COLUMBIA LIBRARIES OFFSITE HEALTH SCIENCES STANDARD HX00025070 ^m M TK H A si cc to sc of ef ;ir Columbia Mntoerattp intfjc Citp of il eto fforfe College of ^fjpgtctans; anb burgeons (Stben op ifltes <&usfgie Cllteon in mentor? of 3Br. Crnest Militant gu?al 1918 AN ATLAS OF THE NORMAL AND PATHOLOGICAL NERVOUS SYSTEMS. TOGETHER WITH A SKETCH OF THE ANATOMY, PATHOLOGY, AND THERAPY OF THE SAME. BY DR. CHRISTFRIED JAKOB, PRACTISING PHYSICIAN IN BAMBERG, FORMERLY FIRST ASSISTANT IN THE MEDICAL CLINIC AT ERLANGEN. WITH AN INTRODUCTION BY PROF DR AD. v. STRUMPELL. (Translated and JEOitcO (autborl3eD) bg JOSEPH COLLINS, M.D., INSTRUCTOR OF NERVOUS AND MENTAL DISEASES, NEW YORK POST-GRADUATE MEDICAL school; VISITING PHYSICIAN TO THE HOSPITAL FOR NERVOUS DISEASES; ATTENDING PHYSICIAN TO ST. MARK'S H08PITAL. NEW YORK: WILLIAM WOOD & COMPANY, 1896. PREFATORY NOTE. During his tenure of assistantship in the medical clinic of this place Dr. Jakob has busied himself in a most industrious manner with the normal and patho- logical anatomy of the nervous system. By means of most approved methods of investigation he has prepared with great care a large collection of histo- logical preparations, and these in connection with the uncommon talent for drawing which he possesses have put him in a position to prepare the following atlas almost entirely from his own preparations and draw- ings. Every unprejudiced observer will, like my- self, I think, be convinced that the illustrations con- vey everything that can be thus given. They give the actual relationships in a clear and lucid manner, and they depict with great completeness nearly all the numerous important discoveries which the last dec- ades have brought forth. The student as well as the practical physician who wishes to keep in touch with the advance which medical science has made from the standpoint of the neurologist is given the oppor- tunity to get a clear conception of it by means of this atlas. The intimate relationship existing between clinical pathology on the one hand and normal and pathological anatomy on the other is scarcely so strik- iii PREFATORY NOTE. ing or apparent in any other branch of medicine as in neuropathology. The individual study of the normal anatomical and pathological conditions in connection with the illus- trations which are detailed but not schematic, true representations of the parts as they exist, cannot help but be of the greatest didactic use. I wish heartily for this work, which the author and publisher have spared no pains to make really good and useful, the success which it deserves. Dr. Strumpell. iv AUTHOR'S PREFACE. In the present atlas I have endeavored to portray an important chapter of medicine, which usually re- mains, for the majority of students and physicians of all classes, foreign and unenjoyable. I have, more- over, endeavored to take this bugbear and to place its usual normal and pathological anatomy in compre- hensible form. It has been my idea to make easy of comprehension for students the clinical picture as seen at the bedside and the processes on which it de- pends ; and at the same time to make it possible for the practical physician, who has heretofore stood aloof from this subject, to understand the meaning of the most important recently developed facts of neurology. To this end I have made the freest use of illustrations. In the text everything unnecessary, especially of a histological nature, I have relegated as much as pos- sible to the background. The illustrations serve substantially to show the facts as they actually exist, without being schematic. The exhibition of stained specimens was unavoidable. Unstained fresh specimens have, however, been used. The actual study of the fresh brain can be substituted by no form of illustration, even photographic. The reproduction by lithographs and woodcuts has been author's preface. carried out with unusual care under my entire con- trol. The source of the illustrations is the pathological collection which I have been able to arrange during my assistanceship of several years in the medical clinic at Erlangen from its very rich material. I owe the greatest thanks to my former respected chief, Prof. Dr. Strumpell, for the liberality with which he has always placed everything necessary at my disposal, for the gracious support which he has al- ways given me in every question, and in this place I may be permitted to make acknowledgment of the same. A few words on the study of the illustrations : From the natural limitations of the pages devoted to text it has been impossible to describe in detail the wealth of facts which are to be seen in the figures. The pic- tures, therefore, contain decidedly more material than is explained. I consider this indeed rather an advantage for the book. I hope that by this means actual close study will be directed toward the illustrations. And thus the formation of an independently reached decision of the greatest importance for our science may be made possible. The material presented appears to me in a certain way to tend in that direction. Christfr. Jakob. Bamberg, Summer, 1895. TRANSLATOR'S PREFACE. At the request of the publishers I have undertaken the translation of Jakob's explanatory atlas of the nor- mal and diseased histology of the nervous system because of my conviction that the volume would be of assistance to students and to the general prac- titioner. Feeling it a duty to the author, I have en- deavored to make the translation a literal one so far as it was consistent with lucidity. This has been done in some instances at the expense of style and smoothness of diction. A word of explanation is necessary in reference to the translation of certain words. Gehirnstamm, a word proposed by Meynert to include that part of the brain left after removal of the hemispheres and basal ganglia, has been rendered by the word brain stem as a rule, exceptionally by the word brain axis. Anlage, an extremely useful but untranslatable word which by some authors has been taken over bodily into English, has been translated in most instances by the word proton, a term suggested by Prof. B. G. Wilder, and the paronymization protal — two eupho- nious, significant words. Occasionally it has been rendered "' primary constituent," especially when used in biological connection. Such descriptive words as vii TRANSLATOR'S PREFACE. " Faserendauf splitterung" have been rendered liter- ally terminal arborization of fibres. I have also taken the liberty to use the terms ven- tral and dorsal for anterior and posterior in some in- stances, and likewise the now almost universally used terms caudal and cephalic for spinalwarts and cere- bralwarts. Editorial additions or comments are in brackets. Joseph Collins. New York, October 15, 1895. REGISTER OF THE PLATE ILLUSTRATIONS. Specification op the Magnification, Staining, Origin, etc., op the Preparations. 1. Morphology of the Central Nervous System. Plate 1. — Brain in situ looked at from above after removal of the bony covering. Revealed by turning the first layer of pasteboard back. Schematic original drawing % natural size. Enlarged from the plan of a drawing by Oestricher. Plate 2. — Horizontal cross section of the cerebrum at the level of the corpus callosum after removal of the latter. The fornix to be turned back. Original drawing % natural size from a fresh brain. Plate 3. — Horizontal cross section of the brain after laying open the third ventricle. On the right the superfices of the central ganglia cut through horizontally. Original drawing % natural size from a fresh brain. Plate 4. — Horizontal cross section of the brain through the cen- tral ganglia (on the left a higher section, on the right a deeper) . The cerebellum is uncoverable. Original drawing % natural size from a fresh brain. Plate 5. — Base of the brain with nerves and blood-vessels. Original drawing % natural size from a fresh brain. Plate 6. — Fig. 1. Base of the cerebrum after removal of brain stem and cerebellum. Schematic original drawing based on a drawing from Ebers taller. ix LIST OP PLATES. Fig. 2. Survey of the projection tracts. Schematic original drawing. Plate 7. — Four frontal sections through the brain of a dog. Fig. 1. Through the frontal lobes. Fig. 2. Through the optic thalamus. Fig. 3. Through the cerebral peduncle. Fig. 4. Through the occipital lobes. Original photographs from fresh cross-sections. Plate 8. — Frontal sections through the human brain stem. Fig. 1. Section through the middle of the third ventricle. Fig. 2. Through the mammillary bodies. Fig. 3. Through the posterior end of the third ventricle. Three original photographs from preparations. Natural size. Plate 9.— Ten frontal sections through the brain stem ; parallel cross sections of the medulla and spinal cord. Fig. 1. Anterior corpora quadrigemina. Fig. 2. Middle of pons. Fig. 3. Middle of fourth ventricle. Fig. 4. Section below 3. Fig. 5. Posterior end of the fourth ventricle Fig. 6. Medulla oblongata below the fourth ventricle. Fig. 7. Pyramidal decussation. Fig. 8. Cross section of cervical cord. Fig. 9. Cross section of dorsal cord. Fig. 10. Cross section of lumbar cord. Original photographs from author's preparations. Natural size. Plate 10. — Cross section of spinal cord in situ. Fig. 1. Cervical cord of a child, with its roots in the spinal canal. Original photograph from personal preparation. Magnified 2>6 diameters. Medullary sheath staining. Fig. 2. Lumbar cord and membranes of a new-born. Original photograph from personal preparation. Magnified 10 diameters. X LIST OF PLATES. 2. Development and Structure of the Nervous System. Plate 11. — Embryonal primary constituent. Fig. 1. Cross section through the medullary grooves (sche- matic) . Fig. 2. Cross section through the medullary channel. Fig. 3. Cross section of the spinal cord at second month (carmine stain) . Fig. 4. Cross section of spinal cord at eighth month (medul- lary sheath stain) . Fig. 5 Peripheral nerve of a new-born (medullary sheath stain). Original drawings (Fig. 1 with the use of an illustration from Merkel. Fig. 2, one from His) from personal prep- arations. Plate 12. — Embryonal development of the brain. Fig. 1. Brain and spinal cord, third month. Fig. 2. Base of brain, fourth month. Fig. 3. Median surface of brain, fourth month. Fig. 4. External surface of the cerebral hemisphere, fifth month. Original drawing. Natural size. Plate 13. — Structure of neurons. Fig. 1. Pyramidal cells (metallic impregnation after Golgi). Fig. 2. Anterior horn cells (stain as above) . Both magni- fied 700 diameters. Fig. 3. Scheme of the construction of the more important tracts and their connections. Original drawings. Plate 14. — Ganglion cells. Fig. 1. a-d, original drawings from preparations with Nissl's stain. X 400. Fig. 2. Purkinje's cells (Cajal's method),. Original photographs. X 250. Plate 15. — Cerebral cortex. Fig. 1. Cortex of frontal lobe. Fig. 2. Cortex of occipital lobe. Original drawings based on an illustration from Edinger. On the left methyl blue stain, on the right medullary sheath stain. LIST OF PLATES. Plate 16. — Brain cortex and meninges. Fig. 1. Scheme of the membranes. Fig. 2. Choroid plexus, x 150, carmine staining. Fig. 3. Photograph of a cerebral convolution (medullary sheath stain) . x 50 diameters. Fig. 4. Cerebellar cortex (combined medullary sheath and methyl blue staining) . x 60 diameters. Original drawings, personal preparations. Plate 17. — Cerebral convolutions. Figs. 1 and 2. Schematic representation of the convolutions on the external and median surface of the hemispheres. Original drawings. Fig. 3. The cortical centres and their location in the skull cavity. Original drawing based on a figure from Vierordt. Plate 18. — Fig. 1. The position of the motor and sensory nuclei in the brain stem and medulla. Schematic original drawings. Fig. 2. a-d, nerve fibre, longitudinal and cross section, a, b, medullary sheath stain, c, freshly isolated, d, nigrosin staining. Plate 19. — Lateral view of the medulla; representation of the nuclei of the cranial nerves. Schematic original drawings based on a representation from Edinger. Plate 20. — The nuclear layer of the motorial peripheral neurons. Fig. 1. Section through the hypoglossal nucleus. Fig. 2. Section through anterior horn of the cervical cord. Original drawing from (combined) preparations stained with carmine medullary sheath stain. X 300 diameters. Plate 21. Fig. 1. Cross section through the -white medullarv substance of the spinal cord (lateral columns). Fig. 2. Section through a spinal ganglion. Fig. 3. Section through a peripheral nerve. Original drawings. Fig. 1, carmine preparation; Fig. 2, carmine and medullary-sheath stain; Fig. 3, nigrosin staining. X 360 diameters. xii LIST OF PLATES. Plate 22. — Fig. 1. Schematic representation of the composition of the cervical and lumbar cord. Fig. 2. Central canal in lumbar region (medullary sheath stain) Original drawings. Fig. 2 X 150 diameters. 3. Topographical Anatomy of the Nervous System. Serial Sections. Schematic. Plate 23. — Division of the brain and spinal-cord nerves. Original drawing with use in part of illustration from Gowers. Plate 24. — Fig. 1. Frontal section through the knee of the cor- pus callosum and the anterior portion of the frontal lobes. Fig. 2. Frontal section through the head of the caudate nucleus. These and all the following original drawings are from preparations made with medullary sheath stains. Natural size. Plate 25. — Fig. 1. Frontal section in the middle of the septum pellucidum. Fig. 2. Section through the anterior commissure. Plate 26. — Fig. 1. Frontal section behind the anterior com- missure. Fig. 2. Section through the knee of the internal capsule. Plate 27. — Fig. 1. Section through the middle commissure. Fig. 2. Section through the central convolutions. Plate 28.— Fig. 1. Section through the parietal lobes. Fig. 2. Section through the parietal lobes. Plate 29. — Fig. 1. Frontal section through the posterior pole of the occipital lobes. Fig. 2. Horizontal section through the superfices of the cor- pus striatum and thalamus opticus. Fig. 3. Horizontal section through the cerebral peduncles. Plate 30. — Horizontal section through the entire left hemisphere in the middle of the central ganglia. Plate 31. — Horizontal section through the base of the brain stem of the left hemisphere. xiii LIST OF PLATES. Plate 32. — Fig. 1. Right angle section through the anterior corpora quadrigemina. Fig. 2. Section between anterior and posterior corpora quad- rigemina. X 1)4 diameters, and the same for the following. Plate 33. — Fig. 1. Section through the posterior corpora quad- rigemina. Fig. 2. Section through the middle of the pons. Plate 34. — Fig. 1. Section through the posterior end of the pons. Fig. 2. Section through the acusticus nuclei. Plate 35. — Fig. 1. Section through the right optic thalamus at the level of the middle commissure. Original photographs from medullary-sheath stain prepara- tions. X tyl tin- body, and taken together they are known as the projection tracts of the cortex. 8 Tab. 6. % / r%.2 Explanation of Plate 7. Frontal Sections through the Brain op a Dog. (Photographs. ) One recognizes without further explanation the central white medullary substance and the convoluted gray cor- tex of the cerebral hemispheres. The medullary sub- stance is, comparatively, much smaller than in man and the convolutions less numerous. Fig. 1. — Section through the Frontal Lobes. It includes the head of the nucleus caudatus which projects into the lateral ventricles. The corpus callosum and the septum pellucidum beneath it are easily recog- nized, as well as the section of the anterior limb of the internal capsule (c.i.). The optic nerve is seen on the base and laterally to it the olfactory lobe (atrophied in man). Fig. 2. — Section through the Optic Thalamus (Th), and the Tail of the Caudate Nucleus. Under the corpus callosum (c. c. ) the fornix (fim- bria). Lateral from the thalamus the internal capsule (posterior limb), which passes downward to the peduncle (optic tract, corpora candicantia, inferior horn of lateral ventricle in temporal lobe) . Fig. 3. — Section through the Cerebral Peduncle. The crusta (Fed.) is liberated from its hemispherical envelopment, above is the tegmental area separated from the former by the substantia nigra. Laterally from this the optic tract ends in the lateral geniculate body (g.l.) and the pulvinar. The third ventricle extends under the posterior commissure as the aqueduct of Sylvius. Fig. 4. — Section through the Occipital Lobes, the Cere- bellum, and the Medulla. In the occipital lobes the posterior horn of the lateral ventricle; under the same, in the middle, the worm of the cerebellum ; laterally therefrom parts of the hemi- spheres. In the medulla cross-section, brachium con- junctivum, floor of the fourth ventricle, fillet area, pyramids, and pons fibres. Explanation of Plate 8. Frontal Sections through the Human Brain Stem. (Photographs. ) Fig. 1. — Section tit rough the Third Ventricle. The corpus callosuin, fornix, and lateral ventricle are recognized at once, likewise the cross section of the cau- date nucleus and beneath it the optic thalamus (ante- rior tubercle). Laterally therefrom the internal capsule (posterior limb). Further outward and below the in- ternal portion of the lenticular nucleus (globus pallidus) and a smaller portion of the outer segment (putamen). The optic tract, the mammillary bodies, the lowest convo- lutions of the temporal lobes (uncus of the hippocampal gyrus), nucleus amygdale (n.a.), and the inferior horn of the lateral ventricle. Fig. 2. — Section Behind 1 through the Mammillary Bodies. Corpus callosum, fornix, thalamus, caudate nucleus, internal capsule (which has in part passed out as pedun- cle), lateral ventricle, third ventricle, hippocampal con- volution, optic tract. To the corpora candicantia there passes a bundle from the thalami. The descending pillars of the fornix end laterally in the corpora candicantia. Fig. 3. — Section through the Posterior End of the Third Ventricle, shortly before its transition to the aqueduct; the subthalamic region lying beneath the optic thalami comes in contact with the other side. Here are the red nucleus, the fillet (lemniscus), and the subthalamic body. The crusta is free, and laterally to it is the lateral geniculate body with the beginning of the optic tract. 1U Fi 9 1 Fig. 2 Fu,3 Tab. 8. Taf. 0. Fig. I. Fin. 3. Fig. 2, Fig. 4. Fig. 6. Fig. Fig. 8. Fig. 9. Fig. 10. Explanation of Plate 9. Frontal Section through the Brain Stem; Par- allel Transverse Sections through the Me- dulla and Spinal Cord. (Photographs.) Fig. 1. — Section through the Anterior Corpora Quadrigemina. Under the corpora quadrigemina (qa) the aqueduct of Syl- vius (A) and laterally to it the medial geniculate body (gm) ; under it the tegmentum of the cerebral peduncles (red nucleus [«;■]), fillet (L), and beneath (substantia nigra) thecrusta. Be- neath the aqueduct lies the motor oculi nucleus. Fig. 2. — Section through the Middle of the Pons. The larger portion of the fibres of the peduncles end partly in the pons, while a part course farther as pyramidal tracts, covered by the transverse fibres of the pons. The brachium conjunctivum passes out of the tegmentum as the lateral wall of the fourth ven- tricle (which results from enlargement of the aqueduct of Syl- vius) to the cerebellum. The roof of the fourth ventricle is formed by the vermis of the cerebellum, and laterally therefrom are the convolutions of the cerebellar hemispheres. Fig. 3. — Section through the Fourth Ventricle at the Posterior End of the Pons. For the boundaries of the ventricle see 2. The brachium con- junctivum has entered the medullary substance of the cerebel- lum. The hemispheres of the cerebellum (Cb) are cut through at their greatest diameter (medullary and cortical substance). The pyramids (Py) pass out free ; caudad therefrom the prin- cipal tegmental region (fillet, facial nucleus, auditory) . Fig. 4. — Section Immediately Behind Fig. 3. The Drocessus cerebelli ad medullam oblongatam (restiform bodies), which in the previous section united cerebellum and medulla, have here passed entirely out of the medullary sub- stance ; within the medullary substance is seen the corpus denta- tum cerebelli (cd); close by the pyramids (Py) are the olives. Uvula (u) of the worm («), nodules (n) (lobes of the cerebellum). Fig. 5. — Section through the Posterior End of the Floor of the Fourth Ventricle (Calamus Scriptorius) . The restiform bodies approach each other. The cerebellum is partly cut away. Fig. 6. — Section through the Nuclei of the Posterior Columns, Passing through the Restiform Bodies (fp). Pyramids (Py), proton of lateral columns (ft) . Fig. 7. — Section at the Level of the Pyramidal Decussation. Each pyramid passes in great part into the lateral column of the opposite side. Figs. 8, 9, 10. — Transverse Section of Cervical Cord, Dorsal Cord, and Lumbar Cord. H-shaped central gray substance (anterior horn, posterior horn) . The anterior, lateral, posterior columns (fa, fl, fp) make up the white substance. 11 Explanation of Plate 10. Transverse Section of the Spinal Cord in Situ. (Photographs.) The usually white medullary substance is here colored black (medullary sheath stain) . See text, Section VI. Fig. 1. — A Child's Cervical Cord with its Roots in the Spinal Canal (Sixth Cervical Vertebra and its Environs) . In the bony capsule within the three membranes lies the cord. The anterior roots (ra) (motorial) spring from the anterior half of the central gray substance (an- terior horn) ; the posterior roots {rp) (sensory) pass out from the posterior horns. Both roots, after uniting, pass out of the spinal canal through the intervertebral foramen (ft) as a peripheral nerve (Np). The pos- terior root forms in the foramen the intervertebral ganglion (spinal) (gi). Body of vertebra (v), spinous process (Pr sp), spinal arch (av). Fig. 2. — Lumbar Cord of a Newborn within its Mem- branes. The outer envelope is the dura (dm) surrounded by Breschet's plexus of veins (Plv), the middle the arachnoid (ar) ; both of these surround the cord loosely. The inner envelope, the pia (put), with the blood-vessels surrounds the cord closely. In the subarachnoidal and subdural space is the cerebro-spinal fluid. The anterior (ra) and posterior (rp) roots pass off from the spinal cord in the lumbar region at a lower level than that at which they arise. They then unite and surround the cord (on deeper transverse sections called the cauda equina) . In the spinal cord the deep anterior longitudinal sul- cus (sa), the shallow posterior longitudinal sulcus, (the anterior columns (fa), the lateral columns (Ji), the posterior columns (fp), in the middle the central canal, (<■<■) (the continuation of the ventricular system), an- terior and posterior commissures between the anterior horn (Ca) and posterior horn (Cp) of the gray (central) substance. 13 Tafel 10. -■# JP & »* riv r II. DEVELOPMENT AND ARCHITEC- TURE OF THE NERVOUS SYSTEM. (Section II. of Textual Part.) 13 Tab. 11. ch.d. end. Fig.1 &*■ Fig. 2 KgM Fig- 5 Explanation of Plate 1 1 . Embryonal Primary Constituent of the Organs. Fig. 1. — Cross Section through the, Medullary Groove. The medullary groove (yellow) originates from the ectoderm; laterally from it is the ganglionic ledge, from the cells of which the intervertebral ganglia develop. Mesoderm (blue), chorda dorsalis (brown), entoderm (red), ectoderm. Fig. 2. — Cross Section through the Medullary Chan- nel (First Month). The stratified epithelial cells of the walls differentiate themselves into spongioblasts (connective-tissue frame- work substance) and neuroblasts (nervous substance proper). From the neuroblasts develop ventrally (an- terior horn proton) the anterior motor roots (ra), dor- sally from the cells of the spinal ganglia (gi) the sen- sory posterior roots grown into the dorsal part of the cord. Fig. 3. — Cross Section of the Spinal Cord (Second Month). Differentiation of the central and peripheral gray sab- stance and later of the white substance. The anterior and posterior horns have formed. The roots as in Fig. 2. Yig. 4. — Cross Section of Spinal Cord (Eighth Month) . Medullation of nerve fibres in the white substance fol- lows successively and systematically. Tracts which are anatomically or functionally in relationship become me- dullated simultaneously. The pyramidal tracts (Py.l. and a.) are the last to get their medullary sheaths. In the figure the fibres that are clothed with medullary sheaths are stained black, the non-medullated are unstained, brownish. Fig. 5.- — Peripheral Nerve of a Newborn. Here likewise the medullation of individual nerve fibres occurs successively, but in its entirety earlier than in the central organs. The medullary proton is here not complete and definite. 15 Explanation of Plate 12. Embryonal Development of the Brain. Fig. 1. — Brain and Spinal Cord at the Third Month. The fore-brain (/) has already separated into the two hemispheres and covers the tween and middle brain (III) (optic thalamus and corpora quadrigemina pro- ton). Behind is the hind-brain (cerebellar proton) (IV) and the after-brain (medulla proton) (V). In the spinal cord the two enlargements (cervical and lum- bar swellings) (J.C. and J. L.). Fig. 2. — Base of the Brain (Fourth Month). The frontal (L.f.) and the temporal lobes (L.t.) are separated by the Sylvian groove. Chiasm (II), cere- bral peduncle (Pe), pons (P) are recognizable. Cere- bellum (Cb), pyramids (Py), olives (o). Fig. 3. — Median Surface of Brain (Fourth Month). Corpus callosum (c.c.) and fornix are clearly recog- nizable ; anteriorly between the two the septum pelluci- dum (S.jj.). The descending pillar of the fornix bends posteriorly and ends in the mammillary body. Fig. 4. — Outer Surface of a Cerebral Hemisphere (Fifth Month). On the surface begins the fissure formation. From above downward is the central sulcus of Rolando. From below the fossa of Sylvius (f.S.), in the depths of which is the proton (J) of the island of Reil. For further reference to medullary sheath proton in the brain see Plate 48. 1G Fig- 1 L.f. I f s L.b. Pe P oPy Cb Cb Tab. 12. Eig.2 Fig- 3 L.o. Fig.k Tab. 13. Fig 2 Fig 3 Explanation of Plate 13. Structure of the Neurons. Every neuron consists of a nerve cell and its prolon- gations, the nerve fibres. The cells as well as the fibres ramify multifariously. Two kinds of ikeurons are differentiated : neurons with a long nerve prolonga- tion (Deiters' type) and neurons with only a short nerve prolongation (Golgi's type). Fig. 1. — A Pyramidal Cell from the Cerebral Cortex with its Tree-like Ramifications (dendrites, protoplasmic prolongations). Each prolongation has numerous bud- like, later twig-like branches. The never fibre of the cell (axis-cylinder prolongation) is designated by a. Its terminal ramification occurs remotely in another part of the brain or of the spinal cord and takes place around the dendrites of ganglion cells there lying (Fig. 2). This neuron has its course and termination entirely in the central organ, and is therefore called central neuron. Fig. 2 represents a ganglion cell with its dendrites from the anterior horn of the spinal cord. Between its ramifications lies the terminal arborization of the nerve fibre of the central neurons. Its nerve fibre (a, axis- cylinder prolongation) after a short course goes out of the central organ and passes peripherally to the soft parts. The entire neuron is therefore called peripheral neuron. Fig. 3 shows the schematic construction of the nerve tracts from such neurons, especially the motorial (cor- tico-muscular tract) is represented above. The central motor neuron (red) splits up around the cells of the peripheral neuron (blue) ; similarly in part is the con- struction of the sensory tract from two neurons. The peripheral sensory neuron (brown) ends with its ter- minal arborization around the cells of the central sensory neurons (green). The fibre arborization in the centrif- ugally conducting motorial neurons occurs in a reverse sense to that of centripetally conducting sensory. These are then the projection tracts. In the cortex are other neurons (green) , which from their manifold connec- tions are called the association tracts. (More in text, Section III.). 17 Explanation of Plate 14. Ganglion Cells. Nerve cells (ganglion cells) are always found col- lected in more or less large groups in certain places called gray substance. They are most numerous in the cortex, the central ganglia (corpus striatum, i.e., cau- date and lenticular nucleus and the optic thalamus), cor- pora quadrigemina, corpora geniculata, in the nuclear layer of the tegmentum, and in the gray substance around the ventricles from the aqueduct of Sylvius on, which substance continued into the spinal cord is known as the anterior and posterior horns. Fig. 1. Only the coarser prolongations of the cells are recognized by this method of staining; in spite of that the cell structure is in these clearer, many having pig- ment. (a) Pyramidal cells of the cerebral cortex. (b) Cells from the anterior horn of the spinal cord. (c) Cells from Goll's and Burdach's nuclei (nuclei of the posterior columns) . (d) Cells from the substantia nigra, strong pigmen- tation. (e) Cells from the corpus striatum, optic thalamus, clau strum. Fig. 2. A cell of Purkinje from the cerebellar cortex. These cells have the richest ramifications of all the gan- glion cells (photograph). The significance of the dendrites is not yet completely understood (whether of purely nervous or nutritive function) . 