective vertebrae do not always correspond to the level of the nerves which escape from between their pedicles. FOCAL LESIONS OF THE SPINAL CORD. 341 cord in the region of the neck (third to sixth cervical spines) ; that the cilio-spinal center is situated between the fifth cervi- cal and the second dorsal vertebrse ; that the lumbar enlarge- ment of the cord gives otf the crural and sciatic nerves at (liiferent points, and that the space between the eleventh dor- sal and the second lumbar spines includes the point of origin of both ; finally, that the spinal cord ends at the second lum- bar spine, although the nerves continue to escape from the spinal canal much below that point. Such a diagram will prove of constant service to you, in following the discussion of the symptoms of focal lesions situated at different heights within the spinal cord. We have already studied the effects of systematic lesions, both of the kinesodic and sesthesodic systems, and have noticed how perfectly the physiology of the spinal cord is confirmed by lesions affecting the anterior or posterior por- tions of the cord separately. We are now to investigate tliose lesions which, by extending in a transverse direction, are liable to be accompanied by symptoms referable to both the sensory and motor portions of the cord. Of course, the 8ymx)toms will be modified by the extent of the lesion in a transverse direction, so that they may be mostly sensory or motor ; but the presence of both sensory and motor symp- toms is strongly diagnostic of focal lesions^ irrespective of a predominence of either, and is never produced by any sys- tematic lesion of the cord, with the one exception of central myelitis. We will start with a general statement, as a guide in our study of focal lesions, which is as follows : focal lesions usu- ally give rise to ^araZ^/^?^ of motion, to an alteration in the reflex excitability of the cord (usually an increase), and to more or less ancestJiesia, numbness, and pain; the bladder and rectum are often paralyzed, and a tendency to bed-sores is frequently produced. The first two of these effects, and also the last, are due to alteration in the kinesodic system ; the remaining ones are the result of some disturbance to the cGsthesodic system. 24 342 THE SPINAL CORD, In studying focal lesions situated in different regions of the spinal cord, we must adopt some system, if we expect to grasp the fine distinctions which can be drawn between the results of lesions of the upper cervical region, the cervical en- largement, the mid-dorsal region, the region just above the lumbar enlargement, and, finally, the lumbar enlargement itself. Most of these distinctions depend upon certain ana- tomical points, which your previous drill will enable you to appreciate more easily than if your anatomical knowledge had become deficient from a lack of review. FOCAL LESIOI^ IN THE UPPER CERVICAL REGION. In this condition, hemiplegia will be produced if one lat- eral half of the cord be alone affected, while paraplegia will be present if the lesion extends transversely to both lateral halves of the cord. The hemiplegia or paraplegia will be complete below the head, and the entire body may be rendered anaes- thetic. Since the phrenic nerve arises at this point, the act of respiration will be interfered with, creating dyspnoea and hic- cough ; but the respiration will not be arrested, since the pneumogastric nerves continue to excite it, and the auxiliary muscles of respiration can expand the chest without the action of the diaphragm. Should the lesion be a surgical one (as it usually is), the respiraiory center of the medulla may be af- fected, and death take place from asphyxia ; but I do not think such a result can be explained as a simple effect of pa- ralysis of the phrenic nerves alone. The presence of the cilio- spinal center in the lower cervical region may cause the pu- pils to show an irregularity, and the face and neck may mani- fest a marked increase of temperature.' The pulse may b(^ rendered variable, from irritation of or pressure upon the ac- celeratory center of the heart. Now, as I have before said, this type of lesion is almost al- ways a surgical one, comprising pressure from fracture, dislo- cation, caries, tumors of the vertebrae, etc., and these cases ' Sec page 134 of this volume for effects of blood-vessels upon tbe iris ; and also pap 185 for the evidences of diminished iritic reflex. FOCAL LESIONS OF THE CERVICAL REGION. 343 seldom live long enough for us to study the effects of such a lesion with much detail. In those rare instances where the lesion is non- traumatic and slowly developed, the effects of irritation have been shown in a hiccough (probably due to irritation of the phrenic nerve), acceleration of the pulse (from irritation of the acceleratory center of the heart), and dyspnoea (from some interference with the phrenic nerve or the nucleus of the pneumogastric nerve in the medulla) ; while the paralysis has first appeared as a paretic condition of the arms, then of the chest, and, finally, of the lower limbs. FOCAL LESION^S OF THE CERVICAL EKLARGEMEN^T. This type of lesion differs in its effects, if developed sud- denly or gradually, and also when situated in the upper or the lower part of the enlargement. If the lesion be so situated as to create only irritation of the cilio-spinal center, or the ac- (^eleratory center for the heart (both of which are in that vicin- ity), the effects will differ from those due to actual pressure upon or destruction of those centers.' In the first instance, the pupils will usually be dilated and the face pale, while t lie heart will be accelerated ; in the latter, the pupils will generally be contracted, the face and neck flushed, and the pulse retarded. The effects will also differ if the lesion affects l)oth lateral halves of the cord or only one. Wherever the lesion be situated within the cervical enlarge- ment, the arms and legs will gradually become paralyzed ; the arms and hands usually becoming first numb and paretic, and the lower limbs exhibiting, for some time, only a sense of weakness and evidences of an increased reflex excitability. A sense of constriction around the chest (the so-called '' cinc- ture feeling") is generally present, the seat of which varies with that of the exciting lesion. When the lesion is situated at the upper part of the en- largement, the motor and sensory symptoms will be manifest- ed in the lower extremities, the trunk, and in nearly all the \ The reader is referred to the pages on the third cranial and pneumogastric nerves 1 details as to the effects upon the eye or heart. 344 THE SPINAL CORD. regions of the upper extremities. The constricting band around the thorax is referred to the level of tJce clavicles^ and dyspnoea is often excessive. If you will look at the diagrammatic cut, ' you will perceive that the brachial plexus is marked as asso- ciated with the upper part of the cervical enlargement, and the ulnar nerve with the lower part ; hence the paralysis of the arms in this case would naturally be manifested in almost all of the regions of the upper extremity, and also in those parts supplied by the brachial plexus above the clavicle. If the lesion be situated in the lower part of the cervical enlargement, the symptoms exhibited will include a loss of faradic reaction of those muscles which are supplied by th^^ ulnar nerve (rather than those of the arm and the extensors of the forearm), and atrophy of these muscles will often be developed, chiefly in the flexors of the wrist and the small muscles of the hand." The same sense of constriction (cinc- ture feeling), as experienced in most spinal lesions of a local character, will exist, but it will be referred to the upper part of the chest. A paralytic condition of the muscles of the trunk (the intercostals, triangularis sterni, and the accessory muscles of respiration), as well as of the abdominal muscles, will be detected in severe cases, rendering both inspiration and expiration embarrassed, and thus adding to the danger to life. The lower limbs may exhibit evidences of numbness, anaesthesia, paresis, or complete paralysis, depending upon the extent of the lesion and the destruction done to the tis- sues of the cord. A condition of paralysis may also exist in the upper extremity. In surgical injuries to the upper portion of the cord, a peculiarity is often noticed in the temperature of the body, which is sometimes greatly elevated. This clinical feature may be associated with a marked retardation of the action ol the heart (apparently confirming the situation of an accelera- tory center for that organ in the spinal cord). ' See page 340 of this volume. ' The reader is referred to subsequent pages for the symptoms of ulnar paralysis. FOCAL LESIONS IN THE DORSAL REGION. 345 FOCAL LESIONS OF THE MID-DORSAL REGION OF THE SPINAL CORD. In the early stages of this condition the lower limbs be- come paretic, and a condition of increased reflex excitability is manifested by a rigidity and stiffness of the impaired mus- cles whenever the patient attempts to stand or walk. As the disease progresses, the muscles become paralyzed and contrac- tnred ' (probably on account of changes of a secondary char- acter in the lateral columns of the cord). In some cases, the reflex movements assume the type of spasms, so as to exhibit both tonic and clonic contractions. It was this symptom which suggested to Brown- Sequard the name of "- spinal epi- lepsy," since it occurs when the patient is exposed to the slightest peripheral irritation, and often when in the recum- bent posture.^ The sense of constriction around the body is referred to the region of the navel, or that of the lower ribs, or possibly as high as the axilla, since it may be taken as a relative guide to the highest limit of the lesion. A peculiarity exists in this condition as regards the bladder and the rec- tum ; although they may be paralyzed, they are often enabled by the aid of reflex action to expel their contents, thus appar- ently having regained their function. In the early stages, the urine and fseces may be too hastily expelled for the comfort of the patient, often compelling the performance of either act before a proper place can be reached ; but, in the advanced stages, the urine is retained to such an extent as to cause an "overflow," which is often mistaken for an actual inconti- nence,' since a constant dribbling is present. This symptom is always an indication for the regular use of a catheter. The sexual function seems to be often unimpaired, as coition is frequently possible. It is seldom that the paralyzed muscles ('xhibit a tendency to atrophy, and the electrical reaction of ^ A term used in contradistinction to the word "contracted," to designate a perma- nent shortening rather than a temporary response to a motor impulse. ^ The presence of urine in the bladder or of faeces in the rectum may often create these spasms. ^ For the diagnosis between these two conditions, the reader is referred to " A Prac- Tical Treatise on Surgical Diagnosis," by the author. William Wood & Co., New York, 1S80. 346 TEE SPINAL CORD. the affected parts is either normal or exaggerated. The chief seat of weakness is usually detected first in the feet, and the paralysis gradually involves the entire lower limbs. FOCAL LESIONS ABOVE THE LUMBAR ENLARGEMENT OF THE SPINAL CORD. In this situation, a focal lesion of the cord produces about the same sensory and motor symptoms as those described in connection with a lesion of the mid-dorsal region, with the exception that the reflex spasms^ present in the paralyzed muscles, are perhaps somewhat less violent than when the lesion is higher up the cord. These tonic and clonic spasms are, however, sufficiently well marked to constitute a promi- nent symptom,* and they indicate an increased reflex excita- bility of the gray matter of the cord below the seat of the lesion. An ingenious explanation of this increased reflex has been advanced by Professor Seguin of this city, which seems to merit respectful consideration. I quote from a late paper* of his upon affections of the spinal cord, as follows : "The classic theory of the physiology of contracture in hemiplegia is that it is due to the secondary degeneration — i, e.y actively caused by the lesion of the posterolateral col- umn. Seven years ago (see ''Archives of Scientific and Prac- tical Medicine," vol. i, p. 106, 1873) I rejected this hypothesis, and suggested a different one, which I have since elaborated and taught in my clinical lectures at the College of Physicians and Surgeons, New York. This hypothesis, which I intend shortly to publish in detail, is briefly that the spasm is due, not to direct irritation from the sclerosed (?) tissue in the postero-lateral column, but to the cutting off of the cerebral influence by the primary lesion, and the consequent prepon- derance of the proper or automatic spinal action — an action which is mainly reflex. This theory explains the phenomena observed in cases of primary spinal diseases with descending degeneration, and can be reconciled with results of experi- ' These reflex spasms have been called by Brown-S6quard " spinal epilepsy," * " Annals of Anatomical and Surgical Society," Brooklyn, December, 1880. FOCAL LESIONS OF THE LUMBAR REGION. 347 ments on animals (increased reflex power of spinal cord after a section high up, Brown- Sequard ; inhibitory power of the encephalon on the spinal cord, Setchenow)." The urinary and rectal organs are affected in about the same way as in lesions of the dorsal region. Coition is often possible, and erections are normally frequent. The rectum is paralyzed, as a rule, and constipation is usually present on that account. Micturition becomes slow and interrupted, as the bladder grows paretic, and retention and overflow are produced later on in the disease. The paralysis of the extremities is first noticed in the feet, which have long before exhibited a sense of weakness and easy fatigue. Numbness and anaesthesia usually accompany the motor paralysis, and extend as high as the groin or the waist. The sense of a constricting band around the body is present here, as in lesions of other localities, and is referred to the waist, below the level of the umbilicus, or at the level of the hips. FOCAL LESIOJ^S OF THE LUMBAR ENLARGE3IENT. If you will look at the diagram of the spinal cord upon the blackboard, ' you will perceive that the lower portion of the lumbar enlargement is represented as giving origin to the sciatic nerve ; hence, it is reasonable to expect that a lesion situated in the lower part of this enlargement would be mani- fested by symptoms of an incomplete paraplegia, in which the muscles supplied by the sciatic nerves would be the most affected.' Now, this fact seems to be confirmed by clinical experience, since the feet, legs, posterior aspect of the thighs, and the region of the nates are chiefly paralyzed when the le- sion is so situated. The bladder is unaffected, but the sphinc- ter ani muscle is often rendered paretic, or it may be entirely paralyzed. The portions of the limbs which are to become the seat of paralysis usually exhibit a sense of numbness before the effects of the lesion are fully developed, and, in case the ^ The reader is referred to the figure on page 340 of this volume. "^ The reader is referred to the pages which treat of the clinical points pertaining to the sciatic nerve, for the symptoms of this type of paralysis. 348 THE SPINAL CORD. posterior columns of the cord be involved, complete anaesthe- sia may also exist in the parts supplied with motor power by the sciatic nerve. The condition of the paralyzed muscles, as to their electrical reactions, and the presence or absence of the evidences of increased reflex excitability will depend greatly upon how much damage has been done to the gray matter of the lumbar enlargement. If the gray matter be so destroyed as to impair its function, the reflex movements will be absent ; and, if the trophic function of the cord be afl'ected by changes in the ganglion cells of the gray matter, the para- lyzed muscles will undergo atrophy. The sense of constric- tion, or ''band feeling," will usually be referred, in this le- sion* either to the ankle, leg, or thigh. FOCAL LESIONS CONFINED TO THE LATERAL HALF OF THE SPINAL CORD. In discussing the focal lesions of the cord, we have de- scribed the clinical points which are afforded by destruction, to a greater or less extent, of the substance of the cord in both of its lateral halves ; hence, the motor and sensory symptoms have been usually referred to both sides of the body. It was necessary to thus describe them, since focal lesions, unless traumatic, are seldom confined to one lateral half of the cord ; but, in some cases which may be presented to your notice, where a tumor, a fractured vertebra, a haemorrhage, a severe contusion, or some other localized lesion exists, the injury done to the spinal cord may be confined exclusively to one lateral half, resulting in one of two named conditions, viz., "spinal hemiplegia" and "hemi-paraplegia." Before proceeding to the special consideration of either of these conditions, it may prove of advantage to review some few points in the physiology of the cord, and to again direct your attention to the two plates upon the blackboard, which are already familiar to you. This plate ' shows you that any lesion of a lateral Jtalf of the spinal cord must produce anaesthesia in the opposite side of the body, since all the sensory nerves decussate and enter ' See Fijr. 120 of this volume. FOCAL LESION OF A LATERAL HALF OF THE CORD. 349 the gray matter of the cord, which serves as a condiictino- medium for sensory impressions, while the motor symptoms produced by the same lesion must be confined to the same Hide of the body as the lesion^ since no decussation probably occurs in the spinal cord (these fibers decussating only in the medulla oblongata). This second diagram' will further MS S M :\- ^t assist you to appreciate the fact that lateral lesions, as well as those which aifect the entire cord, are modified, as regards their symptomatology, by the height of the lesion in the cord ; since the motor nerves, and the special cen- ters which are situated in the cord itself, will only be affected when they lie below the seat of the lesion or are directly in- volved in the destructive process. It wil], therefore, be unnecessary to enter again into detail as to the full bearings of the plate, since they are probably fresh in your memory. When the focal lesion is placed high :ip in the substance of the spinal cord, the motor paralysis affects one side only of the body (provided the lesion is confined to a lateral half), and the term " spinal hemiplegia " is applied to this form of paral- ysis in contradistinction to a hemiplegia of cerebral origin. If the spinal lesion be situated in the dorsal region and be con- fined to the lateral half of the cord, a motor paralysis of one half of the same side of the body below the seat of the lesion is developed, a condition to which the term " hemi-paraple- gia " is commonly applied. In closing the clinical aspects of lesions of the spinal cord, it will be necessary, therefore, for us to consider the essential features of these two remaining conditions. \M Fig. 127. — A diagram to show the course of the motor and sensory paths in the spinal cord. (Brown-Sequard.) D, decussation of pyramids ; M, motor paths ; S, sen- sory paths. ' The reader is referred to page 307 of this vohime for details as to the utility of this figure in the study of spinal affections. 350 THE SPINAL CORD. SPINAL HEMIPLEGIA. In order to produce a typical case of this condition, it is necessary to have a lateral focal lesion of the cord in its upper- most part (in or above the cervical enlargement of the cord). If we suppose, then, that such a lesion be present, let us see what we might reasonably expect, on purely physiological grounds, would be the result. AVe can then examine the clinical rec- Medulla. Axis. <^ dC. V. < I ^ 6th C. V. / ^1 J Tth C V. <( 2d D. V. <^ 11th D. V. <[ 12th D. V. <^ 1 L. v. <^ 2 L. V. <^ Hypo-glossal N. rncumogastric N. Phrenic N. Brachial plexus. Ulnar nerve. Crural N. Sciatic N. Fig. 128. — A diagram to show the relation of the spinous p'occsscs of the veriebrce to spi- nal nerves. (Malgaigne ' and Seguin.) ords of such cases, and either confirm our deductions or gain some additional information. Such a lesion would, in the first place, shut off all motor impulses sent out from the brain to parts below the lesion, on the same side as the lesion, since ' " Trait6 d' Anatomic Chirnrgicale." i SPINAL HEMIPLEGIA. 35X the decussation of the motor fibers has already taken place in the medulla ; hence motor paralysis should, theoretically, oc- cur in the arm and leg of the side of the body corresponding to the seat of the exciting lesion, and the trunk should also be i)aralyzed upon that side. This we find, clinically, to be true,' with the exception that the intercostal nerves often retain their motor power when the nerves of the arm and leg are no longer capable of carrying motor impulses. In the second place, we should expect to find that the sensation of the side of the body opposite to the seat of the lesion would be de- stroyed or greatly impaired, since the sensory nerves decus- sate throughout the entire length of the cord. This we also find confirmed by clinical facts ; and so perfect is this ansesthesia that the line can often be traced to the mesial line of the body exactly, and upward to the limit of the exciting lesion. In the third place, the situation of the cilio-spinal center in the cervical region of the cord would naturally suggest some effects ux)on the pupil,' and the circulation and temperature of the face, neck, and ear of the same side. This is also confirmed, as the pupil does not respond to light, but it still acts in the ac- commodation of vision for near objects, and the skin of the regions named becomes red and raised in temperature. Fi- nally, the presence of "caso-motor centers in the cord might occasion a rise in temperature in the paralyzed muscles ; and, strangely confirmatory of this fact, we often find the tempera- ture of the paralyzed side of the body hotter than that of the anaesthetic side. In some exceptional cases, the face, arm, and trunk are alone paralyzed, the legs seeming to escape, and often giving evidence of reflex spasm (perhaps most commonly on the ansesthetic side). This must be explained as the result of incomplete destruction of the lateral half of the cord. ^ThG researches of Brown-Sequard, as early as 1849, and his published memoirs (1863-'5 and 1868, 18G9), have probably done more to clear up this field and to place it upon a positive foundation than those of any other observer. 2 The reader is referred to pages 114 and 135 of this volume. 352 THE SPINAL CORD. HEMI-PARAPLEGI A. This condition is the result of some focal lesion of the spinal cord in the dorsal region, which involves only its lateral half. The results of such a lesion differ but little from those of one causing spinal hemiplegia, as regards the motor and sensory symptoms, excepting that the situation of the excit- ing cause is below the cervical enlargement, where the nerves to the upper extremity are given off, and where the cilio- spinal center is situated. For that reason the muscles of the upper extremity are not paralyzed, nor are the effects upon the pupil and the skin of the face, ear, and neck (mentioned as present in spinal hemiplegia) produced. The muscles be- low the seat of the lesion are paralyzed on the side of the body corresponding to the exciting cause, and the skin is sometimes rendered hypersesthesic upon that side ; * while the integu- ment of the side opposite to the lesion is deprived of sensi- bility. The bladder and rectum may be paralyzed in some instances. The sense of constriction, or ''band feeling," will vary with the seat of disease in the spinal cord. The aipount of reflex irritdbility and the presence or absence of muscular atrophy in the parts paralyzed will depend upon the depth of the lesion in the spinal cord and the changes which have been produced in the gray matter. The same increase of tem- perature in the paralyzed limb, which was mentioned as oc- curring in spinal hemiplegia, may also be present in this vari- ety of paralysis. Should the side affected with anaesthesia give any evidence of motor paralysis or muscular weakness, or symptoms of anaesthesia appear upon the side where the motor paralysis is present, you may regard either one as conclusive evidence that the exciting lesion is progressing, and that the opposite lateral half of the cord is being involved to a greater or less extent. ' This is probably due to some irritation of the gi*ay matter of the cord. ♦ THE SPmAL SERVES. THEIR ORIGIN, DISTRIBUTION, FUNCTIONS, AND CLINICAL IMPORTANCE. THE SPIISrAL I^EEYES. We have now considered the general points in the con- struction of the cerebro-spinal axis, and the clinical facts which pertain to the brain and spinal cord. We have also separately discussed those nerves which are connected with the brain, and have noted all the peculiarities in their distri- bution and anastomoses, which seem to shed a light upon their physiological action or the clinical features which each of them presents. It now remains for us to investigate those nerves of the neck, trunk, and the extremities which are con- nected with the spinal cord, and are called "spinal nerves," in contradistinction from the nerves of cranial origin, or those of the sympathetic. The spinal nerves comprise thirty-one pairs, which escape from each side of the spinal cord by two roots, called the anterior or ''motor root," and the posterior or "sensory root." These two roots join with each other, in every in- stance, to form one nerve, which is named in accordance with its situation and the region of the vertebral column from which it escapes ; since the nerves, so formed, pass through foramina between the pedicles of the vertebrse, throughout the entire length of the spinal column. Thus we have eight pairs of cervical nerves^ escaping upon either side of the cervical vertebrae ; twelve pairs of dorsal nerves^ bearing the same relation to the dorsal region of the spine ; five pairs of lumbar nerves on each side ; five pairs of sacral nerves^ 356 THE SPINAL NERVES. escaping from the foramina of that bone ; and one pair of coccygeal nerves. As mentioned in the lectures upon the construction of the spinal cord, the anterior roots of the spinal nerves ■ ^- Anterior "fl branch of 3d Cervical nerve. a w Anterior branch of 4th Cervical nerve. Sttperficial branches (integument- ary;. Ascending set, Occipitalis minor Filament to attollens aurem. Auricularis mafjnua. Superficlalis colli Branch to platysma. Descending ! ( ( Sternal, < Supra-clavicu'ar bninches.-< Clavicular, ( ( Acromial. Deep BRANCnES. Internal set. I. External set. 1 Pneumosrastric, Communicating.'-? Hypo-glossal, / Sympathetic. I Kect. cap. ant. major. Muscular -^ Kect. cap. ant. minor, { Rect. cap. lateralis. Comtvvnicans noni. |_ Phrenic. {Sterno-mastoid, Levator anguli scapulae, Trapozms, Scalenus med. Communicating with spinal accessory nerve. The table which illustrates the method of construction of the cervical plexus and its branches of distribution may be ' See page 276 of this volume. 2 The loop between the first and second cervical nerves usually gives off the communi- cating branches to pneumogastric and hypo-glossal nerves and to the superior cervical ganglion of the sympathetic, while the third and fourth cervical nerves give communicat ing branches to the main cord of the sympathetic nerve. I THE CERVICAL PLEXUS OF NERVES. 365 studied with some advantage. It will be seen tliat the plexus gives off two distinct sets of branches, called the superficial •nd the deep, since the former, as the name indicates, are all Fig. 133. — Superficial branches of the cer^vical plexus. (Hirschfeld.) 1, superficialis colli ; 2, 2, its descending branches ; 3, its ascending branches ; 4, filaments of anastomosis with the facial ; 5, auviculai-is magnus ; 0, its parotid branch ; 7, its external auricular branch; 8, upper part of the same branch, crossing the fibrous tissue which surrounds the root of the helix, and supplying the external surface of the pinna; 9, internal auricular branch; 1<», filament of anastomosis between this branch and the posterior auricular of the facial ; 11, occipitalis minor; 12, branch of communication with the occipitalis major ; 13, accessory occipitalis minor ; 14, branches to the integument on the back of the neck; 15, supra-clavicular branches, sternal portion; 16, clavicular portion; IT, supra-acromial branches, anterior division; 18, posterior division ; 19, branch to trapezius from cervical plexus ; 20, branch to tra- pezius from the spinal accessory, and anastomosing with the preceding; 21, branch to the levator anguli scapulae ;* 22, trunk of the facial ; 23, its posterior auricular branch ; 24, its cervical and mental branches. THE SPINAL NERVES. cutaneous, while the latter are distributed to muscles and ad- jacent nerves. The superficial or integumentary set comprises four nerves, three of which ascend toward the head, while the remaining one descends toward the shoulder ; the deep set is subdivided into branches which pass toward the mesial line of the trunk, the internal set, and those which pass away from the mesial line, the external set. SUPERFICIAL BRANCHES OF THE CERVICAL PLEXUS. The superficial set of branches is of the greatest impor- tance to the physician, since the symptom of pain is often a most positive guide to disease, which can be localized by a thorough knowledge of the nerves. The sub-occipital nerve Fig. 134.— The nerve supply of the posterior part of the head. (Hilton.) A, region supplied by the great occipital nerve ; B, region supplied by the small occipital nerve ; C, region supplied by the auiiculo-temporal nerve. (first cervical), the great and small occipital nerv^es (branches of the second cervical), and the auricularis magnus (a branch of the third cervical) are all distributed to the integument of the scalp^ in the posterior region of the head, covering the space which extends from the neck to the vertex of the cra- nium. The plate which I now show you w^as designed by SUPERFICIAL BRANCHES OF CERVICAL PLEXUS. 367 Hilton,' to illustrate the results of careful experiment as to the limits of the cutaneous distribution of each of these nerves. In my lecture upon the distribution of the fifth cranial nerve, I called your attention to the diagnostic value of the cutaneous distribution of the nerves of the ear. It may be Fig. 135, — The nerve supply of the posterior portioti of head and neck. (Modified from Flower.) 1, region supplied by the great occipital nerve ; 2, region supplied by the auriculo-tempo- ral nerve ; 3, region supplied by the small occipital nerve ; 4, region supplied by the great auricular nerve ; 5, region supplied by the third cervical nerve. well to again state that the integument of the pinna is sup- plied by the fifth cranial, the great auricular, the auricular branch of the great occipital, and the small occipital nerves, ' and to impress upon you that the limits of the distribution of each are now so well defined as to afford a clew, in many instances where pain is confined to this region, to the seat of the exciting cause. ^ Op. cit. ^ The auricular branch which Hilton lays stress upon, as supplying the lobule of the I r with sensation, may be given off either by the anterior or posterior division of the eond cervical nerve. In the table of the distribution of the cervical nerves I have put it down as a branch of the^rrm^ occipital nerve, since that is its most common origin ; but it, not infrequently, is found to arise from the small occipital nerve, in which case it would be derived indirectly from the anterior division of the second cervical, rather than from the posterior division. 368 THE SPIXAL NERVES. The descending branches of the superficial set of the cervi- cal plexus (supra-clavicular) arise from the third and fourtli cervical nerves, and are distributed to the integument cov- ering the lower portion of the neck and the regions of the sternum, clavicle, and acromion. The fact that the filaments of these nerves are distributed to the fascia covering tlu upper portion of the chesty below the clavicle, is made a point of diagnostic importance by Hilton, since cases of dis- ease of the spinal column, in the region of escape of the third or fourth cervical nerves, or the existence of pressure along the course of these nerves, have been suggested to him by pain in this region, and thus detected far away from the seat of pain. He says : ''As nothing but the nerves can produce pain, this simple distribution ought to remind us of the fact that, if a patient complains of pain in this part of the chest, the cause may lie in one of two directions. It may depend upon disease of the cervical region of the spine, or in connec- tion with some disease affecting the origin of the upper dorsal nerves." The cervical plexus lies upon the scalenus medius and the levator anguli scapulae muscles, and is covered by the sterno- mastoid muscle ; hence, all of its superficial branches emerge from beneath the posterior border of this latter muscle.' The muscles which the plexus supplies directly are the three which lie in contact with it and the trapezius. ]S'ow, it will be remembered that the trapezius and the stemo-mastoid muscles have another source of nervous suj^ply, viz., the spi- nal accessory nerve.' This fact suggests that these muscles must each belong to two groups : the first, those which con- trol pTionation ; ' the second, those which insure the ordinary motions of the neck. In the same way, the platysma muscle, by its nervous supply, is clearly stamped as not only a mus- cle of the neck, but also one of expression^* since the facial nerve supplies it, as well as the cervical plexus. ^ See figure on page 005 of this volume. ' See page 262 of this volume. ' See page 263, previous lecture, upon this nerve. ^ For the action of this muscle in the expression of melancholy, sec the facial nerve. COMMUmCANS NONI NERVE, 369 DEEP BRANCHES OF THE CERVICAL PLEXUS. A secoud reference to the table, in which the branches of this plexus are shown, will enable you to recall the subdivis- ion of the deep branches. The set that passes toward the mesial line of the body comprises the muscular filaments to the recti muscles, the communicating branches to adjacent nerves, and two specially named trunks, the phrenic and com- municans noni nerves ; while the set which passes toward the periphery of the neck comprises the muscular branches to the sterno-mastoid, trapezius, levator anguli scapulae, and the scalenus medius, and communicating filaments to adjacent nerves. The filaments of communication between the cervical plexus and the pneumogastric, hypo-glossal, spinal accessory, fifth cranial, and sympathetic nerves, have been already dis- cussed in connection with each of these nerves. They all in- dicate some definite purpose on the part of Nature, and can best be reviewed by a careful perusal of the notes taken by you in the early part of this course of lectures. ' Many of the diagrams of the special nerves mentioned will make points clear to you which it is useless to repeat. The communicans noni nerve, whose origin can be traced to two filaments connected with the second and third cervical nerves, is of surgical interest from the relation which it bears to the sheath of the carotid artery ; and the branches which are given off from the loop, formed by its junction with the descendens noni nerve, can be seen by referring to the dia- gram of the hypo-glossal nerve." Occasionally this nerve is found to enter the sheath of the carotid artery, and to anasto- mose with the descendens noni nerve in this abnormal situa- ^ For the association between the fifth cranial nerve and the second cervical in the in- tegumentary supply of the ear, see page 157 ; between the facial nerve and cervical nerves, see page 186 ; between the pneumogastric nerve and the arcade formed by the first and second cervical nerves, see diagram of pneumogastric on page 238 ; between the si)inal accessory nerve and the upper cervical nerves and its physiological bearing, see pages 262 and 267 ; finally, between the hypo-glossal nerve and the communicans noni nerve, see plate on page 275 of this volume. ^ See page 275 of this volume. 