"^r^T-^. li.L^.Mijl. COLLEGE OF PHYSICIANS AND SURGEONS LIBRARY "T^^ \ A TREATISE ON THE DISEASES OF THE NERVOUS SYSTEM. Digitized by tine Internet Arciiive in 2010 witii funding from Open Knowledge Commons http://www.archive.org/details/treatiseondiseas02ross A TREATISE THE DISEASES NERVOUS SYSTEM. JAMES ROSS, M.D. MEMBER OP THE EOTAL COLLEGE OF PHYSICIANS, LONDON ; ASSISTANT PHYSICIAN TO THK MANCHHSTEB KOYAL INFIKMART ; CONSULTING PHYSICIAN TO THE MANCHESTER SOUTHERN HOSPITAL. ILLUSTRATED WITH LITHOGRAPHS, PIIOTOGHAPHS, AND TWO HUNDRED AND EIGHTY WOODCUTS. Volume II. NEW YORK : WILLIAM WOOD & COMPANY^ 1882. IZ2Z V. 2— CO o 3S CONTENTS OF VOLUME II. BOOK II. SPECIAL PATHOLOGY OF THE NERVOUS SYSTEM (Continued). Part III. DISEASES OF THE SPINAL COED AND MEDULLA OBLONGATA. PAGE. Chapter I. Anatomical and Physiological Introduction ... 3 Chapter II. Morbid Anatomy and Classification of the Diseases of the Spinal Cord and Medulla Oblongata. (i.) Morbid Anatomy 84 (ii.) Classification 100 Chapter III. System Diseases of the Spinal Cord and Medulla Oblongata. (i.) Poliomyelopathies. 1. Poliomyelitis Anterior Acuta ... ... 105 2. Poliomyelitis Anterior Chronica ... 136 3. Progressive Muscular Atrophy ... ... 145 4. Primary Labio-glosso-Laryngeal Paralysis 173 5. Pseudo- Hypertrophic Paralysis ... 185 Chapter IV. System Diseases of the Spinal Coed and Medulla Oblongata {continued). (ll.) Leucomyelopathies. 1. Progressive Locomotor Ataxy ... ... 211 2. Sclerosis of the Columns of GoU ... 249 3. Sclerosis of the Direct Cerebellar Tracts ... 250 4. Lateral Sclerosis 251 VI TABLE OF CONTENTS. PAGE. Chapter V. Mixed Diseases of the Spinal Cord and Medulla OsLONaATA. (i.) Paralysis Ascendens Acuta 264 (n.) Acute Diffused Myelitis 272 (in.) Chronic Diffused Myelitis 292 (iv.) Myelomalacia ... 308 Chapter VI. Vascular Diseases of the Spinal Cord and Medulla Oblongata. (i.) AnBsmia, Thrombosis, and Embolism of the Spinal Cord and Medulla Oblongata. 1. A nsemia of the Spinal Cord ... ... ... 310 2. Anaemia of the Medulla Oblongata — Throm- bosis and Embohsm — Necrotic Softening. 313 (ii.) Hypereemia and Haemorrhage of the Spinal Cord and Medulla Oblongata. 1. Hyperaemia of the Spinal Cord and its Mem- branes ... ... ... ... ... 317 2. Haemorrhage into the substance of the Spinal Cord 321 3. Hyperaemia and Haemorrhage of the Medulla Oblongata 327 Chapter VII. Functional and Secondary Diseases of the Spinal Cord and Medulla Oblongata. (i.) Spinal Irritation 332 (il) Neurasthenia Spinalis ... ... ... ... ... 335 (ill.) Keflex and Secondary Paraplegia 339 (iv.) Saltatory Spasm ... 341 (v.) Tonic Spasms in Muscles capsible of Voluntary Movement 342 (vi.) Intermittent Spinal Paralysis ... ... ... ... 343 (vil) Toxic Spinal Paralysis 344 (viii.) Hysterical Paraplegia ... ... 344 Chapter VIII. Traumatic Diseases, Tumours, and Abnor- malities OP the Spinal Cord and Medulla Oblongata. (i.) Wounds of the Spinal Cord and Medulla Oblongata . . . 346 (ii.) Slow Compression of the Spinal Cord and Medulla Oblongata ... ... ... 351 (in.) Hemiplegia et Hemiparaplegia Spinalis 361 (iv.) Concussion of the Spinal Cord ... ... 368 (v.) Tumours of the Spinal Cord and Medulla Oblongata 372 TABLE OF CONTENTS. Vll PAGE. Chapter IX. Diseases of the Membranes op the Spinal Cord AND Medulla Oblongata. (i.) Vascular Diseases of the Membranes. 1. Hypersemia of the Spinal Membranes ... 381 2. Meningeal Apoplexy (Hsematorrhachis)... 381 (ii.) Pachymeningitis Spinalis. 1. Pachymeningitis Spinalis Externa ... ... 384 2. Pachymeningitis Spinalis Interna (Hyper- trophica et Hsemorrhagica) 386 (ill.) Leptomeningitis Spinalis. 1. Leptomeningitis Spinalis Acuta 391 2. Leptomeningitis SpinaUs Chronica ... ... 396 (iv.) Tumours of the Spinal Membrane ... 400 (v.) Deformities of the Spinal Membranes 404 Part IV. DISEASES OF THE ENCEPHALON. Chapter I. Anatomical and Physiological Introduction . . . 409 Chapter II. Morbid Anatomy and Classification of the Diseases of the Encephalon. (l) Morbid Anatomy of the Encephalon 501 (ii.) Classification of the Diseases of the Encephalon 508 Chapter III. General Consideration of Focal Diseases, According to the Nature of the Lesion. 1. Occlusion of the Intracranial Vessels 511 {a) Occlusion of the Cerebral Arteries 511 (6) Thrombosis of the Cerebral Sinuses ... 518 (c) Occlusion of the Cerebral Capillaries ... 523 Chapter IV. General Consideration op Focal Diseases, According to the Nature of the Lesion (con- tinued). 2. Intracranial Hsemorrhage .... .... ... ... 525 (a) Cerebral Haemorrhage ... ... ... 525 (6) Meningeal Haemorrhage 543 Chapter V. General Consideration of Focal Diseases, According to the Nature op the Lesion (con- tinued). 3. Intracranial Tumours 547 vm TABLE OF CONTENTS. PAGE. Chapter VI. Special Consideration of Focal Diseases, According to the Localisation of the Lesion. 1. Affections of the Peduncular Fibres and Internal Capsule. a. Affections of the Pyramidal Tract. (i.) Hemiplegia 568 (ii.) Hemispasm 569 b. Affections of the Sensory Peduncular Tract. Hemiansesthesia ... ... ... 582 Chapter VII. Special Consideration of Focal Diseases, According to the Localisation of the Lesion (continued). 2. Cortical Lesions. a. Lesions in the Area of the Middle Cerebral Artery, (i.) Monospasms and Unilateral Convul- sions ... ... ... ... ... 594 (ii.) Cortical Paralyses and Monoplegise ... 