18 Tab. 14. Fig d. Tab. 15. M i ) A %./ ^2 Explanation of Plate 15. Cerebral Cortex. Fig. 1 shmcs the Cortex of the Frontal Lobe. Fig. 2 that of the Occipital Lobe, Strong Magnification. The left half shows the pyramidal cells, the right half the fibres ; both naturally lie together. The cortex of different convolutions is individually very differ- ently constructed, nevertheless there is certain uniformity in the proton. In the layer of pyramidal cells there can be differentiated an upper, a middle, and an inferior formation. The upper layer has small pyramidal cells ; the middle, large, contiguous, pyram- idal cells. The largest cells are found in the middle layer (es- pecially numerous in the frontal lobes and the central convolu- tions) . In the inferior layer smaller cells are found. The nerve fibres of the cortex come in part from the medullary substance of the hemispheres (5) . These radiate, arranged in tufts, in a straight manner into the cortex, and end somewhat beyond the middle of the cortex (radii). Between these verti- cally passing medullary fibres ramify the remaining cortical fibres, thus forming the tangential fibre network, a part (2, 3) above the radiations, superradiating, a part within the radia- tion, interradiating network. Between both (3) is a thick collec- tion of tangential fibres (Baillarger's, Gennari's, Vic d'Azyr's layer) , which can be seen distinctly in the cortex of the cuneus. Close beneath the pia and very superficially lies (1) a layer of such tangential fibres. In it and beneath it until the first pyram- idal cell layer is reached and also in that are seen small oval cells (not represented) with short ramifications (Golgi's type). All these cells are built on the same principle as the pyramidal cells of Plate 13, Fig. 1. The entire tangential network is in connection with the ramification of the fibres. The medullary radiations are in connection in part in the cortex with the nerve fibres that arise from its cells, and in part with fibres that come from one portion of the cortex and undergo terminal distribution in another, such as the projection and association fibres. See scheme of the cortex, Plate 13, 3, above. 19 Explanation of Plate 16. Brain Cortex and Meninges. Fig. 1. — Scheme of the Meninges. The dura (d) covers over the bony tables of the skull cap, representing the position of the periosteum; beneath is the subdural lymph space. The arachnoid (a) united with the pia (p) lies in close apposition to the brain and passes over the fis- sures like a bridge. Beneath it the multi-compartment subarachnoidal space in communication with the ven- tricular cavity, which forms large spaces (filled with cerebro-spinal fluid) at the base in front of and behind the pons. The Pacchionian bodies (G.P.) are connec- tive-tissue accumulations of the arachnoid. The pia in- ternally lies on the outer layer of. the cortex and sends its blood-vessels in all over the cortical substance; it covers, therefore, the sulci as well. Beneath the brain cortex is the radiating medullary substance. Fig. 2 is a tuft of the choroid plexus, the vascular prolongation of pia in the third ventricle. One recog- nizes the cubical epithelium and the vessel walls. Fig. 3 is a single small cortical convolution from the cerebrum; the radiating black-colored (naturally white substance) medullary substance passes out bush-like (photograph) . Fig. 4 shows the somewhat different architecture of the cortex of the cerebellum compared with the cortex of cerebrum. The medullary substance (black) is smaller. Close to it is the nuclear layer (zona granulosa) of the cortex (blue), on the borders of which are the large cells of Purkinje (see Plate 14, Fig. 2). Their rami- fications form, as well as those of other medullary fibres, the molecular zone of the surface. Then comes the closely apposed pia covering (not represented). A por- tion of the nuclear cells form (not represented) short ramifications of Golgi's type. 20 Tab. 16. Am Fy3 Tab. 17. Fu,1 Fvg.2 fig 3 Explanation of Plate 17. CeEEBRAL Con VOLUTIONS. Figs. 1 and 2 show schematically the convolutions and fissures of the cortex on the external and median surfaces of the hemispheres. One recognizes in the frontal lobe three gyri (gyrus superior, middle, and inferior). These are separated behind from the central convolutions {y. centr. ant. and post.) by the central sulcus. On the median surface the lobus centralis is called the lobus paracentralis. The parietal lobe divides into the upper and lower group of convolutions, the lower being divided into the supra- marginal gyrus, the angular gyrus, and the pre-occipital, and on the median surface the upper appears as the pre- cuneus. In the occipital lobes are the three gyri — ■ superior, middle, and inferior— and on the median sur- face there is found the cuneus and lingula separated by the calcarine fissure. The temporal lobes have likewise three convolutions, the superior, middle, and inferior gyri, and on the median surface the temporo-occipital gyrus borders on the inferior marginal convolution, the gyrus hippocampus (anteriorly the uncus). The upper marginal convolution constitutes the gyrus fornicatus. Fig. 3. — The Position of the Psycho- Motorial and Psycho- Sensorial Cortical Centres in the Skull Cavity. The central representation for motility and sensibility of the periphery of the body is in the cortex of the cere- bral hemispheres. Parts known with certainty to be the seat of such representation are the central convolutions, the inferior frontal and the upper temporal lobes, and the cortex of the occipital lobe (especially its median surface). The apportionment and limitations are given in the figure. BC motor centre for the lower extremites, AC fov the up- per, VIIC for the face musculature, X11C for the hypo- glossal; MSpC motorial, SSjiC, sensorial speech centre, SC centre for vision; 8s, sensory sphere (trigeminus and extremities) . For further, see Section IV. The upper end of the central sulcus (fissure of Rolando) is to be found 5 cm. behind the coronary suture. A sagittal section through the root of the nose and the external protuberance passes somewhat beneath the fossa of Sylvius. With this line the central sulcus forms an angle of about 65°. If the so formed Rolando's line is divided into three parts, the po- sition of the motor centres will be practically determined. 21 Explanation of Plate 18. Fig. 1 shows the position of the motor and sensory nuclei from which the cranial nerves arise or in which they end. They are delineated in the brain stem and medulla as viewed from above. From the blue nuclei arise the motor, from the green the sensory cranial nerves. The cells of the green nuclei form the beginning of the central sensory neurons (compare Plate 13) . The Koman letters indicate the cranial nerves: Vn nasal descending (probably motor), Vc caudal descending root of the trigeminus; Vm, motor, Vs, sensory tri- geminus nucleus; VI1L., cochlear nerve of auditory, VUIv.f vestibular nerve of the auditory. Fig. 2 shows various isolated nerve fibres which col- lectively constitute the white medullary masses of the brain, the columns of the spinal cord, and the per- ipheral nerves, but are found also in the gray sub- stance. The most important part of each nerve fibre is the axis cylinder (cell prolongation). It is sur- rounded by a medullary envelope of varying thick- ness, the white medullary sheath which is put on in segments around this. Within the peripheral nerves around this is the thin sheath of Schwann. (a) Longitudinally running medullated nerve fibres, the medullated substance stained black and covering the axis cylinder. This is seen better on transverse section (h) and in the other fibres (c) and (<1). The axis cylin- der is made up of numerous individual fibrillse. 22 Tab. 18. Fig.1 Fuj2 jo a" tC Explanation of Plate 19. Lateral View of the Medulla Oblongata with the Schematic Representation of the Nuclei and the Intramedullary Course of the Cranial Nerves. The uppermost nerve is the motor oculi (111). Its nucleus, of long extent and consisting of several parts, lies in the central gray matter of the ventricle beneath the aqueduct of Sylvius. Behind it lies the nucleus of the trochlear nerve ; the nerve (IV) passes dorsally as one of the cranial nerves out behind the pos- terior quadrigeminal bodies, decussates with its fellow of the other side, and then passes to the base. The trigeminus ( V) arises in two portions ; the anterior mo- torial ( Vm) arises from the motor ( V) nucleus, to it is joined the probably motorial nasal descending root (rn), which arises laterally from the aqueduct (here represented as sensory root) . The posterior sensory ( Vs) originates from the Gasserian gan- glion and separates in the pons in three portions : one portion ends in the sensory vagus nucleus ; a second portion passes as the caudal ascending root (re) through the medulla as far as the first cervical segment, Where it ends by degrees ; a third portion passes to the cerebellum. The facial ( VII) arises from its ex- tensive and deeply situated nucleus in the medulla, gathers itself together to the knee of the facial, passes around the adducens nucleus (VI) with an outward curvature, and finally emerges beneath it. The course of the abducens is simple. The audi- tory (VIII) ends as the cochlear nerve (Vlllc.) in the ventral nucleus, and as vestibular nerve ( VIlv) in the dorsal nucleus and its environs ; one portion passes as descending root of the VIII, a short distance further toward the spinal cord (not represented) . The sensory glossopharyngeal-vagus fibres come out from the petrosal and jugular ganglia and end in the sensory IX and X nuclei in the posterior end of the calamus scriptorius (X, green) ; a portion passes as descending root of the X some distance toward the spinal cord (solitary fascicle). The motor fibres arise in part from the nucleus ambiguus (X, blue), and in part from the spinal accessory nucleus. The hypoglossal (XII) nucleus lies in the caudal dorsal seg- ment of the medulla and sends its fibres out through the medulla laterally to the pyramids. The nucleus of the spinal acces- sory (XI) reaches far down in the upper cervical cord and its fibres pass out through the lateral columns ; r.p— posterior, upper cerviacl root from the spinal ganglia, r.a=anterior upper cervical roots. 23 Explanation of Plate 20. The Nuclear Layer of the Peripheral Motor Neurons. Fig. 1 shows a segment from the anterior gray horn of the cervical cord with its motor ganglion cells. From these cells the roots of the anterior motor nerves origin- ate (ra), which pass through the adjoining white sub- stance of the antero-lateral columns (the medullated nerve fibres stained black on transverse section). The medullated fibres which are woven around the cells subserve in part the transportation of reflexes (re- flex collaterals from the posterior roots) . Fig. 2 represents a part of the hypoglossal nucleus. The numerous large multipolar cells give rise to the fibres of the hypoglossal nerve. Coursing around the cells are innumerable medullated nerve fibres of varying diameter which form a fine network. These fibres are in part central tracts, and in part unite the nuclei of the two sides, especially the inner parts (in this way the unison of action of both halves of the tongue is ex- plained) and thus serve for transmission of the reflexes. In an entirely similar way the facial, the motor oculi, etc., nuclei are constructed. In these two territories, therefore, begins the periphe- ral motor neuron, while simultaneously the terminal ramifications (the latter are not perceptible with this staining) of the central neuron take place about these cells. 24 Tab. 20. Fig.1 Fy2 Tab. 21. .. V' >.* ■• I. u Fig.1 #9-2 ag.3 Explanation of Plate 21. Fig. 1. — Transverse Section through the White Medul- lary Substance of the Spinal Cord {Lateral Column). The medullary substance consists of the closely woven medullated nerve fibres which are embedded in the framework of glia. As the preponderating number of nerve fibres course longitudinally it follows that on cross section we see mostly the fibres cut across (sun images). In the centre of each fibre is the axis cyl- inder. Fig. 2. — Section through a Spinal Ganglion. The strongly pigmented cells of the ganglion (like- wise, for instance, the Gasserian ganglion) are sur- rounded by outgoing and incoming sensory nerve fibres, the outgoing fibres forming the posterior root. A fibre passes into each cell and out again (T formation). These cells are the places of origin of the peripheral sensory neurons. Fig. 3. — Section through a Peripheral Nerve. Every nerve is made up of several bundles. The en- tire nerve is surrounded by a connective-tissue envelope, the epineurium. The bundles lie in the several com- partments of the perineurium. The epineurium sepa- rates the individual nerve bundles into sections. In these lie first the medullated nerve fibre surrounded by the sheath of Schwann in fibrillae sheaths. Blood-ves- sels and lymph vessels ramify in the perineurium. In reality the nerves in transverse section are much closer together than they are represented here. One should remark the different thickness of the fibres. 25 Explanation of Plate 22. Fig. 1. — Schematic Representation of the Composition of the Cervical Cord on the Left, of the Lumbar Cord on the Right. Between the anterior fissure (sulcus anterior, S.a) and the anterior roots (r.a.) lies the anterior column. It consists of the anterior uncrossed pyramidal column (pyramidal tract, Pya) and the anterior ground bundle (fa.). Between the anterior and posterior roots (rp) lies the lateral column. It is divided into the column of Gowers (G), the lateral pyramidal tract (Cb), the crossed pyramidal tract of the lateral column (Py), the lateral ground bundle (fal) (ground bundle of the lateral columns), and the lateral limiting layer (f). The posterior columns are divided into the columns of Goll (G) and the columns of Burdach (B). In the pos- tero-lateral portion of the latter the posterior roots enter (the posterior root zone). At the apex of the poste- rior horn Lissauer's column is situated (L) (medullary bridge); z. r. = postero-external, v. =the ventral field of the posterior columns. The gray substance is divided into the anterior (C.a.) and the posterior (C.p.) horns; between them in the middle line lie Clarke's columns (CI). In front of the central canal (c.c.) lies the anterior white commissure (C.a.), and behind the same the poste- rior gray commissure. The ganglionic cells of the ante- rior horns are divided into a lateral and a medial group, each of which is further divided into an anterior and posterior portion. In the base of the posterior horn is the substantia gelatinosa (S.g.); contiguous with this is the zona spongiosa, and with the latter the above-men- tioned white medullary bridge. Fig. 2. — The Central Canal and its Environments; St nniy Ma (/ ii if ration. The canal is lined with cylindrical epithelium. One recognizes the medullated fibres of the anterior and pos- terior commissures. Tab. 22. Cerv. Fig.1 Lumb. III. TOPOGRAPHICAL ANATOMY OF THE NERVOUS SYSTEM. (Plates 23-48.) Plates 49-52 schematic representation of the course of the fibres. (Section III. of the Text.) 27 Serial Sections through the Central Nervous System. Plates 24 to 45 are from frontal sections, plates 29-31 from horizontal sections : first through the entire left hemi- sphere, then through the brain stem, the medulla, and the spinal cord. The sections are prepared ■with medullary sheath stains ; in part photographed, in part drawn, and are in no way schematic. As the sections follow one another from the frontal re- gion they represent in their continuity the continuation of the brain stem. In all the sections the me- dullary substance is stained black, while the brain cortex ' is red, the subcortical gan- L#.i glia and nuclear layers are stained blue. The amount of blue stippling will give one an idea as to the richness of cells. Where it is not otherwise stated the drawings are of natural size. One is able to reconstruct the relationship by compari- sons with the previous and following section and to ori- entate himself by referring to the adjoining plan of ~?.a division. Remark.— The brain sections are from a boy sixteen years old. It must be remembered that in the fully developed adult the area of medullary substance is more developed in size and in detail. 31 (la.) interior eye muscles (intercalation of the ciliary ganglion), ciliary muscle for accommoda- ! w mK,IIUi ti on -sphincter of the pupil tor contraction of the pupil. l> ■! (bi exterior eye muscles; levator palpebral supenons; rectus superior, internal, inferior- inferior oblique, movement of the eyeballs upward, inward, and downward. 2 Superior oblique of the eye (movement downward and outward). 3 Muscles of mastication; masseter, temporal, pterygoid, mylo-hyoid— ant. digastric, tensor tympani, tensor and levator veli palati. Secretion of tears ? 4. External rectus of the eye (outward movement). 6 The mimic face muscles; frontal, orbicular of the eye and mouth; zygomatics mental; platyama. Of the ears, stapedius, posterior digastric, etc. Nasal secretions. Tear secretion? Palate musculature i . 6 Throat musculature (constrictors), cnco-thyroid, secretion of gastric juice. Movements of 7 Tongue musculature, sterno-hyoid, thyreoidei. [heart and breathing. 8 Larynx musculature (voice formation), palate, pharyngeal musculature (with the vagus) (act of smallowing)— sterno-cleido-mastoid (drawing the head laterally and nodding). Trape- zius (in part) (shrugging the shoulders). [head). 9. Posterior superficial arid deep head and neck muscles (elevating and lateral movements of 10. Deep posterior and anterior back muscles. Trapezius in part (movement of head and throat). •11. Scaleni (elevators of the ribs, breathing), longus colli. /12. Diaphragm (breathing). ^13. Deep neck muscles. At. Pectoralis major (anterior adduction of the upper arm), pectoralis minor, subclavius. /15. Levator scapuhe, rhomboids (dorsal nerves of the scapula) (draws the scapula inward and up- ward), serratus anticus major (long thoracic nerve) fixes the shoulder blade and draws the same in conjunction with the arm above the horizontal. —18. Supraspinatus (raises and rolls the arm outward), infraspinatus, teres minor (rolls outward). —17. Subscapulars, teres major (rotates inward), latissinius dorsi (adducts the arm and draws it —-18. Deltoid (raises the arm to horizontal.) [backward). /19. Biceps (flexor of forearm and supinator), brachialis anticus (flexor of forearm), coraco- brachial. /W. Flexor communis digitorum (radial portion) (bends the terminal phalanges), flexor longus poi- nds (end phalanx), flexor carpi radialis, pronator radii teres, and quadratus, palmaris longus, thenar muscles (opponents of thumb flex the primary phalanges and extend the terminal pha- langes), luuibricales 1, 2, seldom 3 (flex the peripheral phalanges and extend simultaneously the terminal phalanges). Triceps (extensor of forearm), radial portion of brachialis anticus, supinator longusl (flexes and pronates the forearm), extensor communis digitorum (extensor of the peripheral phalan- ges), entensor pollicis— abductor pollicis, supinator brevis, extensor carpi radialis and ulnaris. Flexor profundus digitorum (ulnar portion), see 20. Flexor carpi ulnaris, hypothenar, inter- ossei (flex the peripheral phalanx), lumbricales (3 and 4), see 20, adductor pollicis. 23. Deep back muscles. 24. Intercostal muBcles. 25. Deep back muscles (extensor of trunk). 26. Intercostal muscles. 27. Back muscles. 28. Intercostal muscles, abdominal muscles (rectus, external oblique) (compressor of abdomen). 29. Back (lumbar) muscles. 30. Transverse abdominal, internal oblique (compressor of abdomen). 31. Cremaster, transverse, oblique. 32. External obturator, adductor of thigh, gracilis (adductor). ^22. 33. % tends [lnfle'!' 13 , le ?"^' iliacus internus (draws up the thigh, flexes the trunk), quadriceps (ex- inVemus^abdu ' t minimus (abductors of thigh), tensor vagina; femoris, pyriformis, obturator Gluteus maximus (extends the thigh), ductor)' ; '"'^P 8 ' semit endlnosus, semimembranosus (flex the leg), quadriceps femoris (ad- digiUcommunii™' 868 * he " mer border of foot )' Peronei (raise outer border of toot), extensor Gastrocnemius, soleus (plantar flexion of the toot), flexor digiti, tibialis posticus. = 40. [Small muscles of foot (flexor brevis, interossei, etc.). Levator, internal sphincter ani, sphincter vesicas. Sphincter ani, perineal musculature, bulbi cavernosa, etc. External sphincter ani. 29 Explanation of Plate 23. Division of the Brain and Spinal Coed Nerves. One is able to recognize the level of a brain or spinal cord segment by the individual nerve roots which come from it. An exact representation of the segments of the brain stem and of the spinal cord are given in the text (Fig. 6- page 48) . Of greatest importance is the rela- tion of an individual segment of the spinal cord to the spinal column (spinous prolongations) and a knowledge of the point of exit of the spinal nerves. The nerves of the lumbar .cord pass far below the segments from which they have their origin before they make their exit. This knowledge and a knowledge of plexus formation is presupposed. The segments are represented in red ; the motor nerves are blue, and the sensory after their exit from the plexuses are brown. In the same way the color of the lettering is represented. The further divisions of the sensory cutaneous nerves are given pictorially and more lucidly than by written description, in Figs. 10, 11, 12, text p. 102 and the following. The motorial nerves (the most important) are num- bered, and there is also a table setting forth the muscles that are innervated by these nerves and such essentials of their function as is carried by their names. Tab. 24. Tab. 25. Explanation of Plate 25. Fig. 1. — Frontal Section through the Middle of the Septum Pellucidum. In addition to the frontal lobes the apex of the tem- poral lobes (l.t.) is cut through. In the medullary sub- stance the ganglion of the brain stem (corpus striatum) on account of the forward projection of the putamen (L) (the outer segment of the lenticular nucleus) is en- tirely involved. The anterior limb of the internal cap- sule breaks through the corpus striatum and thus divides it into the nucleus caudatus (n.c.) lying medially, and the nucleus lenticularis (L) lying laterally. Externally from the putamen is the external capsule (e.e.), and ex- ternally to this may be seen the claustrum (CI). Sep- tum pellucidum (S.p.), olfactory bulb (/) lateral ven- tricle (v. I.), corpus callosum (e.e.). Fig. 2. — Section through the Anterior Commissure. The ascending pillar of the fornix can be seen (/) passing up. The inner portion of the lenticular nucleus (gl.p), the globus pallidus, is likewise apparent. On the base the chiasm of the optic nerve (Ch) can be seen cut through laterally to the perforate substance, then the trigonum olfactorium (/ instead of II) . In the depth of the Sylvian fossa f.s. the anterior convolutions of the island of Reil (Ins) are included laterally to the claustrum. In the anterior portion of the temporal lobes begins the nucleus amygdalae (N. am.) ; see following sections. The cortical convolutions have been cut away. Anterior commissure (c. ant.). The third ventricle begins between the pillars of the fornix. 33 Explanation of Plate 26. Fig. 1. — Frontal Section through the Anterior Com- missure. The descending pillars of the fornix (f.d.) pass back- ward to the mainmillary body at the base. The body of the fornix continues beneath the corpus callosurn, see Fig. 2. Between the adjacent cut-through portions of the thalamus (anterior nucleus) the third ventricle spreads out (o.lll). The globus pallidus (gl-p.) is seen to be made up of several segments and to surround with its basal fibres the internal capsule. From the chiasm the optic tracts (tr.o) pass backward to the lateral geniculate bodies. The anterior horn of the lateral ventricle (c.a) arches backward and is involved in the section which has been cut obliquely. Fig. 2. — Section through the Knee of the Internal Capsule. Beneath the posterior portion of the superior frontal convolutions are the central convolutions (g.c.a. and p.), and in the depths of the fossa of Sylvius the convo- lutions of the island of Reil are included. In the tem- poral convolutions the nucleus amygdalae (N.a.) is in- cluded in the sections. Medially is the cornu ammonis (cam.), the inner vaulting of the hippocampal gyrus. Between the caudate nucleus and the optic thalamus are the stria cornea. Around and through the internal capsule (C.ip.) the ansa lenticularis (L.s.) winds, passing from the globus pallidus. A portion of its fibres unite and pass further dorsally beneath the territory of the thala- mus to the fillet area (upper fillet). In the thalamus (TV/.) the lower stalk of the thalamus passes from the temporal lobes beneath the ansa lenticu- laris. The thalamus has become very much larger and projects upward (tuberculum ant.) as far as the pillar of the fornix, and in it one recognizes different fibre path- ways (laminse medullares). Tuber cinereum (Inf.) 34 Tab. 26. Explanation of Plate 28. Fig. 1. — Section through the Parietal Lobe (ante- rior portion). The brain stem passes farther and farther out from the hemisphere. The peduncle {Fed.) is entirely free; the thalamus (pulvinar) is connected only by its upper and posterior stalk. Between the peduncle and the internal capsule (posterior segment) the lateral genicu- late body (c.g.l.) (in which the optic tract ends) and the medial geniculate body (c.g.m.) have pushed them- selves in. The inferior horn of the ventricle (v.i.) has opened out and one easily recognizes the condition of it produced by the rolling in of the hippocampal gyrus, from the free border of which the fimbria (/) passes up- ward. Laterally from the lateral geniculate bodies the optic radiation (S ) passes through the posterior limb of the internal capsule toward the cortex of the occipital lobes. From the vicinity of the subthalamic region the most important part of the tegmental area has its origin, the subthalamic body has disappeared, the fillet (S) has broadened out, the red nucleus (n.r.) has become larger. The third ventricle passes beneath the posterior commis- sure {p.p.) into the aqueduct of Sylvius (A.S.). The medial peduncular fibres are covered over by the most anterior of the transverse pontal fibres (P) . Posterior insular convolution, lenticular nucleus disappeared; pineal gland (c). Fig. 2. — Section through the Parietal Lobe (poste- rior portion) . The brain stein with the pulvinar has completely sepa- rated itself from the hemisphere. The picture is similar to the first cross-section through the frontal lobe. Corpus callosum (e.c), posterior horn of the lateral ventricle ("./>.), association bundle (/''//., Fare), the optic radiation (G. 0.) passes from the primary optic centres (corp. genie, lat., corp. quadrigem. anterior, pulvinar) farther in the occipital lobes. Parietal convolutions, gyrus angularis [g.ang.), cal- carine fissure (f.c), supramarginal gyrus (g.smg.), lin- gula(2/./.), cuneus (own). 86 30 X> as H Tab. 29 Explanation of Plate 29. Fig. 1. — -Frontal Section through the Posterior Pole of the Occipital Lobe. In the cortex of the cuneus, Vic d'Acyr's bundle. The optic radiation passes entirely into the cortex. Cal- carine fissure (/•('•), lingual lobe {L.I.), cuneus (Curt), Occipital convolutions. Fig. 2. — Horizontal Section through the Superfices of the Corpus Striatum and the Optic Thalamus (some- what higher than in Plate 3, right half) . The internal capsule lies with broad bundles laterally to the cross section of the nucleus caudatus (n.c.) and thalamus opticus (Th). Somewhat externally is the lenticular nucleus (L), claustrum (CI), and cortex of the island. Medially the lateral ventricle (v.l.) is opened, the fornix and corpus callosum (C.c) are cut through. The anterior and posterior radiations of the corpus callosum (forceps anterior and posterior) are to be seen. Fig. 3. — Horizontal Section through the Cerebral Peduncle (somewhat deeper than the section in Plate 4, right half). The section illustrates well the position of the internal capsule which is soon to pass into the pes pedunculi (Pd) with the lenticular nucleus (L.,gl.p.). The subthalamic region and the posterior corpora quadri- gemina (e.qp.) are cut through. Laterally from the corpora quadrigemina the lateral geniculate bodies are included {eg. I. and?