370 THE SPINAL NERVES. tion.' From the loop which it helps to form, filaments are given to the stemo -thyroid, sterno-hyoid, and both bellies of the omo-hyoid muscle. Thus these muscles are placed under the control of two nerves ; the one (communicans noni nerve) enabling them to act in harmony with the muscles of the neck, while the other (descendens noni nerve) enables them to assist in depressing the larynx and the hyoid bone, after the bolus of food has passed the isthmus of the fauces, thus acting in harmony with the tongue, which is also supplied by the hypo- glossal nerve. We can perceive, therefore, that these mus- cles are concerned in two distinct functions — the movements of the neck and the act of deglutition and speech ; hence they must of necessity be separately supplied by the nerves of the neck and that of the tongue, in order to properly perform the two acts independently of each other. The phrenic nerve, called also the ''internal respiratory nerve of Bell," ' arises, by three heads, from the third, fourth, and fifth cervical nerves. Its course and distribution give it a surgical as well as a physiological importance. It lies in front of the scalenus anticus muscle, and thus in relation to the second portion of the subclavian artery ; lower in the neck, it passes between the subclavian vein and the first portion of the subclavian artery ; when it has entered the superior open- ing of the chest, its course upon the left side of the body lies in front of the arch of the aorta and the pulmonary artery, but upon the right side the nerve passes between the superior vena cava and the right innominate vein ; each nerve crosses in front of the root of the corresponding lung, gives off twigs to the pericardium and pleura, and perforates the diaphragm, to be distributed to its under surface. Both nerves give fila- ments to the phrenic plexus of the sympathetic, and the right nerve furnishes some filaments to the diaphragmatic ganglion. The distribution of the phrenic nerves to the diaphragm is mentioned by Hilton' as one of the simple devices of ' It is sometimes found beneath the jugular vein, and, occasionally, in front of it. ^ This name was applied to the phrenic nerve by Bell, since it passes internally to the chest wall, and assists in the physiological act of respiration. ^ Op. cit. THE PHRENIC NERVE. 371 Nature to guard the nerves from injury. I quote from his excellent treatise as follows: "As a rule, nerves enter the muscles where they will be most secure from pressure, and it is curious to observe how careful Nature has been in this re- spect to guard one of the most important nerves in the body. The phrenic nerves (our life hangs on these threads), after })assing through the chest, traverse the diaphragm and dis- tribute their branches to the under surface of the diaphragm, and are so situated that they can not be compressed during respiration. If they were situated upon the upper surface of the diaphragm, where there is a constant and forced con- tact between the base of the lung and the superior aspect of the diaphragm, and especially so during a retained inspira- tion, it is obvious that the filaments of the phrenic nerve would, under such circumstances, be exposed or subjected to compression, and the action of the diaphragm would be dan- gerously interfered with. The nerves are, however, distrib- uted to the under or concave surface of the diaphragm ; the whole tendency of gTavitation being to remove the liver, the stomach, and the spleen away from them, so as to enable the nerves to carry on their influence to the diaphragm unmo- lested." How extraordinary is it that the phrenic nerve (a nerve so important to life) can pass through the chest between the dilated heart and the inflated lungs, and yet, as far as we know, never receive any untoward influence from pressure ! It is true that the lungs have a remarkably definite concave form toward the heart, arching over the course of the phrenic nerve ; but, when the lungs are emphysematous, it seems quite probable that these nerves might suffer from pressure, and cause some difficulty in breathing. When extravasation of air occurs from rupture of the trachea or a large bronchial tube, the patient dies rapidly from extreme shortness of l)reath ; and this can be explained by the fact that the air enters the tract of the phrenic nerve, thus causing extreme pressure and death from paralysis of the diaphragm. The distribution of the phrenic nerves to the pericardium 372 THE SPINAL NERVES. seems to warrant the supposition of Hilton that the pericardi- um may be considered as a portion of the fascial tendon of the diaphragm, since it is closely identified with it, and is acted upon by it, at all times. It may also be considered as pro])- able that the phrenic nerves are endowed with some sensor 1/ filaments,* by communication with other nerves ; and the analogy of the pericardium and diaphragm to a joint, so beau- tifully pointed out by Hilton, where the fibrous layer of the heart sac resembles the capsular ligament, the serous layer the synovial membrane, and the diaphragm the muscle whicli moves it, is confirmed by the similarity of nervous distribu- tion/ We know that in pericarditis the patients complain of a sense of constriction and tightness in the chest, and are afflicted with a shortness of breath ; we also see an inflamed condition of this membrane creating a spasm of the dia- phragm, precisely as the nerves of an inflamed joint create a contraction of the adjacent muscles ; and why are we not justified in attributing these symptoms to the analogy which anatomy so well sustains, and the axiom of nerve supply to joints seems to confirm ? CLINICAL POINTS PERTAINING TO THE CERVICAL NERVES. The distribution of the branches of the upper four cervical nerves, which have been considered in some detail in the pre- ceding lecture, may be said to furnish sensory filaments to the skin covering the occipital region as high as the vertex, and the integument of the neck, in its posterior and lateral aspects, as far down as the shoulder. The muscular fila- ments given off by these nerves have little clinical interest, since the diseases which are most frequently met are confined chiefly to the great occipital nerve, the cutaneous branches of the neck, and the phrenic. We will consider, therefore, only ' Luschka and Ilenle rcirard the phrenic as a mixed nerve. This view seems to be sustained by cases of neuralgia (as reported by Falot, Peter, Erb, and others) which have been produced by irritation of this nerve. The development of Luschka's ganglion upon this nerve seems to be a further evidence of the existence of sensory as well as motor fibers within the phrenic. ^ See axioms of nerve diitributiou, on page 359 of this volume. GERVICO-OCGIPITAL NEURALGIA. 373 that type of neuralgia which affects the regions of the occi- put and neck called " cervico-occipital neuralgia" and the nervous disorders dependent upon the distribution of the phrenic nerve. Cermco-occipital Neuralgia, — This is a rare form of dis- ease. It is induced by exposure, perhaps, more frequently than by any other cause. It may be also the result of dis- eases of the spinal column, such as periostitis, spondylitis of tlie cervical region, tumors, and injuries ; also of wounds of the nerves, irritation of the cervical portion of the spinal cord, enlarged lymphatic glands, neuromata, tumors of the neck or spinal cord, foreign bodies, etc. Aneurism of the ver- tebral artery has been known to produce it. The pain of this type of neuralgia may be continuous or [)aroxysmal, and either circumscribed or widely diffused over tlie entire occipital and cervical regions. In severe parox- ysms of pain, the movements of the head and the acts of speech and mastication may be rendered difficult or impossi- i )le. Movements of the head, and the acts of laughing, sneez- ing, and mastication, often tend to excite the paroxysms of pain.' As in many other forms of neuralgia, certain points of ex- 1 reme tenderness, the "puncta dolorosa of Yalleix," may be detected, and these may be distinctly located at the following spots : 1. Where the great occipital nerve escapes at the occiput, between the mastoid process and the first cervical vertebra. 2. Where the branches of the cervical plexus escape around the posterior border of the sterno-mastoid muscle, in t he middle point of the necJc. (This point of tenderness may be absent.) 3. Where the small occipital and great auricular nerves ''^cape to the surface, just behind the mastoid process. 4. Where the frontal branch of the trigeminus, the great auricular, and the occipital nerves meet, over the situation of the parietal protuberance. ^ The fixed attitude in which this class of patients hold their heads is very characteristic. 26 374 THE SPINAL NERVES. 5. Where the auricular nerves meet, on the concha of the ear.' It is the detection of these points of tenderness ' that as- sists the diagnostician to discriminate between rheumatic pains and those of a purely neuralgic character, and it will usually be observed that the paroxysms of pain start from these points of tenderness. This type of neuralgia is often associated with a similar affection of the fifth nerve, and occa- sionally of the brachial plexus. It may be followed by nu- tritive disturbances, such as falling out of the hair over the affected region. The duration of this form of neuralgic pain varies from a few days, to weeks, months, or even years, de- pending somewhat upon the exciting cause. DISOEDERS OF THE PHRENIC NERVE. The phrenic nerve may manifest the effects of irritation in the form of neuralgia, clonic spasm (hiccough), and tonic spasm of the diaphragm ; and also that of a more serious im- pairment of its function, as diaphragmatic paralysis. Diaphragmatic neuralgia seems to be manifested (in those few reported cases w^hich are well authenticated) by a pain which begins in the base of the thorax, at the point of insertion of the diaphragm, and which radiates upward into the territory of the shoulder and neck, which is supplied by the cutaneous branches of the cervical plexus. The points of tenderness which exist in this affection seem to be most marked (1) in the region of origin of the phrenic, near to the spinous processes of the middle three cervical vertebrae ; (2) over the nerve, as it enters the supra-clavicular fossa ; and (3) at the anterior insertions of the diaphragm, between the seventh and the tenth ribs. It is claimed by Erb that a point of tenderness can often be detected over the cartilage of the third rib, but I find it difficult to explain this symptom on ' This point of tenderness is often absent. * It will be noticed that these points of circumscribed tenderness correspond, in every instance, to the approach of some nerve or its terminal filaments to the surface of the body. The points of subdivision of a nerve trunk into its branches of distribution are often the scat of this excessive sensitiveness to pressure. DISORDERS OF THE PHRENIC NERVE, 375 anatomical grounds, although its presence in some cases seems to be proven. The pain of phrenic neuralgia is more or less continuous, since the incessant movements of the diaphragm tend to ex- cite it ; but exacerbations, of a character closely resembling distinct paroxysms, are often observed, when the pain be- comes lancinating and causes impeded respiration. The efforts of coughing, sneezing, or exertion of any kind which involves the muscles of the trunk, are rendered difficult and painful. Muscular debility and tremblings in the upper ex- tremity are sometimes present. As this type of neuralgia often accompanies organic lesions of the heart, concomitant phenomena, such as cardiac palpitation, angina pectoris, etc., may coexist. Although lohrenic neuralgia is not infrequently an inde- pendent and primary disease in the anaemic and nervous class of patients (especially after exposure to cold, dampness, etc.), still it is far more commonly met with as a concomitant affec- tion of some other disease. It is therefore always best to look for the existence of heart lesions, aneurism of the medi- astinum, Basedow's disease, angina pectoris, and diseases of the liver and of the spleen, since they may explain the phrenic symptoms and modify the prognosis. The close resemblance which this type of neuralgia has to attacks of diaphragmatic pleurisy, pericarditis, uncomplicated angina pectoris, and gastralgia, makes the situation of the diagnostic points of tenderness an important factor in the discrimination. Violent spasmodic contractions of the diaphragm, termed clonic spasTTi or '"''TiiccougJi^''^ are accompanied by an inspi- ratory sound, interrupted by a sudden spasm of the con- strictors of the glottis, and followed by a short expiration. The symptoms produced by this condition depend upon the intensity and duration of the attack. In severe cases there may be pain, embarrassment of speech, dyspnoea, and retrac- tion of the epigastric region. The causes of hiccough may be classed under three heads : 1, those of direct irritation of the 376 THE SPINAL NERVES. phrenic, as occurs in the case of mediastinal tumors, aneurism of the arch, pneumonic or pleuritic inflammation, pressure from pleuritic effusion, etc. ; 2, those of a reflex nature, as in diseases of the urinary organs, the uterus, and the intestinal tract and the liver ; the irritation of biliary or renal calculi ; irritation of the pharynx, oesophagus, and stomach ; and dis- eases of the peritonaeum ; 3, those of central origin, as occurs in hysteria, local, brain, or spinal diseases, blood poisoning (as in the fevers, cholera, dysentery, etc.), after emotional excitement, and from the general anaemia of nerve centers after haemorrhage. You can see from this list of causes that the symptom of hiccough, if occurring late in connection with any form of disease, may be a most serious symptom. Tonic spasm of the diaphragm is a rare form of disease. It has been called ^'diaphragmatic tetanus." The symptoms of this obscure affection have been developed through the ex- periments of Duchenne upon animals, and the careful obser- vations of Yalette, Fischl, Yigla, Oppolzer, Duchenne, and others upon man. The patient is at once markedly asphyxiated, the liver is displaced downward by the contracted diaphragm ; the lower half of the thorax is enlarged and rendered immovable ; the inspirations are extremely short, and the expirations are noisy and prolonged. The face shows the evidences of anxiety and cyanosis ; the pulse is slow*and diminished in volume ; and the voice is monotonous in tone, and often interrupted. Acute pains pervade the lower regions of the thorax, and shoot over the epigastrium. While one case seems to have ended fatally, all other reported cases have recovered. Paralysis of the diaphragm may occur as a symptom of hysteria, lead poisoning, the advanced stages of progressive muscular atrophy, and paralysis of the bulbar nuclei. It may be also produced by the extension of inflammation in cases of pleurisy or peritonitis, thus creating exudation or suppuration in the substance of the muscle. When this condition is fully developed, the abdominal walls are retracted during each inspiratory effort, while the THE FOUR LOWER CERVICAL NERVES. S17 lower portion of the thorax is distended ; in expiration, how- ever, the hypochondriac region, as well as the epigastric, sinks in, while the chest becomes diminished in its capacity. The respiration becomes slow and difficult, and speaking or muscular movements increase the embarrassment of this func- tion. The voice is usually enfeebled, and may be entirely lost. The liver tends to rise in the chest, during inspiration, rather than to be displaced downward into the abdomen. THE FOUR LOWER CERVICAL ITERVES. . As was the case with the four upper nerves, which escape from the cervical portion of the spinal cord, the four lower divide into anterior and posterior divisions, as soon as they escape from the spinal foramina. The anterior dimslons of each join to form the brachial plexus of nerves, which sends filaments of distribution to the neck, shoulder, upper ex- tremity, and side of the thorax. The posterior divisions do not form a plexus,* but are separately distributed to the semi- spinalis, complexus, splenius, and trapezius muscles, and then send twigs to the integument^ over these muscles, viz., over the region of the spine in the lower part of the neck. The following table ' will assist you in mastering the con- struction of the brachial plexus, and in understanding the plates of that complicated mesh- work of nerves. It may be well to remark that the diagrams of this plexus are seldom alike in the works of any two authors ; since, if they are intended to be accurate representations of the parts, they nat- urally tend to show the great dissimilarities which exist in the union of the different nerves which help to form it, while, if purely diagrammatic, no two authors would naturally fol- low the same schematic plan. Notwithstanding the dissimi- larities which exist, there are, however, points of resemblance ^ In the case of the three upper cervical nerves, an anastomosis of the posterior di- visions occurs, to which Cruveilhier applies the term " posterior cervical plexus." ' See researches of Cruveilhier, Sappey, Hirschfeld, and others. 3 Modified from tables in "The Essentials of Anatomy" (Darling and Ranney). G. P. Putnam's Sons, New York, 1880. 878 THE SPINAL NERVES. in them all, which consist in the delineation of an outer cord formed by the fifth, sixth, and seventh cervical nerves ; an inner cord formed by the eighth cervical and first dorsal nerves ; and a middle cord formed by a branch from both the outer and the inner, which subsequently unite. THE BRACHIAL PLEXUS. Anterior division of 6th Cek- vroAL f Posterior thoracic {external rei-pirntory verre of Bell) distributed to the serratus inagnus muscle. Anterior division of 6th Cer- vical nerve. Anterior division of Tth Cee- VICAL nerve. Anterior ^ division of 8tu Cer- vical nerve. Anterior division of IfeT Dor- sal nerve. J Form outer cord of Form in- ner cord of )■ BRACHIAL PLEXUS. Branches above the clavicle. Snpra-spinatus, Supra-scapu- ; i^^a-spinatus, ^^^ \ Shoulder joint. f Rhomboidei muscles (from .^tli I cervical nerve), Subclavius (from 5th and Gth I cervical nerves). Muscular (8) { g.-aleni muscles i (^Ts^/,^' ^^h, Longus colli ■) t?^^^^ ''^'": ^ { vical nerves), I Levator anguli scapula} (from (. 5th cervical nerve). ^ Communicating branch (to phrenic nerve). Branches f Internal anterior thoracic, I Internal cutaneous, From inner ' Lesser internal cutaneous cord I ( Wri8lerg\s newe), I Inner head of median nerve, [ Ulr.ar nerve. helcywthe -{ From oixter J ^^^Jf "?/" Jf '5 *?°'"""^' plftvirlP ftnrd i External cutaneous, Clavicle. cora | ^^^^^ ^^^^ ^^ m&A\!m nerve. f 1st subscapular nerve, -r, ^ ^^„^„ 2d subscapular nerve. Hor^ cord. Musculo-spiral ner l^ Circumliex nerve lerva, This table and the diagram (after Gray) shown on the next page will help to make clear the method of construction of the brachial plexus, and the main branches which are given off from its different portions. It will be perceived that the branches of distribution are subdivided into two sets : those given off above the line of the clavicle and those given off below that line. The former set, if traced, will be seen to supply the muscles of the scapular region, some of the mus- cles of the neck, the serratus magnus (a muscle of respiration), and the subclavius. The branch of communication which helps to complete the formation of the phrenic nerve is also shown to arise from the fifth cervical nerve. The branches ' The posterior cord of the brachial plexus is formed by a branch from both the inner and outer cord. THE BRACHIAL PLEXUS OF NERVES. 379 whicli are given off below the line of the clavicle are distrib- uted to the muscles of the upper extremity, and will be con- sidered in detail in subsequent tables and diagrams. 5tk Cervical. N Fasciculus FROM 4-Cerv.A/. — Communicating WITH Phrenic. Supra Scapular. OF Clavicle. Fig. 136. — A diagram of the brachial plexus audits branches. (Gray.) Varieties, more apparent than real, are frequently met with in the formation of this plexus, ' resulting from the cor- responding increase or diminution in the size of the above anastomotic branches, and of the portion of the posterior cord which is given off by the seventh cervical nerve. The poste- rior cord may be occasionally formed by the seventh cervical nerve alone ; while it may in some instances be formed by two bands, arising from the fifth and sixth nerves, without any assistance from the seventh nerve. Other variations may re- ' The dissections and paper of 11. C. Lucas upon this point (" Guy's Hospital Eeports " 18V5) and the description of this plexus by Henle seem to confirm each other as regards the abnormalities of its formation. 380 THE SPINAL NERVES, suit from the branches of the plexus being given off at a higher or lower point than usual, and also by the seventh nerve join- ing the plexus at a higher or lower level than normal. The brachial plexus, as a whole, is broad between the mid- dle and anterior scaleni muscles, at which point it lies imme- diately above the second portion of the subclavian artery ; it is contracted in size opposite the clavicle, where the outer and inner cords lie on the outer side of the third portion of the subclavian artery ; and, in the axilla, it again expands, the three cords bearing the relation to the second portion of Fig. 137. — Anterior branches of the four last cervical and the first dorsal nerves. (Ilirsch- feld.) 1, anterior branch of the fifth cervical, ordinarily united with the sixth cervical before di- viding ; 2, anterior branch of the sixth cervical ; 3, anterior branch of the seventh cervical; 4, anterior branch of the eipjhth cervical ; 5, anterior branch of xhe first dorsal; 6, origin of the subclavian nerve; 7, posterior thoracic arising from tin fifth, sixth, and seventh cervical nerves; 8, supra-scapular; 9, common trunk ol of the branches supplying the levator anguli scapulae and the rhomboidei ; 10, supei-ior subscapular; 11, anterior thoracic branches; 12, inferior subscapular: 13, long sub- scapular; 14, separate branch to the teres major; 15, circumflex nerve; 16, lesser internal cutaneous; 17, internal cutaneous ; 18, ulnar; 19, median; 20, musculo- spiral; 21, radial. the axillary artery which their names designate. Thus it will be perceived that this plexus has important surgical relations with the last two portions of the subclavian artery and the J two upper portions of the axillary artery. The terminal branches of the three cords are also in relation with the third ABNORMALITIES OF THE BRACHIAL PLEXUS. 381 portion of the axillary artery, since they almost entirely sur- round it. The preceding cut of the brachial plexus, taken from the superb anatomical Avork of Sappey, will enable you to con- FiG. 138. — Collateral branches of the brachial plexus. (Hirschfeld.) i, arcade formed by the anastomosis of the descending branch of the hypo-glossal with the internal descending branch of the cervical plexus ; 2, pneumogastric nerve ; 8, phrenic nerv e ; 4, anterior branch of the fifth cervical pair ; 5, anterior branch of the sixth cervical pair ; 6, anterior branch of the seventh cervical pair ; 7, 8, anterior branch of the eighth cervical pair and first dorsal pair ; 9, 9, branch to the subcla- vius muscle ; 10, long thoracic nerve ; 11, nerve to the pectoralis major giving off a filament to anastomose with that supplying the pectoralis minor; 12, supra-scapular nerve passing under the coracoid ligament; 18, nerve supplying the pectoralis minor muscle; 14, branch supplying the pectoralis minor muscle given oif f rom the one which supplies the pectoralis major muscle ; 15, inferior branch of the subscapularis ; 10, nerve to the teres major muscle ; 17, nerve to the latissimus dorsi muscle; 18, accessory branch of the internal cutaneous; 19, an anastomosis of this branch with the perforating branch of the second intercostal nerve ; 20, ramification of the ac- cessory branch of the internal cutaneous nerve ; 21, internal cutaneous nerve; 22, ulnar nerve ; 23, median nerve ; 24, musculo-cutaneous nerve ; 25, radial nerve. trast the diagrammatic plate of Gray ' with the actual repre- sentation of the parts under consideration. ' See page 380 of this volume. 382 THE SPINAL NERVES. COMMUNICATIONS OF THE PLEXUS. The brachial plexus communicates with the cervical plexus by a branch which joins the fourth and fifth nerves, and by one head of the phrenic nerve. It also sends filaments to the middle and inferior cermcal ganglia of the sympathetic, and, in this way, anastomoses with the corresponding filaments of the first dorsal nerve. NERVES OF THE UPPER EXTREMITY. BRANCHES OF THE OUTER CORD OF THE BRACHIAL PLEXUS.' ( (1) External anterior tho- RACIC (2) External or MIISCULO-CU- TANEOUS Pectoralis major. f Muscular branches. Anterior branch. Posterior branch. Articular branch. Branches of the OUTER CORD of the -l brachial plexus. (3) Median . . In the hand, Coraco-brachialis, Biceps, Brachialis anticus. Integument of the front of forearm, Integument of ball of thumb, Joins with the radial nerve. Integument of radial side of back of fore- arm. Joins with the radial nerve, i Joins with the external cutaneous branch (^ of the musculo-spiral nerve. ^ In fore- , To elbow joint. f Pronator radii teres, I Flexor carpi radialis, j Palmaris longus, [ Flexor sublimis digitorum. f Flexor longus pollicis, Flexor profundus digitorum (its outer half), Pronator quadratus. Muscu- lar. Anterior interosse- ous. Palmar cutane- ous. f External branch. Internal branch. i Integument of palm - Integument of the of ball thumb. Abductor pollicis, Opponens pollicis, Flexor brevis pollicis (outer head). Digital to thumb (palmar sur- face), Digital to index finger (outer side). Digital to contiguous sides of index, middle, and ring fin- gers, Filaments to the two outer lumbricales muscles. ' Modified from a table in "The Essentials of Anatomy " (Darling and Ranney). Putnam's Sons, New York, 1880. G.P. BRANCHES OF THE BRACHIAL PLEXUS. 383 BRANCHES OF THE INNER CORD OF THE BRACHIAL PLEXUS/ f (1) Internal an- I TERIOR THORAC- IC. (2) Internal cu- taneous. (3) Lesser in- ternal CUTA- NEOUS. (VVris- bercc.) Anterior branch. Posterior branch. Branches of the INNER cord of the brachial plexus. (4) Ulnar. Both pectoral muscles (since its filaments lie above and underneath the pectoralis minor muscle). Integument of the anterior surface of the inner side of the forearm as low as the wrist. Integument of the posterior surface of the inner side of the forearm to near the wrist. May, occasionally, be wanting (the intercosto-humeral nerve taking its place). Integument of the posterior surface of the lower third of the arm (joining with the intercosto-humeral nerve and the posterior branch of the internal cu- taneous nerve). f Articular (to elbow joint) — several small filaments. i Flexor carpi ulnaris, Muscular. } Inner half oi flexor pro- ( fundus digitorum. \ Integument of front of In the forearm. In hand. Palmar cuta- neous. Dorsal cuta- neous. (^ Articular. Superficial branches. Deep branches. wrist and palm of hand. ' Integument at back of wrist and one and one half fingers on inner side of dorsal surface of hand. -{ To wrist joint. ( Palmaris brevis, J Integument of inner one and one half fingers on palm. Muscles of little finger, Interossei muscles, The two inner lumbricales. Adductor pollicis, Flexor brevis pollicis {in- ner head. The accompanying tables will afford us a better conception of the distribution of the branches of the three main cords of the brachial plexus than a long verbal description ; while they will also enable us, in studying the practical points suggested by the distribution of each branch, to use the eye as well as the intelligence in following the subsequent lectures. It is often impossible for one, not previously familiar with the detail of the nerve distribution of any part, to appreciate all the deductions which may be drawn by an author, without much labor in reviewing the preceding text of the work which he may be endeavoring to master ; and I believe that, in fol- ' Modified from a table in " The Essentials of Anatomy " (Darling and Ranney). New York : G. P. Putnam's Sous, 1880. 384 THE SPIKAL NERVES. lowing these lectures, these tables will greatly assist in such review, as well as in affording you a chart which can be used as a guide to the preliminary study required in your future attempts to master other treatises. BRANCHES OF THE POSTERIOR CORD OF THE BRACHIAL PLEXUS.^ Branches of the POSTE- RIOR CORD of the bra- chial plex- (1) Subscapular NERVES. (2) Circumflex. (3) MuscuLO- spiral. The upper ^ or 1st. The long^ or 2d. The lower^ or 8d. Superior branch. Inferior branch. Muscular branches. Cutaneous branches. Radial nerve. Posterior interosse ous nerve. i :l Subscapular muscle. Latissimus dorsi. Teres major. Deltoid. Integument over the back of the shoulder. Teres minor, Deltoid (posterior portion), Integument over the outer part of the shoulder. Triceps, Anconeus, Brachialis anticus, Supinator longus. Extensor carpi radialis longior. Integument of the inner and posterior portions, and the outer and anterior portions of arm, Intrgum-ent of the outer aspect of the forearm. (Integument of outer side of External J thumb, branch. | Integument of ball of the 1^ thumb. Internal i Integument of 3^ fingers on branch. •< radial side of dorsum of ( hand. All muscles on back f Anconeus, of forearm except ■< Supinator longus, three . . . . ( Ext. carp. rad.ionjr. Filaments to the wrist joint. There are still some points pertaining to the individual branches of the brachial plexus which can not be shown in a tabular arrangement, but which are, nevertheless, important, as they will enable you to better understand the surgical and medical aspects which are constantly brought to the attention of the active practitioner. In order to avoid, as far as possi- ble, any important omissions, and to afford you a more prac- tical insight into the uses to which a knowledge of the nerves can be applied, I will ask you to follow me in a review of the ' Taken, by permission of the publishers, from " The Essentials of Anatomy ling and Ilanney). New York : G. P. Putnam's Sons, 1880. (Dar- THORACIC AND MUSCULO-CUTANEOUS NERVES. 385 nerves of the upper extremity, using the tabulated charts' as a means of reference, should you become confused as to the source of origin of the nerve under discussion, or fail to grasp its subdivisions and their distribution. THE ANTERIOR THORACIC NERVES. These two nerves are termed the external and the internal, since one arises from the outer cord, and the other from the inner cord of the brachial plexus. The external is sometimes also called the superficial, since it crosses in front of the ax- illary artery and vein to reach the under surface of the great pectoral muscle ; ' while the internal is also called the deep, since it passes between the same artery and its accompanying vein, to be distributed to the under surface of both the great and small pectoral muscles. The two nerves are connected with each other by a loop situated on the inner side of the axillary artery. It is probable (following the axiom of Hilton as to the cutaneous distribution of nerves) that the skin over the pectoral region receives filaments from these nerves as well as from the intercostal nerves. As the pectoral muscles are agents in effecting inspiration, when any impediment ex- ists to breathing, as in asthma, etc., these nerves might be classed as respiratory in function, although that is not their most frequent use. THE EXTERNAL CUTANEOUS OR MUSCULO-CUTANEOUS NERVE. This nerve and its branches will be found given in the table of the subdivisions of the outer cord' of the brachial plexus. It passes through the belly of the coraco-brachialis muscle (hence the name " musculo-cutaneous " ), then between the biceps and the brachialis anticus muscles, to a point slightly above the external condyle of the humerus, where it perforates the deep fascia and divides into its cutaneous ^ See pages 382, 383, and 384 of this volume. ^ The anterior fibers of the deltoid muscle arc said to be supplied chiefly by the tho- racic nerves, as revealed by clinical facts. 