599 (iii.) Affections of Speech from Cortical Disease ... 612 b. Lesions in the Area of the Posterior Cere- bral Artery 633 c. Lesions in the Area of the Anterior Cere- bral Artery ... ... ... ... 640 Chapter VIII. Special Consideration of Focal Diseases, According to the Localisation op the Lesion (continued). 3. Lesions of the Basal Ganglia, External Capsule, and Claustrum. (a) Lesions of the Lenticular Nucleus ... ... 643 (6) Lesions of the Caudate Nucleus ... 645 (c) Lesions of the Optic Thalamus ... ... 649 (d) Lesions of the Corpora Quadrigemina . . . 649 (e) Lesions of the Claustrum and External Capsule 650 (/) Lesions of the Base of the Skull. (i.) Lesions of the Anterior Fossse of the Skull 651 (ii.) Lesions of the Middle Fossae of the Skull 651 (iii.) Haemorrhage into the Lateral Ven- tricles ... ... ... ... ... 655 (iv.) Tumours in the neighbourhood of the Pituitary Body 655 TABLE OF CONTENTS. IX PAGE. Chapter IX. Special Consideration of Focal Diseases, According to the Localisation of the Lesion {contimied). 4. Lesions localised in the Structures situated below the Tentorium. a. Lesions in the Pons and Pedmicles of the Cerebrum ... 661 h. Lesions in the Peduncles of the Cerebellum 670 c. Lesions in the Cerebellum ... 671 Chapter X. Diffused Diseases op the Encephalon. (i.) Anaemia and Hypersemia of the Brain. (i.) Anaemia of the Brain ... •■• 685 (ii.) Hypersemia of the Brain ... ... ••• 693 Chapter XL Diffused Diseases op the Encephalon {con- tinued). (ii.) Atrophy and Hypertrophy of the Brain. (i.) Atrophy of the Brain ... 703 (ii.) Hypertrophy of the Brain 706 Chapter XII. Diffused Diseases of the Encephalon {con- tinued). (ill.) Shock and Concussion. (i.) Shock 710 (ii.) Concussion ... ... ... ... ... 716 Chapter XIII. Diffused Diseases of the Encephalon {con- tinued). (iv.) Encephalitis. 1. Diffused or General Encephalitis 724 2. Partial or Local Encephahtis 724 a. Acute Encephalitis complicating affections of the Bones of the Skull 727 b. Acute Pyaemic Encephalitis 728 c. Encephahtis around pre-existing Lesions in the Brain 728 d. Chronic Abscess of the Brain 731 X TABLE OF CONTENTS. PAGE. Chapter XIV. Diseases of the Membranes of the Brain. (i.) Diseases of the Dura Mater. (i.) External Pachymeningitis ... ... ... 743 (ii.) Internal Hsemorrhagic Pachymeningitis 745 Chapter XV. Diseases of the Membranes of the Brain {con- tinued). (ii.) Diseases of the Pia Mater. 1. Leptomeningitis Infantium ... ... ... ... 751 2. Tubercular Meningitis ... 754 Chronic Hydrocephalus ... ... ... ... 770 3. Basilar Meningitis ... ... ... ... 774 4. Meningitis of the Convexity of the Brain ... ... 778 5. Metastatic Meningitis 784 6. Traumatic Meninfflitis ... 786 Part V. DISEASES OF THE ENCEPHALO-SPINAL SYSTEM. Chapter I. Paralysis Agitans, and Multiple Sclerosis. (i.) Paralysis Agitans 791 (ii.) Multiple Sclerosis ... 801 Chapter II. Chorea, and Meniere's Disease. (l.) Chorea 814 (ii.) M6nidre's Disease 830 Chapter III. Epidemic Cerebro-spinal Meningitis, Tetanus, and Hydrophobia. (r.) Epidemic Cerebro-spinal Meningitis ... ... ... 834 (ii.) Tetanus 842 (ill.) Hydrophobia 855 Chapter IV. Hysteria 865 Chapter V. Catalepsy, Trance, Ecstasy, and other Allied Conditions. (i.) Catalepsy 904 (II.) Trance 907 (ill.) Ecstasy 907 (iv.) Somnambulism and Hypnotism 908 TABLE OF CONTENTS. XI PAGE. Chapter VI. Epilepsy and Eclampsia. (l) Epilepsy 913 (n.) Eclampsia 945 Chapter VII. Toxic, and Febrile and Post-febrile Nervous Disorders. (i.) Alcoholic Nervous Diseases ... ... 953 (ll.) Saturnine Nervous Diseases ... ... ... ... 955 (ill.) Mercurial Nervous Diseases 961 (iv.) Syphilitic Nervous Diseases 962 (v.) Febrile and Post-Febrile Nervous Diseases 975 BOOK II. SPECIAL PATHOLOGY OF THE NERVOUS SYSTEM. SPECIAL PATHOLOGY OF THE NERVOUS SYSTEM. Part HI— DISEASES OF THE SPINAL CORD AND MEDULLA OBLONGATA. CHAPTER I. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. (I.) -STRUCTURE OF THE SPINAL MEMBRANES. The spinal cord is surrounded by a compound connective-tissue sheath, consisting of (1) the dura niater, (2) the arachnoid, and (3) the pia mater. § 349. (1) The dura mater is composed of lamellae, each of which consists of a layer of parallel bundles of fine connective- tissue fibres. Flattened, more or less branched connective-tissue cells lie between the lamellae ; they lie in spaces which com- municate with one another, the latter constituting the lymph- canalicular system. The inner surface of the dura mater is lined by a thin hyaline elastic membrane, which is covered by a continuous layer of nucleated endothelial plates. The outer surface is also covered with a continuous layer of endothelium. The dura mater is richly supplied with blood-vessels and nerves. (2) The arachnoid sheath is a delicate membrane, composed of parallel bundles of connective-tissue fibres, longitudinally disposed, with connective-tissue corpuscles lying between them. The outer surface is covered by one or two layers of endothelial plates, constituting an endothelial membrane. On the inner surface is a fenestrated membrane, composed of anastomosing, transversely disposed trabeculse of connective-tissue fibres, the 4 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION, inner surface of which is covered by a single layer of endo- thelial plates. (3) The pia mater consists of an external and internal portion. The