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Architecture of the Brain 
 
 WH. FULLER, M. D. 
 
 Formerly Demonstrator of Anatomy, McGill College; Professor of 
 
 Anatomy, Bishop's College, Montreal, Canada; Member 
 
 of the American Medical Association, etc. 
 
 ILLUSTRATED. 
 
 GRAND RAPIDS, MICH. 
 
 J 896. 
 
\ M 455- 
 
 Cofyright, rSgb. 
 
 WM. FULLER, M. D. 
 
 AIL rights reserved. 
 
 Press of 
 
 Seymour Ss' Midr Prhiting Co., 
 
 Grand Rapids, Mich. 
 
 Engravings by 
 Grand Rapds Engraving Co. 
 
NTRODUCTION. 
 
 In the following desci'iption of the Central Nervous 
 System it is not intended to rehearse minute details which 
 can be found in the many excellent works upon anatomy, 
 but to place in view in as clear and concise a manner as pos- 
 sible the general architecture of the central nervous system, 
 and to trace the relation and continuity of its pai'ts. When 
 a general knowledge of the structure of the brain is acquired 
 by the student a useful and practical step is gained, because 
 he will not oiily be able to describe the situation of a lesion 
 and understand the descriptions made by others, but he will 
 be in a situation to intelligently discuss the functions of its 
 parts, and is prepared to work in the field of discov- 
 ery. The incidental assignment of function to any j)art of 
 the nervous system in these pages is intended to assist the 
 memory and awaken enquiry. Nothing stimulates the obser- 
 vation to the same extent as the entertainment of a theory, 
 to be demonstrated or corrected by careful observation of 
 facts which fall under one's own notice, or by those which can 
 be obtained from other reliable sources. 
 
 The following description has been made from dissections 
 by the author, and has been carefully verified by a comparison 
 of longitudinal and lateral dissections, and by sections, all of 
 which agree in proving the correctness of the representations 
 herein described. 
 
 These dissections have been permanently recorded by 
 castings in plaster, and the sections have been photographed 
 
4 ARCHITECTURE OF THE BRAIN. 
 
 and plates made, so that both the casts and the plates can be 
 repeated at pleasure, thus enabling any who may take an 
 interest in the anatomy of the brain to acquire a knowledge 
 of it with ease. 
 
 A cast is much superior to a picture, since it represents 
 correctly the size, relation and direction of the parts in a 
 much plainer manner than can be done by a plate. 
 
 The plates introduced for illustration are drawn from the 
 casts of dissections and refer to them. 
 
 In order to bring the means of acquiring a knowledge of 
 this important department of medical science within the reach 
 of all, an Anatomical Company has been formed to reproduce 
 the casts and plates at a very moderate pi'ice. 
 
THE MEMBRANES OF THE BRAIN. 
 
 The Central Nervous System, or the Cerebro-Spinal axis, 
 is contained in the cavity of the cranium and spinal canal. 
 This cavity is lined by a tough fibrous membrane, the dura 
 mater, which is closely adherent to the inner surfaces of the 
 bones of the skull, especially at the sutures, base, and 
 the mai'gin of the foramen magnum, but is loosely at- 
 tached by fibrous tissue to the bones forming the spinal 
 canal. Its internal surface is smooth, covered by a serous 
 surface which is the outer wall of the arachnoid cavity, and 
 it is perforated by numerous openings corresponding to the 
 foramina of its bony enclosure. These openings are for the 
 transmission of nerves and blood vessels, and the membrane 
 is prolonged outwards, to be continuous with their sheaths and 
 with the periosteum of the skull. As an instance, the dura 
 mater forms a sheath for the optic nerve, expands to form 
 sclerotic coat of the eyeball and lines the walls of the orbit. 
 The dura mater contains between its layers the meningeal 
 arteries and channels for the conveyance of venous blood, 
 called sinuses. The falx cerebri and the tentorum cerebelli 
 are projections of the dura mater extending into the fissures 
 of the brain, respectively between tlie hemispheres of the 
 cerebrum and between the occipital lobes and the cerebellum. 
 The use of these processes are to sustain the parts of the 
 brain in their proper pjosition. 
 
 The arachnoid is a thin fibrous m^^mbiane which surrounds 
 the brain, spmal cord and the roots of the nerves. It covers 
 
b AECHITECTURE OF THE BRAIN. 
 
 the convolutions of the brain, but does not dip into the sulci 
 between them. It is somewhat loosely attached to the sur- 
 face of the brain, but closely adherent to the pons, medulla 
 and spinal cord, as well as to the roots of the nerves which 
 it encloses and supports between their origin and the fora- 
 mina of the dura mater before mentioned. The intervals 
 between the arachnoid membrane and the pia mater beneath 
 are called the sub-arachnoid spaces. These communicate 
 with each other and with the ventricles of the brain and in 
 certain pathological conditions are the seat of effusion. The 
 arachnoid is continuous with the inner serous surface of the 
 dura mater enclosing the arachnoid cavity. Upon each side 
 of the spinal cord, between the roots of the nerves and 
 throughout its whole length, this membrane sends out deli- 
 cate projections which are attached to the inner surface of the 
 dura mater, the function of which is to preserve the position 
 of the spinal cord in the spinal canal. Together they are 
 called the ligamentum dentatum. 
 
 The pia mater immediately invests the nervous sub- 
 stance of the brain and spinal cord, is the vascular membrane, 
 and is made up of an intricate network of blood vessels of 
 various sizes, which break up into numerous minute vessels that 
 penetrate the nervous mass and are distributed to it. In a sec- 
 tion of the brain these vessels are divided and are seen as 
 points or specks on the surface of the section, and are called 
 puncta vasculosa. Those blood vessels which are distributed 
 to the grey masses, or nerve centres within the brain, are large 
 and numerous, while those in the white matter are smaller 
 and fewer in number. Projections of the pia mater extend 
 through fissures into the ventricles, or cavities within the 
 brain, with which they will be described. Attached to these 
 projections of the pia in the ventricles are several close capillary 
 
THE MEMBRANES. 7 
 
 networks, one for each ventricle, which are called the choroid 
 plexuses and which will also be described with the ventricles of 
 the brain. The network of blood vessels constituting the pia 
 mater is held together and supported by fine filaments of 
 fibrous tissue attached on the outer side to the inner surface of 
 the arachnoid membrane, and on the inner extending into the 
 substance of the brain with the framework of which it is con- 
 tinuous. The arachnoid membrane before described is a 
 condensation of the fibrous tissue of the pia mater over the 
 surface of the brain covered externally by a serous sur- 
 face, in the same manner as the internal surface of the dura 
 mater is covered internally by a membrane of the same 
 serous character. These serous surfaces are continuous, 
 therefore it may be said, that in reality there are but two 
 membranes of the brain, viz. , the dura mater and the pia 
 mater, each having a serous surface which together enclose a 
 serous cavity. 
 
 To sum uj) : The brain is supplied with a dura mater for 
 protection, the arachnoid to accommodate its movements and 
 the pia mater to provide for its nourishment. 
 
THE CEREBRO SPINAL AXIS. 
 
 The mass of nervous matter included under this heading 
 is commonly referred to as the brain and spinal cord. The 
 brain is that portion of it which is contained within the 
 cranial cavity, and the spinal cord is the part suspended 
 within the spinal canal. In this description we will view the 
 axis as an isolated object, and the divisions of it made for 
 the convenience of description, will be marked by distinctions 
 upon the axis itself, without any reference to the relations of 
 its parts to those of any other part of the body. 
 
 After giving a genei'al description of the structure of any 
 part, we will direct the attention to the natural order of dis- 
 section from above downwards, as represented by the castings 
 before referred to, which are intended to accompany and 
 illustrate these pages. 
 
 When the anatomy of the spinal cord has been reached in 
 the order of description and studied, its various columns will 
 be traced upwards to their associations above, by which a 
 complete review of the whole will be brought before the 
 mind and its parts associated into the formation of a structure. 
 
 A very proper and convenient di vision of the cerebro spinal 
 axis is the ce7^ebrum, cerebellum and spinal cord with their 
 respective conections, and in this description we will follow 
 the divisions commonly in use though without strict adherence 
 to old boundaries. We will, for instance, say that the cere- 
 brum is all that portion of the brain above the pons Varolii, 
 including the hemispheres their peduncles and commissures. 
 
THE CEREBRO SPINAL AXIS. V 
 
 The cerebellum and pous will be described together, on ac- 
 count of the close association of their parts and the necessity 
 of maintaining the analogy between this structure and that 
 of the cerebrum. Tlie medulla oblongata will be outlined, 
 as that portion of the spinal cord which extends from the 
 lower border of the pons Varolii to the lower part of the 
 decussation of the anterior pyramids of the medulla, below 
 which point is the spinal cord proper. 
 
 Viewed as a whole the cerebro spinal axis presents two 
 lateral halves, united by commissures and divided in the mid- 
 dle before and behind by a continuous but modified longi- 
 tudinal fissure, which in front is called the anterior and 
 behind the posterior median fissure. 
 
 The Median Fissure. — The median fissure divides the 
 axis into lateral halves and has diflferent names applied to it 
 in the difi'erent localities in which it lies. In front of the 
 spinal cord it is called the anterior median fissure, which is 
 partially interrupted at about an inch below the pons Varolii 
 by the decussation of the anterior pyramids of the medulla ob- 
 longata. Unless the groove upon the front of the pons Varolii 
 which lodges the basilar artery may be called a continuation of 
 the anterior median fissure, this fissure is' completely inter- 
 rupted to the extent of about one and half an inch by the 
 transverse fibres of the pons. Above the pons, this fissure 
 is broad and expanded between the peduncles of the cere- 
 brum, where it is called the interpeduncular space, in front of 
 which, at its termination in the great longitudinal fissure of '"■ss. 
 the cerebrum, it is interrupted by the optic commissure. 
 
 The sides of the interpeduncular space are connected in 
 front with the commencement of the fissures of Sylvius, and 
 
 Note.— The vertical sections are numbered separately to indicate the situation of each cut 
 upon plates 25 and 26 and are marked by a * thus (26*). The general plates are referred to by simple 
 numbers. 
 
 edian fissure 
 
 Compan 
 
10 AECHITECTUKE OF THE BRAIN. 
 
 behind with the lateral extremities of the great transverse 
 fissure. 
 Great longitudinal The great longitudlnal fissure separates the hemispheres 
 
 2-17-24-26. of the cerebrum from each other, it averages about two and 
 
 one-half inches in depth, and at its bottom is the corpus cal- 
 losum, the great commissure of the cerebrum which unites the 
 hemispheres. Behind the posterior extremity of the corpus cal- 
 losum this fissure joins the great transverse fissure, which it 
 
 Intersection with. , 'inpii ti it * 
 
 transverse fissure lotersects lu the middle or the latter. Beneath the posterior 
 extremity of the corpus callosum both communicate with the 
 cavity of the third ventricle. A process of pia mater, called 
 
 ^'tmn'^Ff'"''"^'' ^^^ velum interpositum, passes through this opening or fissure, 
 the fissure of Bichat, into the third ventricle. A longitudinal 
 
 Groove. Fig. 8. groove Separating the tubcrcles of the corpora quadrigemina, 
 and lower down a depression upon the upper surface of the 
 valve of Vieussens, mark the continuation of the median fis- 
 sure, which is now interrupted by the cerebellum. The fissure is 
 
 incisura. Figs. 27- indicated upon the cerebellum by a notch in front and one 
 behind, the incisuia anterior and posterior of the cerebellum. 
 
 Posterior median Bclow the cerebellum, the posterior median fissure begins at 
 
 fissure. Figs. 8- ' r ^ S 
 
 ■0 the lower extremity of the fourth ventricle, and extends 
 
 throughout the length of the spinal cord. The posterior 
 median fissure of the spinal cord is deeper and narrower than 
 the anterior, and its sides are more difficult to separate. 
 
 The ventricular system. — In the centre of the mass 
 throughout its whole length is a cavity or ventricle which is also 
 modified at different points along its course. In the spinal cord 
 it is a slender canal which, behind the medulla oblongata, con- 
 nects with the posterior median fissure by an interruption of the 
 posterior commissure of the spinal cord. At this point, on 
 account of the lateral separation of the posterior columns of 
 the cord, the minute canal expands into a broad cavity, the 
 
 :entral canal of 
 spinal cord. Figs. 
 8-10. 
 
TUB CEREBRO SPINAL AXIS> 
 
 11 
 
 fourth ventricle, which is situated behind the upper half of 
 the medulla oblongata and the pons Varolii, and is beneath the 
 cerebellum. Above the pons, the cavity of the fourth ventricle 
 is contracted into a canal about the size of a small quill, 
 the iter, which is about five-eighths of an inch in length, lies 
 beneath the optic lobes and between the crura of the cerebrum, 
 and connects the third and fourth ventricles of the brain. 
 
 The iter terminates above in a vertical slit, the third 
 ventricle, situated between the opposed sides of the thalami 
 optici, or basal ganglia of the cerebrum. The third ventricle 
 reaches below to the base of the brain, and above extends lat- 
 erally outward over the thalami to the edges of the fornix, 
 beneath the margins of which it is continuous with the lateral 
 ventricles of the hemispheres. The lateral ventricles are 
 large cavities, one in tha center of each hemisphere, pro- 
 longations of which extend into the lobes of the hemispheres, 
 and are called the anterior, middle and posterior corima of 
 the lateral ventricles. 
 
 Thus it may be said that the cerebro spinal axis is a hoi 
 low tube of nervous matter divided into lateral halves which 
 are separated by a fissure and united by a commissure. The 
 cavities Avill be again described in connection with the parts 
 that enclose them. 
 
 Fourth ventrici 
 compose fifiuri 
 8-10-13 15 26. 
 
THE CEREBRUM. 
 
 Superior surface. 
 Figs. 1-24 26. 
 
 Inferiors 
 Figs. 2-' 
 
 Frontal surface 
 
 Olfactory i 
 bulbs and fissure. 
 Figs. 2-7. 
 
 Temporal lobes. 
 
 THE SURFACE. 
 
 Separated from the rest of the mass of the Central Ner- 
 vous System and viewed, the cerebrum is much the largest 
 part, being about eight times the weight of the cerebellum, 
 and thirty times that of the spinal cord. It averages seven 
 inches in a longitudinal and five inches in a transverse diame- 
 ter. It is convex upon its upper surface, and its sides 
 seen from above, present an oval contour. 
 
 Turned over, its under surface in a general aspect is oval 
 and flat. This surface presents three lobes and two surfaces, 
 and is divided into lateral halves by a continuation of fissures 
 and depressions. 
 
 The anterior or frontal portion is a flattened surface divided 
 in the middle by the anterior median fissure. The marginal 
 convolutions, which form the sides of the fissure, are elevated 
 above the rest of the surface, and the parts upon each side 
 of the elevation are triangular and slightly concave, corres- 
 ponding to the upper surfaces of the orbital plates of the 
 frontal bone, upon which they rest in their normal, position 
 in the cranial cavity. On the sides of the median fissure, and 
 removed half an inch from it, are two other fissures, one on 
 either side, which run parallel to it and lodge the olfactory 
 bulbs and nerves. 
 
 The temporal lobes project above this surface behind like 
 large tubercles, one on each side, and are separated from 
 each other by a considerable interval. They are divided from 
 
THE CEREBRUM. 
 
 13 
 
 the frontal surface, or lobes, by the fissures of Sylvius which 
 arch around and constrict their bases. 
 
 The posterior, or occipital lobes, are directed backwards, 
 are pointed posteriorly, and are separated from each other by 
 the posterior median fissure, which in this situation, longitudin- 
 ally, is about three inches in depth, running forward as far as 
 the posterior border of the corpus callosum. 
 
 The contour presented by a view of the under surfaces of the 
 temporal and occipital lobes is oval, concave from before 
 backwards and from side to side, forming a shallow cup, in 
 the center of which is an oval opening. This opening 
 is the hilus of the cerebrum w^hich transmits the cerebral 
 peduncles in front, and behind lodges the optic lobes, or 
 corpora quadrigemina. In front of this opening, between the 
 temj^oral lobes, is an interspace, the iioor of which contains 
 the optic commissure, iufundibulum, corpora albicantia and 
 posterior perforated space. These parts rest upon the body 
 of the sphenoid bone. The posterior median fissure extend- 
 ing backward completes the division of the surface into lateral 
 halves. 
 
 The anterior portions of this surface, or the temporal 
 lobes, are lodged in the temporal fossae of the skull, and the 
 occipital lobes rest upon the tentorium cerebelli. This sur- 
 face behind forms the upper boundary of the extra ventricular 
 portion of the great transverse fissure or fissure of Bichat. 
 
 The cerebrum is divided into lateral halves, called hemis- 
 pheres, by the great longitudinal fissure, which includes the 
 anterior and posterior median fissures that separate the frontal 
 and the occipital lobes. The hemispheres are united at the base 
 of the cerebrum, and by several commissures the largest of 
 which is the corpus collosum or the great transverse commis- 
 sure of the cerebrum. 
 
 'issiirc of Sylviu 
 Figs. 3-7-16-24. 
 
 Occipital lobe 
 posterior nn 
 fissure. 
 
 Hilus of cerebrum 
 and of the hem- 
 ispherical gansli- 
 
 and i 
 
 -issure of Bichat 
 in Fig. 2 bounds 
 the hilus on its 
 sides and behind. 
 The ventricular 
 extremity. Figs. -1 
 Its infer- 
 
 Fig. 17. 
 n called 
 
 Corpus callosum. 
 Figs. 3 S 23-26 
 
Compare convolu 
 tioiis and iissures 
 Fiss. 16 with 2< 
 
 14 ARCHITECTURE OP THE BRAIN. 
 
 In general contour and markings the lateral halves of the 
 cerebrum are alike, but upon closer inspection, the convolu- 
 tions and fibsures of one hemisphere do not correspond with 
 and 17 with 26. those of the other, and in a comparison of any number of 
 brains, there cannot be found any exact resemblance in the 
 hemispheres of the same side. 
 
 There are, however, certain distinct fissures and convolu- 
 see description of tious which cuable the anatomist to map out the surface 
 
 hemispherical ^ 
 
 gaigiion. of the brain, and to define localities which may be com- 
 
 pared with those of other brains. The whole surface of 
 the brain is divided into general regions which correspond to 
 and are named after the bones of the skull which cover them. 
 Thus we speak of the frontal, parietal, occipital, temporal, 
 temporo-sphenoidal, orbital and insular regions of the brain, 
 and that which lies in apposition with its fellow within the 
 longitudinal fissure, as the inner or fissural region. 
 
 The convolutions upon the surface of the cerebrum will 
 be described later on with the hemispherical ganglion. 
 
 STRUCTURE OF THE CEREBRUM. 
 
 In a general description of the anatomy of the cerebrum, 
 it may be said to arise by two peduncles, the parts of which 
 are derived in front from the pons Variolii, and behind from 
 the cerebellum. Each peduncle is about five-eighths of an 
 inch in length, about one inch in breadth from before back- 
 wards, and about three-fourths of an inch in thickness in a 
 lateral direction. The peduncles are separated from each 
 other in the median lines by a thin layer of antero ■ posterior 
 fibres called the raphe. 
 
 One third of the distance from the posterior median line, on 
 the outer surface of each crus, is a vertical depression leadins; 
 
 Jeniculate bodies. ' ^ ° 
 
 Figs, v-8-9-12-13 upwards from the pons to a tubercle, the internal geniculate 
 
 and vertical sec- J- -^ ' o 
 
 tions Nos. 20-21- 'body. lu frout of this depression is a broad band of coarse 
 
 Peduncles of ce 
 brum. Figs. 2 
 8'9-10-S6-27. 
 
 : of pedunc 
 Figs. 26-27 
 
THE CEREBRUM. 
 
 15 
 
 fibres, the crusta, which is directed upwards aud back- 
 wards to the lower margin of the optic tract that 
 marks the upper boundary of the cerebral peduncle. Behind 
 the vertical depression is an oblique tract of finer fibres hav- 
 ing the same direction as those of the crusta and extending 
 upwards to the testes, and to a horizontal tract which is 
 directed outwards from the testes to the internal geniculate 
 body, the brachium posterius The oblique tract behind the 
 depression arises apparently from the pons Varolii, but sub- 
 sequently will be traced to the anterior column of the spinal 
 cord. This tract is depressed below the level of the 
 crusta and overlaps a large band of horizontal anterio- 
 posterior fibres derived from the cerebellum, the pro- 
 cesses e cerebello ad testes (a misnomer). 
 
 ^\^Q processus (a name which we will continue to use in place 
 of the former) of one side is connected with that of the other 
 along their internal margins by the valve of Vieussens which, 
 together with the processes, forms the roof of the fourth ventri- 
 cle. The crustse diverge as they pass upwards from the pons and 
 are separated in front by a wide interval, the interpeduncular 
 space. This interval between the crustte in front is triangular 
 in shape, pointed below, and is about a half an inch in depth 
 above the pons. Two round white eminences, the corpoT-a 
 albicantia, are situated between the peduncles about half an 
 inch in front of the pons Varolii. The third nerves 
 spring from the inner margin of the crustse immedi- 
 ately above the upper border of the pons. The crustse are 
 about a quarter of an inch in thickness, and the nervous mass 
 enclosed and supported by them, composed of numerous 
 tracts and masses of white and gray matter, is called the 
 tegmentum. The crustte are the motor tracts and expand 
 above bodily into the internal capsules of the cerebral heniis- 
 
 ;rusta. Figs. 2-7--8 
 9-I0-I1-13 15-21- 
 S2-23 37. 
 
 Vertical depression 
 on the side of the 
 peduncle. Fig. U. 
 
 stes.bra 
 leal gla 
 
 Figs. 6-1 
 14-26-27. 
 
 Figs. 8-9-11-12 13 
 
 9-10-11-12-13 N- 
 15-27-28-21* to 2;j* 
 
 infundibulu 
 Fig. 9. 
 
 Crust^E and teg- 
 
16 
 
 ARCHITECTURE OF THE BRAIN. 
 
 Tracts 
 
 turn. 
 
 nternal capsule 
 Figs. 4 to 14, 18 t< 
 23, 10* to 19*. 
 
 internal capsule. 
 Figs, 3 8-18*-19'. 
 
 Triangular space 
 enclosed by cor- 
 pus callosum and 
 internal capsule. 
 Figs, 8. 16* to 19*. 
 
 pheres, passing directly through them to reach the motor 
 areas above upon the sides of the suiface of the brain. The 
 tegmentum cojitains the sensory tract, and, with one excep- 
 tion, the fillet, its fibrous structures are interrupted by masses 
 of grey matter before entering the internal capsule to be dis- 
 tributed to the surface of the brain. In a section of the 
 peduncles the tegmentum consists of all that portion of the 
 surface except the divided tracts of the crustse, which are 
 situated on the sides and the front of the peduncles. 
 
 The anatomy of the peduncle will be examined more closely 
 later, but at present it is necessary to mark the distinction 
 between the crusta and the tegmentum, because these divisions 
 of the crus cerebri or peduncle are frequently referred to in 
 works upon anatomy. 
 
 The internal capsule of each hemisphere is derived from 
 the expansion of a crus or peduncle of the cerebrum. The 
 fibres of the crus cerebri pass upwards and outward 
 to about the middle of the hemisphere, where they decussate 
 with the fibres of the corpus callosum, external to and above 
 the outer border of the lateral ventricle. Beyond the decus- 
 sation of these tracts, which extends from before backwards 
 throughout the length of the outer margin of lateral ventricle, 
 the fibres of the corpus callosum and internal capsule inter- 
 mingle with those of the longitudinal commissures of the hem- 
 isphere and constitute its white substance, or the corona radiata. 
 
 The corpus callosum is the great transverse commissure of 
 the brain. It forms the roof the lateral ventricles, and uniting 
 upon its sides with the fibres of the internal capsules, a 
 triangular space is enclosed containing the ventricles and the 
 internal basal ganglia. 
 
 A vertical section across the middle of the brain shows 
 the internal capsule below its junction with the corpus cal- 
 
THE CEREBRUM. 17 
 
 losum to be in relation with internal and external masses of 
 grey matter, the basal ganglia. Those on the inside, are 
 the caudate nucleus, and below it the thalamus opticus; 
 upon the outside of the capsule are the three divisions of Lenticuia, > 
 
 Figs. 9, 12 
 
 the lenticular body, the corpus lenticularis which is bounded 
 externally by the external capsule, claustrum and insula suc- 
 cessively. Above the decussation of the internal capsule 
 and the corpus callosum is the white substance of the brain, 
 the corona radiata, composed of three layers ; an ex- ^a ers ot 
 ternal or sub-con volutional, a middle or the layer of the '"l-^^t""' ^ 
 longitudinal commissures, and an internal or capsular layer 
 which immediately surrounds the ventricle. 
 
 The mass of white matter constituting the corona radiata 
 is surrounded by a sheet of grey matter which extends along 
 the surface of the convolutions and into the depths of the 
 sulci upon the surface of the cerebrum. This lamina of 
 grey matter covering the hemispheres constitutes the hemis- 
 pherical ganglia and is the seat of consciousness, memory 
 and mind. 
 
 The foregoing general description has prepared us to con- 
 sider each part of the cerebrum more particularly as it appears 
 in the order of dissection. 
 
 splierioalgan 
 n. Figs. 16 17 
 
DISSECTION. 
 
 Fig. 3-8. 
 
 By separating the sides of the longitudinal fissure between 
 the hemispheres of the cerebrum, there is brought into view 
 Corpus caiiosum. ^ broad baud of transverse fibres, the corpus callosum, which 
 connects the hemispheres. Enclosing the corpus callosum 
 behind, above and in front is a long continuous con- 
 volution, the gyrus fornicatus, which overlaps it on each 
 side as far as the middle line. The fissure between tlie corpus 
 callosum and the gyrus fornicatus is about five-eights of an 
 inch in depth, extending in a lateral direction from the bot- 
 tom of the longitudinal fissure, and is sometimes called the 
 ventricle of the corpus callosum. 
 
 If the convolutions above the corpus callosum are gently 
 lifted and torn outward, they will break externally from an 
 elevated crest, one on each side, which is the line of decussa- 
 tion of the corpus callosum with the internal capsule as it 
 ascends from the crus cerebri. These crests extend longi- 
 tudinally along the middle of the hemispheres to near their 
 extremities, are more elevated in the center than at each end, 
 and are more widely separated behind than in front. The 
 crests project upwards as longitudinal ridges that form the 
 outer boundaries of the corpus callosum. The upper surface 
 of the corpus callosum is concave from side to side forming 
 a broad longitudinal groove, or trough about four inches in 
 length and two inches wide, situated in the middle of the 
 cerebrum. 
 
 External to the corpus callosum on each side is the white 
 substance of the brain, the corona radiata, divided in front 
 
DISSECTION. 
 
 19 
 
 aii<l behind into two parts by the anterior and the posterior 
 median fissures. It is fringed by a thin layer of grey matter 
 upon its outer border, and the broken surface shows the 
 ends of torn blood vessels, the puncta vasculosa. 
 
 The whole surface exposed by breaking the upper part of 
 the cerebrum to a level with the corpus callosum is oval in 
 shape, and convoluted on its margin by fissures. One on 
 each side is deep, and situated behind the middle of the 
 hemisphere, the posterior extremity of the fissure of Sylvius. 
 Behind the corpus callosum is the exposed upper surface of 
 the cuueus lobe of the brain, the center of vision, and the 
 convolution immediately behind the fissure of Sylvius is the 
 center of word memories. 
 
 To illustrate the structure of the corona I'adiata a triangle 
 has been figured upon the right side of figure 3, which 
 serves to elucidate the phenomena of word blindness, word 
 deafness, amnesia and aphasia, also another triangle in front, 
 to illustrate cerebral automatic action. The external side of 
 the triangle represents the outermost layer of the corona 
 radiata which is composed of fibres passing between 
 adjacent lobes and convolutions. These are called the 
 internuntial fibres, and in the illustration the tract is repre- 
 sented through which the name is suggested by the object, 
 and vice versa, and the fingers are set in motion automatically 
 by aural and visial impressions. 
 
 The internal and anterior sides of the triangle represent 
 the fibres of the external longitudinal commissure which 
 associate the memory centres behind with the seat of the 
 intellect in the anterior lobes, and with the motor centres of 
 the central region of the brain. The former for the produc- 
 tion of conscious and rational, and the latter for subconscious 
 ov automatic action. It is easy to determine the results pro- 
 
 Puncta 
 
 Fig.; 
 
 Figs. 
 
 ntial fibres 
 3 and 18 tt 
 
20 ARCHITECTURE OF TPIE ERAIIf. 
 
 duced u]3on memory, mind and action by the destruction 
 of a nerve centi'e, or the interruption of any of these tracts 
 by accident or disease. 
 
 The internal layer of the corona radiata is that next to 
 and including the crest or decussation of the corpus callosum 
 and internal capsule. This layer of the corona lies close to 
 the walls of the lateral ventiicle previous to its distribution. 
 External to this layer, the fibres of the several layers are 
 mingled into a network, the formatio reticularis of the cere- 
 brum. The internal layer is composed wholly of fibres from 
 the corpus callosum and the internal capsule, and as they pass 
 toward the sui'face of the brain are disposed in horizontal 
 laminae between which the fibres of the longitudinal commis- 
 sures are inserted in their passage from before backwards. The 
 outermost layer of the corona radiata is a close network of 
 fibres passing in all directions and therefore in dissection breaks 
 into short pieces immediately beneath the convolutions. The 
 three layers of the corona may with propriety be called, 
 from within outwards, the capsular, commissural and inter- 
 nuntial layers. These layers are exhibited in plate No. 25 
 of the vertical sections. 
 Dngitudinai com- The LONGiTUDiisrAL COMMISSURES. — The longitudinal fibres, 
 i'or'o'"'comm'ir- ov commissures of the hemispheres, are probably scattered 
 ferior°of Vor'X tlirough tho eutlro mass of the corona, but in some situations 
 p'i'gs'^sT'g'is to they can be demonstrated with ease and the fibres separ- 
 ated for long distances. A tract running parallel with the 
 bottom of the fissure of Sylvius, beneath the insula, is of 
 Mernai ion"itu- cousiderablc size, and is called the external longitudinal 
 commissure. This commissure is represented in the triangle 
 just described, and terminates in the internal capsule in front 
 of the lenticular body. Another commisui-e is situated in 
 the gyrus fornicatus upon the inner side of the crest and 
 
 sure. Figs. 19 
 20 21. 
 
DISSECTION. 
 
 21 
 
 resting within the outer margin of the corpus callosum. It 
 is the superior longitudinal commissure, or the commissure of 
 the gyrus fornicatus. 
 
 The raphe and stbije longitudinales. — In the middle line 
 upon the upper surface of the corpus callosum is a slight 
 linear longitudinal depression, the raphe, and upon each 
 side, and parallel to it, are two longitudinal white lines, 
 the striae longitudinales, or the nerves of Lancisi. The 
 anterior fibres of the corpus callosum are arched forward into 
 the frontal lobe, the middle fibres are transverse, and the 
 posterior form a broad arch behind and are directed back- 
 wards beneath the posterior cornua of the lateral ventri- 
 cles to be distributed to the occipital, basalar and temporal 
 convolutions. The fibres of the corpus callosum decussate 
 continuously with those of the internal capsule above the 
 outer margin of the lateral ventricle and the roof of the pos- 
 terior cornu, forming the crest. The posterior margin of the 
 corpus callosum is thick, is inverted beneath the posterior 
 edge of the fornix, to which it is attached and is called the 
 splenium. 
 
 The splenium forms a part of the upper boundary of the 
 intraventricular portion of the transverse fissure of Bechat. 
 