2 See page 382 of this volume. 386 THE SPINAL NERVES. branches beneath the median cephalic vein. Now, a reference to the table of its distribution will show you that three mus- cles, which move the arm, are supplied with motor power by means of this nerve ; hence we should expect to find that fila- ments would be sent to both the shoulder and elbow joints, which these muscles move, and I am inclined to think that Fig. 139. — Brachial portion of the musat/o-nttancom, median, and ulnar nerves. (Sappey.) 1, musculo-cutaneous nerve ; 2, branch to the coraco-brachialis muscle ; 3, branch to the biceps muscle ; 4, branch to the brachialis anticus ; 5, anastomotic filament which it receives from the median nerve ; 6, division of this nerve where it crosses the apo- neurosis of the arm ; 7, musculo-spiral nerve passing between the brachialis anticus and supinator longus muscles ; 8, external cutaneous branch of the musculo-spiral nerve ; 9, trunk of the internal cutaneous dividing just below its origin, thus giving off an accessory branch ; 10, anterior or ulnar branch of this nerve ; 11, brachial por- tion of the median and ulnar nerves. I small filaments to the former joint do actually exist, although they are not mentioned in the usual text-books upon anatomy. DISTRIBUTION OF MUSGULO-CUTANEOUS NERVE. 387 We would also expect that any injury ' to the trunk of this nerve would be followed by paralysis or atrophy of these three muscles, as well as by a condition of hyperesthesia or anaesthesia in the portions of integument supplied by its ter- minal filaments (the radial side of the forearm and the ball of the thumb) ; provided that the nerve be irritated or only partly destroyed, as shown in the first case, or entirely de- stroyed, in which case the latter condition should ensue. It is a well-recognized surgical fact that an inflamed condi- tion of the elbow joint tends to create flexion of the forearm, by a contracted state of the brachialis anticus and biceps muscles ; and the distribution of the musculo- cutaneous nerve "" to the joint, as well as to these two muscles, enables us now to understand why the irritation of the articular branches of this nerve should manifest itself in a contracted state of the muscles supplied by it. The relation of this nerve to the median-cephalic vein will also explain why venesection at the elbow is liable to be fol- lowed by the so-called "bent arm." This fact, which has been explained by some authors as the result of an injury done to the fascia, is much more intelligently, to my mind, at- tributed by Hilton to an injury done to the filaments of the musculo-cutaneous nerve, resulting in a sympathetic contrac- tion of the flexors of the elbow. An exostosis growing from the humerus, or the existence of a tumor in the region of the course of this nerve, might cause a similar rigidity of the elbow joint, accompanied, moreover, by a pain which would follow the course of the nerve to its terminal filaments. It has been suggested, by the author above quoted,^ to apply anaesthetics over the course of this nerve in order to insure relaxation of the ^ Hilton reports a case where an officer in the navy presented a very marked instance of injury done to this nerve alone. It caused paralysis and atrophy of the three muscles supplied by the musculo-cutaneous nerve ; but a perfect recovery took place in about two years, in spite of the atrophy which at first existed. ^ The ulnar nerve also furnishes filaments to the elbow joint and supplies the flexor muscles of the forearm. This may also tend to explain the surgical fact that flexion follows inflammation of the elbow, ^ Hilton, op. cit. 388 THE SPINAL NERVES. muscles supplied by it when the elbow is thus flexed. Many cases may be cited from different surgical and medical au- thors, to illustrate the diagnostic value of this and other nerves, in determining accurately the seat and character of disease which is producing distress to the patient ; but, as this aid to diagnosis has already been discussed at some length in previous lectures, I will simply mention it as an incentive to anatomical study. The cutaneous distribution of this nerve will be made clear by referring to the diagram which I now show you.' The clinical value of the cutaneous nerves has already been re- ferred to in previous lectures." It will therefore suffice to again mention, in this connection, that hyperaesthesia, local pain, local points of tenderness, and anaesthesia have often a most direct and positive bearing upon diagnosis ; and the axioms given in the first lecture upon the spinal nerves will prove most valuable as guides to the proper appreciation of their significance. It may strike some of you who have thought deeply con- cerning the peculiarities of nerve distribution, that this nerve ought to stop at the elbow, since it has supplied all of its muscles before it reaches that point, and has, therefore, appar- ently performed its function ; and this feeling will possibly be strengthened by the axiom given you in a previous lec- ture," viz., that a nerve is always associated with that portion of the integument which covers the points of insertion of the muscles to which it furnishes motor power. If you will ex- amine closely, however, into the insertion of the biceps mus- cle, you will observe that it is intimately connected with the fascia of the forearm — so intimately that this fascia is, in re- ality, an inherent part of the insertion of that muscle. This, then, confirms not only the truth of the general axiom given by Hilton,* but also explains to the inquiring mind why this nerve should be continued downward to the wrist, since it has to do so in order to cover the skin over one of the most impor- ' See page 396 of this volume. ' See pages 359 and 3G0 of this volurae. * Sec page 359 of this volume. ^ Op. cit. DISTRIBUTION OF MUSCUL0-CUTANE0U8 NERVE. 3S9 tant points of insertion of a muscle wMcli it controls. Other facts in the anatomy of the forearm seem to still more beauti- FiG. 140. — Cutaneous mrves of the anterior surface of the forearm and hand. (Hirsch feld.) 9, epi-trochlear branch from the musculo-spiral nerve anastomosing by a division with the antei'ior branch of the same nerve ; 10, 10, anterior branch of the internal cuta- neous of the arm dividing into several branches, some of which pass in front of and others behind the median basilic vein; 11, 11, musculo-cutaneous nerve crossing the aponeurosis of the arm outside of the tendon of the biceps muscle; 12, 12, di- visions of the external cutaneous branch of the radial distributing themselves to the skin of the posterior portion of the forearm; 13, 18, 13, divisions which the anterior branch of the internal cutaneous furnishes to the forearm ; 14, anastomosis of one of these divisions with a perforating branch of the ulnar nerve; 15, 15, 15, termi- nal divisions of the musculo-cutaneous nerve; 16, anastomosis of one of these divisions with 1*7, the terminal anterior branch of the radial nerve; 18, palmar cutaneous branch of the median; 19, internal branch of distribution to the thumb; 20, external branch of distribution to the same ; 21, external branch of distri- bution to the index finger; 22, trunk of the branches of distribution to the in- ternal side of the index and external aspect of middle fingers ; 23, common trunk of distribution to the internal side of the middle and external side of the ring fingers ; 24, trunk of distribution to the internal side of the ring and external side of the little finger ; 25, branch of distribution to the internal side of the little finger. 27 390 THE SPINAL NERVES. fully confirm this same general law. We see the musculo- sijiral nerve sending a filament to nearly the same region as the musciilo-cutaneous, because it supplies the sujDinator lon- gus, which is situated upon the outer side of the forearm ; while, again, the internal cutaneous nerve (which properly may be considered as a branch of the median, since it arises by a common head) supplies the skin of the inner side of the anterior surface of the forearm, for the evident reason that the muscles supplied by the median are extensively attached to this same fascia. CLINICAL POINTS PERTAINING TO THE MUSCULO-CUTANEOUS NERVE. A paralysis limited to this nerve is an unusual occurrence. It may be produced, however, by any form of injury or of local pressure which alone involves this nerve trunk, and it must be situated in the region of the coraco-brachialis muscle to create impairment of all of its filaments of distribution. Complete paralysis of this nerve causes total paralysis of the biceps and coraco-brachialis muscles, but only a partial loss of power in the brachialis anticus, since that muscle is also furnished with a filament derived from the musculo-spiral nerve. The skin of the outer border of the forearm is also rendered anaesthetic when this nerve is injured. As a result of paralysis of the muscles named, the power to flex the fore- arm upon the arm is greatly impaired, and would be totally lost if the supinator longus and a part of the brachialis anti- cus muscles were not capable of assisting that movement. These latter muscles, being supplied by the musculo-spiral nerve, still retain their power of contraction ; hence the diffi- culty in performing flexion of the forearm is greater when the hand is supinated, as the supinator longus no longer acts to any great extent as a flexor.' The seat of the anaesthesia is a valuable guide to the nerve affected, as the musculo-cuta- ' The supinator muscle is an important aid in flexion of the forearm, when the hand is pi'onafcd : but it is of little value as a flexor after the function of supination has been performed by it. THE MEDIAN NERVE. 391 neons nerve may possibly be involved, without any impair- ment of the other branches of the outer cord of the brachial plexus. Fi7. 141. — Cutaneous nerves of the shoulder and posterior surface of the arm. (Sappey.) 1, 1, terminal ramifications of the supra-acromial branch of the cervical plexus ; 2, cuta- neous branch of the axillary nerve ; 3, another cutaneous branch of the same nerve traversing the posterior border of the deltoid ; 4, terminal divisions of the perforat- ing branch of the second intercostal nerve ; 5, perforating branch of the third in- tercostal nerve ; 6, internal cutaneous branch of the musculo-spiral nerve ; 7, epi- trochlear branch of the internal cutaneous nerve ; 8, posterior division of the ulnar branch of the internal cutaneous ; 9, external cutaneous division of the radial nerve ; 10, 10, internal cutaneous filament of the radial nerve. THE MEDIAN" KERVE. While this nerve arises by two heads, derived, respectively, from the outer and inner cords of the brachial plexus, it has been classed as a branch of the former.' This nerve bears a ^ The reader is referred to the table on page 378 of this volume. 392 THE SPINAL NERVES. Fig. 142. — Cutaneous nerves of the posterior surface of the forearm and hand. (Sappcy.) 7, epi-trochlear branch of the internal cutaneous nerve ; 8, posterior division of the ulnar branch of the internal cutaneous ; 9, external cutaneous division of the radial nerve ; 10, 10, internal cutaneous lilamcnt of the radial nerve; 11, posterior divi.«:ion of the anterior terminal or cutaneous branch of the radial nerve ; 12, first twig rising from this branch (it forms the external dorsal nerve of distribution to the thumbs) ; 13, sec- ond twig of the same division- (it subdivides at the superior part of the first intercostal space — one of these divisions forms the internal dorsal cutaneous nerve of the thumb, the other ramifies in the skin of the dorsal face of the first phalanx of the index finger) ; 14, third branch, which descends into the second interosseous space, where it bifurcates (one of these divisions is lost in the internal half of the integument on the dorsal surface of the first phalanx of the index finger, and the other in the exter nal half of the skin which covers the dorsal surface of the middle finger) ; 15, dorsal branch of the ulnar nerve; 16, external division of this branch anastomosing with one or two filaments of the anterior terminal branch of the radial passing directly into the third interosseous space, where it divides (one of these divisions ramifies in the internal half of the skin which invests the first phalanx of the middle finger, the other supplies the first phalanx of the ring finger); 17, second ramification of the same branch, which also bifurcates under the fourth interosseous space (one of these divisions ramifies in the skin on the dorsal surface of the first phalanx of the ring finger, the other forms the external dorsal nerve of distribution to the little finger) ; 18, internal dorsal nerve of distribution to the little finger. DISTRIBUTION OF THE MEDIAN NERVE. 393 surgical relation to the hracJiial artery^ since it lies, at first, upon the outer side of that vessel, then crosses it, and, finally, reaches its inner side at the bend of the elbow. It enters the forearm between the two heads of the pronator radii teres muscle, passes down the middle line of the anterior surface of the forearm till it reaches the annular ligament of the wrist, then passes underneath the arch formed by that ligament, when it becomes flattened and expanded in front of the flexor tendons in the palm of the hand, and finally terminates in branches to the muscles and integument of the hand and fingers. The table, which has been referred to in previous lectures,' will show, more plainly than a tedious verbal de- scription, the parts supplied by this nerve in the different por- tions of its course. This nerve, in connection with its fellow, the ulnar nerve, furnishes motor power to all the flexor and ipronator muscles of the forearm, and all the muscles of the palm of the hand ; the median supplying all the muscles on the anterior surface of the forearm but one and a half (the flexor carpi ulnaris, and one half of the flexor profundus digi- torum), and four and a half muscles on the radial side of the palm (as shown by the table). Now, as the ulnar nerve sup- plies all the rest of the muscles of the anterior surface of the forearm and hand, these two nerves may be considered as the flexor ViTidi pronator nerves of those regions.'' The cutaneous distribution of the median nerve is of in- terest, since it confirms the axiom ' of nerve distribution to the integument over the muscles. We find that the median sends no cutaneous filaments to the dorsal surface of the thumb, but that it does supply its palmar surface ; the dorsal surface is covered with the extensor tendons, which owe their motor power to the radial n^rve, and the skin is therefore supplied from the same source. The sides of the outer two and a half fingers (those adjoining the thumb) are likewise supplied ' See page 382 of this volume. '^ In speaking of the combined action of the median and ulnar nerves, Hilton says : "These nerves, together, supply all the flexors of the wrist joint, fingers and thumb, all the pronators of the radio-ulnar joints, and all the joints that these muscles move." ^ See page 357 of this volume. 394 THE SPIXAL NERVES. Fig. 144.— Terminal portion of the median and ulnar nerves. (Sappey.) Fig. 143. — Brachial portion of the muscrdo- cutaneous^ median, and ulnar _ nei'ves. (Sappey.) 1, musculo-cutaneous nerve ; 2, branch to the coraco-brachialis muscle ; 3, branch to the biceps muscle ; 4, branch to the brachialis anticus ; 5, anastomotic filament which it receives from the median nerve ; (>, division of this nerve where it crosses the apo- neurosis of the arm ; 7, musculo-spiral nerve passing between the brachialis anticus and supinator longus muscles ; 8, external cutaneous branch of the musculo-spiral nerve ; 9, trunk of the inteVnal cutaneous dividing just below its origin, thus giving off an accessory branch; 10, anterior or ulnar branch of this nerve ; 11, brachial portion of the median and ulnar nerves ; 12, antebrachial portion, pahnar and digital branches of the same nerve; 13, branch to the pronator radii teres; 14, trunk of these anterior muscular branches dividing and passing to the muscles to which they are distributed; 15, branch to the flexor profundus digitorum; 16, branch to the flexor longus poUicis ; 17, anterior interosseous branch ; 18, palmar cutaneous branch dividing just below its origin; 19, muscular branch of the thenar eminence; 20, ex- ternal branch of distribution to the thumb ; 21, internal branch of distribution to the same; 22, external branch of distribution of the index finger; 23, common trunk of the internal branches of distribution to the index finger and external to the middle finger ; 24, internal trunk of distribution to the middle and external branch to the ring finger; 25, branch which the ulnar nerve furnishes to the flexor carpi ulnaris; 26, branches which the same nerve furnishes to the two internal fasciculi of the flexor profundus digitorum; 27, cutaneous and anastomotic filament of the ulnar nerve ; 28, dorsal branch of this nerve ; 20, its superficial palmar branch ; 30, com- mon trunk of the internal branch of distribution to the ring and external branch to CLINICAL POINTS AFFORDED BY MEDIAN NERVE. 395 the little finger ; 31 ; internal branch of distribution to the little finger ; 32, deep palmar branch ; 33, small branch to the hypo-thenar eminence ; 34, branches to the muscles of the fourth interosseous space and the fourth lumbricalis muscle ; 35, branches to the muscles of the third interosseous space and the third lumbricalis muscle ; 36, branches to the adductor pollicis and muscles of the first and second interosseous spaces. with in teg am en tary branches from the median, the balance being supplied by similar branches of the ulnar nerve. The two outer lumbricales muscles are enumerated in the preceding tables, as supplied by the median, and the remain- ing lumbricales and interossei muscles by the ulnar nerve. Now, the method of insertion of the tendons of these muscles (into the extensor tendon of the corresponding finger, on its dorsal surface) causes these muscles to Jlex the proximal phalanx^ and extend the two remaining phalanges ' of each finger. We find, therefore, that the nerve branches, which supply these muscles, send cutaneous filaments to the dor- sal surface of the two terminal phalanges of the finger upon which the individual muscles act, thus apparently confirming the extensor action of the muscles, since the distribution of nerves, derived apparently from a flexor source, comprises a region covered by the extensor tendons of the fingers. CLII^ICAL POIi^TS PERTAIIsriNG TO THE MEDIAN" NERVE. The median nerve is rarely affected with paralysis, to the exclusion of other nerves. If such a condition exists, it may probably be traced to some local injury, such as cuts, frac- tures of the humerus, the use of badly constructed crutches, contusions over the course of the nerve, gunshot wounds, un- skillful venesection, local pressure from tumors, abscess, etc. It may possibly be due to rheumatism, neuritis,' neuromata, and central causes. The muscles of the ball of the thumb, which are supplied by this nerve, are frequently the seat ^ Hunter, Cleland, Duchenne, Erb, and others consider the interossei muscles alone as extensors of the two terminal rows of phalanges. Clinical facts observed in lead paraly- sis and in division of the ulnar nerve seem to point to these muscles rather than to the lumbricales, although Hilton groups the lumbricales and interossei muscles as possessing a common function. '^ This condition may follow any acute disease. It is one of the sequelae of typhoid fever. 396 THE SPINAL NERVES. of a progressive muscular atrophy and its consequent paral- ysis. From what has already been said respecting the distribu- 11 Fig. 145. — A diagram of the regions of cutaneous net've distribution in the anlci'ior sur- face of the upper extremity and trunk. (Modified from Flower.) 1, region supplied by the supra-clavieular nerve (branch of the cervical plexus) ; 2, re- gion supplied by the circumflex nerve ; 3, region supplied by the intercosto-hunieral nerve ; 4, region supplied by the intercostal nerve (lateral branch) ; 5, region sup- plied by the lesser internal cutaneous nerve (nerve of Wrisberg') ; 6, region supplied by the musculo-spiral nerve (external cutaneous branch) ; 7, region supplied by the internal cutaneous nerve ; 8, region supplied by the musculo-cutaneous nei've ; 9, region supplied by the median nerve ; 10, region supplied by the ulnar neive ; 11, region supplied by the intercostal nerve (anterior branch). tion of this nerve, we are prepared to understand why the common flexors of the fin^^ers and those of the wrist should PARALYSIS OF THE MEDIAN NERVE. 397 show a loss of power, in case the median be injured, and the muscles of the thumb give evidence of the diseased condition. You will find, in such cases, that the second phalanges of all the fingers and the third phalanges of the index and middle ' fingers can not be flexed, and that the thumb can not be flexed or brought into contact with the little finger. On the other hand, flexion of the first phalanx, with extension of the other two, can be performed in all the fingers by the aid of the interossei which are supplied by the ulnar nerve. The position of the thumb is peculiar; it is extended and ad- ducted and thus closely applied to the index finger, as in the hand of the ape. The hand, when flexion at the wrist is attempted, is strongly adducted by the action of the flexor carpi ulnaris, as the antagonistic muscle of the radial side is paralyzed. The act of pronation of the hand is seriously im- paired. The inner three fingers can be brought into a par- tially flexed condition, since the flexor profundus digitorum muscle is partly supplied by the ulnar nerve. These com- bined effects give to the hand and fingers, and especially to the thumb, a position so peculiar that paralysis of the median could hardly be mistaken by an anatomist for any other de- formity. When the paralyzed muscles begin to show the results of atrophy, the deformity in the forearm and in the ball of the thumb will further assist in the diagnosis of this affection. The anastomosis which exists between the cutaneous nerves of the forearm will possibly tend to explain the fact that com- plete destruction of the median, ulnar, or radial nerves may exist without any marked loss of sensibility in the regions supplied by the affected nerve. Should any such evidences of disordered sensibility be present, however, it will be con- fined to the region supplied by the nerve which is the seat of disease, or whose conducting power has been impaired from any cause. If the median, ulnar, or radial nerves be injured below the wrist, the absence of anastomosis tends to make the ' The flexor sublimis digitorum being completely paralyzed, and the flexor profundus digitorum being partially deprived of its motor power. 398 THE SPINAL XEEVES. symptom of anaesthesia a constant and important guide to the nerve affected. In severe paralysis of the median nerve, the first three fingers ' not infrequently show trophic disturbances in the skin and nails, such as glossy fingers, ulceration, pemphigus vesicles, abnormal growth of hair, etc. The relation of the median nerve to the brachial artery gives to it a surgical importance. It will be observed that the nerve lies, at first, to the outer side of that vessel ; later on, it crosses it, and finally passes to the inner side of the artery in the region of the elbow. THE IXTERNAL CUTANEOUS AND LESSER INTERXAL CUTANEOUS NERVES. These two nerves arise from the inner cord of the brachial plexus, in common with the inner head of the median and the ulnar nerves. The internal cutaneous nerve accompanies the brachial artery, lying upon its inner side and in front of the lesser in- ternal cutaneous nerve, till the basilic vein pierces the deep fascia, when the nerve accompanies the vein and soon divides into an anterior and posterior branch, whose distribution will be. found given in preceding tables. It assists the coraco- humeral nerve in supplying the integument over the biceps muscle, and sends filaments to the skin of the forearm as low down as the wrist." The lesser internal cutaneous nerve, called also the nerve of Wrisberg,' has the same general origin as the preceding nerve, except that it arises slightly below it. Like the former nerve, it accompanies the brachial artery, lying upon its inner side and behind the nerve just described, and, after its escape from the fascia, it supplies the skin of the lower third of the arm,* becoming joined to the posterior branch of the internal ^ Those adjoining the thumb. Sec figure on page 396 of this volume. ' See cut on page 396 of this voUmie. 3 For the region of cutaneous distribution to this nerve, the reader is referred to the diagrammatic cuts on pages 389 and 396 of this volume. * See Fig. 145 of this volume. THE ULNAR NERVE. 399 Fig. 146. — Cataneoim nerves of the shoul- Fig. 147. — Cutaneous nerves of the anfe- der and anterior surface of the arm. rior surface of the forearm and hand. (Hirschfeld.) (Hirschfeld.) 1,1, divisions of the supra-acromial branch of the cervical plexus ; 2, 2, 2, terminal rami- fications of the cutaneous division of the circumflex nerve ; 3, division of the inter- nal cutaneous nerve of the arm ; 4, small filament from the perforating branch of the second intercostal nerve; 5, external cutaneous branch from the musculo-spiral- nerve ; 6, internal cutaneous branch crossing the aponeurosis of the arm ; 7, epi- trochlear branch of this nerve, anastomosing by a division with 8. the ulnar nerve, and 9, 9, with the anterior branch of the same nerve ; 10, 10, anterior branch of the internal cutaneous of the arm, dividing into several branches, some of which pass in front of and others behind the median-basilic vein ; 11, 11, musculo-cutaneous nerve crossing the aponeurosis of the arm outside of the tendon of the biceps muscle ; 12, 12, divisions of the external cutaneous branch of the radial, distributing themselves to the skin of the posterior portion of the forearm ; 13, 13, 13, divisions which the anterior branch of the internal cutaneous furnishes to the forearm ; 14, anastomosis of one of these divisions with a perforating branch of the ulnar nerve; 15, 15, 15, terminal divisions of the musculo-cutaneous nerve; 16, anastomosis of one of these divisions with lY, the terminal anterior branch of the radial nerve ; 18, palmar cuta- neous branch of the median ; 19, internal branch of distribution to the thumb ; 20, external branch of distribution to the same; 21, external branch of distribution to the index finger ; 22, trunk of the branches of distribution to the internal side of the index and external aspect of middle fingers ; 23, common trunk of distribution to the internal side of the middle and external side of the ring fingers ; 24, trunk of distri- bution to the internal side of the ring and external side of the little finger ; 25, branch of distribution to the internal side of the little finger. 400 THE SPINAL NERVES. cutaneous nerve or to the intercosto-humeral nerve. The size of this nerve varies, as it is often supplanted by the intercos- to-humeral ' nerve, which is then of extremely large size„ In this case the nerve of Wrisberg may be entirely wanting, and the intercosto-humeral nerve act independently of any communication with the brachial plexus. THE ULNAR NERVE. This nerve arises from the inner cord of the brachial plex- us, in common with the internal cutaneous and the nerve of Wrisberg, as well as with the inner head of the median nerve. It bears a surgical relation with the third portion of the ax- illary artery and the upper part of the brachial artery, since it lies internally to and in close proximity with both ; but it gradually separates from the brachial artery as it passes down the arm. It perforates the deep fascia of the arm in company with the inferior profunda branch of the brachial artery, and descends in a groove between the olecranon process of the ulna and the inner condyle of the humerus, until it enters the forearm by passing between the two heads of the flexor carpi ulnaris muscle. In the forearm, this nerve bears a relation with the ulnar artery, especially in the middle and lower thirds of that region ; the artery lying upon the outer side of the nerve. At the wrist, this nerve winds around the outer side of the pisiform bone, crosses the annular ligament, and divides into its two terminal branches. The tabulated ar- rangement of the branches of distribution of the ulnar nerve ' will show the muscles supplied by it, both in the forearm and hand. It is important to remember that this nerve gives fila- ments to both the elbow and wrist joints, and that its cutane- ous branches are confined to the fingers and palm of the hand. By a glance at the diagrammatic representation of the regions of the integument of the upper extremity, supplied by individual nerves (see Figs. 145 and 153), you will per- ceive that the ulnar nerve supplies the dorsal and palmar ' A branch of the second intercostal nerve. ' See page 383 of this vohime. DISTRIBUTION OF THE ULNAR NERVE. 401 Fig. 148. — Brachial portion of the musculo- FiG. 149.— Terminal portion of the median cuta)icous, median, and ulnar nerves. and ulnar nerves. (Sappey.) (Sappey.) 1, musculo-cutaneous nerve ; 2, branch to the eoraco-braehialis muscle ; 3, branch to the biceps muscle ; 4, branch to the brachialis anticus ; 5, anastomotic filament which it receives from the median nerve ; 0, division of this nerve where it crosses the apo- neurosis of the arm ; 7, musculo-spiral nerve passing between the brachialis anticus and supinator longus muscles ; 8, external cutaneous branch of the musculo-spiral nerve ; 9, trunk of the internal cutaneous dividing just below its origin, thus giving off an accessory branch; 10, anterior or ulnar branch of this nerve ; 11, brachial portion of the median and ulnar nerves ; 12, antebrachial portion, palmar and digital branches of the same nerve; 13, branch to the pronator radii teres; 14, trunk of these anterior muscular branches dividing and passing to the muscles to which they are distributed; 15, branch to the flexor profundus digitoi-um; 16, branch to the flexor longus pollicls ; 17, anterior interosseous branch ; 18, palmar cutaneous bi'anch dividing just below its origin; 19, muscular branch of the thenar eminence; 20, ex- ternal branch of distribution to the thumb ; 21, internal branch of distribution to the same; 22, external branch of distribution of the index finger; 23, common trunk of the internal branches of distribution to the index finger and external to the middle finger; 24, internal trunk of distribution to the middle and external branch to the ring finger ; 25, branch which the ulnar nerve furnishes to the flexor carpi ulnaris ; 26, branches which the same nerve furnishes to the two internal fasciculi of the flexor profundus digitorum ; 27, cutaneous and anastomotic filament of the ulnar nerve ; 28, dor«;al branch of this nerve ; 29, its superficial palmar branch ; 30, com- mon trunk of the internal branch of distribution to the ring and external branch to 402 THE SPIXAL XERYES. the little finger; 31; internal branch of distribution to the little finger; 32, deep palmar branch ; 33, small branch to the hypo-thenar eminence ; 34, branches to the muscles of the fourth interosseous space and the fourth luiiibricalis muscle ; 35, branches to the muscles of the third interosseous space and the third lumbricalis muscle ; 36, branches to the adductor poUicis and muscles of the first and second interosseous spaces. surfaces of the inner one and a half fingers^ thus leaving three and a half fingers upon the palm for the median nerve, and three and a half fingers on the back of the hand for the radial nerve to supply. Thus the integument of the palm is as equally divided between these three nerves as could well be, as the ulnar has a total of three fingers (one and a half on both the palm and back of hand), and the other two nerves three and a half fingers each. CLINICAL POINTS OF INTEREST PERTAINING TO THE ULNAR NERVE. The superficial situation of this nerve in the arm, near the elbow and at the wrist, would seem to suggest that paralysis of this nerve would be a matter of common occurrence, as it is apparently exposed to injury. It is, nevertheless, infre- quently affected with traumatic paralysis. The causes which reported cases show to have produced this condition include about the same list of accidents as mentioned in connection with paralysis of the median nerve ; but sleeping upon the ann when placed beneath the head, the use of poorly constructed crutches, fractures and dislocations at the shoulder, tumors, contusions, wounds of all kinds, neuritis,' and neuromata are among the most common. Eesting upon the elbow has been reported by Duchenne as a cause of this type of paralysis in a certain class of workmen ; and the so-called '' injury to the funny bone," which consists of a contusion over the seat of the ulnar nerve at the elbow, seems to justify the conclusion that this might easily be the seat of paralysis from long-con- tinued or constant pressure. It is a rule among surgeons, when operating about the elbow joint,' to guard against injury to the ulnar nerve, espe- ' Rosenthal states that this condition is most frequent after typhoid fever and acute diseases. ' This is especially important in excision of this joint, as the nerve is apt to be injured in raising the periosteum from the bone. CLINICAL POINTS AFFORDED BY ULNAR NERVE. 