/*.). Optic tract {II), anterior com- missure {c.a), trochlear nerve {N.IV), fillet, superior {Ls), inferior {Li), red nucleus {n.r.), subthalamic body (c.sth), substantia nigra (S.?i.), motor oculi (III). 37 Explanation of Plate 30. Horizontal Section through the Entire Left Hemisphere in the Middle of the Central Ganglia. The internal capsule (c.i.) is included in its entire ex- tent; one sees easily the anterior (c.i. a.) and the pos- terior (c.i.p.) limbs, the knee, and behind, the optic radiations of Gratiolet (6r). Medially to it the caudate nucleus (n.c.) and optic thalamus, laterally the lenticular nucleus (Put.), capsula externa (c.e.), claustrum (cl). Tail of the nucleus cau- datus in the posterior horn (est.). Frontal lobes (l-fr.), central convolutions (g.c), isl- and of E-eil (fossa of Sylvius, f.S.), temporo-occipital lobes (I.jj. and l.o.). The corpus callosum (c.e.) is cut through anteriorly and posteriorly, between which lie the septum pelluci- dum (s-2>.), fornix (/), behind the choroid plexus {pi. ch.) covering the third ventricle, anterior horn (c.a.), inferior horn (c.i.) of the ventricle. 33 Tab. 30. Tab 31, L.t Explanation of Plate 3 1 . Horizontal Section through the Base of the Brain Stem of the Left Hemisphere. (About the same level as the section in Plate 4, right.) Both limbs of the internal capsule are included in the section (c.i.a, anterior limb of the caspule) ; the posterior limb forms the principal portion of the crusta (Peel) . The nucleus caudatus (est) and the base of the thalamus are cut across, in the subthalamic region the lenticular nu- cleus passes between the anterior fibres of the peduncle (Pd. ) through the ansa lentiformis (a./.), from the globus pallidus (gl.p.), and laterally therefrom its puta- men (L). Subthalamic body (c.sth.). Substantia nigra (S.h.), lateral geniculate body (II), tail of caudate nucleus (est). Nuclear region of the motor oculi (N.II1), fillet (L.s.), red nucleus (n.r.), anterior horn (c.a.), inferior horn (c.i.) of the lateral ventricle, frontal lobes (L.fr.), island, temporal lobes (L.t.), cor- pus callosum (c.c), descending fornix (f.d.), septum pellucidum (&.p). Claustrum (CI), external capsule (c.e.). 39 Explanation of Plate 32. Fig. 1. — Vertical Section through the Anterior Corpora Quad- rigemina. (Closely following that of Plate 28, 1.) The thalami (Th.o.) (pulvinar) are pressed back and outward from one another by the anterior corpora quadrigemina (e.g. a. ) which press forward between them. The splenium corpus cal- losi (c.c.) with the fornix (/) lies over the anterior corpora quadrigemina. In the central gray matter (C.E.) is the aqueduct of Sylvius (A), and beneath it the nucleus of the motor oculi nerve (III) (peripheral neuron), laterally from it the nasal [descending] root of the fifth (Vn). In the corpora quadrigemina one differentiates a superficial and a deep medullary substance. Beneath these follow the tegmen- tum with the red nucleus (n.r.) of either side which gradually "get closer to oue another, laterally the superior (sensory) fillet (Ls), which includes externally the inferior (of the corpora quad- rigemina) fillet {Li). Laterally to this the median geniculate body (c.g.m.). Separated from the tegmentum by the substan- tia nigra (S.n.) is the crusta (peduncle), and in its middle terri tory are the (motorial) pyramids. The optic tract (Tr.o) passes into the lateral geniculate body, the anterior [superior] quadri- geminal body, the pulvinar and there ends. From there the fibres of the optic radiation pass farther centrally (in the occipi- tal lobes) . (Further details in photographic Plate 35, 2.) Fig. 2. — Section between the Anterior and Posterior Corpora Quittlrigemina. The tegmental area lias completely separated from the pulvi- nar thalami. The fillet (L) passes more caudally beneath the red nucleus. From the deep medullary substance (st.i. ) the fountain-like tegmental radiation (FF) passes to the middle line where it undergoes decussation (raphe). Close beneath the motor oculi nucleus (n.lll) in the central gray matter lies the posterior longitudinal bundle which is here very clearly recog- nizable (fasciculus long, post.) (/) laterally from which the thalamus fibres pass farther (substantia reticularis). In the motor oculi nucleus are readily recognized many individual nuclei. In the posterior braohi'um (Br. a) fibres pass from the posterior quadngeminate body to the lateral geniculate body. In the substantia nigra fibres from the basal ganglion end. 40 Tab. 32. st.s. Fur'2 Tab. 33. Ftg.'l Fig 2 Explanation of Plate 33. Fig. 1. — Section through the Posterior Corpora Quadrigemina. The section includes basally the anterior portion of the pons which covers over tlie crusta. To the posterior corpora quadri- gemina (C.q.p) passes a portion of the inferior (lateral) fillet (Li) . Close to the nasal (descending) trigeminus root ( Vn) the trunk of the trochlear nerve which originates here is involved (IV). In the tegmentum lie the fibres of the hrachium con- junctivum, which originate in the red nucleus and decussate (D.B.) behind it (which pass to the cerebellum as the processus cerebelli ad corpora quadrigemina) . At the side of the posterior longitudinal bundle (/) is the retic- ulated substance of the tegmentum. Beneath the decussation of the hrachium conjunctivum lies the horizontally placed upper (cortex-thalamus) fillet (Ls) (central sensory tract) , and later- ally to it the inferior (corpora quadrigemina) fillet (Li) (cen- tral acoustic tract) . One observes the enormous pontine ganglia (Pg) in which the larger part of the peduncular fibres (medial and lateral parts) end. Fig. 2. — Section through the Middle of the Pons. The aqueduct has widened into the fourth ventricle. Its roof is here formed by the velum medullare anticum (v.m.a.) with the lingula (L) (from the vermis of the cerebellum), laterally the enormous brachium conjunctivum (B) which have completed their decussation. In the tegmental territory are : the posterior longitudinal fasciculus (/), substantia reticularis tegmenti lat- eral from the raphe (R), central tegmental tract (c.t.), superior (medial) and inferior (lateral) fillet (Ls and i). Between the fibre tracts a number of cells are embedded (superior olive [01. s]. nucleus of the substantia reticularis, etc.). Laterally from the tegmentum are the motor (m) and sensory (s) nuclei of the fifth and their roots to which the nasal root of the fifth (Yn) (in its vicinity the pigmented cells of the. locus cceruleus) descends (motorial?) ; an additional tract follows from the neighboring medullary substance of the cerebellum as direct sensory cerebel- lar tract. Downward passes the caudal root of the fifth ( Vc) . The pyramids (Py) pass (from the peduncles) covered over by the superficial and deep pontine fibres through the pons. From the cerebellar cortex comes the processus cerebelli ad pontem (Pr.a.p.). 41 Explanation of Plate 34. Fig. 1. — Section through the Posterior End of the Pons. The facial (n. VII ) and the abducens nuclei (n. VI ) have made their appearance in the tegmentum. The fibres of the facial ( VII ) pass as indicated on the right, arch around the abducens nucleus, collect at the knee (g), and then pass horizontally and eventually basalward out of the medulla ( VII ) . The course of the abducens (VI) is more simple. Its nucleus is clearly in connection with the superior olive. Substantia reticularis (Srt), fillet (Ls), etc., as be- fore. Laterally from the trunk of the facial passes the caudal (descending) trigeminus root (V.c.) which has now made its appearance, with the sensory root of the fifth. To the outside of these the processus cerebelli ad pontem passes downward (Pr.a.]?.), and between this and the brachium conjunctivum lie the restiform bodies (s.C) (process, cerebelli ad medull. oblong.) which can be seen more distinctly in the following section. Fig. 2. — Section through the Auditory Nucleus. In the medullary substance of the cerebellum is the corpus dentatum (C.d.), in the medullary substance of the vermis (V) and other lobes the nucleus tegmenti (n.t). Medially from the flocculus (Fl) of the cere- bellum the acusticus ( VIII ) passes in. Its cochlear branch (VIII. c) ends in the ventral acoustic nucleus (n. VIII. c.) laterally to the restiform body (c.r.) (sche- matic on the right). Its vestibular branch (n.VIII.v.) ends in the dorsal acoustic nucleus (n. VIILd.) and in the nucleus of Deiters just lateral to it {n.D.) (con- tinuation of the locus coeruleus). From the central nucleus of the eighth the corpus trapezoides (c.tr.) passes transversely through the medial fillet (L.s.) (also to the superior olive) to the lateral fillet of the other side. Another portion of the (central) acoustic tract passes in the striae acoustical (str.a.) (schematic on right) to the same place. The pyramids (Py) have passed from out the pons. (From here on the illustrations are photographs.) 42 Tab. 34. Fzg1 JTiff-2 Tafel 35. Fig. 1. Fig. 2. Explanation of Plate 35. Fig. 1. — Section through the Eight Optic Thalamus at the Level of the Middle Commissure. (Sloping somewhat obliquely posteriorly.) The three nuclei of the thalamus are easily recognized (nucleus anterior [a], medial [w], and lateral [/]). From the anterior there passes at this level a thick bun- dle (which in the horizontal section, Plate 31, is cut transversely [r] [Vic d'Azyr's bundle]) which ends in the corpus candicans of the same side (its course into the latter is well shown in the unstained section, Fig. 2, Plate 8). Beneath the thalamus lies the subthalamic region with the ansa lenticularis (Anl), Luys' body (cL), the fibres of which penetrate the internal capsule transversely and go to the globus pallidus (glp) of the lenticular nucleus; beneath the substantia nigra (Sn). In the lateral nucleus (trellis layer) the corona radiata passes out of the internal capsule (e i) into the thala- mus. The middle commissure (cm) contains but few nerve fibres. The medial nucleus forms posteriorly the pulvinar, in which ramify the fibres from the optic tract and the optic radiation (for other illustrations see Plate 27). Fig. 2. — Section through the Anterior Corpora Quad- rigemina of the Left Side. One recognizes the more detailed abundance of fibres than in Plate 32, 1. The lettering is the same as in that figure. In the lateral geniculate body (cgl) and also in the anterior corpora quadrigemina (cqa) end the innumer- able arborizations of the fibres of the optic nerve. In this vicinity the tract for the pupillary reflex must be sought (from here to the oculomotorius nucleus, N1II). Beneath the multitude of outgoing motor oculi fibres (III) begins the crusta (Ped) in the medial segment of which can be seen Spitzka's bundle ($) (which contains probably the central tract for the motor cranial nerves) passing from the crusta up to the tegmentum and later decussating in the median line. 43 Explanation of Plate 36. Fig. 1. — Section through the Tegmentum behind the Posterior Corpora Quadrigemina. The aqueduct has already begun to expand into the fourth (oIV) ventricle. For lettering see Fig. 2, Plate 33. One observes especially the structure of the substantia reticularis (Srt) which conducts fibres from the optic thalamus downward and which contains ascending fibres from the anterior lateral columns of the spinal cord. Further than this very little is known. The median (upper) fillet (Ls) (principal fillet) is divided into sev- eral bundles; laterally is the inferior fillet (Li), which in part passes up to the posterior corpora quadrigemina. Brachium conjunctivum (B), nasal root (Vn), nasal fasciculus of the trigeminus root (Vn), posterior longi- tudinal fasciculus (/) ; the innumerable fibre crossings in the raphe of the tegmentum is clearly represented (the central decussating sensory and the motor tracts pass here), locus coeruleus (I.e.), with strongly pigmented cells. Fig. 2. — Section through the Region of the Trigeminus Nucleus. The section contains practically the same structures as Fig. 2, Plate 33. The lettering is also the same. One observes the finer details of the tegmentum and of the nucleus of the fifth. The caudal (descending) root with its bundles ( Vc) is to be seen in this section very clearly between the motor (m) and sensory (s) nucleus. Central tegmental tract (ct), reticulated sub- stance of the tegment (Srt) ; pons ganglia (g) between the superficial (*) and the deep (p) fibres of the pons (/'). The raphe of the tegmentum (A') and the fibres of the pons contain numerous decussating pathways. Below the superior olive (os) fibres (Li) of the cor- pufl trapezoidea and tin; inferior fi 1 let (central auditory tract) . 44 Taf. 3G. Fig. 1. Fig. 2. >; v v ,:^p;^wl Taf. 37. Fig.l. Fig. 'J Explanation of Plate 37. Fig. 1. — Section through the Might Tegmental Region at the Level of the Facial Nucleus. One should compare the lettering with Fig. 1, Plate 34. From the deeply lying facial nucleus (n. VII ) the individual fibres pass upward. Likewise the pathway from the superior olive (ol.s.) to the abducens nucleus (NVI, white), (which last was more clearly recognizable somewhat further forward) is to be seen. From the cerebellum pass the restiform body (Or) and the processus cerebelli ad pontem (Cb). From the genu facialis (gVII) passes the united trunk of the seventh over the ependyma of the fourth ventricle (vIV). To the fillet passes from the neigh- boring ventral acoustic nucleus the corpus trapezoides (through the inner fillet). Lateral from the trunk of the facial lies the descend- ing root of the fifth ( Vc), immediately in front of the substantia gelatinosa (Sg), which is the continuation up- ward of the posterior horns of the spinal cord. Dor- sally therefrom is the dorsal nucleus of the eighth (nVIIl) and the nucleus of Deiters (n.D.); superior, inferior fillet (Ls.i.); substantia reticularis {Srt)\ central tegmental tract (ct) ; raphe (K). Fig. 2. — Section through the Ventral Acoustic Nucleus of the Left Side. The restiform body (cr) has passed entirely out of the cerebellum and helps to form the lateral wall of the fourth ventricle. Laterally from it lies the semicircu- lar ventral auditory nucleus in which the cochlear nerve goes. This is more developed in Fig. 2, Plate 34. From its central tract the black-colored fibres of the striae acusticse (stra), which can be distinctly seen here, pass over the floor of the fourth ventricle to the median line. They cross on the raphe (B) and pass farther for- ward in the lateral fillet. Dorsal nucleus of the eighth (nVIIId), medially therefrom the nuclear region of the glossopharyngeal (nIX), facial nucleus (nVIl), sub- stantia reticularis (Srt), central tegmental tract (ct), median fillet (L), pyramid, posterior longitudinal fas- ciculus (/), flocculus of the cerebellum (fi), descending acousticus root (ad). 45 Explanation of Plate 38. Fig. 1. — Section through the Cerebellum and Medulla. (Posterior portion of the Fourth Ventricle. ) The fourth, ventricle (vIV) is here closed laterally- only by the meninges as the restiform bodies (cr) have entirely passed out of the cerebellar hemispheres. The roof of the ventricle is formed by the vermis (V), the superior vermis (vs), the inferior vermis (vi). In the cerebellum the corpus dentatum (cd) and the nucleus tegmenti (nt). The borders of the hemisphere are cut away. Nodulus (n). In the medulla one recognizes the pyramids, the olives, the restiform bodies, etc. Fig. 2. — Section through the Medulla at the Level of the Glosso-Pharyngeal — Vagus Nucletis. Laterally from the pyramids the inferior olives (ol) have made their appearance. From the restiform bodies (cr) pass the cerebellar fibres (fol), decussating to the olive of the other side. Between the olives near the raphe (K ) is represented the " interolivary layer" of the (superior) fillet (L) ; dorsally to it passes the posterior longitudinal bundle (/) . Between the posterior longi- tudinal bundle and the restiform body lies the substan- tia reticularis (Srt) of the tegmentum. Dorsally to it the ninth and tenth sensory nuclei. Laterally from it the dorsal nucleus of the eighth. In front of the resti- form body the descending root of the ninth, the tenth, and the solitary bundle (s) pass downward; beneath these the descending root of the fifth (Vc), laterally from the substantia gelatinosa (Sg). The fibres of the ninth and tenth nerves pass near by the solitary bundle out of the medulla. Medially from these in the tegmen- tum lies a nucleus (nucleus ambiguus), a cell group which is represented as a part of the motor nucleus of the vagus (?w) iind which can be seen better in the following sections. Median olive (olm), posterior olive (olp). 46 Tafel 38. Fig. 1. Fig. 2 Tafel 39. 2$m Fig. 2. Explanation of Plate 39. Fig. 1. — Section through the Medulla at the Level of the Tenth and Twelfth Nuclei. Close to the nucleus of the tenth and medially to it passes the hypoglossal (XII ) on the floor of the fourth ventricle, the fibres of which are penetrated externally by the posterior longitudinal bundle (/) and the fillet (L). Laterally to the olives pass the external arcuate fibres (far) from the restiform body to the fillet of the same side, and through the substantia reticularis the internal arcuate fibres (fed) from the fillet to the most mesial portion of the restiform body of the opposite side (cross- ing therefore in the raphe). Above the inferior olive (ol) and mesially to it lies the inner accessory olive (olm). From the restiform bodies the lateral cerebellar tracts (Cb) pass off more deeply toward the pyramids. Everything else as in the previous section. Fig. 2. — Section through the Calamus Script or ius of the M:dulla. The restiform bodies (cr) approach one another, the fourth ventricle (vIV) becomes closed. The nuclei of the posterior columns pass into the restiform bodies, medial the nucleus of Goll, lateral the nucleus of Bur- dach (>{fj>). From these nuclei pass the massive in- ternal arcuate fibres (fai) downward to the fillet (L) of the opposite side. The nucleus of the hypoglossus is more deeply situated (nXII). The nucleus of the tenth ends. Pyramids, fillet (L), substantia reticularis (Srt), substantia gelatinosa (Sy), descending root of the fifth (Vc), lateral cerebellar tract (Cb), solitary bun- dle (s), olives (ol), posterior longitudinal fasciculus (/), etc., unchanged. Kaphe of the tegmentum (A'). 47 Explanation of Plate 40. Fig. 1. — Section through the Nuclei of the Posterior Columns. Above the nuclei of Goll (nG) and Burdach (nB) the respective columns of these nuclei are to be seen dis- tinctly (fG and //>'). The central canal with the nucleus of the twelfth (NXII) has sunken more deeply into the medulla. The internal arcuate fibres (fai) and the external (fae) are plainly represented. All the other constitu- ents as in the previous section, except that the olives (ol) have become considerably smaller. Fig. 2. — Section through the Medulla beneath the Olives. After the disappearance of the olives the medulla be- comes considerably smaller. The nuclei of the posterior columns are smaller (NG, NB), the bundles which arise from them (funiculus Goll and Burdach) larger. Near and lateral to the nu- cleus of the twelfth the nucleus of the ninth has ap- peared, the fibres of which pass out transversely through the medulla. The lateral cerebellar tracts (Cb) are represented by a clearly differentiated area, dorsally from which is the substantia gelatinosa (Sy) and laterally the descending root of the trigeminus (Vc). Internal and external arcuate fibres, substantia reticularis (Sti), fillet (L) (which has become considerably smaller), fillet decussa- tion (A'), pyramids, inner olives. Between Goll's columns the posterior longitudinal sul- cus (Sjj), between the pyramids the anterior longitu- dinal sulcus (Sa). In the pyramids the nucleus arci- forinis (?ia). 48 Tafel 40. Tafel 41. ~- Fig. 1. S\ ■ranrafz X '.cert 1 Explanation of Plate 41. Fig. 1. — Section of the Medulla Immediately Above the Pyramidal Decussation. The pyramids (Py) are more deeply situated in the medulla and displace one another and thus push asunder the small tillet layer (fa). At their apices the posterior longitudinal fasciculus (/) is still to be seen. The in- ternal arcuate fibres (fai) pass distinctly out of the nu- cleus of Goll's column (nG) to the crossed fillet layer. The nuclei of the posterior columns (nG, nB) are smaller, the substantia gelatinosa (Sg) gets continually larger (beginning of the posterior horns). In the sub- stantia reticularis tegmenti (Srt) the area alongside of the remains of the fillet and the posterior longitudinal fasciculus is later to be the position of the anterior horns (corn. a). Laterally from this the substantia reticu- laris is displaced by the appearance of the antero-lateral ground bundle (fl) and the column of Gowers (G) and posteriorly the lateral cerebellar tract (CI). In the middle the nucleus cf the twelfth which has nearly dis- appeared and the nucleus of the eleventh which is still distinct. The accessory olives have disappeared. The spinal portion of the eleventh nerve arises from a group of ganglionic cells lying in the lateral segment of the anterior horn. Fig. 2. — Section through the Pyramidal Crossing. The nuclei of the posterior columns have disappeared, the territory is entirely taken up with the fibres of the posterior columns, Goll's and Burdach's columns CfG, fB). The pyramids pass decussating, severing the anterior horns (Z> Py), deeply into the lateral columns of the op- posite side. The posterior horn (Sg) is distinctly recognizable. All the other parts as m the cut above. Anterior horn (Ca), central canal (cc), sulcus anterior (Sa), sulcus posterior (Sj)). 49 Explanation of Plate 42. The sections from here on, in conformity with the usual cus- tom, are represented reversed. The dorsal portion (Sp) down- ward and the ventral (Sa) upward. Fig. 1. — Section through the Cervical Cord Immediate- ly Beneath the Pyramidal Decussation. The pyramids (Py) have in large part disappeared from the anterior columns and are found in the crossed pyramidal tracts. In the anterior columns remain the small uncrossed pyramidal tract {Pya) and the anterior ground bundle (fa) (from the posterior longitudinal fas- ciculus). In the lateral columns are found the crossed pyramidal tracts (Py); the antero-lateral ground bun- dle (fal), the lateral limiting layer (fi), and Gowers' bundle as a continuation of fibres from the substantia reticularis tegmenti; the lateral cerebellar tracts (Cb) from the restiform bodies (ventral segment). In the posterior columns lie the columns of Goll (fG) and Burdach (fB). At the bottom of the anterior longitudinal fissure lies the anterior commissure (d), the spinal prolongation of the pyramidal decussation, behind it the central canal (c.c.) and the posterior commissure. The anterior (Ca) and posterior (cp) horns are com- pletely developed and in the posterior horns the sub- stantia gelatinosa (Sg), which was remarked above, has become prominent. The roots of the uppermost cervical nerve pass here out of the anterior horn (anterior root), and in the lateral segment of Burdach' s column is seen the entering posterior root (in the posterior root zone). Fig. 2. — Section through the Upper Cervical Cord, Level of the Fourth Cervical Nerve. Lettering as in Fig. 1. The substantia gelatinosa (cp) of the posterior horn is much smaller, as it is in all the following sections. Origin of the phrenic in the anterior horn cells (Ca). 50 Tafel 42. -__^_ ----- ScL Tafel 43. ) Fig-i- V Fig. 2. Sp Explanation of Plate 43. Fig. 1. — Section through the Cervical Enlargement, Level of the Seventh Cervical Nerve. The gray substance on account of the enormous devel- opment of the anterior horns (Ca) is considerably in- creased. The composition is the same as given for Plate 42, 1. In the anterior horns are the cells for the periph- eral motor neurons of the arm muscles (at this level es- pecially for the forearm musculature). There are dif- ferentiated a mesal (small) (m) and a lateral (I) gan- glion-cell groups The lateral (and the mesal) divide further into an anterior and a posterior division (la and Ip). Further concerning localization is not known posi- tively. The lateral group may contain the proper moto- rial cells. Behind the motorial cell groups lie the so-called "middle cells" (c), around which ramify innu- merable collaterals from the posterior roots and also from the lateral columns. The posterior roots (rp) and their course are seen better in Plate 47, 1. Fig. 2. — Section through the Upper Dorsal Cord, Level of Third Dorsal Nerve. Fig. 3. — Section through Middle of Dorsal Cord, Level of Sixth Dorsal Nerve. The anterior horns have again become small and from them arise the peripheral neurons for the intercostal muscles. At the base of the posterior horns one can make out the rudiments of Clarke's columns (CI). Central canal (cr). Goll's columns get smaller the further down we go. The remaining relationships are unaltered. Anterior roots (ra), posterior roots (rp). 51 Explanation of Plate 44. Fig. 1. — Section through the Lower Dorsal Cord, Level of the Eleventh Dorsal Nerve. The anterior horns (Co) increase in size and their configuration becomes changed; Clarke's columns with their cells are large and sharply defined. From them fibres pass to the lateral cerebellar tract of the same side {CI) and pass with this tract to the crossed nu- cleus of the tegmentum in the restiform body. The lateral pyramidal tracts {Py) pass, below the starting- point of the lateral cerebellar tract, quite out to the periphery. The anterior pyramidal tract becomes smaller and is lost in the upper portion of the lumbar cord. All the other columns become smaller because they have given off the greater portion of their fibres in segments higher up. Fig. 2. — Section through the Upper Lumbar Cord, Level of Second Lumbar Nerve. Fig. 3. — Section through the Lower Lumbar Cord, Level of Fourth Lumbar Nerve. The anterior and posterior horns become very much extended. This is due principally to the increase of the gray substance. The cell groups in the anterior horns are similar to those in the cervical region. From them arise the peripheral neurons for the leg muscles. The posterior roots (rp) enter in thick bundles the posterior root zones, and their collaterals and short branches radi- ate bow form into the posterior horns. For further details see Plate 47, 2. 52 **&** Sa Tafel 44. FYa. 1. Ffjr. 2. F/gr. 3. Tafel 45. Fig. 2. w » ' » ■ 25%. 3. Explanation of Plate 45. Fig. 1. — Section through the Sacral Cord, Level of Third Sacral Nerve. The pyramidal columns terminate in the small white substance of the lateral columns. The gray substance is relatively greater than the white. In the broad an- terior horns are situated the motor ganglion cells that give origin to the peripheral neurons for the small mus- cles of the feet, somewhat lower are those for the anal and vesical muscles and their reflex automatic activity. Fig. 2. — Section through the Cauda Equina and the Conus Medullaris. In a sac of the dura lie the more deeply passing motor and sensory roots, given orf from the spinal cord in the lumbar region, for the lower extremities. Later- ally the roots which later form the crural (Pll), me- dially, the sciatic continuation (Pis). The first, after their exit, form the lumbar plexus, the other the sacral plexus. In the centre lies the inferior termination of the spinal cord, the conus medullaris (C m). Fig. 3. — Section through a Posterior Root and Spinal Ganglion from the Lumbar Cord. The mixed nerve (Np) coming from the periphery goes as far as the spinal ganglion, its sensory portion (rs) passes into the ganglion and ends in the cells of the latter (one can see despite the weak magnification the strongly pigmented cells of the ganglion). From it passes collectively the posterior root (rp) out of the ganglion and into the spinal cord (especially into the pos- terior root zone of the posterior column). Explanation of Plate 46. Fig. 1. — Section through the Sciatic Nerve at its Upper Point of Emergence. (Great sciatic foramen.) Enveloped by the epineurium (P), with, weak magnifi- cation one recognizes the numerous collected individual bundles (/) of varying thicknesses. Between them the blood-vessels course in the perineural connective tissue. Fig. 2. — Longitudinal Section oj a Nerve Bundle taken from the Sciatic Nerve. For explanation see Fig. 3. Fig. 3. — Transverse Section of a Nerve Bundle from the Sciatic Nerve. One recognizes with strong magnification the segrega- tion of medullated fibres (stained black) of different thick- ness. In all the nerve bundles there course without order, close to the thick fibres, numerous very small nerve fibres surrounded by a scarcely recognizable me- dullary sheath. In the nerve bundles individual com- partments are formed by the endoneural connective tis- sue. Fig. 4. — Cross Section through a Normal Optic Nerve (weak magnification), in its nerve sheath formed from the dura (>•). It consists also of numerous individual bundles in which the nerve fibres of very fine calibre course. 