 The anterior margin of the corpus callosum is arched 
 downwards to the base of the brain, where it divides into 
 two peduncles that diverge outward obli(|uely across the 
 anterior perforated spaces of opposite hemispheres to termin- 
 ate in the anterior part of the temporal lobe upon each side. 
 At their angle of divergence they bound tlie lamina cinerea 
 in front. The downward deflection of the corpus callosum is 
 called its genu or knee. 
 
 A vertical section of the corpus callosum shows that it is 
 about double in thickness in front and behind than in 
 
 Superior 1 
 dinal comr 
 Figs. 3 S3. 
 
 Raphe and 
 longitudil 
 Fig. 3. 
 
 Spleniu 
 5-26. 
 
 Anterior peduncle 
 of corpus callc 
 
22 
 
 ARCHITECTURE OF THE BRAIN. 
 
 Septum lucidum. 
 Figs. 4-5-6-8-10- 
 2li (S.L.) 
 
 Lateral ventricles. 
 Fig. 4. 
 
 :ornua of the lat- 
 ral ventricles. 
 Fig. 5. 
 
 the middle, and in separating its fibres, the inferior layer 
 is observed to be turned downward at its lateral extremi- 
 ties into the caudate nucleii, while the upper fibres pass 
 upward into the crest on either side. The under surface 
 of the corpus callosum forms the roof of the lateral ventri- 
 cles and is attached below along the median line from before 
 backwards, behind to the fornix, and in front to the septum 
 lucidum. Its attachment to these parts bounds the lateral 
 ventricles internally and separates them from each other. 
 
 The removal of the corpus callosum exposes the lateral 
 ventricles, except the middle and posterior cornua which are 
 uncovered by a section of the temporal and occipital lobes. 
 The cavities thus exposed together present a broad depressed 
 surface between the internal capsules. These project upward 
 and outward, and form its outer boundries on each side for 
 two-thirds of the distance in front. 
 
 Projections of the lateral ventricles extend into the anter- 
 ior, middle and posterior lobes of the cerebrum, and are called 
 the anterior, middle and posterior cornua of the lateral ventri- 
 cles. The anterior cornua are directed forward and outward, 
 the middle backwards, outwards, downward, forward and in- 
 ward, encircling the crura of the cerebrum and upon the floor of 
 each is a rounded longitudinal eminence, the hippocampus 
 major which terminates below in a broad convoluted extremity, 
 the pes hippocampi. The posterior cornu is directed outward, 
 downward, backward and inward, and projecting from its in- 
 ternal wall is a longitudinal eminence, the hippocampus minor. 
 An oval eminence is situated externally at the junction of the 
 middle and posterior cornua and is called the pes accessorius, or 
 eminentia collateralis. Behind the reflection of the internal 
 capsule, as it bends downward into the roof of the middle 
 cornu, is a broad groove, directed outwards and downwards, 
 
DISSECTION. 
 
 23 
 
 Foramen of Mom 
 Figs. 4-5. 
 
 which is the common communication between the middle and 
 posterior cornua with the body of the hxteral ventricle. 
 
 The parts seen upon the floor of a lateral ventricle, from 
 before backwards, are the caudate nucleus, the ta3aia semi- 
 cii'cularis, a poi'tion of the thalamus opticus, the choroid 
 plexus, corpus fimbriatum and the fornix. Between the 
 anterior pillars of tlie fornix and the anterior extremity of 
 the thalamus is an oval opening through which the lateral 
 ventricle communicates with the third ventricle, and with 
 the lateral ventricle of the opposite side. This opening 
 transmits the choroid plexus of one ventricle to be contin- 
 uous with those of the others, and is called the foramen 
 of Monro. Extending backwards from the foi'amen of 
 Monro, beneath the corpus fimbriatum or edge of the fornix, 
 as far as the apex of the middle cornu of the lateral ventri- 
 cle, is a narrow fissure which transmits the velum interposi- 
 tum to the lateral ventricle. Tliis fissure is called the fissure 
 of Bichat, and is the ventricular termination of the great 
 transverse fissure. 
 
 The fornix is a triangular layer of longitudinal white 
 fibres, with its apex directed forward and its base attached 
 behind to the posterior extremity of the corpus callosum. 
 Its anterior extremity divides into two rounded cords, one on 
 each side, which descend in front of the thalamii optici to 
 the base of the brain, and obliquely backward to the cor- 
 pora albicautia in the interpeduncular space, and fi-om these 
 latter are tracts of white fibres passing outward to the internal 
 capsules. 
 
 The apex of the fornix is continued forward to the 
 genu of the corpus callosum in the median line, by a septum uindum. 
 
 ^ _ . Figs. 4-5-6 8-26. 
 
 thin membrane, the. septum lucidum. This membrane 
 fills up the interval between the fornix and the genu of 
 
 Fissure of Bichat 
 Figs. 4-5. 
 
24 
 
 AECHITECTUEE OF THE BRAIN. 
 
 Fifth ventri 
 
 cle. 
 
 
 Figs. 4-8. 
 
 
 
 Genu of the 
 
 internal 
 
 capsule. 
 
 Figs. 
 
 4- 
 
 Corpus fimbriatum 
 and posterior pil- 
 lars of fornix. 
 Figs. 4-5. 
 
 Ungual convolii 
 tion. Fig. IT. 
 
 Foramen Monro. 
 
 the corpus callosum dividing the lateral ventricles from 
 each other. The fibres of the septum lucidum pass in 
 a longitudinal direction from the fornix to the corpus callos- 
 um. The septum is composed of two layers, side by side, 
 enclosing a vertical slit, the fifth ventricle. The posterior 
 angles of the fornix are extended outward, backward, and 
 downward along the broad groove behind the arch or genu of 
 ■the internal capsule, to be continuous with the layer of white 
 fibi'es which cover the floor of the middle and posterior 
 cornua. These extensions are called its posterior pillars, 
 each pillar apparently dividing to form the hippocampus 
 major and minor of the same side. The edge of the fornix 
 is called the corpus fimbriatum, and rests upon the thalamus 
 opticus. It extends behind the posterior extremity of the 
 thalamus downward along the internal margin of the floor of 
 the middle cornu and terminates in the apex of the ungual 
 convolution. 
 
 The choroid plexus is a capillary network lying upon the 
 thalamus and attached to the edge of the velum interpositum, 
 from which it receives the blood vessels that supply it. It 
 extends from the foramen of Monro in front over the 
 thalamus opticus into the middle cornu of the lateral ventri- 
 cle. It lies parallel with the fissure of Bichat and the corpus 
 fimbriatum to their lower extremities, which terminate at the 
 apex of the middle cornu. The choroid plexuses of the 
 lateral ventricles and those of the third ventricle are con- 
 nected through the foramina of Monro. 
 
 The fornix forms the roof the third ventricle. If it is 
 divided transversely and its parts reflected, its anterior 
 pillars will be seen descending in front as two rounded cords; 
 and upon the under surface of its posterior part, crossing in 
 lateral direction, are several trausv^erse stride called the lyra. 
 
DISSECTION. 
 
 25 
 
 These Jatter are fibres of the corpus callosum crossing in a 
 transverse direction beneath the attachment of the posterior 
 margin of the fornix to that of the corpus callosum. 
 
 Beneath the fornix, and exposed by its removal, is a pro- 
 cess of pia mater extending into the ventricles of the brain, 
 and called the velum interpositum on account of its being 
 interposed between the fornix and the third ventricle, which 
 is beneath it. The velum interpositum is triangular in shape, 
 corresponding to the under surface of the fornix, with which 
 it is in contact. The velum contains numerous blood vessels 
 which supply the choroid plexuses. Near its centre, side 
 by side, are two large veins, the vena Galeni, which receive 
 blood from the venae corpora striata and convey it to the 
 straight sinus, at the junction of the falx cerebri and tentor- 
 um cerebelli. Suspended along the middle line upon the 
 under surface of the velum are two fringes, the choroid 
 plexuses of the third ventricle, which are continuous with 
 those of the lateral ventricles at the foramina Monro. The 
 velum is derived from the pia mater covering the occipital 
 and temporal lobes of the brain. It is admitted into the third 
 ventricle beneath the posterior border of the corpus callosum, 
 and passing forward under the fornix, beneath its lateral mar- 
 gins, it extends into the lateral ventricles through the fissures of 
 Bichat. At the outer sides of the cruri cerebri, the pia mater 
 passes directly from the under surface of the brain into the 
 middle cornua of the lateral ventricles upon each side. This 
 membrane embraces the pineal body, and the latter may be 
 torn off by its careless removal. The parts exposed by 
 its removal are, the cavity of the third ventricle, pineal 
 body, optic lobes and the thalamus. These, together with 
 the basal ganglia and internal capsule, will now be described 
 together, in order that their relations may be more clearly 
 
 directly 
 lateral 
 
 surface of t h ^ 
 
 Figs. 5-17 
 
 xposed by 
 jmoval of 
 lum. Fig. 0. 
 
!tion repre- 
 ed by higs. 
 
 26 ARCHITECTURE OF THE BRAIN. 
 
 understood. The removal of the cerebellum, as seen in Fig. 
 8, is advantageous to this dissection, as the parts above men- 
 tioned are then seen in connection with those below. 
 
 In general, this dissection presents a median longitudinal 
 
 ^"'' depression, and two lateral masses, one on eacli side. In the 
 
 middle line, between the lateral masses, is a longitudinal 
 
 cleft, the third ventricle. The third ventricle is one and half 
 
 an incli in length, extends vertically to the base of the brain, 
 
 Floor of third ven- ^^]lere its floor is formed by the parts contained in the inter- 
 
 tricle. Fig. 7-9. •' ■>■ 
 
 peduncular space, including the lamina cinerea, optic commis- 
 sure and tuber cinereum. Communicating with the ventricle 
 below is a canal leading to the pituitary body, the infundi- 
 bulum. The pillars of the fornix descend in the anterior 
 extremity of the third ventricle. By separating the anterior 
 Anterior commis- jiillars of the forulx the middle portion of the anterior com- 
 
 snre. Figs. 6-13- 
 
 14-21-23 23-14*- mlssurc is exposed, and is seen crossing the anterior wall of 
 the ventricle in front of them. The anterior commissure of 
 the third ventricle is directed outward and backward on each 
 side to the extremity of the inferior ramus of the internal 
 capsule of the hemisphere, its extremities terminating in 
 the temporal lobes. It is supposed to be the commissure 
 of the centres of smell and taste. The internal surfaces 
 of the thalami form the lateral walls of the third ventricle. 
 Crossing its middle, uniting the central part of one thalamus 
 wilh that of the other, is a broad gray commissure, the mid- 
 dle or gray commissure of the third ventricle. The ventricle 
 is pointed behind, and is continuous with a canal which passes 
 backwards be^ieath another transverse band of white fibres, 
 the posterior commissure of the third ventricle. The canal 
 just mentioned leads downwards and backwards, beneath the 
 posterior commissure and the commissure of the corpora 
 quadrigemiua and valve of Vieussens, to communicate with 
 
 Third ventricle 
 
'-33 33. 
 
 Ileal Kland and 
 pillars. Figs. 6-». 
 
 DISSECTION. 27 
 
 the fourth ventricle. This canal is called the aqueduct of 
 Sylvius, or the iter e tertio ad quartern ventriculum, or, for 
 short, the iter. Extending from the anterior pillars of the The iter. Figs. 215- 
 fornix forward to the genu of the corpus callosum, and sep- 
 arating the lateral ventricles, is the septum lucidum. 
 
 Behind the posterior extremity of the ventricle, and 
 above its posterior commisure, is a small globular body some- 
 what elongated from before backwards, the pineal gland. 
 Two delicate white tracts extend forward from the anterior 
 extremity of the pineal gland, one on each side, upon the 
 lateral margins of the third ventricle, they are the anterior 
 pillars of the pineal gland and mark the division between the 
 superior and internal surfaces of the thalamus. These tracts are 
 lost in front of the anterior extremity of the thalamus, where 
 they are in conjunction with the descending anterior pillars 
 of the fornix. The anterior extremity of the pineal gland is 
 attached to the upper surface of the posterior commissure of 
 the third ventricle by a delicate membrane, whose lateral 
 margins are thickened and called the posterior pillars of the 
 pineal gland. The posterior margin and sides of the pineal 
 gland are free, and it rests above, in front of, and between 
 the anterior tubercles of the corpora quadrigemina. 
 
 The corpora quadrigemina or optic tubercles are four 
 small bodies placed above and between the cruri cerebri, and 
 in the interval between the posterior extremities of the thalami 
 optici. They are enclosed behind by a notch upon the 
 anterior part of the cerebellum the incisura anterior. The 
 corpora quadrigemina are in pairs, an anterior pair, the nates, 
 and a posterior pair, the testes. The tubercles of each pair 
 are placed one on either side of the median line and are connect- 
 ed by a commissure.Directed obliquely outward and forward 
 from the nates and the testes, on either siile, are two bands 
 
 Corpora quadrige 
 
28 ARCHITECTUEE OF THE BRAIN. 
 
 ^'9-13-H ^'^^''^^' of white fibres, the brachia,anteriiis and posterius, the former 
 being connected with the nates, and the latter with the testes. 
 These tracts are the external margins of the horizontal layers 
 of fibres which pass from the corpora quadrigemina, beneath 
 the posterior extremity of the thalamus, to the internal capsule. 
 They are also connected with the posterior extremities of the 
 optic tract and geniculate bodies, the brachium anterior with 
 the corjous geniculatum externum and the brachium posteri 
 with the corpus geniculatum internum. Behind the corpora 
 cpiadrigimina, and covered by the cerebellum, are two broad and 
 rounded cords, one on each side, which ascend from the hilus 
 of the cerebellum and are the processes, or the superior 
 peduncles of the cerebellum. These are united along their 
 inner margins by a thin translucent membrane, which is de- 
 pressed upon its upper surface, and is called the valve of 
 
 Processes and Vlcussens. Tlic valvc Is polntcd at its anterior extremity 
 
 valve of Vieus- -*■ */ 
 
 ms 26^3oV^^" ■^liich projects upwards between the testes, and is elevated 
 above the general surface. On each side of its anterior extrem- 
 ity are the apparent origins of the fourth nerves. The under 
 surface of the valve and of the processes form the roof of the 
 Superior and infer- fourth veutriclc. Tho supcrlor vermiform process of the 
 
 processes of cere- cerebcllum rcsts upon the valve of Vieussens and the infer. 
 
 30-31. ior vermifoi'm process is beneath it in the fourth ventricle. 
 
 Upon the outer surface of each processus at its anterior part, 
 crossing it obliquely in an upward direction, is a band of 
 fibres parallel to those of the crusta from which it is divided 
 by the sharp vertrical furrow previously mentioned. This 
 band of fibres terminates above in the testes and brachium pos- 
 terior, and below it is continuous with the fundamental root 
 zone of the spinal cord. 
 
 At the upper extremity oi the depression between the 
 
 Corpus genicula- '^ '- •' ■■■ 
 
 turn internum, crusta aud the tract iust mentioned is a tubercle, which is 
 
 Figs. 7 8-9. ■> ' 
 
Figs. 13-14. 
 
 8 9-10, 10* to 18*. 
 
 DISSECTION. 29 
 
 connected behind with the brachinm posterius, and in front 
 with the lower division of the optic tract, and is called tlie 
 corpus geniculatum internum. External and above the corpus 
 geniculatum internum, upon the outer division of the extrem- 
 ity of the optic tract, is an elevation, the corpus geniculatum corpus genicuia 
 externum. These bodies are apparently the outer terminations '''S"- "-^ '■•• 
 of the brachia, but, as before stated, the major part of the 
 fibers of the brachia passes beneath the thalamus and optic connection of t 
 tract to the internal capsule. int'lniTi "Ipsuie 
 
 The basal ganglia: — Upon each side of the third ventricle, 
 resting upon the upj)er extremities of the peduncles or cruri 
 cerebri, are two large masses of gray matter, one on each side, 
 the basal ganglia of the cerebum. Each mass is composed of 
 three large ganglia, two of which are internal, and one exter- 
 nal to a broad and thick layer of white fibres, the internal 
 capsule. The capsule is seen projecting above, from between 
 the external and internal ganglia, as an elevated tract com- 
 posed of transverse lamina or bundles of fibres. The fibres 
 of the antei'ior portion of either internal capsule are directed Distribution of the 
 
 internal capsule. 
 
 forward toward the anterior lobe of the cerebrum, the middle Figs. 7-9-13. 
 fibres upwards to the parietal region, and the posterior backwards 
 and outwards into the occipital and temporal lobes of the brain. 
 The internal capsule radiates like the pinna of the ear, an 
 interspace being left opposite the anterior perforated space interspace in cap- 
 between the frontal and temporal lobes of the hemisphere. i8to2o.''' 
 In consequence of this disposition of the fibres of the capsule, 
 it encloses a conical concavity, open externally, which is filled 
 by a mass of gray matter, the lenticular nucleus, or external Lenticular nucleus 
 basal p-anojlion. fumei. Figs. 7- 
 
 At its posterior part, the internal capsule sweeps around an 
 •abrupt curve as it descends to form the roof of the middle 
 cornu of the lateral ventricle. The ]-eflected portion of the 
 
CaudalB ni 
 FiKS. 4 -6- 
 11« (N C) 
 
 30 ARCHITECTURE OF THE BRAIN. 
 
 capsule is distributed to the temporal lobe and its abrupt 
 deflexion behind is called its genu. 
 
 The INTERNAL BASAL GANGLIA : — The internal basal ganglia 
 rest upon and are attached to the internal surface of the 
 internal capsule. They are separated from each other by a 
 depression, and a narrow band of white fibres, the taenia 
 semicircularis. The superior internal ganglion, or caudate 
 nucleus, rests upon the upper portion of the internal surface 
 of the internal capsule, and projects into the floor of the lat- 
 eral ventricle. Its anterior portion, or body, is large, and 
 occupies the anterior cornu of the lateral ventricle. Tlie pos- 
 terior part or tail of the caudate nucleus gradually tapers 
 from the body in front to form a narrow elevation which 
 runs along the outer margin of the lateral ventricle, and, 
 bending beneath the genu of the internal capsule, enters the 
 roof of the middle cornu, at the end of which it terminates 
 in a bulbous extremity. 
 
 The taenia semicircularis is a narrow band of white fibres 
 at the bottom of a depression which separates the caudate 
 nucleus from the thalamus opticus. It extends along the 
 whole length of the lower margin of the caudate nucleus. 
 Beginning in front immediately anterior to the anterior pillars 
 of the fornix as a broad surface, it extends backward as a 
 narrow band which terminates below at the end of the middle 
 cornu and is attached to the apex of the ungual convolution. 
 
 The taenia semicircularis in the floor of the lateral ven- 
 Fig.\ ^"^ ^""' tricle has the appearance of a narrow band of white fibres, 
 but, when the caudate body is removed, it is seen to be the 
 margin of a tract of fibres which is derived from slips emerg- 
 ing from between the lamina of the internal capsule to 
 increase its volume as it passes forward beneath the caudate 
 nucleus. 
 
 Derivatii 
 
 Lefl 
 
DISSECTIOT^. 
 
 31 
 
 The thalamus opticus: — The inferior internal ganglion, oi' 
 thalamus opticus, in general outline is fusiform in shape. Its 
 body is somewhat elongated, and a transverse section shows 
 that it is prismatic. Its upper surface is divided into two 
 portions by an oblique depression which begins in front 
 behind the anterior pillar of the fornix, and extends backward 
 and outward to its external margin at the genu of the internal 
 capsule. The surface above and external to this depression 
 forms a part of the floor of the lateral ventricle. The por- 
 tion below or internal to the depression is covered by the 
 fornix, and is continuous behind and below the crus cerebii 
 with the outer division of the optic tract. The internal sur- 
 face of the thalamus forms the lateral wall of the third ven- 
 tricle, and in the middle of the ventricle, is united to the thal- 
 amus of the opposite side by the middle or gray commissure 
 of the third ventricle. The inferior surface of the thalamus 
 looks outwards and downwards and is attached to the internal 
 capsule to which it gives off a great mass of fibres, before 
 and behind, forming the anterior and the posterior divis- 
 ions of the internal capsule. A tract of longitudinal fibres, 
 called the fillet, lies external and beneath the lower portion 
 of the inferior surface of the thalamus. 
 
 Upon closer inspection the thalamus will be seen to con- 
 sist of several smaller masses, more or less similar in shape 
 to that of the caudate nucleus. The anterior extremities of 
 these masses, composing the thalamus, are large, and their 
 posterior portions taper into tracts, which pass backwards 
 around the genu of the internal capsule. These bodies are, 
 from within outwards: first, a small body situated at the side 
 of the posterior extremity of the third ventricle, between the 
 pineal gland and the posterior extremity of the thalamus, 
 and connected with the anterior pillar of the pineal gland, 
 
 .n of the thai- 
 ■ to the fillet. 
 10-13-21-22- 
 
 the Thala 
 Fig. 6. 
 
32 ARCHITECTURE OF THE BRAIN. 
 
 called the pison (pea). This body has no posterior exten- 
 
 2. Thepuivinar. sioQ. Secoiid, a fusiform body, beginning in front by a 
 
 pointed extremity above the middle commissure, and rapidly 
 enlarging forms a prominence upon the posterior portion 
 of the thalamus, after which it gradually contracts and is 
 continuous with the external geniculate body and the superior 
 division of the 02Dtic tract. Tliis body is called the pulvinar 
 
 3. Thetubercu- aud Is probablv the vlsual centre of the thalamus. Third, a 
 
 lumthalami. . . 
 
 prominence upon the anterior extremity of the thalamus, in 
 front of the apex of the pulvinar, behind the anterior pillars 
 of the fornix and above the foramen Monro, called the tuber- 
 culum of the thalamus. Extending backward and slightly 
 outward from this tubercle is a tract of white fibres which 
 follows the groove, before mentioned, on the upper sur- 
 face of the thalamus as far as the genu of the internal cap- 
 sule, among the fibres of which it is lost. The tuberculum 
 thalami is supposed to be the basal centre of taste and smell. 
 
 Thefusiformis. Fourtli, extemal to the tuberculum and the tract just de- 
 scribed, and more distinctly seen if the latter is I'emoved, is the 
 largest body composing the thalamus. It is broad in the 
 centre, pointed at each extremity, fusiform in shape, reaching 
 across the upper surface of the internal capsule, and separ- 
 ated from the caudate nucleus by the t?enia semicircularis. 
 This body is supposed to be the thalamic centre of common 
 sensation. Fifth, underneath the central part of the thala- 
 mus, and imbedded in the tegmentum of the crus cerebri, is 
 
 Fig"''"nT3' 14- a round body, somewhat larger than a pea, called the sub- 
 thalmic ganglion, or red nucleus. This body does not prop- 
 erly belong to the thalamus, but is closely associated with 
 it. It is the termination of the anterior extremity of the 
 processus, or supeiior peduncle of the cerebellum, and 
 from it are distributed fibres which pass to the bodies 
 
 Subthalmic 
 ;anglion or red 
 lucleus of the 
 
 15-19*-20*, 
 
DISSECTION. 33 
 
 composing the thalamus under which it lies. The red nucleus pig. ,5. 
 is in relation externally with the iillet, and internally with the 
 continuation of the gray matter which surrounds the iter and 
 lines the wall of the third ventricle. 
 
 The external basal ganglion: — The gray matter external External basai o, 
 
 ° _ -^ lenticular gantjli 
 
 to the internal capsule, and enclosed by its funnel shaped °°- Figs- 9-12-20 
 concavity, is the lenticular ganglion, so called because its 
 parts are disposed in lenticular layers. Its layers are super- 
 imposed and separated from each other by laminae of white 
 fibres, called capsules. A transverse section of the entire 
 mass of the lenticular body, including the parietal and tem- 
 poral portions of the internal capsule, is triangular. The 
 apex of the triangle is directed downward and inward, and its 
 base is opposed to that of the insula. It will be seen that 
 the lenticular nucleus is bounded above and below by the 
 internal capsule and is in three layers or parts. The outer sur- Transverse section 
 
 '^ '' r ^f j,,g lenticuarl 
 
 face of each layer is convex and composed mostly of gray nucleus. Figs n* 
 
 matter, while the inner portion of each section is traversed by 
 
 numerous white tracts for some distance from the septum or 
 
 capsule. The three bodies which comprise the lenticular 
 
 nucleus increase in size and thickness from within outwards. 
 
 The innermost is a conical wedge spreading the fibres of the 
 
 internal capsule at the bottom of its funnel shaped concavity. 
 
 The inner and middle portions are together called the globus 
 
 pallidus, on account of being much paler in color than the 
 
 outermost, which is called the putamen. Externally the 
 
 outer body or portion of the lenticular nucleus is covered by 
 
 a thick layer of radiating white fibres which diverge from 
 
 below upwards. 
 
 The layer of diverging fibres external to and overlying 
 
 ^ ° J » External capsule. 
 
 the lenticular body, forming the external capsule, is thicker Figs. --9 19 io» 10 
 above than below, and is united with the outer surface of the 
 
34 
 
 ARCHITECTURE OF THE BRAIN. 
 
 u,n. Figs. 
 . 1«* (c 1,- 
 
 oiitward. Figs. 5- 
 1d*-16*, betweeu 
 (IC and IC). 
 
 3rusta and tegme 
 turn. Fig. :)2. 
 
 internal capsule above and along the upper margin of the 
 lenticular nucleus The external capsule is covered upon its 
 outer surface by a thin layer of gray matter which is thicker 
 below than above, and is called the claustrum, (a wall,) 
 external to which is the subinsular layer of white matter, and 
 the insula. These parts therefore enclosed by the funnel 
 shaped whorl of the fibres of the internal capsule are, from 
 within outward, the three divisions of the lenticular nucleus, 
 the external capsule, claustrum and tbe white and gray 
 matter of the insula, the latter being enclosed in the Y 
 shaped expansion of the bottom of the fissure of Sylvius. 
 
 The internal capsule will be studied in detail subsequent 
 to the description of those parts below whicb enter into its 
 formation. It is sufficient at this time to remember its 
 shape, its relations to the basal ganglia and that fibres from 
 these ganglia contribute to swell its volume. 
 
 Because of the funnel shape of the internal capsule, a 
 horizontal section of the brain, as generally represented in 
 diagram, shows an anterior and a posterior arm, and locates 
 the motor portion of the capsule behind the knee in the 
 anterior part of the posterior arm. 
 
 The hemispherical ganglion and lateral dissections of it 
 will be described after its internal anatomy has been traced 
 in a longitudinal direction. The crura cerebri or peduncles 
 of the cerebrum, as before stated, consist of two portions, 
 the crusta and the tegmentum. The crusta is a broad band 
 of fibres upon the outer and anterior part of either crus cere- 
 bri. The tegmentum is all that portion of the peduncle 
 behind and internal to the crusta. The crusta originates 
 entirely from the pons Varolii, but the tegmentum is con- 
 nected with the cerebellum and with the posterior layer ot 
 the pons which includes the fillet and fasciculi tei-etes, and 
 
DISSECTION. 35 
 
 through these with the spinal cord. The connections and the 
 relations of the various tracts which comjDose the peduncle of 
 the cerebrum will be more clearly understood after the struc- 
 ture of the cerebellum and the pons Varolii have been studied. 
 We will again return to the anatomy of the cerebrum in 
 order to trace the parts of the peduncle to their connections 
 with those of the hemisphere. 
 
CEREBELLUM. 
 
 ;erebellu 
 6-7 27 t( 
 
 Superior and infer- 
 
 ra anterior 
 posterior. 
 
 Peduncle ( 
 cerebellu 
 8 to l&'A. 
 
 It will not assist ns to the understanding of tlie architec- 
 ture of the central nervous system to enter into a minute 
 description of the external surface and shape of the cere- 
 bellum. Its external appearance and the divisions of its sur- 
 face will be readily understood by a study of the plates in 
 this work. It is sufficient to say that it is composed of a 
 middle and two lateral lobes. The upper portion of the mid- 
 dle lobe is called the superior, and the lower part the inferior 
 venniform process of tlie cerebellum. The superior vermi- 
 form process rests upon the upper surface of the valve of 
 Vieussens, and the inferior vermiform process is beneath the 
 valve, and within the fourth ventricle. The lateral lobes 
 project backwards and outwards, and are large masses sep- 
 arated in front by a notch, the incisura anterior, and behind 
 by a deep and narrow fissure, the incisura posterior. In 
 front of the lower surfaces of the lateral lobes, beneath the 
 lower margin of the pons, are two small lobes, one on each 
 side of the medulla oblongata, called the flocculi. 
 
 The cerebellum is connected with the cerebrum by the 
 processes which are its superior peduncles; with the pons in 
 front by its middle peduncles; and with the spinal cord 
 below by two rounded cordlike bodies, the restiform bodies, 
 or its inferior peduncles. 
 
 A section of the middle lobe of the cerebellum in the 
 median line from before backward, exposes the fourth ventri- 
 cle. The surface of the section presents a beautiful arbores- 
 
CEREBELLUM. 
 
 37 
 
 cent distribution of white matter radiating from the end of a 
 lougitudiual section of the valve of Vieussens the rami from 
 which divide into small branches as they approach the 
 surface. These subdivide into minute stems of white fibres 
 terminating in small leaflets which line the sides of the deep 
 fissures that project inward from the surface of the lobe. 
 The appearance presented by this section is called tlie arbor 
 vitse. 
 
 A section across a lateral lobe, outward and backward, 
 shows within, a large mass of white matter, an arbores- 
 cent border, and imbedded in the anterior part of the while 
 substance a convoluted layer of gray matter surrounding a 
 portion of white substance of irregular shape. This body is 
 called the corpus dentatum of the cerebellum and is its 
 sensory or internal basal ganglion. 
 
 In a properly hardened cerebellum, if the sides of its 
 transverse fissure are separated, and the upper half gently 
 torn from the lower and broken oiF in front, it will be ob- 
 served that the sui'face of either lobe will separate behind 
 and in front over the dentate body, that the fractured 
 fibres are external to this body, and are those of the middle 
 peduncle of the cerebellum. 
 
 The upper surface of the dentate body ia elevated above 
 the remaining portion of the surface thus exposed upon the 
 inferior segment, or lower portion of the cerebellum. This 
 surface presents numerous lines radiating outward from the 
 corpus dentatum, and others directed inward and backward, 
 from the broken middle peduncle of the cerebellum. The 
 fibres from these separate sources commingle to form the 
 corona radiata of the cerebellum. 
 
 It will be observed that the processus, or superior pedun- 
 cle of the cerebellum, of either side passes directly down- 
 
 Figs. 
 
 ate body. 
 
 of thecerebellun 
 Fig. Ib'A. 
 
Figs. 8 9- 
 
 38 ARCHITECTURE OF THE BRAIN. 
 
 ward and backward into the centre of the corpus dentatum, 
 entering its hilas upon the under surface. The lower extrem- 
 ity of the processus, on its outer side, is overlapped by a 
 tract of radiating iibres wliich spring upward from the inter- 
 val between the middle and superior peduncles of the cere- 
 bellum as tbey approach each other. This tract emerging 
 from between the superior and middle peduncles, is the upper 
 extremity of the restiform body, or inferior peduncle of the 
 cerebellum, and is distributed, to the upper surface of the 
 corpus dentatum. 
 
 Tlie attention is directed to the fact, that the corpus 
 dentatum is connected with the superior and the inferior 
 peduncles of the cerebellum, directly associating this body 
 with the cerebrum above, the spinal cord below, and 
 the cerebellum behind. The middle peduncle is composed 
 of two distinct layers of fibres, differing in function, con- 
 nected directly with the gray matter of the surface of the 
 cerebellum and having no connection with the corpus den- 
 tatum. 
 oniparison of the Thus it Is apparent that there is an analogy between the 
 
 beiiumtothoseof structure of the cerebellum and that of the cerebrum and its 
 application at this time will assist us to understand those 
 parts of the pons Varolii and medulla oblongata which are 
 associated in the comparison. 
 