403 cially when the steps of the operation bring the knife in proximity to the inner condyle of the humerus. As has been mentioned in connection with the median nerve, the ulnar, as well as the median nerve, may be considered as a pronator and flexor nerve of the wrist and a flexor nerve of the fingers, since the distribution of the two is confined exclusively to the anterior surface of the forearm and the palmar surface of the hand. The table of the branches of the ulnar nerve ' will help us to readily appreciate the peculiari- ties of ulnar paralysis from a theoretical standpoint, and to properly interpret the phenomena when met in actual expe- rience. We can see, by reference to the table, that the flexor carpi ulnaris and the greater part of the flexor profundus digito- rum muscles would be paralyzed, and that the muscles of the hypo thenar eminence, as well as the interossei muscles of the hand, the two inner lumbricales, a part of the flexor brevis pollicis, and the adductor poUicis would be similarly affected. Now, the clinical evidences of this form of paralysis are in perfect accord with these facts. We find that the ad- duction of the hand is no longer performed in a perfect man- ner, since the flexor carpi ulnaris can no longer act in unison with the extensor carpi ulnaris ; that flexion of the hand is performed imperfectly and by means of the flexor of the ra- dial side of the forearm only, since that muscle is supplied by the median nerve : that the ability to move the little fin- ger is almost entirely abolished ; that complete flexion of the inner three fingers is rendered diflicult and sometimes impos- sible ; that the fingers can not be separated from each other, or compressed into a close lateral juxtaposition, owing to paralysis of the interossei muscles ; and that both flexion of the flrst phalanx and extension of the two terminal pha- langes of all the fingers are rendered impossible, for the same reason. When the ulnar nerve is paralyzed above tJie icrist^ so that the interossei and lumbricales are alone paralyzed, the hand ^ See page 383 of this volume. 404 THE SPmAL NERVES. assumes a diagnostic attitude, the so-called ''claw-hand," in which the extensor communis digitorum muscle extends the first phalanges of all of the fingers, while the other two rows of phalanges are flexed by the common flexor muscles of the fingers (the interossei and lumbricales being no longer able to flex the first row of phalanges or to extend the two other rows). This same condition of the hand may, however, be produced by a condition of progressive muscular atrophy of these muscles. It must be remembered that this condition, if dependent upon ulnar paralysis alone, is more marked in the two inner fingers than in the three outer, since the lumbricales are sup- plied in part by the median nerve ; and this clinical fact seems to stamp the action of the lumbricales as similar to that of the interossei. Finally, the effects of ulnar paralysis may be manifested in the movements of the thumb, since it supj^lies two muscles which control it. This will be most apparent when you instruct the patient to press the thumb forcibly against the metacarpal bone of the index finger, or to adduct the thumb, since both of these motions will be rendered diffi- cult or impossible. These disturbances of motility create serious disturbances in those common functions in which the hand is of the most service. Writing, drawing, the playing of musical instru- ments, etc., are rendered difficult. The muscles which are supplied by the median and radial nerves are still able, how- ever, to direct the hand and fingers in many acts which con- tribute to the comfort of the patient. In those cases where the muscles of the thenar eminence (supplied chiefiy by the median nerve) are simultaneously affected, the use of the hand is almost entirely abolished. THE SUBSCAPULAR NERVES. These three nerves are given off by the posterior cord of the brachial plexus. They are called the upper, long, and lower subscapular nerves by some authors, while the numerical prefixes of first, second, and third are applied to them by THE SUBSCAPULAR NERVES. 405 others. As will be seen by the table of tlie branches of the posterior cord of the brachial plexus, ' the first or upper nerve supplies the subscapular muscle, the second or long nerve supplies the latissimus dorsi, and the third or lower nerve supplies the teres major, whose point of insertion is similar to that of the preceding muscle, since the tendons of the two often merge into each other. ]^ow, these three muscles are agents in creating certain movements at the shoulder joint ; hence it is to be presumed that each subscapular nerve sends a filament to that articula- tion. I am aware that the text-books usually give the credit of nerve supply to this joint to other sources, since the fila- ments of the supra-scapular and circumflex nerves can be traced easily to this articulation on account of their large size, but I am not inclined to believe that an axiom ^ of nerve sup- ply, so fully sustained in other regions, will not fail to be supported by careful dissections of this part. The muscles supplied by the subscapular nerves are as important agents in the movements of the arm at the shoulder as those supplied from the trunks of the circumflex and the supra-scapular nerves ; and, if it be true that a joint, when exhausted or inflamed, can control the muscles which move it by means of a common nerve supply, the subscapular nerves must cer- tainly be enumerated as one of the sources of supply to the shoulder joint. CLINICAL POINTS PEETAINING TO THE SUBSCAPULAR NERVES. These nerves are seldom the seat of a localized neuralgia, or of paralysis, except in connection with some other nerves of the upper extremity. The situation at which they are given off from the brachial plexus (being branches of the posterior cord and imbedded in the axillary space) is a safe- guard against all common forms of external violence, while few tumors would create pressure upon these trunks without affecting other nerves at the same time, and possibly to an equal or greater degree. J See page 381 of tliis volume. 2 gee page 359 of this volume. 28 406 THE SPINAL NERVES. Should the subscapular nerves happen to become impaired, the paralysis would be shown in those movements of the arm which are performed chiefly by the three muscles supplied by them. The latissimus dorsi could no longer bring the hand into the position assumed when scratching the anal region (in which movement it is prominently concerned), while the move- ment of internal rotation at the shoulder joint would be im- paired, on account of the paralysis of the subscapularis and the teres major, as well as that of the muscle previously mentioned. Should these nerves be the seat of degeneration, as in the case of progressive muscular atrophy, an alteration in the size of the latissimus dorsi and teres major muscles would be detected, and the other symptoms characteristic of this condition might be discovered, to a greater or less degree, depending upon the extent of the muscular changes. THE CIRCUMFLEX NERVE. This nerve arises from the posterior cord of the brachial plexus, usually in common with the musculo-spiral nerve, but sometimes by an independent communication with the posterior cord. It passes downward and outward behind the axillary artery and upon the subscapularis muscle, then backward (in company Avith the circumflex vessels) through a quadrilateral space bounded by the humerus, the teres ma- jor and minor muscles, and the long head of the triceps,* when it divides into its superior and inferior branch. It gives off a distinct branch to the shoulder joint, before its two terminal branches are formed, in the vicinity of the quadri- lateral space, whose boundaries have been given. The superior branch of the circumflex nerve is the larger of the two teiminal filaments. It winds around the neck of the humerus, and supplies the deltoid muscle and the integu- ment over the lower portion of the shoulder. The inferior branch is small in comparison with the su- perior, and is distributed to the teres minor muscle and the ' This space can be found depicted in all the standard text-books upon anatomy. THE CIRCUMFLEX NERVE. W. integument over the back part of the shoulder. The twig, given off to supply the teres minor muscle, is sometimes fur- nished with a ganglionic enlargement. • CLINICAL POINTS PERTAINING TO THE CIRCUMFLEX NERVE. From what has been said regarding the distribution of this nerve, it will be readily understood that the deltoid and teres minor muscles, as well as the integument of the shoulder and Fig. 150. — Circumflex and subscapular nerves. (Sappey.) 1, tentiinal extremity of the supra-scapular nerve ; 2, branch which this nerve furnishes to the supra-spinatus muscle ; 3, ramifications by which it terminates in that muscle ; 4, circumflex nerve embracing the surgical neck of. the humerus ; 5, filament which this nerve sends to the teres minor muscle ; 6, cutaneous nerve to the shoulder ; V, branches of the circumflex nerve given off to the deltoid muscle. upper arm, will be affected by any impairment of the circum- flex nerve. A fact previously mentioned, however, should not be lost sight of, viz., that the deltoid muscle, in its an- terior portion, is supplied by the anterior thoracic nerves ; hence the impairment of the circumflex may not utterly para- lyze it. The intimate relations which this nerve bears to the shoulder joint and the course which it takes around the neck of the humerus render it particularly liable to injury from contusions, concussions, blows, or falls upon the shoul- 408 THE SPINAL NERVES. der; while dislocations of the humerus from the scapula, especially in a backward direction, are frequently followed by deltoid paralysis. If the shoulder joint become the seat of rheumatic, or any other type of chronic inflammation, the nerve may be involved in a neuritic process, and thus cau.^^ a paralysis of the deltoid or teres minor ; while the same re- sults may also follow "catching cold," a neuritis being prob- ably established. Finally, this type of paralysis may follow injury to the brachial plexus, all the forms of central lesions, lead poisoning, and progressive muscular atrophy. As paralysis of the teres minor muscle can not be easily detected, provided the infra-spinatus muscle remains unim- paired, the symptoms of circumflex paralysis are mostly con- fined to the inability to perform the various movements into which the deltoid muscle prominently enters. The arm can not be raised from contact with the wall of the thorax, by any attempt on the part of the patient, nor can it be brought for- ward and raised. When an attempt is made by the patient to raise the arm, the deltoid fibers do not contract, but lie flabby and loose, which distinguishes it from an anchylosed condition of the shoulder, without the necessity of communi- cated motion being resorted to in order to make the diagno- sis. The deltoid region atrophies, and the shoulder joint becomes relaxed. A deep groove can often be detected through the atrophied muscle between the head of the hu- merus and the articular surface of the scapula. THE MUSCULO-SPIRAL NERVE. This is the largest branch of the brachial plexus. It arises from the posterior cord, usually in company with the circum- flex nerve, and lies behind the third portion of the axillary artery, at its point of escape from the brachial plexus. It subsequently passes behind the upper part of the brachial artery, crosses the tendons of the teres major and latissimus dorsi muscles, accompanies the superior profunda artery in a spiral groove upon the humerus, and, by passing between the supinator longus and the brachialis anticus muscles, it readies I THE MUSCULO-SPIRAL NERVE. 409 fii fl2 151. — Musculo-spiral nerve. Fig. 152. — Terminal branches of the (Sappey.) musculo-spiral nerve. (Sappey.) 151. — 1, circumflex nerve ; 2. filament to the teres minor muscle ; 3, cutaneous branch of the circumflex ; 4, trunk of the musculo-spiral ; 5, portion of this nerve which cor- responds to the spinal groove of the humerus ; 6, this same nerve passing between the brachialis anticus and supinator longus muscles ; 7, branch which the musculo- spiral furnishes to the long head of the triceps muscle ; 8, 8, branch to the internal portion of this muscle ; 9, branch to the external portion of this muscle; 10, termi- nal branch of this same nerve distributed to the anconeus muscle; 11, another branch of the same nerve supplying also the external portion of the triceps muscle ; 12, external cutaneous branch of the musculo-spiral. 152. — 1, trunk of the musculo-spiral nerve ; 2, branch to the supinator longus muscle ; 3, branch to the extensor carpi radialis longior; 4, branch to the extensor carpi radialis brevior ; 5, bifurcation of this trunk ; 6, its posterior or muscular branch ; 7, the same branch crossing the supinator brevis, to which it gives off several small branches ; 8, its terminal divisions ; 9, anterior or cutaneous branch of this nerve ; 10, terminal divisions of this branch; 11, musculo-cutaneous nerve ; 12, 12, 12, its terminal divisions ; 13, one of these branches which descends as far as the wrist, and then anastomoses with the cutaneous branch of the radial. 410 THE SPINAL NERVES. the external condyle of the humerus, where it divides into two terminal branches, viz., the radial and the posterior in- terosseous nerves. The table of the branches given off from the posterior cord of the brachial plexus,' and the filaments of distribution of each, will help you in following the chief points of interest associated with this nerve. It will be perceived that the main trunk of the nerve supplies five muscles, while the posterior interosseous branch supplies all the remaining muscles upon the posterior surface of the forearm. This nerve is, therefore, essentially an extensor nerve, although the brachialis anticus and supinator longus muscles assist in flexion of the forearm. When we come to the consideration of the effects of paraly- sis of this nerve, the special symptoms will help still further to impress upon you the distribution of its branches to mus- cles as well as to the integument ; and the points of interest, which depend upon the peculiar course of the main trunk of the nerve, will be made prominent, as an explanation of the frequent occurrence of this special type of paralysis in cer- tain occupations. The radial branch is exclusively distributed to the integu- ment, as is shown in the table," and the special distribution of the branches given off by this nerve to the integument of the hand has been already discussed at some length in a previous lecture.' The musculo-spiral nerve gives an articular filament to the wrist joint, by means of its posterior interosseous branch ; and, probably, some filaments also to the elbow joint, if we accept the general law of nerve distribution given by Hilton, so often quoted in the preceding lectures of this course. We are now prepared to examine, with advantage, the dia- grammatic plates,* in which the regions supplied by the dif- ferent nerves of the upper extremity are exhibited more clearly than a verbal description could alone afford. They ' Sec page 384 of this volume. ' See page 384 of this volume. 3 Seepage 402 of this volume. ** See cuts on pages 396 and 411 of this volume. DISTRIBUTION OF MUSCULO-SPIRAL NERVE. 411 will prove of great assistance in studying the tables' in which the branches of the individual nerves are classified. Fig. 153. — A diagram of the regions of cutaneous nerve distribution on the posterior sur- face of the upper extretnity and trunk. 18, region supplied by the second dorsal nerve ; 19, region supplied by the supra-scapular nerve; 20, region supplied by the circumfcx nerve ; 21, region supplied by the iniei'- costo-lvumeral nerve ; 22, region supplied by the external cutaneous nerve ; 23, region supplied by the internal cutaneous branch of the musculo-spiral nerve ; 24, region supplied by the " nerve of Wrisberg ; " 25, region supplied by the lateral branches of the intercostal nerves ; 26, region supplied by the internal cutaneous nerve ; 27, re- gion supplied by the musculo-cutaneous nerve ; 28, region supplied by the iliac branch of the ilio-inguinal nerve ; 29, region supplied by the radial nerve ; 30, region sup- plied by the ulnar nerve. This diagram limits the distribution of each nerve with more positiveness than can be well verified, since the cuta- ' See tables on pages 383, 384, and 385 of this volume. 412 THE SPINAL NERVES. neous filaments of two nerves may supply the borders of any of these regions, as the nerves tend to overlap each other. It is not well, therefore, to rely positively upon the border limits of any region in your endeavors to detect anaesthesia, should you suspect a paralytic condition of any sj^ecial nerve, and seek this means of confirming your diagnosis. The rule of Hilton would naturally cause us to expect that the muscles supplied by any special nerve would act as a guide in determining the source of the cutaneous nerve supply over the points of attachments of those muscles ; and we are not disappointed when we examine closely the area of cuta- neous distribution of the musculo-spiral nerve. This nerve supplies the supinators of the hand, the extensor muscles of the elbow Joint and of the wrist joint, and the extensor mus- cles of the fingers and the thumb ; hence we find the skin over these groups of muscles supplied, to a great extent, by the same nerve which affords motor power to the muscles un- derneath. This fact will thus help you to remember the area of distribution of any nerve to the skin by a process of rea- soning based upon the muscles which are supplied by the same nerve, and the numerous examples, already quoted in confir- mation of this general law, prove that the deduction drawn from it is, in all cases, approximately accurate. CLINICAL POINTS PERTAINING TO THE MUSCULO-SPIRAL NERVE. The musculo-spiral nerve is more frequently affected with paralysis than any of the nerves of the upper extremity. It is particularly liable to both peripheral and central causes of Ijaralysis ; thus, in cerebral hemiplegia, the muscles supplied by this nerve are, perhaps, more commonly affected than those supplied by any other nerve, while paralysis of these muscles is common as the result of chilling of the uj)per extremity, traumatism, and lead poisoning. The anatomical situation of the musculo-spiral nerve and the peculiarity of its course around the humerus probably ex- plain the frequent occurrence of paralysis, since it may be easily compressed by sleeping upon the arm. It is common CLINICAL POINTS AFFORDED BY MUSCULO-SPIRAL NERVE. 413 to meet with this type of paralysis in patients who have nsed their arm as a pillow, or in drunkards who have slept in some constrained position npon benches, steps, etc. Persons who have fallen exhausted and have rested upon the arm, and sol- diers who have slept upon the damp ground, often arise with this form of paralysis. It is stated by Brenner ' that the coach- men of Kussia, who are in the habit of sleeping upon the box with the reins wound around the upper arm, are victims to this condition ; and Bachon ' reports the same result as com- mon among the water-carriers of Rennes, since they pass their arm through the handle of the heavy water-pails to more se- curely compress them against the chest. The habit of the Russians of tightly bandaging the arms of infants to the body, and allowing them to sleep upon one side for long intervals, seems to promote the frequent occurrence of this trouble. Among the other forms of traumatism which conduce toward this form of paralysis may be mentioned the use of poorly padded crutches, the kicks of animals, cuts, stab wounds, fractures of the humerus, dislocation of the humerus at the shoulder joint, and the development of an excessive amount of callus after a fracture. Rheumatic affections and a neuritis of the musculo-spiral nerve are reported as causes by Bernhardt and others ; and cases of hysterical origin have been rarely but positively au- thenticated. Finally, lead poisoning must be mentioned as one of the most common causes of paralysis of the muscles supplied by the musculo-spiral nerve. The existence of this form of poi- soning will have generally been indicated, previous to the ap- pearance of paralysis, by colic, jaundice, and arthralgia, as the muscles are seldom affected until the latter stages. The extensor communis digitorum muscle is usually affected first, and the paralysis gradually extends to the other muscles sup- plied by the musculo-spiral nerve. The muscles of the arm are much less frequently affected than those of the hand and forearm ; but, in severe cases, the muscles of the upper arm, ^ As quoted by Erb. ^ x% quoted by Erb. 414 THE SPINAL NERVES. shoulder, and even those of the lower extremity, may become involved. It is difficult as yet to explain the apparent predisposition of lead poisoning to affect the muscles of the musculo-spiral region in preference to the flexor muscles. Gombault, Bern- hardt, Westphal, Barwinkel, Hitzig, and Lancereaux have given special attention to the subject, and arrived at no com- mon ground upon which they can all agree. The condi- tion has been explained as the result of a venous stasis (Hit- zig), and as the result of arterial ischfemia (Barwinkel) ; both of whom regard these conditions as favoring the deposition of lead in the muscles of the extensor region of the fore- arm. Peripheral nerve degeneration has been claimed as the explanation of the paralytic symptoms by Gombault, Westphal, and Lancereaux, and in this view the investiga- tions of Neuman, Erb, and Eichhorst coincide. Whether a spinal origin will be yet determined which will explain the muscular changes and the loss of power, is yet to be decided by further pathological research. The symptoms which characterize this type of paralysis have such a distinctive form as to be easily recognizable by the physician at the very first glance. A reference to the table which shows the distribution of the musculo-spiral nerve to muscles' will help to explain them. We see that this nerve sends filaments to the triceps and brachialis anticus muscles in the arm, and to all the extensor muscles of the forearm. In accordance with this distribution, the hand is kept in a state of flexion when this nerve is paralyzed, and can not be raised or extended ; the thumb is flexed and ad- ducted ; and the fingers are flexed and cover the thumb. When the patient attempts to extend the fingers, the interos- sei and lumbricales muscles alone can be made to act, and these muscles, as has been mentioned before, can only extend the two terminal phalanges while they flex the basal phalanx.' ' See page 384 of this volume. 5 The explanation of this fact lies in the insertion of the tendons of these muscles into the tendons of the common extensor of the fingers. MUSGULO-SPIRAL PARALYSIS. 415 The thumb and the index finger can not be extended or abducted ; the patient can not supinate the hand when the forearm is extended (this position being assumed in or- der to exclude the action of the biceps muscle), nor can the forearm be half bent and the hand half supinated by the supinator longus muscle ; and, finally, when the patient is instructed to flex the forearm, when placed in a position of half flexion and semi-prostration, the supinator longus muscle lies flaccid, and does not become tense and hard as in health. The loss of power in the triceps muscle ren- ders it impossible for the patient to extend the forearm M. external head of triceps Musculo-spiral nerre ^^ -I M. brachialls anticus — ^"^ * M. supinator lonprus -. M. extensor carpi rad. longior M. extensor carpi rad. brevior . Fig. 154. — The motor points on the outer aspect of the arm. upon the arm when the arm is first raised above the head ; nor can the forearm be extended with the same degree of force as the healthy side in any position of the arm. When the hand is laid upon the table, the patient is un- able to raise the hand from contact with it, but the lateral movements of the fingers can be performed as in health, 416 THE SPINAL NERVES. since these movements are controlled by the interossei mus- cles. The action of the flexor muscles of the wrist seems feeble, since the antagonistic action of the extensors does not afford a fixed point of action ; but, if the wrist be forcibly extended and fixed, it will be seen that the wrist flexors are not paralyzed. This form of paralysis interferes with almost all of the nu- merous employments of daily life, since the functions of the hand are most seriously impaired. The patient can not well hold or grasp anything, on account of the inability to perform 7 8 -_ :^ 12 8 4 5 6 Fig. 155. — The motor points on the inner side of the arm. 1, m. internal head of triceps ; 2, musculo-cutaneous nerve ; 3, median nerve ; 4, m. coraco-brachialis ; 5, ulnar nerve ; 6, branch of median nerve for pronator radii teres ; 7, musculo-cutaneous nerve ; 8, m. biceps flexor cubiti. the extension of the thumb or fingers ; and the impairment of the supinators still further adds to the uselessness of the hand. The regions of the integument supplied by the mus- culo-spiral nerve exhibit more or less anaesthesia, although the extent of this symptom, like that of the muscular pa- ralysis, is modified by the height of the lesion, which affects the nerve as well as by its character. In some cases, exten- sive motor paralysis may be present without any marked MUSCULO-SPIRAL PARALYSIS. 417 disturbance of sensibility ; tliis can only be explained by the presence of anastomosis between the ciitaneous nerves Fig. 156. — Tlie motor points on the extensor {posterior) aspect of the forearm. 1, m. supinator longus ; 2, m. extensor carpi rad. longior ; 3, m. extensor carpi rad. bre- vier; 4, 5, m. extensor communis digitorum; 6, m. extensor ossis. met. pol. ; 7, m. extensor primi. internod. pol. ; 8, m. first dorsal interosseous ; 9, m. second dorsal interosseous; 10, m. third dorsal interosseous; 11, m. extensor carpi ulnaris; 12, m. extensor rain, digiti; 13, m. extensor secund. internod. pol.; 14, m. abduct, min. digiti; 15, m. fourth dorsal interosseous. of different origins, as was demonstrated by Tripier and Ar- loing' upon dogs. In the diagnosis of this type of paralysis, it is often diffi- cult to determine the exact nature and seat of the exciting As quoted by Erb. 418 THE SPINAL NERVES. cause. The most common causes are injury, pressure, and lead poisoning ; but the existence of exciting neuritis, some Fig. 157. — Tlie motor points on the Jlexor {anterim') aspect of tlie forearm. 1, median nerve and branch to m. pronator radii teres ; 2, m. palmaris longus ; 3, m, flexor carpi ulnaris : 4, m. flexor sublim. digit. ; 5, ulnar nerve ; 6, m. flex, sublim. dig. ; 7, volar branch of the ulnar nerve ; 8, m. palmaris brevis ; 9, m. abductor min. digit. ; 10, m. flexor-min. digit. ; 11, m. opponens min, digit. ; 12, 13, m. lumbricales ; 14, m. flexor carpi radialis ;"l6, m. flexor profund. digitorum ; 16, m. flexor sublim. di'rilorum; 17, m. flex, longus pollicis ; 18, median nerve; 19, m. opponens pollicis; 20, m. abductor pollicis; 21, m. flexor brevis pollicis; 22, m. adductor pollicis; 23, m. lirst lumbricalis. cerebral disease, or an hysterical cause, must be excluded or determined by the concomitant symptoms. When the paral- THE DORSAL NERVES. 419 ysis is due to local compression, the triceps muscle is not usu- ally affected, and the same statement applies to the rheumatic form, while in both of these types the disturbance of sensi- bility is most frequently confined to the hand alone. In lead paralysis, the supinator brevis muscle remains unaffected until late in the disease, and the supinator longus muscle is rarely involved, even in severe forms of poisoning. While this can not be taken as an absolute sign, it is a most valuable point in diagnosis, and should be always remem- bered. In addition to the muscular paralysis, lead poison- ing is often accompanied by muscular atrophy and swell- ing of the veins upon the extensor side of the forearm ; while tendinous swellings are frequently detected in the region of the wrist. The duration of paralysis of the musculo-spiral nerve de- pends largely upon the exciting cause. Lead poisoning pro- duces, in all cases, an exceedingly slow and obstinate form of trouble, and the paralysis may be incurable ; ''crutch paraly- sis" usually recovers speedily, if the pressure be discontinued ; traumatic paralysis, if the injury be severe, follows a protract- ed course ; while those cases which depend upon cerebral origin are modified, as to their course and termination, by the character of the exciting lesion. THE DORSAL NERVES. The nerves of the dorsal region are twelve in number upon each side of the trunk. They escape from the vertebral canal by means of foramina between the dorsal vertebrae, and are connected to corresponding ganglia of the sympathetic nerve. Each dorsal nerve is joined to a ganglion of the sympathetic, immediately after its escape from the foramen between the vertebrae, by two small and short filaments ; hence, there are frequent points of communication between the cerebro-spinal and sympathetic systems of nerves throughout the length of the vertebral column. As has been stated in a previous lec- ture, the first dorsal nerve assists to form the brachial plexus, 420 THE SPmAL NERVES. and can therefore be properly classed as one of the nerves of the upper extremity rather than a nerve of the trunk ; the remaining nerves of this region are distributed entirely to the parietes of the thorax, the adjacent pleura, and the in- tegument covering the front, sides, and back of the chest, and the upper part of the abdomen. The table which I now show you is designed to make the general distribution of the dorsal nerves easy of comprehen- sion, and to assist in reviewing the chief points of interest which are presented in connection with the nerves of this region. NERVES OF THE DORSAL REGION. Posterior divisions. DORSAL , NERVES, i Anterior \^ divisions. External , branches. ' Infernal branches. Six upper or thoracic intercos- tals. oix lower or tlioracico- j abdomi- nal inter costals. In upper six nerves. In the lower six nerves. In upper six nerves. In the lower six nerves. Muscular branches. Lateral cutane- ous. Anterior cutane- ous. Muscular branches. Lateral cutaneous. Anterior cutaneous. Filaments to transvcrsalis colli, Filaments to longissimus dorsi, Filaments to tvachelo-mastoid, Filaments to levatores costarum, Filaments to sacro-lumbalis, Filaments to accessorius. Same muscles as in preceding; bracket, Integument of the back. Filaments to semispinalis dorsi, Filaments to multifidus spinae. Integument of back. Same muscles as in preceding bracket, No cutaneous filaments. Intercostals, Triangularis sterni. Integument of chest and mammte, Upper part of external oblique muscle. Integument over upper part of latis- simus dorsi and the scapular re- gion. Integument of mammae and side of the chest. Intercostals, Abdominal muscles. Integument of abdomen, as far as the edge of rectus. Integument over lower part of latis- simus dorsi. Upper 'part of rectus and integv- ment in front part of abdomen. It will be perceived that these nerves, like those of the cervical region, divide into anterior and posterior branches, in the immediate vicinity of the vertebral column. The pos- terior divisions supply the muscles of the back and the in- BISTRIBUriON OF THE DORSAL NERVES, 421 I .tegument which covers that region, while the anterior divis- il ions supply the muscles of respiration and some of the Fig. 158. — The intercostal Jicrves. (Masse.) The pectoralis major and minor muscles are removed. The obliquus externus and rectus abdominis are divided, and removed in some places. 1, axillary vein : the artery js removed ; 2, portion of the bi*achial plexus and two tho- racic branches ; 3, brachial twii^ of the first intercostal nerve ; 4, brachial twig of the second intercostal nerve ; 5, inosculation between two branches ; 6, division of an intercostal branch into 7, a superficial branch, and 8, a deep branch ; 9, gluteal branch of the twelfth intercostal nerve ; 10, termination of the ilio-scrotal branch of the lumbar plexus ; 11, mgulno-cutaneous branch; 12, twig of the genito crural branch; 13, 13, portions of the deep nerves after they have become superficial. abdominal muscles, and the integument of the chest, loins, and abdomen. The intercostal nerves are formed entirely 29 422 THE SPINAL NERVES. from the anterior divisions ; those arising from the upper half of the dorsal region being called the ''thoracic " intercos- tals, while the lower six nerves are called the "thoracico- abdominal" intercostal nerves. The first and last dorsal nerves are somewhat peculiar in their distribution, and deserve a special description. The first dorsal nerve has no lateral cutaneous branch, since the branch which corresponds to the lateral cutaneous branch of the other nerves is of large size, and enters into the formation of the brachial plexus. The continuation of this nerve along the first intercostal space is of small size, and ends in the an- terior cutaneous nerve. The last dorsal nerve is the largest of the twelve, and is usually connected with the first lumbar nerve by a filament called the " dorso-lumbar " nerve, which descends in the substance of the quadratus lumborum muscle. It com- municates also with the hypogastric branch of the ilio-hy- pogastric nerve (a branch of the lumbar plexus), between the internal oblique and transversalis muscles of the ab- domen. Its lateral cutaneous branch is very large, and is distributed to the integument of the front part of the gluteal region. The distribution of the dorsal nerves to the costal layer of the pleura is not specially designated in the table,' but it is a fact of great physiological interest. Hilton draws an analogy between the pleura and a synovial membrane of a joint ; and the intercostal muscles are also compared by him to those moving a joint. Thus this author adduces further proof of his general law of nerve distribution, since the skin of the chest, the intercostal muscles, and pleura are supplied from the same source. In pursuing this same line of reasoning (and the analogy is not a strained one from a physiological standpoint), the abdominal muscles might also be included among the list of muscles which move the ribs ; and the nerve supply to them also would thereby be explained by this same axiom, viz., that the nerves which supply a joint supply the ^ See page 420 of this volume. DISTRIBUTION OF THE DORSAL NERVES, 423 muscles which move it and the skin over the insertions of those muscles. It should be recollected that some of the filaments derived Fig. 159. — The nerves situated on the posterior part of the trunk. (Masse.) Portions of the trapezius, splcnius, complexus, trachelo-raastoideus, latissimus dorsi, and gluteus maximus muscles, etc., etc., are removed. 