former is composed of longitudinal bundles of connective-tissue fibres, and its external surface is covered by an endothelial layer (Klein). The internal portion, or intima pise, Fig. 100. Fig. 100 (After Key and Retzius). Transverse Section of the Spinal Cord in the ujiper dorsal region, ivith its membranes. — Close on the inner surface of the dura (A) lies the arachnoid (B), which is thrown into longitudinal folds at intervals. In the posterior subarachnoidal space (the part behind the ligamenta denticu- lata, G), the septum posticum (G) may be observed in the middle, with its numerous partitions, along with the subarachnoidal spaces which they enclose. The septum becomes partly attached to the arachnoid externally, and partly spreads laterally over the inner surface of that membrane (D). The septum spreads internally over the pial sheath as the epipial subarachnoidal tissue (E), forming numerous small spaces. Two vessels may be observed in this epipial space. F, the posterior nerve roots, surrounded by the subarachnoidal membranes. The space (I) between the latter membranes and the septum posticum is of variable depth. K is the space between the posterior nerve roots, with their membranes, and the ligamentum denticulatum ; this space being free from membrane throughout the entire length of the cord, the subarachnoidal fluid finds a freer passage through it than through any other part of the posterior subarachnoidal space. Anterior to the ligamenta denticulata (G), the anterior subarachnoidal space may be observed free from membrane. H, the anterior nerve roots. Fig. 101. ElG. 101 (From Key and Eetzius). Diagram of a Transverse Section of the Spinal Cord and its membranes, showing the natural size and relative positions of the cord, membranes, and spaces. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 5 is a meshwork of bundles of connective-tissue fibres, its inner surface being lined by a layer of endothelial cells. The pia mater contains numerous blood-vessels, which lie between the external and internal layers, whence they penetrate into the substance of the cord being surrounded by a prolongation of the pial sheath. The subarachnoidal tissue consists of a plexus of trabeculse of fibrous connective tissue ensheathed in endothelium and con- taining a few elastic fibres. It forms a spongy tissue between the arachnoidal and pial sheaths, and subdivides the subarach- noidal space into numerous minute lacunae. It is a prolongation of the inner portion of the arachnoid, and its trabeculse contain larger and smaller blood-vessels. Ligainentum denticulatum stretches like a diaphragm between the arachnoid and pial sheaths on each side of the cord, from the foramen ovale magnum down to the filium ter- minale, between the anterior and posterior nerve roots. The subarachnoidal space is consequently divided into an anterior and posterior chamber. The ligamentum denticulatum consists of trabeculse of connective-tissue bundles, the trabeculse being covered with endothelium. The tissue passes into the external layer of the pia mater (Klein). Isolated connective-tissue trabeculse also extend between the dura mater and arachnoid; they are ensheathed in endothelium, while blood-vessels and nerves pass from the one membrane to the other. These trabeculas are most numerous in the posterior parts of the cord. Between the dura mater and arachnoid is the subdural, and between the arachnoid and pia mater is the subarachnoidal lymph space. Neither of these spaces form one open and free cavity, inasmuch as numerous connective-tissue trabeculse pass between the dura mater and arachnoid, and between the latter and pia mater. The two spaces do not, however, communicate with one another. The nerve roots receive a prolongation from both the arachnoidal and dural sheaths, and consequently the lymph spaces of the peripheral nerves and their ganglia have been injected from the subarachnoidal and subdural spaces re- spectively (Key and Retzius). 6 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION, (II.)- STRUCTURE OF THE SPINAL COE,D AND MEDULLA OBLONGATA. The spinal cord consists of a framework, with grey and white matter embedded in it. § 850. The framework consists of the following parts : — (1) Connective-tissue Processes. — Processes of fibrous con- nective tissue pass from the intima pise into the anterior fissure, and at different points of the circumference of the cord, where they form septa, which divide the white columns of the cord into segments. These prolongations of the intima pisD carry blood-vessels into the cord. (2) Neuroglia. — The chief part of the framework consists of a semi-fluid substance named the neuroglia-matrix. This substance presents a granular aspect under certain reagents, but is homogeneous in the fresh condition. Numerous minute fibrils, which anastomose with one another in a network, are Fig. 102. Fig. 102 (From Henle's Anatomic). Diagram of the Spinal Cord and its Membranes. 1, the dura mater; 2, the arachnoid, and (3) the pia mater; 4, the cortical layer of the neuroglia. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 7 embedded in this substance. These fibrils have a longitudinal direction, except in the septa, where they form transverse net- works, and in the grey substance, where they extend uniformly in all directions (Klein). Flat, branched, nucleated connective- tissue corpuscles are found in connection with the network of the neuroglia fibrils. The neuroglia, therefore, is composed of neuroglia-matrix, neuroglia fibrils, and branched cells, the latter being named Deiter's cells (Fig. 103). Fig. 103. Fig. 103 (From Henle's Anatomie). Deiter's Cdh. Didribution of the Neuroglia. — The neuroglia is abundant in the fol- lowing parts ; — («) On the external surface of the cord, where it forms a peripheral crust beneath the intima piae, the latter being easily separated from the former. {h) In the septa which pass between different sections of the white matter ; the posterior fissure being, indeed, only a septum of this kind (Klein). (c) It forms the ground substance of the anterior and posterior nerve roots. (d) A layer of neuroglia of considerable thickness surrounds the epi- thelial lining of the central canal, named the central grey nucleus of KoUiker. (e) A peculiar form of neuroglia is found in the posterior portion of the posterior grey horns forming the substantia gelatinosa of Eolando. The neuroglia is always more abundant near the grey matter and in the peripheral crust than in the parts between them. 8 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. § 351. The grey '^natter occupies the central parts of the cord in the well-known shape of an H. The median part contains the central canal, and the "central grey nucleus" of Kolliker the anterior grey and white commissures lying in front and the pos- terior commissure behind it. The lateral parts or columns con- sist of an anterior, middle, and posterior part ; the first of these representing the anterior, and the last the posterior grey horn; while the middle portion on each side of the central canal consists of the vesicular column of Clarke, and what may be called the central column. The central grey nucleus of Kolliker may indeed be regarded as a portion of the central column. The grey matter consists of a (1) matrix of neuroglia, (2) ganglion cells, and (3) nerve fibres. (1) The neuroglia of the grey matter is similar to that of the white. It is looser in texture and more spongy in the central grey column than in either the anterior or posterior horns, and in this situation it also contains a relatively larger number of Deiter's cells. (2) The ganglion cells of the anterior horns are relatively large, branched cells, containing in some animals masses of yellow pigment ( § 13 ). These cells are surrounded by a lymph space, through which the processes of the cell pass. The ganglion cells of the posterior horns are much smaller and less branched than those of the anterior horns. Some of the latter appear spiadle-shaped, but each extremity is branched into several processes. (3) The nerve fibres of the grey matter are of different kinds. The great bulk of the grey matter is composed of a minute and dense network of fine fibrils, named Gerlach's nerve network. The nerve network surrounding the central grey nucleus of Kolliker is less dense than in other parts. The branched pro- cesses of the ganglion cell attach themselves to Gerlach's nerve network; while the unbranched processes pass into a medul- lated nerve fibre of the anterior root. The cells of the pos- terior horns are not directly connected with any nerve fibres, but anastomose with them indirectly through Gerlach's nerve network (Klein). ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 9 § 352. The white matter is composed of medullated nerve fibres, by far the greater number being arranged in a longitudinal direction. A vertical section of the spinal cord is represented in Fig. 104, showing the longitudinal disposition of the fibres in the anterior and lateral columns. Each nerve fibre possesses an axis cylinder, and a medullary sheath, but there is no definite evidence of the presence of a sheath of Schwann, or of nerve corpuscles, as in the medullated fibres of the cerebro-spinal nerves. The nerve fibres are embedded in neuroglia as pre- viously described ; they vary much in size, some being broad, some of medium size, while others are very fine. Fig. 104. rig. 104 (From Henle's Anatomie).— Fl, Anterior column; Cga, Anterior grey horn ; Fa, Lateral column ; Ca, Posterior grey horn. The white matter also contains an oblique or horizontal direction, distinguished : — nerve fibres that have The following may be (1) The fibres of the posterior roots pass into the grey matter of the posterior horns as horizontal fibres. These fibres on entering the cord spread out laterally in the form of a fan, so that an external fasciculus, an internal fasciculus, and a median portion may be distinguished. The fibres of the external fasciculus wind forwards round the external margin of the posterior horn, and at least some of them pass forwards through the anterior commissure, a few even passing between the longitudinal fibres of the anterior column, so as to reach the internal and anterior groups of ganglion cells of the anterior grey horn of the opposite side 10 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. (Fig. 134, p"). The fibres of the internal fasciculus pass between the longitudinal fibres of the posterior root-zone to gain the posterior horn {Fig. 134, pr'). Some of them then wind round the vesicular column of Clarke, but it is not known whether they are connected with the cells of that column. A