 The sheet of gray matter which covers the surface of the 
 
 cerebellum, and dips into its fissures, is analagous to that 
 
 which covers the hemisjiheres of the cerebrum, and may 
 
 emisphericaisan- thercfore be called the hemispherical a:anglia of the cere- 
 
 glion of the cere- ^ & t> 
 
 bellum. The enclosed mass of white matter, composed of 
 the interlacing fibres of the middle peduncle and the corpus 
 dentatum, constitute the corona radiata of the cerebellum 
 The corpora deutata, associated with tlie sensory tracts of the 
 
 bellu 
 
CEREBELLUM. 
 
 39 
 
 cerebro spinal axis, correspond to the internal basal ganglia 
 of the cerebrum, and, as we shall see subsequently, the 
 external basal ganglia of the cerebellum are displaced, and 
 are located in the pons Varolii. The superficial layer of 
 the pons unites the opposite hemispheres of the cere- 
 bellum, and is the analogue of the corpus callosum of 
 the cerebrum. The deep layers of fibres of the middle 
 peduncles terminate in the gray matter of the pons Varolii, 
 and correspond to the motor tracts of the internal capsules of 
 the cerebrum, and the crustse of the crura cerebri. The 
 superior and inferior peduncles of the cerebellum are inter- 
 rupted in their passage by the corpora dentata, thus they 
 coincide with the tegmentum of the crurse cerebri. The direct 
 connection of the cerebellum with the spinal cord, by means 
 of the direct cerebellar tract and the arciform fibres of the 
 medulla oblongata, may correspond with the fillet of the cere- 
 brum, completing the analogy between these large masses 
 of cerebro spinal axis. Taken together, the superior pedun- 
 cle, the internal portion of the middle peduncle, and the 
 inferior peduncle of the cerebellum, strikingly correspond to 
 the several elements which enter into the formation of the 
 internal capsule of the cerebrum. 
 
 By the use of the above analogy the study of the con- 
 necting parts is made easy. 
 
 Corpora dentata, 
 
 Superficial fibers of 
 
 Deep layer, the 
 tor tract of it 
 
 peduncl 
 respond t 
 
THE PONS VAROLII. 
 
 Description of the The poiis Varolii is a broad and thick band of transverse 
 
 pons V 
 
 fibres crossing in front of the upper continuation of the 
 spinal cord and the medulla oblongata, interrupting the 
 anterior median fissure, and connecting the opposite hemis- 
 pheres of the cerebellum. It is about one inch and a half 
 broad from above dowuAvard, and nearly two inches in a 
 lateral direction. It is contracted upon each side as it 
 approaches the cerebellum, where it forms the middle pedun- 
 cles of that body. Its general shape is oval, and its anterior 
 surface is convex in every direction. A shallow depression 
 crosses its surface, from above downward in the median line, 
 called the basilar groove, which lodges the basilar artery. 
 This portion of the pons is perforated by numei'ous openings 
 for the passage of blood vessels. The upper margin of the . 
 pons is bounded in the middle by the posterior perforated 
 space and laterally by the fibres of the crustse. The third nerves 
 arise from the inner sides of the crustse above this margin. 
 Its lower margin is bounded in the middle line by the anterior 
 median fissure and raphe of the medulla oblongata, and suc- 
 cessively on each side of the fissure, from within outwards, 
 by the anterior pyramid, olivary body, lateral tract, and the 
 Figs. 8-26. restiform body. Behind the pons Varolii is the floor of the 
 
 'loccuii. Figs. 7- fourth ventricle. The flocculi rest upon the outer extremities 
 of its lower border in front of the restiform bodies. The 
 sixth nerve emerges from between the pyramid and the olive, 
 the seventh- and ei2;hth from internal to the flocculus and resti- 
 
 Fourth ventricle 
 
 eighth 
 Figs. 9^ 
 
THE PONS VAROLII. 
 
 41 
 
 form body, and each of these nerves is directed forward 
 beneath the lower border of the pons. The fifth nerve 
 emerges from the middle of the anterior surface of the mid- 
 dle peduncle of the cerebellum. 
 
 The lower fibres of the superficial layer of the pons, 
 which form the lower third of its anterior surface are trans- 
 verse in direction, and are overlapped at their outer extrem- 
 ities by those from above which arch downwards near their ter- 
 mination. The upper transverse fibres are arched upward in the 
 middle and terminate in the lower lobes of the cerebellum on 
 each side. The uppermost fibres of the pons are seen to proceed 
 from the posterior perforated space, and winding close to the 
 cms cerebri on each side are directed backwards to enter the 
 cerebellum above the processes. These latter fibres do not 
 properly belong to the pons Varolii, but are derived from the 
 floor of the fourth ventricle, and passing forward through the 
 raphe connect the gray matter of the fourth ventricle 
 with the cerebellum. They are similar in function to the rest- 
 ifoi'm body of the medulla oblongata and are distributed 
 to the corpus dentatum in conjunction with the inferior pe- 
 duncle of the cerebellum. Other fibres, derived from the 
 floor of the fourth ventricle, enter the raphe and pass down- 
 wards beneath the lower margin of the pons. These emerge 
 in front from the anterior median fissure of the medulla 
 oblongata and winding over the pyramid and olive, in con- 
 junction with the arciform fibres, join the restiform bodies 
 to terminate in the corpus dentatum of the cerebellum. 
 Doubtless, also, there are associated with these, other fibres 
 that correspond to the direct cerebellar tract of the spinal 
 cord, and which will be better understood after this tract 
 has been described. 
 
 The uppermost 
 iibres of the pons. 
 Figs. 9-10. 
 
 Inferior restiform 
 fibres of the floor 
 of the fourth ven- 
 tricle. Figs. 9-10. 
 
Section of the pons 
 
 Plano-concav 
 face of the 
 and th 
 and lenticula 
 section. Figi 
 to 14 26 
 
 42 ARCHITECTURE OF THE BEAEST. 
 
 Structure of the foists Varolii : — The several layers of 
 which the pons Varolii is composed, will be more easily under- 
 i'trdi'vision°ln"o stood by dividing it in the median line from before backward, 
 '"°''°'''°"l into lateral halves. After the cerebellum has been removed, 
 
 Figs. 26-3i-3o. " 
 
 if the pons Varolii is torn in a longitudinal direction along 
 the floor of the fourth ventricle in its posterior median fissure, 
 it will separate into striated sui'faces to the depth of about a 
 quarter of an inch in the middle of the ventricle, and above 
 the pons, between the cruri cerebri, it will divide as far for- 
 ward as the posterior perforated space, and below to the 
 anterior median fissure of the medulla oblongata. The 
 adjacent surfaces, thus separated, will be seen to form each 
 a plaino- concave surface, concave in front and straight upon 
 its posterior margin along the floor of the fourth ventricle. 
 If the remaining portion of the pons is now divided in the 
 median line by the knife, the pons will be separated into 
 lateral halves. The surface, presented by a section of the 
 anterior portion of the pons, is lenticular in shape and covers 
 the anterior two-thirds of the whole surface thus exposed. 
 
 It will be observed that in a division of the pons Varolii, 
 transverse to the fibres on its anterior surface, and longi- 
 tudinal to the cerebro spinal axis, the divided surface presents 
 two distinct portions for examination ; an oval portion in 
 front which is connected with the anterior pyramid of the 
 medulla oblongata, and with the crusta of the crus cerebri ; 
 and behind, a plano-concave surface of radiating fibres, the 
 raphe, which separates the lateral halves of the crura cerebri, 
 the posterior part of the pons, and the medulla oblongata. 
 Raphe. Figs. 11 to 1'he Taphc is composed of anterio-posterior fibres, and is an 
 important structure, because, within it are the decussations of 
 the nerves of the medulla oblongata and the commissures of 
 the nerve centres situated in the floor of the fourth ventricle. 
 
 1 4-26 36. 
 
THE PONS VAROLII. 
 
 43 
 
 Upon each side of the posterior margin of the raphe, upon 
 the floor of the fourth veutricle, and that of the iter, are two 
 rounded cords, the fasciculi teretes. These are broad in the 
 ventricle below, narrow above in the floor of the iter, and are 
 continuous in front with the gray matter upon the lateral 
 walls of the third ventricle. These columns attend the pos- 
 terior margin of the raphe as far as the floor of the third 
 ventricle. The superior margin of the raphe curves abruptly 
 in the floor of the third ventricle forward to the base of 
 the brain in front of the corpora albicantia. 
 
 In that part of the raphe which separates the crura cere- 
 bri is an oval opening about the size a split pea, around which 
 the fibres of the raphe separate to form its margins. This 
 opening in the raphe is filled by the extremity of a tract of 
 broken fibres which ai'e those of the decussation of the pro- 
 cesses, or superior peduncles of the cerebellum. The fibres 
 of the processes pass beneath the fasciculi teretes, and 
 decussate within this opening in the raphe. The pro- 
 cessus of the opposite side crosses the raphe at this point to 
 reach the red nucleus which is situated external to the raphe 
 above the point of decussation. (The letters RN Figure 26, 
 are placed over the situation of the red nucleus which is 
 buried within the tegmentum of the cms cerebri.) The 
 opening in the raphe, just described, is above the superior 
 margin of the pons, and in the middle of that portion of the 
 raphe which separates the cruras cerebri from each other. 
 
 By the removal of the raphe there will be seen, behind 
 the pons, the margin of a longitudinal tract of white fibres 
 extending from the medulla oblongata to the crus cerebri 
 above. This tract, is the internal lateral margin of the 
 lemniscus or fillet, Avhich is separated from its fellow by the 
 raphe. This tract is crescent in shape, with its concavity 
 
 downward curve 
 of the upper bor- 
 der ot the raphe 
 in the floor of the 
 
 third 
 
 )val opening il 
 raphe. Fig. 
 (PTJ. 
 
 Red nucleus. Figs. 
 10 13 to 15^-19*- 
 20* (RNJ. 
 
 Internal margin of 
 the lemniscus or 
 fillet. Fig. 26 (FT). 
 
)-postenor 
 ction of the 
 Figs. 11 to 
 
 44 ARCHITECTURE OF THE BRAIN. 
 
 applied to the posterior convexity of the lenticular section 
 of the pons before described. Behind the fillet is a layer 
 of gray matter which underlies the floor of the fourth ventri- 
 cle, and constitutes the fascicula teretes. 
 
 The pons, therefore, consists of two distinct portions ; an 
 anterior portion composed of transverse and longitudinal 
 fibres, the deep layer of which is mixed with gray matter, a 
 section of which is lenticular in shape ; and a posterior por- 
 tion, plano-concave in shape, and composed of two layers, 
 which is the continuation of the spinal cord and medulla 
 oblongata, except the anterior pyramids in front, and the 
 restiform bodies behind. These two portions of the pons 
 Varolii are easily separated from each other by dividing the 
 anterior pyramid and gently tearing the transverse fibres of 
 the pons from those behind which have a longitudinal direc- 
 tion. These portions of the pons are distinct in function, 
 that in front being commissural containing the great com- 
 missure of the cerebellum and the motor tract, and that 
 behind belonging to the sensory tract and the column of gray 
 matter called the fascicula teretes, which is a continuation of 
 the gray column of the spinal cord. 
 
 These parts may be more readily understood by a dissec- 
 tion from before backwards. The anterior division of the pons 
 is composed of two layers, and the posterior division also of 
 two layers, which will be described in succession. The super- 
 ficial layer of the anterior division of the pons has before 
 been described as consisting of three parts, an inferior portion 
 which has a transverse direction, a middle portion which is 
 transverse on each side of the basilar groove and laterally 
 arches downward to overlap the extremities of the inferior 
 fibres, and an upper portion which emerges from the posterior 
 perforated space and passing outwards and backwards around 
 
THE PONS VAROLII. 
 
 45 
 
 the crura cerebri to terminate in the cerebellum along with the 
 restiform bodies. The superficial layer of the pons Varolii 
 is the great transverse commissure of the cerebellum, excej^t- 
 ing its superior fibres, which are the restiform fibres from 
 the floor of the fourth ventricle, as before stated. If this 
 layer of fibi'es, which is the commissural layer, be divided in 
 an anterio-posterior direction, it will be seen to average one 
 sixth of an inch in thickness. Beneath this layer is a netwoi'k 
 of transverse and longitudinal fibres interspersed with gray 
 matter, and is called the formatio reticularis of the pons 
 Varolii. The network is composed of the deep transverse 
 fibres of the middle peduncle of the cerebellum, interlacing 
 with fibres which descend from the crustae of the crura cerebri. 
 The fibres of a crusta are disposed in laminae, similar to 
 those of the internal capsule, and are placed one behind 
 the other in the crus, but as they descend into the pons they 
 are separated from each other in order that the transverse 
 fibres of the deep layer of the pons, also disposed in laminae, 
 may be inserted between those of the crusta as they descend. 
 The vesicular matter of the pons is interspersed throughout 
 this formatio reticularis, but is more concentrated in the middle 
 of the posterior portion of this part of the pons. The gray 
 matter of the pons is called its nucleus, and is continuous 
 above with the locus niger or vesicular tract of the crus 
 cerebri. 
 
 The fibres derived from the anterior pyramids of the 
 medulla oblongata pass upward with the longitudinal fibres 
 of the pons to the crusta and internal capsule. The reticulated 
 layer is the motor portion of the pons Varolii. It consists of 
 the crusta, the fibres of the anterior pyramid, the deep layer 
 of the transverse fibres of the middle peduncle, together with 
 the gray matter, or the ganglion of the pons Varolii. The 
 
 Superficial layer 
 of tlie anterior 
 portion of the 
 pons is the great 
 commissure of 
 cerebellum. Figs 
 9-34-35. 
 
 Deep layer of tin 
 
 5 of the 
 Figs. 34-35. 
 
 10 to 13-33-33. 
 30*-21i'(SN). 
 
46 ARCHITECTURE OF THE BRAIN. 
 
 The ganglion the of 
 pons i^ the exter- 
 nal 1 asal gangli- 
 
 Longitudinal fib 
 of the Vai-oli 
 Figs. 11 to 14. 
 
 ganglion of the pons is the motor basal ganglion of the cere- 
 bellum, and is the analogue of the lenticular ganglion of the 
 cerebrum. 
 
 The posterior division of the pons Varolii, or that portion 
 of it which is a continuation of the spinal cord, can be better 
 studied by the removal of the part which has just been 
 described. If the anterior pyramids and the lateral attach- 
 ments of the pons to the cerebellum are divided, and the anter- 
 ior portion of the pons is gently lifted from its bed, it will sep- 
 arate from a broad band of longitudinal fibres, extending from 
 the medulla oblongata to the crura cerebri. By a division of the 
 crusta above, the whole can be removed in a mass, leaving a 
 broad excavation flat from side to side and concave from above 
 downwards. This surface is divided into lateral halves by an 
 elevated ridge of torn fibres which extends longitudinally 
 from the anterior median fissure of the medulla oblongata to 
 the center of the interpeduncular space above. The central 
 ridge is composed of the ruptured fibres of the raphe. The sur- 
 face exposed presents the appearance of a broad transverse 
 groove, and lodges the anterior portion of the pons Varolii. 
 Upon each side of the anterior median fissure, along the lower 
 pyramids, boi'dcr of the groove, are the divided ends of the anterior 
 Figs. 9- pyiamids which project upwards as the extremities of 
 rounded cords. Upon the outer s'de of these are the upper 
 extremities of the olivary l^odies, external to which are the 
 lateral tracts of the medulla oblongata, and more externally 
 the arched fibres of the restiform bodies. Emerging from 
 beneath the divided extremities of the anterior pyramids, and 
 from between the olivary bodies and the raphe, are two tracts, 
 one on either side, which ascend in an outward direction, 
 obliquely to the upper and outer margins of this surface where 
 they become superficial. They overlap the anterior part of 
 
 ilevated ri 
 
 idge di 
 
 viding th 
 
 e le.n- 
 
 niscus CI 
 
 - fillet 
 
 longitndin 
 
 ally in 
 
 the middli 
 
 5 line. 
 
 See raphe 
 
 . Figs, 
 
 11 to 14. 
 
 
 nedull 
 
Fig. 12, 
 
 Anterior root zc 
 or lateral trac 
 llie medulla. 
 Figs. 7-10-1 1-12 
 
 fourth ventric 
 Figs. 11-12-13. 
 
 THE PONS VAROLII. 47 
 
 the processes and terminate in the testes and brachia pos- 
 terius. These tracts are the continuation of the fundamental 
 root zones of the spinal cord. They have been called the 
 anterior layer of the lemniscus, or fillet, but are distinct tracts 
 of fibres which connect the corpora quadragemina with the 
 anterior horns of the gray matter of the spinal cord, and 
 do not belong to the same system of fibres as the fillet. 
 Beneath the layer just described, is a longitudinal layer of oiivary tasc 
 fibres derived from the olivary bodies of the medulla oblon- 
 gata, and is called the olivary fasciculus. Under the olivary 
 fasciculus is a similar layer which is continuous below with the 
 lateral columns of the medulla oblongata, and the anterior root 
 zones of the spinal cord. Behind this layer is one which is 
 derived from the gray matter of the fasciculi teretes and which 
 joins the fillet above and from the inner side of the restiform 
 body. The three layers last described constitute the fillet 
 proper, but it will be convenient in ordinary to say, that these 
 four layers unite in forming the longitudinal layer of this 
 portion of the pons Varolii. The outer margin of the fillet 
 forms the internal boundary of a triangle, which is bounded 
 above by the processus, and behind by the restiform body, 
 and is called the restiform triangle. ^Fi'»l°9"to'iT"^'^ 
 
 The vesicular layer of the posterior portion of the pons 
 Varolii underlies the floor of the fourth ventricle, and Ijeiog 
 elevated upon its posterior surface is called the fasciculi 
 teretes. This layer is continuous below with the gray col- 
 umns of the spinal cord, which, in the floor of the fourth 
 ventricle, are separated behind, so that the posterior cornua 
 are external upon the sides, and the anterior cornua lie 
 together along the median fissure of the ventricle. On ac- 
 count of this disposition of the anterior and posterior cornua, 
 the centres of the motor nerves of the medulla oblongata are 
 
 Fasciculi tere 
 Figs. 1015. 
 
rhe fourth ventri- 
 cle. Figs. 8-10- 
 15-26. 
 
 48 ARCHITECTURE OF THE BRAIN. 
 
 placed along the median line of the ventricle, and those of 
 the sensory nerves upon its sides. 
 
 The fourth ventricle: — The fourth ventricle is situated 
 behind the pons Varolii and the upper half of the medulla 
 oblongata. It is bounded below, on each side, by the rest- 
 iform bodies, and above by the inferior margins of the pro- 
 Root. Figs. 8-26. cesses. Its roof is formed by the processes on each side, and 
 by the valve of Vieussens in the middle. It is about one inch 
 and a half in length from above downwards, and about three- 
 quarters of an inch in width at its wadest part, which is be- 
 tween the upper j)ortion of the restiform bodies, its depth from 
 above downwards, from the valve of Vieussens to the median 
 fissure, is about five-eighths of an inch. Its floor is lozenge 
 shaped and pointed at either extremity, its upper extremity is 
 continued by the iter to communicate with the third ventricle. 
 Its lower extremity is continuous with the central canal and 
 the posterior median fissure of the spinal cord. The median 
 fissure of the fourth ventricle divides its floor into lateral 
 
 "^ -^- halves, and is the posterior boundary of the raphe. The resti- 
 
 form bodies are elevated on each side above the level of the 
 floor of the ventricle, and their gradual approach and junction 
 at the lower extremity of the ventricle resembles a pen in 
 appearance, hence the lower extremity of the ventricle is 
 1ut!"''Figs.Tia called the calamus scriptorius. 
 
 Below are two slight elevations or grey tubercles, one 
 upon each side of the apex of the ventricle, the clavate 
 
 F^^Ts-'ir''"' nucleii, which are the terminations of the posterior pyra- 
 mids of the medulla oblongata. Directed upwards and 
 outwards from these tubercles, along the floor of the fourth 
 ventricle internal to the restiform body on either side, is a 
 
 )rigjn of tlie deep '' ' 
 
 layer of the fillet ti'act of whitc fibrcs wWch passes through the restiform trian- 
 
 in the fourth ven- ■*■ ° 
 
 tricie. Figs. 8-10 g]g^ ^q jq^q the fillct. Thls ti'act forms the posterior Layer of 
 
 tricle. Figs. 8-10- 
 
THE PONS VAROLII. 
 
 49 
 
 the fillet, and a portion of it turns outward with the restiform 
 body to the cerebellum. It also receives the anterior root of 
 the eighth nerve as this root turns downward from the resti- 
 form triangle into the fourth ventricle to reach the auditory 
 nucleus, which is situated beneath the floor of the ventricle at 
 the side of calamus scriptorius. 
 
 At the lower part of the restiform body, external to the 
 ventricle, and above the clavate nucleii, is a broad elevation 
 covered by white fibres which marks the situation of the 
 restiform nucleus. The restiform nucleus is the superior ter- 
 mination of the posterior column of the medulla oblongata 
 and spinal cord, and it is the origin of a large portion of the 
 fibres which constitute the restiform body. 
 
 The floor of the fourth ventricle is gray in color, some 
 parts of it presenting bluish elevations which are the centres 
 of nerves, and are called loci cerulii. If the sides of its me- 
 dian fissure are separated, the torn surfaces present a striated 
 appearance of antero-posterior oblique fibres, which inter- 
 mingle across the median line. The fibres thus separated 
 compose the raphe before described. 
 
 Crossing the surface of the floor of the fourth ventricle, 
 about its middle, are several stride, which are the striae trans- 
 transvers?e. The inferior stride are derived externally from 
 the posterior root of the eighth nerve (auditory), which pass 
 inward beneath and across the flexion of the restiform body to 
 the floor of the fourth ventricle, to enter the raphe, in the me- 
 dian line, among the fibres of which they are lost. The superior 
 striae transversie commence above the arch of the restiform 
 bodies upon the outer margin of the floor of the ventricle, 
 and are directed downward and inward, obliquely from the 
 restiform triangle to the raphe. 
 
 eiKl.th ner 
 Figs. 8-9. 
 
 Restifor: 
 Figs. 8 
 
 jtnas transversae. 
 Figs. 8-10. 
 
 Posterior root of 
 auditory nerve. 
 Figs. 8-10. 
 
 Root of tlie facial 
 
50 
 
 ARCHITECTURE OF THE BRAIN. 
 
 lavity of the fourth 
 ventricle. Figs. 
 8-10-26-25* to 29*. 
 
 They may be traced as far forward, and below, as 
 the inferior margin of the pons Varolii, at the anterior me- 
 dian fissure of the medulla. These fibres are continuous out- 
 wardly on the same side with the seventh nerve (facial), and, 
 internally, at the anterior median fissure, with the anterior 
 pyramid of the opposite side. 
 
 The roof of the fourth ventricle is arched from side to side, 
 and diminishing in size gradually towards its anterior extrem- 
 ity encloses a conical shaped cavitiy which is contracted 
 above to be continuous with the iter. This cavity lodges 
 the inferior vermiform process of the middle lobe of the 
 cerebellum, the superior vermiform process resting upon the 
 upper surface of the parts forming the roof of the fourth 
 ventricle. 
 
 The parts which form the roof the fourth ventricle, viz. : 
 the processes and the valve of Vieussens, which enter the 
 upper part of the hilus of the cerebellum are connected behind 
 with the dentate body. In front they assist in the formation 
 of the peduncles of the cerebrum. 
 
 To recapitulate: The pons Varolii is divided into two por- 
 tions, an anterior or cerebellar, and a posterior or spinal. 
 These portions include from before backwards: first, a trans- 
 verse layer which is the commissure of the cerebellum; second, 
 a reticulated and vesicular layer, which is the motor tract ; 
 third, a longitudinal layer, the lemniscus or fillet; fourth, a 
 vescicular layer or the fasciculi teretes ; and fifth, the resti- 
 form bodies or inferior peduncles of the cerebellum, which 
 will be described with the medulla oblongata in connection 
 with the tracts from which they are derived. The relation of 
 these layers to each other should be recollected, in order to tra,ce 
 their distribution above in the formation of the crus cerebri 
 and internal capsule, as well as their connections below with 
 the medulla oblongata and spinal cord. 
 
THE MEDULLA OBLONGATA AND SPINAL CORD. 
 
 These parts of the cerebro spinal axis are so intimately 
 associated in general structure, and in the contitiuity of the Medunaands inai 
 tracts of grey and white columns of which they are consti- cord. Figs. -to in. 
 tuted, that it will be convenient to describe them together. 
 The medulla oblongata is properly the upper portion of the 
 spinal cord, in which there is a rearrangement of its columns 
 and tlie addition of important nerve centers. The spinal cord 
 possesses the distinction, that in its structure the vesicular or 
 grey matter is enclosed within the white matter, while in that 
 of the brain the gray matter is external. 
 
 The cord including the medulla is about eighteen inches 
 in length, extending from the lower border of the pons 
 Varolii downward in the spinal canal to about the level of the 
 lower border of the first lumbar vertebra. It terminates in 
 a slender filament, the filum terminale, which contains a small 
 amount of gray matter and ends at the sacral canal. 
 
 The spinal cord is rounded in transverse section, is divided xransve 
 
 Figs, t 
 
 into lateral halves by an anterior and posterior median fissure, 
 the former extending upward to the lower border of the pons 
 Varolii, and the latter to the separation of the posterior col- 
 umns of the cord which form the sides of the fourth ventri- 
 cle. About an inch and a half below the inferior border of 
 the pons the anterior median fissure is partially obstructed by 
 a tract of decussating fibres, which are those of the anterior 
 pyramids of the medulla oblongata. The lower extremity 
 of the decussation of the pyramids is the line of division Ta""^' 
 
Ves: 
 
 52 ARCHITECTURE OF THE BRAIN. 
 
 between the spinal cord proper wliich is the lower portion, 
 and the medulla oblongata above. At the point of decussa- 
 tion there is an interruption in the grey elements of the spinal 
 cord, produced by tracts of white fibres, which are directed 
 forward from the deep fibres of the lateral columns of 
 the cord, to become superficial in front of the medulla 
 oblongata. The lateral halves of the cord are united in the 
 middle by a commissure, which is white in front and grey 
 behind. In the middle of the grey commissure is a minute 
 canal, the ventricle of the spinal cord, which extends through 
 its length and opens into the fourth ventricle at the 
 apex of the calamus scriptorius. The fourth ventricle is 
 a conthauation of the centrtd canal of the spinal cord, and is 
 formed by a defect of the posterior commissure of the cord 
 and a separation of its posterior colunms into the resti- 
 form bodies. The fourth ventricle begins in the middle of 
 the posterior surface of the medulla oblongata. 
 
 The grey substance of the spinal cord is arranged in two 
 columns, one on each side, united by a grey commissure 
 which contains the central canal. The anterior portion 
 nT of each column is called its anterior horn and is the motor 
 vesicular column of the cord ; the posterior projection or 
 column of grey matter is called the posterior grey horn, 
 or sensory arm. At the junction of the posterior cornu 
 with the grey commissure is a slender vesicular column, 
 of Clarke. Fig. callcd the vesicular column of Clarke. This column is prob- 
 ably the cerebellar element of the spiaal cord, since it is 
 connected directly with the cerebellum by the direct cere- 
 bellar tract, and degenerates along with it in the disease 
 known as cerebello spinal ataxia. 
 
 The anterior vesicular columns of the spinal cord are dis- 
 turbed or interrupted by the decussation of the anterior pyra- 
 
 Fig. 
 
THK MEDULLA OBLONGATA AND SPINAL CORD. 53 
 
 mids of the medulla about au inch and a half below the 
 pons Varolii. As the vesicular columns of the cord apj^roach 
 the fourth ventricle the posterior cornua, or posterior vesicu- 
 lar columns, gradually diverge, and the anterior cornua ap- 
 proach each other toward the median line. In the floor of 
 the fourth ventricle the grey columns are spread into a grey 
 sheet, which forms the fasciculi teretes of the floor of the 
 ventricle; the anterior columns lying along the median fissure, 
 and the posterior along the sides of the floor of the ventricle. 
 The sensory roots of the spinal nerves terminate in the 
 posterior vesicular columns of the spinal cord, and the sen- 
 sory cranial nerves in masses of vesicular matter in the outer 
 part of the floor of the fourth ventricle. The motor roots 
 
 Connections c 
 
 of the spinal nerves are connected with the anterior vesiclar spinainervei 
 
 the grey hoi-: 
 
 columns of the cord, and the motor cranial nerves with the F's- sb. 
 motor centers along the middle of the floor of the ventricle. 
 The roots of the spinal nerves emerge from the sides of 
 the spinal cord; the anterior roots in a line about one-third of 
 the distance laterally on each side of the anterior median 
 fissure, and the posterior roots also about one-third of the 
 distance outward upon each side of the posterior median fis- 
 sure, dividing the spinal cord on each side into three columns, 
 anterior, lateral and posterior. Each column of the cord 
 is subdivided into tracts which can be traced through '=°'";!™ 
 
 o cord. 
 
 the medulla to join with the several divisions of the pons 
 Varolii described, and with the restiform bodies or inferior 
 peduncles of the cerebellum. 
 
 The spinal cord is variable in size in diff'erent localities, 
 due to the dift'erence in the volume of the spinal nerves oescripti 
 received by it at certain points. The lumbar enlargement is 
 near the lower end of the cord and receives the nerves from 
 the lower extremities. The cervical enlargement extends 
 
 Anterior, lateral 
 and posterior 
 
 t tlif 
 1 cord. 
 
64 ARCHITECTURE OF THE BRAEST. 
 
 from the third cervical to the first dorsal vertebra, receives 
 the nerves from the upper extremity and is somewhat larger 
 than that of the lumbar region. The medulla oblongata is 
 the uppermost enlargement of the spinal cord, it lies within the 
 cranial cavity and is sometimes called the bulb. This part of 
 the spinal cord contains the centers which control the func- 
 tions of respiration and circulation, and is therefore one limb 
 of the tripod which immediately sustains life. It also co- 
 ordinates the muscles that perform the acts of deglutition 
 and speech, besides other important functions. Symptoms 
 indicating defection of this part of the central nervous sys- 
 tem are of grave import, and are spoken of as bulbar symp- 
 toms, bulbar paralysis, etc. Certain diseases originate from 
 functional or organic disturbance of the medulla, therefore a 
 familiarity with its anatomy is fundamental to the diagnosis 
 of these diseases, and also assists in the eaidy recognition of 
 those symptoms which denote the approach of death. The rela- 
 tions of its tracts to the several nerves of distinct function 
 provide ceitain combinations of symptoms by which the anato- 
 mist can determine the exact situation and extent of a lesion. 
 
 In order that the relations and the continuity of the col- 
 umns and tracts of the spinal cord with those of the medulla 
 oblongata, and the tracts of the latter with the divisions of 
 the pons Varolii and with the cerebellum, may be more 
 clearly understood, we will locate and name, first, the tracts 
 of the spinal cord, then those of the medulla, and afterward 
 associate them with each other, and with the divisions of the 
 pons which have before been described. 
 
 The spinal cord proper, as stated, is that which extends 
 below the decussation of the anterior pyramids of the me- 
 dulla oblongata. It is uniform in structure, size and appear- 
 ance except the enlargements of its cervical and lumbar 
 
15-38. 
 
 THE MEDULLA OBLONGATA AND SPINAL CORD. 55 
 
 regions, and that its fascicular tracts, or the white substance 
 diminishes in quantity from above downward. 
 