1, 1, 1, posterioi' twigs of the superficial branches of the intercostal nerves; 2, posterior branch of the first cervical nerve, or sub-occipital ; 3, posterior branch of the second cervical nerve ; 4, inosculation of this branch with the great mastoid branch ; 5, 5, posterior branches of two cervical nerves ; 6, intercostal branch ; 7, external twig of a dorsal branch ; 8, internal twig of a dorsal branch ; 9, posterior brajich of a lumbar nerve ; 10, posterior branch of a sacral nerve. 424 TEE SPIXAL NERVES. from the upper intercostal nerves cross the axillary space and supply the integument of the arm. The ''nerve of Wris- berg," which has been described in connection with the cuta- neous nerves of the arm, is perhaps the most important of these branches. It may thus be understood why the pain of pleuritic inflammation may be carried to and felt in the region of the axilla and inner arm, and why distinct points of tender- ness to pressure may sometimes be detected in these regions when the disease is confined to the trunk. CLINICAL POINTS PERTAINING TO THE DORSAL NERVES. From the suggestions thrown out as to the physiological importance of nerve distribution, and from the fact that the pleura is supplied from the same nerve sources as the respira- tory muscles and the integument of the chest, abdomen, and inner arm, some important clinical lessons may be drawn. Patients suffering from pleurisy feel a pain in the costal muscles which compels restricted movement of the ribs, and which limits the respiratory function largely to the diaphragm. Now, these painful cramps and stitches are independent of the pain arising alone from the inflamed pleural surface, and the diminution of the resj^iratory movements is due to a par- tially contractured state of the muscles of the chest, as is de- monstrated by the fact that patients can not draw a long breath if asked to do so ; hence, we may reasonably conclude that Nature has so distributed the nerves to the pleura as to en- able that serous membrane to control the muscles which create movement of the adjacent costal surfaces, and thus insure its quietude during the stages of inflammation or repair. It is wisely suggested by Hilton, in this connection, that we learn a lesson in the treatment of such cases from Nature herself, viz., '' never to allow a patient, suffering from pleurisy or pneumonia, to talk except in monosyllables, so as to avoid a full inspiration." The diagnostic value of pain is well exemplified in the region of the thorax. Persistent pains Mgh up between the shoulders are strongly indicative of diseases of the heart, CLINICAL POINTS AFFORDED BY THE DORSAL NERVES 425 aneurism of tlie arch of the aorta, stricture of the oesophagus, and anything which would tend to create pressure within the 11 Fig. 160. — A diagram, of the regions of ciUaneous nerve distribution in the anterior sur- face of the upper extremity and trunk. (Modified from Flower.) 1, region supplied by the supra-clavicular nerve (branch of the cervical plexus) ; 2, re- gion supplied by the circumflex nerve ; 3, region supplied by the intcrcosto-humeral nerve; 4, region supplied by the intercostal nerve (lateral branch) ; 5, region sup- plied by the lesser internal cutaneous nerve (nerve of Wrisbcrg) ; 6, region supplied by the musculo-spiral nerve (external cutaneous branch) ; 7, region supplied by the internal cutaneous nerve ; 8, region supplied by the musculo-cutaneous nerve ; 9, region supplied by the median nerve ; 10, region supplied by the ulnar nerve ; 11, region supplied by the intercostal nerve (anterior branch). posterior mediastinum/ If we meet with persistent pain in the space lying between the middle of the scapula and the ^ John Hilton, op. cit. 426 THE SPINAL NERVES. lumbar region of the spine^ we may have good ground to sus- pect the existence of some disease of the abdominal digestive viscera, the pain being carried to the surface probably by oneans of the splanchnic nerves.' It is not uncommon for disease confined to the transverse colon to manifest itself in the form of persistent pain in the lower intercostal region. The frequent occurrence .of cancer in the mammary region renders its detection one of importance in its early stages, while, in the later stages, the pleura and the glands of the axilla and mediastinse may be secondarily affected with can- cer tubercles. Now, in these conditions, the presence of pain in the back, between the shoulders, in the side of the chest, or down the inner side of the arm, may possibly afford invalu- able aid in diagnosis. The distribution of the sixth and seventh intercostal nerves to the skin over the pit of the stomach may be a useful fact to remember in making a diagnosis of the cause of pain in that region, since, by tracing the course of these two nerves from before backward, and observing the healthy or unhealthy con- dition of the structures near to which the nerves would pass — as the pleura, ribs, oesophagus, aorta, etc. — we may at last reach the spine as the seat of the disease which is producing pain in a region far remote from the cause to which it is really due. It is by no means uncommon for spinal affections of the mid-dorsal region to manifest themselves by a pain Avhich is distressing, and referred to the pit of the stomach ; and such an origin is rendered still more probable if present on both sides of the median line, since symmetrical pains are especially characteristic of central origin." Should such a pain exist, and a marked relief ensue when the patient is in a recumbent posture, the probability of spinal origin is still more distinctly suggested. ^ The great splanchnic nerve is -connected above with the fourth, fiftli, and sixth dorsal nerves, and below with the solar plexus and thence with the stomach, duodenum, liver, pancreas, and intestines. It seems probable, therefore, that the pain experienced in the region of the scapula, by patients afflicted with diseases of the digestive organs, is refer- able in some way to the greater splanchnic nerve. 2 The reader is referred to the general axioms of nerve distnbution, quoted on pages 359, 360, and 361 of this volume. THE INTERCOSTAL NERVES. 427 It lias been stated in previous lectures that pains which are confined to one side of the body are usually indicative of an exciting cause which is confined to the same side, rather than of diseased conditions of the central nerve ganglia. It is therefore customary, with those most familiar with the steps necessary to reach a scientific diagnosis, to search for some cause upon the same side of the body, in case a pain exists which is not symmetrically developed upon both sides. I have known the diagnosis of aneurism within the thorax to be discovered by a pain, which was one-sided, and which was the only symptom which the patient was conscious of, where the existence of the tumor would probably have gone on un- detected but for this valuable guide. A constant pain in the back is one of the most positive signs of aneurism of the coeliac axis, and 1 question if the diagnosis of aneurism of the abdom- inal aorta in any part of its course should ever be made unless this symptom can be detected. Pain in the region of the pectoral muscle may indicate some cause referred either to the third or fourth cervical or the first dorsal nerves ; hence we must look in two different localities for the exciting lesion. The distribution of the cervical nerves to the fascia covering the anterior portion of the chest is not sufficiently well recognized by the profession at large, and doubtless many cases have been a source of anxiety to the physician which could have been easily explained, had this point been impressed upon them. The distribution of the lower intercostal nerves to the in- tegument covering the upper part of the muscles of the abdo- men may be useful in diagnosis, since pain in this region of the abdomen may be created by pressure of fluid in the pleural cavities, and by other lesions situated above the line of the diaphragm. It is not improbable, therefore, that many cases of this character have misled the medical attendant who has referred the symptom of abdominal pain to organs within the cavity of the abdomen, when the exciting cause was to be sought for within the chest or in the course of the lower intercostal nerves \ Certainly, successful treatment depends upon accu- 428 THE SPINAL NERVES. racy in diagnosis ; and the application of the laws of nerve distribution to fine discriminations in the appreciation of symptoms is a guide whose value and utility are not generally known. When we have our attention called by a patient to a pain, no matter where its situation may chance to be, we are positive that it can be traced to the nerves supplying the part. Here, then, we have a direct guide to follow which will usually lead us, if we are anatomists, to the source of the pain. As an ex- ample of this, and they are too numerous to mention in detail, there is one symptom in spinal disease which stands out prom- inently, and I might say solicits our proper appreciation of it, and that is a fixed and local pain upon the surface of the body, with or without exacerbations, and often without any local in- crease of temperature at the seat of the disease. I feel quite certain that through the medium of this one symptom alone, if properly employed, morbid conditions of the vertebrae or the spinal cord, its membranes, and its nerves, may be often diagnosed long before any palpable deformity of attitude or gait exists, and a cure often effected by simple rest. It is in connection with the nerves of the dorsal region that pain is a more valuable guide than in almost any other portion of the body. The subjacent viscera, occupying the thoracic and abdominal cavities, are constantly manifesting diseased conditions by pain of a superficial character (through the in- timate communications which exist between the splanchnic •and dorsal nerves) at spots often far removed from the excit- ing cause. It is natural that the medical attendant, unless his attention has been directed to this fact, should attribute the pain to some fanciful cause in the locality of that pain, or to some general diagnosis of neuralgia, malaria, etc., when an anatomical knowledge might direct him aright both in diag- nosis and treatment. We know that liver disease may be oc- casionally manifested by a pain in the region of the right shoulder ; that gastric and intestinal disorders frequently pro- duce a constant pain in the back between the scapulae ; and that tumors of the viscera may produce like results by press- THE INTERCOSTAL NERVES. 429 lire upon the splanchnic nerves or the solar plexus of which they form a part. Without such a knowledge and its satis- Fig. 161. — A diagram of the regions of cutaneous nerve distribution on the posterior sur- face of the upper extremity and trunk. (Modified from Flower.) 18, region supplied by the second dorsal nerve ; 19, region supplied by the supra-scapular nerve; 20, region supplied by the circumfez nerve ; 21, region supplied by the intei'- costo-humeral nerve ; 22, region supplied by the external cutaneous nerve ; 23, region supplied by the internal cutaneous branch of the musculo-spiral nerve ; 24, region supplied by the " nerve of Wrisberg " ; 25, region supplied by the lateral branches of the intercostal nerves ; 26, region supplied by the intavial cutaneous nerve ; 27, re- gion supplied by the musculo-cutaneous nerve ; 28, region supplied by the iliac branch of the ilio-inguinal nerve ; 29, region supplied by the radial nerve ; 30, region sup- plied by the ulnar nerve. factory explanation, would we be apt to refer such pain to causes so remote ? Would we look for causes of abdominal 430 'ISE SPINAL NERVES. pain in the region of the thorax, without the knowledge that the lower intercostal nerves supplied the abdominal muscles \ The lessons taught by anatomy are of a most practical char- acter, and worthy of the study even of those old in the prac- tice of physic. If a patient complains of pain on the surface of the body, it must be expressed by the nerve which resides there ; there is no other structure that can express it, and somewhere in its course of distribution, between its periph- eral filaments and its central point of origin from the enceph- alon or the spinal cord, the precise cause of this pain ex- pressed upon the surface must be situated. INTERCOSTAL NEURALGIA. Those forms of neuralgia which have their seat in the nerves which arise from the dorsal region of the spinal cord are grouped under the term "dorso-intercostal" neuralgia. The exact seat of the pain varies not only with the special nerve affected, but also with the branch of the nerve which seems to manifest the most irritation. Thus, if the upper two nerves are involved, the pain may extend to the arm as well as the trunk ; if the posterior branches of the dorsal nerves be alone involved, the pain will be perceived in the back and loins ; and, finally, if the anterior branches be alone the seat of pain, it will be confined to the intercostal spaces and the anterior region of the chest. It is rare to find the anterior and posterior branches of any dorsal nerve simulta- neously affected with neuralgia. The anterior branches are usually the ones which suffer, and the pain assumes a type which is properly called ''intercostal." Intercostal neuralgia is more common in women than in men, and chiefly affects weak, hysterical, and ansemic sub- jects. It appears often in those who are convalescing from some severe type of disease. The causes to which this fomi of neuralgia can be traced include exposure to cold or damp- ness, anatomical changes in the nerves themselves, diseases of some of the adjoining organs (especially in connection with phthisis), embarrassment to the venous return of the affected INTERCOSTAL NEURALGIA. 431 region, dilatation of the venous plexuses of the interior of the vertebral canal, aortic aneurisms (which lead to absorption of the vertebrae or ribs), all possible diseases of the vertebrae themselves, and also of the ribs, diseases of the spinal cord, and malarial affections. This form of neuralgia is most common upon the left side, and Henle has attributed this clinical fact to the arrangement of the intercostal veins of the left side, ' which relatively tends to impede the return of blood upon the left in contrast to the right side. From the extensive list of causes which have been given — and many of the subdivisions of each have been omitted — it can be readily understood that, to make an accu- rate diagnosis as to the etiology of intercostal neuralgia, is never possible without a most thorough physical examination of the subjacent organs, the bones of the thorax, and the con- ditions of the soft tissues. The symptoms of this disease are generally confined to the anterior and lateral walls of the trunk, more rarely to the tack and the loins. The area of the pain indicates the nerves effected, which is often a point of great value in searching for the cause. While the pain is of a burning, dull, and persist- ent character for the greater part, yet it is often characterized by paroxysms of tearing and lancinating pains which follow the course of the nerves affected with a remarkable precision. The violence of these paroxysms may be very great, so as to cause syncope. All respiratory motions, such as sneezing, coughing, blowing the nose, etc., increase the pain, and the skin is sensitive to the slightest pressure, even the weight of the bedclothes distressing the patient, although firm pressure may sometimes afford relief. While the paroxysm is active, the patients sit with the body inclined toward the affected side, and their faces indicate the most extreme anxiety. They neither dare to speak loudly nor take a deep inspira- tion, on account of the pain induced by such efforts. ' The intercostal veins of the left side empty into the left superior intercostal vein or the left vena azygos ; in cither case, the blcod takes a circuitous route to the superior vena cava. 432 THE SPIXAL KERVES. In intercostal neuralgia, as in most other forms, there are certain points which are particularly sensitive to pressure, and are of great aid in confirming the diagnosis. These points comprise, first, one near to the vertebral column {verte- bral point\ where the nerve emerges from the inter- vertebral foramen ; secondly, one at about the middle of the entire course of the nerve, corresponding to a line dropped from the center of the axillary space {lateral point), where the lateral branch emerges beneath the integument ; and, thirdly, one in front, near to the sternal border {anterior or sternal point\ where the anterior perforating branch emerges be- neath the skin. For some unknown reason, the intercostal nerves, when inflamed, are particularly liable to be associated with the appearance of that form of skin disease called "herpes zos- ter." This may or may not be accompanied by neuralgic symptoms, but it is a valuable sign of a neuritis of the nerves supplying the region affected. The diagnosis of intercostal neuralgia can often be made only with extreme difficulty. That rheumatic affection of the muscles of the chest commonly called " pleurodynia" is often confounded vdth it, and . the diagnosis is to be made chiefly by the presence of the localized points of tenderness mentioned, and the rapid disappearance of all symptoms in the course of a few days, which is seldom observed in true intercostal neuralgia. Pleurisy is also to be differentiated from this disease chiefly by its physical symptoms ; and an- gina pectoris is to be told by the phenomena presented by the heart and the pulse, as well as by the sense of impending death, threatened suffocation, intense anxiety, and the fact that the pain frequently shoots down the left arm. NEUEALGIA OF THE MAMMARY GLAND (mASTODYXIA). The skin over the mammary gland is supplied by the an- terior and lateral branches of the second, third, fourth, fifth, and sixth intercostal nerves, and by some filaments derived from the supra-clavicular nerves, while the glandular struct- PARALYSIS OF THE DORSAL NERVES 433 lire itself is supplied by the lateral perforating branches of the fourth, fifth, and sixth intercostal nerves. This region is (SiDecially liable to an extreme form of neuralgia, first de- scribed by Sir Astley Cooper under the name of "irritable In-east." So intense is the pain in some cases of this affection that it is compared to the sensation of cutting, tearing, or stabbing the part with a knife. It is usually paroxysmal in character, and generally of short duration, although such attacks may last for some hours. This affection seems to be associated with pregnancy, anaemia, chlorosis, hysteria, and the development of neu- romata upon the nerves of this region. It may be persistent and remain for years, and is particularly obstinate to treat- ment. The detection of painful points is to be looked for in the region of the escape of the nerves which supply the part from the inter- vertebral foramina ; and, in some instances, the ex- istence of similar points may be detected upon the breast, near the nipple, and upon the sides of the gland. The at- tacks are particularly liable to exacerbate during the men- strual periods, and, during the height of the paroxysm, the pain may be transmitted by other nerves into the neck, down the arm, and over more extended areas upon the chest and back. PAEALYSIS OF THE DORSAL NERVES. The dorsal muscles control, to a great extent, the move- ments, fixation, and upright position of the vertebral column, but these conditions require such a complexity of muscular action that it is often difficult, in case of paralysis, to exactly decide as to the muscles which are affected. Various degrees of weakness of the dorsal muscles are often present in youth, sometimes on one side and sometimes on the other, and oc- casionally affecting the whole back to a greater or less ex- tent. These paretic states are dependent upon rheumatic affec- tions, diseases or injuries of the vertebral column, disturb- ances of the motor regions of the cerebrum, lesions of the 434 TEE SPINAL NERVES. various ganglia of the encephalon, and lesions of the kinesodic system of the spinal cord. In paraplegia, the motor paralysis often extends upward to the muscles of the trunk ; while, in progressive muscular atrophy, the muscles of the dorsal region are not infrequently involved. If the muscles of both sides of the back be paralyzed, the spinal column gradually tends to assume the condition of a posterior curvature (paralytic kyphosis), and the deformity is usually most marked in the dorsal region, as the lumbar and cervical regions exhibit it to a less degree on account of their anatomical peculiarities. If the extensor muscles of the back be markedly affected, the spinal column forms an equable curve, as if the body were bent forward as in old age, and the patient becomes unable to voluntarily straighten the trunk to its normal posture. When passive straightening is attempted, the spine is easily brought into its proper curve ; and this is a point of diagnosis between paralytic kyphosis and the de- formity dependent upon structural disease of the vertebrae or a state of muscular contracture. The muscles most frequently affected are the sacro-lum- balis and the latissimus dorsi. If they be paralyzed upon one side only, the deformity assumes the type of scoliosis, as a lateral curvature is produced by the muscles of the unaffected side. In this case, as in the one before cited, the patient is unable to rectify the deformity by any voluntary muscular effort, although the spinal curve can be easily removed by mechanical aid. When the extensor muscles of the lumbar region are markedly impaired, the attitude assumed by the patient is very characteristic. It consists of a bending of the upper portion of the trunk in a backward direction, so as to com- pensate for the bending forward of the lumbar vertebrse ; this bending of the thorax backward brings the upper part of the body behind the center of gravity of the whole body, and the balance is preserved exclusively by the action of the muscles of the abdomen. ^Vhen the body is brought too far forward, it sinks and falls, as the lumbar muscles fail to support it in P ABA LYSIS OF TEE DORSAL NERVES 435 an erect posture. The patient can not then bring the trunk into its former posture without the use of the hands, which are employed in a sort of a climbing process, the hands being Fig. 162. — llie lumbar plexus. (Hirschfeld.) lumbar and sacral portions of the great sympathetic ; 2, twelfth dorsal pair ; 3, first lumbar pair ; 4, 4', ilio-hypogastric branch ; 5, 5', ilio-inguinal branch ; 6, second lumbar pair; 7, origin of the geni to-crural branch; 7, this same branch appearing and descending in front of the psoas muscle ; 8, origin of the external cutaneous nerve; 8', this same branch leaving the border of the psoas, and dividing at the level of the fold of the groin ; 9, third lumbar pair ; 10, fourth lumbar pair ; 11, fifth lumbar pair ; 12, lumbo-sacral trunk ; 13, gluteal branch of the iliohypogastric ; 14, its abdominal branch ; 15, its genital branches ; 16, external cutaneous passing under Poui)art's ligament, between the anterior superior and inferior spines of the ilium ; 17, 17, 17, divisions of this branch; 17', point of origin of these divisions ; 18, 18', genital branch of the genito-crural nerve; 19, 19, femoral division of this nerve piercing the fascia lata in the neighborhood of the saphenous opening ; 19', this division exposed at the fold of the groin, to show its relations with the femoral artery and the saphenous vein; 20^ 20', anterior crural nerve; 21, 21', obturator nerve. placed upon the legs ; a series of peculiar movements of the shoulders and trunk then follow, which are employed to assist 436 TEE SPINAL NERVES. the arms in tossing tlie trunk backward to an extent sufficient to allow the abdominal muscles once more to support it. This difficulty in bringing the trunk above the level of the lower limbs is typical of this condition, but there are still other ad- ditional points of diagnostic value. The lumbar region pre- sents a deep hollow ; the head is bent forward in standing or walking ; and the trunk may be seen to have a remarkable oscillating movement when the patient walks. When the patient sits down, the upper portion of the body seems to sink, and the spine presents a condition of kyphosis. In fact, it seems hardly possible that the condition can be mistaken by one well versed in anatomy. THE LUMBAK NERVES. The lumbar nerves comprise five pairs which escape from the intervertebral foramina of that region. Like all the spi- nal nerves, they each divide, immediately after their escape, into anterior and posterior divisions, the former of which has a larger proportion of motor, while the latter has an excess of sensory fibers. These nerves are of special interest, from the fact that the anterior divisions of the four upper nerves assist to form the lumbar plexus. This plexus is situated in the substance of the psoas muscle, in front of the transverse pro- cesses of the lumbar vertebrae. It is narrow above, where it is joined to the last dorsal nerve, but below it becomes broad, and is connected with the sacral plexus by means of the lumbo-sacral cord and a filament from the fourth lum])ar nerve. The table which I now show you will give you an opportunity of contrasting the relative arrangement of the anterior and posterior divisions of the lumbar nerves, as well as of studying the origin of the seven main nerve trunks given off from the lumbar plexus. In the following table the formation of the lumhar plexui is shown, as well as the branches which are given off from each nerve which assists to form it. THE LUMBAR NERVES. 437 TABLE OF THE XEKVES OF THE LUMBAR REGION. r External \ branches. Posterior divisions. 1st Lumbar nerve. Lumbar j NERVKS. ] Anterior divisions Interned branches. 2d Lumbar nerve. 3d Lumbak nerve. 4th Lumdak nerve. ( Filaments to erector spinae muscle, I Filaments to the inter-transversales ^ muscles, I Filaments to integument of back part [ of gluteal region. Filaments to multifidus spina? muscle, Filaments to integument near spinal column. [' Ilio-hypogastric nerve, ^ Given off by Lumbar Plexus. Ilio-inguinal nerve, Communicating to 2d lumbar. Genito-crural nerve, External cutaneous nerve. Communicating to 3d lumbar. J Part of anterior crural ^ nerve, Part of obturator | nerve, ! Part of accessory ob- f turator nerve. Communicating to 4lh lumbar. Part of anterior crural nerve, Part of obturator nerve, Part of accessory ob turator nerve, | Lumbo-sacral cord. J the 1st LUMBAR NERVE. Given off by the 2d LUMBAR NERVE. Given off by the 3d LUMBAR NERVE. Given off by the 4th ^ LUMBAR NERVE. It will be perceived that three most important nerves, viz., the anterior crural, the obturator, and accessory obturator nerves, are formed by branches both of the third and fourth lumbar nerves, and therefore may be said to arise by two heads. The accessory obturator nerve, however, arises occa- sionally by a branch derived only from the fourth lumbar nerve, its other head being a branch given off from the obtu- rator nerve. The second table, to which I now call your attention, is constructed to show the distribution of each of the seven large branches of the lumbar plexus. This table may aid in refreshing your memories while following the subsequent lectures, while it also gives you, at a glance, a better concep- tion of the arrangement of any special nerve than a mere verbal description. ^ Taken from " The Essentials of Anatomy " (Darling and Panney). New York : G. P. Putnam's Sons, ICSO. 30 438 THE SPmAL NERVES. TABLE OF THE DISTRIBUTION OF THE BRANCHES OF THE LUMBAR PLEXUS.» Iliac branch. ■{ Inte(jument of gluteal region. yPy^ ' \ -j Integument of the hypogastric region. Internal oblique muscle, Integument of upper and inner portion of thigh, Integument of scrotum, Integument of penis, Integument of labium. Crcrnaster muscle, Scrotum, f (1) Ilio-hypo- _ I GASTRIC. (2) Ilio-ix- GUINAL. Lumbar PLEXUS. (3) Genito- CRURAL. (4) External cutaneous. Genital branch. Crural branch Anterior branch. Posterior branch. ' Anterior division. ■< (5) Anterior CRURAL. Internal cuta- neous nave Posterior division. (6) Obtura- tor NERVE. (7) Accessory NERVE . . , Anterior branch. Posterior branch. Obturator Round ligament of female. Iniegument of the front and upper portion of the thigh. \ Integ}iment on the anterior and outer as- ) pect of thigh, as low as the knee. j Integument of the posterior and outer as- { pect of the thigh. fThe sartorius muscle. Middle cuia- J Integwiicnt of anterior as- neous nerve. \ spect of thigh, as low as the knee. (Integument of External J inner and branch. | outer sides (^ of knee. (Integument of Posterior J inner sides branch, j of the thigh (^ and the kg. Long or intci'- ( Integument of knee joint nal saphe- ■< and front and inner nous nerve. ( sides of the leg and foot, f fAU the muscles on front of thigh except the ten- sor vagince femoris and the sartorius. Two in number. Distribu- ted to capsule of knee joint, and probably to the hip joint. ^^''\tLhes. [to /„>>,.. {To gracilis. To adductor longus, To pectineus, To adductor brevis. With internal cutaneous nerve. With internal saphenous (^ nerve. branches.] To >?n^^>"'^ Muscular \ Obturator extcrnus, branches, j Adductor magnus. Muscular j ^^ ^ineus. branch. ( '^ Articular \ m„ i-^ j:^:^* branches. jT*'^^^^^'"'^- Cutaneous \ To the integument of branches. ( tliigh and leg. Mv^ailar branches. Articular branches. Anastomotic branches. Articular ^ Taken from " The Essentials of Anatomy " (Darling and Ranney). P. Putnam's Sons, 18S0. Xew York : G. BRANCHES OF THE LUMBAR PLEXUS. 439 THE ILIO-HYPOGASTRIC NERVE. This nerve is named, from its two terminal filaments of distribution, the iliac and hypogastric branch. It is given off by the first lumbar nerve in company with the ilio-inguinal. It emerges from the outer border of the psoas muscle, crosses the quadratus lumborum, then perforates the transversalis muscle of the abdomen, and finally divides between it and the internal oblique muscle into its iliac and hypogastric branches. The iliac hrancJi pierces the internal and external oblique muscles just above the crest of the ilium, and supplies the skin of the gluteal region, while the hypogastric branch pierces the internal oblique and the aponeurosis of the ex- ternal oblique muscle a little above the external abdominal ring, and supplies the skin of the hypogastrium. In some cases the ilio-inguinal nerve is incompletely developed, and this nerve may then be traced downward to the skin of the penis, scrotum, labium, and thigh. THE ILIO-IXGUIN^AL KERVE. This nerve arises, in common with the preceding nerve, from the first lumbar nerve, but it is smaller in point of size than its fellow. Like the ilio-hypogastric, it pierces the outer border of the psoas, and crosses the quadratus lumborum muscle, lying below the preceding nerve ; it then pierces the transversalis muscle, enters the inguinal canal, passes through- out the entire length of that canal in front of the spermatic cord, and supplies the skin of the penis, scrotum, labium, and of the upper and inner portions of the thigh. It is some- times incompletely developed, in which case the ilio-hypogas- tric nerve takes its place. CLIIflCAL POINTS PERTAINING TO THE ILIO-HYPOGASTRIC AND ILIO- INGUINAL NERVES. These two nerves are sometimes the seat of a severe form of neuralgia. It may be produced by disease of the lumbar 440 THE SPINAL NERVES. vertebrae, structural changes in the parts investing the lum- bar plexus, pelvic diseases, exudations in the substance of the psoas muscle, strains, contusions, exposure, and an hys- terical condition. The pains are usually of a paroxysmal character, and radiate in the course of these nerves ; they are of a lancinating type, and often extremely severe. Painful points may be detected in one of the following regions, or possibly in all of them : 1, a lumbar point .^ near the spinous processes of the lumbar vertebrae ; 2, an iliac point, near to the middle of the crest of the ilium, where the ilio-hypogas- tric nerve pierces the transversalis muscle ; 3, an liypogastric pointy slightly above the external ring, where the ilio-hypo- gastric nerve pierces the aponeurosis of the external oblique muscle ; 4, an inguinal point ; and 5, points upon the scrotum or labium. It is stated by ^N'otta ' that this type of neuralgia may be occasionally accompanied by an increase in the sexual appetite, and a spasmodic contraction of the cremaster muscle. This form of neuralgia is to be diagnosed from rheumatic myalgia of the longissimus dorsi and sacro-lumbalis muscles, and from those types of chronic affections of the uterus which induce pain in the back. It might also be possibly mistaken for an attack of renal or biliary colic. The diagnosis will be made chiefly by the ''puncta dolorosa " ' previously described, by the course of the pain, and by its intense paroxysmal and lancinating character. The nerves which are distributed to the skin of the ab- dominal walls may be considered as comprising two distinct sets, based on the physiological action of the abdominal mus- cles which are supplied by them. According to Hilton, the abdomen may be divided, on a line corresponding with the situation of the umbilicus, into an upper or respiratory por- tion, and a lower or abdominal portion. The uj^per or respi- ratory portion is supplied, in great part, by the lower inter- costal nerves, which are distributed also to the muscles of the ' As quoted by Erb. ' A name applied by Valleix to the spots of extreme local tcnderaess found along the course of a nerve which is the seat of neuralgia. THE EXTERNAL CUTANEOUS NERVE. 