few of these fibres appear to pass behind the vesicular column of Clarke and to decussate with the corresponding fibres of the opposite side in the posterior commissure. The median portion of the posterior root enters the white matter of the posterior column, and its fibres pass for a longer or shorter distance iu a longitudinal direction, either upwards or downwards, before joining the posterior grey horns. (2) The medullated nerve fibres of the anterior nerve roots pass in an oblique direction from the grey matter of the anterior horns through the white matter. (3) The anterior commissure is said by Gerlach to be composed of medullated nerve fibres that pass from the grey matter of the anterior horn of one side into the white matter of the anterior tract of the oppo- site side. Some of the fibres, however, pass from the anterior horn of one side to the pyramidal tract of the opposite side, while others, as already described, pass from the internal fasciculus of the posterior roots of one side to the anterior grey horn of the opposite side. (4) Medullated nerve fibres emerge from the sides of the grey matter of the anterior horns, and after a short course enter the white matter of the lateral tracts (Klein). (5) Nerve fibres emerge from the posterior grey horns, and after a longer or shorter horizontal course enter the white matter of the posterior column (Gerlach). It is probable that they leave the posterior tracts again as the nerve fibres of the posterior roots (Klein). (6) Fibres emerge from the cells of the vesicular column of Clarke, which pass obliquely outwards and upwards to enter the direct cerebellar tract (Flechsig). These fibres form round bundles at the junction of the grey substance and the lateral column, and are cut transversely in hori- zontal sections. These bundles are represented in Figs. 134 to 140 as dark round spots near the formatio reticularis (fr). § 353. Distribution of the Vessels of the Spinal Cord, Medulla Oblongata, and Pons. The vertebral artery is the first and largest branch of the subclavian artery. It arises from the posterior aspect of the trunk, and ascends through the foramina in the transverse processes of all the cervical verte- brae, except the last. It winds backwards around the articulating process of the atlas, pierces the dura mater, enters the skull through the foramen magnum, and terminates at the lower border of the pons Varolii by uniting with the corresponding vessel of the opposite side to form the basilar artery. The basilar artery runs forward in the groove on the anterior surface of the pons Varolii, and divides at the anterior border of the pons into two terminal branches, one to either side. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION, 11 Fig. 105. Fig. 105 (After Duret). Arteries of the Medulla Oblongata, Pons, and Inferior Surface of the Cerebellum. 1, Hoot arteries of the spinal accessory nerve. 2, Anterior spinal arteries. 3, Arteries of the pneumogastric and glosso-pharyngeal nerves. 4, Inferior arteries of the auditory and facial nerves (vertebral branches). 5, Root arteries of the sixth nerve. 6 and 7, Arteries of the sub-olivary fossa. 8, Superior arteries of the auditory and facial nerves (branches of the middle cerebellar artery). 9, Arteries of the trigeminal nerve. 10, Arteries of the hypoglossal nerve (branches of the vertebral and anterior spinal arteries). A, Inferior cerebellar artery. B, Middle cerebellar artery. C, Superior cerebellar artery. D, Posterior cerebral artery. Branches.— The branches of the vertebral and basilar artery are the following : — Vertebral. Basilar. Lateral spinal, Transverse, Muscular branches, Middle cerebellar, Posterior meningeal, Superior cerebellar. Anterior spinal. Posterior cerebral. Posterior spinal. Inferior cerebellar. 12 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The lateral spinal branches enter the intervertebral foramina, and taking the course of the roots of the spinal nerves, are distributed to the spinal cord and vertebrae. Where the vertebral artery curves round the articular process of the atlas, it gives ofi" several muscular branches. Tlie posterior meningeal arteries are small branches which enter the cranium through the foramen magnum, to be distributed to the dura mater of the cerebellar fossae, and to the falx cerebelli. Fig. 106. Fig. 106 (After Duret). Arteries of the Pons and Medulla. 1 1', Anterior spinal artery, the bulbar branches. 2 2' 2", Inferior arteries of the pons. 3 3", Median arteries of the pons. 4, Superior arteries of the pons. 5, Posterior spinal arteries, median branches. A, Left vertebral artery. B, Basilar artery. C, Middle cerebellar artery. D, Superior cerebellar artery. E, Posterior cerebral artery. ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. 