 The grey columns and the central canal, or ventricle of 
 the cord, have been described ; the former as being continu- 
 ous with the grey matter in the floor of the fourth ventricle, 
 and the latter as a part of the ventricular system which 
 extends through the whole length of the cerebro spinal axis. 
 
 It remains to trace the tracts which form the white col- ^ , , . , 
 
 Tracts or the spinal 
 
 umns of the cord and to describe their relations. '^T.t ^"^^' 
 
 The relation of these tracts will be more easily under- 
 stood by an examination of a transverse section of the spinal 
 cord as represented in figure 38, which exhibits the division 
 of the cord into three columns by the anterior and posterior 
 roots of the spinal nerves. 
 
 Each of the three columns of the cord are divided into 
 tracts, the anterior and the posterior each, into two, and 
 the lateral into four. Each of these tracts are endowed 
 with a specific function, and are arranged in bundles which 
 can be se2:)arated in part by careful dissection, traced by 
 the degeneration observed as the result of disease, and also 
 by the observation of the development of the embryo. 
 
 Upon either side of the anterior median fissure is a small 
 column which descends directly from theanterior pyramid of dsi 
 the medulla, called the direct pyramidal tract, or column of i 
 Tiirck. The remaining portion of the anterior column of 
 the cord, which is much the larger part, is called the funda- 
 mental root zone, because it is among the first elements to de- " 
 velope in the spinal cord. 
 
 Oq either side of the posterior median fissure is another 
 small column, called the posterior median column, or col- 
 umn of Gall, which is supposed to be the respiratory tract of °> 
 the cord. The remaining portion of the posterior column of the 
 
56 
 
 ARCHITECTT'EE OF THE BRAIN. 
 
 Posterior root zone 
 or column of Bur 
 dach. 
 
 Crossed pyr 
 tract. 
 
 Crosses the media 
 line to join th 
 anterior pyrami 
 of the opposil 
 side. Fig. 14. 
 
 cord, which is much Lirger than the preceding, is called the 
 posterior root zone, the cuneate fasciculus, or the column ( f 
 Burdach. It is the sensory column of the spinal cord, dis- 
 ease of which disorders muscular coordination, as in the 
 case of progressive locomotor ataxia. 
 
 The lateral column of the spinal cord is constituted of 
 four fasciculi or tracts, and is included between the lines of 
 emergence of the anterior and posterior roots of the spinal 
 nerves. These tracts are: first — a ribbon like tract situated 
 directly in front of the extremity of the posterior horn of 
 grey matter of either side, and occupying the surface of the 
 lateral column for about half its extent. This tract is con- 
 nected in the spinal cord with the grey column of Clarke, and 
 is continued above upon the lateral surface of the medulla 
 and restiform body to the cerebellum. It suffers degenera- 
 tion in the disease known as cerebello spinal ataxia, which 
 runs a rapid course, affecting principally the nutritive func- 
 tions of the body. Second — beneath the direct cerebellar 
 ti'act, and anterior to the posterior horn of the grey matter, is 
 a rounded fasciculus called the crossed pyramidal tract. This 
 tract is connected with the vesicular matter of the posterior 
 horn of the cord, and above with the anterior pyramid of the 
 opposite side of the medulla oblongata. It decussates with 
 the crossed pyramidal tract of the opposite half of the spinal 
 cord in the anterior median fissure, at the lower extremity of 
 the medulla. Beyond the decussation it unites with the 
 opposite direct pyramidal tract to form the anterior pyramid 
 of the opposite side of the medulla. The crossed pyramidal 
 tract is the motor column of the cord, and possibly the offioe 
 of the direct pyramidal tract is to co-ordinate the muscles of 
 one side of tlie body with those of the other. Third — 
 between the columns just described, and the anterior cornu 
 
THE MEDULLA 015L0NGATA AND SPINAL CORD. 
 
 57 
 
 of grey matter and the anterior roots of the spinal nerves, 
 is a large column of fibres forming the anterior portion 
 of the lateral column of the cord. It is called the anterior 
 root zone, and in the spinal cord is supposed to contain 
 longitudinal fibres that connect the segments of the cord 
 together, and also a sensory tract (Gowers) which is continued 
 into the cerebrum. This tract is nearly uniform through- 
 out the spinal cord, and is continued upon the side of 
 the medulla to join the fillet. Fourth — internal to the 
 three tracts just described and lying next to the concave 
 outer surface of the grey column of the cord, is a reticulated 
 column composed of the interlacing fibres of the other fas- 
 ciculi of the lateral column of the spinal cord. This tract is 
 the formatio reticularis of the cord, and corresponds to the 
 corona radiata of the cerebrum and cerebellum. It is also 
 called the mixed lateral column, and is not properly a distinct 
 fasciculus of the spinal cord. 
 
 The MEDULLA OBLONGATA. — The lower portion of tlie me- 
 dulla corresponds to the spinal cord in size, shape, and in the 
 arrangement of its columns, with the exception, that the 
 crossed pyramidal tracts of the lateral columns of the cord, 
 pass forward, decussate with each other, and join the 
 direct pyi'amidal tracts of the anterior columns, to form the 
 anterior pyramids of the medulla. The posterior median 
 columns of the cord are called, in this situation, the posterior 
 pyramids of the medulla, and terminate above in the clavate 
 nucleii at the apex of the fourth ventricle. The posterior 
 column of the cord (Burdach's) occupies the same relative 
 position in the medulla as in the spinal cord, and terminates 
 above in the restiform nucleus, which is situated in the resti- 
 form body above and external to the clavate nucleus. The 
 direct cerebellar tract is continued upward, on the surface of 
 
 Posterior pyran 
 Figs. 8-10-15. 
 
 stitorin 
 s. Figs. 
 
58 
 
 AECHITECTUEE OF THE BRAIN. 
 
 Anterior i 
 or latera 
 medulla 
 10 to I-l. 
 
 Fundamental root 
 zone. Figs. 9-11 
 to U-36. 
 
 Relation of the 
 tracts which from 
 the lower part of 
 the medulla. 
 Figs. 7-9 10-36. 
 
 Upper portion t 
 the medulla. 
 Figs. 9-10-36. 
 
 Section 
 of the 
 Fig. 36. 
 
 nd raphe 
 medulla. 
 
 the medulla and the restiform body, to the cerebellum. This 
 tract covers the restiform nucleus so that the latter is not 
 exposed upon the surface. The anterior root zone, or lateral 
 tract of the medulla, passes upward upon the side of the me- 
 dulla to the lower extremity of the olive where it becomes 
 compressed, between the latter and the restiform body, into a 
 narrow tract which above forms the middle layer of the fillet 
 of the pons. The fundamental root zone above the cord is 
 crowded outward by the anterior pyramid, as far as the lower 
 extremity of the olive. Just below this point, it is flattened 
 in front to accommodate the decussation of the pyramids and 
 disappears from the surface of the medulla to get behind the 
 pyramid between the olive and the raphe, in which situa- 
 tion this tract is prismatic in shape, its sides being in relation 
 to the parts just mentioned. Above the olive, it escapes to 
 form a flat layer of fibres upon the fillet, and terminates above 
 in the testes and brachium posterius. 
 
 The tracts on either side of the medulla oblongata which 
 form its lower part from before backward are: the anterior 
 pyramid, the fundamental root zone, the anterior root zone or 
 lateral tract, the direct cerebellar tract, the posterior column, 
 and the posterior pyramid. 
 
 The upper part of the medulla is attached to the pons 
 Varolii, and is connected with the cerebellum by the restiform 
 bodies, or inferior peduncles of the cerebellum. The medulla 
 gradually enlarges as it ascends from the cord; its upper 
 extremity is about three-quarters of an inch from side 
 to side, and about flve-eighths of an inch from before back- 
 ward. The lower portion of the fourth ventricle is behind 
 the upper half of the medulla oblongata, and the raphe ex- 
 teuding from the median fissure of the ventricle forward to 
 the anterior median fissure of the medulla, divides it into 
 
THE MEDULLA OBLONGATA AND SPINAL CORD. 
 
 59 
 
 lateral halves. A transverse section of the medulla, seen in 
 figure 36, or better in a section one-eighth of an inch above it, 
 is somewhat triangular in shape, with truncated angles, and 
 shows the relation of the tracts which are continued upwards 
 from its lower portion. The relations of these tracts are on 
 either side, beginning from the anterior median fissure and 
 raphe in front: the anterior pyramid; the olivary body, or 
 olive; a triangular tract between the olive and raphe, beneath 
 the pyramid, called the fundamental root zone; the lateral 
 tract, or anterior root zone, compressed between the olive and 
 restiform body; and the restiform body or inferior peduncle 
 of the cerebellum within which is seen the restiform nucleus. 
 Figure 36. 
 
 The parts of the medulla which have not been described 
 are the anterior pyramids, the olive, and the restiform body. 
 The arciform fibres and the fibres from the raphe will be 
 described incidentally with the others above mentioned. 
 
 The anterior pyramids of the medulla emerge from the 
 middle of the lower border of the pons Varolii as two 
 rounded cords, one on each side of the anterior median fissure 
 and raphe of the medulla oblongata. They descend s'de by 
 side, separated by the anterior median fissure, to the point of 
 decussation at the lower extremity of the medulla where each 
 divides into two portions: first, a small tract which continues 
 on the same side of the anterior median fissure of the spinal 
 cord, and is the anterior median column, or column of Tiirck; 
 and, a large tract which breaks up into several bundles of 
 fibres that pass backward and outward, interrupting the an- 
 terior horns of the grey columns of the cord, and reaching 
 the anterior surface of the posterior horns, forms the crossed 
 pyramidal tract of the opposite side of the spinal cord. 
 
 eduUa 
 rto 15 
 
 Anterior pyramids 
 
 Crossed pyramidal 
 tract. Figs. ]4- 
 
60 
 
 ARCHITECTURE OF THE BRAIN. 
 
 Roots o£ tlie 
 seventh nerv 
 Figs. 8-9-10. 
 
 Roots of tlie hypo- 
 between the olive 
 and pyramid. 
 
 Olivary body. 
 Figs. 9 to 14. 
 
 Dlivary fasci( 
 Fig. 12. 
 
 Near the lower extremity of the olive, the pyramid gives 
 off from its outer side a small tract of fibres, which arch be- 
 neath the olive and across the surface of the medulla to the 
 restiform body. These fibres join the restiform body, pass 
 to the cerebellum, and are called the arciform fibres of the 
 medulla. They are probably associated fibres, and do not 
 belong to the pyramidal system which is motor in function. 
 Immediately beneath the pons, fibres are given off from the 
 inner side of the pyramid which enter the raphe to decus- 
 sate with those from the opposite pyramid, and are continu- 
 ous on the floor of the fourth ventricle with the roots of the 
 seventh nerve, or its nucleus of the opposite side. Below the 
 olive other fibres enter the raphe to reach the opposite 
 twelfth nerve, or the hypoglossal nucleus. 
 
 The anterior pyramid is bounded above externally by the 
 olive, from which it is separated, beneath the pons, by a sulcus, 
 and lower down by a slight groove. The lower portion of 
 the pyramid is in relation externally with the fundamental 
 root zone. This zone above is buried beneath the pyramid, 
 between the olive and raphe. 
 
 The olive is an oblong body situated on either side 
 of the medulla, between the pyramid and the lateral tract, or 
 anterior root zone. It is immediately beneath the pons, from 
 which it is separated by a slight groove. This body is about 
 half an inch in length from above downward, and one-fourth 
 of an inch across its middle. Its upper extremity is con- 
 nected with a large tract of white fibres which go to form the 
 anterior layer of the fillet proper, and is called the olivary 
 fasciculus of the fillet. The olivary fasciculus is related in 
 front with the fasciculus of the fundamental root zone, and 
 behind with that derived from the lateral tract of the medulla, 
 or anterior root zone of the cord. The olive is covered 
 
hilus 
 
 connections w 
 the tenth and 
 twelfth nerves 
 
 THK MEDI'LLA OBLONGATA AND SPINAL CORD. 61 
 
 externally by a tliiu layer of transverse striie, derived from 
 the raphe, which passes to the restiform body and to join 
 the commissure of the flocculus. These are probably cere- 
 bellar fibres from the nuclei in the floor of the fourth ventri- 
 cle, belonging to the same system as the uppermost fibres of 
 the pons Varolii. 
 
 A transverse section of the olive (figure 36) shows that it section of th 
 is composed of an external white capsule, within which is a 
 convoluted layer of grey matter surrounding a mass of white 
 subtance. From its hilus, which is above and internal to the ^'s 
 mass, fibres emerge which form a commissure between the 
 opposite olivary bodies, and others are directed backward to 
 the floor of the fourth ventricle to connect with the nuclei 
 of the pneumogastric and hypoglossal nerves. The upper 
 part of the olive with the former, and the lower part with 
 the latter (Van der Kolk). This body is supposed to be 
 concerned with the co-ordination of the muscles of speech. 
 
 The restiform bodies, or inferior peduncles, connect the 
 cerebellum with the medulla and spinal cord. They arise 
 from the posterior and outer angles of the medulla upon the 
 sides of the fourth ventricle, and arch upward and backward 
 between the superior and middle peduncles of the cerebellum, 
 to spread over the upper surface of the corpora dentata, iu 
 which they terminate. The upper border of the restiform 
 body forms the posterior side of the restiform triangle, ami 
 is in relation to the parts transmitted by the triangle, viz : 
 the anterior root of the eighth nerve, the seventh and fifth 
 nerves, and the posterior layer of the fillet. Its posterior 
 border is in relation Avith the posterior root of the eighth 
 nerve and the commissure of the flocculus. A transverse 
 section through the restiform nucleus (figure 36) shows a body 
 
 Restiform bod 
 
 Restiforn 
 and pa 
 
62 ARCHITECTUEK OF THE BRAIN. 
 
 similar but larger than the nucleus of the olive, and that 
 commissural fibres connect the opposite nuclei. 
 Restiform system The Tcstiform system of fibres of either side is derived : 
 
 oE fibres. Figs 
 
 9-10. from the restiform nucleus at the side of the lower extremity 
 
 of the fourth ventricle, from the clavate nucleus, the direct 
 cerebellar tract of the cord, the arciform fibres of the an- 
 terior pyramid, the cerebellar fibres from the floor of tlie 
 fourth ventricle derived from the raphe, and from the upper- 
 most fibres of the pons Varolii, which proceed from the raphe 
 and floor of the fourth ventricle. 
 
RECAPITULATION OF THE TRACTS OF THE 
 CEREBRO SPINAL AXIS. 
 
 In the foregoing pages we have studied the several parts 
 of the cerebro-spinal axis in segments, and have connected 
 each by its immediate relations, and by the continuity of 
 the tracts of which it is composed. 
 
 It will now be of advantage to review the axis as a whole, 
 and to trace its tracts in continuity through its entire extent, 
 in connection with the nerve centers with which they are 
 associated. In so doing, we will attempt to arrange the 
 several tracts and nerve centers into general systems, to accord 
 with their supposed functions, in order to assist the memory 
 in retaining a knowledge of the anatomy, and to simplify 
 what at first sight appears difficult to the student. 
 
 Beginning, therefore, with the spinal cord, we will follow 
 each system from its origin below to its destination above. 
 
 The ventricular system begins as a minute canal, extend- 
 ing through the length of the spinal cord and terminating 
 above in the fourth ventricle, at the middle of the posterior 
 surface of the medulla oblongata. The fourth ventricle is a 
 broad cavity, situated behind the upper half of the medulla 
 and the pons Varolii. At its upper extremity the fourth ven- 
 tricle is contracted into a small canal, the iter, or aquaduct of 
 Sylvius. The iter is about three-fourths of an inch in length, 
 lies beneath the upper extremity of the valve of Vieussens, the 
 commissure of the corpora quadrigemina, and the jiosterior 
 commissure of the third ventricle. The iter terminates above 
 
64 
 
 ARCHITECTURE OF THE BRAIN. 
 
 sure of Bichat 
 nd foramina of 
 
 Lateral ventricles 
 
 Fifth ventricle 
 
 Infundibulum and 
 
 c: 
 
 ivity in the 
 
 P 
 
 ituitary body. 
 
 Co I 
 
 nmunications 
 
 w 
 
 ith tbe sub- 
 
 a 
 
 tachnoid 
 
 in the third ventricle. The third ventricle is a vertical cavity 
 between the thalami optici, extending from the base of the 
 brain to the fornix above, and laterally, upon each side, to the 
 edges of the fornix where it communicates with the lateral 
 ventricles through the fissure of Bichat and the foramina of 
 Monro. The lateral ventricles are large cavities in the hem- 
 ispheres of the cerebrum, and each ventricle sends projections 
 into the frontal, temporal, and occipital lobes, called the an- 
 terior, middle and posterior cornua of the lateral ventricles. 
 The fifth ventricle is enclosed by the two layers of the sep- 
 tum lucidum, and has no communication with the other cavi- 
 ties of the brain. The floor of the third ventricle is con- 
 nected with a cavity in the pituitary body by a canal through 
 the infundibulum. 
 
 The ventricular system communicates with the subarach- 
 noid spaces along the great transverse fissure, and by a 
 foramen in the pia mater above the calamus scriptorius, 
 called the foramen of Majendie. 
 
 The ganglionic system: The grey. matter of the spinal 
 cord is disposed in two columns, one on each side, enclosed 
 by the white matter of the cord. These columns are united 
 by a grey commissure, which contains in its middle the cen- 
 tral canal of the cord, and they are projected forward and 
 backward into cornua, which are the origins of the roots 
 of the spinal nerves. The anterior horns of grey mat- 
 ter are motor in function, and the posterior horns contain the 
 centers of the sensory roots of the spinal nerves. The sens- 
 ory roots are associated with the sympathetic nervous system 
 by ganglia, near their insertion into the spinal cord. The 
 vesicular columns of Clarke extend along the junction of the 
 posterior cornua and the posterior surface of the grey com- 
 missure, one on each side ot the posterior median fissure of 
 
RECAPITULAriON OF THE TRiiCTS OF THE CERERRO RPTNAL AXIS. 65 
 
 the cord. The anterior horns of the grej- matter are inter- 
 rupted at the upper extremity of the spinal cord by the 
 decussation of the crossed pyramidal tracts, and above the 
 decussation they gradually approach the median line of the 
 medulla, while the posterior horns gradually diverge or are 
 turned outward. 
 
 In the fourth ventricle the grey columns are exposed upon 
 its floor to form the fasciculi teretes; the motor nerve centers 
 being disposed internally along the sides of the median fis- 
 sure, and the sensory centers upon the outer sides of the ven- 
 tricle. The grey matter above the fourth ventricle encloses 
 the iter, and contains the centers that control the movements 
 of the eyes. Above the iter, it spreads upon the sides and 
 the floor of the third ventricle; and the sides of the ventricle 
 are united in the center by the grey or middle commissure of 
 the third ventricle. On the floor of the ventricle the grey 
 matter is continuous with the tuber cinereum, infundibulum, 
 and pituitary body, and in front with the lamina cinerea and 
 grey matter of the hemispheres. 
 
 The greater ganglia of the cerebro-spinal axis are : the 
 hemispherical, and the external and internal basal ganglia, of 
 the cerebrum ; the hemispherical ganglia, the corpora dentata 
 and the ganglia of the pons Varolii, or the internal and 
 external basal ganglia, of the cerebellum. 
 
 The lesser ganglia are : the olivary bodies, restiform and 
 clavate nuclei, of the medulla oblongata ; the locus niger, cor- 
 pora quadrigemina, pineal body, the geniculate bodies, the 
 corpora albicautia, and the red nuclei, in and about the crura 
 cerebri. 
 
 Other cerebral ganglia are: the claustrum, and the substan- 
 tia perforata. The olfactory bulbs, though situated in the 
 cranial cavity, may properly be classed with the spinal ganglia. 
 
 Fasciculi teretes. 
 
 Greater ganglia. 
 
 Claustrum. sub- 
 stantia perfor 
 
White substance 
 the spinal cord 
 
 66 ARCHITECTUltE OF THE BRAIN. 
 
 Of the wliite substance of the spinal cord, the fasciculi 
 of which it is composed are rearranged as they j)ass upward 
 through the several portions of the central nervous system, 
 and are associated with the grey masses above mentioned. The 
 direct pyramidal tract, and the crossed pyramidal tract of the 
 opposite side of the spinal cord, unite to form the anterior 
 pyramid of the medulla oblongata. The anterior pyramid 
 enters the pons Varolii and is associated with the reticulated 
 layer of the anterior portion of that body. This layer of 
 the pons has been described as being connected above with 
 the crusta of the crura cerebri, and laterally with the deep 
 layer of the middle peduncles of the cerebellum. It also con- 
 tains a large amount of vesicular matter, and is the ganglion 
 of the pons Varolii. The crusta is the continuation of the 
 pyramidal tract above the pons, much enlarged by an accession 
 of fibres from this body, and is distributed to the lenticular 
 nucleus, and through the internal capsule, to that part of the 
 hemispherical ganglion situated about the fissure of Rolando, 
 which is the motor area of the hemisphere. The fibres de- 
 rived from the crusta occupy the middle portion of the inter- 
 nal capsule. The entire tract with its associations, just 
 described, constitute the motor system of the cerebro-spinal 
 axis. 
 
 The fundamental root zone lies upon the outer side of the 
 direct pyramidal tract in the cord, and in the medulla as far 
 as the lower extremity of the olive, where it passes inwards 
 beneath the the anterior pyramid between the olive and 
 the raphe. Above the olive, it spreads out into a thin layer 
 of fibres which crosses the fillet obliquely in an outward 
 direction to the upper border of the middle peduncle of the 
 cerebellum, where it becomes superficial upon the anterior 
 part of the outer surface of the superior peduncle, or pro- 
 
RECAPITULATION OF THE TEA0T9 OF THE CEREBRO SPINAL AXIS. 67 
 
 cessus, and terminates in the testes and brachium posterius. 
 These tracts, one on each side, might with propriety be called 
 the posterior peduncles of the corpora quadrigemina, and it 
 is probable that through them, movements of the body, and 
 the maintenance of the equilibrium, are directed by vision. 
 Possibly it is the function of the nates to direct the move- 
 ments of the eyes to accommodate the vision to the attitudes 
 of the body and the movements of an object, and of the 
 testes to regulate the actions of the muscles to avoid a blow 
 or to grasp an object. 
 
 The fundamental root zones, the corpora quadrigemina, 
 brachia, corpora geniculata, the grey matter around the iter 
 and the optic tracts together constitute a visual reflex system. 
 
 The anterior root zone, on either side, is divided from the 
 fundamental root zone by the anterior roots of the spinal 
 nerves. It joins the fillet of the pons, in which it lies between 
 the olivary fasciculus in front, and the fillet fibres derived 
 from the floor of the fourth ventricle, behind. In the crus 
 cerebri, the fillet is internal to the crusta, from which it is 
 separated by the substantia nigra. In the crus, it is related 
 internally below with the processus of the same side 
 previous to its decussation, and higher up, with the pro- 
 cessus of the opposite side subsequent to its decussation, and, 
 with the red nucleus of the tegmentum. In the internal cap- 
 sule the fillet crosses the internal surface of the motor tract 
 in an oblique direction, beneath the thalamus, and in front, 
 lies in a broad groove on the anterior margin of the internal 
 capsular fibres of the crusta. It terminates with the fillet 
 fibres derived from the thalamus in the frontal lobe of the 
 cerebrum. 
 
 As the fillet passes upward from the pons Varolii it 
 receives accessions from various ganglia, and a great mass from 
 
Cerebello-spinal 
 
 68 ARCHITECTURE OF THE BRAEN. 
 
 the thalamus, which unite with it to form the anterior division 
 ©f the internal capsule. The longitudinal commissures of 
 the cerebrum unite with the fillet in the anterior lobes of the 
 brain, and with it constitute the fillet system. There is evi- 
 dence to support the theory, that the fillet is the perceptive 
 system through which the mind is made acquainted with its 
 environments; and, through the medium of the longtudinal 
 commissures, with the memories of things and the events 
 of the past, which have been laid up in the temporal and 
 occipital lobes of the brain. 
 
 The direct cerebellar tract of the spinal cord originates 
 in the vesicular column of Clarke, occupies the outer side of 
 the cord, medulla and restif orm body, and with the latter passes 
 into the cerebellum. It probably assists in the formation of 
 a cerebello-spinal system, which is concerned in the function 
 of nutrition. 
 
 The posterior median columns are continued in the me- 
 dulla by the posterior pyramids, and terminate in the clavate 
 nuclei, beyond which their connections are uncertain. If 
 these columns are respiratory tracts, as supposed by some au- 
 thorities, they probably form an arc with the fifth and pneumo- 
 gastric nerves, through which the muscles of respiration are 
 co-ordinated and brought into action. Until corrected, we 
 will class this tract and its associations as a respiratory 
 system. 
 
 The posterior root zone, or Burdach's column, lies external 
 to the posterior median column, and behind the posterior 
 horn of the grey matter of the cord and the lower half of the 
 medulla. This column terminates above in the restiform 
 nucleus, and is continued by the restiform body to the dentate 
 nucleus of the cerebellum. It is associated by the corpus 
 
 Organ:c and mem- •' a 
 
 ory system. dcutatum wlth thc cerebellum behind, and above, by the pro- 
 
 Reflex respiratory 
 
EECAPITDLATION OP TAE TAAOTS OF THE CEREBEO SPINAL AXIS. 69 
 
 cessus with the opposite red nucleus, thalamus, and hemis- 
 phere of the cerebrum. The association formed by this tract 
 in conjunction with the cerebellum, and the temporal and 
 occipital lobes of the cerebrum, including the intermediate 
 tracts and grey masses, constitutes the organic and memory 
 system. 
 
 Thus the columns of the spinal cord are associated into 
 six systems, having distinct functions, which are co-ordinated 
 at various points by vesicular masses that unite the several 
 systems into one great function, comprehended in the word 
 mind. 
 
 The reader is here cautioned against accepting, without 
 due reflection and investigation, the theories advanced in rela- 
 tion to the function of the tracts described and associated 
 into systems. This has been done for the purpose of assist- 
 ing the memory in retaining the anatomical relations. 
 
CENTRAL ORIGIN AND RELATION OF THE 
 CRANIAL NERVES. 
 
 First nerve - 
 Olfactory. 
 
 The cranial nerves are twelve in number and are enumer- 
 ated from before backward, as : first, the olfactory, which con- 
 sists of the olfactory bulb, and nerve or commissure, which is 
 lodged in the olfactory fissure upon the orbital surface of the 
 frontal lobe of either hemisphere of the brain, parallel with 
 the anterior median fissure of the cerebrum. The nerve 
 divides behind into three roots, external, middle, and internal. 
 The external root crosses the outer part of the anterior per- 
 forated space to the temporal lobe of the hemisphere, the 
 lower portion of which is supposed to be the cerebral center 
 of taste and smell. The middle root dips into the anterior 
 perforated space, and apparently passes backward to the 
 anterior commissure of the third ventricle. In the mole, 
 an animal in which the sense of smell is highly developed, 
 this root is large and appears to decussate with its fellow in 
 the median line, and passes with the commissure to the tem- 
 poral lobe of the opposite hemisphere. The internal root pas- 
 ses inward behind the anterior extremity of the marginal con- 
 volution and is lost in the median fissure, probably forming, 
 with the internal root of the opposite nerve, the commissure 
 between the olfactory bulbs. The connection of the anterior 
 commissure of the third ventricle with the opposite temporal 
 lobes renders it probable that its function is a commissure be- 
 tween the cerebral centers of smell of the opposite hemi- 
 
CENTRAL ORIGIN AND RELATION OF THE CRANIAL NERVES. 71 
 
 spheres. The central arrangement of the olfactory nerves, if 
 the above is correct, is similar to that of the optic nerves. 
 
 The second, or optic nerves of each side, unite to form second nerve- 
 
 jI ,• • ^ * T * ^ , -, . Optic. Figs, 2- 
 
 the optic commissure, and again divide into the optic tracts. 9-10 to 1-1, u*. 
 Each tract winds upon the external surface of the cerebral 
 peduncle, near the posterior part of which it divides into two 
 tracts which terminate: the inferior, in the internal geniculate 
 body; and the superior, a larger tract, in the external genicu- 
 late body and pulvinar of the thalamus. The divisions of the 
 optic tract are connected with the corpora quadrigimina by 
 the brachia, anterius and posterius. The posterior fibres of 
 the optic commissure are commissural between the cerebral 
 nerve centers, the middle fibres decussate, the anterior fibres 
 are commissural between the retinfe,and the external fibres of 
 each nerve are continued into the tract of the same side. 
 
 The third nerve, motor occuli, arises from the inner side 
 of the crus cerebri near the bottom of the posterior perforated 
 space. It pierces the internal margin of the crusta, and upon 
 entering the tegmentum, its fibres spread into numerous striae 
 as they pass through the anterior extremity of the processus, 
 to their destination in the grey matter beneath the iter. 
 
 The fourth nerve, pathetic, arises from the inner margin 
 of the processus, behind the testes, and is -connected with the 
 grey matter surrounding the iter which lies immediately 
 beneath its apparent origin. 
 
 The fifth nerve, the trigeminus, arises from the center of Fifthnerve- 
 
 Trigeminus. 
 
 the side of the pons Varolii. It transfixes the middle pedun- Figs. 7-9-10-13. 
 cle of the cerebellum as it passes obliquely backward, out- 
 ward, and downward to the inferior angle of the restiform trian- 
 gle, through which it reaches the gi'ey matter beneath the 
 floor of the fourth ventricle. It divides into several slips 
 which are distributed to several grey nuclei as far down as 
 
 Motor occu 
 Figs. 7-9-27 
 
 Pathetic. Figs. 
 
72 
 
 ARCHITECTURE OF THE BRAIN. 
 
 Sixth n 
 Abdu 
 
 Eighth nerv 
 Auditory, 
 to 10. 
 
 the calamus scriptoiius. Its motor root is small, aud at its 
 origin is above and behind its sensory root. 
 
 The bixth nerve, the abducent, lies upon the pons, and, 
 winding beneath the lower margin of this body, passes out- 
 ward above the olive to join the fillet at its outer margin, 
 where it is in relation with the fifth, seventh, and anterior 
 root of the eighth nerves. Above, it leaves the fillet to 
 reach the grey matter in the floor of the iter. 
 
 The seventh nerve, facial, arises below the middle pedun- 
 cle of the cerebellum, internal to the flocculus and the audi- 
 tory nerve, and, passing upward behind the middle peduncle, 
 between the restiform body and the outer margin of the 
 fillet, it enters the fourth ventricle through the anterior angle 
 of the restiform triangle. It crosses the floor of the ventricle 
 obliquely downward and inward to the raphe, where it decus- 
 sates with the opposite nerve and joins the anterior pyramid 
 of the opposite side beneath the lower margin of the pons. 
 In the floor of the fourth ventricle it is connected with the 
 nucleus of the seventh nerve. It forms the superior striae 
 transverse of the floor of the fourth ventricle. 
 
 The eighth nerve, auditory, lies beneath the lower margin 
 of the middle peduncle of the cerebellum, between the 
 seventh nerve and the flocculus. It divides behind into two 
 roots, an anterior and posterior, which embrace the restiform 
 body. The anterior root, in conjunction with tlie seventh 
 nerve, passes through the restiform triangle, occupying its 
 superior angle, to reach the floor of the fourth ventricle, 
 where it joins the posterior tract of the fillet, and passes 
 downward on the inner side of the restiform body, to reach 
 the auditory nucleus. The posterior root passes inward 
 beneath the arch of the restiform body, and across it to the 
 floor of the fourth ventricle, upon which it forms the inferior 
 striae transversse. This root divides into striae, which are lost 
 
CENTRAL OEIGLN AND RELATION OF THK CRANIAL NERVES. 
 