44,1 chest, and which, if taken with the other intercostal nerves as a group, are essentially respiratory in their function. The lower or abdominal portion of -the abdomen is supplied chiefly by the ilio-hypogastric nerve, although the ilio-inguinal, the genito-crural, and the posterior branches of the lumbar nerves assist in furnishing motor power to the muscles of that region. The subjacent peritonaeum is unquestionably supplied from the same sources of nerve power as the muscles and skin of the individual regions of the abdomen, and it is considered probable by the author above quoted that the spinal nerves which are distributed to the skin, muscles, and parietal peri- tonaeum may be also associated with the visceral layer under- neath, by means of communications with the sympathetic nerve. The abdominal muscles unquestionably assist the co- lon in its endeavors to force the faeces, by its peristaltic action alone, throughout its length, since the force of gravity has to be overcome in its ascending portion, and the curves of the sigmoid flexure in its terminal portion. It would therefore be an additional confirmation of a general law of nerve dis- tribution, provided the distribution of the abdominal nerves to the intestinal covering of peritonaeum could be fully veri- fied ; since the structures which assist in moving the adjacent organs — the abdominal muscles — would be supplied from the same source as the parts moved, as well as the skin over those muscles. THE EXTERN-AL CUTANEOUS NERVE. This nerve arises from the trunk of the second lumbar nerve, in common with the genito-crural, but it usually re- ceives a few filaments from the third lumbar. It pierces the psoas muscle, near to its central point, and crosses the iliacus muscle in order to reach a notch below the anterior superior spine of the iliam, where it escapes below Poupart' s ligament. The anterior branch of this nerve pierces the fascia lata at about four inches below Poupart' s ligament, and supplies the integument of the anterior and outer aspects of the thigh, while the posterior branch supplies the integument of the outer and posterior aspects of the same region. Both of these 442 THE SPINAL NERVES. terminal branches are given off after the main nerve trunk has escaped from beneath Poupart's ligament. It will be observed that this nerve pierces the psoas muscle in a different direc- Fig. 163. — The cutatieous nerves of the thigh. (Ilirschfeld.) 1, lumbar and sacral portions of the great sympathetic; 2, twelfth dorsal pair; 3, first lumbar pair; 4, 4', ilio-hypogastric branch; 5, 5', ilio-inguinal branch; G, second lumbar pair ; 7, origin of the genito-crural branch ; 7', this same branch appearing and descending in front of the psoas muscle ; 8, origin of the external cutaneous nerve ; 8', tlTis same branch leaving the border of the psoas, and dividing at the level of the fold of the groin ; 9, third lumbar pair ; 10, fourth lumbar pair ;^1 1, fifth lumbar pair; 12, lumbo-sacral trunk ; 13, gluteal branch of the iliohypogastric ; 14, its abdominal branch; 15, its genital branches; 16, external cutaneous nerve passing under Poupart's ligament, between the anterior superior and inferior spines of the ilium ; 17, 17, 17, divisions of this branch ; 17', point of origin of these divisions ; 18, 18', genital branch of the genito-crural nerve; 19, 19, femoral division of this nerve piercing the fascia lata in the neighborhood of the saphenous opening; 19', this division exposed at the fold of the groin, to show its relations with the femoral aitcry and the saphenous vein ; 20, 20', anterior crural nerve ; 21, 21", obturator nerve. tion from the two preceding nerves, and that it crosses over the iliacus muscle, while the two preceding nerves crossed the THE GENITO-CEURAL NERVE, 443 • quadratus lumborum. This fact, wMcli is true also of tlie genito-crural nerve, is to be remembered in tracing the seat of origin of a pain felt in the regions supplied by either of these nerves. We would naturally look, as we pass toward the trunk, either to find the cause of such a pain (manifested by the external cutaneous nerve) in the region of Poupart' s liga- ment, or to detect some pelvic cause involving the iliacus muscle, some abnormal condition of the psoas muscle, or some lesion of the vertebrse in the lumbar region. THE GEXITO-CRURAL NERVE. This nerve arises, in common with the external cutaneous, from the second lumbar nerve, although it occasionally receives some filaments from the first lumbar. It pierces the psoas muscle, and divides into its two terminal branches upon its anterior surface. The genital branch crosses the external iliac artery and passes through the inguinal canal to supply the cremaster muscle and the scrotum or labium ; it lies behind the sper- matic cord in the male and the round ligament in the female. The crural hrancli pierces the fascia lata (after escaping beneath Poupart's ligament on the inner side of the psoas muscle) on the outer side of the femoral vessels, and supplies the skin of the upper and anterior part of the thigh, anasto- mosing with the middle cutaneous branch of the anterior crural nerve. CLIN'ICAL POINTS PERTAINING TO THE EXTERNAL CUTANEOUS AND GENITO-CRURAL NERVES. As both of these nerves are distributed chiefly to the integ- nment, a knowledge of their anatomy affords the intelligent practitioner a means of tracing the situation of any local cause of a pain, confined to the regions which these nerves supply. While their course is snch as to render them less liable to local pressure or injury than the obturator or anterior crural nerves, and while the fact that they are distributed to no muscles (excepting the cremaster) deprives them of much of 444 THE SPmAL NERVES. • the physiological interest which other nerves possess, still it is possible to imagine certain localized conditions of the psoas and iliacus muscles, local swellings in the vicinity of Pou- part's ligament, and possible forms of vertebral disease w^hich might be manifested exclusively through the medium of these nerves. THE ANTERIOR CRURAL KERVE. This is the largest branch of the lumbar plexus. It arises mainly from the third and fourth lumbar nerves, but often receives a fasciculus from the second. In its course, it per- forates the psoas muscle, emerging from it at the lower part of its outer border. It then passes between the psoas and iliacus muscles, and enters the thigh by escaping under Pou- part's ligament about one half inch to the outer side of the femoral artery. Its main divisions (the middle and internal cutaneous and long saphenous nerves) are given off after it enters the thigh. The distribution of each of these terminal branches is shown you upon the table,' but I would call your attention to some points of special interest pertaining to the anterior crural nerve, whic^h will perhaps enable you to ap- preciate the value which some portions of this table pos- sess. The anterior crural nerve supplies nearly all of those mus- cles which are employed in the first effort of progression. As the act of taking a step forward is performed, we flex the thigh upon the pelvis, we extend the leg at the knee, and we slightly evert the foot.' Now, all the muscles which aid us in performing these various movements — the psoas and ilia- cus, the pectineus and sartorius, the four muscles of the quadriceps extensor, and the subcrureus — are supplied by the anterior crural nerve. This nerve also sends branches both to the knee joint and hip joint ; the capsular ligament of the former, as well as that of the latter,' being supplied by fila- ments which can easily be demonstrated by dissection. If we ' See page 438 of this volume. ' John Hilton, op. cit. 2 This fact is not so stated by all of the text-books upon descriptive anatomy, but, nevertheless, I regard it as capable of demonstration. THE ANTERIOR CRURAL NERVE. 445 now consider, in the third place, that the cutaneous branches of this nerve supply the skin of the thigh, and also the re- gions over the two joints mentioned, we are enabled to a2:ain Fig. 1G4. — The mvscuhr branches of the anterior and internal portions of the thigh. (Sappcy.) 1, anterior crural nerve ; 2, branch which it furnishes to the iliacus muscle ; 3, twig which it sends to the internal portion of the psoas muscle : 4, middle cutaneous branch of the anterior crural, whose three branches have been divided close to their origin in order to show the branches to the quadriceps extensor and the internal saphenous nerve, which are more deeply placed ; 5 and 6, muscular filaments of the internal cutaneous nerve ; 7, origin of the cutaneous branches which pierce the fascia lata at the level of the saphenous opening ; 8, deep or anastomotic filament of the internal cutaneous branch of the anterior crural ; 9, branches to the rectus muscle ; 10, branches to the vastus externus ; 11, branches to the vastus internus; 12, 12, inter- nal saphenous nerve; 13, patellar branch of this nerve; 14, its vertical or tibial branch ; 15, obturator nerve ; 16, branch which it furnishes to the adductor longus ; 17, branch to the adductor brevis ; 18, branch to the gracilis ; 19, branch to the ad- ductor magnus ; 20, lumbo-sacral trunk ; 21, junction of this nerve with the first sacral nerve ; 22, 22, lumbar and sacral portions of the sympathetic ; 23, external cutaneous nerve. 446 THE SPINAL NERVES. I'/ 11 i \ \ 7 10 1\ 13 12 '' 14r Fig. 165. — A diaqram of the cuiancous supply of the anterior aspect of the lower extirmiti/. 1, region supplied by the lateral branches of the intercostal nerves; 2, region sup])lied by the anterior branches of the intercostal nerves; 3, region supplied by the ilio-hyix) gastric nerve; 4, region supplied by the ilio-inguinal nerve; 5. region supplied by the genito-crural nerve ; G, region supplied by the middle cutaneous branch of the anterior crural nerve ; Y, region supplied by the internal cutaneous branch of the anterior crural nerve and partly by the obturator nerve ; 8, region supplied by the external cutaneous nerve ; 9, region supjjlied by the long saphenous branch of the anterior crural nerve ; 10, region supplied by the branches of the external popliteal nerve; 11, region supplied by the musculo cutaneous nerve ; 12, region supplied by the terminal filaments of the musculo-cutaneous nerve; 13, region supplied by the external saphenous nerve ; 14, region supplied by the anterior tibial nerve. CLINICAL POINTS OB' ANTERIOR CRURAL NERVE. 447 record a confirmation of that axiom of Hilton/ that a nerve which supplies a joint must supply also muscles which move that joint, and the skin over the insertion of those muscles. The long saphenous nerve seems, at first sight, to extend far beyond the limits of the muscular distribution of the anterior crural, but, when we look closely into the anatomical rela- tions of the fascia of the leg, we find that the muscles sup- plied by the anterior crural nerve are attached to it, especially the sartorius, whose insertion into this fascia is as intimate as that of the biceps into the fascia of the forearm ; and we also notice that the cutaneous distribution over this fascia is derived from the same sources as are the muscles which are attached to it. This fact is in perfect accord with the axiom given in a previous lecture, viz., that a fascia, to which muscles are attached, must be considered as one of the points of insertion of the muscles connected with it, and that the cutaneous distribution over such a fascia will be found to be derived from the nerves which supply those muscles. We thus discover in the lower extremity the same general laws of nerve distribution, as were verified in connection with the upper extremity, fully carried out ; and it is thus that many of the apparent deviations from the natural order of nerve supply may be explained by, and often act as guides to, the presence of some anatomical fact, whose physiological impor- tance had either not been recognized or properly appre- ciated. CLINICAL POINTS PERTAINING TO THE ANTERIOK CRURAL NERVE. The relation of this nerve to the femoral artery as it passes underneath Poupart's ligament and its still more intimate re- lation with that vessel in Scarpa's space render it of special interest to the surgeon. Its internal cutaneous branches cross the upper part of the femoral artery in that space, be- fore it becomes properly a cutaneous nerve ; while the long saphenous nerve lies to the outer side of that vessel for nearly its entire length, being at first slightly removed fromx it, but ' Op. cit. 448 THE SPINAL NERVES, approaching it more closely in the lower part of its course. This latter nerve also bears an intimate relation with the in- ternal saphenous vein for the greater portion of its course ; hence the pain experienced from varicose veins in this region. ' It is customary with surgeons to regard a pain which is localized at the iniier side of the knee (since the obturator nerve is distributed to that region) as strongly diagnostic of disease of the hip joint, because that nerve is supposed to have an intimate connection with the internal structures of the hip. So strongly is this impression grounded in the minds of some of our prominent surgical authors that the presence of pain in any other locality than that just mentioned is not con- sidered as particularly indicative of morbus coxarius ; and the inference is certainly implied, if not directly stated, that the accuracy of diagnosis of this condition can be questioned if this symptom be not confined to the region supplied by the obturator nerve. I am not prepared to* admit that pain in the knee is always present in morbus coxarius, nor am I inclined to think that the anterior crural nerve, from its distribution to the capsular ligament of the hip joint, can not also be one of the sources of sympathetic pains referred to the knee, in case the hip be diseased. I admit that the obturator nerve, from its distribution to the internal structures of the hip joint,' is the most frequent source of transmission of these sympa- thetic pains ; but the sciatic and anterior crural nerves may also indicate an irritation of their filaments to the capsule of the hip by pains referred to the other regions which they supply. Spasm of the quadriceps extensor muscle, which is sup- plied by the anterior crural nerve, is often observed in artic- ular neuralgia of the knee joint ; >vhile the rigid extension of the leg upon the thigh, met with in tetanus, is dependent upon irritation of this nerve. In his treatise upon nervous ' Varicose veins are most common on the inner side of the leg. The pain of these tumors may often be arrested by simple elevation of the foot, since the excess of blood in the part is thus relieved. ' It is claimed by Hilton that this nerve is distributed chiefly to the ligamentum teres, and that this accounts for it being so frequently affected by disease of the hip joint. PARALYSIS OF ANTERIOR CRURAL NERVE. 449 diseases, Eulenberg reports a case of clonic spasm localized in the quadri- ceps extensor muscle whicli was in- duced whenever an attempt to walk I or stand was made, but such cases are pf rare occurrence. I Paralysis confined to the anterior pural nerve is not of common occur- rence, but is still observed as a result of injuries to the vertebral column and pelvis, from tumors and extravasa- tions of blood in the region of the Cauda equina, and as a sequel to a severe type of inflammation of the knee Joint. It has been known to oc- cur in connection with psoas abscess and simple inflammation of the psoas muscle ; while fractures of the thigh, cuts, stab wounds, neuritis, pelvic tu- mors, and tumors of the thigh, have been reported as inducing this type of paralysis. Finally, it is a frequent symptom of spinal paralysis in all of its forms, and, more rarely, of cere- bral paralysis and of progressive mus- cular atrophy. From what has been already said as to the distribution of this nerve to muscles, it is easy to understand that the symptoms of this type of paralysis will be confined to the inability of the anterior thigh muscles to perform their accustomed functions. Such pa- tients can not flex the leg at the hip joint or raise the body from the re- cumbent position ; neither are they able to extend it nor to move the leg Fig. 166. — Cutaneous verves of the antei'ior part of the tldgh. (Sappey.) 1, external cutaneous branch of the lumbar plexus ; 2, 2, external cutaneous or su- perior perforating branch of the anterior crural nerve ; 3, 3, middle cutaneous or inferior perforating branch of this nerve; 4, filament furnished by this branch to the scrotum ; 5, internal cutaneous branch of the anterior crural nerve ; G, superficial division of this branch ; V, deep division of the same ; 8, superficial di- vision of the small musculo- cutaneous branch of the an- terior crural ; 9, transverse or patellar branch of the internal saphenous nerve ; 10, internal, vertical, or tib- ial branch of the same. 450 THE SPINAL NERVES. and foot forward when sitting. For this reason standing and walking are rendered very insecure, and such acts as running, jumping, etc., are often impossible with patients so afflicted. The regions of the skin which are supplied by the anterior cru- ral nerve may manifest disturbances of sensibility. If the scro- tum, labium, hypogastrium, or inguinal regions exhibit the same disturbances of sensibility, the seat of the paralysis is positively indicated as being above the origin of the branches of the two upper lumbar nerves (ilio-hypogastric, ilio-ingui- nal, genito-crural, and external cutaneous nerves). Among the evidences of disturbed sensibility which you may be called upon to recognize may be mentioned the conditions of anaes- thesia, hypersesthesia, the sensations of furriness, numbness, and chilliness. Atrophy of the muscles supjjlied by the anterior crural nerve may follow such paralysis. This is generally so well defined as to be apparent to the naked eye when the two thighs are compared ; but it may, occasionally, be so slight as to require careful measurement of the thighs. In some cases, certain muscles exhibit this atrophy more than others of the group, and even parts of muscles may appear flaccid, relaxed, and shrunken, while others preserve their normal appearance. Crural neuralgia may be manifested by paroxysms of pain upon the anterior and inner surfaces of the thigh and leg. It may affect the inner border of the dorsal surface of the foot and large toe. It is less frequent than neuralgia ol the sciatic nerve, which affects the back of the leg and plantar region of the foot. This diseased condition may result from compression of the lumbar plexus, from degeneration of neigh- boring lymphatic glands, exudations upon or in the substance of the psoas muscle, aneurism of the iliac arteries, strangu- lated hernia of the femoral region, dislocations at the hip joint, traumatism, exposure to cold or dampness, coxalgia, etc. The diagnostic points of tenderness are detected as fol- lows : 1, a crural point, at the exit of the nerve below Pou- part's ligament ; 2, an anterior femoral imint^ at the place of exit of the saphenous nerve through the fascia lata ; 3, an CUTANEOUS NERVES OF LOWER EXTREMITY. 451 % 15 16 19 \ 17 \ 20 21 i I zz 23, 2^ 25 . 1 OY. — A diagram of the cutaneous supply of the posterior aspect of the Icwer extremities. region supplied by the lateral branches of the intercostal nerves ; 1 6, region supplied by the posterior branches of the lumbar nerves; 17, region supplied by the iliac branch of the iliohypogastric nerve; 18, region supplied by the pudic nerve; 19, region supplied by the inferior gluteal branch of the small sciatic nerve ; 20, region supplied by the external cutaneous nerve ; 21, region supplied by the internal cuta- neous branch of the anterior crural nerve ; 22, region supplied by the small and great sciatic nerves ; 2^, region supplied by branches from the external popliteal nerve ; 24, region supplied by the external saphenous nerve ; 25, region supplied by the posterior tibial nerve. 452 TEE SPINAL NERVES, articular point, at the inner side of the knee joint, where the nerve divides ; 4, a plantar pointy on the inner side of the foot ; and, finally, 5, a digital p>oint^ over the tuberosity of the big toe. Spasm of the muscles of the hip, supplied by the anterior crural nerve (the spasmodic contracture of Stromeyer), may occur from any of the causes of crural paralysis previously mentioned. The thigh is then flexed, the pelvis raised up on the affected side, and the limb shortened and made rigid. THE OBTURATOR NERVE. This nerve arises mainly from the third and fourth lumbar nerves, but it often receives a fasciculus from the second. It descends in the innermost fibers of the psoas muscle, as far as the level of the brim of the pelvis, when it escapes from the inner border of that muscle, crosses the sacro-iliac articula- tion, accompanies the obturator vessels along the outer wall of the pelvis lying slightly above them, and passes into the thigh through the upper part of the obturator foramen. The table,' previously referred to, will enable you to grasp the details of the subdivisions of this nerve, and the distribu- tion of each branch ; but it fails to point out some important facts pertaining to this nerve, which help to explain its physi- ological attributes and to elucidate its clinical bearings. In the first place, we can see by this table that the obtu- rator nerve sends filaments to the hip joint and the knee joint. To the former articulation two filaments of this nerve can be traced, one given off to the capsular ligament, as the nerve passes through the obturator foramen, the other given off to the ligament um teres in the region of the notch in the acetabulum ; while, in the case of the knee joint, the obturator nerve sends filaments which enter that articulation at its pos- terior part, and which are probably intimately associated with its internal structures. The close relation which this nerve bears to the sacro-iliac articulation renders it probable ' Sec page 438 of this volume. THE OBTURATOR NERVE. 453 that some small filaments from the obturator nerve could be traced to this joint, although anatomical authors do not men- tion this fact as proven. In relation to this point, I quote from Fig. 1G8. — The muscular branches of the anterior and internal portions of the thigh. (Sappey.) 1, anterior crural nerve ; 2, branch which it furnishes to the iliacus muscle ; 3, twig which it sends to the internal portion of the psoas muscle : 4, middle cutaneous branch of the anterior crural, whose three branches have been divided close to their origin in order to show the branches to the quadriceps extensor and the internal saphenous nerve, which are more deeply placed ; 5 and 6, muscular filaments of the internal cutaneous nerve ; 7, origin of the cutaneous branches which pierce the fascia lata at the level of the saphenous opening ; 8, deep or anastomotic filament of the internal cutaneous branch of the anterior crural ; 9, branches to the rectus muscle ; 10, branches to the vastus externus ; 11, branches to the vastus internus; 12, 12, inter- nal saphenous nerve; 13, patellar branch of this nerve; 14, its vertical or tibial branch ; 15, obturator nerve ; 16, branch which it furnishes to the adductor longus ; 17, branch to the adductor brevis; 18, branch to the gracilis ; 19, branch to the ad- ductor magnus ; 20, lumbo-sacral trunk ; 21, junction of this nerve with the first sacral nerve ; 22, 22, lumbar and sacral portions of the sympathetic ; 23, external cutaneous nerve. 31 454 THE SPIXAL NERVES. the most excellent inonograx)li of Hilton' as follows : ^'I am disposed to think it sends some filaments to that articulation, or, at any rate, it lies close to it and would be likely to suffer from its proximity to it when diseased." Now, this distribu- tion to the internal portions of two joints, and possibly to a third, is the best possible explanation of the fact that the ob- turator nerve is the most frequent source of transmission of sympathetic pains, in case the hip joint be the seat of the disease, since the situation of its filaments causes it to per- ceive the first inflammatory changes within the hip ; and the effects of this irritation are naturally manifested in its termi- nal filaments — in the knee joint and the skin upon the inner side of that articulation. When we consider the course of the obturator nerve more in detail, w^e will perceive tlxnXpain in the region of the Jcnee may be due to other causes than morbus coxarius. It may be the external evidence of disease of the third or fourth lum- bar vertebrse, of disease of the sacro-iliac articulation, of a psoas abscess pressing upon it, and, if the pain be confined to the left side, a distention of the sigmoid flexure of the colon by faeces, or a malignant tumor of that portion of the colon or of the rectum might create pain in this region. It is well, therefore, when a patient suffering from a pain localized upon the inner aspect of the knee joint is brought to you, to care- fully examine all the different portions of the course of Ww obturator, anterior crural, and sciatic nerves before you de- cide as to the exciting cause of the pain, remembering always that pain can be perceived through no other structures than the nerves which are distributed to the region where the pain is felt, and that, by following the course of the nerve suffer- ing from irritation, the seat of the disease to which the pain is due may be confidently sought for. The distribution of the obturator nerve affords us somr lessons as to the physiological groupings of the muscles w^hich act upon the thigh and leg. It first supplies the obturator extemus, and then the adductor brevis, the adductor longus. 1 Op, cit. » DISTRIBUTION OF THE OBTURATOR NERVE. 455 the adductor magnus, and the gracilis. In some cases the pectineus is supplied by this nerve or the accessory obturator nerve, but its chief source of supply is undoubtedly from the anterior crural. This fact would seem to indicate that the gracilis muscle, whose supply from the obturator nerve is very constant, should be classed as an adductor muscle, rather than as a flexor, and that this is its true action seems well proven on mechanical principles. Its point of insertion is just below the central point of the limb which it moves, hence, it seizes the limb just beyond the central point, between the fulcrum (the hip joint) and the resistance, and is thus able to greatly assist the adductor muscles. The obturator nerve is thus, physiologically considered, the adductor nerve of the lower extremity, while the muscles which it supplies also act as external rotators of the thigh, on account of the obliquity of their fibers. That the pectineus muscle acts as a flexor as well as an adductor is proven by its nerve supply, as well as by the direction of its fibers and its points of origin and in- sertion, since it receives filaments both from the anterior cru- ral and obturator. CLINICAL P0I:N^TS PERTAINIls^G TO THE OBTURATOR NERVE. . The diagnostic value of pain in the region of the knee joint as an evidence of disease in other localities, to which the obturator nerve is either distributed or with which it bears some intimate relations, has been discussed already at some length.' Such a pain may be dependent, however, also upon lesions interfering with the free action of the anterior crural and sciatic nerves, and, for that reason, the course of these three nerves should always be carefully examined be- fore a positive diagnosis can be made as to the exciting cause of pain in the region of the knee. The obturator nerve is even less frequently affected with isolated paralysis than the anterior crural, but, if so, it may be referable to the same list of causes. In addition to the causes mentioned, may be added, however, compression of the ^ See page 448 of this volume. 456 THE SPmAL NERVES, obturator nerve from a strangulated hernia through the obtu- rator foramen, the pressure exerted by the head of a foetus during its passage through the pelvis, and the use of forceps during difficult labors. From what has been said as to the supply of muscles by this nerve, it is apparent that a patient afflicted with obtu- rator paralysis can not adduct the thigh, or perform the acts of pressing the knees tightly together or of crossing the affected leg over the other. Since the adductor muscles assist in the external rotation of the thigh, this movement is im- paired, especially in the sitting posture, when the external rotators attached to the great trochanter are rendered inert. The affected leg soon becomes fatigued in walking, and riding upon horseback is difficult, since the knees can not grasp the saddle. Some disturbances of sensibility may be detected in the regions of the sldn supplied by this nerve ; these will be the same in character as those mentioned as existing in crural paralysis. * THE ACCESSORY OBTURATOR NERVE. This nerve is sometimes wanting. When it is present, its origin is extremely variable. It may arise from the third and fourth lumbar nerves ; from the fourth lumbar and obturator nerves ; or by separate filaments derived from the second, third, and fourth lumbar nerves. It descends along the inner side of the psoas muscle, crosses in front of the pubes, passes behind the pectineus muscle, and there divides into branches to the pectineus and the hip joint. It usually gives off a large branch of communication to the obturator nerve (which is often larger than the continuation of the accessory nerve it- self), and terminates as a cutaneous nerve to the thigh and leg. The frequent absence of this nerve deprives it of any clin- ical importance, as it is impossible in any one case to decide if pain in the regions supplied by the obturator nerve is partly due to the accessory obturator or not, while the variations in * Sec page 450 of this volume. THE SACRAL NERVES. 457 the method of origin of the nerve renders it impossible to definitely decide as to the seat of irritation, provided the pain could be traced to the accessory nerve and localized above the pelvis. THE SACRAL NERVES. We now have reached, in the natural progress of this course of lectures, the terminal nerves of the spinal cord. As was the case with those of the lumbar region, the sacral nerves divide into anterior and posterior divisions, but they differ from the lumbar nerves in the fact that these ante- rior and posterior divisions escape from separate foramina in the sacrum, while, in the portions of the cord above the sacral region, the spinal nerves divide after their escape from the inter-vertebral foramina. These nerves form, by their anterior divisions and the addition of the lumbo-sacral cord, the sacral plexus ; while their posterior divisions are distributed to the muscles of the lower lumbar region and to the integument of the gluteal, sacral, and coccygeal re- gions. The sacral plexus is triangular in shape, and is formed by the lumbo-sacral cord, the three upper sacral nerves (their anterior divisions), and a portion of the fourth sa- cral nerve. Its constituent fibers converge to form one flat- tened cord, which leaves the pelvis through the lower part of the great sacro-sciatic foramen, below the pyriformis muscle, while, within the pelvis, the plexus lies upon the pyriformis muscle, and is covered by the pelvic fascia and the two terminal branches of the anterior division of the internal iliac artery (the sciatic and pudic). The branches which are given off by this plexus are arranged, in the table which I now show you, in such a way as to- make them apparent to the eye, while the distribution of each is shoAvn in the next table in detail. The first table is not intended to exhibit alone the branches of the sacral plexus, but rather to give the general arrangement of the 458 THE SPINAL NERVES. sacral nerves in their entirety. You will perceive that the arrangement of both the anterior and posterior divis- ions is considered, and that the component parts of the sacral plexus, as well as its main subdivisions, are clearly set forth. NERVES OF THE SACRAL REGION.' SACRAL NERVES. ' Posterior divisions. External branches. Anterior divisions. ' Form anastomotic loops on the back part of the sacrum and on the posterior aspect of the great sacro-sciatic ligament, Terminate in cutaneous branches in the gluteal region. [ Are distributed to the multifidus spinas Internal J muscle, branches. 1 The back part of the coccyx is supplied by [ the two lower nerves. f LUMBO-SACRAL CORD. 1st sacral nerve. 2d sacral nerve. OD SACRAL nerve. Part of 4th sa- cral nerve. .SACRAL . r PLEXUS. ^ J (1) Superior gluteal nerve, (2) Muscular branches, (3) Small sciatic nerve, (4) Great sciatic nerve, (5) PuDic nerve, [ (6) Articular. Each of the five branches of the sacral plexus, as well as those included in the muscular group, to which no special names are given, will now be separately described. I have endeavored to embrace in this second table all the points pertaining to the purely anatomical distribution of each of these nerves, but much of interest, from a clinical as- pect, still remains in relation to some of them, which can not be shown in a tabular form. This table will, however, prove of assistance to you in reviewing the distribution of the nerve which is, at any time, under discussion, and, fur- thermore, avoid lengthy descriptions of a purely anatomical character. ' Taken from the "Essentials of Anatomy" (Darling and Ranney). G. P. Putnam's Sons, New York, 1880. THE SUPERIOR GLUTEAL NERVE. 459 DISTRIBUTION OF THE BRAI^CHES OF THE SACRAL PLEXUS. SACRAL PLEXUS. SCPERIOR GLUTEAL. JfuSCULAR branches. Articular branches. Small SCIATIC \ Superior hv^xidx. \ Gluteus medius muscle ^ { (jtluteus minimus muscle. \ I Gluteus medius muscle, Inferior branch. 4 Gluteus minhnus muscle, ( Tensor vaginae femoris. ' Pyriformis, Obturator internus, Gemellus superior, Gemellus inferior, Quadratus femoris. To hip joint. [ Lifer i or cjluteal i branch. dal branch. Cutaneous branch. Articular (to the hip joint). Gluteus maximus muscle, / Integument of the side of the penis or vidva. { Integximent of perinaeum, ?