54 • # # l Tafel 4(3. Fig. 1. Fig. 4. Fig. 3. Explanation of Plate 47. The Gray Substance op the Spinal Cord. The two photographs represent with strong magnifica- tion the right half of a cervical section and the left half of a lumbar section (comp. Plate 43, 1 and Plate 44, 3). One observes particularly the enormous number of fibres going in and coming from the horns. In the an- terior horn there pass in : 1. Fibres from the anterior commissure (decussating anterior pyramidal columns and decussating central sen- sory fibres). 2. Fibres from the antero-lateral tract (motorial end fibres and collaterals from the lateral pyramidal tract and central sensory collaterals from the anterior lateral columns). 3. Fibres from the posterior horn (reflex collaterals and other posterior root fibres). From the anterior horn pass out the anterior (motor) roots arising from the motor ganglion-cell groups; they pass out in bundles through the antero-lateral tracts. (They arise especially from the lateral cell groups.) Into the posterior horn there passes the thick bow- formed radiations of the collaterals and the collected short tracts of the posterior roots from the posterior column. At the posterior end of the posterior horn formed by the substantia gelatinosa (Sg) lie the fields of Lissauer (medullary bridge), consisting of thin posterior root fibres (L), and immediately in front of them the zona spongiosa of the posterior horns. 55 Explanation of Plate 48. Medullation of the Foetal Brain (photographs). This plate follows immediately after Plate 11 and is used for the first time now on account of being more readily comprehended. Figs. 1 to 5 represent the unstained sections from the brain stem of a foetus eight months old. By far the greater number of fibres which in the fully developed brain are medullated are here unmedullated (therefore unstained). Nevertheless there are individual phylo- genetically manifest old and important tracts which are on account of their medullation easily recognized macro- scopically. They appear brilliantly white in contrast with the remaining gray matter of the brain stem. The most important of these tracts are : the medullary radiation to the red (nr) nucleus (Fig. 1, L), the ansa lenticularis and the fillet ( Ls, Li) . In addition to this there are also medullated the posterior longitudinal bundle, the nasal (descending) root of the trigeminus, the peripheral cranial nerves, the optic tract, the poste- rior commissure, and others. Figs. 1 and 2. — Section through the Middle and Pos- terior Segment of the Optic Thalamus. One observes that the crusta (motor pyramidal tract, etc.) is not yet medullated. Fig. 3. Section through the Anterior Corpora Quadri- gemina. Fig. 4. — Section through the Middle of the Pons. Fig. 5. — Section through the Medulla Oblongata. The fillet passes in the first section at the height men- tioned above almost entirely as a portion of the ansa lenticularis and further through the globus pallidus and (probably not interrupted) in the so-called tegmental radiation (the first medullated pathway of the cerebral hemispheres, sensory tract! See text, Section IV., p. 65) to the cortex of the posterior central convolutions and the parietal lobes. Figs. 6 and 7 are sections through the cervical cord and dorsal cord of a new-born. One recognizes the not yet medullated pyramidal tract (Py) sharply differen- tiated from the fully developed lateral cerebellar tract (Ob). For description of the dorsal cord see Plate 10, Fig. 2 (medullary sheath staining). 56 Tafel 48. Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. Tab. 49. Explanation of Plate 49. Scheme ok the Course of the more Important Cerebral Tracts. In the scheme, which is comprehensible without fur- ther description, there, are represented (1) transverse sections of the hemispheres, (2) the cerebral peduncles, (3) the pons, (4) the upper, (o) the lower medulla, and (6) the spinal cord. Their respective positions are clearly discernible in the plate. 1. Blue stippling, the frontal pons-cerebellar tract, from the pons ganglia to the opposite cerebellar hemi- sphere (1-3). 2. Yellow, the temporo-occipital pons-cerebellar tract, from the pons ganglia to the opposite cerebellar hemi- sphere (1-3). 3. Red, the motorial pyramidal tract (central neuron) decussates almost completely between 5 and 6 and passes in the cord, partly in the lateral column, partly in the anterior column to the motor nuclei of the medulla in the brain and to the motor nuclei of the anterior horns in the cord. 4. Green, the sensory fillet tract (central neuron), the important portion of the central tegmental tract (ansa len- ticularis). It breaks through the internal capsule, passes farther in the tegmentum as superior fillet, and in 5 (inter- nal arcuate fibres) decussates to the nuclei of the posterior columns. The greater portion is certainly interrupted somehow in the thalamus or in the subthalamic region. 5. From the thalamus passes a tract (brown) to the red nucleus, from there (2) the brachium conjunctivum decussates to the cerebellar hemisphere. 6. The lateral cerebellar tract (brown 4-6) passes from the spinal cord (Clarke's column) to the restiform bodies and so to the vermis of the cerebellum (crossed tegmental nucleus). 7. From the nuclei of the posterior columns on both sides fibres pass (green) to the cerebellum as external arcuate fibres to the restiform body (4-5). 8. From the olive (4) fibres (stippled yellow) of the opposite side pass to the cerebellum, olivary fibres of the restiform body. 9. In cross section of the cerebrum (1) the commissural tracts (brown) pass in the corpus callosum and the ante- rior commissure from the cortex of one side to the other. 57 Explanation of Plate 50. Figs. 1 and 2 show the relationship of the tegmentum and the foot of the cerebral peduncle to the cerebral hemisphere tracts. Fig. 1 shows the hemisphere on frontal section, Fig. 2 on horizontal section. In Fig. 1 are seen on the left the connections of the crusta, on the right the connections of the tegment. Crusta : frontal pons tract (blue), pyramidal tract (red), temporo- (parieto-) occipital pons tract (blue stippling). Tegment: fillet tract (green), thalamus — red nucleus (brown). In the section of the hemispheres there are represented schematically the long and short association tracts (brown), and the corona radiata to the thalamus (su- perior and inferior stalks) (brown). In Fig. 2 in addition, the optic radiations (occipital cortex — optic centres — optic tract) (yellow). Fig. 3. — Scheme of the Optic and Motor Oculi Tracts and their Connections. (The fibres of the left optic tract are colored.) Optic: peripheral neuron (brown) in the retina (b=bulb); central neuron (green), in the optic nerve to the chiasm (decussation of the nasal bundle) ; from there in the optic tract to the lateral geniculate body, pulvi- nar, anterior quadrigeminate body. Here the fibre arbo- rization occurs. From there the fibres pass in the optic radiations to the cortex of the cuneus of the occipital lobes (it is doubtful if there exist direct fibres from the tract to the cortex collaterals?). Motor oculi : central neuron (red) from the cortical centre (angular gyrus?) crossed to the motor oculi nu- cleus on the floor of the aqueduct. Peripheral neuron (blue), from there as peripheral nerve (of crossed origin also, for the rectus interims) to the musculature of the bulb. Pupillary reflex tract: optic fibres — corpora quadri- gemina — reflex collaterals (stippled yellow, where?) — motor oculi nucleus — peripheral nerve (blue) — sphincter papilla: (intercalated in ciliary ganglion). 58 Tab. 50. %./ Fig 3 Tab. 51. mg.3 if ilippoc Cortex cerebri q.cenl.p.eL pariet. Explanation of Plate 51. In Figs. 1 and 2 there are represented in transverse section of the hemispheres (1), the brain stern (2-4), and the spinal cord (cervical [5], lumbar cord [0]), the posi- tion of the (motor) pyramidal tract and the (sensory) fillet tract and their prolongations in the spinal cord. Fig. 1. — Bed, the Pyramidal Tract and its Position in the Different Levels. In 4 partial decussation: anterior pyramidal and lateral pyramidal tracts. Fig. 2. — Green, the Sensory Tract. In 6 entrance through the posterior roots. Further conduction : a. Uncrossed in Burdach's-Goll's columns as far as their nuclei in 3 ; b. Crossed (anterior commissure) and uncrossed (short tracts) after interruption in the gray substance of the antero-lateral ground bundle. Further course : in 3, decussation of those mentioned under a reach the fillet after interruption in the nuclei of the posterior columns (internal arcuate fibres). After the incorporation of the tracts mentioned under b (interrupted in the substantia reticularis?) the fillet passes (after receiving the central sensory tract for the cranial nerves) (for details see Fig. 3) through 2, 1 farther toward the cortex. Brown, the (sensory) lateral cerebellar tract (see Plate 49) and fibres from the nuclei of the posterior columns in 3 to the cerebellum. Fig. 3. — Scheme of the Sensory Nerve Tracts. The peripheral sensory neuron brown. The central sensory neuron green. Cells, course of fibres, terminations are evident in the scheme without further explanation. I., Olfactory tract; II., visual tract; VIII., auditory tract (cochlear nerve); V., IX., taste tract; see scheme of the cutaneous sensory tract and the related reflex tracts (shorter, longer reflex arcs). Explanation of Plate 52. Schematic Representation op the Course op the Fibres in the Spinal Cord. I. The Motor Trad. a. Central neuron (red) : Lateral pyramidal tract (Py I) and anterior pyramidal tract (Pya) ; terminal arborization in the an- terior born. b. Peripheral neuron (blue) : anterior horn cells — anterior root (r.a) — motor nerve muscle. II. The Sensory Tract. a. Peripheral neuron (brown) : sensory nerve (n.p), spinal ganglion (Sp) — posterior root (r.p) of the spinal cord. In the posterior root zone of the posterior columns each fibre divides into an ascending and a descending branch (short and long fibres) . The short tracts curve into the posterior horn as : 1. Reflex collaterals to the anterior horn, shorter reflex arc, longer reflex tracts (intercalation of another [green] neuron). 2. Fibres to the cells of the middle zone of the gray substance. 3. Fibres to the cells of Clarke's columns (c) . 4. Fibres to the central and especially the medial anterior horn cells (commissural cells) . 5. Fibres to the posterior horn cells. The long tracts (6) pass first into Burdach's column, higher also into Goll's column, and thus to the nuclei of the posterior columns in the medulla. (Here they join the fillet.) b. Central neuron (green). It begins with the cells of the terminal places of the peripheral, enumerated under 2 to 6. 1. From those which have been enumerated under 2 as "col- umn cells" arise the fibres of the anterior ground bundle of the same side (fat) (fl) and the columns of Gowers (O) . 2. From those mentioned under 3 : the lateral cerebellar tract of the same side (Cb). 3. From those under 4 : fibres which cross in the anterior com- missure to the anterior lateral column (fal) (fl) to ascend in the other side. 4. From those under 5 : fibres to the lateral limiting layer (fl) and to the ventral field of the posterior columns. In addition to this is represented the manner in which the col- laterals are given off and the termination of the central short tracts (which quickly bend again into the gray substance) of the anterior lateral columns, the "inland cells" (green, Golgi) in the posterior horn ; the decussation in the posterior commissure is not clear. There are contained in the posterior roots apparently Other individual fibres which have their neuron cells in the an- terior horn, but in man this is not yet satisfactorily established. 60 Tab. 52. IV. GENERAL PATHOLOGICAL ANATOMY OF THE NERVOUS SYSTEM. Demonstrated by Special Examples. TO ACCOMPANY SECTION IV. OF THE TEXT. SPECIAL PATHOLOGY OF THE BRAIN. TO WHICH BELONGS SECTION V. , PAGES 150 AND THE FOLLOWING OF THE TEXT. SI Tab, 53. Ftgl Fig '2 SECONDARY DISEASES OF THE NER- VOUS SYSTEM. Explanation of Plate 53. Fig. 1. — Section through the Cortex and Meninges of the Brain in a Case of Epidemic Cerebro- Spinal Menin- gitis. The preparation is from a soldier, 23 years old, who was taken suddenly ill with general febrile manifesta- tions, vomiting, and headache. Stiffness of the neck, as- sociated with pain, continuous high temperature (40° C.) ; herpes labialis, and leucocytosis of 36,000 established the diagnosis. Following this there was increasing dis- turbance of consciousness, motorial irritation symptoms such as twitchings of the face muscles and the arms, espe- cially the right, and delirium. Death in deep coma six days later, the stiffness of the neck and trunk muscles still continuing. Autopsy : On and in the meninges of the brain and spinal cord were found purulent, thick, white masses which covered the convexities especially. The process was most severe in the middle of the left central convo- lutions. In the pus the diplococcus of Fraenkel. The purulent infiltration (colored red) sunk into the fissures following the pia into the cortex. The cortical cells were very much damaged by the inflammatory products, and thus their function was inhibited. Fig. 2. — Cerebral Cortex from a Case of Tubercular Meningitis. A 30-year-old woman, who had suffered previously from tuberculosis of the lungs, was admitted twenty days before her death. Symptoms : high fever, head- ache, delirium, gradually developing coma. Ptosis of the eyelids, dilatation of the pupils, convulsions. Diag- nosis : miliary tuberculosis. Autopsy: the meninges studded with small whitish- gray particles. On the base of the brain an exudation in the sulci which completely embedded the motor oculi. The preparation shows one of these tubercles in the depths of a sulcus. It has caused by its increase in size displacement of the cell layer of the cortex. A collec- tion of such solitary tubercles may form a large tumor (especially in children). Here we have the opposite to the disseminated variety of tuberculosis. as Explanation of Plate 54. Fig. 1. — An aneurism (An), lying closely over the corpora quadrigernina which has produced softening, es- pecially in the region of the tegmentum of the cerebral peduncle (T) and the corpora quadrigernina. The pa- tient, a man 53 years old, had the following symptoms : headache, vertigo, paresis of the left arm and leg, com- plete hemianaesthesia of the same side, ocular paraly- sis in the right eye, such as ptosis, paralysis of the sphincter pupillse of the superior rectus, etc. Fig. 2. — Caries of the Spinal Column. The preparation from a woman, 45 years old, who be- came sick with pain in the back and sides, associated with increasing weakness of the legs. After three months inability to stand and the presence of mild sen- sory and bladder disturbances. Tendon reflexes exag- gerated. Irregular fever ; nothing abnormal in the spinal column. Eventually complete paralysis of the legs, con- tracture formations. An intercurrent cold abscess in the thorax corroborated the diagnosis of compression of the spinal cord secondary to caries of the vertebral column. Autopsy : Carious focus in the eighth dorsal vertebra (C); numerous granulations and caseous masses filled the spinal canal and caused compression of the cord and the outgoing roots (f). v, body of vertebra; pr. sj), spinous process. Fk;. 3. — A tumor (T), arising from the inner surface of the dura (d), extending into the central canal, devel- oped in a woman, 38 years old, with symptoms of se- vere pain in both legs, and in the course of three months complete spastic paralysis of both legs, as well as com- plete anaesthesia of the same (except cold was taken for hot) and incontinence of urine. Death resulted from cystitis and pyelitis. Diagnosis: Compression of the spinal cord (carci- noma'.''). The tumor proved to be a sarcoma which com- pletely filled the vertebral canal from the second to the sixth dorsal segments. 64 Tab. 54. Tab. 55. #3& Fig.1 ret Fig. 2 Cerv. Dcgenasc focus. Defltner. desc. Fig 3 Lumb Explanation of Plate 55. Fig. 1. — Gumma of the Base of the /train. The syphiloma (y) lias its origin from the meninges, lies in the vicinity of the adventitia of a blood-vessel (a), and is in part proliferated from the latter which shows the characteristic luetic endarteritis. Proliferation of the tunica intima has gone on to such an extent that the lumen of the vessels has become narrowed and nearly ob- literated. The process has extended so that the neigh- boring branch of the vagus is encroached upon. The preparation is from a patient, 20 years old, who had suffered repeated strokes and in whom paralysis of the left abducens and facial nerves persisted. The autopsy showed several small gumma formations iu the basal meninges, adhesive and cloudy condition of the latter, arteriosclerosis of the blood-vessels of the brain, and multiple foci of softening in the hemispheres. PRIMARY DISEASES OF THE NERVOUS SYSTEM. Fig. 2. — Section through the Anterior Horn of the Cer- cicul Cord in a Case of Spinal Muscular Atrophy. The cells of the anterior horn are primarily diseased, atrophied, their protoplasmic prolongations are very much less numerous than normal, and in part they have en- tirely disappeared (compare Plate 20, 2). The anterior roots are atrophic, secondary to the disappearance of the anterior horn cells. The degeneration extends seconda- rily throughout the entire extent of the neurons. There is degenerative atrophy of the motor nerves as well as of the muscles, due to the loss of the protoplasm. The nerve cells exercise a preservative influence on the fibre of the neuron and the muscles to which it is distributed. Pig. 3. — Scheme of Secondary Degeneration in the Spinal Cord (see Plates 65-68). If the continuity of a spinal-cord tract is interrupted by disease [or injury] there will result secondary column degeneration, because the neuron fibre is severed from its cell. The tracts that degenerate downward (" descend- ing") are especially the pyramidal tracts (neuron cells in the cortex), Goll's columns (spinal ganglion cells), the lateral cerebellar tracts (cells of Clarke's columns), and Gowers' column (cells in the middle zone of the gray substance). 65 DISEASES OF THE GANGLION CELLS. Explanation of Plate 56. Fig. 1. — Section through a Portion of the Hypoglossal Nucleus in Bulbar Paralysis. The nucleus is poor in fibres, its cells have become extremely small, shrunken, their protoplasmic prolonga- tions have disappeared (compare Plate 20, 1), and in consquence of this the clinical manifestations were par- alysis and atrophy of the musculature of the tongue and severe form of speech disturbance. Fig. 2. — Cortical cells from a necrotic area of soften- ing in the brain which was secondary to embolic occlu- sion of an artery ; the area is seen to contain innumerable small fat bodies, products of destruction which have been stained black with osmic acid. Fig. 3. — Nucleated cells unstained. The free fat corpuscles are carried into the protoplasm by leucocytes and in the same way transported further. Fig. 4. — In foci which are the result of hemorrhages, coloring matter of the blood remains in the form of clumps of pigment and partly in the form of crystals stored in cells where it may be recognized a long time afterward. Fig. 5. — Amyloid bodies are found among other places in parts of the spinal cord which are the seat of degen- eration, such as in tabes. Their significance is not en- tirely clear. Fig. 6. — Advanced degree of cell and fibre atrophy in the anterior horns of a spinal cord affected with amyo- trophic lateral sclerosis. Many of the cells are scarcely recognizable (compare Plate 20, 2). Fig. 7. — Acute inflammatory process in the anterior horn of the lumbar cord in a case of anterior poliomye- litis. Numerous dilated blood-vessels surround the af- fected ganglionic cells, which latter are undergoing par- tial dissolution (granular disintegration). The process terminates by the formation of scar tissue after the de- struction of the nerve elements. Fig. 8. — Scar in the anterior horn, the result of a former hemorrhage into the substance of the spinal cord (haematomyelia). The gray substance (cells and fibres, etc.) is destroyed and its place is occupied by cicatricial connective tissue with embedded clumps of pigment. 66 Tab 56. F ig 1 Fuj2 n g 3 i W 1 6-7 1% ^.5 Fig. 8 N§ « Tab. 57. % 3 Fig 5 Fig Explanation of Plate 57. Diseases of the Nerve Fibres. Fig. 1. — Nerve fibres whose medullary sheaths are in a degenerated condition; the fibres are swollen, the substance of the medullary sheath is disrupted, melted to drops, and in part resorbed. The axis cylinder almost always perishes first. Fig. 2. — Section through a degenerated column of the spinal cord. The fibres which normally are closely packed together (see Plate 21, 1) are in consequence of the destruction of fibres widely separated one from an- other, and in the places of the degenerated nerve fibres there is seen newly formed glia tissue, the entire process being called sclerotic formation. Fig. 3. — Myelitic scar. In a column of the spinal cord bundles of fibres have disappeared and in their place a network of glia tissue has formed which is filled with blood-vessels with thickened and infiltrated walls. This process is called total sclerosis. Fig. 4. — Section through a small sensory cutaneous nerve in tabes dorsalis in which a portion of the medul- lated fibres (stained black) have perished. Fig. 5. — In multiple sclerosis there develop foci within which the medullary sheaths of fibres are destroyed while the axis cylinder is in part preserved. Here also there occurs a formation of connective tissue in which the naked axis cylinders become embedded, a, medul- lated fibre; b, free axis cylinder. Fig. 6. — Horizontal section through the internal cap- sule. The cerebral motorial tracts (pyramidal tracts) have here suffered primary degeneration. Weak magnifica- tion of these preparations made with a medullary sheath stain shows the degeneration as light, clear areas in the middle of the surrounding normal black-stained fibres. These areas are also the places in which these tracts tra- verse the internal capsule and which are here clearly marked out. (Compare Plate 30, middle.) 67 Explanation of Plate 58. Diseases of the Muscle Fibres. Fig. 1. — Normal transverse section of muscle in com- bination with transverse section of polygonal muscular fibre of small size with few cells. Figs. 2 and 3. — Transverse and longitudinal section of muscles from a case of spinal muscular atrophy (bi- ceps muscle). There is great dissimilarity in the thick- ness of individual fibres. One part has entirely disap- peared, another is very much smaller (p). The muscle nuclei are very much increased and constitute rows of nuclei. The transverse striation of the protoplasm has disappeared in the degenerated fibrillae and the proto- plasm has become granular. Fig. 4. — Juvenile muscular atrophy (progressive mus- cular dystrophy. Quadriceps muscle). Here whole bundles of muscle fibre have disappeared, the nuclear proliferation is striking, and many fibres are hypertro- phic. Transverse striation remains for a long time in spite of the extensive atrophy of the fibres. Frequently there is a deposition of fat between the muscle fibrillae that are preserved (pseudo-hypertrophy). At h a so- called hypertrophic muscle fibre. Fig. 5. — Neurotic form of muscular atrophy (oppo- nens pollicis muscle). One recognizes the great lessen- ing in size of the fibrillae and the nuclear proliferation. The transverse striations remain clear for a long time. Fig. 6. — Unstained muscle fibre: a. Degenerative muscle atrophy from the quadriceps muscle in a case of lumbar myelitis. There is a gran- ular, cloudy condition of fibrillae, the transverse stria- tions have disappeared, the fibres have become irregular and small. Toward the end there is a resorption of the destroyed protoplasm, the empty sarcolemma sheath re- maining. r. Blight neural muscle atrophy, small fibres with nucleated cells and preserved transverse striation. 68 Tab. 58. * . F ig y Fig. 6 Figk Tafel 59. Fig. 1. Explanation of Plate 59. Fig 1.- — The left hemisphere of a man, 56 years old, who developed after repeated strokes a spastic paralysis of the right facial and hypoglossal nerves, of the right arm, and a weakness of the right leg (right-sided hemi- plegia). In addition to this there was a loss of volun- tary speech (motor aphasia), defective understanding of words and of writing (word dumbness, loss of optic memory pictures). After three years, during which time dementia kicreased, he died. The photograph shows the outer surface of the left hemisphere, a great part of the cortical convolutions is destroyed (porencephaly). Entirely transformed into connective tissue are : the posterior portion of the mid- dle and the inferior frontal convolutions (g.fr.m and i), the upper and middle temporal convolutions (g.t.s and m), the inferior parietal lobe (l.p.i), and in great part the anterior and posterior central convolutions, especially in their inferior portions Q/.e.a and ])), and the middle of the occipital lobes (o). Under the cortex the island of Reil and the medullary substance are extensively de- stroyed. Fossa of Sylvius (fS), fissure of Rolando (SB). Fig. 2. — View of the third ventricle opened (the cor- pus callosum and fornix removed). Complete destruc- tion of the left thalamus and its environs (corpora quad- rigemina, internal capsule). A man, 50 years old, had a stroke ; three days later when he regained consciousness there was right-sided hemiplegia (face-arm-leg). Simultaneously there oc- curred a paralysis of the motor oculi of the left eye (hemiplegia alternans). Speech was not disturbed, but there was right-sided hemianesthesia. The extensive focus was the result of a hemorrhage. Beneath the thalamus opticus of the left side the sub- thalamic region and outside it the posterior limb of the internal capsule were destroyed. In addition there was destruction of the left corpora quadrigemina (cqa) and the region of the tegmentum with the left motor oculi nucleus. (Th, thalamus; Pulv, pulvinar; cm, median commissure in the middle; ca, anterior horn of lateral ventricle; Cst, corpus striatum; c.c, corpus callosum). 69 Explanation of Plate 60. Fig. 1. — Section through the anterior quadrigeminal bodies, in complete destruction of the left tegmental re- gion (t) ; the left quadrigeminal body is atrophic. The nuclear region of the left motor oculi beneath the aque- duct of Sylvius (AS) is destroyed. The tegmental re- gion, the red nucleus, superior and inferior fillet, sub- stantia reticularis, etc., are entirely absent and the left crusta is completely atrophic. Clinical condition as in case of Plate 59, Fig. 2 ; alternating hemiplegia. Fig. 2. — Section through the medulla of a young girl who had inherited a tuberculous tendency. She became sick rather suddenly with headache, vomiting, increas- ing weakness of the right leg and later of the right arm. Soon after there occurred paralysis of the facial and of the hypoglossal nerves on the left side (hemiplegia alter- nans), paralysis of swallowing, and sudden death. The autopsy showed a tumor of the pons, which had extended far into the medulla (tubercular) and had thus destroyed the pyramids and outgoing facial and hj-po- glossal nerves. The tumor was a solitary tubercle with an enormous number of giant cells. Fig. 3. — We have considered previously foealdiseases of the brain. The accompanying preparation shows a system disease of the same: chronic progressive ophthal- moplegia. The cells of the motor oculi nucleus (NI1I) are primarily degenerated and the normal number of fibres of the outgoing motor oculi nerve is greatly dimin- ished (IIP) (compare normal section Plate 35, 2). The disease occurred in a woman sick with tabes. It caused a slowly developing paralysis of all the eye mus- cles. (c.pf posterior commissure; Sn, substantia nigra; nr, red nucleus.) 