13 Tha anterior spinal artery is a small branch which unites with its fellow of the opposite side, on the front of the medulla oblongata. The artery formed by the union of these two vessels descends along the anterior aspect of the spinal cord, to which it distributes branches, and forms the commencement of the anterior median artery. The posterior spinal artery winds around the medulla oblongata to reach the posterior aspect of the cord, and descends on either side to the Cauda equina. It communicates very freely with the spinal branches of the intercostal and lumbar arteries, and near its origin sends a branch upwards to the fourth ventricle. The inferior cerebellar arteries wind around the upper part of the medulla oblongata to reach the under surface of the cerebellum, to which they are distributed. They pass between the filaments of origin of the hypoglossal nerve in their course, and anastomose with the superior cerebellar arteries. Small branches derived from these trunks pass to the choroid plexus of the fourth ventricle. Fig. 107 (After Duret). Distribution of the Arteries on the Floor of the Fourth Ventricle. A A', Posterior spinal artery. B B', Its pyramidal branches. C C C" C", Emergence of the median arteries. D D', Choroid plexus drawn to one side. (Two or three arteries may be seen to emerge from it. ) E E' E" E'", Arteries of the restiform bodies coming from the inferior cerebellar artery. 14 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The transverse branches of the basilar artery supply the pons Varolii, aud adjacent parts of the brain. The middle cerebellar artery arises from the trunk of the basilar, about its middle. It runs parallel to the transverse branches, and passes along the middle peduncle to be distributed to the anterior part of the under surface of the cerebellum. It gives off a small branch, auditiva interna, which accompanies the auditory nerve into the meatus auditorius internus, and to the labyrinth of the ear. The auditory branch is frequently de- rived directly from the basilar. The superior cerebellar arteries wind around the crus cerebri on each side, lying in relation with the fourth nerve, and are distributed to the Fig. 108 (After Duiet) 1 t ies of the Postenor Part of the Medulla and the Cerebellum, A, Choroid plexus. B, Choroid velum. C, Posterior openiDg, forming a communication between the fourth ventricle and the posterior subarachnoid space. D, Posterior pyramid. 1, Inferior cerebellar artery. 2 2", Artery of the choroid plexus. 3 3 3 3, Arteries of the choroid velum. Some proceed to the floor of the _ fourth ventricle ; they are capillary. 5, Posterior spinal artery. 6, Its ascending or pyramidal branch. 7, Its descending branch. 8, Its median branch. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 15 upper surface of the cerebellum anastomosing with the inferior cerebellar. Branches of the superior cerebellar arteries run inwards to supply the valve of Vieussens and the posterior part of the velum. The ascending cervical branch of the inferior thyroid artery gives off one or two branches {spinal branches) which enter the intervertebral foramina along with the cervical nerves, and assist in supplying the bodies of the vertebrae and the spinal cord and its membranes. The spinal branches of the aortic intercostal arteries enter the inter- vertebral foramina of the dorsal region, and supply the vertebrae, spinal cord, and membranes. The spinal branches of the lumbar, ilio-lumbar, and lateral sacral arteries enter the spinal canal through the intervertebral foramina ; they are dis- tributed like the other spinal arteries, and anastomose with them. § 354. The following arteries are distributed to the medulla oblongata and pons" — 1. The Root Arteries. — These arteries are directed laterally towards the roots of the nerves, which they penetrate near their point of emergence. They subdivide into an ascending branch, which is directed towards the nuclei of origin of the nerves, and a descending branch which descends towards the periphery. (a) Anterior Root Arteries {Fig. 109, ar). (1) The arteries of the hypoglossal nerve are derived from both the anterior spinal and vertebral arteries. (2) The arteries of the sixth nerve are derived from the basilar. (3) The arteries of the third nerve are derived from the trunk of the basilar near its termination. (6) Lateral Root Arteries {Fig. 109, Ir). (1) The arteries of the spinal accessory nerve are derived from the inferior cerebellar and vertebral arteries. (2) The arteries of the pneumogastric and glosso-pharyngeal nerves arise from the vertebral artery. (3) The arteries of the auditory, facial, and portio intermedia (nerve of Wrisberg) are derived from the vertebral a little before its termination, and from a branch of the basilar. Branches may also descend perpendicularly from the middle cerebellar artery. (4) The artery of the trigeminus is comparatively large and constant, and is derived directly 'from the basilar about its middle. Another branch is derived from the middle cerebellar artery. (5) The fourth nerve, as well as the optic and olfactory nerves, receives its arterial supply from the branches of the circle of Willis. 16 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. Fig. 109. Section of the Medulla Oblongata, showing the Distribution of the Vessels. E, Artery of the Median Raph^. Ill, Branches to the formatio reticularis. V, Branch to the olivary body. 1", Branches to the hypoglossal nucleus. 1'", ,, ,, floor of the fourth ventricle, and to the internal inferior nuclei of the facial {if), p, Pyramidal arteries. ar, Anterior root artery (hypoglossal). 2', Branch to olivary body. 2", Branches to the formatio reticularis. It terminates in branches to the hypoglossal nucleus. Ir, Lateral root artery (vagus). 5, Branch to the restiform body and the inner division of the inferior cerebellar peduncle. 