- J Integument of upper and inner part of the I thigh, y Integument of scrotum or labium. \ Integument over the gluteus { maximus muscle, i Integument of the inner and -| outer sides of posterior ( aspect of the thigh. Ascending. Descending. Great SCIATIC ■{ Muscular NERVE. Terminal . PuDir; NERVE. Adductor magnus, " Semi-membranosus, Semi-tendinosus, Biceps flexor cruris. External popliteal nerve, Lvternal popliteal nerve. Cutaneous or ( Integument of anal region, superficial -j scrotum, penis, and labia, perineal. { Sphincter ani muscle. ^ruscular . . ■{ Muscles of the perinaeum. I Inferior hemorrhoidal. I Dorsal nerve of j Integument of the dorsum of the penis, (^ penis. I Branch to corpora cavernosa of the penis. Perineal THE SUPERIOR GLUTEAL NERVE. This nerve arises from the back part of the lumbo-sacral cord, and, while generally included as a branch of the sacral plexus, can not be, therefore, properly regarded as a nerve of sacral origin. It escapes from the pelvis through the upper part of the great sacro- sciatic foramen, in company with the gluteal vessels, lying above the pyriformis muscle. It divides into a superior and an inferior branch, as is shown in the table ' to which I have called your special attention, the for- mer of which accompanies the superior gluteal artery between ' Modified from a table taken from " The Essentials of Anatomy " (Darling and Ran- ney). G. P. Putnam's Son^ New York, 1881. ^ See page 459 of this volume. 460 TEE SPIXAL NERVES. the gluteus medius and minimus muscles, while the latter passes between the same muscles, but lower than its fellow. The distribution of this nerve to the gluteus medius, gluteus minimus, and tensor vaginae femoris muscles, stamps it as the one which presides chiefly over the act of internal rotation of tJie thigh, since these three muscles are the only ones which can perform this limited movement of the femur. Its cutaneous distribution again confirms the axioms of Hil- ton ; ' since the skin over these muscles is thus supplied, while some filaments running over the fascia lata, to which the tensor vaginse femoris is attached, can be demonstrated. CLINICAL POINTS PERTAINING TO THE SUPERIOR GLUTEAL NERVE. The cutaneous covering of the gluteus medius and mini- mus muscles is not alone supplied by the gluteal nerve, as the lumbar nerves may be seen coursing along over the lower part of the abdomen, then passing over the crest of the ilium, and finally reaching this part of the thigh. While this might seem, at a first glance, to be a peculiar admixture of lumbar and sacral nerves, yet, on returning to a point just made, we discover that the superior gluteal nerve is of lumbar origin, although apparently a branch of the sacral plexus; hence, the skin, supplied by branches of lumbar origin, protects all those regions to which muscular branches derived from the same sources can be traced. We see the region of the gluteus maximus muscle apparently avoided' by the nerves which descend from the abdomen to supply the skin of the adjoin- ing region, and, when we seek for an explanation of the fact, Ave find that this muscle is supplied by the small sciatic nerve (derived from the sacral plexus, and having no connection with the lumbar nerves) ; hence, the integument covering that muscle could not be supplied by nerves whose source of origin would prevent a perfect sympathy between the skin and the muscular structures which it covers. The relation of this nerve to the gluteal artery, as it es- capes from the great sacro-sciatic foramen, gives it a surgical ' See page 359 of this volume. • Hilton, op cii. DISTRIBUTION OF SUPERIOR GLUTEAL NERVE. 461 importance, as that vessel is sometimes ligated for haemor- rhage from some of its branches. The three muscles supplied by the superior gluteal nerve, if acting in connection with the gluteus maximus muscle, be- come the abductors of the hip joint, while the posterior half of the gluteus medius and the posterior fifth of the gluteus minimus assist in extension of the thigh upon the trunk, since their origin lies on a plane posterior to their insertion into the trochanter. Thus we are enabled to class the superior gluteal nerve as a factor in three of the move- ments of the hip joint, viz., internal rotation, abduction, and extension. When the superior gluteal nerve is subjected to irritation, a spasmodic condition of the gluteal muscles may be pro- duced. It is extremely rare to have such a condition devel- oped in the glutei muscles alone, but one such case is reported by Remak. In this case the spasms of the legs consisted of a series of gluteal contractions which, when the patient would attempt to walk, would draw the leg backward and render it fixed in that position. We see, however, the glutei muscles frequently affected with spasm (in connection with muscles of the lower extremity supplied by other nerves) in tetanus, rheumatic inflammation of the hip joint, arthralgia, neural- gia, and lesions within the pelvis which aifect the sacral plexus. The gluteal muscles may be affected with paralysis, but it is rare that the paralysis is confined exclusively to that region. As a rule, these muscles become affected as the result of lesions which involve the sacral plexus to a greater or less extent, such as spinal diseases, tumors in the spinal canal or pelvis, lesions of the cauda equina, fractures of the sacrum, fractures of the pelvis, etc., so that the paralysis of the glutei muscles is masked by a similar condition of muscles supplied by other nerves. When the glutei muscles are paralyzed, in connection with the tensor vaginae femoris, the pyriformis, and the obturator internus, as is more frequently observed, the rotation of the thigh inward becomes impossible, and out- 462 THE SPmAL NERVES. ward rotation also becomes somewhat impaired, as the adduc- tor group and the psoas and iliacus have chiefly to perform it. Abduction of the thigh is rendered extremely difficult, and, if the paralysis be complete, absolutely impossible, while flex- ion of the thigh is impaired and limited in its extent. When such patients attempt to walk, the glutei muscles no longer preserve the relations of the trunk to the thighs, and a diffi- culty in preserving the balance is therefore present. This is especially noticeable when an attempt to ascend a flight of steps is made, as the trunk has then to be inclined forward. The affected muscles usually undergo atrophy when thus de- prived of their normal power, and the gluteal region loses its natural roundness and firmness. The disturbances of sensibility which may coexist with this type of paralysis will depend somewhat upon the seat of the exciting cause, as well as upon its character. Pain may be a means of making a diagnosis of the development of the ex- citing lesion before the paralysis is developed, if the precepts given you in the earlier lectures of this course be applied, ' remembering always that the cause of the pain must be sought for along the course of the cutaneous nerves which supply the region where pain is felt, and that the omission on your part of one of the nerves whose filaments are present in the region of pain may entail a complete failure in discovering the cause. THE MUSCULAR BRANCHES OF THE SACRAL PLEXUS. By reference to the table of the distribution of the vari- ous branches of the sacral plexus,' you will perceive that five muscles receive a direct supply from it through branches which are not specially named, being included in the muscular set — these five muscles being the pyriformis, obturator internus, gemellus superior, gemellus inferior, and quadratus femoris. If we consider the function of these five muscles, it will be ; evident that they should receive their nerve supply from the same source, provided the axiom of Hilton — that the nerve ' See page 359 of this volume. ' See page 459 of this volume. MUSCULAR BRANCHES OF THE SACRAL PLEXUS 463 distribution of muscles ' is a guide to their function — be true, as they all assist in the external rotation of the thigh by their action upon the great trochanter of the femur. The situation of these five muscles is such that a direct supply from the sacral plexus might almost be inferred. The pyri- formis and obturator internus muscles arise from within the pelvis and escape from its cavity by means of the greater and lesser sacro-sciatic foramina, while the two gemelli muscles and the quadratus femoris are attached to the OS innominatum in the immediate vicinity of these two foramina. Now, the sacral plexus lies upon the pyriformis muscle, and would naturally supply it, while the other four muscles bear such an intimate relation with the pyriformis, as it escapes from the pelvis, as to render a supply from the sacral plexus easy, while the similarity of function between the ^NQ muscles would presuppose a nerve supply from the same source. In the lectures upon the obturator and anterior crural nerves, the action of the adductor and flexor groups of mus- cles, in assisting the external rotation of the thigh, was dis- cussed, and we here come upon another group of muscles which also tend to perform the same movement of the lower limb. The questions may arise to your minds — how are we able to explain a dissimilarity in the sources of motor power in groups of muscles which have a common function to per- form % How are we able to reconcile the axioms of nerve supply, so often quoted, with this apparent contradiction ? The answer to both of these questions is settled by a careful scrutiny of the combined actions of each of these separate groups of muscles. In the first place, the five muscles of the thigh, supplied by the sacral plexus of nerves through its muscular branches, can not perform the movement of exter- nal rotation of the thigh when the subject is in the sitting posture. It is in this relative position of the thigh and trunk that the adductor group of muscles, aided by the psoas and iliacus, become important factors in the movement of external J Op. cit. 464 THE SPINAL NERVES, rotation ; and it is to be remembered that this movement is but a secondary function with these latter muscles, since they are designed chiefly to insure adduction and flexion of the thigh. Each muscle of a group is usually supplied by that nerve whose branches are also distributed to others of that group which aid in its primary action, rather than in any secondary movement in which it may chance to participate ; hence the psoas and iliacus derive their power from the ante- rior crural, the adductor muscles from the obturator, and the fiYQ muscles posterior to the hip joint from the sacral plexus, and thus the primary action of each group is indicated by the nervous supply, as well as by the points of origin and inser- tion of each muscle. THE SMALL SCIATIC NERVE. This branch of the sacral plexus is given off from its lower and posterior part, and escapes from the pelvis through the sacro-sciatic foramen, below the pyriformis muscle, in com- pany with the sciatic vessels. It descends beneath the gluteus maximus muscle, in which region it lies to the inner side of the great sciatic nerve, and continues beneath the fascia lata as low down as the popliteal space, where it perforates this fascia and joins with the external saphenous nerve, giving off also cutaneous branches of its own to the popliteal space and the back of the calf. The branches of this nerve, which are enumerated in the table,' comprise the inferior gluteal, the inferior pudendal, and the cutaneous filaments distributed over the gluteus max- imus muscle, and the regions previously mentioned. The fact that this nerve supplies the gluteus maximus muscle with motor power gives it an importance to the anatomist, since this muscle is one of the most important factors in regulating the position of the trunk and the lower extremity during all the various attitudes assumed by the living subject ; but there are also some suggestions of value which have been thrown out by previous authors upon anatomy which will ^ Sec page 459 of this volume. THE SMALL SCIATIC NERVE. 465 merit your closest attention, especially as they are omitted ill some of the descriptive text-books. Fig. 169. — The small sciatic ncrvc^ loith its branches of distribution and termination. (Sappey.) 1, superior gluteal nerve; 2, small sciatic nerve; 3, 3, 3, branches to the gluteus maximus ; 4, branch to the pyramidalis ; 5, internal pudendal branch of the small sciatic ; 6, femoro-poplitcal branch of the same nerve ; Y, 7, trunk of the great sci- atic ; 8, branch which it gives to the long head of the biceps ; 9, branch to the short head of the same muscle ; 10, 10, branch to the semi-tendinosus (the latter muscle has been divided and turned back, to show the semi-membranosus) ; 11, 11, branch to the semi-membranosus; 12, 12, another branch, rising from the common trunk with the preceding nerve, and passing under the semi-membranosus to be distributed to the adductor magnus ; 13, external popliteal nerve; 14, internal popliteal nerve ; 15, filament to the plantaris ; 16, 16, nerves to the gastrocnemius; IV, origin of the external saphenous nerve. In the first place, this nerve sends filaments to the peri- nseum and genitals ' of the male and female, after supplying ' In the female, the filaments probably go to the vulva and vagina ; but, in the male, the side of the penis is thus supplied. 4:QG THE SPINAL NERVES. the gluteus maximus muscle ; and the suggestion is made by Hilton, in reference to this point, that the action of this muscle in its relation to coitus may tend to explain the neces- sity for a sympathy between these two parts by means of a common nerve supply. Again, the recognition of the perineal branch of the small sciatic nerve is sometimes important in practice. If you care to trace this nerve upon the dead subject, you will find that it escapes from beneath the perineal border of the gluteus maximus muscle, runs along the outer portion of the peri- nseum, and, finally, sends cutaneous filaments to the sides of the penis. The perineal region is also sujiplied by the peri- neal branches of the pudic nerve, which escape, posteriorly to those of the sciatic, from beneath the same muscle. !N'ow, either of these two nerves may be the cause of a pain referred to the perinseum and the penis, and their points of escape from beneath the gluteus maximus muscle are so placed as to render them frequently subjected to pressure from sitting upon hard or uneven seats. It is thus possible for pains, referred to the penis, to be wrongly attributed to diseases of the bladder, calculus in the bladder, urethral troubles, and all other types of disease which are commonly indicated by more or less pain in that locality, when the cause may be found and correctly diagnosed by following up the course of the perineal branch of the small sciatic. Such a case is reported by Hilton, where prominent surgeons of Europe, among them Mr. Key, had diligently and unsuccessfully searched for the cause of a pain, referred to the penis, along the course of the pudic nerve, and where the patient had been treated for disease of the bladder, a careful examination subsequently revealing the true cause to be a spot of hardened tissue pressing upon the peiineal branch of the small sciatic nerve, which was cured (as well as the pain which it created) by the application of nitric acid over the seat of thickening. It is, therefore, well to remember the course of this branch, as well as those of the pudic nerve, when investigating for the cause of pain in the penis or perinjeum. THE PUDIG NERVE. 467 THE PUDIC KERVE. This brancli of the sacral plexus arises from its lower part, and immediately escapes from the pelvis by means of the great sacro-sciatic foramen in company with the pudic artery, the sciatic vessels and nerves, and the gluteal vessels and nerves. The situation of the nerve in this foramen is on the inner side of the great sciatic nerve, both of which escape through the lower part of the foramen, beneath the pyri- formis muscle. The pudic nerve then reenters the pelvis through the lesser sacro-sciatic foramen, in company with its artery, and immediately gives off its inferior hemorrhoidal branch. From this point the nerve passes along the outer wall of the ischio-rectal fossa, lying above the pudic artery (both artery and nerve being covered by the obturator fas- cia), and divides into the perineal branch and the dorsal nerve of the penis. Of these three branches of the pudic nerve, the distribu- tion has been given in a previous table, but with less detail than the subject, perhaps, demands. The inferior hemorrhoidal nerve occasionally arises di- rectly from the sacral plexus rather than as a branch of the pudic ; its course runs along the ischio-rectal fossa, and it is distributed to the sphincter muscles of the rectum and the skin around the region of the anus. It communicates freely in this region with the superficial perineal and inferior pu- dendal nerves. The perineal nerve is the largest branch of the pudic, and accompanies the superficial perineal artery. It divides into two sets of terminal filaments — the cutaneous or superficial perineal nerves and muscular branches. The former of these give a few twigs to the sphincter ani and levator ani muscles, but are chiefly distributed to the integument of the perinseum, scrotum, labium, and the penis, communicating freely, in the region of the anus, with the inferior hemorrhoidal nerve. The muscular branches usually arise from the pudic nerve by a common trunk, which passes forward and inward un- 468 THE SPINAL NERVES. derneath the transverse perinei muscle ; its terminal fila- ments are given off to the transverse perinei, erector penis, accelerator urinse, and compressor urethrse muscles, and a twig is often sent to the bulb of the urethra. The dorsal nerve of the penis is the smaller terminal fila- ment of the pudic nerve, which accompanies the pudic artery along the rami of the pubes and ischium, between the layers of the deep perineal fascia ; it then pierces the suspensory lig- ament of the penis and continues its way along the dorsum of that organ as far as the glans penis. It gives a branch to the corpus cavernosum, and supplies the integument of the dor- sum ^ of the penis ; in the female the course of the nerve is about the same, although the size of the nerve is smaller, since the clitoris is minute in its size as comj)ared with the organ of the male. CLINICAL POINTS PERTAINING TO THE PUDIC NERVE. A careful study of the distribution of the various branches of this nerve will show that it is the source of motion to the muscles of the perinseum and urethra, and of sensation to the integuinent of the perinseum, scrotum, labium, penis, and the mucous covering of the clitoris, as well as that lining the urethral canal. The friction made upon the cutaneous nerves of the external genital organs in the acts of sexual intercourse and masturbation creates a reflex act within the spinal cord, which creates the turgidity of the penis and clitoris during the first portion of those acts ; and, later on, a series of muscular contractions in the perineal muscles and the involuntary mus- cular fiber of the urethral canal are produced, which assist in the expulsion of semen, in the male, and the secretion of the glands of Bartholine in the female. That this is the true explanation of emission is evidenced by the fact that onan- ' Hilton Btatcs that tlic integument of the sides of the penis is supplied by the perineal bmnch oi the iji/cvior ffhtieed nerve, and from no other source. This statement differs from most of the standard authors, but it seems to be supported by clinical demonstra- tion. The reader is referred to page 466 of this volume, where the subject is discussed from its physiological and clinical point of view.' THE GREAT SCIATIC NERVE. 469 ism is most effectually prevented by blistering the cutaneous covering of the penis and the mucous covering of the clitoris. In some cases of fracture of the spine, in the dorsal region, where a part of the spinal marrow is left intact below the seat of fracture, you may be able, by repeatedly pinching the skin of the scrotum and penis, to produce spasmodic contractions of the muscles of the perinseum and urethra, and often to ect a turgidity of the genital organ to such a degree as to make it resemble an imperfect erection or priapism. The ejaculation of the last few drops of urine from the urethra is unquestionably effected by a reflex act through the sensory and motor fibers of the pudic nerve, in consequence of the irritation produced in the sensory fibers of the urethral mucous membrane from pressure of the urine or the contact of its saline ingredients. It is not uncommon for rectal disease to produce sympa- thetic manifestations in the genito-urinary organs, in the form of neuralgic pains, involuntary emissions, incontinence of urine, etc.; such effects can only be explained by the dis- tribution of the pudic nerve to the integument about the anus (and, I believe, to the walls of the rectum also), which allows reflex motor impulses to be sent from the spinal cord, in response to rectal irritation, to the genito-urinary organs and perineal muscles. THE SCIATIC NERVE. This nerve arises from the lumbo-sacral cord and the four upper sacral nerves, and is a direct continuation of the sacral plexus. It escapes from the pelvis through the great sacro- sciatic foramen below the pyriformis muscle, lying on the outer side of the pudic vessels and nerve. It then passes downward between the trochanter major of the femur and the tuberosity of the ischium, lying behind the external rotator muscles of the hip joint and the adductor magnus, to the lower third of the back of the thigh, where it divides into its two terminal branches, the external and internal popliteal nerves. 32 I 470 THE SPINAL NERVES. In the lower two thirds of its course, it is covered by the ' lower fibers of the gluteus maxim us and biceps muscles. It - Fig. 170. — The great sciatic nerve, with its branches of distribution and termination. (Sappey.) 1, superior gluteal nerve; 2, small sciatic nerve; 8, 3, 3, branches to the gluteus niaximus ; 4, branch to the pyramidalis ; 5, internal pudendal branch of the small sciatic ; 6, femoro-popliteal branch of the same nerve ; 1, 7, trunk of the great sci- atic ; 8, branch which it gives to the long head of the biceps ; 9, branch to the short head of the same muscle ; 10, 10, branch to the semi-tcndinosus (the latter muscle has been divided and turned back, to show the semi-membranosus) ; 11, 11, branch to the semi-membranosus; 12, 12, another branch, rising from the common trunk with the preceding nerve, and passing under the semi-membranosus to be distributed to the adductor magnus ; 13, external popliteal nerve; 14, internal popliteal nerve; 15, filament to the plantaris ; 16, 16, nerves to the gastrocnemius; 17, origin of the external saphenous nerve. gives off branches to the hamstring muscles and the adductor magnus, and some articular branches to the back of the hip joint. The two tables which I now show you are designed to DISTRIBUTION OF THE SCIATIC NERVE. 471 illustrate the branches given off by the external and internal popliteal nerves. The former of these is the smaller of the two, and passes along the outer side of the popliteal space close to the biceps muscle, while the other traverses the middle of the popliteal space as far as the lower border of the popliteus Lscle, where it becomes the posterior tibial nerve. Fig. 171. — TJie external popliteal nerve. (Sappey.) I, external popliteal nerve ; 2, peroneal or cutaneous branch ; 3, communicaus peronei ; 4, external saphenous nerve ; 5, trunk formed by the junction of the external saphe- nous with the commuuicans peronei ; 6, calcanean branch rising from the trunk ; 7, external terminal branch of the trunk on its way to form the external doisil branch of distribution to the fifth toe ; 8, its internal terminal branch which forms the internal dorsal branch for the fifth toe and the external dorsal branch for the fourth toe; 9, 9, musculo-cutaneous nerve; 10, 10, its terminal branches; 11, anas- tomosis of its external terminal branch with the external saphenous ; 12, anastomosis of its internal and external terminal branches with each other; 13, anterior tibial nerve; 14, terminal portion of this nerve, anastomosing with the musculo-cutaneous, and dividing to form the deep branches of distribution on the dorsum of the foot to the internal side of the great toe and the external side of the second toe. 472 TEE SPINAL NERVES. KERVES OF THE LEG AND FOOT. EXTERXAL POPLITEAL NERVE. (Peroneal NERVE.) Articular branches. Cutaneous branches. Anterior Tibial Nerve. (4) MUSCULO-CUTANEOUS Neuve. INTERNAL POPLITEAL NERVE. Articular . Muscular . External Saphe- nous Nerve. Three in number, Distributed to knee joint. j; Two or three in number, •] Supply integument of outer and back part of ( the leg. r Muscular (to muscles in front part of Ice; 1 and to the peroneus tertius). External j Extensor brevis digitorum, branch. \ Articulations of the tarsus. Internal j /^i^f^fwwm/ of the adjoining side- ^ branch. ( of the great and 2d toes. ( T,r 1 \ Peroneus loncus, Muscular, -j ^^^.^^^^^ brevis. ( Intec/ument of outer side of foot Extei-nal] and ankle, branch. ] Integument of the adjoining sidc- (^ of od, 4th, and 5th toes, r Integument of the inner side of J. , I the foot and ankle, InternaC ^ jntcgument oi the Sidiommu sidv branch. . ^j. ^^ ^^^^ gj ^^^g ^^^^ j,^j^^.^. (4) Posterior Tihial Nerve. side of great toe. Three in number. Distributed to knee joint. Gastrocnemius, Plantaris, Soleus, Popliteus. Formed by two filaments, one from each of the popliteal nerves. Integument of the outer side of foot and the little tee. ! Flexor longus pollicis. Flexor longus digitorum, Tibialis posticus. Plantar \ Integummt of heel and inner pan cutaneous. | of sole of foot. fxx. .. 1 ( Intequmeni of the ^'f *^^ u \ 4 toes on inner branches. . ] ^.^^ ^^ ^^^^^ Flexor brevis digi- torum, Abductor pollicis, -{ Flexor brevis pol- licis. Two inner lumbri- calcs muscles. Articular (to tarsus), Cutaneous (to sole of foot). ' Flexor accessor! r , Abductor minii I digiti. U outer toes, Flexor brevis mini- mi digiti. 4th interosscd muscle. 'yd and 4th h,: bricalos. Deep J Rest of interos? branch. I Adductor poUiti 1^ [Transversus pcil Internal PLANTAR. External PLANTAR. Muscular Muscular Supei'fcial branch. TEE NERVES OF THE LEG. 473 If yon will study these tables, you will perceive that the external popliteal nerve distributes articular branches to the Fig. 172. — T7ie internal popliteal nerve. (Sappey.) 1, trunk of the great sciatic ; 2, external popliteal ; 3, internal popliteal ; 4, 4, branches to the gastrocnemius^ — both nerves and muscle have been divided ; 5, origin of the external saphenous ; 6, branch to the solcus, divided together with the muscle ; 7, internal popliteal nerve passing through a fibrous ring in the soleus ; 8, 8, branch springing from the lower portion of this nerve, and likewise passing through the fibrous ring of the soleus. At this level it gives off a reflected or ascending division, which penetrates the popliteus at its deep surface, but is not seen in the cut, and a more slender descending division which makes its way through the interosseus mem- brane and supplies the tibialis auticus muscle ; 9, 9, posterior tibial nerve ; 10, 10, branches which it furnishes to the flexor longus digitorum ; 11, 11, branches which it gives off to the tibialis posticus muscle ; 12, 12, branches to the flexor longus pol- licis ; 13, calcanean branches ; 14, terminal extremity of the external saphenous nerve. knee joint, and cutaneous filaments to the outer and back part of the leg. The two main nerve trunks which arise from 4Y4 THE SPINAL NERVES. it are called the anterior tibial and the musculo-cutaneons, both of which are given off from the main trunk after it pierces the peroneus longus muscle about one inch below the head of the fibula, although three articular and several cuta- neous filaments also arise from it. You will also perceive that four main branches are given off from the internal pop- liteal nerve, viz., articular and muscular branches, and the ex- ternal saphenous and posterior tibial nerves. The muscular filaments supply four muscles in the immediate vicinity of the knee, while the articular filaments, as in the preceding nerve, are distributed to the knee joint. Other points of interest might be specially designated as comprised in these pages, but they will be considered in their practical relations when the clinical points which are presented by the nerves of the lower extremity are considered. I desire to call your attention, first, to the fascia of the leg, into which three muscles of the thigh are inserted, viz., the sartorius, the gracilis, and the semi-tendinosus. I have already called your attention to the fact that the fas- ciae of the body are always to be regarded as one of the points of insertion of the muscles which are attached to them ; now, if this be true, and it undoubtedly is so, we ought to discover a particular distribution of the cutaneous nerves at this point, since the nerves which supply the mus- cles supply also the skin over the insertion of the same mus- cles. We shall find, on dissection of this region, that the long saphenous, the obturator, and a branch of the sciatic nerves are distributed in the skin of the calf ; the one de- rived from the anterior crural (which supplies the sartorius), another a filament of the obturator (which supplies the gra- cilis), and the third derived from the sciatic (since it supplies the semi-tendinosus muscle). These three nerves, therefore, supply both the fascia of the leg and the skin on the inner side of the leg below the knee joint ; hence, pain in this re- gion must be sought for along the course of one of these three nerves. It is too common among physicians to regard a pain which is localized at the inner side of the knee as dependent THE NERVES OF THE LEG. 475 upon the obturator nerve, to the exclusion of the sciatic or the anterior crural ; but anatomy clearly teaches us that Fig. 1Y3. — The external saphenous nerve audits accessory^ the communicans peronei. (Sappey.) 1, internal popliteal nerve ; 2, nerve to the external head of the gastrocnemius ; 3, nerve to the internal head ; 4, external saphenous nerve ; 5, external popliteal nerve ; 6, communicans peronei ; 7, peroneal or cutaneous branch ; 8, branch sometimes given off by the external saphenous to the fourth and fifth toe ; 9, trunk formed by the junction of the communicans peronei with the external saphenous ; 10, calcanean branch given off by this trunk ; 11, plantar cutaneous branch of the posterior tibial; 12, internal saphenous nerve ; 13, 13, 13, posterior branches of this nerve. there are three possible lines of direction, which we are bound to explore in searching for the situation of the real cause which is producing it. We should always carefully examine all the anatomical relations of the obturator, the sciatic, and the anterior crural nerves, in order to ascertain, if possible, the real cause of pain which is expressed on the in- 476 THE SPINAL NERVES. ner side of the knee joint, and the axiom of nerve distribu- tion, which was first pointed out by Hilton, and to which I have frequently directed your attention, offers us, in this instance, as in many others, a simple rule which should guide us in searching for the cause of pain before we attempt measures for its relief. Fig. 1*74. — The plantar nerves, their course, anastomoses, and distribution. (Sappcj.) 1, internal plantai' nerve ; 2, 2, branches which it gives to the abductor pollieis ; 3, branch which it gives to the accessorius ; 4, branch to the flexor brevis digitoruni ; 5, branch of distribution to the internal plantar surface of the great toe ; 6, another branch of the internal plantar dividing into three secondary portions, which subdivide, in their turn, to form the branches of distiibution on the plantar surface to the outer side of the groat toe, both sides of the second and third toes, and the inner side of the fourth toe ; 7, external plantar nerve ; 8, 8, branches which it sends off to the abductor minimi digiti ; 9, branch to the accessorius; 10, branch of distribution on the plantar surface to the outer side of the little toe; 11, another branch of the same nerve dividing to supply the inner side of the little toe and the outer side of the fourth toe ; 12, anastomosis of the internal with the external plantar ; 13, origin cf the deep branch of the external plantar. I have found, in several instances, that local ansesthetics, when applied to the skin over the seat of pain, frequently have the power of relieving a sense of distress in other re- gions apparently far removed from it, but still connected with the seat of pain by means of a nervous communication. Thus, in disease of the hip joint, an anodyne applied in the CLINICAL POLNTS AFFOBDED BY NERVES OF LEG. 477 region of the knee joint will often relieve symptoms whicli are referable to the hip, and we can only attribute this effect to a benumbing influence exerted by means of the sciatic and obturator nerves upon that joint, since both of these nerves send articular filaments to it, as well as cutaneous filaments to the region of the knee. In some instances, where abnormalities of origin of nerve filaments can be detected, I believe that, if you will trace the nerve upward for some distance toward the spinal marrow, you will find that the cutaneous filaments of the nerve, which apparently has an abnormal origin, are in intimate communi Fig. iTo, — T.'ie deep branch of the external plantar (Sappcy.) 