70 rafel GO. Wig. 1. Mg. 2, ig. :;. Taf.61. Fig. 1. Fig. 3. Explanation of Plate 6 1 . Secondary Degeneration in the Crusta. Figs. 1 and 2 are cross sections through and closely beneath the anterior corpora quadrigemina. There is a complete atrophy of the right pes pedunculus cerebri (x). The preparation is from a case of extensive primary de- struction of the cortex of the brain. As the fibres of the peduncle have their neuron cells in the cortex, it fol- lows that after the degeneration of the latter a second- ary descending degeneration must follow. The fillet tract is smaller on the right side than on the left, but it is not totally degenerated (simple, not degenerative atrophy). The fillet fibres have their neuron cells not in the cortex, but partly in the nuclei of the posterior columns and partly in the subthalamic region and in the thalamus. Clinically there had been total left-side hemiplegia). (tro, optic tract ; Sn, substantia nigra; L, lemnis- cus; eqa, anterior corpora quadrigemina.) Fig. 3. — Section through the anterior quadrigeminal bodies in total secondary atrophy of the most mesial pe- duncle bundles (frontal pontine tract) (x). This partial pes pedunculi degeneration resulted secondarily to an area of embolic softening which had destroyed the limb of the capsule and the lenticular nucleus. Clinically there had been no indicative symptoms. (cgm, medial geniculate body ; eg, lateral geniculate body; c, pineal gland, etc.) These and the following examples of secondary de- generation in the brain and spinal cord are for neurology especially of great significance^ because it is by the course of such degeneration that the different tracts have been made certain. We utilize the experiments made on animals inferentially in man. On such grounds have been developed the considerations here given. It forms a good repetition of what is given in Section III. 71 Explanation of Plate 62. Secondary Degeneration in the Cerebral Peduncles. Fig. 1. — Section through the Third Ventricle (middle commissure). Beneath the lower border of the thalamus which has been severed above (Th) is situated the re- maining portion of the subthalamic region (Luys' body) (cL), medullary substance of the red nucleus (L), be- neath it the internal capsule (posterior limb) before its exit as pes pedunculus cerebri. In the middle part of the latter (x) is an area of degeneration secondary to a destructive focus (hemorrhage) in the central convolu- tions. The degenerated area represents a part of the pyramidal tract. Fig. 2. — Section through the Anterior Corpora Quadri- gemina of the same Case. One recognizes here the posi- tion of the degenerated pyramidal tract (Py) in the middle of the pes pedunculus cerebri; it involves the en- tire pathway (not totally degenerated here) and in addi- tion a large area lateral to the degenerated portion. Clinically there had been left-sided hemiparesis of the face, arm, and leg. (tro, optic tract; /, the descending pillar of the fornix which passes backward to the mammillary body; AS, aqueduct; cL, subthalamic body, etc.) 72 Tafol 62. Fig. 1. Fig. 2. Tafel 63. Fig. 1. Fig. 2. Explanation of Plate 63. Secondary Degeneration in the Pons. Fig. 1. — Section through the Anterior Half of the Pons. The section belongs to the case Plate 61, 1 and 2. The fibres of the crusta on the left pass through in many bundles between the transverse fibres of the pons ; on the right these are absent, as are also the ganglia of the pons, and to this is due the enormous shrinkage of the right half of the pons. The tegmental region is normal. It is, however, to be seen that the secondary degeneration does not confine itself to the fibres that lie between two directly connected neuron ganglion sys- tems, but involves their cells as well. Fig. 2. — Section through the middle of the pons, with extensive secondary degeneration in the tegmental re- gion. The preparation is from the case Plate 59, 2 (left-right!). Both brachia conjunctiva (B) (in part, right at z) (neuron cells in the destroyed red nucleus), are degenerated ; then in the right tegmentum the central tegmental tract (ct), the entire upper fillet (y) (neuron cells in the destroyed subthalamic region and in the thalamus?), the nasal trigeminus root (Vn), the right pyramidal tract (x) in part, and other tracts are degen- erated. (Vm, motorial; Vs, sensory trigeminus nucleus and between the two the descending root ( Vc) ; /, posterior longitudinal fasciculus ; Ls, superior; Li, inferior fillet.) 73 Explanation of Plate 64. Secondary Degenerations in the Medulla. Fig. 1. — Section through the Medulla just behind the Pons. The left pyramidal tract (x) shows total secondary degenera- tion, the result of primary destruction of the posterior limb of the internal caspule by a hemorrhage (right-sided hemiplegia). One sees here the well-known course of the left stride acusticae passing from the ventral acoustic nucleus decussating over the floor of the fourth ventricle (to the fillet) . Fig. 2. — The Medulla from a Case of Infantile Cerebral Palsy. The preparation is from a man, 30 years old, who developed in his early youth (congenital? acquired?) a cessation of develop- ment of the entire right side of the body. There was flexion contracture, and paresis of the right arm and weakness of the right leg. Epileptiform attacks, athetosis. Upper arm. Forearm. Length of j Right, 29 cm. Circum- (Right, 21 cm. Right, 19cm. j Right, 29 cm. Circum- \ \ Left, 31 " ference, \ arms, \ Left, 31 " ference, \ Left, 24 " Left, 24 " ™ c .... , ( Right, 35 cm. _ ., ( Right, 29cm. Circumference of thigh, j ^ w .. Calf, j ^ ^ „ Autopsy: The left central convolutions are shrunken (agene- sis?), the left pyramid (x) entirely atrophied, likewise the left fillet without strict degenerative loss of fibres, due to the fact apparently that the disease confined itself to one side, as the medullary sheaths were also involved. The raphe was entirely displaced toward the left side and the right pyramid almost hypertrophied (compensation?). Fig. 3. — Medulla Oblongata, Case of Atrophy of the Fillet. The right fillet (Lx) is degenerated in a descending direction and with it the internal arcuate fibres (fai, y) of the substantia reticularis (Sr) of the left side ! These arciform fibres form the direct continuation of the crossed fillet and connect it with the nuclei of the posterior columns (?iO) which pass up in the resti- form bodies (Or). Pyramids (Pyx). The clinical condition was hemianesthesia of the left side of the body. 74 Fig. 2. Tafel 64. Fig. 1. Fin 3. ** s* Taf.65. /■'/i/. ■">. Fig. I. Explanation of Plate 65. Descending Degeneration of the Pyramidal Tract in the Cord from a Focus in the Brain. The preparations belong to the case Plate 64, Fig. 1. The left pyramid is totally degenerated (secondary), and this degeneration may be followed in this tract throughout its entire extent in the spinal cord, also through the pyramidal crossing of the lateral tract (crossed tract) and in the anterior tract of the same side (uncrossed tract). The lateral pyramidal tract {Py) is sharply defined from the normal lateral cerebellar tract in the cervical and dorsal region, but in the lumbar cord the pyramidal tract approaches the periphery, giving a wedge-shaped appearance. The anterior pyramidal column (x) is de- generated as far as the lower dorsal segments. In the anterior horn no change of any singificance is to be seen. The degeneration is confined to the central motor neuron, the pyramidal tract, in its entire course. Fig. 1. — Cervical cord (level sixth cervical nerve). Fig. 2. — Dorsal cord (level third dorsal nerve). Fig. 3. — Lumbar cord (level second lumbar nerve). Fig. 4. — Sacral cord. 75 Explanation of Plate 66. Descending Degeneration in the Spinal Cord in Spinal-Cord Diseases. Fig. 1. — Lower Cervical Cord. Fig. 2. — Lower Dorsal Cord. Fig. 3. — Upper Lumbar Cord. The preparations are from a man, 40 years old, who suffered a fracture of the cervical spinal column, the result of a fall, which caused crushing of the lower cer- vical cord. There resulted : complete spastic paraplegia of the legs, muscular atrophy and paralysis of the small muscles of the hands, anaesthesia, incontinence of urine, etc. Autopsy : The lower half of the area of compression involved the cervical cord: descending degeneration of both lateral pyramidal and anterior pyramidal tracts, as well as a comma-shaped area (Schultze's comma, ascend- ing fibres arising from the gray substance) in Burdach's columns, also a pale area in GolPs columns. It is to be observed that to the left lateral pyramidal column tract there belongs a small anterior column tract, to the right a not sharply defined anterior column tract (individual peculiarities). In the dorso-lumbar cord there is double- sided degeneration of the pyramidal tracts. The degen- eration of the posterior columns has disappeared (short tracts). Fig. 4. — Lumbar Cord in Compression of the Dorsal Cord. The preparation is taken from the same case as Plate 64, Fig. 3, a sarcoma of the dura. Below the point of compression there occurred a degeneration in the pyram- idal tracts of both sides and a slight degeneration in the border zone of the anterior lateral tracts (descending branches from the gray substance [middle zone] of the central sensory neurons). The large number of fibres radiating into the anterior horns from the posterior horns and anterior roots is clearly represented. 76 Taf. 66. Fig. Explanation of Plate 67. Ascending Degeneration in the Spinal Cord. A soldier, 22 years old, received a severe fall on the lower dorsal spinal column which resulted in fracture of the bone and transverse crushing of the lumbar cord. The consequences were a complete flaccid paralysis of the lower extremities, which was followed by rapidly de- veloping muscular atrophy of a degenerative type and dis- turbances of sensibility, paralysis of the sphincter of the bladder and rectum, and loss of patellar reflex. Death from cystitis two months later. Fig. 1. — The Crushed Upper Lumbar Cord. Fig. 2. — Middle Dorsal Cord. Here is to be seen a secondary ascending degeneration of the columns of Goll (neuron cells in the spinal ganglia). Fig. 3. — Lower Cervical Cord. Goll's columns (fG) show a wedge-shaped area of degeneration; their surface is very much smaller than in sections from a lower level. In addition there is to be seen here an ascending de- generation of the left lateral cerebellar tract (C6) and of the left column of Gowers (6r). (As can be perceived in Fig. 1, the gray substance and Clarke's columns are very much more extensively destroyed than the right; here lie the neuron cells for those columns.) Goll's columns conduct accordingly the long sensory tracts from the lower extremities upward; these fibres lie laterally to those that enter higher up, the long tracts from the trunk and upper extremities (Burdach's col- umns). 77 Explanation of Plate 68. Ascending Degeneration in the Cervical Cord and the Medulla. Fig. 1. — Ascending Secondary Degeneration in the Cer- vical Cord consequent to primary acute dorsal myelitis. As the result of the interruption of continuity of the fibres in the dorsal cord, the following columns degen- erate in an ascending direction on both sides : Goll's columns (fG), the lateral cerebellar columns (Cb), and Gowers' columns with their posterior gussets. Fig. 2. — Section through the Pyramidal Crossing. Ascending degeneration in chronic (syphilitic?) mye- litis of the dorsal cord. Goll's columns (fG), the lateral cerebellar columns (Cb), and Gowers' columns (G) are degenerated. Fig. 3. — Section through the Medulla at the level of the inferior olives. The preparation is from the same specimen as Plate 67 and follows immediately after the section of Fig. 3. One can recognize the ascending degeneration of Goll's columns (fG) which at this level have passed into the nuclei of Goll (nG). The degeneration has not affected the terminal fillet fibres (a new individual neuron!). The degeneration of the left lateral cerebellar tract is clearly apparent (Cb). In consequence of the somewhat oblique course of the section only the left olive is included. (L, fillet; fai, internal arcuate fibres; olm, median olive, etc.) 78 Tafel 68. \Fig. 1. ^3 Fig. 2 Fig. 3. V. SPECIAL PATHOLOGY OF THE SPINAL CORD AND OF THE PERIPHERAL NERVES. (To which Belongs Section V., Pages 188 et seq. of the Text.) 79 Tafel 69. Fig. 1. Fig. 2. Explanation of Plate 69. Forms of Myelitis. Fig. 1. — Acute Column- Form Myelitis (Toxic). Cervical Cord. A man, 42 years old, developed sequentially to a severe ery- sipelas, first painful sensitiveness of the arms and legs, which was quickly followed by paresis but not complete paralysis, slight disturbance of sensibility and of the function of the bladder (pain sensation normal) , terminal diaphragm paresis. Duration of dis- ease only four months. Diagnosis : Multiple neuritis. Autopsy : Extensive myelitic degeneration of the posterior columns (fG,/B), which reached from the cervical to the lumbar cord region ; myelitic foci in the lateral columns, espe- cially of the cervical cord ; slight changes in the nerves. The case would seem to indicate that conduction through the posterior columns for the sensibility of the skin is not necessary. Fig. 2. — Chronic Myelitis (Syphilitic?) of the Dorsal Cord. A 48-year-old man (probably syphilitic) sickened with slow, progressive weakness of the legs, no pain. After eighteen months complete paraplegia, sensibility in all qualities lost ; patellar reflexes lively ; incontinence. Autopsy showed a diffuse, widespread myelitis extending over the entire transverse section of the cord, its severest manifesta- tions being between the seventh and ninth dorsal segments. Be- neath this the pyramidal tracts were the seat of descending degen- eration. Above the sections appear as Plate 68; Fig. 2 of that plate being from this case. Fig. 3. — "Compression Myelitis.''' A carcinoma of the third dorsal vertebra which caused a compression of the dorsal cord and resulting severe degeneration of fibres in all parts of the section. The case was that of a woman, 42 years old, who began to be sick with severe neuralgic pains in the back, which was quickly followed by paresis of the lower extremities ; these increased until she was bed-ridden and were associated with some disturb- ances of the bladder and of sensibility. After three months complete paraplegia, formation of contractures, and such severe pain that it could scarcely he controlled by morphine. Duration of disease six months. 81 Explanation of Plate 70. Syringomyelia. Fig. 1. — Hydromyelia of the Upper Dorsal Cord. (Professor von Strumpell's Preparations.) A man, 35 years old, hereditary tendencies, sickened with slow, increasing weakness and stiffness of the legs; soon after of the arms, with increase of the tendon re- flexes; spasm of the muscles became aggravated; no muscular atrophy, sensibility normal. Diagnosis: Spastic spinal paralysis. Autopsy : Hydromyelia with degeneration of the py- ramidal tracts. The central canal in its entire extent was distended into a wide, irregular cavity filled with fluid (hydro- myelus). Congenital? Figs. 2 and 3. — Sections through the Upper and Mid- dle Cervical Portions of Another Case of Syringomyelia. The cavity formation extends partly in the anterior, partly in the posterior horns, entirely penetrating the latter. The clinical course was as follows : A man, about 40 years old, developed emaciation of the right hand, the right arm, and later of the left arm and hand ; the muscles of the ball of the thumb, hypothenar emi- nence, and interossei showed the degenerative atrophy first. On the arm the pain and temperature sensibility were entirely lost, the touch sense normal. Later there occurred trophic disturbance in the hands, inflammatory necrotic process in the phalanges, finger nails, and in the joints. In Fig. 2 a partial ascending degeneration of Goll's columns (x) is recognizable consequent to the involvement of the posterior columns by the cavity formation of Fig. :;. Tafel 70. Fig. 1. Fig. 2. Fig. 3. Tafel 71. Fig. 1. Fig. I. Explanation of Plate 71. Multiple Cerebro-Spinal Sclerosis. A woman, 25 years old, remarked for several months that there was an increasing weakness of the hands; tremor and uncertainty on grasping anything (inten- tional tremor) ; to which later were added a stiffness and uncertainty of gait, nystagmus, scanning speech, optic atrophy (white, pale papillae), increased tendon reflexes, sensibility normal, slight vesical disturbance. In three years the woman was completely bedridden and death followed a pneumonia. Autopsy: In the brain and spinal cord were found regularly diffused sclerotic foci, within which the me- dullary sheath of the nerve fibres had become striated and disappeared, the axis cylinders remaining in part intact. Fig. 1. — Longitudinal Section through the Dorsal Cord shows a sclerotic focus (/) in the posterior columns which have been cut through by the section. Figs. 2 and 4. — Transverse Sections of the Dorsal Cord. In 2 the entire transverse section is affected; only a part of the antero-lateral tracts is preserved. The gray substance of the anterior and posterior horns is diseased. In 3 there is a small area to be seen in the posterior columns and in the anterior-posterior horns, especially on the left side. Fig. 3. — Section through the Cerebral Cortex of the hemispheres. In the radiating medullary substance are two small sclerotic foci (x). Similar foci were found in the brain stem, pons, me- dulla, and in the cerebellum. 83 Explanation of Plate 72. Fig. 1. —Section through the Medulla of ar Case of Chronic Bulbar Paralysis with Amyotrophic Lateral Sclerosis. A man, 30 years old, was taken sick with a slow, progressive atrophy and paralysis of the small muscles of both hands. Soon following there was distinct hindrance of speech (bulbar speech), the movements of the lips and tongue became slow, and the in- volved muscles continued to atrophy and there were lively fibril- lary muscular contractions of the tongue. The gait was very slow and stiff. After two years there was complete atrophy and paralysis of the tongue and lips, paralysis of swallowing, speech impossible, arms entirely atrophic, and spastic paresis of the legs. Death from pneumonia of swallowing. Preparations show : severe loss of cells and fibres in the hypo- glossal nucleus (see Plate 56, 1), lightening in the pyramids. In the facial nucleus also a loss of cells. Fig. 2. —Section through the Lower Cervical Cord of a Case of Amyotrophic Lateral Sclerosis. The clinical course of the disease was very similar to the above-described case, except that in uncomplicated cases bulbar symptoms do not show themselves. Degenerative, slowly in creasing atrophy of the muscles of the upper extremities begin- ning in the thenar and interossei groups ; spastic paresis of the legs ; sensibility and bladder intact. Increased, lively reflexes. Preparations show : severe loss of cells and fibres in the anterior horns (diminution in size of the same) and degeneration of the pyramids on both sides. Fig. 3. — Section through the Anterior LLorns of the Cervical Cord in a Case of Spinal Muscular Atrophy (Striimpell). A man, 35 years old (bad heredity), became sick with atrophy and paralysis of the thenar muscles and of the interossei. In the course of years the atrophy involved all the muscles of the arms, the shoulder girdle, the rib and neck muscles. Reaction of de- generation in the muscles, fibrillary twitchings, sensibility nor- mal. No bulbar manifestations, no disturbance of gait. Preparations : Striking lessening in size of the anterior horns. Marked cell disappearance in the anterior horns (see Plates 56, 6 and 56, 2) . The anterior roots are also atrophic (compare their radiations in Plate 47, 1). In the anterior horns a close network of cicatricial glia tissue. Lateral columns normal. 84 Tafel 72. Fig. 2. Fig. 3. Fig. 1. Tafel 73. Fig. 8. Explanation of Plate 73. Tabes Dorsalis. In tabes there is degeneration in part of the fibres of the peripheral sensory neurons, most frequently of the lower ex- tremities, more seldom of the arms and face (trigeminus). Where the primary seat of the lesion is, it is not possible to say (neuron cells of the spinal ganglia?) . The first to be diseased in all probability are certain reflex tracts (collaterals from the pos- terior roots), then the posterior roots (see Plate 77, 5) in their entire course, and the short fibres that pass into the posterior horns, Clarke's columns as well as the fibres of the long tracts (those that pass from the roots of the lumbar cord to the columns of Goll). The peripheral portion of the neurons is always de- generated (sensory cutaneous nerves). (See Plate 57, 4.) Fig. 1. — Section through the Lower Dorsal Cord. The posterior columns are enormously degenerated ; the greater part of the ascending and descending fibres from the posterior roots are degenerated. The ventral field (v) of the posterior columns does not come from the posterior roots and it is in tabes invariably spared. The short tracts that radiate into the pos- terior horns from the posterior roots are entirely lost (compare normal section Plate 44, 1), Clarke's columns in consequence of the loss of fibres appear as clearly differentiated round white areas. Fig. 2.— Section through the Upper Lumbar Cord of Another Case. The degeneration is limited to symmetrical fields of both pos- terior columns, between which a small district is preserved (oval field, fo). In addition there is a so-called "border degenera- tion" in the borderland between the anterior and lateral columns. Principally the short descending tracts, which arise from the cells of the gray substance (central neurons) , are degenerated. Fig. 3. — Section through the Lower Lumbar Region of a Third Case. Aside from the equal clearing to be seen in the posterior col- umns (ventral fields normal) , the degeneration of the posterior roots (ip) is clearly recognizable, while the anterior (ra) are colored black and appear normal. 85 Explanation of Plate 74. Tabes Dorsalis. Fig. 1. — Section through tlie Cervical Cord of the Case Plate 73, Fig. 1. The continuation of the long ascending posterior root fibres of the lumbar cord, forming the column of Goll, is totally degener- ated. In Burdach's column there is likewise an area of lighten- ing in the middle zone (long fibres from the dorsal and cervical cord roots) . The medullary bridge at the apex of the posterior horns (L, column of Lissauer) which contains the most lateral fine root fibres is degenerated. The preparations are from a man, 50 years old, who for six years complained of distressing sensitiveness in the region of the stomach, which later became a girdle feeling about the entire abdomen. During the last four years there was increasing un- certainty of gait, frequent attacks of neuralgiform pain in the legs (lancinating pains) . Paresthesia?. In addition there was loss of the patellar reflex and of the pupillary light reflex, severe ataxia of locomotion, distinct disturbance of sensibility (delayed pain sense), disturbance of the bladder. Later there developed a chronic swelling in the left knee joint (tabic arthropathy), curved knees, and the ataxia became so severe that he was com- pletely bed-ridden. Fig. 2. — Section through the Cervical Cord of a Case of so-called " High Tabes. " In addition to the disease of the peripheral sensory neurons of the lower extremities, those for the upper extremities are like- wise very much diseased, and it is thus that the entire posterior columns are degenerated in the cervical cord (Goll's and Bur- dach's columns). There is, furthermore, an asymmetrical dis- ease of the lateral pyramidal tracts (slight lightening in the same) . We have here, therefore, a combined tabes. Fig. 3. — Section through the Upper Cervical Cord. Case of Com- bined Tabes. In this case, also a "high" tabes, a portion of the posterior columns, the posterior outer field, is preserved. In addition there is a distinct bilateral degeneration of the lateral cerebellar tracts (tabes combine) . Clinically in this case there was strik- ing muscular paresis and preservation of the pupillary reflex ! It was nevertheless looked upon as a possible case of "pseudotabes. " 86 Tafel 74. Fig. 1. Fig. 3. Tafel 75. Explanation of Plate 75. Spastic Spinal PARALYSIS. The preparations are from an extremely interesting case, which Professor Stri'impell has published recently. It is the only case of purely spastic spinal paralysis which is clearly explained anatomically. (This form has been postulated on theoretical grounds for years by Charcot and Erb.) A woman, 63 years old, sick for about two years with gradually increasing weakness of the legs and arms. The paresis gradually increased to complete par- alysis of the legs and arms, the muscles became rigid, allowed of but slight passive motion, spastic resistance, lively reflexes. No muscular atrophy, no disturbance of the bladder or of sensibility. Eventually (three years after) entire paralysis of the voluntary skeletal muscles (eye, face, masticatory, tongue, neck, arm, trunk, leg muscles). All the others normal. Anatomically there was found symmetrical degeneration of the pyramidal tracts in their entire course from the cortex of the brain through the internal capsule (see Plate 57, 6), the brain stem, the medulla, and spinal cord (central motorial neuron complex). Fig. 1. — Section through the Medulla. Both pyramids are degenerated, pale, a greater part of their nerve fibres have disappeared. Eig. 2. — Section through the Cervical Cord. Degeneration of both pyramidal tracts. In addition there is a slight cell atrophy in the anterior horns. (Ap- proaching amyotrophic lateral sclerosis.) Fig. 3. — Section through the Middle Dorsal Cord. A lightening in the lateral pyramidal tracts. Fig. 4. — Section through the Lumbar Cord. Same condition as in 3. The diseased pyramidal tracts have approached the periphery. Explanation of Plate 76. The Combined System Diseases. Besides combined tabes there are other cases in which there occurs not only disease of neuron complexes which stand in anatomical or functional relationship, but in which simultaneous primary degeneration of neuron complexes of different function takes place. The point of origin of the degenerative processes (primary disease of the neuron cell? neuron process?) is not yet definitely known. Clinically these cases present a slow, progressive, spastic paresis of the legs, arms, and also ataxia of the same, combined with more or less clearly demonstrable disturbance of sensibility and of the bladder. No mus- cular atrophy. Such a disease, for instance, is heredi- tary ataxia (see text). The following are sections from the spinal cord of such a case : Fig. 1. — Section through the Cervical Cord. Symmetrical disease of the lateral pyramidal and the anterior pyramidal tracts, and of the lateral cerebellar tracts of Goll's columns, and of the middle district of Burdach's columns. Fig. 2. — Section through the Loiver Dorsal Cord. As in section 1, in the posterior columns the degener- ation is less extensive and involves more the middle part of the posterior columns. Fig. 3. — Section through the Lumbar Cord. The lateral pyramidal tracts very severely degenerated; in the posterior column only a very small area of light- ening. 88 Tafe] 76. I %■ 3. w^»~ ^^r- * f- •..:•>;•:: Tafol 77. Explanation of Plate 77. Degeneration of Peripheral Nerves. Fig. 1. — Ascending Secondary Degeneration in the Sciatic Nerve after Amputation of the Leg. A man fourteen years previously had suffered amputation of the leg. The figure shows the boundary of a nerve bundle, in which the larger part of the nerve fibres has disappeared, espe- cially the coarser fibres are degenerated secondarily in an ascend- ing direction (the result of loss of function caused primary neuron-cell disease in the lumbar cord?) ; the finer are somewhat better preserved. (Compare with the normal transverse section, Plate 46, 3.) Fig. 2. — Descending Degeneration of the Bight Optic Nerve after Destruction of the Left Lateral Geniculate Body and the Bight Cor- pora Quadrigemina. In the optic nerve pass fibres the greater part of which have their neuron cells in the retina alongside of those which have their cells in the so-called subcortical optic centres. These last degen- erate in a descending direction, the others in an ascending. We recognize here a transparent sector- shaped area (x) in the optic nerve. (Compare with the normal optic nerve, Plate 46.) Fig. 3. — Compression Neuntis of the Optic Nerve. A case of acromegaly which had a malignant tumor of the hypophysis, which latter surrounded the optic nerve and caused partial degeneration (x, x) . v, sheath of the optic nerve (dural sheath). Fig. 4. — A Motor Nerve Branch in Spinal Muscular Atrophy. One readily sees the considerable loss of fibres widely diffused. (Belongs to the case from which Plate 72, 3 is prepared.) Fig. 5. — Posterior Boot from the Lumbar Cord in a Case of Tabes. (Belongs to the case, Plate 73, 3. ) The bundle which is repre- sented (x) is from the posterior root and contains scarcely ten normal fibres ; to the right of it the fibres are somewhat better preserved. V, blood-vessel. Fig. 6. — Bundles of the Peroneal Nerve from a Case of Neural Muscular Atrophy. One recognizes the loss of nerve fibres in focal areas, especially in the district of the middle bundle. Involve- ment of the spinal cord is not excluded (motor anterior-horn cells?). 