5', Branches to the nucleus of the vagus. Also gives branches to the ascending root of the fifth and the formatio reticularis. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 17 / 2. Arteries of the Median Raphe (Fig. 109, R). (a) Bulbar arteries derived from the anterior spinal artery (Fig. 106, 1). (b) Inferior arteries of the pons derived from the lower end of the basilar (Fig. 106, 2 2' 2"), (c) Median arteries of the pons, derived from the trunk of the basilar (Fig. 106, 3 3"). (d) Superior arteries of the pons, derived from the superior end of the basilar (Fig. 106, 4). The annexed diagram (Fig. 110) shows that a double row of vessels enter the Raphe, the vessels on each side of th« middle line entering at different levels. A vertical section of the olivary body shows that the vessels enter the hilus in a similar manne.r ; so that the branches from the anterior root artery and the artery of the Raphe are never seen in the same horizontal section as represented in Fig. 109. 3. The Lateral Arteries of the Medulla Oblongata. (a) Anterior lateral artery (Fig. 109, ala) passes into the substance of the medulla behind the oHvary body. It gives branches to the ala, The anterior lateral artery of the medulla oblongata. It supplies branches to the formatio reticularis, olivary body, anterior nucleus of the lateral column [,alc), and terminates in branches to the hypo- glossal nucleus. mla, The middle lateral artery of the medulla oblongata. It supplies branches to the formatio reticularis, the posterior nucleus of the lateral column (pic), and terminates in branches which are dis- tributed to the external accessory nucleus of the facial {ef). pla, The posterior lateral arteries of the medulla oblongata. They supply the restiform bodies. C, Central artery. 3 3' 3", Branches to the hypoglossal and external accessory facial nuclei. mp, Median posterior artery. 4 4' 4", Branches to the external accessory facial and pneumogastric nuclei. ep, External posterior artery. It supplies branches to the internal division of the inferior peduncle of the cerebelluma and restiform body. i, Internal group of cells of the hypoglossal nucleus. al, Antero-Jateral ,, ■ >■> pi, Postero-lateral ,, ■ ,, a, Anterior ,, ,, ale, Anterior nucleus of the lateral column. pic, Posterior ,, ,, VIII, Inferior portion of the posterior median acoustic nucleus. if. Internal accessory facial nuclei. ef. External accessory facial nucleus. /, Fasciculus rotundus. XII, Hypoglossal nerve. X, Pneumogastric nerve. (t, Column of GoU. pr, Posterior root-zone. The direct cerebellar tract forms a thin band lying ex- ternal to the column of Goll and posterior root-zone. en, Clavate nucleus. tn. Triangular nucleus. 0, Olivary body. po, Parolivary body. tip. Nucleus of the pyramid. pn. Nucleus of the arciform fibres. P, Anterior pyramid. 18 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. olivary body, the anterior lateral nucleus, and terminates between the groups of ganglion cells of the hypoglossal nerve. (6) Middle, lateral artery {Fig. 109, mla) passes into the substance of the medulla in front of the restiform body. It gives branches to the posterior lateral nucleus, and terminates between the group of cells, which give origin to the lateral mixed system of nerves. (c) The posterior lateral arteries {Fig. 109, pla) enter the substance of the restiform body behind the roots of origin of the mixed lateral system of nerves. 4. The Central Artery {Fig. 109, c) of the medulla oblongata is a continuation of the central artery of the spinal cord. It subdivides into internal, middle, and external branches {Fig, 109, 3 3' 3")} which are distributed betweea the groups of cells of the hypoglossal nucleus. 5. The Median Posterior Artery {Fig. 109, mp) enters the sub- stance of the medulla oblongata on the floor of the fourth ventricle. It is probably derived from the choroid plexus. It is mainly distributed to the groups of cells which give origin to the nerves of the lateral mixed system. 6. The External Posterior Artery {Ftg. 109, ep) enters the sub- stance of the medulla at the junction of the grey substance with the restiform body. ' Fig. 110. Fig. 110 (From Henle's Anatomie). Vertical Section of Raphe of the Medulla Oblongata, showing the entrance of the vessels. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 19 § 355. Arteries of the Spinal Cord. The anterior median artery gives off a series of small branches, which pass backwards in the anterior median fissure, and reach the anterior commis- sure, hence these vessels may be called the arteries of the anterior median fissure {Fig. Ill, aj). Each of these vessels on reaching the anterior com- missure divides into two main trunks, which enter the grey substance of the anterior horns j these may be called the arteries of the anterior com- missure {Fig. Ill, ac). Fig. 111. Fig. 111. Diagram of the Distribution Anterior median artery. af, Arteries of the anterior median fissure. ac, Artery of the anterior commis- sure. 1, Anterior branch. 1'. Median branch. 1 , Posterior branch. ca, Central artery. 2, Anterior branch. 2', Median branch. 2", Posterior branch. pa. Posterior root arteries. 6 6 6", Arteries of posterior horns. ia, Internal anterior root arter}'. ea, External anterior root artery. 3 3', Internal and external branch. of tht Blood-vessels in the Sjnnal Cord. ar, Anterp-lateral branch. 