 7S 
 
 in the raphe, and is connected with the arciform fibres, and 
 the commissure of the flocculus. It is probable that the 
 roots of the auditory nerve have the same disposition as 
 those of the olfactory and the optic nerves, and possibly this 
 arrangement is common to the roots of all the sensory nerves. 
 
 The ninth nerve, glosso-pharingeal, lies beneath the floc- 
 culus above the pneumogastric nerve, and passes inward 
 behind the olive to the floor of the fourth ventricle, where it 
 is connected with its nucleus. 
 
 The tenth nerve, or pneumogastric, is beneath the ninth, 
 passes inward behind the olive to the floor of the fourth ven- 
 tricle. Its nuclens is connected with the upper part of the 
 olive by a commissure. 
 
 The eleventh nerve, spinal accessory, arises by slips from 
 the lateral tract of the spinal cord as low as the sixth or 
 seventh cervical vertibrae, and from the side of the medulla, 
 which unite into a trunk that lies behind the flocculus and 
 the pneumogastric nerve. Its deep origin is from the anterior 
 horns of the grey matter of the cord. 
 
 The twelfth nerve, hypoglossal, arises from between the 
 olive and anterior pyramid of the medulla. Its roots pass 
 backward between the olive and the fundamental root zone to 
 the floor of the fourth ventricle. Its nucleus is connected with 
 the lower part of the olive and with the opposite anterior 
 pyramid. 
 
 Eleventh nerve — 
 Spinal accessory.' 
 Fig. 7. 
 
 Twelfth 1 
 Hypoglossal. 
 Fig. 7. 
 
74 ARCHITECTURE OF THE BRAIN. 
 
 Figure 1. The appearance of the upper purface of the 
 cerebrum, and the convolutions and fissures marked upon 
 it. The great longitudinal fissure separates the hemispheres. 
 The convolutions are named, and the fissure of Rolando indi- 
 cated upon the left hemisphere; and the three great functions 
 of the brain are located upon the right. The superior ex- 
 tremities of the calloso-marginal and pareto-occipital fissures 
 are marked at their terminations as they emerge from the 
 longitudinal fissure; the former immediately behind the upper 
 extremity of the fissure of Rolando, corresponding to a point 
 just behind the vertex of the skull; and the latter to 
 a point beneath the superior angle of the occipital bone, 
 and the crown of the head. By reference to figure 26, 
 it will be seen that the parieto-occipital and calloso-mar- 
 ginal fissures form the boundaries of certain lobes upon 
 the inner surface of the hemisphere, the upper borders of these 
 lobes occupy the spaces indicated in this plate upon the mar- 
 gin of the longitudinal fissure. The cuneus is located upon 
 surface of the head, by a space extending along the median 
 line from the occiput to the crown; the quadratus — from the 
 crown almost to the vertex; the paracentral lobule — from the 
 vertex to a point an inch and a half in front of it, and the 
 marginal convolution completes the distance to the nasion. 
 
Figure 1. 
 
76 ARCHITECTUEB OF THE BRAIlSr. 
 
 Figure 2. Base of tlie cerebrum: — divided into two 
 surfaces, orbital and temporo-occipital. The whole surface 
 is divided into lateral halves from before backward by (1) the 
 anterior median fissure, (2) the interpeduncular space, (3) the 
 oval hilus of the cerebrum, (4) the posterior median fissure. 
 Each lateral half has three lobes, the frontal, and the tem- 
 poral, separated by the fissure of Sylvius, and behind, 
 the occipital lobe. On each side of the anterior median fissure 
 are the olfactory fissures, bulbs and nerves. Each nerve ter- 
 minates posteriorly in three roots, external, middle and 
 internal. The space between the temporal lobes contains 
 from before backward: (1) lamina cinerea, obscured by the 
 optic commissure, (2) optic nerves commissure and tracts, (3) 
 the anterior perforated spaces, one on each side of the optic 
 commissure, and leading outward from these spaces are 
 the fissures of Sylvius, (4) enclosed by the optic tracts and 
 the crura cerebri are: the tuber cinereum, infundibulum and 
 pituitary body, corpora albicantia, posterior perforated space, 
 and third nerves. In the hilus of the cerebrum are seen: (1) 
 in the middle line the third ventricle, its anterior, middle and 
 posterior commissures, — the anterior and middle commissures 
 are not visible in the figure, — (2) the pineal body, (3) the 
 splenium and lyra of the corpus callosum. On each side of 
 the middle line is the ruptured end of a crus cerebri or pe- 
 duncle. The outer side of the broken surface of the peduncle 
 shows: (1) the crusta, (2) in front, the fillet, (3) midway, the 
 bed of the red nucleus, behind which are (4) the ruptured 
 fibres of the brachia of the corpora quadrigemina, and (5) 
 the posterior extremity of the thalamus opticus or pulvinar. 
 
 On the margins of the posterior median fissure are (1) 
 the posterior extremity of the gyrus, (2) parieto-occipital fissure, 
 and (3) the lobus lingualis. " 
 
 The convolutions seen on this sui'faee can be read upon 
 the plate. 
 
Figure 2. 
 
78 AKCHITECTUBE OF THE BEAUT. 
 
 Figure 3. The upper portion of the cerebrum is removed 
 to a level with the corpus callosum. This body forms a wide 
 furrow in the middle of the surface exposed, and is concave 
 from side to side. Upon each side of the corpus callosum is a 
 crest extending into the anterior and posterior lobes of each 
 hemisphere, which is the line of decussation of the corpus callo- 
 sum with the internal capsule. Internal to the crest, on each side, 
 is the superior longitudinal commissure, or commissure of the 
 gyrus, connecting the occipital and frontal lobes, represented 
 on the left side of the figure. In the center of the corpus 
 callosum is the raphe, upon each side of which are two 
 longitudinal white lines, the stria3 longitudinales or nerves 
 of Lancisci. The corpus callosum is surrounded by the 
 corona radiata, or white substance, in which are seen numer- 
 ous punctate spots or torn vessels, the puncta vasculosa. 
 The corona is bounded externally by grey matter, the hemis- 
 pherical ganglia, which is divided in front and behind by the 
 anterior and posterior median fissures, at the bottom of which 
 are lateral extensions, called the ventricles of the corpus cal- 
 losum. Behind the posterior margin of the corpus callosum 
 are, the gyrus, and the exposed anterior surface of the cuneus. 
 On the lateral margins of the hemispheres are the posterior 
 extremities of the fissures of Sylvius, and a triangle is drawn 
 upon the right side of the figure to illustrate the inter- 
 nuncial fibres, and the external longitudinal commissure ; the 
 former connecting the centers of word and sight mem- 
 ories, and the latter associating these centers with that 
 of speech. In front of the fissure of Sylvius is a scheme 
 representing the tracts for automatic movements of the 
 hand produced by visual and aural impressions; and still 
 more anterior, a tract connecting the center for movements of 
 the hand with the speech center, through which the latter 
 center may be excited by movements of the hand, in the event 
 of a lesion of the direct tracts between the aural and visual 
 memories and the speech center. 
 
FK'ure 3. 
 
80 ARCHITECTURE OF THE BRAIN. 
 
 Figure 4. Fornix and lateral ventricles. In the median 
 line from before backwards are: (1) the anterior median fissure 
 at the posterior extremity of which is a lateral fissure, the 
 ventricle of the corpus callosum, (2) the genu of the corpus 
 callosum, (3) septum lucidum, containing the fifth ventricle, 
 (4) the fornix, the anterior pillars of which bending down- 
 ward bound the foramena of Monro in front; upon 
 the upper surface, in the median line, is an elevated ridge 
 which forms the attachment of the fornix to the under surface 
 of the corpus callosum, (5) the splenium of the corpus cal- 
 losum, posterior to which is a part of the ventricle of the 
 corpus callosum, and (6) the posterior median fissure. 
 
 On each side of the median line are the lateral ventricles, 
 basal ganglia and internal capsules, corona radiata and the 
 hemispherical ganglia. The lateral ventricle is divided, into a 
 body, an anterior, middle, and posterior cornua. The ventricle 
 is bounded externally in front by the internal capsule, upon 
 which the functions of its parts are indicated. Behind the cap. 
 sule is a broad groove leading from the body of the ventricle 
 to the middle and posterior cornua. The posterior portion of 
 the capsule bends downward and is called its genu. The body 
 of the ventricle contains from within outward; (1) the fornix 
 and corpus fimbriatum, (2) fissure of Bichat, (3) choroid 
 plexus, (4) part of the thalamus opticus, (6) t^nia semicircu- 
 laris, (6) caudate nucleus. The anterior cornu contains the 
 head of the caudate body; the middle cornu, the hippocampus 
 major, and pes hippocampi; the posterior cornu contains the 
 hippocampus minor; and between these cornua is the pes acces- 
 sorius or eminentia collateralis. The tail of the caudate 
 body, taenia semicircularis, choroid plexus, and corpus fim- 
 briatum descend together along the inner margin of the 
 middle cornu to the apex of the ungual convolution. See 
 Figs 5, 7, 17. The hemispherical ganglia constitute the 
 grej- matter which encloses the corona radiata. 
 
Figure 4. 
 
82 ARCHITECTURE OF THE BRAIN. 
 
 Figure 5. A horizontal and lateral view, with the foinix 
 divided and reflected, exposing the velum interpositum. In 
 the median line from before backward are seen: (1) the anterior 
 median fissure, (2) genu of the corpus callosum, (3) septum 
 lucidum and fifth ventricle, (4) anterior pillars of the fornix, 
 (6) velum interpositum, triangular in shape, fringed by the 
 choroid plexuses, and containing the vense Galeni and choroid 
 arteries, and, at its center behind, an elevation denoting the 
 position of the pineal gland. (6) Behind the velum is 
 the reflected fornix and corpus callosum, upon which are 
 seen transverse striae, the lyra. The attachment of the 
 fornix to the corpus callosum is seen in the middle of the 
 section of these parts. Behind the corpus callosum, is 
 the posterior median fissure. The parts forming the 
 floor of the lateral ventricle, as well as the internal cap- 
 sule, are shown in figure 4. The oblique view presented 
 by this figure exposes fully the middle and posterior cornua 
 and the parts contained in them, also the situation and extent 
 of the corpus fimbriatum, transverse fissure, and choroid 
 plexus, as well as the manner in which they encircle behind 
 the genu of the internal capsule into the middle cornu. 
 A complete view of the pes hippocampi and pes accessorius is 
 ex|)08ed. At the lower and anterior extremity of the middle 
 cornu is a transverse section of the lenticular nucleus, external 
 capsule, claustrum, insula and Sylvian fissure. Below the 
 lenticular body, or external basal ganglion, is a tract of 
 transverse fibres, which is a section of the inferior ramus of 
 the internal capsule. See figure 7. The inferior ramus of 
 the internal capsule forms the roof of the middle cornu. In 
 the roof of the middle cornu which has been removed in this 
 dissection are the taenia semicircularis and the tail of the cau- 
 date nucleus lying parallel to the optic tract. See figure 7. 
 
Figure 5. 
 
84 ARCHITECTURE OP THE BRAIK. 
 
 Figure 6. In this dissection, the velum interj^ositum and 
 the right occipital and temporal lobes are removed, exposing 
 the third ventricle, pineal gland, corpora quadrigemina, basal 
 ganglia, and the upper surface of the cerebellum. Figure 7 
 is a lateral view of the same dissection, and shows the relation 
 of the external basal ganglion, or lenticular nucleus, to the 
 internal capsule; also the posterior extremities of the caudate 
 nucleus and t;^nia semi-circularis, as they descend behind 
 the genu of the internal capsule into the roof of the middle 
 coruu of the lateral ventricle. 
 
 In the median line from before backward (Fig. 6) are 
 seen: the anterior median fissure, genu of the corpus callosum, 
 septum lucidum enclosing the fifth ventricle, the divided 
 anterior pillai's of the fornix, the third ventricle containing 
 three commissures, anterior, middle, and posterior, the pineal 
 gland and its pillars, corpora quadrigemina divided into four 
 tubercles by a crucial depression, the incisui'a anterio of the 
 cerebellum, the superior vermiform process, and the inclsura 
 posterior. Laterally: in front, is the corona radiata; in the 
 middle, the internal and external basal ganglia, separated by 
 the internal capsule; and behind, the upper surface of a lateral 
 lobe of the cerebellum, made up of the lobus quadratus and 
 the posterior, or semilunaris lobe. The internal basal ganglia 
 are, the caudate nucleus and the thalamus opticus, divided 
 by the taenia semicircularis, which lies in a depression between 
 them. The thalamus is composed of four distinct bodies; 
 (1) the pison (pea), a small body at the junction of the 
 anterior pillar of the pineal gland with the body of the 
 thalamus, (2) the pulvinar, pointed in front opposite the mid- 
 dle commissure, and continuous behind with the external 
 geniculate body and outer division of the optic tract, (3) the 
 tuberculum, a nodule at the anterior exteremity of the thala- 
 mus, continuous with a slim tract of white fibres directed back- 
 ward and outward, along a groove on the upper surface of the 
 thalamus which lodges the corpus fiimbriatum, (4) the fusi- 
 formis, which is an oblong elevation lying on the outer 
 border of the thalamus, internal to the taenia semicircularis. 
 
Figure 6. 
 
86 AECHirECTURE OP THE BRAIN. 
 
 Figure 7 is a lateral and inferior view of the same dissection as figure 6, 
 from which may be studied on the right of the figure (left side of the brain) 
 the parts seen upon the base of the brain. On the left side of the figure 
 are seen; the tracts of the medulla oblongata, the expansion of the crus 
 cerebri into the internal capsule, and the relation of the capsule to the 
 lenticular nucleus, to the optic tract, taenia semicircularis, and tail of the 
 caudate nucleus. The pons is divided to show the descent of the crusta, 
 and the continuation of a portion of its fibres into the anterior pyramid 
 of the medulla. The under surface of the cerebellum is also exposed, and 
 in conjunction with figure 6 the parts of this portion of the brain can be 
 studied. The following parts are seen on the base of the brain from 
 before backward in the median line : (1) anterior median fissure, (2) 
 lamina cinerea (hidden by the optic commissure), (3) optic commissure, 
 nerves and tracts, (4) interpeduncular space, bounded by the optic tracts 
 and cerebral peduncles, and containing, the tuber cinereum, infundibulum 
 and pituitary body (removed), corpora albicantia, posterior perforated 
 space and third nerves, (5) the pons Varolii, (6) the medulla oblongata. 
 On the outer side from before backward are: (1) the orbital convolutions, 
 (2) olfactory bulb, and nerve terminating in three roots, (3) the anterior 
 perforated space, upon which is the anterior pillar of the corpus callosum 
 (4) the fissure of Sylvius, (5) temporal lobes, (6) crug cerebri and fourth 
 nerve, (7) great transverse fissure, and (8) the flocculus and under surface 
 of the cerebellum. The cranial nerves are numbered from before back- 
 ward: 1st, olfactory; 2nd, optic; 3rd, motor oculi; 4th, pathetic; 5th, 
 trigeminus; 6th, abducent; 7th, facial; 8th, auditory; 9th, glosso-phar- 
 yngeal; 10th, pneumogastric ; 11th, spinal accessar}-; 12th, hypoglossal. 
 
 On the left side of the figure behind, is the incisura posterior and 
 inferior vermiform process, lobes of the cerebellum, tracts of the medulla, 
 arciform fibres, olive, crusta, optic tract and geniculate bodies, and the 
 inferior extremities of the taenia semicircularis, tail of caudate body 
 ending in a bulbar extremity, and the auricular expansion of the fibres of 
 the internal capsule enclosing the lenticular nucleus. Upon the surface of 
 the lenticular body is a fragment of the external capsule, at the inner 
 angle of which is (AC) the outer extremity of the anterior commissure of 
 the third ventricle. 
 
 The internal capsule is divided into four parts : the anterior, which 
 is hidden by the frontal lobe; the middle, which is the motor portion; the 
 posterior, containing the fibres of common sensation and the optic radiation; 
 and inferior ramus of the capsule to the temporal convolutions, which 
 contains the tracts of hearing, If ste, and smell. 
 
( '. 1 ^ 
 
 
 
 
 ^^tu^ 
 
 
 \ ^^ '^^F^ 
 
 
 ■^ 1^3* A 
 
 -^ 
 
 ^ ^^^Mfr 
 
 - 
 
 ^ S^i*^Kn 
 
 
 ^ en rm. 
 
 ^ 
 
 ^', 
 
 
 "^v 
 
 c 
 
 
 Figure 7. 
 
88 AKOHITEOTURE OF THE BRAIN. 
 
 Figure 8. Figures 8 and 9 are posterior and lateral views of the same 
 dissection, in which the hemispheres and the cerebellum have been removed 
 giving a complete view of the intermedia. 
 
 This figure can be divided into three sections: a superior or cerebral, a 
 middle or peduncular, and an inferior or medullar} 
 
 At the upper, or anterior part of the superior division is a part of the 
 corpus callosum crossing above the anterior horns of the lateral ventricles, 
 and uniting at its lateral extremities with the intei'ual capsules. The corpus 
 callosum and the capsules enclose, as in a triangle, the ventricles and the 
 internal basal ganglia, caudate nuclei and thalami optici. The caudate 
 nucleus of the left side has been removed in order to show the distri- 
 bution of fibres from the thalamus to the iuternal capsule, and also the 
 fibres which emerge from between the lamiaa of the capsule to reinforce the 
 taenia semicircularis as it passes forward into the anterior horn of the lateral 
 ventricle. The fornix lies over the third ventricle, and, in its middle is 
 joined to the uuder surface of the corpus callosum by the septum lucidum, 
 which contains thefifth ventricle, and separatesthe anterior horus of the lateral 
 ventricles. The posterior part of the thalamus winds around the crus cere- 
 bri to be continuous with the optic tract. The opening to the third ventricle 
 is surrounded by the pineal body and its anterior peduncles, and upon each 
 side in the front of the pineal body is a small tubercle ot^ gi'^y matter, 
 called the pison. At the posterior extremity of the thalamus are two emi- 
 nences, one on each division of the optic tract, the corpora geniculata, 
 externum and internum. Between the thalami are four tubercles, divided 
 by a crucial depression, the corpora quadrigmina, or nates and testes. Di- 
 rected obliquely outward from the nates and testes to the geniculate bodies 
 are the brachia, anterius and posterius. 
 
 The middle division contains from within outward: the valve of 
 Vieussens, processes and fourth nerves, fundamental root zones and crustte. 
 A vertical groove upon each crus cerebii lies between the root zone and 
 the crusta. Lower down, on either side, the relations of the parts are from 
 the median line outward: the valve of Vieussens, processus, corpus denta- 
 tum, restiforni body, and the pons Varolii. These latter parts form an 
 arch or roof over the fourth ventricle. 
 
 The inferior division is broad above, and flattened beneath the arch 
 formed by the parts just mentioned, where it presents a triangular depressed 
 surface which is part of the floor of the fourth ventricle. This surface is 
 crossed by the roots of the seventh and eighth nerves, the stride trausversse. 
 In the median line is the posterior median fissure of the fourth ventricle, 
 which terminates below in the central canal of the spinal cord, and is con- 
 tinuous with the posterior median fissure of the medulla oblongata. Bound- 
 ing the sides of the floor of the fourth ventricle are the restif orm bodies, and 
 at the apex of the ventricle are two eminences on each side, the anterior are 
 the restiform nuclei, and the posterior, the clavate nuclei. The lower portion 
 of this division is rounded, the columns of which it is constituted are sim- 
 ilar to those of the spinal cord, a section of which is seen on the end. 
 
■ / 
 
 \ J 
 
 Figure 8. 
 
90 ARCHITECTURE OF THE BRAIN. 
 
 Figure 9. For the convenience of description, figure 9 may be divided into four 
 portions: cerebral, peduncular, pons, and medullary. 
 
 In the center of the cerebral portion is the lenticular nucleus, or external basal 
 ganglion, which is bounded above by the deep fibres of the external capsule, the super- 
 ficial fibres having been removed in order to expose the ganglion. The external capsule, 
 is derived from the outer surface of the ganglion, and its fibres radiate upwards in the 
 middle, and in front and behind, they are directed obliquely forward and backward (See 
 Fig. 19). Tbe internal capsule receives the fibres of the external capsule, radiates forwaid 
 where it is called the fillet, upward in the middle, which are its motor fibres, and behind 
 and below, which are the sensory and memory divisions of the capsule. The external longi 
 tudinal commissure extends from the sensory radiation of the internal capsule to its fillet 
 division, which it joins in front of the lenticular nucleus. The commissure lies beneath the 
 lenticular body and upon, or rather within the inferior, or temporal radiation of the 
 internal capsule. Beneath the longitudinal commissure and the inferior ramus of the 
 internal capsule are, from behind forward : the corpora quadrigemina, geniculate bodies, 
 the upper and lower divisions of the optic tract, the optic tract commissure and nerves, 
 and the lamina cinerea. 
 
 The peduncular division contains from behind forward, the processus, the fourth 
 nerve, fundamental root zone, vertical groove, crusta cerebri, and interpeduncular space 
 containing the tuber cinereum, infundibulum, corpora albicantia, posterior perforated 
 space and third nerves. The latter parts, together with the optic commissure and lamina 
 cinerea form the floor of the third ventricle. 
 
 The region of the pons Varolii contains from before backwards: (1) the superficial 
 or commissural layer, the upper fibres of which are derived from the raphe and floor of 
 the fourth ventricle, and enter the cerebellum along with the restiform body, to be dis- 
 tributed to the corpus dentatum; (2) the reticu'ated layer, or formatio reticularis of the 
 pons, composed of the fibres of the crusta, anterior pyramid of the medulla, and the 
 deep layer of the pons, interspersed with grey matter, and is the nucleus of the pons, or 
 external basal ganglion of the cerebellum; (3) the fillet, composed of four layers: funda- 
 mental root zone, olivary fasciculus, anterior root zone, fillet tract from fourth ventricle; 
 (4) the fifth, seventh and eighth nerves, which pass through the restiform triangle (see 
 figures 10-12) into the floor of the fourth ventricle, the roots of the latter two nerves 
 form the striae transvorste on the floor of the ventricle (figures 8-10) ; the sixth nerve 
 winds beneath the pons and joins the fillet; (5) the reflected superior portion of the 
 arch of the restiform body, corpus dentatum and posterior root of the auditory nerve. 
 
 The medulla oblongata in its upper half is composed of parts from the median 
 fissure backward: the anterior pyramid overlying the fundamental root zone, the olivary 
 body, anterior root zone, and the restiform body, composed of the arciform fibres 
 of the anterior pyramid, the direct cerebellar tract, and the posterior root zone. The 
 restiform body contains the restiform ganglion at its lower extremity. Burdach's column, 
 the posterior pyramid and clavate nucleus, are behind, and are not seen in the figure (see 
 figure 8). The lower part of the medulla contains the same parts except the olive. The 
 decussation of the anterior pyramids are in front, about midway from the pons and the 
 lower end of the figure. The lower extremity of the decussation marks the limit of the 
 medulla oblongata, below which is the spinal cord, the columns of which can be read 
 upon the figure. 
 
Figure 9. 
 
92 ARCHITECTURE OF THE BRAIN. 
 
 Figure 10. Dissection of the pons and basal region of the cerebrum, viewed from 
 behind. The parts upon the right half of the figure are retained in order to show the 
 relations of the parts uncovered by the dissection upon the left side. In the median line 
 in front is a section of the genu of the corpus callosum and septum lucidum, the anterior 
 pillars of the fornix, the third ventricle, the fasciculi teretes and posterior median fissure 
 of the iter and fourth ventricle, the calamus scriptorius, clavate nuclei, and the posterior 
 median fissure nf the medulla oblongata and spinal cord. The calamus scriptorius (pen) 
 is situated between the restiform bodies, and its point is between the clavate nuclei, at 
 the conjunction of the posterior median fissure of the medulla, and that of the floor of 
 the fourth ventricle with the upper extremity of the central canal of the spinal cord 
 (compare with Fig. 26, at R). 
 
 Upon the right side of the figure, the parts seen from before backward are: a portion 
 of the corpus callosum and the internal capsule, the anterior horn of the lateral ventri- 
 cle, caudate nucleus, tsenia semicircularis, the thalamus opticus and anterior 
 pillar of the pineal gland, the pison, posterior commissure, pineal body, corpora quadri- 
 gemina and brachia, the processus, valve of Vieussens, and corpus dentatum. Beneath 
 are: the fourth ventricle at its widest part, the arch of the restiform body, the 
 restiform triangle, through which the roots of the seventh nerve and the anterior root of 
 the eigth nerve emerge into the fourth ventricle, the former crossing the floor of the 
 ventricle to enter the raphe, and the latter to join a tract, internal to the restiform body, 
 which passes from the auditory nucleus of the medulla to the fillet. The tract just men- 
 tioned forms the posterior layer of the fillet (see figure 13, designation 4i, and divides 
 the restiform triangle into two portions, an anterior part, which transmits the roots of 
 the seventh and eighth nerves, and an inferior part, through which the fifth nerve passes 
 in front of the fasciculi teretes. Beneath the arch of the restiform body is the posterior 
 root of the eighth nerve, which crosses the floor of the fourth ventricle to reach the raphe. 
 This root of the eighth and that of the seventh are the striae transversse on the floor of 
 the ventricle. At the lower extremity of the restiform body is the restiform nucleus (see 
 section of restiform nucleus, figure 86). The clavate nucleus is internal and below the 
 restiform nucleus and is superficial, while the latter is imbedded beneath a layer of white 
 fibres. The posterior pyramid of the medulla, Gall's column, terminates above in the 
 clavate nucleus, and the posterior root zone, column of Burdach, in the restiform nucleus. 
 
 On the left side, from before backward are: portions of the caudate nucleus and thal- 
 amm, anterior fibres which pass forward to the internal capsule in conjunction with 
 the fillet of the pons Varolii, and are distributed to tbe anterior lobe of the cerebrum. 
 The red nucleus, or snbthalmic ganglion is exposed, and is seen in relation with the fas 
 ciculi teretes and the wall of the third ventricle internally, and with the fillet externally. 
 The red nucleus gives off fibres to the thalamus and in front to the fillet, and behind, a large 
 cord continuous with the opposite processus, which decussates with the processus 
 of the same side beneath the fasciculi teretes, under the floor of the iter. External to 
 the red nucleus, the processus and its decussation, are successively from within outward: 
 the fillet, locus niger, and the crusta above; and the fundamental root zone and pons 
 Varolii below. Below the crusta are the uppermost fibres of the pons Varolii, which form 
 a tract derived from the floor of the fourth ventricle, that entering the raphe, passes for- 
 ward to the posterior perforated space, and winding around the front of the crus cerebri, 
 is directed backward to the restiform body, with which it enters the cerebellum. Below 
 the posterior extremity of this tract, is seen the divided extremity of the restiform body 
 enclosed by the roots of the eighth nerve, the seventh nerve passes through the resti- 
 form triangle in company with the anterior root of the eighth, to enter the fourth ventri- 
 cle. Above the restiform body, the parts from within outward are: the fasciculi teretes 
 and floor of the fourth ventricle, the four layers of the fillet, and the deep and superficial 
 layers of the pons Varolii. The word fillet is written upon the fundamental root zone (see 
 figure 11). The fifth nerve is seen passing under the floor of the ventricle between the 
 deep layer of the fillet and the anterior root zone. The parts forming the posterior and 
 lateial surfaces of the medulla can be read upon the figure. 
 
Figure 10. 
 
94 AEOHITECTUEE OF ThJ BRAIN. 
 
 Figure 11 — Is a dissection in which the right pyramid of the medulla, 
 the right half of the pons, and the lower portion ot the crusta are removed, 
 exposing the continuity of the fundamental root zon^, from the spinal cord 
 to its termination in the testes and brachium posti. rius. In the cord, 
 it is seen to lie external to the direct pyramidal tract (column of Turck); in 
 the medulla as far above as the olive, it is superficial ind external to the 
 anterior pyramid. Opposite the olive, it is compresset into a prismatic 
 shape (figure 36) between this body and the raphe. Upoi the anterior sur- 
 face of the fillet and processus, it is a flat band of fibres terminating 
 above and behind in the testes and brachium posterius. T'lis tract is prob- 
 ably a part of the visual reflex system, by which a pers> n affected with 
 ataxia is able to maintain the upright position while the eyes are open. 
 
 The lower extremity of the figure shows the superficif 1 tracts which 
 form the anterior and lateral columns of the cord, viz. : the cclumn of Tiirck 
 and the fundamental root zone of the anterior column; and tl e anterior root 
 zone and direct cerebellar tract, of the lateral column of the cord. In the 
 middle of the medulla is the decussation of the pyramids and a flattening 
 of the fundamental zone for its accommodation. The upper part of the 
 medulla is seen to be connected with the pons and the cen bellum by: (1) 
 the anterior pyramid with the reticulated layer; (2) the fuodamental root 
 zone, olivary fasciculus, anterior root zone, and fasciculus from the fourth, 
 ventricle forms the lemniscus or fillet; (3) the grey matter of the cord 
 forms the fasciculi teretes (not seen); (4) the restiform body connects the 
 posterior part of the medulla with the cerebellum. 
 
 The restiform triangle is enclosed, by the edge of the fiFet in front, the 
 restiform body behind, and the processus above. The parts transmitted by 
 the triangle are seen in figures 9 and 10. Above the pons are from before 
 backward: the optic nerves, commissure and tracts, interpeduncular space, 
 crusta, locus niger, geniculate bodies, brachia and corpora quadrigemina. 
 Above the optic commissure is the lamina cinerea. 
 
^">ind 
 
 Figure 1) . 
 
96 ARCHITECTURE OF THE BRAIN. 
 
 Figure 12 — may conveniently be observed in four divisions. 
 The upper portion, above the optic tract, shows the three 
 divisions of the lenticular nucleus, surrounded by the internal 
 capsule, upon which is marked its divisions, into fillet, motor, 
 and sensory portions. The anterior part is connected with 
 the optic commissure by the lamina cinerea. The second 
 portion of the figure is between the lower arm of the internal 
 capsule and the upper border of the pons; containing the 
 optic nerves, commissure, tracts, and the corpora geniculata, 
 the tuber ciuereum and iufundibulum, corpora albicantia, pos- 
 terior perforated space, crusta, locus niger, upper extremity 
 of the fundamental root zone, brachia, corpora quadrigemia, 
 and pineal body. The third portion contains: in front, a sec- 
 tion of the transverse fibres and reticulated part of the pons, and 
 a part of the raphe; further back, the fillet proper, consisting of 
 the olivary fasciculus, (which is fully exposed by the removal 
 of the fasciculus of the fundamental root zone), the anterior 
 root zone and a fasciculus from the inner side of the restiform 
 body, derived from the floor of the fourth ventricle. Upon 
 the external margin of the fillet is the restiform triangle, con- 
 tained behind by the restiform body and the processus, which 
 terminate in the corpus dentatum of the cerebellum. Above 
 and below the fillet, are seen the divided ends of the funda- 
 mental root zone. The lower portion of the figure shows the 
 parts which form the medulla oblongata, the decussation of 
 its anterior pyramids, and a section of the spinal cord. 
 
f 
 
 <?-, 
 
 -r 
 
 A "^ 
 
 o< ^^H 
 
 
 < < ^^ 
 
 0^ 
 
 
 
 ( • 
 
 -y 
 
 
 
 N 
 
 Figure 12. 
 