89 Explanation of Plate 78. Multiple Neuritis. Figs. 1 and 2. — Preparations from Severe Cases of Alcoholic Neu- ritis (lfrotn the Crural Nerve, 2 from the Sciatic). A man, 40 years old, heavy drinker, was taken sick rather acutely with general weakness of the extremities which rapidly became complete paralysis. Great sensitiveness on pressure over the nerve trunks, loss of patellar reflexes, disturbances of sensi- bility, rapidly developing muscular atrophy. Strychnine injec- tions made his condition worse. Presence of psychical disturb- ance. Death after two and one-half months. An advanced degree of destruction of nerve fibres in all the peripheral nerves was found. In many bundles but from six to twelve (see Fig. 2) normal transverse sections of nerves are to be seen (compare Plate 46, 2) . This degeneration extended up as far as the anterior roots of the spinal cord. Fig. 5. — Transverse Section of the Cervical Cord of this Case. One recognizes the uncommonly distinct atrophy of the an- terior roots in their passage through the antero-lateral tracts (ra) ; there can be seen also in the anterior horns a perceptible lightening, particularly in the middle portion (m), which is secondary to the degeneration of the anterior roots which enter here. In Goll's columns slight ascending degeneration (long fibres of the posterior roots) . Fig. 3. — Post-Diphtheritic Neuritis. Cross section of a bundle from the crural nerve showing high degree of fibre degeneration. Taken from a 15-year-old boy, who, after convalescence from a severe pharyngeal diphtheria, developed acute pharyngeal paralysis and shortly afterward paralysis of the extremities. Patellar reflexes were lost within ten days, slight pain and disturbances of sensibility. Death from paralysis of the vagus. Fig. 4. — Longitudinal Section of a Nerve Bundle from the Sciatic Nerve of a Patient with Infectious Multiple Neuritis {Landry's Paralysis) . In a part of the degenerated nerve fibres are seen the products of cell destruction (little balls of myelin) which have not been transported away. The nerve fibres are found in all conceivable stages of degeneration. The preparation is from a case in which the cause of the dis- ease was unfathomable. A woman, 30 years old, sudden severe sickness (fever?), complete paralysis first of tbe legs, then soon after of the arms (ascending paralysis). The patient soon be- came unconscious, was very much neglected for the first two day, but death came while under treatment by a physician. (Spinal cord not examined. ) 90 Tafcl 78. Fig. 5. SECTION I. Morphology of the Nervous System. (Plates 1 to 10. ) The nervous system of man consists of (1), the cen- tral organ (brain — spinal cord) with the peripheral nerves that spring from them; and ("2), the sympa- thetic nervous system, consisting of a chain of sym- pathetic ganglia and their fibre ramifications. These two divisions are closely connected with each other by means of numerous nerve tracts. The brain and spinal cord lie in a bony capsule or protective framework, the cranial cavity and the spinal canal, from out of which the peripheral nerves pass to the soft parts. The sympathetic chain of ganglia lies on both sides of the vertebral column and immediately in front of it. The brain and spinal cord are surrounded by three membranous envelopes, the meninges. The outer one, lying immediately beneath the bone and serving as periosteum in the cranial acvity, is called the dura mater. It is a firm, dense, fibrous membrane. It surrounds the brain and spinal cord like a sac and covers also the outgoing nerves as far as their canals of exit where it ends, blending intimately with the margins of the foramina through which the nerves pass. In the dura course the broad collective chan- nels for the venous blood of the brain, blood which 1 2 ATLAS OF THE NERVOUS SYSTEM. flows into the internal jugular vein from the sinus venosi (sinus falciform, superior, inferior, cavernosus, petrosus, transversus, etc.). Prolongations of the dura pass into the interior of the skull cavity. The vertical portion of the dura that passes from above downward in the sagittal median line is adherent anteriorly to the crista galli, great falciform process (sickle process), which di- vides the skull cavity in the upper half into two parts. The transversely coursing tentorium serves as a roof for the posterior cavity of the skull. The dura surrounds the brain and spinal cord loosely, and beneath it is found a space filled with lymph, which is known as the subdural lymph space. The second envelope is a thin, cobweb-like cover- ing, the arachnoid. It is in close apposition to the brain, but less so to the spinal cord ; it bridges over the depressions in the brain without sinking into them. The Pacchionian bodies on each side of the falciform process are structurally connective-tissue constituents of the arachnoid. Under the arachnoid is the subarachnoidal lymph space, containing cer- ebro-spinal fluid, consisting of numerous compart- ments which communicate one with another. The most internal envelope, the pia mater, in conjunction with the arachnoid form what are usually called the "meninges." The pia dips into all the fissures and depressions of the brain in close contact with the nerve substance. The inward prolongations into the depressions are known as tela choroidea. It trans- ports the proficient vascular supply of the brain and spinal cord. The brain consists of two hemispheres and the MORPHOLOGY OF THE NERVOUS SYSTEM. 5 brain stem. The direct continuation of the latter portion is the spinal cord. The latter passes nearly perpendicular to the position of the former, owing to the fact that the brain stem below bends downward at an angle of nearly 90°. The weight of the fully developed brain varies from 1,300 to 1,400 grammes. The two hemispheres, which are connected one with another only on their median surfaces, consist of a superficial enveloping gray substance, the corti- cal substance, cortex cerebri, and of a central white mass beneath the cortex, the medullary substance. The cortex does not spread itself smoothly over the medullary substance of the hemispheres ; on the con- trary, following the formation of the numerous sulci it is arranged in worm-like gyri or convolutions. It is to this arrangement that the greater area of the gray matter is due. Of the convolutions, one part is constant while the other depends on individual variation. Each hemi- sphere is made up of various lobes; each lobe com- prises several cortical convolutions and one portion of medullary substance. In the anterior part of the cranial cavity lie the frontal lobes, constituting the anterior pole of the brain. They have two principal fissures, superior and inferior frontal sulci, which divide the frontal lobes into three convolutions, the superior, the mid- dle, and the inferior frontal gyri. Behind the frontal lobes, somewhat posterior to the middle of each hemisphere, passing from posteriorly above to anteriorly below, is a deep sulcus, the cen- tral fissure of Rolando. It separates the two central 4 ATLAS OF THE NERVOUS SYSTEM. convolutions, the anterior central gyrus and the pos- terior central g3 T rus. Behind the central convolutions lies the parietal lobe, which is divided by the inter- parietal sulcus into the superior and inferior parietal lobes. On these lobes border the occipital lobes, constitut- ing the posterior pole of the brain. They are sub- divided like the frontal lobes into three convolutions — the superior, middle, and inferior occipital gyri. The basilar surface of the occipital lobes rests upon the tentorium. The temporal lobes lie toward the middle of the cranial cavity. They have three fis- sures, the superior, middle, and inferior temporal sulci; and three convolutions, the superior, middle, and inferior temporal gyri. The temporal lobes in front and above are separated from the frontal and central convolutions by a very deep broad fissure, the fissure of Sylvius, which posteriorly passes directly into the inferior parietal convolutions. It thus gives rise to three arciform convolutions which in the in- ferior parietal lobe are known, enumerating from in front backward, as the supramarginal gyrus, the angular gyrus, and the preoccipital gyrus. At the bottom of the Sylvian fissure lies a lobe covered over by the neighboring convolutions, especially by the temporal and central lobes. This lobe is composed of a number of small convolutions and is known as the island of Reil. The convolutions that have thus far been consid- ered are on the external convex surface of the hemi- spheres. On the median surface are found in front the upper continuation of the superior frontal convo- lutions. The central convolutions unite in the para- MORPHOLOGY OF THE NERVOUS SYSTEM. 5 central lobes and the parietal lobes continue as the praecuneus. The latter is separated from the median surface of the occipital lobe by the parieto-occipital fissure. The median surface of the occipital lobe is divided into the cuneus above and lingual lobe be- low, separated by the calcarine fissure. On the under surface of the temporal lobes, the median portion of the occipito-temporal gyrus bor- ders on the inferior temporal gyrus, and separated by the occipito-temporal fisssure lies the inferior margi- nal convolution, the gyrus hippocampus, which ends anteriorly as the uncus. On the base of the frontal lobes, the fissures of importance are the straight sulcus and laterally to this the tri-radiate sulcus, to which belongs the middle frontal gyrus. Aside from the above-mentioned convolutions on the median surface of the hemisphere there are other relationships to be considered. The cortex terminates superiorly as the gyrus fornicatus and below as the gyrus hippocam- pus (superior and inferior marginal convolutions). Beneath the superior marginal convolution the white substance breaks through both parts, unites and con- stitutes the corpus callosum. Above the inferior marginal convolution the white medullary substance passes out of the two hemi- spheres converging as in the corpus callosum and uniting to form a part of the brain stem at its begin- ning (crusta). Between the corpus callosum and the cerebral peduncles are a number of formations and spaces which will be considered later on. Here it only re- mains to call attention to the fact that the entire middle portion named, bordering upon the marginal 6 ATLAS OF THE NEKV0US SYSTEM. convolution, has no longer a covering of cortical sub- stance. The corpus callosum, which connects the two hemi- spheres, is made up of thick layers of white sub- stance. Its larger, middle portion passes in a nearly horizontal direction. The anterior part, the knee of the corpus callosum, bends basalward and just be- fore its termination somewhat backward. The pos- terior end thickens into a cushion-like prominence and is known as the splenium of the corpus callosum. In the interior of each hemisphere is found a mass of white medullated substance, constituting the core of the various lobes of the hemispheres as previously described. In its upper half, up to the level of the corpus callosum, this mass of white substance is formed by the radiation of fibres from this structure. As shown in cross section at this level, it is called the centrum semiovale of Vieussens. In its basal portion there is seen embedded in the medullary sub- stance a grayish-red mass the size of a goose egg. This constitutes the root ganglion of the brain — the corpus striatum. It is divided into the lenticular nucleus, situated laterally ; and the caudate nucleus, situated mesially. This separation is produced by a white tract passing through this region from the cortex of the various cerebral lobes. It emerges from the base of each hemisphere as the crusta. In the interior of each hemisphere is a system of cavities filled with lymph, the lateral ventricle (ven- tricul. lateral.). The roof of each lateral ventricle is formed by the median half of the centrum semiovale of that side, and because of this circumstance it is here known as the tegmentum of the ventricle. The MORPHOLOGY OF THE NERVOUS SYSTEM. 7 basal ganglia, under the name of the corpus striatum, pass out of the medullary substance as a free surface and project outward and below into the lateral ven- tricles. The part of the lateral ventricle that is situated be- tween the under surface of the lateral portions of the corpus callosum above and the basal ganglia below is known as the middle cell (cellula media) . The ventri- cle from here extends by its anterior horn (cornu an- terioris) into the anterior lobe, by its posterior horn (cornu posterioris) into the occipital lobe, and by its inferior horn (cornu inferioris) into the temporal lobe. The anterior and posterior horns are entirely sur- rounded by the white substance of the hemisphere. The inferior horn, on the other hand, is not closed in the median line (inferior aperture). This results from an involution and contraction of the inferior marginal convolution, which forms in consequence a cushion or pad-like projection into the inferior horn, known as the cornu Ammonis. The exact end of the cortex of the gyrus hippocampus forms the small gyrus dentatus (fascia Tarini). This relationship is well seen in the section, plate 27. From the free end of the cornu Ammonis arises the medullated fimbria, forming the termination of the white substance of the gyrus hippocampus. It passes along with the superficially indentated Am- nion's horn " digitationes corpus Ammonis" from the anterior end of the inferior horn backward and up- ward. At the point of divergence of the inferior horn from the cella media, the fimbria separates from the cornu Ammonis, uniting with its fellow of the op- posite side as the ascending pillars of the fornix 8 ATLAS OF THE NERVOUS SYSTEM. "crus ascendens fornicis," converging toward the inferior surface of the posterior portion of the corpus callosmn, and thus forms in the middle a triangular space, the psalterium. The united fornix passes be- neath the corpus callosmn and unites with it some dis- tance forward. It divides, however, before it reaches the genu of the corpus collosum and again descends as the two descending pillars of the fornix. At the base the descending crura of the fornix turn back- ward and terminate in the bilateral mammillary bodies. Between the knee of the corpus callosum and the descending pillars of the fornix there remains in the middle, in consequence of the relations already de- scribed, a free space which is filled out b} 7 " two small partitions, the septa pellucida, with a small cavity lying between, the ventricle of the septa pellucida. To the side of each septum lies the lateral ventricle beneath the corpus callosum. From the floor of each lateral ventricle, passing up abruptly out of the medullated substance of the hemi- sphere, there projects into the ventricle the free upper surface of the corpus striatum. Its anterior broader portion, extending toward the anterior horn, is called the head of the corpus striatum (in section nucleus caudatus). From the head there passes backward and outward the small tail of the latter, which bends downward at the place of departure of the inferior horn and finally continues forward from here as a portion of the roof of the inferior horn. In a direction median to the corpus striatum runs a small white band parallel with it, the stria cornea. It separates the corpus striatum from a structure that MORPHOLOGY OP THE NERVOUS SYSTEM. 9 rises posterior and median to the corpus striatum, the optic thalamus, a mass which on cross section ap- pears like the basal ganglion of a reddish-gray color. The two thalami approach each other posteriori}' and somewhat toward the median line. The cavity between them is the third or middle ventricle. The lateral ventricles of the hemispheres, particularly the cella media, are in direct connection with the third ventricle by means of a small aperture immediately behind the descending pillars of the fornix, the fora- men of Munro. The fornix with the corpus callosum lying above it would constitute the roof of the third ventricle were it not that from the pia mater beneath the splenium corporis callosi (transverse fissure) a process of this membrane projects into the third ven- tricle, which in this locality is open. This vascular projection of the pia passes beneath the fornix cover- ing the third ventricle and spreads out thinly anteri- orly as the tela choroidea superior. It carries in its central portions two band-like, granular-looking struc- tures, plexus chorioidei medii. These pass through the foramen of Munro out of the third ventricle into the lateral ventricles as the plexus chorioidei late- rales. In the lateral ventricles they pass backward resting on the lateral border of the thalamus, finally turning about into the inferior horn. Here they hang together with the pia, which has pressed in through the aperture in the inferior horn. As described above, the white substance of the hemispheres is compressed in the middle portion of each hemisphere owing to the gray masses of the basal ganglia and of the optic thalamus, which take their origin in that locality (the middle part) and 10 ATLAS OF THE JSTERYOUS SYSTEM. increase in extent toward the base of the hemispheres. The medullary tracts which pass out of the centrum semiovale deeper down break through the basal gan- glion as the anterior limb of the internal capsule and thereby divide the lateral lenticular nucleus in the direction of the insular lobe from the nucleus cauda- tus. Another portion of the white substance of the hemispheres passes downward as the posterior limb of the internal capsule between the lenticular nucleus and the optic thalamus. Both limbs come into con- tact at the knee of the internal capsule. The constit- uents of the medullary substance of the internal cap- sule pass in part into the basal ganglia and optic thalamus, disappearing therein; in part they con- tinue in the internal capsule further toward the basal region and make their exit as the crusta from the hemispheres at the base of the brain. The wedge-shaped lenticular nucleus which forces itself between the internal capsule and the lobes of the island of Reil divides into several parts, a lateral, larger putamen, and several internal portions, which lie in a median direction. These are from a devel- opmental point of view to be distinguished from the putamen. They are called globus pallidus. The putamen and the nucleus caudatus together comprise the actual basal ganglion. Lateral to the putamen the white substance of the hemisphere is continued inferiorly as the narrow external capsule. Between this and the medullated substance of the lobe of the insula lies another small gray mass running parallel to the island, the claustrum. The medullary sub- stance of the hemispheres, which, as has already been described, is compressed into small bands (cap- Morphology of the nervous system. ii sula interna and externa), increases again in extent below the lenticular nucleus, especially in the pos- terior direction where it constitutes the medullated substance of the temporal lobe. Another small, round, gray mass, the nucleus amygdalae, is found embedded in the medullary substance at the base of the brain below the anterior portion of the lenticular nucleus between the frontal and temporal lobes. After removal of the corpus callosum with the for- nix and tela choroidea the thalamus opticus lies with its upper and median surface free. It exhibits an- teriorly a little elevation, tuberculum anterior, and expands posteriorly as the pulvinar. The median surfaces of the thalami constitute the lateral walls of the third ventricle. Passing along the upper inner edge of the thalami extends the small tenia medullaris (semicircular is), rising up from below, converging posteriorly as the pedunculus conarii, and decussating with the peduncule of the other side. Laterally to the place of decussation lies on both sides the small ganglion habenulse. The decussation has no connection with the pineal gland, a structure of about the size of a hazelnut (epi- physis conarium, glandula pinealis). Three short commissural bands run transversely across the space of the third ventricle between the two sides. Imme- diately in front of the descending peduncles of the fornix, deeply placed, is the large white anterior commissure. Through the middle of the third ven- tricle passes the soft lacerable gray commissure, and immediately under and in front of the decussating pedunculi conarii is found the posterior commissure. Below the thalamus, on both sides of the brain, lies 12 ATLAS OF THE NERVOUS SYSTEM. a region into which a portion of the medullary sub- stance enters from the lenticular nucleus, optic thala- mus, and internal capsule, the so-called subthalamic region. In it lies the oval subthalamic body and the beginning of the red nucleus, the main portion of which is situated more caudad in the brain stem. The third ventricle terminates anteriorly between the two descending, somewhat diverging limbs of the fornix. Inferiorly it narrows like a funnel to the in- fundibulum, the termination of which is made by the hypophysis cerebri in the sella turcica of the sphe- noid bone. Posteriorly the ventricle becomes shal- lower in consequence of the median surfaces of the thalamus, whose lower portions converge gradually and continue beneath the posterior commissure. This closes in the ventricle from above and forms a narrow canal, the aqueduct of Sylvius. While the lower halves of the thalamus unite, the upper halves are pressed apart in their caudal portion by the corpora quadrigemina. These bodies take their origin behind the posterior commissure. They are divided into the two anterior and the two posterior portions — the anterior and posterior quadrigeminal bodies. Lat- erally from the corpora quadrigemina pass the two arms (brachia) , the brachium anterior and posterior, to the two geniculate bodies, the lateral and median, which lie between the corpora quadrigemina and the pulvinar. From the lateral geniculate body the white optic tract passes toward the base of the brain. In front of the broad pontal fibres the white cere- bral peduncles converge. In the space between the crura cerebri is the posterior perforated substance, in front of which are two white bodies about the size of MORPHOLOGY OF THE NERVOUS SYSTEM. 13 peas, the mammillary bodies or corpora candicantia. In front of these is the continuation of the third ven- tricle, the infundibulum with the hypophysis. In front of the latter is the chiasm of the optic nerves, made up of the continuations forward of the optic tracts of the two sides after they have rounded the cerebral peduncles. Beneath the corpora quadri- gemina the system of cavities continues as the aque- duct, the walls of which are composed of the central ventricular gray substance which line the third ven- tricle, covering the surface of the thalami. Beneath the corpora quadrigemina lies the teg- mental region, which is formed from the subthalamic region by the junction of the thalami. Basal to the tegmentum are found the converging crura cerebri, which emerge from the two hemispheres and which seem to be the continuation of the white substance of the internal capsule. Beneath the tegmentum they form the crusta. Between the tegmentum and the pes lies a brownish, half -moon-shaped mass, the substantia nigra. Behind the corpora quadrigemina is the cerebellum, thrusting itself, covered by the tentorium, beneath the occipital lobes, into the pos- terior cranial fossa. In the median line and between the two cerebellar hemispheres lies the worm (vermis). Beneath the corpora quadrigemina the brachium conjunctivum (processus cerebelli ad corpora quad- rigemina) passes from the tegmental region into the cerebellum. Between these the thin anterior medul- lary velum forms with the lingula, the direct passage to the vermis (the valve of Vieussens). The aqueduct passes beneath the valve of Vieus- sens and spreads out into the fourth ventricle bounded 14 ATLAS OF THE NERVOUS SYSTEM. Fig. 1. by the diverging superior cerebellar peduncles. The accompanying Fig. 1 illustrates the connections of the ventricular system. The floor of the fourth ventricle constitutes a part of the fossa rhomboidalis. Beneath this are continued the component parts of the me- dulla oblongata. They are con- tinued from the tegmentum and pes of the crura cerebri. The roof of the fourth ventri- cle is formed by the under portion of the worm (vermis inferior). A process of the pia, known as the tela choroidea inferior, enters into the ventricle from 'behind. The hemispheres of the cere- bellum are composed, like those of the cerebrum, of the superficial gray cortex, and the central white medullary substance. They are divided into innumerable small, generally parallel convolutions which are arranged in single lobes. Every lobe is in continuous connection with the cor- responding portion of the other hemisphere by means of a part of the vermis. On the upper surface are two hemisphere lobes, the lobus superior, anterior and posterior (semilunaris), both united by the superior vermis (lobus centralis, monticulus, folia cacuminis). On the under surface are found, enumerated from in front, the following hemisphere lobes: flocculus, tonsilla, lobus cuneiformis, posterior inferior lobe (semilunaris). The inferior vermis supplies the connection of these lobes (nodulus, uvula, pyramis, MORPHOLOGY OF THE NERVOUS SYSTEM. 15 commissura brevis, are the several components in re- spective order). In the interior of the medullated area of the cerebellar hemispheres lies a gray puck- ered substance, the corpus dentatum cerebelli, and in the medullary area of the vermis the nucleus teg- menti (roof nucleus). Other smaller gray masses, emboliformis nucleus and globosus, lie between these two. From the medullary substance of the cerebellum the superior cerebellar peduncles already described converge anteriorly, while inferiorly passes the pro- cessus cerebelli ad pontem, composed of white medul- lated bundles which converge posteriorly over the descending cerebral peduncles and at the base of the brain form the pons (pons Varolii). In a posterior direction run convergingly the processus cerebelli ad medullam oblongatam or the restiform bodies. The superior cerebellar peduncles form the lateral bound- aries of the anterior half of the rhomboid fossa, the restiform bodies form the posterior half. The shape of the rhomboid fossa is determined by the conver- gence of these two medullary tracts as they pass from the cerebellum. The fourth ventricle is covered with a layer of gray substance (central gray matter), and in the middle of the cavity the medullary white substance of the striae acusticse pass transversely toward the two sides at an obtuse angle. Beneath the gray matter lies the continuation of the constituents of the tegmentum ; beneath this, the continuation of the crusta encircled and divided by the transverse pontal fibres of the cerebellum. In addition to this there is a number of small gray 10 ATLAS OF THE NERVOUS SYSTEM. masses (nuclei) lying between all of these interlaced medullary pathways. All of these together with the nerves that pass out constitute the medulla oblongata. On the posterior border of the pons, at the base of the brain, pass the pyramids, the continuation of the crusta. Laterally to the pyramids in the medulla are the olivary bodies which on cross section appear as variously involuted puckered gray leaves. Dorsally to the passage of the pyramids the fourth ventricle becomes narrower, owing to the converging restiform bodies which unite at an acute, angle the calamus scriptorius. At the most posterior portion of the angle the ventricle sinks deeper into the sub- stance of the medulla and soon disappears entirely from the surface, lying toward the centre of the medulla as the central canal and continuing in this position throughout the entire spinal cord. The medullated bundles of the restiform bodies, shortly before their junction, form into a median bundle, the funiculus gracilis, or Goll's column, and a lateral bundle, the funiculus cuneatus, or column of Burdach. Both of these continue seemingly unin- terrupted throughout the cord as the posterior col- umns. Ventrally the pyramids approach one an- other at the surface, while deeper in the medulla they may be seen to constitute the motor crossing (decussation of the pyramids). In conjunction with the most ventral portion of the restiform bodies, which does not go to the posterior columns, these crossed pyramidal fibres form the lateral columns or tracts of the spinal cord (funiculus lateralis). The anterior columns (funiculus anterior) arise from the parts that lie under the pyramids and MORPHOLOGY OF THE NERVOUS SYSTEM. 