1, internal plantar nerve ; 2, its internal branch ; 3, its external branch, whose two divis- ions have been cut, together with the adductor pollicis, to show the deep branch of the external plantar; 4, trunk of the external plantar; 5, its superficial branch, which divides almost immediately into two secondary branches, distributed to the fourth and fifth toes ; 6, its deep "branch, distributed to the adductor poUicis, trans- vcrsus pedis, and the intcrossei ; 7, branches to the adductor pollicis ; 8, 8, branches to the interossei ; 9, branches to the transvcrsus pedis, cation with the nerve trunk whose functions are assisted by them, and from which its most frequent origin can be verified. If we examine the anatomy of the hip joint, we shall find 478 THE SPINAL NERVES. that a branch of the anterior crural nerve passes in close rela- tion with its capsule, if it is not intimately associated with it ; that a branch of the obturator nerve supplies its capsular ligament, and is ultimately distributed to the ligamentum teres ; and, finally, that a branch from the sacral plexus sup- plies the hip joint at its posterior aspect, after sending fila- ments to the gemelli, the quadratus f em oris, and the obtu- rator internus muscles. The study of the anatomy of Joints is of particular importance to the diagnostician, since it fre- quently explains how remote sympathetic pains may be dependent upon irritation of articular branches of a nerve, whose terminal cutaneous filaments are distributed to other regions, often far removed from the joint which it supplies. We know that disease of the hip joint, which is, perhaps, one of the most frequent which we meet with in practice, is often manifested, in its early stages, by a pain which is re- ferred to the knee ; and we can understand, from what has previously been said, that this sensation of pain must be transmitted through one of three sources, viz., the obturator, anterior crural, or the sciatic nerves. CLINICAL POINTS PERTAINING TO THE NERVES DERIVED FROM THE SCIATIC, OR TO THE SCIATIC NERVE ITSELF. The morbid conditions of the sciatic nerve or its branches which are most frequently met with comprise : 1, neuralgia^ which may be articular or confined to the direct course of the sciatic nerve ; 2, spasmodic affections of the muscles supplied by the sciatic nerve or its branches ; and 3, paralysis of the different muscles supplied by the various nerve trunks. SCIATICA. This type of neuralgia — to which the name "malum Co- tunnii " is sometimes applied — may affect the greater portion of the back part of the thigh, a part of the gluteal region, the knee joint and patella, the anterior, lateral, and posterior surfaces of the leg, and the whole of the foot, with the excep- SCIATIC NEURALGIA. 479 tion of its internal border, which derives its nerve supply from the saphenous branch of the anterior crural nerve. It is seldom that all of these regions are affected at the same time, since the nerve may be subjected to a source of irrita- tion which affects only individual branches. The most fre- quent seat of pain is confined, as a rule, to the posterior sur- face of the thigh and the upper half of the calf of the leg ; but the external surface of the lower half of the leg and the corresponding part of the foot, as well as the sole, are often the seat of a neuralgic pain which is of a severe type. The disease is usually unilateral in character, and, if bilateral, a central cause may be suspected. Among the causes of this type of neuralgia may be men- tioned exposure to cold and dampness, malarial affections, inflammations of the nerve, injuries, pressure of tumors or inflammatory exudations, violent exertion, disturbances of the venous circulation of the pelvis, and mechanical pressure from sitting upon hard or uncomfortable seats, uterine dis- placement, pelvic tumors, aneurism, and hernia. The beginning of this disease is usually associated with premonitory symptoms, among which may be mentioned a sensation of stiffness, cold, or heat in the affected regions, with occasional feelings of formication, or a fluid trickling over the skin. Soon painful electric pains are experienced, which show a marked paroxysmal character. These attacks occasionally occur without warning or premonitory symp- toms. The pain is remarkably violent, and of a tearing and lancinating character, and usually follows the direction of the nerve trunk which is affected. It often changes its seat of greatest intensity, and the lines which connect the spots of greatest x)ain will generally conform to the anatomical course of the affected nerve. The pain is usually markedly increased by motion of the muscles, and the paroxysms seem to be ex- cited by the most trivial causes, such as a draft of cold air, coughing, sneezing, sudden bending of the body, the contact of the clothes with the skin, or straining during the acts of defecation or micturition. If the whole area of the distribu- 480 THE SPINAL NERVES. tion of the sciatic nerve be involved, the pain occurs with special violence first in one and then in another branch, while the posterior branches of the sacral nerves may be also impli- cated, and the patient complain of violent pain in the sacrum and the loins. 8... ..J. - jl^ 12 Fig. 176. — TJie motor points on tlic posterior aspect of the thigh. 1, branch of the inferior gluteal nerve to the gluteus maximus muscle; 2, sciatic nerve; 3, long head of biceps muscle ; 4, short head of biceps muscle ; 5, adductor magnus muscle ; 6, scmi-tendinosus muscle ; 7, serai-membranous muscle ; 8, tibial nerve ; 9, peroneal nerve; 10, external head of gastrocnemius muscle; 11, soleus muscle; 1 2, internal head of gastrocnemius muscle. As has been mentioned in other forms of neuralgia, certain painful points may usually be detected, which are diagnostic of neuralgia from those severe pains which accomi)any the early stages of locomotor ataxia. The most constant point of sensitiveness to pressure is stated by Valleix to correspond to the posterior superior spine of the ilium ; another usually ex- SPASM OF THE LOWER LIMB. 481 ists where the nerve escapes from the cavity of the pelvis ; a third is often found at the lower border of the gluteus maxi- mus muscle, where the posterior cutaneous branch emerges ; the fourth corresponds to the head of the fibula, where the tibial nerve is given off ; a fifth point is often discovered be- hind the internal malleolus ; and, finally, there are frequent inconstant points in the thigh, on the calf of the leg, and on the dorsum of the foot, all of wMch correspond to localities where cutaneous branches either divide or perforate some fascia. In connection with this neuralgic pain, certain motor symptoms are frequently developed. These comprise a pe- culiar limping gait, a mode of carrying the leg which is quite diagnostic, cramp of various degrees, and possibly convul- sions, which are sometimes very violent. These symptoms are the result of direct and reflex irritation, and may be the forerunners of a condition of paresis or of actual paralysis. Among the vaso-motor disturbances which accompany this disease may be mentioned paleness and coldness of the skin, in some instances accompanied by numbness and chilly sen- sations, and in other cases redness and heat of the skin, with increased perspiration, increased growth of the hair, herpes zoster along the course of the affected nerve, a saccharine con- dition of the urine, and hypertrophy and atrophy of the muscles. Sciatica is to be diagnosed from disease of the hip Joint ; from locomotor ataxia in its early stages ; from muscular rheumatism ; and the pains of spinal disease, affecting the lateral columns, when the patient is subjected to extreme ex- ertion. SPASM OF THE LOWER LIMBS. The muscles of the hip — especially the psoas, iliacus, quadratus lumborum, and adjacent muscles of the anterior surface of the thigh — may be the seat of tonic spasm, which has been named by Stromeyer "spasmodic contracture of the hip." It may follow an inflammation or neuralgia of the hip joint, psoas abscess, or diseases of the lumbar vertebrae. In 482 THE SPUSTAL NERVES. this condition, the thigh is strongly flexed, the pelvis tilted upward, and the limb shortened ; while passive extension creates a deviation of the body toward the affected side, and is extremely painful. In rare instances, tonic and clonic types of spasm are ob- served in the extensor and adductor muscles of the thigh, as the result of neuralgia of the knee joint and certain spas- modic diseases of a central origin. The flexor muscles of the leg may be affected with spasms in spinal affections, hysteria, diseases of the knee joint, and in inflammation of its adjacent muscles. Fig. 177. — Tlic motor points on the antcHor aspect of the thigh. 1, crural nerve ; 2, obturator nerve ; 3, sartorius muscle ; 4, adductor longus muscle ; 5, branch of the anterior crural nerve for the quadriceps extensor muscle ; 6, the quad- ric lis muscle ; 7, branch of anterior crural nerve to the vastus internus muscle ; 8, tensor vaginoe femoris muscle (supplied by the superior gluteal nerve); 9, external cutaneous branch of anterior crural nerve ; 10, rectus femoris muscle; 11, 1?, vastus externus muscle. In rare cases, the anterior muscles of the leg, which are supj)lied by the peroneal nerve, are affected with spasms as PARALYSIS OF SCIATIC NERVE OR ITS BRANCHES, 483 the result of exposure to cold or dampness, over-exertion of the lower limbs, or paralysis of the antagonistic muscles; while the muscles supplied by the posterior tibial nerve, as well as those of the sole of the foot, are more frequently affected as the result of spinal affections, joint diseases, over- exertion, paralysis of other muscles, and by the reflex action of cholera. PARALYSIS OF MUSCLES SUPPLIED BY THE SCIATIC KERVE OR ITS BRANCHES. When we consider how extensively this nerve is distrib- uted, and its exposed situation in various portions of its course, as w^ell as its intimate relations to the organs of the pelvis, we can better appreciate the reasons for the frequency, on the one hand, and the importance, on the other, of the paralysis which may affect it or its branches. Among the causes of this form of paralysis may be enumerated all those conditions of the trunk which are capable of producing press- ure upon the origin of the nerve ; all forms of accidents which may result in laceration or section of the main trunk or any of its branches ; the development of tumors in the course of the nerve ; dislocations of bone ; the compression of cicatrices ; rheumatic conditions, from chilling or wetting of the lower extremities ; surgical operations ; and spinal diseases which impair its point of origin at the lumbar enlargement of the cord. If the peroneal nerve be alone affected, the foot can not be flexed or abducted ; neither can it be completely adducted. The dependent position of the foot, which hangs downward, interferes seriously with the act of walking, since the toe trips upon every slight elevation. In order to walk, the patient is compelled to lift the foot by flexion at the hip joint, and places it insecurely upon the ground with the outer border of the toes first, thus producing a gait which is pathognomonic of this special type of paraly- sis. The arch of the foot becomes flattened from a loss of power in the peroneus longus muscle ; the great toe can not 484 TEE SPINAL NERVES. be extended, since the extensor longns pollicis is paralyzed ; flexion of the foot is impaired, since the extensor communis digitorum no longer acts ; and the abduction of the foot is rendered impossible, if the peroneus brevis be paralyzed, although the extensor communis digitorum may assist in this act coincidentally with dorsal flexion of the foot. Fio. 178. — TJic motor points on the inner aspect of the kg. 1, intemal head of gastrocnemius muscle ; 2, soleus muscle ; 3, flexor communis digito- rum muscle ; 4, posterior tibial nerve ; 5, abductor pollicis muscle. If the tlMal nerve be paralyzed, a loss of power in the muscles of the calf is indicated by an inability on the part of the patient to extend the foot and to produce flexion and a lateral movement of the toes. Thi'is the patient is no longer able to stand upon the toes, while, in consequence of a sec- ondary contracture of the muscles situated upon the anterior PARALYSIS OF SCIATIC NERVE OR ITS BRANCHES. 485 surface of the leg, the foot is made to assume a position which has been compared to the shape of a hook. The tibialis pos- ticus muscle no longer assists in adducting the foot and rais- ing its inner border ; the flexor communis digitorum can no longer flex the two distal phalanges of the toe, while paraly- FiG. I'ZQ. — The motor 'points on the outer aspect of the leg. 1, peroneal nerve ; 2, external head of gastrocnemius muscle ; 3, soleus muscle ; 4, ex- tensor communis digitorum muscle ; 5, peroneus brevis muscle ; 6, soleus muscle ; 7, flexor longus pollicis ; 8, peroneus longus muscle ; 9, tibialis anticus muscle ; 10, ex- tensor longus pollicis muscle; 11, extensor brevis digitorum muscle; 12, abductor minimi digiti muscle ; 13, deep branch of the peroneal nerve to the extensor brevis digitorum muscle : 14, 14, 14, dorsal intcrossei muscles. sis of the flexor longus pollicis deprives the patient of the power of flexing the great toe. A lateral motion of the great 33 486 THE SPINAL NERVES. toe is no longer possible, since the power of the adductor and abductor pollicis muscles is abolished, while paralysis of the interossei muscles (as mentioned also in connection with the hand) renders it impossible for the patient to flex the first phalanx, or extend the two distal phalanges of the toes, or separate the toes from each other. The peculiar position of the foot which results from this paralysis resembles that de- scribed in connection with the upper extremity as the " claw hand," since the first phalanx is abnormally extended, the second and third are strongly flexed, the toes are tightly compressed together, and their bulbous ends no longer touch the ground. The weight of the body in a standing position is borne upon the heads of the metatarsal bones. Hence, some pain and inconvenience are experienced after long standing or walking. Paralyses of the sciatic nerve are accompanied, as a rule, by disturbances of the sensibility of the affected parts. An- aesthesia commonly exists over the regions supplied by the motor nerves to the muscles which are paralyzed ; hence, this symptom may serve as a guide, in some cases, to the seat of the lesion which has created the paralysis. In addition to these disturbances of sensibility, you may often notice changes in the circulatory apparatus in the form of coldness of the skin, cyanosis, stasis in the veins, and a mottling of the part with bluish-red streaks. The tropJiic disturbances which are commonly met with in severe forms of paralyses of the peripheral branches of the sciatic nerve comprise serious bed-sores on the heels, ankles, and over the sacrum ; ulceration of the skin ; eruptions of herpes and pemphigus ; and, finally, marked atrophy of the muscles. When the sciatic nerve is affected by a spinal le- sion above the cauda equina, the rectum and bladder are fre- quently completely paralyzed. INDEX. ^sthesodic system, 313, systematic lesions of, 315. Ageusia, its tests and clinical significance, 236. Amaurosis, 123, 126, 144. Amblyopia, 49, 50, 127. Amyotrophic lateral sclerosis, 329. Anaesthesia, its significance when combined with hemiplegia, 73. Anaesthesia of locomotor ataxia, 320. Aneurismal cough, 254. Angular gyrus, guide to, 72. its function, 50, 52. Anosmia, its causes, and clinical significance, 102. Aphasia, its relations to embolism, 89. surgical relief of, 73, 74. traumatic, 73. varieties of, and causes, 32. Aqueduct of Fallopius, 177, 1S2. lesions within, 196. Aqueduct of Sylvius, its special center, 58. Arm, motor points of (cuts), 415, 416. Arnold's nerve, 239. Artery, middle cerebral, distribution of, 37. Astigmatism, its tests and clinical signifi- cance, 110, 111. Ataxia, changes of the pupils in, 323. locomotor, 316. " reflex tests " of, 323, 324. symptoms of, 320, 321, 322. tests for, 321, 322, 323. Auditory nerve, 198. Auditory vertigo, its clinical significance, 211. Basal ganglia, effects of lesions of, 81. Bell, respiratory nerves of, 187. Bell's paralysis, 180, 181, 191, 192, 193, 194. its effect on smell, 102. its varieties, causes, and symptoms, 192, 193, 194, 195. Bent arm, its clinical significance, 387. Bladder, its relations to focal lesions of the spinal cord, 345. Boulimia, its clinical significance, 257. Brachial plexus, 378. branches of inner cord of, 383, 384. branches of outer cord of, 382. branches of posterior cord of, 384. communications of, 382. cords of, 378, 379, 380. - — (cuts), 379, 380. Brain, its anatomy, functions, and clinical aspects, 19. clinical subdivisions of, 80, 81, 82. component parts of, weight of, 22, 23, 24. convolutions and sulci of, 75, 76, 77. effects of destructive lesions of gray matter of (general summary), 89. effects of diffused lesions of, 90. effects of effusion into lateral ventri- cles, haemorrhage, and softening of, 38. effects of intra-cranial pressure, 82. effects of irritative lesions of, 89. effects of lesion in the median line of, 82. effects of lesion of one lateral half of (general summary), 82. embolism of, 34. fourth ventricle of, its nuclei, 66. functions of the cerebellum, 61. function of cerebral convolutions (gen- eral deductions), 56. 488 INDEX. Brain, functions of crura cerebri, 59. functions of internal capsule of, 26, 91. function of lower portions of, 56. functions of medulla, 65, 66. functions of pons Varolii, 59, 61. ganglia of, 19, 20. general propositions relative to effects of lesions of its component parts, 81. general summary of its physiology and the effects of lesions of its sub- stance, 82, 83, 84, 85. gray matter of, 19, 20. growth of, 23, 24. inferior aspect of (cut), 22. in profile (cut), 20, 21. special centers of motion of (cut), 39, 41. transverse vertical section of (cut), 22. weight of, 22, 24, 25. Broca, center of, 32, 33. center of, surgical guide to, 71. the alveolo-condyloid plane of, 69. Canal, intestinal, effect of section of pneu- mogastric upon, 253. Canals, semicircular, 200, 204, 206, 207. semicircular, effects of section of, 215, 216, 217, 218. semicircular, their relations to audi- tory vertigo, 215. Cardialgia, 257. Central myelitis of spinal cord, 338. Cerebellar ataxia, 64. vertigo, 62. Cerebellum, effects of lesions of (general summary), 82. functions of, 61. its numerous connections, 63, 64. vertigo and ataxia dependent upon, 63,^64, 65. Cerebral thermometry, 84. topography, its surgical beaiings, 68. Cerebro-spinal axis, 5. fluid, 292. fluid, its normal quantity and func- tions, 292, 293. fluid, its relation to consciousness, 45. nerves, 5-9. Cerebrum, its anatomy, functions, and clini- cal aspects, 25. caudate nucleus of, 48. centers of motion of, 28. construction of its gray matter, 75. Cerebrum, converging fibers of, 26. convolutions of (cut), 31. convulsions due to lesions of, 47. cortex of, its centers, 32. course of nerve impulses in (diagram), 53. effects of lesions of central portions of, 92. effects of lesion of cortex (general summary), 82. effects of lesions of internal capsule of, 91. effects of lesions of motor area of, 37, 38. effects of lesions of the white center of the hemispheres, 81. effects of removal of, 29. excitable regions of its cortex, 85. frontal lobes of, 35. functions of, 27. functions of frontal lobes of, 35. functions of special motor centers of, 40, 42. guides to basal ganglia of, 71. gyri of, 77, 78, 79. haemorrhage of, its effects upon, 30. hemispheres of, functions of, 28. internal aspect of (cut), 25. internal capsule of, 26. irritability of, 28. irritative lesions of motor area of, 4 6. its basal ganglia, 26. its convolutions, 75. lenticular nucleus of, 48. lobes of, 7B. .lobules of, 76. lobules of, their situation, 79. motor regions of, 36. motor and sensory tracts of (cut), 35. occipital lobe of, its functions, 50. principal fissures of, 77. results of lesions of frontal lobe of, 35. sensory lesions of, 48. sensory regions of cortex of, 86. softening of, its effects, 30. special centers of motion of, 39. structure of convolutions of (cut), 83. sulci of, 76. temporo- sphenoidal lobes of, and their functions, 51. Cervical plexus of nerves, 364. deep branches of, 369. its situation, 368. INDEX, 489 Cervical plexus, superficial branches of, 366. Ciieek, hypertrophy of, its causes, 163. Chorda tympani nerve, its relations to taste, 160. Choreic movements, their clinical significance in connection with cerebral lesions, 91. Choroiditis, its effect on vision, 143. Ciliary muscle, its function and nerve distri- bution, 129, 132, 133. Cilio-spinal center, 14Y, 3?1, 311, 351. its relations to focal lesions of cord, 343. Claw-hand deformity, 330. Cochlea, 204, 207. Coitus, its relation to spinal disease, 347. its relation to small sciatic and pudic nerves, 466, 468. Color blindness, 116. Column of Burdach, sclerosis of, 315, 316. Column of GoU, sclerosis of, 315, 316. Column of Tiirck, sclerosis of, 315, 326. Conjunctiva, its nervous supply, physiology of, 171. Consciousness, its relation to brain lesions, 45. Convulsions of cerebral origin, 47. Cornea, ulceration of, its relations to fifth nerve, 170. Corpora quadrigemina, effect of lesions, 91. their functions, 58. Corpus striatum, 26. its functions, 54. subdivisions of, 26. Corti, membrane of, 210. organ of, 201, 208, 209. Cranial nerves, 9-95. Cranium, surgical guides of, 68, 69, 70, 71. Crural neuralgia, 450. Crus cerebri, its functions, 59. Deaf-mutism, 220. Defecation, center of , 311. its relations to focal lesions of the spi- nal cord, 345, 347, 352. Deglutition, center of, 67. center of, reflex acts of, 233. effects of section of fifth nerve upon, 160. excitory nerve of, 231. its relations to glosso-pharyngeal nerve, 223. its relation to the otic ganglion, 174. Deglutition, mechanism of, 226, 227, 228, 229, 230, 231, 232, 233. muscles connected with, 370. relations of hypo-glossal nerve to, 277. relations of spinal accessory nerve to, 264. Diabetes, center of, 67. Diaphragmatic tetanus, 376. Digestive tract, effects of section of pneu- mogastric nerve upon, 251. Diplopia, its clinical significance, 148, 149. Duchenne's disease, 149-196, 234, 278, 279. its relations to tetanoid paralysis, 330. Dyspnoea, its relations to focal lesions of the spinal cord, 344. Ear, external, 201. internal, 204. internal, fluids of, 205. middle, 201. relations of muscles of, to hearing, 187. Earache, its diagnostic importance, 171. its relations to fifth nerve, 170. Eighth nerve (see Nerve, Auditory), 198. Eleventh nerve (see Nerve, Spinal Acces- sory), 259. Embolism of brain, 34. Epilepsy, spinal, 345. Erection, center of, 311. Eustachian tube, function of, 202. its clinical points of interest, 217, 218. Eye, in facial paralysis, 190. its relations to facial diplegia, 197, 198. Eyeball, center of movements of, 139. motions of, 135, 136, 137, 138, 139, 140. Eyelid, effect of closure of, on lachrymal ap- paratus, 121. mechanism of its closure, 121. Eyes, bilateral deviation of, in cerebral le- sions, 40. . oscillatory movements of, their clinical significance, 215. Face, in facial diplegia, 197. motor centers of, 42, 43. motor points of (cut), 282. paralysis of muscles of, 191, 192, 193, 194. relations of cervical plexus to expres- sion of, 368. relation of facial nerve to expression of, 189. spasm of muscles of, 190, 191. 490 INDEX. racial diplej^ia, 196, 197. Facial nerve (see Nerve, Facial), 177. function of chorda tympani branch of, IGO. Facial neuralgia, IGl. Fallopius, aqueduct of, 177, 182. aqueduct of, its relations to facial pa- ralysis, 193, 194. Fascia of chest, nerve distribution of, 368. of forearm, its nerve supply, 388. of leg, its relation to cutaneous nerves, 474. its nervous supply, 447. Fasciae, nervous distribution to (general axiom), 12, 13. Fibers of Remak, 9. Fifth cranial nerve (see Nerve, Trigeminus), 151. First cranial nerve (see Nerve, Olfactory), 95. Fissure, calcarine, of cerebrum, 80. calloso-marginal, of cerebrum, 80. external parieto-occipital, its relations to the lambdoidal suture, 68. external parieto-occipital, its eituation, 77. external parieto - occipital, surgical guide to, 71. internal parieto-occipital, of cerebrum, 80. of Rolando, 37, 42. guide to, 70, 72. its relation to the coronal suture, 68. its situation, 77. of Sylvius, guides to, 71, 72. its situation, 77. its surgical importance, 77. Foot, its attitude in tibial paralysis, 485, 486. Forearm, motor points of (cut), 417, 418. Fourth cranial nerve (see Nerve, Trochlea- ris), 149. Fremitus of fingers in paralytic dementia, 281. Gait of locomotor ataxia, 321. of peroneal paralysis, 483, 484. of sciatic paralysis, 481. of tetanoid paraplegia, 330. Ganglion, ciliary, 174, 175. jugular, 222. jugular, of pneumogastric, 239. lenticular, 174, 175. Meckel's, 174, 175, 183, 186. Meckel's, excision of, 173. Ganglion, of Luschka, 372. of root of pneumogastric, 239. of trunk of pneumogastric, 239. ophthalmic, 174, 175. ophthalmic, its relation to sixth nerve, 176. otic, 174, 175, 183, 186. submaxillary, 174, 175. of Andersch, 222, of Gasser, 229. Ganglia, basal, of cerebrum, 26. basal, of cerebrum, effects of destruc- tion of, 56, 57. basal, of cerebrum, effects of lesions of, 81. basal, of cerebrum, their functions, 54. connected with fifth cranial nerve, 173, 174. of the brain, 19, 20. — - of the fifth nerve (table of), 175. General axioms of nerve distribution, 11, 12, 13. Genito-urinary center, 301, 311. Glands, cervical, relations of their enlarge- ment to fifth nerve, 170. Globus hystericus, 254. Glossoplegia, 278, 279. Glottis, respiratory movements of, 264. Gluteal paralysis, 461. Gubler, line of, 183, 192. Hair, sudden blanching of, 169. Hand, its relation to paralysis of median nerve, 397. its relation to paralysis of musculo- spiral nerve, 415, 416. its relation to paralysis of ulnar nerve, 403, 404. motor centers of, 43. motor points of (cut), 417, 418. Handwriting, its modifications in paralytic dementia, 281. Head, nerve supply to posterior portion of,! 366, 367. Hearing, centers of, 86. effects of section of fifth nerve upon, 160. general view of organ of, 200. its relations to facial paralysis, 194. its relation to otic ganglion, 174. I mechanism of, 202, 203, 204, 207, 208, I 209, 210. I relations of muscles of ear to, 187. INDEX, 491 Hearing, special centers of, 52. Heart, acceleratory center of, 342, 343, 344. effects of section of pneumogastric upon, 251. inhibitory center of, 67. Hemianopsia, its varieties and causes, 123, 124. Hemiparaplegia, 348, 352. Hemiplegia spinal, 348, 350. Hiccough, 374, 375. its relations to focal lesions of spinal cord, 343. Huguier, canal of, 182. Hypergeusia, its tests and clinical signifi- cance, 235. Hyperopia, its effects on health, 109, 110. Hyperosmia, its causes and tests, 102. Incoordination, theories of origin of, 325. Intercostal neuralgia, 430. Internal capsule of the brain, 26, 48. effects of lesions of, 44, 49, 91. Iris, its nervous supply and movements, 130, 131, 134, 135. reflex action of, and its clinical bear- ings, 135. relations of blood-vessels to move- ments, 134. Island of Keil, effects of lesions of, 86. its situation, 79, 80. Jacksonian epilepsy, 47. Kinesodic system, 313. Kopp's asthma, 254. Labyrinth, its anatomy and functions, 204. Lachrymal apparatus, its relation to facial paralysis, 198. Larynx, effects of section of pneumogastric nerve upon, 249. Lenticular nucleus, 48. Liver, effects of section of pneumogastric nerve upon, 252. Lobe, frontal, of cerebrum, 35. frontal, of cerebrum, fifth convolution of, in criminals, 77. frontal, of cerebrum, its convolutions or gyri, 78. occipital, of cerebrum, its convolutions or gyri, 79. occipital, of cerebrum, its functions, 50. Lobe, parietal, of the cerebrum, its convo- lutions or gyri, 78. Lobule, occipital, its situation, 80. para-central, 37. its situation, 80. Lobulus centralis, its situation, 79. quadratus, its situation, 80. Local tenderness of skin, significance of, 12. Locomotor ataxia, 316. Locus cseruleus, 175. Lower extremity, motor centers of, 40, 42. Lumbar plexus, 435, 436. tables of branches of, 437, 438. Lumbo-sacral cord, 458. Lungs, effect of section of pneumogastric nerve upon, 250. Macropsia, its clinical significance, 142, 143. Macula lutca, 105. Malum Cotunnii, 478. Mastication, effects of section of fifth nerve upon, 160. its alteration in Duchenne's disease, 279. Mastodynia, 432, 433. Meckel's ganglion, 174, 175. Median nerve, trophic effects of paralysis of, 398. Medulla oblongata, respiratory center of, its clinical relations, 342. centers of, and their functions, 66, 67. functions of, 65. nerve, nuclei of, 66. Mcgalopsia, its clinical significance, 142, 143. Meniere's disease, 62, 120, 211. Meningo-encephalitis, 90. Meso-cephalon, motor and sensory tracts of (cut), 35. Micropsia, its clinical significance, 142, 143. Micturition, center of, 311. its relations to focal lesions of the spinal cord, 345, 347, 352. Monoplegia, surgical relief of, 74. traumatic and surgical aspects, 74. types of, 45, 46. Motor nerves, methods of termination (cut), 10. Motor oculi nerve, 127. its clinical relations, 142. its origin and course, 127, 128. its relations to the perception of dis- tance, 140. 492 INDEX. Motor oculi nerve, physiology of its distri- bution, 131, 132, 133. symptoms of paralysis of, 145. Motor points of upper extremity (cut), 416, 416, 417, 418. Mouth, changes due to spasm of, 165. changes in Bell's paralysis, 180. motor centers of, 42. Muscae volitantes, their causes, 115. Muscle, buccinator, its relations to degluti- tion, 227. buccinator, physiology of action, 188, 189. platysma, physiology of its action, 188. quadriceps extensor, spasm of, 448. stapedius, 181. stapedius, function of, 217. sterno-mastoid, its nerve supply, 266. sterno-mastoid, paralysis of, 270, 271. sterno-mastoid, tonic and clonic spasm of, 268, 269. tensor tympani, function of, 204, 217. tensor tympani, its relations to facial paralysis, 194. trapezius, its nerve supply, 266. trapezius, paralysis of, 271, 272. trapezius, tonic and clonic spasm of, 268, 269. Muscles, causes of contracture after paraly- sis of, 346. extensor and adductor groups of thigh, spasm of, 482. flexor group of foot, spasms of, 482, 483. flexor group of leg, spasm of, 482. gluteal, paralysis of, 461, 462. gluteal, spasms of, 461. of the hip, spasm of, 452, 481. of the thigh, atrophy of, 450. of the thigh and leg, their physiological groupings, 454, 455. of voice, nervous supply of, 263. Jlyelitis, central, of spinal cord, 338. of anterior horns of spinal cord, 331. polio-, 332. Myopia, its cjffects, 109, 111. Nerve, abducens, 175, 176. abducens, clinical relations of, 176, 177. abducens, functions of, 176, 177. accessory obturator, 437, 438. Nerve, accessory obturator, its distributions and functions, 456, 457. anterior crural, 437, 438. anterior crural, its clinical relations, 447. anterior crural, its distributions and functions, 444, 445. anterior crural, its relations to joints, 444, 445. anterior interosseous, 382. anterior tibial, 472. Arnold's, 239. auditory, 198. auditory, anasthesia of, 220. auditory, clinical points afforded by, 211. auditory, diagram of, 198. auditory, hyperaesthesia of, 219. auditory, its origin, 198. — — auditory, peculiarity of fibers of, 199. cardiac, 245. cervical, clinical points pertaining to, 372. cervico-facial, 179. 182, 188. chorda tympani, 182, 183, 234. chorda tympani, diagram of, 183, 185. chorda tympani, function of, 225. chorda tympani, its origin, 179. chorda tympani, its relations to facial paralysis, 193, 194. chorda tympani, its relation to the sub- maxillary gland, 174. chorda tympani, its relations to taste, 160. ciliary, 153, 154. circumflex, of arm, 378, 384, 406. circumflex, of arm, its clinical rela- tions, 407. circumflex, of arm, its distribution and functions, 406, 407. cochlear, 200. communicans noni, 275, 276, 362, 364. communicans noni, its surgical rela- tions, 369. compound, of the head, 172. cutaneous, of ear, 158. dental, inferior, 153, 154. depressor, of heart, 238, 239, 245, 263. depressor, of heart, its relations to spinal accessory nerve, 265. dcscendcns noni, 275, 276. dorsal, of penis, 459. INDEX. 493 Nerve, dorsal, of penis, its distributions and functions, 467, 468. efferent, 7. excitory, of deglutition, 231. external anterior thoracic, 378, 382, t385. external cutaneous, of the arm, 378, 382, 385. external cutaneous, of the thigh, 437, 438. external cutaneous, of thigh, its distri- bution and functions, 442, 443. external popliteal, 459, 472. external respiratory, of Bell, 378. external saphenous, 472. facial, 177. facial, clinical points afforded by, 190. facial, communications of, 178, 179. facial, course of, 177. facial, diagram of, 179. facial, functions of, 179, 180. facial, lingual branch of, 182, 184. facial, its relations to Duchenne's dis- ease, 280. facial, origins of, 177. facial, paralysis of, 180. facial, relations to fifth nerve, 183. facial, table of branches of, 182. fibers (cut), 5. frontal, 153, 154. genito-crural, 437, 438. genito-crural, its distribution and clini- cal relations, 443, 444. glosso-pharyngeal, 220. glosso-pharyngeal, clinical points of interest of, 234. glosso-pharyngeal, effects of section of, 225. glosso-pharyngeal, its origin and rela- tions, 221. glosso-pharyngeal, table of branches of, 225. great auricular, 362, 363, 364, 366, 367. great occipital, 362, 363, 366, 367. great sciatic, 458, 459. great splanchnic, its relation to pain, 426. gustatory, 153, 154. hypo-glossal, 272. hypo-glossal, clinical points pertaining to, 277. Nerve, hypo-glossal, communications of, 273, 274, 275. hypo-glossal, effects of section of, 277. hypo-glossal, general function of, 272, 276. hypo-glossal, its relations to degluti- tion, 227, 228, 277. hypo-glossal, origin of, 272, 273. ilio-hypogastric, 437, 438. ilio-hypogastric, its clinical relations, 440. iliohypogastric, its distributions and functions, 439, 440.^ ilio-inguinal, 437, 438. ilio-inguinal, its clinical relations, 440. ilio-inguinal, its distribution and func- tions, 439, 440. inferior dental, rules for section of, 173. inferior gluteal, 459. inferior hemorrhoidal, 459. inferior hemorrhoidal, its distributions and functions, 467, 468. inferior maxillary, 153, 154. inferior pudendal, 459. inhibitory, of vaso-motor center, 247. intercostal, physiology of, 421, 422, 423, 424. internal anterior thoracic, 378, 383, 385. internal cutaneous, of arm, 378, 383, 398. internal cutaneous, of the thigh, 438. internal popliteal, 459, 472. internal saphenous, 438. Jacobson's, 225. lachrymal, 153, 154. laryngeal, 242, 243. lesser internal cutaneous, 378, 383, 398. long saphenous, 438. long saphenous, its distribution and physiology, 447. median, 378, 382, 391. median, its clinical relations, 395. median, its distribution and functions, 393, 395. median, its surgical relations, 393, 398. middle cutaneous, of the thigh, 438. motor-oculi, 127. motor-oculi externus, 175, 176. muscular, of brachial plexus, 378. musculo-cutancous, 382,385. 494 INDEX. Nerve, musculo-cutaneous, of arm, its clinical relations, 390, 391. musculo-cutaneous, of arm, its physio- logical relations, 386, 387, 388. musculo-cutaneous, of leg, 472. musculo-spiral, 378, 384, 408. musculo-spiral, its clinical relations, 412. musculo-spiral, its course and distri- bution, 4