98 ARCHITECTURE OF THE BRATN. 
 
 Figure 13. In this figure, the right pyramid of the me- 
 dulla, and the right half of the pons, and crusta, have 
 been removed. Sections of the four layers of the fillet 
 have also been removed. The lower ends are marked: 
 (1) tlie fundamental root zone; (2) olivary fasciculus; (3) 
 the anterior root zone, or lateral tract of the medulla; 
 (4) layer from the floor of the fourth ventricle, beneath 
 which is seen the anterior surface of the fasciculi teretes. 
 Internal to these layers is the raphe, and a section of the 
 pons, consisting of a reticulated and a commissural layer. 
 External to the fillet is the restiform triangle, restiform 
 body, and processus; (5) the fifth nerve. The processus 
 arises behind from the corpus dentatum, is directed upward 
 beneath the fundamental root zone and the fillet, and inward 
 in front of, or under the fasciculi teretes, to decussate with the 
 opposite processus in the raphe of the crus cerebri, (see PT, 
 figure 26). Above the decussation, the fibres of the opposite 
 processus are seen to terminate in the red nucleus, which is un- 
 covered in the figure by the removal of a section of the fillet. 
 Above the red nucleus the fillet is seen to pass upward and 
 forward, beneath the fibres of the internal capsule derived 
 from the crusta, to join the anterior portion of the capsule. 
 The anterior commissure of the third ventricle, in its passage 
 outward to the temporal lobe, pierces the anterior border of 
 the fillet. The three divisions of the internal capsule are 
 indicated upon the figure. 
 

 ■■by ^- 
 
 Figure 13. 
 
100 ARCHITECTURE OF THE BRAIN. 
 
 Figure 14 illustrates from above downward: the inner 
 layer of the internal capsule; the lining membrane of the 
 lateral ventricle which forms the bed of the caudate nucleus; 
 the thalamus opticus, composed of concentric layers of 
 fibrous matter between which vesicular layers are inter- 
 posed; the divided extremity of the anterior commissure 
 of the third ventiicle; the lamina cinerea, optic tract, and the 
 parts in the interpeduncular space; the red nucleus, from 
 which a tract passes forward to the fillet; behind the red 
 nucleus are the corpora quadrigemina, from which the brachia 
 pass outward and upward beneath the geniculate bodies to the 
 internal capsule; below the red nucleus is the decussation of 
 the processes, thiough the raphe of the crura cerebri; the 
 processus, fillet, and the restiform body enclose the restiform 
 triangle, in front of which are: the root of the fifth nerve, the 
 deep portion of the fasciculi teretes, the divided ends of the 
 layers of the fillet, the raphe and pons; below the pons are 
 the tracts of the upper portion of the medulla, except the 
 anterior pyramid, which has been removed; the lower extrem- 
 ities of these tracts have also been removed, in order 
 to expose the crossing of the fibres of the opposite anterior 
 pyramid to form the deep fibres of the lateral column of the 
 cord. The fibres of the crossed pyramidal tract are seen to 
 interrupt the anterior grey column in their passage from the 
 pyramid to the opposite lateral column of the cord. 
 
Piniial Gloried 
 Nafes 
 Testes 
 
 Re.sf. thicinq} 
 
 ^iJi-p. Oe 
 
 Figure 14. 
 
102 AECHITECTUEE OF THE BRAIN. 
 
 Figure 15 — Begianing from helow, shows: (1) a section 
 of the spinal cord, and of the columns of grey and white 
 matter, commissure, and central canal; (2) the columns upon 
 the posterior surface of the medulla, the clavate, and the 
 position of the restiform nuclei; (3) the fourth ventricle, fas- 
 ciculi teretes, calamus scriptorius, and the parts which bound 
 the fourth ventricle, viz.: the restiform bodies and the processes; 
 (4) the dentate bodies, and the relation of the peduncles of the 
 cerebellum; the superior peduncle enters the under surface of 
 the dentate body, the inferior arches upward and backward be- 
 tween the superior and middle peduncles, and is also connect- 
 ed with the corpus dentatum, while the middle peduncle is 
 external, and has no connection with that body; (5) the pro- 
 cesses, above, are seen to decussate beneath the fasciculi 
 teretes, each to connect with the red nucleus of the opposite 
 side; (6) between the red nuclei are the third ventricle, and 
 middle commissure. From within outward on either side are: 
 the third ventricle and the grey matter upon its sides, the red 
 nucleus, fillet, locus niger, and crusta. The fundamental 
 root zone is seen to be in apposition with the posterior margin 
 of the fillet; its divided extremity has been exposed by the 
 removal of the corpora quadrigemina. (7) The grey columns 
 of the cord are spread out upon the floor of the fourth ven- 
 tricle and continued through the iter to the third ventricle by 
 the fasciculi teretes. 
 
Figure 15. 
 
104 AECHITECTUEE OF THE BRAIN. 
 
 Figure 15i represents a dissection in which the upper por- 
 tion of the cerebellum has been removed by separating the 
 sides of its transverse fissure and dividing the superficial 
 layer of the middle peduncle. The upper portion is torn off 
 from behind forwards, exposing the corona radiata and the 
 upper surface of the corpus dentatum. The deep fibres of 
 the middle peduncle are seen to pass directly into the corona 
 radiata, to be distributed to the hemispherical ganglion of the 
 cerebellum. The superior peduncle passes beneath the corpus 
 dentatum to enter its hilus; and the inferior peduncle, or resti- 
 form body, springing up from between the superior and mid- 
 dle peduncles, arches backward and is distributed to the upper 
 surface of the dentate body. The corona radiata is made up 
 of radiating fibres from the middle peduncle, and from the 
 corpus dentatum. The corpora quadrigemina, and fasciculi 
 teretes of the iter, have been removed in order to show the 
 decussation of the processes and their connection with the red 
 nuclei. Above the decussation is the raphe, on either side of 
 which is the red nucleus, fillet, locus niger, and crusta. Be- 
 hind the crusta is the vertical line of the crus cerebri and the 
 divided extremity of the fundamental root zone. Below the 
 decussation are the divided ends of the fasciculi teretes and the 
 iter, the valve of Yieussens, and, lower down, between the 
 corpora dentata, is the white substance of the middle lobe 
 of the cerebellum. 
 
Figure 15^. 
 
THE CEREBEAL HEMISPHERE. 
 
 Superior border. 
 Figs. 1-16-IV-24. 
 
 External border. 
 Figs. 2-7-16-17- 
 24-25. 
 
 Inferioi 
 Figs. 
 
 border. 
 1-17-26. 
 
 Separated from the remaining portion of the axis, the 
 cerebral hemisphere in general view resembles the quarter 
 section of an ovoid. It is elongated from before backwards, 
 bluntly pointed at each extremity, and presents for examination) 
 three borders which enclose three surfaces. The borders are: 
 superior, external, and inferior. The superior border forms 
 the margin of the great longitudinal fissure, its convexity is 
 upward, and it extends from the posterior extremity of the 
 occipital lobe to the anterior angle of the orbital surface of the 
 frontal lobe of the hemisphere, dividing the external from 
 the internal surface. The external border arches around the 
 anterior border of the orbital surface of the frontal lobe to the 
 fissure of Sylvius, and around the outer border of the tem- 
 poral and occipital lobes to the posterior extremity of the 
 hemisphere, where it joins the superior border at an angle. This 
 border is interrupted by a broad notch opposite the fissure 
 of Sylvius, which receives the posterior arched border of the 
 orbital plate of the frontal and sphenoid bones. Behind the 
 projection of the temporal lobe this border is arched upward 
 over the cerebellum. It forms a notch in front with the cere- 
 bellum which lodges the petrous portion of the temporal bone, 
 and marks the position of the external auditory meatus. 
 This border separates the external and the inferior surfaces. 
 The inferior border is internal along the median line of the 
 base of the cerebrum and is in three portions. The anterior 
 and posterior portions form the margins respectively of the 
 anterior and posterior median fissures. The middle portion 
 crosses the hilus of the hemispherical ganglion, dividing it into 
 
 106 
 
THE CEREBRAL HEMISPHERE. 107 
 
 two unequal jxirts: that below, assists in the formation of the 
 hilus of the cerebrum, and that above, is called the intrafissural 
 portion of the hilus, because it is surrounded by the great 
 longitudinal fissure. Crossing this border at the junction of 
 its anterior and middle portion is a broad groove continuous 
 laterally with the anterior perforated space, and in front with 
 the anterior surface of the corpus callosum. This groove is 
 converted into a foramen by the optic nerve, and lodges the 
 anterior cerebral artery. The bottom of the groove is con- 
 vex from within outward, resembling a large cord, and is 
 named the cordon, because, in the early development of the 
 brain this part forms the connection of the hemisphere to the 
 parts below it, and because, the convolutions of the cerebrum 
 can be traced as loops, which begin and end in this locality. 
 The cordon is composed of a large mass of antero-posterior 
 fibres disposed in horizontal laminte. 
 
 The surfaces of the hemisphere are: external, inferior, and 
 internal. The external surface is pointed before and behind, 
 and convex in every direction, corresponding to the concavity 
 of the inner surface of the vault of the cranium, with which 
 it lies in contact. Behind the center of this surface is an 
 oval eminence corresponding to the parietal eminence of the 
 skull, which is situated vertically above the external auditory 
 meatus. The vertex is midway betweeii the occiput and the 
 nasion, and is in a direct line with the parietal eminence 
 and the external auditory meatus. The relations of these 
 points to the external surface of the hemisphere are of oreat 
 assistance in locating the lobes and fissures beneath the surface 
 of the head. 
 
 This surface of the hemisphere is marked by two promi- 
 nent fissures, the fissures of Sylvius and of Eolando- and bv """ ''°'"°"^° 
 
 ' '"""-* "JJ Figs. 16 34. 
 
 minor fissures that separate the convolutions and the lobes 
 a7id are named after the parts which they divide. 
 
 16 i4-25. 
 
 f Sylvius 
 and 
 Figs. 16 34. 
 
108 
 
 AECHITECTUEE OF THE BRAIN. 
 
 Insula. Fig. 18. 
 
 of Sylvius on 
 urface cf the 
 
 .n of the fis- 
 □ f Rolando. 
 
 Tlie fissure of Sylvius begins at the anterior perforated 
 space, winds in front of, to the outer side, and above the 
 temporal lobe, where it divides into a short and long arm; 
 the former projecting upward and forward into the frontal 
 lobe, and the latter is directed backward to the middle of 
 the parietal eminence. This fissure is very deep and branched 
 at its bottom to enclose a bunch of convolutions, called the 
 insula, or island of Eiel. The insula is exposed by separat- 
 ing the margins of the fissure of Sylvius, and the convolu- 
 tions which cover it are called the operculum — a name which 
 must not be confounded with the aperculum, or hilus of the 
 hemispherical ganglion. The position of the fissure of Syl- 
 vius is indicated upon the surface of the head by a line 
 drawn from the outer canthus of the eye to the middle of the 
 parietal eminence, and if continued this line would pass through 
 the crown and the opposite external auditory meatus. 
 
 The fissure of Rolando extends from the middle of the 
 posterior arm of the fissure of Sylvius, upward and slightly 
 backward to the vertex, dividing the external surface of the 
 hemisphere into anterior and posterior parts, from which it 
 derives the name of central fissure. Its situation is indicated 
 upon the surface of the head as lying beneath the upper por- 
 tion of a line extending from the inferior angle of the malar 
 bone to the vertex. The convolutions upon the external sur. 
 face of the hemisphere are represented upon figure 16, and 
 are named: first, second and third, in the several regions of 
 the surface, viz.: frontal, parietal, occipital, and temporal, 
 with the exception of the central region, in which there are 
 only two convolutions, the anterior and posterior central, one on 
 each side of the central fissure of Rolando; and the insular 
 region consists of five or sis small convolutions contin- 
 uous with those of the sides of the fissure of Sylvius. 
 
THE CEREBRAL HEMISPHERE. 
 
 109 
 
 Inierior surface of 
 a hemisphere. 
 Figs. 2 17. 
 
 Orbital portion. 
 
 Temporo-occipital 
 portion. 
 
 The inferior surface of the hemisphere, before descri?jed 
 with the under surface of the cerebrum, re(_[uires a short 
 review in this connection. It is divisible in three portions: 
 an anterior or orbital portion, which is triangular, concave 
 from side to side, and elevated upon its internal border, where 
 it is marked by a longitudinal fissure which lodges the olfac- 
 tory bulb and nerve. It is marked by three indistinct con- 
 volutions: anterior, external, and posterior. The temporo- 
 occipital surface looks obliquely inward, is concave from 
 before backward, and is marked by several convolutions, the 
 outermost of which is the under surface of the third temporal 
 convolution, internal to which in succession are: the fusiformis, 
 lingualis, and hippocampal convolutions. The latter is con- 
 tinuous behind the splenium of the corpus callosum, with the 
 convolution of the gyrus, and in front with the ungual, a 
 small convolution which is turned inward upon the margin of 
 the hilus cerebri. The remaining portion of this surface con- 
 sists of a crescent depression which includes the interpedun- 
 cular space and the divided surface of the crus cerebri, around 
 the outer margin of which is the fissure of Bichat. 
 
 The internal surface of the hemisphere presents two por- 
 tions for examination: a convoluted portion above, in front, 
 and behind; and an enclosed portion, presenting the divided 
 surfaces of commissures and the lateral wall of the third 
 ventricle, which together fill up the upper part of the aper- 
 culum or hilus of the hemispherical ganglion, before called 
 the iutrafissural portion of the hilus. The convoluted convoluted port 
 portion of the internal surface of the hemisphere encloses the 
 outer surface of the corpus callosum, from which it is separ- 
 ated by the fissure of the gyrus fornicatus, or ventricle of the 
 corpus callosum. It is wider behind than in front, and shaped 
 like the falciform process of the dura mater, against which it 
 lies; its posterior border, which is the margin of the posterior 
 
110 
 
 ARCHITECTURE OF THE BRAIN. 
 
 Intrafissural regi( 
 of the internal 
 surface of the 
 
 median fissure, rests upon the tentorium cerebelli. This por- 
 tion of the internal surface is marked by two distinct fissures, 
 the calloso-marginal, and parieto-occipital. The anterior fis- 
 sure, calloso-marginal, begins in front beneath the genu of 
 the corpus callosum, and, winding in front and above this 
 body is directed upward and backward to terminate upon the 
 margin of the great longitudinal fissure behind the vertex and 
 the upper extremity of the central fissure of Rolando. The 
 calloso-marginal fissure is separated from the corpus callosum 
 by the convolution of the gyrus fornicatus. The parieto- 
 occipital fissure begins below the hippocampal convolution 
 upon the inferior surface of the hemisphere, extends upward 
 and backward, across the internal border and internal surface, 
 to a point upon the margin of the longitudinal fissure which 
 lies beneath the crown of the head. Above the inferior or 
 internal border of the hemisphere it gives off a branch fissure, 
 the calcarine, which passes backward to the posterior extrem- 
 ity of the occipital lobe. These divisions of the parieto-oc- 
 cipital fissure inclose a wedge shaped bunch of convolutions, 
 called the cuneus, which is the center of sight memories. 
 The convolutions seen upon this surface from behind for- 
 ward are: the inner margin of the lingualis, the cuneus, quad- 
 ratus, paracentral, marginal and gyrus fornicatus. 
 
 The intrafissural portion of the internal surface of 
 the hemisphere is bounded in front by the rounded surface of 
 the cordon, and from below backward, the ungual and hippo- 
 campal convolutions which are continued above and in front 
 of the corpus callosum by the gyrus fornicatus, which ter- 
 minates at the cordon in front. The surface included within 
 these boundries is filled up by sections of the corpus callosum, 
 fornix, septum lucidum, anterior, middle and posterior com- 
 missures of the third ventricle, lamina cinerea, optic commis- 
 sure, tuber cinereum and infudibulum, corpora albicantia, 
 
THE CEREBRAL HEMISPHERE. 
 
 Ill 
 
 raphe of the crua cerebri, the decussation of the processes, the 
 iter, corpora quadrigemina, and pineal body. It contains the 
 outer wall of the third ventricle, formed by the inner surface 
 of the thalamus opticus; and, extending from the splenium, 
 beneath the corpus callosum and fornix, to the anterior pillars 
 of the fornix in front, is the fissure of Bichat, the anterior 
 extremity of which is the foramen of Monro. 
 
 If the above parts are removed, and also the crus 
 cerebri, there is seen a large oval opening, leading into the 
 center of the hemisphere, which is the aperculum, or hilus of 
 the hemispherical ganglion. The grey matter of the gan- 
 glion terminates at the margin of the aperculum, and is 
 plainly seen at its lower part, where it is called the fascia 
 dentata. Internal to its upper margin is a tract of longi- 
 tudinal fibres, called the superior longitudinal, or commissure 
 of the gyrus. The cordon is seen to be composed of hori- 
 zontal layers of longitudinal fibres, and about half an inch 
 above its lower surface is a groove, seen in figure 17, which 
 is the bed of the anterior commissure of the third ventricle. 
 Attached to the apex of the ungual convolution are the 
 lower extremities of the corpus fimbriatum and the ta3nia 
 semicircularis, between which is seen the lower extremity of 
 the fissure of Bichat leading to the middle cornu of the lat- 
 eral ventricle. 
 
 The convolutions of the hemisphere which compose the 
 hemispherical ganglion can be recollected in the following 
 order: external, internal, and posterior orbital; insula; first, 
 second, and third f I'ontal; anterior, and posterior central; first, 
 second, and third parietal; first, second, and third occipital; 
 first, second, and third temporal; fusiformis; lingualis; ungual, 
 hippocampal, and gyrus fornicatus; cuneus, quadratus, para- 
 central and marginal. 
 
 Ape 
 
 Lower extremities 
 of the corpus fim- 
 briatum, taenia 
 
 ganglia 
 
112 ARCHITECTURE OF THE BRAIN. 
 
 Figure 16 is a representation of tlie external surface of a 
 hemisphere and the convolutions and fissures upon it. The 
 principal fissures are: (1) the fissure of Sylvius, com- 
 mencing below at the junction of the anterior and middle third 
 of the lower border, and extending upward and backward, ter. 
 minates in the middle of the parietal eminence, and a short 
 anterior arm is directed upward and forward into the frontal 
 lobe; and (2) the fissure of Rolando, commencing below about 
 the middle of the posterior arm of the fissure of Sylvius, 
 extends upward and backward to the vertex, dividing 
 the upper portion of the of the hemisphere into anterior 
 and posterior halves, hence this fissure is often called the 
 central fissure. The convolutions upon tliis surface are: 
 orbital, frontal, central, parietal, occipital and temporal. 
 The orbital convolutions are: external, posterior and in- 
 ternal — seen in figurq 2. The first frontal convolution 
 forms the outer surface of the marginal, convolution (figure 
 17), joins the orbital below, and the upper extremity of the 
 anterior central above. The second frontal has two portions; 
 the upper portion joins the middle part of the anterior central, 
 and the lower portion joins the posterior part of the third 
 frontal. The third frontal surrounds the anterior arm of the 
 fissure of Sylvius. The anterior central convolution is con- 
 tinuous with the marginal above and tlie insula below. It 
 will be seen that these convolutions form arches, which 
 through the orbital and and insular convolutions are connected 
 with the cordon (figure 17). The posterior central is con- 
 nected with the insula below, dna the quadratus above, and 
 behind with the parietal lobes. This system includes the 
 first temporal, parietal convolutions, posterior central, quad- 
 ratus, gyrus and hippocampal convolutions, completing arches 
 from the cordon in front. Of the remaining convolutions, 
 they are seen to join the lower temporal and hippocampal 
 convolution at angles, and are continued by them to the cor- 
 don. It will be observed that this arrangement of the con- 
 volutions of the hemisphere is admirably adapted to the 
 passage of longitudinal fibres from every part of the surface 
 of the brain to the frontal lobes, which are the seat of the 
 intellect and judgment. 
 
Fiuuro 1(5. 
 
114 ARCHITECTURE OF THE BRAIN. 
 
 Figure 17 shows the internal surface of the hemispherical 
 ganglion and the convolutions of which it is composed. Its 
 interior is exposed by the removal of the corpus callosum, 
 fornix, septum lucidum, basal ganglia, and the crus cerebri; 
 parts of which fill up the hilus or aperculum of the gan- 
 glion. There are two principal fissures upon this surface: 
 (1) the callosomarginal, beginning at the cordon below, and, 
 arching above the gyrus fornicatus, terminates upon the 
 margin of the great longitudinal fissure between the para- 
 central lobule and the quadratus, a little behind the upper 
 extremity of the fissure of Rolando; (2) the parieto-occipital 
 fissure commences upon the lower surface of the hemisphere 
 external to the hippocampal cc>n volution, and passing upward 
 and backward above the internal margin of the hemisphere 
 divides into two arms which enclose the cuneus. The an- 
 terior arm terminates in the margin of the longitudinal fissure 
 at a point beneath the superior angle of the occipital bone, 
 the crown; the posterior arm passes backward to the extrem- 
 ity of the occipital lobe, and is called the calcarine fissure. 
 The convolutions and their boundaries can be seen upon the 
 figure, and also the connections by which they are continued 
 to the cordon. The grey matter of the hemisphere terminates 
 within the margin of the aperculum, and, being distinctly seen 
 below is called the fascia dentata. Within the upper 
 margin of the aperculum is a large tract of longitudinal 
 fibres, extending from the cordon to the hippocampal convo- 
 lution, which is the superior longitudinal, or commissure of 
 the gyrus. The cordon is a large collection of longitudinal 
 fibres, disposed in horizontal layers, underlying the anterior 
 portion of the internal capsule and basal ganglia. Its under 
 surface is rounded and exposed on the base of the brain at 
 the anterior perforated space. It is perforated by large ves- 
 sels which supply the basal ganglia. The anterior commis- 
 sure of the third ventricle passes through it in a lateral direc- 
 tion, and its bed, uncovered, is seen in the figure. The 
 ungual convolution is seen turning backward behind the cor- 
 don, and, attached to its apex are the ttenia semicircularis and 
 corpus fimbriatum, between which is the lower extremity of 
 the fissure of Bichat entering the middle cornu of the lateral 
 ventricle from the under surface of the brain. The parts 
 which fill up the aperculum are seen in figure 26. The upper 
 part of the aperculum is interhemispherical; the lower por- 
 tion transmits the eras cerebri, and is part of the hilus of the 
 cerebrum. 
 
Figure 17. 
 
116 ABCHITECTURE OF THE BHAIN. 
 
 Figure 18. The insula is exposed by the removal of the 
 convolutions forming the margins of the fissure of Sylvius. 
 The convolutions removed are called its operculum (cover), and 
 must not be confounded with the aperculum or hilus of the 
 hemispherical ganglion (figure 17). 
 
 The insula, or island of Kiel, is composed of six or seven 
 small convolutions, which are continuous above and below 
 with those of the margins of the Assure of Sylvius. The 
 anterior extremities of the convolutions forming the 
 insula are all directed toward the cordon, which is at the bot- 
 tom of the fissure of Sylvius and occupies the anterior per- 
 forated space (figure 17). Above ihe insula is an arch, called 
 the vault, composed of superimposed horizontal layers of 
 fibres, derived from the corpus callosum and the internal cap- 
 sule. This disposition of the fibres, derived from these 
 bodies, permits the passage of longitudinal fibres between 
 them in their passage outward to the convolutions of the sur- 
 face. The same arrangement of fibres from these bodies is 
 seen below the insula, between which the fibres of the exter- 
 nal longitudinal commissure are interposed in their passage 
 from the posterior to the anterior lobes of the hemisphere. 
 Behind the insula are fibres from the thalamus passing back- 
 ward between the plates or layers of the internal capsule. 
 The internal capsule encloses the insula, which is the outer- 
 most part that fills up the funnel shaped concavity enclosed 
 by the capsule. Beneath the convolutions of the hemis- 
 phere is the internuncial layer of short fibres, which extend 
 between adjacent convolutions. 
 
Figure 18. 
 
118 AECHITECTURE OF THE BRAIN. 
 
 Figure 19. Upon the removal of the insula and the sub- 
 convolutional white layer which subtends its grey substance, 
 a broad and thin layer of grey matter is uncovered, called the 
 claustrum, which is difficult to represent in a lateral dissec- 
 tion, but is to be seen in a vertical section, (see vertical sec- 
 tions from figures 10 to 18). This layer of grey matter ia 
 thicker below than above, and covers the external surface of the 
 external capsule, with which it is in immediate relation. This 
 layer having been removed, the dissection here represented 
 shows the external capsule to be composed of fibres radiating 
 upward from beneath the external longitudinal commissure. 
 This layer of fibres is very thin immediately above the com- 
 missure and thick beneath the vault. Its fibres are derived 
 from the outer surface of the lenticular nucleus, and pass 
 upward to unite with the under surface of the fibres of the 
 vault, into which they are lost. The external longitudinal 
 commissure is distinctly seen to form a part of the cordon and 
 to enter the anterior part of the internal capsule in front of the 
 lenticular body. Its posterior extremity intermingles with the 
 posterior fibres of the corpus callosum and internal capsule, 
 and with them is distributed to the posterior convolutions of 
 the hemisphere. 
 
Figure 19. 
 
120 AKCPIITECTDEE OF THE BRAHST. 
 
 Figure 20. In this dissection the outer fibres of the 
 external capsule are removed to expose the external division of 
 the lenticular body (putamen). A small fragment of the 
 external capsule is seen above the external longitudinal com- 
 missure, and the deeper portion of it is seen above the ex- 
 posed portion of the lenticular nucleus. These latter fibres 
 pass directly upward from the surface of the nucleus to enter 
 the vault. 
 
 In front of the lenticular body, the external longitudinal 
 commissure joins with the anterior portion of the internal 
 capsule; and behind, its fibres interlace with the posterior and 
 inferior radiation of the capsule. Between the posterior part 
 of the lenticular nucleus and the genu of the internal capsule, 
 the posterior fibres from the thalamus emerge to pass back- 
 wards to the occipital lobes. These fibres from the thalamus 
 contain the optic radiation to the cuneus and the posterior 
 convolutions of the hemisphere. The radiation of the fibres 
 derived from the internal capsule and corpus callosum, form- 
 ing the vault, surrounds the lenticular nucleus, except a space 
 opposite to the fissure of Sylvius, which is occupied by the 
 longitudinal commissure and cordon. 
 
Figure 20. 
 
122 AKCHITECTDRE OF THE BRAIN. 
 
 Figure 21. The lenticular nucleus and upper portion of 
 the crusta fibres of the internal capsule have been removed, 
 exposing the anterior and posterior distribution of fibres from 
 the thalamus. The fillet is seen to emerge from internal to 
 the crusta, and to pass forward to join the anterior distribu- 
 tion of fibres from the tlialamus. The external longitudinal 
 commissure is fully exposed, and is seen to unite with the fillet 
 fibres in front after forming the mass of fibres which consti- 
 tute the cordon. The anterior commissure of the third ven- 
 tricle passes obliquely outward and backward, across the de- 
 pression which lodges the lenticular body, to reach the outer 
 extremity of the inferior ramus, or temporal distribution, of 
 the internal capsule. 
 
Figure 21. 
 
124 ARCHITBCTUKE OF THE BRAIN. 
 
 Figure 22. The external longitudinal commissure has 
 been removed. The anterior commissure of the third ven- 
 tricle is fully exposed. Behind it are the divided ends of the 
 crusta and the fillet. Above is seen a portion of the external 
 surface of the caudate nucleus, from which the internal cap- 
 sule has been removed. The thalamus consists of concentric 
 laminae, between which are layers of grey matter. At the 
 bottom of the cavity, made by washing out the grey matter 
 of the thalamus, is seen the red nucleus of the tegmentum. 
 The fibres of the corpus callosum are distinctly seen to decus- 
 sate with those of the internal capsule. The laminae of 
 which each is composed overlie each other, and break off in 
 pointed plates, as seen in the posterior part of the figure. 
 
Figure 22. 
 
126 AROHITECTUKE OF THE BRAIN. 
 
 Figure 23 — Is an intrahemispherical view of the internal 
 surface of a hemisphere, in which the fissures are seen as pro- 
 jections upon the surface, and the convolutions as depressions. 
 The internal capsular fibres are entirely removed, and the 
 laminae of the corpus callosum are seen projecting from the 
 surface. Above the corpus callosum are the longitudinal 
 fibres of the gyrus fornicatus, called the superior longitudinal 
 commissure, which is seen from above in figure 3. Beneath 
 the corpus callosum is a portion of the lining membrane of 
 the lateral ventricle which covers the ventricular surface of 
 the caudate nucleus. The ventricle is opened behind the 
 thalamus, exposing a portion of the fornix and the hippo- 
 campi. The concentric layers which compose the thalamus 
 are well seen in the figure, as well as the relative positions of 
 this body, the fillet, crusta and the anterior commissure of 
 the third ventricle. 
 

 Figure 23. 
 
CEREBRAL LOCALIZATION. 
 
 The observation of the results of disease and accidents 
 in man, and the experiments of Ferrier, Horsley and others, 
 upon the brains of the lower animals, have established the 
 fact, that certain parts (>f the hemispherical ganglion are en- 
 dowed with special functions. The areas that receive the 
 impressions from certain sensory nerves, and that control the 
 movements of certain parts of the body, are definitely 
 mapped upon the surface of the brain, and experience has 
 demonstrated that these discoveries are worthy of confidence. 
 
 It is not to be supposed, however, that a science which 
 is so recent in its origin has reached a stage of perfection 
 which is absolutely reliable, but sufficient is already proven 
 to wan-ant the belief that more definite knowledge is at hand. 
 
 It has long been known that injuries and inflammation 
 involving the central part of the surface of the brain are 
 productive of convulsions; that an injury to the third frontal 
 convolution of the left side, (Broca's convolution,) destroys 
 the ability to speak; that disturbances of the intellect occur 
 in afi^ections of the anterior lobes of the brain; and that 
 memory suffers from disease of the occipital lobes. These 
 general observations are confirmed by more recent and 
 careful investigation. The areas devoted to the general 
 functions of the mind, viz.: judgment, memory, and motion, 
 are now more definitely described, and subdivided into parts 
 Motor area of the to whlch speclfic functious arc attributed. The motor area 
 is situated about the fissure of Rolando, viz. : in the posterior 
 portion of the frontal convolutions, the anterior and posterior 
 central convolutions, and in the superior parietal lobule. 
 This area is divided into smaller portions, which are asso- 
 ciated with certain muscular movements, as indicated upon Fig. 
 
 brain. 
 
CEREBRAL LOCALIZATION. 129 
 
 24. Common sensation and muscular sense are situated above 
 and behind the posterior extremity of the fissures of Sylvius; 
 hearing and the memory of words are located in the upper 
 temporal convolutions; smell and taste, in the apex and 
 under surface of the temporal lobe; and vision and the sight 
 memory of words, in the occipital lobes and the cuneus. 
 For more exact information the reader is referred to the 
 works of Ferrier and Horsley. 
 
 The above observations are intended to direct the atten- 
 tion to the importance of the study of the anatomical rela- 
 tions between the surface of the brain and the surface of the 
 head, and also of the deeper parts of the brain to its ex- 
 ternal surface. This is the more important, because the walls 
 of the cavity which contain the brain are rigid, requiring ihe 
 surgeon to direct his operations upon this organ as near the 
 seat of the lesion as possible. We have seen that the struc- 
 tures within the brain are more or less important for the 
 immediate support of life and mental integrity, therefore, 
 it is quite essential that the surgeon should know the sit- 
 uation and direction to the parts lying beneath the point ex- 
 posed by the trephine, and the safe direction in which he 
 may venture to puncture a ventricle, open an abcess, or use 
 the knife in the removal of a tumor. The cranial cavity is 
 a very important surgical space, and the invader should be 
 better acquainted with its anatomy than with that of any other 
 region, on account of the important functions of its contents. 
 It is not sui'prising, in the present state'of our knowledge of 
 the anatomical relations of the parts of the brain, to learn 
 of recoveries after great violence has been done to this deli- 
 cate organ, and at other times, that death has resulted from 
 a mere puncture. 
 