17 which come into view after the disappearance of the latter. Around the central canal, in the centre of the spinal cord, there are grouped together as a continuation of the gray substance of the ventricles with its nuclear masses, the anterior and posterior horns. The gray substance is, therefore, like the ventricles, pushed toward the centre, while the white substance lies on the periphery. The medulla oblongata is thus trans- formed into spinal cord. The spinal cord consists of a round white bundle about the size of the little finger. It is enclosed in its membranes and extends in the spinal canal as far as the upper border of the second lumbar vertebra. It gradually diminishes in size as it passes down- ward, but there are developed in its course two en- largements, one in the cervical and one in the lumbar portion. These enlargements result from a marked increase in the central gray matter of the anterior and posterior horns. Between these two enlarge- ments lies the dorsal portion of the cord. The lower termination of the cord is known as the conus medul- laris. The three columns, the anterior, lateral, and posterior, pass, as portrayed above, circumscribing the gray substance of the anterior and posterior horns. In the conus medullaris terminate the columns and horns of the cord. In the conus the lateral column is the most, the anterior column the least prominent. In this portion of the cord the gray substance pre- dominates over the white ; iu the cervical cord, etc. , the reverse is the case. Between the two anterior columns runs the deep anterior longitudinal fissure. Between the two pos- 2 18 ATLAS OF THE NERVOUS SYSTEM. terior columns is the narrow posterior longitudinal fissure. From the stem of the brain and from the spinal cord the peripheral nerves pass out. They are the continuation of medullary columns gathered together in bundles. The nerves are divided into the twelve cranial, and the thirty-one pairs of spinal nerves. At the base of the brain the twelve cranial nerves, up to the fourth, take their origin in the following order : I. The olfactory nerve. It is composed of the small numerous nervi olfactorii which pass through the lamina cribrosa of the ethmoid bone. These enter into the olfactory bulb, which lies in the straight sulcus (sulcus rectus) of the frontal lobe. The bulb passes posteriorly as the olfactory tract and terminates laterally in front of the chiasm in the tri- gonum olfactorium. The olfactory tract, etc., in man comprises an undeveloped portion of the brain, but in the lower animals it is for the most part de- veloped into a very considerable cranial lobe. II. Optic nerve. Both nerves pass from the eye- balls and converge to the chiasm, undergo partial de- cussation (nasal, most considerable bundle) and pass as the optic tract over the cerebral peduncles farther upward as far as the lateral geniculate bodies in which they seemingly disappear. III. Motor oculi. It passes beneath the quadri- geminal bodies in many bundles, through the sub- stance of the tegmentum and reaches the surface mesal to the peduncle at the anterior border of the pons. IV. Trochlear nerve. It passes dorsally behind the posterior quadrigeminal bodies, totally decus- MORPHOLOGY OF THE NERVOUS SYITEM. 19 sates in the velum medullare, passes toward the base and then over the peduncles farther forward. V. Trigeminal nerve. It passes out with an an- terior (motor) and a posterior (sensory) root through the lateral fibres of the pons. The posterior root forms the Gasserian ganglion. Then the nerve divides into its three branches. VI. Abducens nerve. It arises from the floor of the fourth ventricle, passes through the medulla, and passes out at the posterior border of the pons lateral to the pyramids. VII. Facial nerve. It emerges in company with the following nerve externally from the olive at the posterior border of the pons. VIII. Auditory nerve. It is composed of two roots, the vestibular nerve (anterior modian root) and the cochlear nerve (from the cochlea) (posterior lat- eral root) and emerges with the facial. IX. Glosso-pharyngeal nerve. X. Vagus nerve. Both of these pass out together ventral to the restiform bodies in many roots. The first forms with others the petrosal ganglion; the second the jugular ganglion. XI. The spinal accessory nerve. It emerges by many roots that pass out through the lateral columns from the upper cervical cord and medulla. Its inner branch goes to the pneumogastric. XII. Hypoglossal nerve. It passes out in many bundles between the pyramids and the olive. The spinal nerves are divided into the eight cervi- cal, the twelve dorsal, the five lumbar, the five sacral, and the one (seldom two) coccygeal. Each arises from an individual spinal cord segment; conse- 20 ALTAS OF THE NERVOUS SYSTEM. quently from the eight cervical, twelve dorsal, five lumbar segments, etc. Every nerve emerges from its spinal segment in two separate portions — "roots." Between the anterior and lateral columns emerge the anterior motor root (radix anterior) ; between the lateral and posterior columns the posterior (sen- sory) roots (radix posterior). Both roots unite into one nerve trunk. Before uniting with the anterior root the posterior root forms the intervertebral ganglion, a knuckle-shaped swelling in the inter- vertebral foramina. The nerves for the neck, the extremities, etc., comprise, before they pass into the soft parts through their numerous anastomoses, the nerve plexuses (plexus cervicalis, brachialis, lumbalis, sacralis, etc.). In the strict sense of the word the peripheral nerves arise primarily from the plexuses. Consequently the peripheral nerves are composed of mixed fibres from the anterior and posterior roots, not only of a single spinal segmental level, but of different levels. (For further details see Plate 23.) The nerve roots for the lower extremi- ties, in consequence of their level of origin (level of the first lumbar vertebra, see Plate 23) run for some distance together with the conus medullaris before their departure through the intervertebral foramina, and below the conus constitute the cauda equina. The chain of the sympathetic divides into a series of small prominences (ganglia) which from their beginning at the neck (cervix) (ganglion supremum, medium, imum) are situated at the anterior border of the vertebral column. In front of each vertebra lies a ganglion. These are united with one another by attenuated bands of nerves. Nerve fibres pass MORPHOLOGY OF THE NERVOUS SYSTEM. 21 also to the ganglion from the cranial nerves and the spinal plexuses. At the coccyx the sympathetic chain terminates in the median ganglion, ganglion impar. From the sympathetic ganglia pass the sympathetic nerves, partly following the blood-vessels, partly con- tinuing farther in the nerves of the cerebrum and spinal cord to the innervated organs (to all smooth muscle fibres) . ■ In part they form in the neighbor- hood of these organs other ganglia (heart-muscle ganglia, ganglia of the mesentery, stomach, etc.). The arterial blood-vessels of the brain take their origin from the internal carotid arteries and from the vertebral arteries and from the basal circle of Willis, which is formed from the anastomoses of these two (see Plate 5). From it arise the arteries which con- tinue their course in the pia — arteria corpus callosi (for the corpus callosum, median brain surfaces), artery of the fossa of Sylvius (for the environment of the ventricle and basal ganglia), arteria choroidea (for the ventricle), arteria profunda (for the occipital and temporal lobes, etc.). The blood-vessels of the brain substance are what is called terminal arteries, that is, they do not have such profuse connections through anastomoses that neighboring vessels may in case of necessity take their place. The arteries of the spinal cord arise in part from the vertebral artery as an- terior and posterior spinal arteries; but in part they proceed from the arteria} intercostales, etc. The vessels enter from all sides, especially, however, from the anterior longitudinal fissure. The accompanying illustrations show the divisions of the blood-vessels : Fig. 3 those of the fossa of Syl- vius (A.f.S.) to the basal ganglia and the internal 22 ATLAS OF THE NERVOUS SYSTEM. capsule (A.l.st. — arterialenticulostriata,w hich from a pathological point of view is one of the most im- portant branches). Fig. 2, a cross section of the spinal cord with its blood-vessels; one observes the vascular supply of the gray substance through the anterior sulcus artery. The return of the blood from the brain is accom- plished by means of the pial veins which empty in the venous sinuses (from the third ventricle, the vena magna Galeni), which in turn pour into the internal jugular. In the spinal cord the return circulation is acccom- tarotu wJ. Fig. 2. Fig. 8. plished by means of the richly anastomosing Breschet's plexus of veins which ramifies in the dura mater. The lymph tracts of the brain and spinal cord communicate with the lymph spaces which are dis- tributed throughout the meninges, the ventricular cavities being in open communication with the sub- arachnoidal space (liquor cerebro-spinalis). The nerves of the pia and dura are of sympathetic origin, a part of which (those for the dura) arise from the sensory divisions of the trigeminus. SECTION II Development and Structure of the Nervous System. (Plates 11 to 48.) The central nervous system develops from the outer blastoderm, the ectoderm of the embryonic primary constituent. In the middle of the embryonal area a couple of folds develop from the ectoderm in a longi- tudinal direction. These, coming together and dip- ping below, form the medullary groove. By the closing of the lateral walls of the primitive tracts, at the dorsal portion, the medullary canal is formed. From the layers of the epithelial cells of the neural canal is developed the matrix or foundation substance (glia) of the central nervous system and the nervous substance proper. The membranes and blood-vessels are of mesodermal origin. Latero-dorsal from the medullary groove itself there is formed a border studded with cells (gan- glion border or furrow), which runs alongside of the medullary channel, throughout its entire length. From the furrow arise the intervertebral ganglia and the analogous ganglia of the sensory cranial nerves, such as the olfactory ganglia, Gasserian ganglion, the jugular, cochlear, petrosal ganglia, etc. In the first embryonal month the medullary groove divides at its nasal club-shaped end into three pri- mary vesicles. These are the primary anterior vesi- 23 24 ATLAS OF THE NERVOUS SYSTEM. cle or fore-brain, which later divides into fore- and tween-brain, the primary middle vesicle, and the primary posterior vesicle dividing secondarily into the hind-brain and after-brain. These constitute therefore three, or after later subdivision five, cere- bral vesicles. From these develops the entire brain. The cavity of the medullary canal becomes the sys- tem of the ventricles, the walls of the canal and vesi- cles expanding into the structures of the spinal cord and brain. In the process of development the fore-brain is divided into two parts (the rudimentary cerebral hemispheres) by the falciform process of the dura which grows in from above and presses in the roof of the vesicle (pallium). Through their more rapid growth the hemispheres soon exceed in area the re- maining portions of the brain. The wall of the fore- brain vesicle expands to form the cortex and medul- lary substance of the hemispheres, while from its floor the primary constituent of the basal ganglia projects into the primary cavity, which has now be- come the lateral ventricle. Externally it adheres to the lateral wall (at the external capsule), but mesi- ally it remains free (the nucleus caudatus). The corpus callosum extends from the vesicles of the hemispheres on their median surfaces, bridges over the middle line, and unites the two hemispheres. The cortex, which at first is smooth, develops through involution (second to third month) its pri- mary fissures and convolutions, the fossa of Sylvius being the first to develop (see Plate 12). From the tween-brain arise the optic thalami and the remaining structures such as the hypophysis, DEVELOPMENT AND STRUCTURE. 25 conarium, tractus opticus, tractus olfactorius, etc., which surround the cavity that has been transformed into the third ventricle. The thalamus unites at the putamen with the most posterior portion of the basal ganglion. Here, therefore, the fore-brain is in re- lationship with the tween-brain. From the mid-brain develop the corpora quadri- gemina, tegmentum, and pes of the crura cerebri, while the cavity narrows into the aqueduct. From the hind-brain develops the cerebellum, and from the after-brain the medulla. A downward cerebral flexure, the pontine arch, is formed quite early in the mid-brain. Microscopic investigation of the central nervous system reveals its structure to be of two varieties of tissue: the matrix, glia, and the nervous substance contained in it, the nerve cells and fibres. Both de- velop in such wise from the ectodermal epithelial cells of the neural canal that a part of the same, the spongioblasts, increasing from the central canal, send "out numerous fibrils in all directions, forming a fine network and thus developing the glia (spider cells, astrocytes) . Cells of different structure, the neuroblasts, develop as germ cells, soon sending out a long, thick process and later numerous finer twigs. From them develop the ganglion cells and nerve fibres. Collections of such germ cells are found in certain definite portions of the central nervous system. Thus they are found in all the cortex of the cerebrum and cerebellum and in the basal ganglia, the latter being looked upon as modified cortex. Further they are located in the thalamus, in the corpora quadrigemina, etc., and 26 ATLAS OF THE NERVOUS SYSTEM. finally from the mid-brain in the neighborhood of the central canal as far down as the end of the spinal cord in an arrangement known as the " central nu- clear area." The remaining portion of the central nervous sys- tem is developed principally from the long processes of these cells. Collectively these form later the medul- lary substance, the "white" substance, whereas the aggregation of cells forms the " gray" substance. The complex "nerve cell with its accompanying nervous prolongations" in its entirety is designated a neuron (~o vedpov, nerve unit). The long prolongations of the ganglion cells of the cortex, basal ganglia, and optic thalamus run their course almost entirely within the central organ ; that is, they have their beginning and ending there, con- stituting central neurons. Those from the peri- canalicular nuclear areas grow in part from the cen- tral organ toward the periphery of the body and constitute peripheral neurons. The last-named com- prise the motor cranial nerves, which grow out of the mid- and hind-brain, and the motor spinal nerves which project from the ventral nuclear areas of the spinal cord (anterior horn). The latter develop as the anterior roots from the anterior horn, springing direct, as long processes, from the ganglion cells situated there. The arrangement of the sensory nerves is exactl}' reversed. These grow from the cells of the spinal ganglia into the dorsal nuclear area of the spinal cord (posterior horn, etc.) as the sensory spinal nerves. In a similar way the sensory cranial nerves grow into the brain from the cells of the Gasserian, petro- DEVELOPMENT AND STRUCTURE. 27 sal, cochlear, and jugular ganglia and from the cells of the retina and mucous membrane of the nose (ol- factory bulb, mid-brain, hind-brain). At the same time there pass out from these cells just mentioned other processes to the periphery which constitute the peripheral sensory nerves. This neuron consequently has its cell about in the middle of its course. In the course of development, the neuroblasts transform themselves little by little into ganglion cells. Their nervous processes may attain to a con- siderable length. From about the fifth month these nervous processes become surrounded with a sheath which accompanies them throughout their entire course, following the protal formation of the medul- lary sheaths. Every long process is surrounded with a soft white medullary sheath and becomes thereby a definite, functionating nerve fibre. Development of the medullary sheath occurs, vary- ing at different times for the different neuron-com- plexes, from the already named period of embryonal life to the age of childhood and beyond. Successively one portion of the processes after another becomes medullated. Thus results the well-known white color of the medullary substance. As a rule medul- lation occurs first in those parts that are the earliest to functionate. Thus the first to develop their med- ullary sheaths are the peripheral reflex tracts, the central sensory conducting pathway before the motor, and the projection fibres before the associa- tion tracts, etc. (see Plate 48). The fully developed neuroglia is made up of nu- merous small cells, supporting cells, glia cells. The enormous number of prolongations of these cells form 28 ATLAS OF THE NERVOUS SYSTEM. a fine fibrillar network in which are embedded the gan- glion cells and nerve fibres. The walls of the central canal and of the ventricles are lined with cylindrical epithelium (ependyma), the primitive epithelial cells of this area. The mature ganglion cells are in part large cells of different shape having well-marked nuclei and made up of protoplasm of very different structure, fre- quently impregnated with pigment. In part they are small nuclear cells consisting almost entirely of nuclear substance. From the cells there pass off small side prolongations which branch or divide near the cell as do the branches of a tree, and these are called dendritic or protoplasmic prolongations. The process which arises as the direct prolongation of the neuroblast and which has been considered above is known as the axis-cylinder prolongation. After its exit from the ganglion cell this axis-C3 T lin- der prolongation becomes ensheathed with medullary substance and is then known as a nerve fibre. The nerve fibre consists, therefore, of an axial core or thread, which in turn is composed of numerous individual fibrillse and the surrounding segmented medullary sheath. These nerve fibres pass out from the central neuron system as peripheral nerves and become covered with a second, very thin envelope around the medullary sheath, known as the sheath of Schwan, or the neurilemma. The axis-cylinder prolongation may be of various lengths, but it always terminates in an arborization, a splitting up of the fibres. Before this it gives off at different levels lateral branches known as collat- erals, which end likewise by splitting up, that is, by DEVELOPMENT AND STRUCTURE. 29 terminal ramification. The cells with long prolonga- tions (cells of Deiters' type) make up the preponder- ating majority, in contrast to those with the very short processes which have their terminal arborization close to the cell itself (Golgi's spindle cells). Ganglionic cells with their cell branchings, to- gether with their axis-cylinder processes and ter- minal arborizations, constitute anatomical and physi- ological units — the neurons. All nerve tracts are made up of a collection of such neurons. Direct anatomical continuity between neu- rons does not seem to exist.* They seem to be like the cog-wheels of a machine in which the axis-cylin- der termination of one neuron embraces the cell rami- fications of the other. The brain, the spinal cord, the peripheral nerves, and the sympathetic nervous sys- tem are made up entirely of such neurons. Transference of excitation from one neuron to an- other takes place through the occurrence of motion in these terminations. The conduction in the axis- cylinder prolongation is cellulifugal, in the cell rami- fications cellulipetal. No neuron is in individual rela- tionship to another neuron only, but to many neurons (intercalary cell neurons), a condition which is made possible by reason of the countless cellular ramifica- tions, and the giving off of numerous collaterals. The gray substance of the nervous system, the cortex, the ganglia, and nuclear deposits, consist of a groundwork of glia in which are embedded the gan- glion cells, their dendrites, and their more or less * In all probability there exists a neuron anastomosis be- tween protoplasmic prolongations. • 30 ATLAS OF THE NERVOUS SYSTEM. numerous nerve fibres which are partly medullated and partly non-medullated (white fibres of Remak). The white substance, the centrum semiovale of the hemispheres, corpus callosum, internal capsules, pe- duncles, columns of the spinal cord, and peripheral nerves consist merely of medullated nerve fibres, the medullary envelope being responsible for the color and consistence of the substance. The finer microscopical structure of individual parts of the central nervous system is to be found in the description of Plates 13 to 21 and is far more easy to comprehend from illustrations than from verbal description. To recapitulate briefly the inner relationships : In the cell layer of the cerebral cortex the medul- lary fibres of the centrum semiovale arise and end. They belong to three different systems. I. THE COMMISSURAL TRACTS. They constitute the greater part of the central me- dullary deposit as fibres of the corpus callosum and unite symmetrical localities in the convolutions of one hemisphere with those of the other. Those por- tions of the cortex that are not thus united through fibres of the corpus callosum, such as the basal, tem- poral, and occipital lobes, are connected by means of the deeply situated anterior commissure. II. THE ASSOCIATION TRACTS. These are made up of medullary tracts which con- nect different parts of the same hemisphere. Adja- cent convolutions are connected by the fibrse pro- DEVELOPMENT AND STRUCTURE. 31 price; distant convolutions and lobes by means of the short and long association bundles. They course within the hemispheres from convolution to convolu- tion and are mostly collected into definite bundles, which pass through the white substance to break up in the more distant ones. Some of these bundles have special names, such as the cingulum, fasciculus uncinatus, fasciculus longi- tudinalis inferior, etc. The latter unites the tem- poral lobes with the frontal and occipital lobes, while the superior longitudinal fascicle and subcallosus unite the temporal with the occipital lobes, etc. Por- tions of the temporal and occipital lobes are connected with especial closeness by numerous association fibres within their own territory and with the remaining portions of the cortex. III. THE PROJECTION TRACTS. These are the most important fibre tracts. They arise from all parts of the brain cortex, or end in the same, and pass between the transversely coursing commissural fibres and the longitudinally coursing association fibres further downward. They bring more deeply lying portions of the brain stem and spinal cord into connection with the cortex. The totality of these tracts is called the corona radiata. The tracts of the corona radiata are divided accord- ing to the locality of their axis-cylinder ramifications into short tracts and long tracts. The corona radiata tracts which come from all parts of the cortex are collected in the internal capsule in the anterior and posterior limbs, and pass further caudad. They thus break through the basal ganglia. 32 atlas of the nervous system. 1. The Short Corona Radiata Tracts. a. One portion of the corona radiata tracts passes from all the convolutions of the cortex into the optic thalamus, coming from out the internal capsule as anterior, posterior, and inferior stalks of the thala- mus, and disappears in the thalamus, the corona ra- diata of the thalamus. A part covers the surface of the thalamus before their entrance, stratum zonale. b. Another portion passes in a similar way into the nucleus caudatus and there disappears. This portion is to be considered as association tracts. c. A portion arising from the occipital lobes, the cuneus, collects in the hindermost portion of the posterior limb of the internal capsule and passes to the primary optic centres, to the pulvinar of the thalamus, to the lateral geniculate body, and to the anterior quadrigeminal body. This portion is known as the optic radiation of Gratiolet. From here the optic tract passes farther. 2. The Long Corona Radiata Tracts. These come from all parts of the cortex, descend in the internal capsule, and pass under the thalamus in the subthalamic region into the tegmentum of the cerebral peduncles, and in part into the crusta. a. Tegmental Tracts. A part of these pass directly out of the posterior limb of the internal capsule; another part, after pene- trating the inner segment of the lenticular nucleus (ansa lenticularis from the globus pallidus) and DEVELOPMENT AND STRUCTURE. 33 breaking through the portion of the internal capsule which lies mesially therefrom in the tegmentum, runs thence as fillet tract farther downward through the medulla as far as its inferior termination, consti- tuting the mesal and lateral fillet tract, central sen- sory tract. b. Crusta Tracts. All of the corona radiata fibres that have not yet branched off pass out of the anterior and posterior limbs of the internal capsule in the crusta and thus out of the hemispheres. The fibre bundles here are considered of three different origins. 1. The Mesal Bundle of the Peduncle. — This arises possibly from the cortex of the frontal lobes, passes through the anterior limb of the internal cap- sule, and ends in the pons ganglia, frontal pontine tract. 2. The Lateral Bundle of the Peduncle. — This comes positively from the temporal and occipital lobes, passes through the posterior limb of the inter- nal capsule, and ends likewise in the pons ganglia, the temporo-occipital pontine tract. 3. The Middle Bundle of the Peduncle. The Pyramidal Tracts. These arise from the cortical cells of the central convolutions and their vicinity (posterior parts of the first and second frontal gyri), are collected together in the internal capsule, pass in the knee and anterior third of its posterior limb and then through the crusta, where it lies between the mesal and lateral bundles just described. 3 34 ATLAS OF THE NEKYOUS SYSTEM. This segment is also the only continuation of the crnsta fibres which pass through the pons on its pos- terior border as pyramids and which course farther downward through the spinal cord as the pyramidal tracts. This tract passes in the lateral columns after the larger part of the fibres has crossed over to the opposite side ; the uncrossed, smaller portion remains in the anterior columns. This tract is the longest of all the corona radiata fibres, it being possible to fol- Fio. 4. low the longest fibres in the lateral columns (crossed) as far as the conus medullaris. From the cerebral peduncles on, this tract continues to give off fibres which pass to the motor nuclei of the opposite side. It constitutes the central motorial tract. The position of this tract is well illustrated by the accompanying schematic representation of the cap- sule, which is modified from Edinger (Fig. 4) . The DEVELOPMENT AND STRUCTURE. 35 direction and position of the tracts are as have been described. To these corona radiata fibres which arise from the cerebral cortex come yet others that originate in the basal ganglion and optic thalamus, coursing down- ward as short tracts. To these belong : 1. Those fibres which pass from the nucleus cau- datus and putamen to the optic thalamus, to the inner member of the lenticular nucleus, and farther down- ward to the substantia nigra of the cerebral pe- duncles. 2. Those tracts which arise from the optic thala- mus and pass to the tegmentum and there terminate (red nucleus, substantia reticularis). In the tegmentum of the cerebral peduncles there begin new fibre tracts. One of these, which passes close beneath the gray matter of the aqueduct, the posterior longitudinal bundle (fasciculus longitudi- nalis posterior) , connecting individual cranial nerves, can be traced into the cervical cord. A larger one likewise passes out from the red nucleus, crosses with its fellow of the opposite side, and goes to make up the brachium conjunctivum (processus cerebelli ad corpus quadrigeminum), passing to the hemispheres of the cerebellum and ending in the corpus dentatum and cerebellar hemispheres. From the cerebellum fibre tracts pass in or out. Such are the processus cerebelli ad pontem, which crosses to and ends in the pons of the other side, and the processus cerebelli ad medullam oblongatam, the restiform bodies; they consist of fibre tracts from the cerebellum to the olivary bodies and to the pos- terior and lateral columns of the spinal cord (late- 36 ATLAS OF THE NERVOUS SYSTEM. ral cerebellar tract), partly long and partly short tracts. In addition to these the cerebellum, like the cere- brum, contains commissural and association tracts. The constitution of the spinal cord, as it is made up of the projection fibres of the cerebrum and cerebel- lum and of the pyramids and restiform bodies, is easily understood from what has been said on page 16. On cross section of the spinal cord we recog- nize both halves separated anteriorly by the anterior longitudinal fissure. In the median line is the white commissure, passing transversely from one anterior horn to the other; just behind this is the small cen- tral canal, posterior to which is the posterior com- missure. The gray substance in the anterior and posterior horns is surrounded by the anterior, lateral, and pos- terior columns. 