 For certain reasons, exact localization is an impossibility, 
 though practically this may be obtained within approximate 
 limits. The brain may be exposed, if not in the precise 
 locality sought after, yet near to the situation, which may be 
 recognized by appearance or electrical test. It is of little 
 consequence that a larger portion of the skull is afterward 
 
 Area of 
 
 CO 
 
 mmon 
 
 s 
 
 
 
 land 
 
 ■ 
 
 nuscu 
 
 lai 
 
 ■ sense. 
 
 He 
 
 taring 
 
 rie 
 
 id wore 
 
 So 
 
 lellar 
 
 id 
 
 taste, 
 
 Vh 
 
 3iona 
 
 nd 
 
 sight 
 
130 
 
 ARCHITECTURE OF THE BRAIN. 
 
 System of localiz 
 tion presented. 
 
 Prominent points 
 and lines upon 
 the skull. 
 
 removed, in order to reach the desired point. Experience in 
 the examination of different skulls and heads is of great 
 assistance in determining the situation of the prominent 
 fissures and convolutions beneath the surface, enabling the 
 surgeon to place his finger over them without effort, or the 
 assistance of instruments. The variations in different subjects 
 are due: first, to the fact before mentioned, that no two brains 
 are identically marked, nor are the opposite sides of the 
 same brain symmetrical; second, there is frequently a dispro- 
 portion between the cerebrum and the cerebellum; when 
 the latter organ is large and deep in its vertical diameter, 
 it has the effect of elevating the posterior part of the 
 cerebrum and the vertex of the skull, thereby deranging 
 the lines drawn upon the head as guides to the parts beneath; 
 third, what is true of the brain may also be said of the skull, 
 that parts which are prominent in some skulls are almost 
 wanting in others; for example, the parietal and frontal 
 eminences, the prominence of the occiput, and the nasion 
 may be obscure, and the superior angles of the frontal and 
 occipital bones, in some instances displaced. Experience 
 and judgment is as essential to the aspirant for success 
 in cerebral surgery, as it is to the pelvic surgeon, who 
 also finds in the pelvic region variations which must influence 
 his judgment in particular cases. 
 
 In devising, therefore, any system of cerebral localization, 
 it is requisite that we should adopt that method which affords 
 the best means under the circumstances of selecting the most 
 reliable guides. In the method of localization here presented, 
 the instrument required is a common string, which is always 
 at hand. The location of a few prominent points and lines, 
 which are easily found and remembered, is all that is neces- 
 sary. These are, (see figure 282): the nasion, or root of the 
 nose; the occiput; the vertex, which is midway between the 
 latter two points; the prominences of the angles of the frontal 
 and the occipital bones, situated in the median line of 
 the head; the former about one inch and a half in front of 
 the vertex, and the latter about midway between the vertex 
 
gitudi- 
 
 Lobes forming the 
 
 CEREBRAL LOCALIZATION. 131 
 
 and the occiput. Other points are: the external angular pro- 
 cess of the frontal bone, outer canthus of the eye, inferior 
 angle of the malar bone, external auditory meatus, and the 
 mastoid process of the temporal bone. 
 
 Beneath the median line of the skull, from the nasion to 
 the occiput, is the superior longitudinal sinus, and the longi- Position ot th 
 tudinal fissure separating the hemispheres of the cerebrum 
 The calloso-marginal fissure emerges from the median fissure '^^dlZllZlTJil 
 a little behind the vertex, and the anterior arm of the parieto- j''','_''„^g""'' ^"^ 
 occipital fissure reaches the surface just above the superior 
 angle of the occipital bone. The upper margins of the lobes 
 of the internal surfaces of the hemispheres occupy spaces 
 along the median line: the lingualis and cuneus from the occi- 
 put to the upper angle of the occipital bone, the quadratus 
 from the occipital angle nearly to the vertex, the paracentral 
 lobule from the vertex to the angle of the frontal bone, and 
 the marginal convolution from this point to the nasion. 
 
 A line drawn from the outer canthus to the center of the 
 parietal eminence covers the -fissure of Sylvius, and if contin- 
 ued this line passes through the crown to the opposite auditory 
 meatus; another line drawn from the inferior angle of the 
 malar bone to the vertex indicates the position of the fissure 
 of Rolando. 
 
 The fissure of Sylvius reaches the outer surface of the 
 hemisphere at the intersection of these lines, and divides into 
 a short anterior arm whicb is directed upward and forward 
 into the third frontal convolution, and a long or posterior 
 arm which extends from the point of division of the fissure, 
 backward and upward, to the middle of the parietal eminence. 
 The center of the parietal eminence is at the intersection of a 
 line from the vei'tex to the auditory meatus, with the line 
 marking the fissure of Sylvius. 
 
 The fissure of Rolando begins below, about the middle of 
 the posterior arm of the fissure of Sylvius, and, extending roi 
 directly upward for a short distance, reaches the before men- 
 tioned line from the inferior angle of the malar bone to the 
 vertex, under the upper portion of which it lies. The anter- 
 
 ines 
 
 indicating 
 
 tlie 
 
 fissures ot 
 
 Syl' 
 
 dus and 
 
 Rol 
 
 ando. 
 
 Fig. 
 
 235^. 
 
 ituai 
 
 tionof the 
 
 lissi 
 
 ire of Sylvius. 
 
 Of the fissur 
 
132 ARCHITECTURE OF THE BRAIN. 
 
 Central convolu 
 
 Parietal lob^ 
 
 ior and posterior central convolutions bound the margins of 
 the fissure of Rolando. The frontal convolutions lie beneath 
 the frontal bone; the first occupying the space between the 
 
 ■°'"- frontal eminence and the median line; the third, surrounding 
 the anterior arm of the fissure of Sylvius, lies in the tem- 
 poral fossa, behind the external angular process. The inter- 
 vening space is occupied by the two divisions of the second 
 
 Mvoiu- frontal convolution. The temporal convolutions lie beneath 
 the fissare of Sylvius and extend upward and backward par- 
 allel to it. The supra marginal, or second parietal convolu- 
 tion, surrounds the posterior extremity of tlie Sylvian fissure, 
 and occupies the region of the parietal eminence. The fir.-t 
 
 ■s. parietal lobule is above the parietal eminence, and is bounded 
 
 above by the margin of the lobus quadratus. The third parietal 
 convolution, or gyrus angularis, is behind and slightly above 
 the parietal eminence, in front of the lambdoid suture. Tlie 
 occipital convolutions are covered by the occipital bone, and 
 border upon the cuneus and lingualis, with which they are 
 connected. 
 
 An important point to be located is situated above and 
 behind the auditory meatus. It is indicated by the inter- 
 section of two lines, one drawn from the auditory meatus to 
 the superior occipital angle, and the other from the external 
 
 "'^ angular process of the frontal bone to the occiput. The point 
 border of iiitersectlon marks the outer extremity of the lateral siuus, 
 and also the outer extremity of the superior border of the 
 petrous portion of the temporal bone, which divides the pos- 
 terior from the middle fossa of the skull. The lateral sinus 
 is directed backward from this point to the occiput, and is 
 usually lower down upon the left than the right side of the 
 head, on account of the larger size of the left hemisphere of 
 the cerebrum, and the smaller size of the left hemisphere of 
 the cerebellum. 
 
 Figure 24 shows the situation of the various sensory and 
 motor centers of the convolutions, according to Horsley; and 
 figure 25 the same after Ferrier. By a comparison of these 
 figures, it will be observed that there is an agreement which 
 
 ; pet; 
 m of the 
 )ral bone, 
 
CEREBRAL LOCALIZATION. 
 
 133 
 
 is corroborative. Figures 25 and 26 are marked by vertical 
 lines into thirty-six sections, which are one-sixth of an inch 
 apart, and numbered to correspond with those of the figures 
 that follow aftei'. 
 
 By the use of the topographical sections, it will be 
 easy to study the relations of the deeper parts to the surface 
 of the braio; and by a comparison of successive sections, the 
 dee pel' parts may be traced in their relations to each other, 
 and compared with the dissections previously studied The 
 directiou in which a trocar may be thrust with safety, and 
 with the least danger of injury to important structures, can be 
 determined at a glance. An examination of these sections 
 creates a suprise that, in so short a distance as one-sixth of an 
 inch, tlie configuration of the successive sections present so 
 great a difference in appearance. 
 
 The location of the 
 deeper parts of 
 the brain by the 
 aid of topOKraph- 
 ical sections. 
 
Fiffiire 28^. 
 
Figure 24. 
 
TOPOrmAPHICAL SECTIONS OF THE BRAIN. 
 
 External Surface of the Hemisphere. 
 
 LOBES. 
 
 Fl F2 F3 — Frontal. AC and PC — Anterior and posterior central. Tl T2 T3 — Tem- 
 poral. PI P2 P3— Parietal. P2 — Often called supraraarginal. P3— Gyrus 
 angularii. 01 02 03— Occipital. 
 
 FISSURES. 
 The fissure of Sylvius is situated above and along the first temporal lobe, and is 
 indicated by a line drawn on the surface of the head from the outer canthus of the 
 eye to the parietal eminence, and if continued the line would pass through the crown to 
 the opposite auditory meatus. The fissure of Rolando is between the lobes AC and 
 PC, and is indicated by a line drawn from the lower angle of the malar bone to the 
 vertex. To locate the lobes and fissures along the longitudinal fissure; the cuneu-S 
 occupies the space between the occiput and the crown, where the fissure PO reaches 
 the surface; the quadrate lobe extends from the crown to the vertex, where the fissure 
 CM reaches the surface; the paracentral lobule extends from the vertex to the superior 
 angle of the frontal bone; the frontal bone covers the marginal convolution. These 
 directions though not exact are sufiicient for practical purposes and are quite as relia- 
 ble as any of the expensive contrivances in use for locating these parts. The outer 
 portion of the Great Transverse fissure is between the occipital lobes and the cere- 
 bellum. 
 
 PSYCHOMOTOR CENTERS. (From Ferrier.) 
 
 1. Advance ofthe opposite hind limb as in walking 
 
 2, 3, 4. Complex movements of the opposite leg and arm and of the trunk, as in swim- 
 
 ming. 
 a, b, c, d. Individual and combined movements of the fingers and wrist of the 
 opposite hand. Prehensile movements. 
 
 5. Extension forward of the opposite arm and hand. 
 
 6. Supination and flexion of the opposite forearm. 
 
 7. Retractio;; and elevation of the opposite angle of the mouth by means of the 
 zygomatic muscles. 
 
 8. Elevation of the alae nasi and upper lip with depression of the lower lip on the 
 opposite side. 
 
 9. 10. Opening of the mouth with (9) protrusion, and (lOj retraction of the tongue. 
 
 Region of Aphasia. 
 
 11. Retraction of the opposite angle of the mouth, the head turned slightly to one 
 side. 
 
 12. Eyes open widely, pupils dilating, and the head and eyes turning towards the 
 opposite side. 
 
 13. 14. The eyes moving towards the opposite side with an upward (13), or downward 
 
 (14) deviation. Pupils generally contracting. (Center of vision ) 
 15. Pricking up of the opposite ear. head and eyes turning to the opposite side, and 
 pupils dilating largely. (Center of hearing.) 
 136 
 
Fisrure 25, 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 (These sectios are cut sis to the inch, and the plates are made from photograph of the sections.) 
 
 Median Section along tlie Great Longitudinal Fissure. 
 
 LOBES. 
 
 L — LiDgualis. C— Cuneus. Q— Quadratus. QF— Gyrus fornicatus. PC — Para- 
 central. MM — Marginal. 
 
 FISSURES. 
 
 The fissure of Bichat, or the Great Transvers fissure, is between the lingual lobe 
 and the cerebellum. The Calcarine fissure is between L and C. The Parieto-occip- 
 ital fissure is between C and Q The Calloso-marginal fissure is bounded by the lobes 
 Q and GF below, and PC and MM above. The fissure called the Ventricle of the 
 Corpus Callosum is between GF and CC. 
 
 COMMISSURES, ETC. 
 
 CC— Corpus callosum. F — Fornix. SL- Septum lucidum. Beneath F is the 
 intraventricular portion of the Great Transverse fissure, through which passes the 
 velum interpositum from the third to the lateral ventricle, its anterior extremity is 
 called the Foramen of Monro. AC — Anterior commissure. MC — Middle commis- 
 sure. P -Pineal gland, its anterior pillars extending forwards below the fornix. In 
 front of and beneath P, is the posterior commissure. TN— Corpora quadrigemina 
 — T is on the testes, and N on the nates. Beneath T and N is the iter. CE -Cere- 
 bellum. Between CE and T is the valve of Vieussens, beneath which is the cavity of 
 the fourth ventricle. Above and below the valve are the superior and inferior 
 vermiform processes. R -Restiform body, beneath which is the central canal of the 
 cord DP — Decussation anterior pyramids N— Pons Varolii. FT — Fillet or lem- 
 niscus. Between FT and the fourth ventricle is the fasciculi teretes. PT — Decussa- 
 tion of the processes testes. RN— Cms cerebri, the letters are over the red nucleus. 
 3 —Third nerve. CA- Corpora albicantia. I — Infundibulum and tuber cinereum. 
 O — Optic commissure Between O and AC is the lamina cinerea, in front of which 
 is the anterior pillar of the the corpus callosum. 
 
1Q» 
 
 Figure 26. 
 
140 
 
 ARCHITECTURE OF THE BRAIN. 
 
 ■'X 
 
 No. 1. 
 
 "%yf> 
 
 No. 2. 
 
 M and M — Marginal conv. 
 f 1 fS fS — Frontal convolu- 
 tions. 
 '0 — Orbital convolution. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 141 
 
 No. 3. 
 
 No. 4. 
 
 M and M — Marginal conv. 
 Fi F^ r» —Frontal convolu- 
 tions. 
 — Orbital convolution. 
 
142 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 
 
 Gf r — GjTus fornicatus. 
 M and M — Marginal conv. 
 f 1 ^2 fS — Frontal convolu- 
 tions. 
 — Orbital convolution. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 143 
 
 No. 6. 
 
 Of F — Gyrus fornicatus. 
 
 M and M — Marginal conv. 
 fifsps — Frontal convolu- 
 tions. 
 — Orbital convolution. 
 
144 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 7. 
 
 C C — Corpus callosum. 
 Of F — Gyrus fornicatus. 
 M and M — Marginal conv. 
 j'lj'aj'S — Frontal convolu- 
 tions. 
 — Orbital convolution. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 145 
 
 No. 8. 
 
 CC -Corpus callosum. 
 G F — Gyrus fornicatus. 
 M M — Marginal convolution. 
 f 1 Y^ F* — Frontal convolu- 
 tions. 
 
 — Orbital convolution. 
 V — Anterior cornu of lateral 
 ventricle. 
 
146 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 9. 
 
 CC^ Corpus callosiim. 
 Gr F — Gyrus fornicatus. 
 M M — Marginal convolution. 
 pi p2 j,-3 — Frontal convolu- 
 tion. 
 — Orbital convolution. 
 
 Y — Anterior cornu of lateral 
 
 ventricle. 
 N C — Nucleus caudatus. 
 C L — Claustrum. 
 In — Insula, or island of Riel. 
 S' — Fissure of Sylvius. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 147 
 
 No. 10. 
 
 CC and ec — Corpus callosum. 
 G F — Gyrus fornicatus. 
 M and M — Marginal conv. 
 pi F2 J13 _Frontal convolu- 
 tions. 
 — Orbital convolution. 
 
 V — Lateral ventricle. 
 
 N C — Nucleus caudatus. 
 
 I C Internal capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or island of Riel. 
 
 S and S— Fissure of Sylvius. 
 
148 
 
 ARCHITECTURE OF THE BRAIN 
 
 No. 11. 
 
 CC and (•( — Corpus callosum. 
 
 a P — Gyrus fornicatus. 
 
 M — Marginal convolution. 
 
 pi F^ F* — Frontal convolu- 
 tions. 
 
 T^ — First temporal convolu- 
 tion. 
 
 — Orbital convolution. 
 
 V — Lateral ventricle. 
 
 N C — Caudate nucleus. 
 
 I C — Internal capsule. 
 
 N L — Lenticular nucleus. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or island of Riel. 
 
 S and S — Fissure of Sylvius. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 149 
 
 No. 12. 
 
 CC and CC — Corpus callosum. 
 Gr F — Gyrus fornicatus. 
 M — Marginal convolution, 
 f 1 f 2 j"3 — Frontal convolu- 
 tions. 
 A F — Ascending frontal conv. 
 rpi ffi fpa — Temporal convs. 
 — Orbital convolution. 
 
 V — Lateral ventricle. 
 
 N C — Nucleus caudatus. 
 
 I C — Internal capsule. 
 
 N L — Nucleus lenticularis. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or island of Riel. 
 
 S and S— -Fissure of Sylvius. 
 
150 
 
 ARCHITECTURE OF THE BRAIN. | 
 
 No, 13. 
 
 C C — Corpus callosum. 
 G F — Gyrus fornicatus. 
 CM — Calloso-marginal fissure 
 M — Marginal convolution. 
 pi f 3 ps Frontal convs. 
 A F — Ascending frontal conv. 
 K- — Fissure of Rolando. 
 rpi 7-2 rj-s —Temporal convs 
 — Optic nerve. 
 S P- Substantia perforata 
 anterior. 
 
 V — Lateral ventricle. 
 
 N C — Nucleus caudatus. 
 
 I C — Internal capsule. 
 
 N L — Nucleus lenticularis. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or Island of Riel. 
 
 S and S — Fissure of Sylvius. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 151 
 
 No. 14. 
 
 C C — Corpus callosum. 
 
 G F — Gyrus fornicatus. 
 
 C M — Calloso-marginal fissure 
 
 M — -Marginal convolution. 
 
 fi pa ps — Frontal convs. 
 
 A F — Ascending frontal or 
 
 central convolution. 
 R — Fissure of Rolando. 
 rpi X^ T* —Temporal convs. 
 F M — Fusiform convolution 
 H — Hippocampal conv. 
 g P — Substantia perforata. 
 
 — Optic nerve. 
 
 L C — Lamina cinerea. 
 
 A C — Anterior commissure. 
 
 F — Anterior pillar fornix. 
 
 V — Lateral ventricle. 
 
 N C — Caudate nucleus. 
 
 I C— -Internal capsule. 
 
 N L — Lenticular nucleus. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or island of Riel. 
 
 S and S— Fissure of Sylvius. 
 
152 
 
 ARCHITEOTURE OF THE BRAIN. 
 
 No. 15. 
 
 C C — Corpus callosum. 
 
 G F — Gyrus fornicatus. 
 
 C M — Calloso-marginal fissure 
 
 M — Marginal convolution. 
 
 pi F^F* — Frontal convs. 
 
 A F — Ascending frontal or 
 
 central convolution. 
 R R — Fissure Rolando. 
 XI T^T"— Temporal convs. 
 F M — Fusiform convolution. 
 H — Hippocampal convolution 
 S P — Substantia perforata. 
 — Optic commissure. 
 Lc — Lamina cinerea. 
 
 F and F — Fornix. 
 
 T* — Third ventricle. 
 
 V — Lateral ventricle. 
 
 N C — Caudate nucleus. 
 
 I C — Internal capsule. 
 
 LN — Lenticular nucleus. 1, 
 2, .3, its three divisions. 
 
 AC — Divided outer extrem- 
 ity of the anterior commis- 
 sure. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula. 
 
 S and S — Fissure Sylvius. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 153 
 
 No. 16. 
 
 C C — Corpus callosum. 
 
 Gr F — Gyrus fornicatus. 
 
 C M — Calloso-marginal fissure 
 
 P — Paracentral lobule. 
 
 pi — First frontal conv. 
 
 A C — Anterior central or as- 
 cending frontal. 
 
 PC — Posterior central or as- 
 cending parietal. 
 
 R — Fissure of Rolando. 
 
 S M — Supramarginal or sec- 
 ond parietal lobule. 
 
 rpi rji-2 rjig — Temporal convs. 
 
 FM — Fusiform convolution. 
 
 H — Hippocampal conv. 
 
 SPP — Substantia perforata 
 
 posterior. 
 — Optic tract. 
 T C — Tuber cinereum. 
 F and F — Fornix. 
 V^ — Third ventricle. 
 Y — Lateral ventricle. 
 N C — Tail of caudate nucleus. 
 T H — Thalamus opticus. 
 IC and IC — Internal capsule. 
 LN ' "' ^ — Lenticular nucleus. 
 X — External capsule. 
 C L — Claustrum. 
 Ill — Insula, or island of Riel. 
 S and S — Fissure of Sylvius. 
 
154 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 17. 
 
 CC — Corpus callosum. 
 
 G F — Gyrus fornicatus. 
 
 CM — Calloso-marginal fissure 
 
 P — Paracentral lobe. 
 
 RandR — Fissure of Rolando. 
 
 AC and PC — Anterior and 
 posterior central convs. 
 
 S M — Supramarginal or sec- 
 ond parietal convolution. 
 
 iji fS fj^s — Temporal convs. 
 
 FM — Fusiform convolution. 
 
 H — Hippocampal conv. 
 
 VM - Middle cornu of lateral 
 vent, and pes hippocampi. 
 
 SPP — Substantia perforata 
 posterior. 
 
 — Optic tract. 
 
 C A — Corpus albicantia. 
 
 T* — Third ventricle. The 
 letter rests upon the grey 
 matter of its wall opposite 
 the middle commissure. 
 
 F — Fornix. 
 
 V — Lateral ventricle. 
 
 N C — Tail of caudate nucleus. 
 
 T H— Thalam.us. 
 
 IC and IC — Internal capsule. 
 
 LN^ 2 3 — Lenticular body; its 
 three divisions. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or island of Riel. 
 
 S and S— Fissure of Sylvius. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 155 
 
 No. 18. 
 
 CI C — Corpus callosum. 
 
 G F- -Gyrus fornicatus. 
 
 C M — Colloso-marginal fissure 
 
 P — Paracentral lobule. 
 
 AC and PC — Anterior and 
 posterior central convs. 
 
 R — Fissure of Rolando. 
 
 S M — Supramarg. conv. 
 
 rpi rj"2 rps — Tempore sphe- 
 noidal, or temporal convs. 
 
 F M — Fusiform convolution. 
 
 H — Hippocampal. The letter 
 rests upon the cornu Am- 
 monis. 
 
 V M— Middle cornu lat. vent. 
 
 — Optic tract. 
 
 S N — Substantia nigra of crus 
 cerebri, and external to SN 
 are the fibres of the crusta 
 passing upward to the in- 
 
 ternal capsule. 
 
 V^--Wall of third ventricle. 
 
 F — Fornix. 
 
 y — Lateral ventricle. 
 
 N C and N C — Tail of caudate 
 bod}'; • the lower NC is ex- 
 ternal to O and is the lower 
 extremity of the tail of the 
 caudate body, situated in 
 the roof of the middle cornu 
 of the lateral ventricle. 
 
 IC and IC — Internal capsule; 
 the lower IC are the fibres 
 of the capsule distributed 
 to the temporal lobes. 
 
 jj jj 12 3 — Lenticular body. 
 
 X — External capsule. 
 
 C L — Claustrum. 
 
 In — Insula, or island of Riel. 
 
 S — Fissure of Sylvius, 
 
156 
 
 ARCHITECTUEE OF THE BRAIlf. 
 
 No. 19. 
 
 C C — Corpus callosum. 
 
 (j F — Gyrus fornicatus. 
 
 C M— Calloso-marginal fissure 
 
 P — Paracentral lobe. 
 
 A C and 'P C — Anterior and 
 posterior central convs. 
 
 R — Fissure of Rolando. 
 
 S M — Supra marginal conv. 
 
 Ti T^ T** —Temporal convs. 
 
 F M — Fusiform lobe. 
 
 H — Hippocampal. 
 
 VM — Middle cornu lateral 
 ventricle. 
 
 — Optic tract. 
 
 SN — Substantia nigra, or lo- 
 cus niger. The crusta is 
 external to SN, and is con- 
 tinuous with IC. 
 
 II N — Red nucleus, running 
 out from which is the fillet. 
 
 ys —Wall of third ventticle. 
 
 F — Fornix. 
 
 Y — Lateral ventricle. 
 
 NC and N€ — Caudate nucleus. 
 
 TF — Thalamus. 
 
 IC, IC, IC — Internal capsule. 
 The row of dark spots be- 
 tween the upper and lower 
 IC is the posterior extrem- 
 ity of the lenticular nucleus. 
 
 In — Insula, or island of Riel. 
 
 S — Fissure of Sylvius. A 
 trace of the claustrum can 
 be seen in this section. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 157 
 
 No. 20. 
 
 CC — Corpus collosum. 
 
 GrF — Gyrus fornicatus. 
 
 C M — Calloso-marginal fissure 
 
 P — Paracentral lobe. 
 
 AC and PC — Anterior and 
 posterior central convs. 
 
 R — Fissure of Rolando. 
 
 P^ — Paracentral lobe. 
 
 S M — Supramarginal conv. 
 
 XI T" T* —Temporal, or tem- 
 pero sphenoidal convs. 
 
 F M — Fusiform. 
 
 H — Hippocampal convolu- 
 tion, or cornu Ammonis, the 
 projection of which into the 
 middle cornu of the lateral 
 ventricle forms the hippo- 
 campus major. 
 
 V M— Middle cornu. 
 
 G G — Corpus geniculata, ex- 
 ternal and internal, which 
 are the termination of the 
 two roots of the optic tract. 
 
 N — Pons Varolii. 
 
 S N — Substantia nigra. 
 
 R N — Red nucleus, which is 
 connected b)' a grey com- 
 missure with another round 
 grey mass above, and inter- 
 nal to the letters TH. 
 
 ys — Third ventricle. 
 
 F — Fornix. 
 
 V — Lateral ventricle. 
 
 NC and NC — Caudate nucleus. 
 
 T H — Thalamus, displaying a 
 peculiar radiation of fibres. 
 
 IC and IC — Internal capsule 
 at its genu. 
 
 S — Fissure of Sylvius. 
 
158 
 
 ARCHITECTURE OF THE BRAIW. 
 
 No. 21. 
 
 C C — Corpus callosum. 
 
 Gr F — Gyrus fornicatus. 
 
 Q — Quadratus or precuneus 
 lobe. 
 
 C M — Calloso-marginal fissure 
 
 P. and AC — Union of para- 
 central and anterior central 
 convolutions. 
 
 R — Fissure of Rolando. 
 
 P C — Poterior central or as- 
 cending parietal conv. 
 
 pi — First parietal lobule. 
 
 P^ and S M — Second parietal 
 lobule or supra marginal 
 convolution. 
 
 rpi rp2 ff s — Temporal convs. 
 
 F M — Fusiform convolution. 
 
 H — Hippocampal lobe. 
 
 Y M — Middle cornu and hip- 
 pocampus major; and direct- 
 ed toward G G is the corpus 
 
 fimbriatum or edge of the 
 fornix, forming the lower 
 boundary of the fissure of 
 Bichat, through which the 
 velum enters the lateral 
 ventricle. 
 
 G G — Corpora geniculata, con- 
 tinuous below with the optic 
 tract and behind with the 
 pulvinar. 
 
 P — Pulvinar. 
 
 N — Pons. 
 
 F T— Fillet tract. 
 
 S N — Substantia nigra. 
 
 P T — Processus testes. 
 
 C P — Posterior commissure. 
 
 F — Fornix. 
 
 V — Lateral ventricle. 
 
 NC and NO — Caudate nucleus. 
 
 I C and IC — Internal capsule. 
 
 S — Fissure Sylvius. 
 
TOPOGRAPHICAL SECTIONS OF THE BEAIN 
 
 1591 
 
 No. 22. 
 
 C C — Corpus callosum. 
 
 GrF — Gyrus fornicatus. 
 
 Q — Lobus quadratus. 
 
 C M — Calloso-marginal fissure 
 
 P and AC — Paracentral and 
 
 ascending frontal. 
 R — Upper end of fissure of 
 
 Rolando. 
 P C — Posterior central conv. 
 pi . — First parietal lobule. 
 p2andS)I — Second parietal 
 
 lobe. 
 rpi rji3 rps — Temporal convs. 
 F M — Fusiform conv. 
 H — Hippocampal conv. at its 
 
 junction with the lingualis 
 
 and gyrus fornicatus. 
 N — Pons Varolii. 
 FT — Fillet or lemniscus. 
 P T — Processus e cerebello ad 
 
 testes at its decussation. 
 
 IT— Iter. 
 
 N A— Nates. 
 
 P — Pineal gland. 
 
 T,v — Lvra. 
 
 P y — Pulvinar, or optic centre 
 
 ot ine tnaiaiuus. 
 TH— Thalamus. 
 F and F — Fornix, winding 
 
 around the posterior part of 
 
 the thalamus. 
 Y — Lateral ventricle. 
 NC and NC— Genu of the tail 
 
 of the caudate nucleus. 
 YJI — Middle cornu of the lat- 
 eral ventricle. 
 I C — Posterior fibres of the 
 
 Internal capsule. 
 L — External longitudinal 
 
 commissure. 
 S — Fissure of Sylvius. 
 
160 
 
 ARCHITECTURE OF THE BRAIK^. 
 
 No. 23. 
 
 C C — Corpus callosum. 
 
 G F — Gyrus fornicatus. 
 
 Q — Lobus quadratus. 
 
 C M — Calloso-marginal fissure 
 
 P — Paracentral lobule. 
 
 R — Fissure of Rolando. 
 
 P C — Ascending parietal or 
 
 posterior central conv. 
 Pi — First parietal lobule. 
 P* — Third parietal lobule or 
 
 gyrus angularis. 
 P- — Second parietal lobule. 
 fji ^[2 fs — Temporal convs. 
 F M — Fusiform lobe. 
 L G — Lobus lingualis. 
 C — Cerebellum. 
 N— Pons. 
 FT — Fillet or lemniscus. 
 
 P T — Processus e cerebello ad 
 testes. 
 
 I T — Iter e tertio ad quartum 
 ventriculum. 
 
 T — Testes. 
 
 VP — Posterior cornu of the 
 lateral ventricle. 
 
 Y 31 — Middle cornu of the 
 lateral ventricle. 
 
 IC Posterior distribution of 
 fibres of the internal cap- 
 sule. 
 
 L — External longitudinal 
 commissure, separated from 
 the sub-convolutional la}'er 
 of the corona radiata by a 
 delicate arched white line. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 161 
 
 C C — Corpus callosum. 
 
 GrF and GF — Gyrus fornicatus 
 
 Q — Lobus quadratus or pre- 
 cuneus. 
 
 C 31 — Calloso-marginal fissure 
 
 P and PC — Junction of para- 
 central and post, central 
 convolutions. 
 
 Pi ■ — First parietal lobe. 
 
 P^ — Gj'rus angularis. 
 
 rj\2 ff 3 , — Temporal convs. 
 
 F M— Fusiform lobe. 
 
 L (t — Lingualis. 
 
 YP and TM— Junction of the 
 posterior with the middle 
 cornu of the lateral ventricle 
 
 L — Ext. longitudinal comm. 
 
 I C — Internal capsule. 
 
 P T — Processes testes. 
 
 N — Lateral fibres of pons. 
 
 R — Restiform fibres of me- 
 dulla oblongata. 
 FT— Fillet. 
 
 P R — Anterior pyramids of 
 the medulla. 
 
 The composition of the 
 corona radiata is well seen in 
 this plate. The fibres of the 
 corpus callosum are internal 
 to the ventricle; the decussa- 
 tion between its fibres and the 
 internal capsule is above, 
 while the outer wall of the 
 ventricle is formed by the in- 
 ternal capsule, separated from 
 L by a dark line. External 
 to L is the sub-convolutional 
 white fibres, or internuncial 
 layer of the corona radiata. 
 