1. The anterior column consists of the uncrossed fibres of the pyramidal tract and the anterior ground bundle which is the continuation of a portion of the substantia reticularis of the tegmentum. 2. The lateral column: the crossed pyramidal tracts comprise the lateral cerebellar tracts from the restiform bodies, Gowers' bundle, the anterior lat- eral bundle, and the lateral limiting layer which comes in part from the tegmentum. 3. The posterior column consists of the column of Goll and the column of Burdach and the root zones. A more detailed specification of the course and sig- nificance of the tracts that have been spoken of, as well as of others not mentioned, follows in Section III. What has been said will be more readily under- DEVELOPMENT AND STRUCTURE. 37 stood if studied in connection with the serial sections in Plates 24 to 47. The finer relations of the gray substance of the cortex, the basal ganglia, the thala- mus, and the nerve nuclei cannot be understood from illustrations alone; plates and text must be studied in conjunction. In the study of the serial sections it should be re- membered, in order to facilitate rapid orientation, that the cerebral cortex is red and the basal ganglia and nuclear deposits are blue. SECTION" III. Anatomy and Physiology of the More Im- portant Nerve Tracts. (Plates 49 to 52.) By the word tract it is proposed to designate the anatomical substratum in its entire connection, that serves to conduct a physiological excitation from a ganglion cell as far as the excited end organ. Every individual physiological functionating tract consists of many neuron complexes in connection. Each individual neuron complex has, however, its own anatomical and physiological individuality. There exist tracts which are made up of two, sometimes three, perhaps more neuron complexes " coupled" one after the other. The more important of these, the tracts belonging to the projection system of the cerebrum and cere- bellum, are the following : A. TRACTS WITH KNOWN FUNCTION. 1. The motorial, cortico-muscular, centrifugal con- ducting pathway, consisting of two neuron com- plexes. 2. The sensory, centripetal conducting pathway, consisting of at least two, probably three or more neuron complexes. 88 ANATOMY AND PHYSIOLOGY. 39 Both tracts come into connection in two parts of their course. (a) There exists an inferior connection : the reflex pathway, independent of the influence of the will, in the subcortical nuclear layer. (b) A superior connection (in the cortex) ; the tract of conscious will reaction. The course of the motorial pathway is much sim- pler and much better known than that of the sensory. We now consider these tracts and their connections in the above-named order : 1. The Motorial Tract. • The tract in its entirety is made up of two or more neighboring neuron complexes, the central and the peripheral motor neuron. The cells of the central neuron, situated in the cor- tex of the central convolutions, i.e., the pyramidal cells of the cortex, send out their nerve fibres, to the pyramidal tract, in the well-known way through the corona radiata, through the knee and anterior third of the posterior limb of the internal capsule into the crusta. Passing through the pons, they continue as the pyramids. In the pyramidal crossing, the greater part of the fibres pass into the lateral columns and continue as the tract of the crossed pyramidal lateral column. In the cervical cord this tract lies at the depth of the lateral columns. But it approaches more and more to the periphery in its descent to the conus medul- laris, where it terminates. A small portion of this tract passes, without crossing, in the anterior col- 40 ATLAS OF THE NERVOUS SYSTEM. umns and is known as the anterior pyramidal tract. It can be traced only as far as the upper lumbar cord. Throughout the length of this extended pathway there pass off at all levels between the crusta and the inferior termination definite fibre tracts which cross over to the opposite side (see Fig. 5, which shows the pyramidal tract viewed from below). These fibres ramify and end in the mo- tor nuclei region of the brain stem and spinal cord. The total mass of the py- ramidal tract, in conse- quence of this, diminishes continually as it passes downward. In addition collaterals pass from the continuous fibres to nuclei lying higher up. The total central neuron mass, therefore, is finally split up within the sub- FlG - 5 - stations which lie, as has been mentioned, at various levels (segments) of the brain axis and spinal cord. This ramification of the fibres surrounds the cell processes of the ganglion cells of the peripheral motor neuron which begin from this point. The nervous process of these cells passes out from the brain axis and anterior horn of the same side as the anterior nerve root and runs as a fibre of the motor nerves to the muscle, in the single muscle fibrils of which the terminal ramification of the fibre takes place (motor end plate). ANATOMY AND PHYSIOLOGY. 41 The central motor neuron runs therefore crossed, the peripheral uncrossed. See Fig. 7 of the text. In the tract which is thus made up of these two neu- rons, the motor impulses that originate in the cells of the cerebral cortex pass to the muscles. In conse- quence of the decussation of the central neuron, they pass from the cortex of each hemisphere to the mus- culature of the other side of the body. Every neuron cell exercises a preservative influence upon its processes, including the long axis-cylinder process. The cessation of this influence results in atrophy of the involved nerve fibre, and even the ganglion cell itself suffers alteration after profound changes within the neuron continuity. The cells of the peripheral neuron exercise in addition a similar influence upon the muscle fibre which it supplies. In detail, the most important members of the motor tract are the following, stated in order from above downward. 1. Oculo- Motor Nerve. — Its central neuron com- plex arises at some unknown location in the cerebral cortex (gyrus angularis?). It runs through the knee of the internal capsule, separates, however, from the pyramidal tract, in the cerebral peduncles probably as a constituent of Spitzka's bundle (see Plate 35, 2, s). The latter arises from the most mesially lying portion of the pyramidal region in the peduncle, turns mesal and upward, and terminates after trespassing beyond the middle line in the nucleus of the motor oculi of the opposite (and of the same?) side, which lies in the central ventricular gray matter beneath the aqueduct of Sylvius. Around the ganglion cells of this locality is found 42 ATLAS OF THE NERVOUS SYSTEM. the terminal ramification of the central neuron of the motor oculi. With these cells and their arborization begins the peripheral neuron. The nerve fibres pass out of the nucleus as the roots of the motor oculi on the same side, in lesser part also decussating with fibres of the other side, and run in the motor oculi trunk to the muscles of the eye. (For further de- tails concerning subdivision and function see explan- ation of Plate 23.) The position of the motor oculi nucleus, etc., is shown in Plates 18 and 19 and also in Fig. 6 of the text, p. 48. Herein is also to be seen the supposed order of the portions of the nucleus corresponding to the separate eye muscles. 2. Trochlear Nerve. — Central neuron runs as in the preceding. After decussation, the terminal ramification of the fibres is found in the crossed trochlear nucleus, below the posterior corpora quad- rigemina behind the motor oculi nucleus. The pe- ripheral neuron begins there and passes out as the trochlear nerve behind the corpora quadrigemina, decussating completely with the nerve of the oppo- site side. 3. Motor Branch of the Trigeminus. — Its central neuron originates in an unknown locality of the cerebral cortex (inferior parietal gyrus?), passes through the knee of the capsule behind the nerve fibres of the eye muscles, separates from the crusta in the bundle of Spitzka (?), decussates in the raphe of the tegmentum, and terminates, surrounding the cells of the motor nucleus of the fifth, which is situ- ated laterally in the pontal part of the tegmentum. From here the motor root of the fifth continues its course farther as peripheral neuron. It passes as ANATOMY AND PHYSIOLOGY. 43 anterior root out of the pons and receives also fibres from the motor nucleus of the other side. Even the nasal root of the fifth (descending root) is said to convey motor (trophic?) fibres. This root arises from the lateral portion of the central ventricular gray substance of the aqueduct and of lower parts from large cells situated there until it unites with the anterior root of the fifth as it passes outward. 4. Abducens Nerve. — Its central neuron runs as related in 1. Beyond the decussation the terminal endings of the fibre take place in the nucleus of the abducens beneath the floor of the fourth ventricle, near the middle line. The peripheral neuron passes out from its cells as the abducens nerve and runs through the posterior part of the pons. 5. Facial Nerve. — Its central neuron complex arises from the cells of the lower third of the central convolutions. The tract passes in the posterior limb of the internal capsule, behind the knee, separates from the pyramidal tract in the bundle of Spitzka (?), decussates in the raphe of the tegmentum, and enters the facial nucleus of the other side which lies later- ally, long drawn out in the tegmentum situated deep in the medulla. From here pass upward and inward the single facial fibres as peripheral neuron, and col- lecting together at the genu facialis they finally bend outward in a great bow and then downward, when they for the first time pass out of the medulla as the facial nerve. This is the lower, mouth-cheek facial. The central neuron for the upper facial, temporo- facial, appears to pass otherwise in some unknown manner. Its peripheral neuron is said to pass out of 44 ATLAS OF THE NERVOUS SYSTEM. the hindmost portion of the oculomotor nuclei and to reach the trunk of the facial. For the orbicularis oris branch the involvement of fibres from the nucleus of the hypoglossus is as- sumed (?). 6. Motor Portion of Glosso-Pharyngeal — Vagus. The central neuron arises from unknown portions of the cortex (middle frontal convolution [?]), passes with the pyramidal tract downward and reaches, after decussating, in some unknown manner the nucleus ambiguus, which it may be assumed is the motor nucleus for this neuron, situated deeply in the poste- rior portion of the medulla. From this point on the fibres of the peripheral neuron accompany in great part the vagus. 7. Hypoglossal Nerve. — The central neuron arises from the lower third of the central convolutions in front of the facial centre, runs downward in the in- ternal capsule behind the tract of the facial, separates in Spitzka's bundle (?) from the pyramidal tract, de- cussates in the raphe of the tegmentum, and reaches the nucleus of the hypoglossal of the other side, about whose cell it branches. From here the periph- eral neuron passes out through the medulla as the hypoglossal nerve. The tracts described under 5, 6, and 7, particu- larly those that arise from the left hemisphere, are specially used for the act of speaking. These cen- tral neurons, therefore, together comprise the central speech tract; the peripheral, the peripheral speech tract. A particular speech tract has also been as- sumed, but not demonstrated. 8. Spinal Accessory. — The central neuron is said ANATOMY AND PHYSIOLOGY. 45 to come from the basal median frontal convolution, running along with the pyramidal tract ; it reaches in an unknown manner the nucleus of the accesso- rius of the opposite side in the lower portion of the medulla and in the uppermost cervical cord. From here the peripheral neuron passes out as the spinal ac- cessory nerve. An important portion of the nerve, the inner branch, continues farther with the vagus nerve. 9. The Motorial Tracts of the Upper Extremity. — Their central neuron complex arises from the cells of the middle third of the central convolutions, espe- cially of the anterior convolution, passes downward through the posterior limb of the internal capsule (an- terior third), and continues along with the pyramidal tract through the crusta and pons into the pyramids. In the decussation of the pyramids the greater part passes into the lateral column of the other side. The smaller part (here are found individual variations) passes downward uncrossed in the anterior columns. At the level of the cervical cord the fibres bend in succession at right angles and run out of the lateral pyramidal tracts into the anterior horn of the same side ; from the anterior pyramidal tracts through the anterior commissure into the anterior horn of the other side.* Here they ramify about the cells of the anterior horns, especially about the lateral groups and their dendrites. With these cells the peripheral neuron of these tracts begins. The nerve fibres of these cells pass * This last crossing of the anterior pyramidal tract has been questioned recently, and very properly ; in consequence the termination of this tract in the anterior horn of the same side must be regarded as hypothetical. 46 ATLAS OF THE NEKYOUS SYSTEM. out as anterior roots and (fourth cervical to first dor- sal root) extend to the brachial plexus, from which they pass out, forming the different nerves of the arm (see Plate 23 for explanation). For the position of the cells of the anterior horns and their relation to the single muscles the text figure on page 48 gives the clearest representation. Above these tracts those for the anterior and pos- terior neck muscles pass, and under the latter those for the chest and trunk muscles. Their topography can be readily seen by reference to the plate just mentioned. The central course of these tracts is very little known. The centre for the movement of the trunk is in the upper frontal convolutions. For these tracts the descent is not only from the crossed but in all probability likewise from the hemisphere of the same side. Many other muscles, especially those which functionate bilaterally (eye and fore- head muscles), receive in all probability innervation from the hemisphere of the same side, and, as has already been described, from the crossed hemisphere. Nevertheless these crossed (or double crossed) central pathways are not in man further known (uncrossed anterior pyramidal tract). 10. The Motorial Tracts for the Loiver Extrem- ity. — Their central neuron arises in the upper third of the central convolutions and the lobus paracen- tral, passes in the pyramidal tract through the pos- terior limb of the internal capsule (in the middle of the limb), then farther down, as described in 9, under- goes partial decussation, and the greater portion reaches the lumbar region by way of the lateral py- ramidal tracts. Here its fibres turn and pass to the ANATOMY AND PHYSIOLOGY. 47 anterior horn, where they have their terminal rami- fication. From the anterior horn cells, especially from the lateral cell groups, the anterior roots (1-5 lumbar and 1-5 sacral) pass as the peripheral neuron. The latter pass into the lumbar and sacral plexus and subsequently constitute the nerves of the lower ex- tremity; see Plate 23 and text figure 6, in which the relationship of the muscle to the segments of the brain axis and spinal cord is given on the right side. 11. Tlie Motor Tracts for the Bladder, Rec- tum, and Sexual Organs arise from unknown re- gions in the brain. Their central neuron does not pass downward in the lateral pyramidal tracts, but in all probability in the anterior lateral ground bun- dle. It ends in the gray . substance of the sacral cord. From here the peripheral neuron passes out through the second to fourth sacral roots to the pudendal plexus, etc., and eventually to the muscles of the above-mentioned organs (see Plate 23). 12. To the sympathetic system pass central motor fibres, of unknown cortical origin, through the lat- eral tracts and which appear to terminate in the an- terior horns (lateral horns). Here begins the periph- eral neuron which goes out through the anterior root, ending in the ganglia of the sympathetic chain and in their analogues. In the cells found here begins the motor sympathetic neuron whose fibres pass to the various unstriped muscles, blood-vessels, intes- tines, heart (?), glands, etc. 2. The Sensory Pathway. As sensory impressions are carried from the pe- riphery to the centre we shall follow that direction LOCATION OF THE SEGMENT FOR Should w (Musculu-splral nerv ,E. Median nerv g, [Ulnar nerve Gluteal region Inguinal region external posterior Internal Anterior Foot Scrotum, IYnls, etc. Rectum, Bladder Motility. Muscles ^sphincter of the iris ciliary -Internal rectus, levator palpebral superioris rectus, interior and superior *rior oblique .Superior oblique , Masseter, temporal, pterygoids [(upper facial) External rectus, frontalis, orbicularis of eye Mimetic face muscles (lower facial) Mouth and throat muscles Laryngeal muscles Tongue muscles Sterno-cleido mastoid Deep neck muscles Trapezius, Serratus anticus Diaphragm Deltoid, biceps, pectoralia (clavicular part) Brachialis anticus, supinator longus Triceps, latissimus dorsi, pectoralis (costal por- Extensors of the lingers and phalanges ) tion) Fore- Flexors of the fingers i Interossei and lumbrie Thenar, hypothenar Intercostal muscles Baclt muscles Abdominal muscles d phalang {Hand r}> Sartorius Adductors Abductors Quadriceps Thigh Leg . Pcronel Kiexors, extensors of foot and toes "luteal .Perineal ) •■ Bladder -Musculature "• Rectum ) Fig. C— Explanation of the Abbreviations.— f>. o//=olfactory tract, c. ;/./.= lateral Keniculate body ; p.,r.,cr„ pat, A., represent approxi mately the location of the reflex centres; the pupillary reflex (p.), for the respiratory reflex (r.), for the cremaster reflex (cr.j, patellar reflex , '/><''•), and the Achilles reflex (A.X The centres for the bladder anil rectum in the sacral cord are represented by circles; likewise the centres for erection atul ejaculation. The centre for contraction of the uterus is probably likewise in this vicinity. ANATOMY AND PHYSIOLOGY. 49 in our consideration of them, starting with the pe- ripheral neuron. The peripheral sensory neuron complex of the extremities and the trunk passes in the sensor}' fibres of the peripheral nerves (their exact distribution in the skin is shown in text figures 10-12, see also Fig. G, left side) spinalward through the plexus fibres, and terminates before its entrance into the spinal cord in the cells of the spinal ganglia. From each cell there passes a fibre in the opposite direction. These fibres gather to the posterior roots. The sensorj 7 peripheral neuron passes into the spinal cord first by way of the posterior root fibres. They enter in two portions at the border of the posterior horn and posterior column. The two portions are: 1. The small, lateral portion of the posterior root. It enters at the apex of the posterior horn into Lis- sauer's area. Here its fibres divide into an ascend- ing and a descending branch. Both are short tracts. They pass with a sharp turn into the posterior horn and split up around cells which are there situated. 2. The medial, which is the most developed por- tion of the posterior root fibres, passes into the lat- eral portion of the posterior columns (Burdach's col- umn, likewise known as the posterior root zone). Here its fibres fork into ascending and descending branches. The descending branches are short tracts; they soon turn at right angles into the posterior horn and branching, there terminate. The ascending divi- sions are in part short, in part long tracts. The short tracts soon turn and a part of them pass into the posterior horn, while the remainder have their termination in the cells of Clarke's column and 4 50 ATLAS OF THE NERVOUS SYSTEM. the anterior horns. The long tracts pass at first up- ward in Burdach's columns. Soon after their en- trance, however, they approach very much nearer the middle line, principally on account of the recently entering ascending long root fibres. The long fibres that pass into the lumbar cord continue in the cervi- cal cord in GolPs column, to the outer side of which pass the posterior root fibres which enter at a higher level (in the dorsal and cervical cord). These long, ascending tracts have their terminal ramifications around the cells of the posterior col- umns of the medulla, the nucleus funiculus Goll, and nucleus funiculus Burdach). All of these variously coursing fibres constitute to- gether the peripheral sensory neuron complex. The cells of this neuron consequently lie outside of the spinal cord in the intervertebral ganglion. The cell ramification (dendrites) is the very much elongated peripheral nerve, considerably extended in the longi- tudinal direction, together with its cutaneous ter- minal branchings. The nervous process is the pos- terior root fibre with its fibre ramifications that terminate in different parts and levels in the spinal cord. The fibres split up or ramify about cells that lie: 1. In nuclei of the posterior columns of the me- dulla (Goll's and Burdach's nucleus). 2. In the posterior horns in their various portions. 3. In the so-called middle zone (between the ante- rior and posterior horns). 4. In Clarke's columns. 5. In the anterior horns. From 1-4 inclusive, the central sensory neuron ANATOMY AND PHYSIOLOGY. 51 complex takes its origin. The ramifications that end under 5 may be regarded as reflex tracts. So far all the facts are comparatively certain. Although the further course of the central sensory tract is better understood than formerly, it is still very obscure. The mooted points will be briefly considered later on. The course of the sensory tracts given here will be that which harmonizes best with the postulates of pathology. Anatomically, the course of the sensory tract in man is not yet completely established. The central sensory neuron begins, in keeping with the terminal ramifications of the peripheral, partly in the already mentioned portions of the medulla, partly in the anterior and posterior horns of the spinal cord. The individual parts will be consid- ered in the order (1-4) cited above. 1. From the cells of the posterior column nuclei, the nucleus of Goll and of Burdach, in the medulla begins the central neuron ; the fibres pass as the in- ternal arcuate fibres in form of a bow downward and turn toward the raphe. Here they pass over the me- dian line (fillet decussation the beginning of which is to be seen in Plate 41, 1. It terminates at the level of Plate 39, 2). After this decussation the fibres uniting reach, dorsally, over the pyramids that have already decussated deeper down, to the neighborhood of the anterior ground tracts, where they are known as the layer of the fillet (principal fillet, laqueus supe- rior). The fillet increases in area in its further cen- tral course and forms, between the olives, the inter- olivary layer lying close upon the median line. Farther up the fillet continues its course in the tegmental region and lies, widely expanded, trans- 52 ATLAS OF THE NERVOUS SYSTEM. versely beneath the same ; here it is also known as the median fillet. Thus it continues throughout the pontal tegmentum. In the tegmentum of the crura it swerves completely from the median line and lies lateral to the red nucleus. From this region the superior fillet reaches the subthalamic region, about the level at which the red nucleus terminates. The fillet passes partlj 7 through the internal capsule (fibres of the peduncle), running transversely as a part of the ansa lenticularis, breaking through the inner portions of the lenticular nucleus, and rising in the posterior limb of the capsule to the cortex of the pos- terior central convolutions and parietal lobe. The terminal ramification of the fibres of the neuron takes place about the bodies of cells that lie in these cortical regions. This part apparently is in some manner interrupted in the globus pallidus. Another portion of the superior fillet emerges ap- parently from out of the subthalamic region, and passes directly into the internal capsule, in which it ascends behind the pyramidal tracts, terminating in the above-mentioned cortical areas. A portion or all (?) of these fillet fibres seems to be interrupted in the ganglia of the subthalamic region, the globus pallidus, and the optic thalamus (lateral basal nuclear portion). For cortical conduction it is necessary, therefore, to conceive of a third, centro- cortical neuron (in the optic radiations of the thala- mus?). Concerning this, we have no satisfactory knowledge. This is also called the superior or cortico-thalamus fillet. 2. The central neurons beginning in the cells of ANATOMY AND PHYSIOLOGY. 53 the posterior horns constitute short tracts that termi- nate for the most part within the spinal cord. Their fibres pass into the border zone of the lateral tracts of the same side (funiculus lateralis of the serial sec- tions, Plate 39, and the following) and also into the posterior tract (ventral field of the same). After a short course upward, in part also downward, they terminate, bending again into the gray substance and splitting up. Similar tracts then connect with these ; the conduction, therefore, takes place in the manner of relays in that one short tract connects with another. In the medulla these fibres enter into the reticu- lated substance of the tegmentum and terminate in its nuclei . From the cells of the reticulated substance (nucleus magnocellularis in its entirety) it is supposed that fibres pass to the cortex, annexing themselves to the fillet. 3. From the cells of the middle zone originate three varieties of fibres, partly long, partly short tracts. a. Fibres that enter into the anterior lateral tract of the same side passing upward in it. One portion is short and terminates bending inward into the gray substance. Another portion passes farther up, reaches the substantia reticularis tegmenti (lying adjacent to the fillet?) fal of the sections. b. Fibres that enter Gowers' tract of the same side and pass up to the medulla as long tracts. All long tracts send throughout their course at different levels collaterals to the gray substance. Gowers' tract passes likewise into the substantia reticularis tegmenti of the medulla. Its termination in the brain stem (thalamus?) is still doubtful. 54 ATLAS OF THE NERVOUS SYSTEM. c. Fibres that arise from the median group of cells, especially of the anterior horn, pass (cells of the commissure) to the median Hue, decussate in the anterior commissure, and pass through the anterior horn of the other side into the anterior lateral tract of this side and pursue their course as long (?) tracts with those mentioned under a. In the medulla they probably join the fillet, no doubt interrupted in the cells of the substantia reticularis of the tegmentum, and run upward with the same toward the cortex. 4. From the cells of Clarke's columns fibres of the central tract pass into the lateral cerebellar tract of the same side (Cb in the sections), run upward in the medulla with the restiform body in its most ventral portion and reach with it the medullary sub- tance of the cerebellar hemisphere, terminating in the vermis (in the crossed nucleus tegmenti?) of the same. This is therefore in brief the course of the sensory central neurons for the trunk and extremities. We see that a part of the same runs through the fillet direct to the cerebral cortex, crossing in the decus- sation of the fillet. Another part reaches the cere- bellum direct through the lateral cerebellar tract. On the other hand, a third part the anterior lateral tract reaches only to the substantia reticularis teg- menti of the medulla (in part crossed in the anterior commissure) ; from here on, we must assume a cen- tral cortical neuron to the cortex, beginning in the nuclei of the substantia reticularis [?]. These fibres are said to join in part the upper fillet (border of the anterior tract). In the fillet consequently run the chief masses of the central sensory neurons, to ANATOMY AND PHYSIOLOGY. 55 \.£ -r-v ■• H \S ■ I X ■ ■ ■ H M