162 
 
 ARCHITECTURE OF THE BRAHf. 
 
 No. 25. 
 
 L — External longitudinal 
 commissure. 
 
 V P — Posterior cornu. Be- 
 tween L and V P are fibres 
 of the internal capsule di- 
 rected backward to the 
 cuneus and occipital lobtf, 
 containing optic fibres. 
 
 C C — Posterior fibres of the 
 corpus collosum. 
 
 P — Commencement of the 
 parieto-occipital fissure. 
 
 GF and GF— Gyrus fornicatus 
 
 Q — Lobus quadratus. 
 
 C M —Calloso-marginal fissure 
 
 pi —First parietal lobule. 
 
 P^ — Lobus angularis. 
 
 P'^ — Supra-marginal or sec- 
 ond parietal lobule. 
 
 IJ2 rps — Temporal convolu- 
 tions. 
 
 F H — Fusiform convolution. 
 
 L G — Lingualis. 
 
 C — Cerebellum. 
 
 N — Lateral fibres of pons. 
 
 R — Restiform body. 
 
 — Olivary body. 
 
 P R — Anterior pyramid. 
 
 F T— Fillet. 
 
 T — Fasciculus teretes. 
 
 P T — Processes testes and 
 fourth ventricle. The valve 
 of Vieussens forms the roof 
 of the fourth ventricle by 
 uniting the upper part of 
 one processus with the 
 other. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 163 
 
 No. 26. 
 
 L — External longitudinal 
 commissure and internal 
 capsule. 
 
 y P — Posterior cornu. 
 
 PO — Parieto-occipital fissure. 
 
 Q — Lobus quadratus. 
 
 pi — First parietal conv. 
 
 ps — Angular lobe. 
 
 rf2X3 — Temporal convs. 
 
 F M — Fusiform convolution. 
 
 L G— Lingualis convolution. 
 C — Cerebellum. 
 N — Pons, lateral fibres. 
 P T — Processus testes. 
 R — Restiform body. 
 T — Fasciculus teretes. 
 F T — Fillet or lemniscus. 
 — Olivary bod}'. 
 PR — Anterior p3-ramids of 
 medulla. 
 
164 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 27. 
 
 L — External longitudinal 
 commissure. 
 
 VP — Posterior cornu and in- 
 ternal capsular fibres. 
 
 PO Parieto-occipital fissure. 
 
 Q — Lobus quadratus. 
 
 pi ps —Parietal lobes. 
 
 rf2 rps — Temporal convolu- 
 tions. 
 
 F M — Fusiform convolution. 
 
 L G — Lingualis. 
 
 C — Cerebellum. 
 
 D — Corpus dentatum. 
 
 R — Restiform body. 
 
 The olivary body and an- 
 terior pyramids are seen be- 
 neath R. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 166 
 
 
 S^A 1^' \ J It / , ''^r'*.-t i«^< 
 
 No. 28. 
 
 
 L- — External longitudinal 
 
 commissure. 
 
 Posterior fibres of the 
 
 internal capsule, posterior 
 
 cornu. 
 Po — Parieto-occipital fissure. 
 C — Apex of cuneus. 
 Q — Quadratus or precuneus. 
 
 Pi ps. ~ Parietal lobes. 
 
 rji2 rps — Temporal lobes. 
 
 F M — Fusiform convolution. 
 
 L G — Lingualis. 
 
 D— Corpus dentatum. 
 
 To — Tonsil. 
 
 U— Uvula. 
 
 R — Restiform body. 
 
166 
 
 ARCHITECTURE OF THE BRAIN 
 
 
 
 »:,, 
 
 "^1 'if 
 No. 29. 
 
 L — External longitudinal 
 commissure, internal cap- 
 sule, cornu lateral ventricle. 
 
 C A — Calcarine fissure. 
 
 C^ — Cuneus lobe. 
 
 Po — Parieto-occipital fissure. 
 
 Q — Quadratus lobe. 
 
 pi ps _Parietal lobes. 
 'J2 f 3 — Temporal lobes. 
 F M- Fusiform lobe. 
 L 6 — Lingual lobe. 
 D— Corpus dentatum. 
 To— Tonsil. 
 XJ_Uvula. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 167 
 
 No. 30. 
 
 L — External longitudinal 
 commissure, extremity of 
 posterior cornu. 
 
 C A — Calcarine fissure. 
 
 C — Cuneus. 
 
 Po— Parieto-occipital fissure. 
 
 Q — Precuneus or quadratus. 
 Qi 02 O'* - Occipital lobes. 
 T^ — Third temporal conv. 
 F M — Fusiform. 
 L G — Lingualis. 
 D — Dentate body. 
 
168 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 31. 
 
 L — External longitudinal 
 commissure, posterior 
 cornu. 
 
 C A— Calcarine fissure. 
 
 C — Cuneus. 
 
 Qi 0- 0^ —Occipital lobes. 
 '1* — Third temporal 
 F M— Fusiform. 
 L G — Lingualis. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 169 
 
 No. 32. 
 
 C A — Calcarine fissure. 
 
 C — Cuneus. 
 
 Qi 0- OS —Occipital lobes. 
 
 T* — Third temporal. 
 F M — Fusiform. 
 L €r — Lingualis. 
 
170 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 33. 
 
 C A — Calcarine fissure. 
 
 C — Cuneus. 
 
 0* 0^ 0^ — Occipital convs. 
 
 F M — Fusiform. 
 
 L G — Lingualis. 
 
TOPOGRAI'HICAL SECTIONS OF THE BRAIN. 
 
 171 
 
 No. 34. 
 
 C — Cuneus. 
 
 0^ 0^ 0^ - Occipital convs. 
 
 F M — Fusiform. 
 
 L G — Lingualis. 
 
172 
 
 ARCHITECTURE OF THE BRAIN. 
 
 No. 35. 
 
 C — Cuneus. 
 
 Ql 02 0^ - Occipital convs. 
 
 F M — Fusiform. 
 
 L 6 — Lingualis. 
 
TOPOGRAPHICAL SECTIONS OF THE BRAIN. 
 
 173 
 
 '^g^.' 
 
 No. 36. 
 
 C — Cuneus. 
 
 Ql 02 QS ^ Occipital convs. 
 
 F M — Fusiform. 
 
 L G — Lingualis. 
 
174 AECHITECTURE OF THE BEAEST. 
 
 Figure 27 represents the upper surface of the cerebellum, 
 and a section of the crura cerebri through the nates forward 
 to the posterior perforated space. Tue nates are united by a 
 commissure above the iter. The roof of the iter is arched, 
 and its floor is formed by the fasciculi teretes, which are 
 divided in the middle line by the central fissure. A section 
 of the raphe dividing the cruri cerebri extends from the me- 
 dian fissure of the iter to the posterior perforated space. 
 Surrounding the iter is a layer or tube of grey matter, which 
 is the continuation of the grey columns of the spinal cord 
 and the grey matter of the floor of tlie fourth ventricle. 
 Downward and outward from the grey matter around the iter, 
 in succession upon each side, are sections of the processus, 
 fillet, locus niger, and crusta. External to these parts, upon 
 a line with the nates on each side, are the brachia. The 
 third nerve enters the inner side of the crus cerebri, divides 
 into strife, which spread as they pass through the fibres of the 
 processus to reach the grey matter of the iter. That portion 
 of the section above the crustte, including the locus niger, is 
 called the tegmentum. The broad notch in front of the cere- 
 bellum embracing the tegmentum, is called the incisura 
 anterior, and the notch behind, the incisura posterior. Be- 
 tween these notches is an elevated portion of the cerebellum, 
 the superior vermiform process, or middle lobe of the cere- 
 bellum; its middle portion is called the monticulus, a small 
 lobe in the incisura anterior is called the lobus centralis, and 
 a few transverse convolutions behind are named the commis- 
 sura simplex. The superior vermiform process is continuous 
 behind with the inferior vermiform process of the middle 
 lobe (Fig. 29). The lateral portion of the upper surface of 
 the cerebellum contains two lobes; the square lobe in front, 
 and the semilunar lobe behind. 
 
Figure 27'. 
 
176 AECHITECTUBE OF THE BKAIN. 
 
 Figure 28 — Is an anterior view of the cerebellum, showing 
 its hilua and the relations of the parts transmitted by it, and 
 also a section of the fourth ventricle. Above the hilus is the 
 elevated middle lobe of the cerebellum, concave in front to 
 embrace the crura cerebri, called the incisura anterior. In 
 the middle of the notch is a small lobe, the lobus centralis, 
 which is the anterior extremity of the superior vermiform 
 process, and rests upon the upper surface of the valve of 
 Vieussens. Beneath the valve is the cavity of the fourth 
 ventricle, containing the nodule, which is the anterior extrem- 
 ity of the inferior vermiform process, and is in relation with 
 the under surface of the valve of Vieussens. The nodule is 
 connected on either side with the flocculus, by a thin mem- 
 brane called the commissure of the flocculi. Beneath the 
 nodule are the other parts comprising the inferior vermiform 
 process, viz: the uvula, pyramid, and commissura brevis. 
 Upon each side of the uvula are the amygdalae or tonsils, 
 external to which, on either side, are: the flocculus, digasti'ic, 
 slender, and the posterior inferior lobes, of the lateral mass of 
 the cerebellum. The lateral lobes are divided by a deep notch 
 extending from the roof of the fourth ventricle to the pos- 
 terior part of the cerebellum, the incisura posterior. 
 
 The par.s transmitted by the hilus are from within out- 
 ward: the valve of Vieussens, processes, restiform bodies, 
 and the pons, composed of a deep and superficial layer of 
 fibres. These parts compose the crura, or peduncles of the 
 cerebellum, beneath which are the flocculi on each side. 
 The convolutions and fissures of the cerebellum radiate from 
 the hilus, and the great transverse fissure of the cerebellum 
 is seen extending out laterally from each crus; and, being 
 continuous behind, divides the cerebellum into superior and 
 inferior lobes. 
 
't^/^ 
 
 ^l>^. 
 
 Fisure 28. 
 
178 ARCHITECTURE OF THE BRAIN, 
 
 Figure 29 — Is a representation of the under surface of 
 tlie cerebellum. Above and in front is tlie iucisura anterior, 
 upon each side of which is the flocculus. Behind is the in- 
 cisura posterior, and extending along the middle of the under 
 surface of the cerebellum, between the incisurse, is a deep 
 furrow, at the bottom of which is the inferior vermiform 
 process of the middle lobe of the cerebellum, the parts of 
 which, from before backward, are: the nodule, uvula, pyra- 
 mid, and commissura brevis. The inferior surface of the 
 lateral hemisphere of the cerebellum contains from within 
 outward: the tonsil, digastric, slender, and posterior inferior 
 lobes. Behind the commissura brevis and the posterior in- 
 ferior lobes, is the great transverse fissure of the cerebellum, 
 which divides the upper from the lower surfaces. The 
 separation of the sides of this fissure from behind uncovers 
 the dentate bodies which adhere to the inferior lobes of the 
 cerebellum. (See Fig. 15^.) 
 
■iura hr^'""' 
 
 S^y^"" 
 
 Fimire '^9. 
 
180 ARCHITECTURE OF THE BRAIN 
 
 Figure 30 — Is a vertical section through the middle lobe 
 of the cerebellum showing the arbor vitte. The valve of 
 Vieussens is seen to enter the hilus of the middle lobe of the 
 cerebellum and divide into numerous branches; these sub- 
 divide into minute branchlets which are distibuted to the 
 leaflets that line the sides of the fissures of the vermiform 
 processes. The convolutions of the lateral lobes of the cere- 
 bellum radiate from the central lobe and are continuous with 
 its convolutions and commissures. 
 
 Figure 31 — Is a vertical section of the lateral lobe of the 
 cerebellum, showing the convolutions and fissures of the hem- 
 ispherical ganglion, the corona radiata, and dentate body. 
 The processus enters the hilus of the cerebellum and termi- 
 nates posteriously within the corpus dentatum. 
 
^^h 
 
 w. 
 
 4 
 
 
 Figure 30. 
 
 G '> f^ 'Z ' f o n " 
 
 
 , DC nt^ 
 
 ^'^c/.-^^'- r 
 
 Figure 31. 
 
182 ARCHITECTUKE OP THK BKAIN. 
 
 Figure 32 — Is a transverse section of the crura cerebri 
 midway between the upper border of the pons Varolii and 
 the optic tract, and illustrates the crustse and the parts which 
 form the tegmentum. 
 
 Figure 33 — Is a section of the crura cerebri, immediately- 
 above the pons Varolii, and shows the same parts that are 
 seen in figure 32. 
 
 Figure 34 — Is a section of the pons Varolii midway be- 
 tween its upper border and the emergence of the fifth nerves. 
 It shows the fourth ventricle, fasciculi teretes, median fissure, 
 processus, fillet, and the deep and superficial layers of the 
 pons. 
 
 Figure 35 — Is a transverse section of the pons Varolii on 
 a level with the fifth nerves, the roots of which are seen on 
 either side. 
 
 Figure 36 — Is a section of the medulla oblongata through 
 the olivary bodies and the restiform nuclei. 
 
 Figure 37 — Is a section through the medulla oblongata at 
 the decussation of its crossed pyramidal tracts. The anterior 
 cornua of grey matter are interrupted, and the posterior cornua 
 assume a rounded form. 
 
 Figure 38 — Is a section of the spinal cord showing the 
 arrangement of its grey and white colums, its commissure and 
 central canal. 
 

 let (X 
 
 Figure 3'i. 
 
 p N 5 
 Fia,iiie 35. 
 
 ^'^^•s. 
 
 x^ 
 
 Figure ;$:}. 
 
 N 
 
 -_4l<ci-t Nut. 
 
 __1^ olive 
 -y^Fu n d. Bi' 2- n. 
 
 Fiaure 36. 
 
 olive — , 
 DecussaTnPy^'. 
 
 Figure 37. 
 
 itrr^^ Fund.RKZ 
 
 Ficuro 34. 
 
 Pos-t.MlcJ Fss / 'tolumr o; Ga.ll 
 
 Figure 38. 
 
NDEX OF CONTENTS. 
 
 PAGE 
 
 Membranes of the brain 5 
 
 The cerebro spinal axis 8 
 
 The cerebrum 12 
 
 Dissection 18 
 
 Cerebellum 36 
 
 The pons Varolii 40 
 
 The medulla oblongata and spinal cord 51 
 
 Recapitulation of the tracts of the cerebro spinal axis 63 
 
 Central origin and relation to the cranial nerves 70 
 
 The cerebral hemisphere 106 
 
 Cerebral localization 128 
 
NDEX OF ILLUSTRATIONS. 
 
 FIGURES 
 
 Surface of the cerebrum 1 and 2 
 
 Corpus callosum and superior longitudinal commissure 3 
 
 Fornix and lateral ventricles 4 
 
 Velum interpositum and choroid ple.xus 5 
 
 Basal ganglia and superior surface of cerebellum 6 
 
 Base of the brain and lateral veiw of internal capsule 7 
 
 Posterior view of the intermedia 8 
 
 Lateral view of the intermedia 9 
 
 Posterior dissection of the intermedia 10 
 
 Dissections of crus cerebri, pons and medulla .... .11, 12, 13, 14 
 
 Fourth ventricle, processes and red nuclei 15 
 
 Relations of cerebellar peduncles and corpus dentatum 15| 
 
 External surface of the hemispherical ganglion 16 
 
 Internal surface of the hemispherical ganglion 17 
 
 Insula IS 
 
 External capsule and external longitudinal commissure 19 
 
 Lenticular nucleus and external longitudinal commissure and 
 
 external capsule 20 
 
 Relations of crusta, fillet, thalamus and external longitudinal 
 
 commissure 21 
 
 Relations of anterior commissure, crusta, fillet, thalamus ... 22 
 
 Intrahemispherical view of the internal surface of hemisphere 23 
 
 Relation of the convolutions and fissures to the skull 23^ 
 
 Cerebral localization, after Horsley 24 
 
 Cerebral localization, after Ferrier 25 
 
 Median section of the brain 26 
 
 Upper surface of the cerebellum . 27 
 
 Anterior view and hilus of cerebellum 28 
 
 Inferior surface of cerebellum 29 
 
 Arbor vita; 30 
 
 Section of lateral lobe, cerebellum 31 
 
 Section of crus cerebri, tegmentum and crusta 32 
 
 Section of crus cerebri above the pons Varolii 33 
 
 Sections of pons Varolii 34 and 35 
 
 Section of medulla oblongata 36 
 
 Section of decussation of anterior pyramid 37 
 
 Section of spinal cord 38 
 
 Shirty-six topographical sections of the brain . . . .pages 137 to 173 
 
INDEX. 
 
 Anterior commissure of third ventricle, 
 
 p. 20; Figs, 6-13-14; Sec. 14-15. 
 Anterior median fissure, p. 9; Figs. 7-9. 
 Anterior peduncles of corpus callosum, 
 
 p. 21; Figs. 7-26, 
 Anterior pyramids of medulla oblonga- 
 ta, pp. 57-59; Figs. 9-11. 
 Anterior root zone of spinal cord, pp. 
 
 47-57; Figs. 7-10 to 13. 
 Aperculum, p. 111. 
 Acquaduct of Sylvius, or iter, p. 27; 
 
 Figs. 26-27-32-33. 
 Arachnoid membrane, pp. 5-7. 
 Arbor vits, p. 37; Figs. 26-30, 
 Arciform fibres of medulla, p. 60; Figs. 
 
 7-9. 
 Basal ganglia, pp. 17-29; Figs. 6 to 10; 
 
 Sec 10 to 18. 
 Basilar groove, p. 9; Figs. 9-27. 
 Bichat, fissure of, pp. 10-13. 
 Brachia, p. 28, Figs. 6-8-9-13-14. 
 Burdach's column, p. 56. 
 Calamus scriptorius, p. 48; Figs. 8-10. 
 Caudate nucleus, pp. 30-17-23; Figs. 4- 
 
 6-7; Sec. 11, 
 Central canal of spinal cord, p. 10; 
 
 Figs 8-10. 
 Central origin of cranial nerves, p. 70. 
 Cerebrum, pp. 8-12. 
 Cerebrum, superior surface of, p. 12. 
 
 Figs. 1-24-26 
 Cerebrum, inferior surface of, p. 12; 
 
 Figs. 2-7. 
 Cerebrum, structure of, p. 14. 
 Cerebral hemisphere, p. 106; Figs. 16- 
 
 17. 
 Cerebral localization, p. 128; Figs. 23;^- 
 
 24-25. 
 Cerebellum, pp. 8-36; Figs. 6-7-27 to 
 
 31. 
 Cerebro-spinal axis, p. 8. 
 Choroid plexus, pp. 24-23-7; Figs. 4-5. 
 Choroid plexus of third ventricle, p. 25. 
 Note.— Sec. signifies Topographical Sectio 
 
 Claustrum, pp. 17-34; Sec. 10 to 18. 
 
 Clavate nuclei, p. 48; Figs. 8-10. 
 
 Commissure of gyrus fornicatus, p. Ill; 
 Fig. 3-23. 
 
 Comparison of cerebrum and cerebel- 
 lum, p. 38. 
 
 Connection of superior and inferior pe- 
 duncles of the cerebellum with the 
 corpus dentatum, p. 38. 
 
 Convolutions of hemispherical ganglion, 
 p. 111. 
 
 Cordon, pp 111-107; Fig. 17. 
 
 Cornua of lateral ventricles, p. 22; Fig. 
 5 
 
 Corona radiata cerebrum, pp. 16-18; 
 Figs. 3 to 6, 
 
 Corona radiata, cerebellum, p. 25. 
 
 Corpora albicantia, p. 15; Figs. 7-9. 
 
 Corpora geniculata, pp 28-29; Figs. 7- 
 8-9 
 
 Corpora quadrigemina, p. 27; Figs 6- 
 8-9. 
 
 Corpus callosum, p. 18 13-16; Figs. 3- 
 8-23-26 
 
 Corpus fimbriatum, pp 23-24; Figs, 4-5. 
 
 Corpus dentatum, p, 37; Figs. 8 to 15}^. 
 
 Crests of corpus callosum, pp. 18-23; 
 Figs. 3-8. 
 
 Crossed pyramidal tracts, pp. 56. 
 
 Crusfa, pp. 15-34; Figs. 2-7 to 12. 
 
 Decussation anterior pyramids of me- 
 dulla. Figs. 7-11 to 14. 
 
 Decussation corpus callosum and inter- 
 nal capsule, p. 16; Figs. 3-8; Sec. 
 18-19. 
 
 Direct cerebellar tract, p. 56. 
 
 Direct pyramidal tract column of Turck, 
 p. 55. 
 
 Dissection, p. 18. 
 
 Dura mater, p. 5. 
 
 Eminentia collateralis, p. 22; Fig. 5. 
 
 External basal ganglion cerebrum, p. 33; 
 Figs. 9-12-20. 
 
INDEX — Continued. 
 
 External basal ganglion cerebellum, p. 
 
 39. 
 External capsule, pp. 17-33; Figs. 7-9- 
 
 19; Sec. 10 to 18. 
 External longitudinal commissure, pp. 
 
 19-20. 
 Falx cerebri, p. 5. 
 Fascia dentata, p. 111. 
 Fasciculi teretes, pp. 44-47; Figs. 10-15- 
 
 25. 
 Fifth ventricle, p. 24; Figs. 4 to 8. 
 Fillet or lemniscus, p. 43; Figs. 10 to 14, 
 
 26. 
 Fillet fibres from fourth ventricle, p. 47; 
 
 Figs. 11-12-13. 
 Fissures, anterior median, p. 9. 
 Fissures, longitudinal, p. 10. 
 Fissures, Bichat or transverse, pp. 10- 
 
 13-23; Figs. 4-5. 
 Fissures, posterior median, p. 10. 
 Fissures, olfactory, p. 15. 
 Fissures, Sylvius, pp. 13-108; Figs 2-7- 
 
 16-24. 
 Fissures, Rolando, p. 108; Figs. 24-25- 
 
 231^. 
 Fissures, calloso-marginal, p. 110; Fig. 
 
 17. 
 Fissures, parieto-occipital, p. 110; Fig. 
 
 17. 
 Fissures, calcarine, p. 110; Fig. 17. 
 Flocculi, p. 36; Figs. 7-28, 
 Foramen of Monro, p. 23; Figs. 4-5. 
 Foramen of Majendie, p. 64. 
 Formatio reticularis, p. 20. 
 Fornix, p. 23; Fig. 4. 
 Fourth ventricle, pp. 48-11; Figs. 8-10- 
 
 13-15-26. 
 Frontal lobes, p. 12; Fig. 2. 
 Fundamental root zone, pp. 15-28-46-47- 
 
 55; Figs. 8-9-11-12-13. 
 Fusiformis lobe of thalamus, p. 32; 
 
 Fig. 6. 
 Ganglion of pons Varolii, p. 45; Figs. 
 
 34-35. 
 Geniculate bodies, p. 14; Figs. 8-9-11-12. 
 Genu of corpus callosum, p. 21; Figs. 
 
 4-5-6-26. 
 Genu of internal capsule, pp. 24-30; 
 
 Figs 4-7-8. 
 Globus pallidus, p. 33. 
 Cowers' sensory tract, p. 57. 
 
 Great longitudinal fissure, p. 10; Figs. 
 
 1-2-17-24-26. 
 Groove separating corpura quadrige- 
 
 mina, p. 10; Fig. 8. 
 Gyrus fornicatus, p. 18; Figs. 17-26. 
 
 Hemispherical ganglion cerebrum, pp. 
 
 17-106; Figs. 16 to 23. 
 Hemispherical ganglion cerebellum, p. 
 
 38; Fig. 151^. 
 Hilus of cerebrum, p. 18; Figs. 2-17. 
 Hippocampus major, minor, p. 22; Fig. 5. 
 Incisura cerebelli, p. 10; Figs. 27-29. 
 Infundibulum, p. 26; Figs, 7-9. 
 Insula, p. 17; Fig. 18. 
 Internal capsule, pp. 16-29; Figs. 4 to 
 
 14, 18 to 22; Sec. 10 to 19. 
 Internal layer corona radiata, p. 20. 
 Internal basal ganglia, p. 30; Fig. 6; 
 
 Sec. 9 to 17. 
 Internuncial fibres, p. 19; Figs. 3, 18 to 
 
 22. 
 Interpeduncular space, pp. 9-26; Figs 
 
 2-7-9, 
 Iter, p. 11; Figs. 10-15-26-27. 
 Lamina cinerea, pp. 21, 26; Figs. 9- 
 
 11-12. 
 Lateral ventricle, pp, 22-11; Fig. 4. 
 Layers of corona radiata, p. 20; Figs. 
 
 20-21; Sec. 25. 
 Layers of pons Varolii, p 45; Figs 9- 
 
 11-12. 
 Lemniscus, see fillet, p. 43; Figs. 10 to 
 
 14, 26. 
 Lenticular nucleus, pp. 33-17; Figs. 7- 
 
 9-12-20; Sec. 17. 
 Ligamentum dentatum, p. 6. 
 Lobes of cerebellum, p. 36. 
 Loci cserulii, p. 49. 
 Locus niger, p. 45; Figs. 10-11-12 32-33; 
 
 Sec. 20-21. 
 Longitudinal commissures, p. 20; Figs. 
 
 3-4-9-18 to 21. 
 Lyra, p. 24; Figs. 5-6. 
 Median fissure, p, 9, 
 Medulla oblongata and spinal cord; pp, 
 
 57-51; Figs 2 to 15. 
 Middle commissure third ventricle, p. 
 
 26; Figs. 6-26. 
 Membranes of the brain, p. 5. 
 Mixed lateral tract of spinal cord, p. 57. 
 
INDEX— Continued. 
 
 Nates (see corpora quad, page 27.) 
 Nerves of Lancisi, p. 21; Fig. 3. 
 Nucleus of pons Varolii, p. 45; Figs. 
 
 34-35. 
 Occipital lobes, p. 13. 
 Olfactory nerve bulb and fissure, p. 12; 
 
 Figs, 2-7. 
 Olivary bodies, p. 60; Figs. 9 to 14. 
 Olivary fasciculus, pp. 47-60; Fig. 12. 
 Optic commissure, p. 26; Figs. 2-7. 
 Peduncles of cerebrum, p. 14; Figs. 2- 
 
 7-8-9-10-26-27. 
 Pes hippocampi, accessorius, p. 22; 
 
 Fig. 5. 
 Pia mater, p. 6. 
 
 Pillars of pineal body, p. 27; Figs. 6-8. 
 Pineal gland, p. 27; Figs. 6-8. 
 Pison, p. 31; Fig. 6. 
 Pituitary body, p. 26. 
 Pons Varolii, p 40; Figs, 7-9 to 14. 
 
 Structure of, p. 42. Dissection of, p 
 
 44; Figs. 11 to 14. 
 Posterior median column. Gall's, p. 55; 
 
 Figs. 8-10, 
 Posterior median fissure, p. 10; Figs, 
 
 8-10, 
 Posterior pillars of fornix, p. 24; Figs, 
 
 4-5, 
 Posterior pyramids of medulla, p, 57; 
 
 Figs, 8-10-15, 
 Posterior root zone, Burdach's column, 
 
 p, 56, 
 Processus, pp, 15-28; Figs. 8 to 15-27-28, 
 Pulvinar, p, 32; Fig, 0, 
 Puncta vasculosa, p, 19; Fig, 8, 
 Putamen, p. 33. 
 Raphe of cerebral peduncles, p. 14; 
 
 Figs. 26-27 33. Oval opening in, p. 
 
 43; Fig. 26. 
 Raphe of corpus callosura, p. 21; Fig. 3. 
 Recapitulation of tracts cerebro-spinal 
 
 axis, p. 63. 
 Red nucleus, p. 32; Figs. 10-13-15; Sec. 
 
 19-20. 
 Restiform body, p. 61; Figs. 8 to 15. 
 Restiform nucleus, p. 49; Figs. 8-10-36. 
 Restiform system, p. 62. 
 Restiform triangle, pp. 47-61; Figs. 9 
 
 to 13. 
 Section of corpus callosum, p. 21; Fig. 
 
 26. 
 
 Septum lucidum, pp. 22-23-24; Figs. 4 
 
 to 10-26. 
 Spinal cord, pp. 8-51. 
 Splenium, p. 21; Figs. 4-5-26. 
 Striae, longitudinales, p. 21; Fig. 3. 
 Strife, transversEE, p. 49; Figs. 8-10. 
 Structure of cerebrum, p. 14. 
 Subarachnoid spaces, p. 6. 
 Subthalmic ganglion (red nucleus), p. 
 
 32; Figs. 10-13-15. 
 Superior longitudinal commissure, p. 21; 
 
 Figs. 3-23. 
 System, cerebello spinal, p. 68. 
 System, fillet, p. 67. 
 System, ganglionic, p. 64. 
 System, motor, p. 66. 
 System, organic and sensory, p. 68. 
 System, respiratory reflex, p. 68. 
 System, ventricular, p. 63. 
 System, visual reflex, p. 66. 
 
 Taenia semi circularis, pp. 30-23: Figs. 
 
 6-7-8. 
 Tegmentum, pp. 15-16-34; Fig. 32. 
 Temporal lobes, p. 12. 
 Tentorium cerebelli, p. 5. 
 Testes (see corpora quad.) p. 27. 
 Thalamus opticus, pp. 17-23-31; Figs. 
 
 6-8-10. 
 Third ventricle, pp. 26-11; Figs. 6-8-10- 
 
 1.V26. 
 Tracts of spinal cord, p. 55; Figs 7 to 
 
 15-38. 
 Transverse fissure of Bichat; p. 10; 
 
 Fig. 26. 
 Triangle to illustrate aphasia, p. 19, 
 Tnber cinereum, p, 26; Figs, 7-9. 
 Tubereulum Thalami, p. 32; Fig. 6. 
 
 Valve of Vieussens, pp. 10-28; Figs. 8- 
 
 10-26. 
 Vena Galeni, p. 25; Fig. 5. 
 Velum interpositum, pp. 10-25; Fig. 5. 
 Ventricle of corpus callosum, p. 18. 
 Ventricular system, pp. 10-63. 
 Vermiform processes of cerebellum, p. 
 
 36; Figs. 26-27-31. 
 Vertical depression of crus cerebri, pp. 
 
 14-15; Figs. 8-9. 
 Vesicular columns of Clarke, p. 52; 
 
 Fig. 38. 
 Vesicular columns of spinal cord. p. 52. 
 
FULLER ANATOMICAL CO., 
 
 MANUFACTURERS OF 
 
 ANATOMICAL AND PATHOLOGICAL MODELS, 
 GRAND RAPIDS, MICH. 
 
 Casts nqade of soft tissues, ttinqors, etc., of natural size aqd 
 
 sl^ape arid representing niiriute details. 
 Tl^e specirnens returned ■wit]:]out injury. 
 Plates taKen direct frorn tl^e object for tl^e illustration of 
 
 booKs and papers a specialty 
 
 PRICES OF MODELS OF THE BRAIN. 
 
 Student's set, of six pieces in a box, represented b}' figures 1 
 
 to 7 and 16 and 17 $15.00 
 
 Six lateral dissections of hemispliere on a placque 15.00 
 
 Dissections of the intermedia, six pieces. Figs. 8 to 14- 25.00 
 
 Topographical sections natural shape of brain, in a box -25.00 
 
 i&° Dr. Fuller's models of the brain were awarded the medal and 
 diploma of the World's Columbian Exposition, and were purchased bv the 
 University of Chicago. 
 
COLUMBIA UNIVERSITY LIBRARIES 
 
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