4, Anterior branch. 4', Median branch. 4", Posterior branch. mr, Median lateral artery. 5 5', Anterior and posterior branches. pr, Posterior lateral arteries. ip, Internal posterior artery. mj), External posterior artery. g, Arteries of the column of Goll. PC Artery of the posterior commissure. fC, Vesicular column of Clarke. t, Internal group of cells. a, Anterior group. al, Antero-lateral group. pi, Postero-lateral group, c, Central group. m, Median area. 20 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The artery of the anterior commissure subdivides into three branches, ■which, from their position, may respectively be named the anterior {Fig. Ill, 1), median {Fig. Ill, 1'), and posterior {Fig. Ill, 1") branches. The anterior branch curves forwards, and is distributed to the anterior and internal portion of the grey substance ; the median is distributed to the lateral portion of the anterior horn, while the posterior is directed backwards to the posterior horn. The central artery also gives off an anterior {Fig. Ill, 2), median {Fig. Ill, 2'), and posterior {Fig. Ill, 2") branch, which are distributed respectively to the anterior, lateral, and posterior portions of the grey substance. The median branches of the two main vessels, besides sup- plying the grey substance, are also distributed to the pyramidal tract of the lateral column. Tlie posterior spinal artery {Fig. Ill, pa) gives off branches, which pass by the side of the posterior roots to enter the grey substance of the posterior horns, where they subdivide into a variable number of small branches {Fig. Ill, 6 6' 6"), which may be called arteries of the posterior horns. In addition to the vessels just described, a large number pass from the pia mater into the substance of the cord, and some of these are so large and so constant as to deserve special mention ; two run by the side of the bundles of fibres which constitute the anterior roots of the nerves, hence they may be called the anterior root arteries. The branch nearest the median fissure may be called the internal anterior root {Fig, 111, ia), and the other the external anterior root {Fig. lll.^a) artery. The internal anterior root artery {Fig. Ill, ia), on entering the grey substance, joins the anterior branches of the first subdivision of the artery of the anterior median fissure and of the central artery. The external anterior root artery {Fig. Ill, ea), on entering the grey substance, subdivides into two branches, the inner {Fig. Ill, 3) of which is distributed along with the vessels just mentioned ; while the outer branch {Fig. Ill, 3'^ passes between what we may call the antero-lateral {Fig. Ill, al) and central groups {Fig. Ill, c) of cells. A very constant vessel passes to the grey substance from the pia mater, at the point of junction of the anterior and lateral columns of the cord, and it may therefore be called the antero-lateral artery {Fig. Ill, ar). On reaching the grey substance it frequently divides into three branches, one of which passes in front {Fig. Ill, ar, 4 4' 4"), another behind, and another into the substance of the antero-lateral group of cells. Another constant vessel {Fig. Ill, mr) passes from the lateral aspect of the cord, and on reaching the grey substance it subdivides into two branches, the one of which passes in front and the other behind the postero-lateral group of cells {Fig. Ml, pi), and this vessel may from its position be called the median-lateral artery. Small branches {Fig. Ill, jor) pass at short inter- vals through the posterior part of the lateral column, and, together with the median branches of the first subdivision of the artery of the anterior median fissure, and of the central arteries, supply the posterior part of ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 21 the lateral columns ; hence these vessels may be called posterior lateral arteries. Two vessels pass from the pia mater into the substance of the posterior column ; the one nearest the posterior median fissure, and which may therefore be called the internal posterior artery {Fig. Ill, ip), passes between the column of Goll and the posterior root-zone ; and after passing through about two-thirds of the depth of the posterior column, it curves outwards to reach the posterior grey horn. The other vessel may be named the external or median posterior artery {Fig. Ill, mp) ; it passes into the substance of the posterior column at the middle of the posterior root-zone, and on reaching about one-third the depth of the posterior column, it curves outwards to reach the posterior grey horn, where it terminates. Small vessels {Fig. Ill, g) pass from the pia mater of the posterior median fissure into the substance of the column of Goll. Another vessel, which may be called the artery of the posterior commissure {Fig. 1 11, pc), passes from the pia mater along the posterior margin of the posterior commissure, and winds backwards along the internal edge of the posterior horn. § 356. Growuing of the Ganglion Cells. — The ganglion cells of the anterior horns are arranged in groups which are pretty constant for the same portions of the cord, although the arrangement varies considerably when sections at different elevations are compared. A diagram of the topographical distribution of these groups is given in Fig. Ill, Beginning at the posterior and lateral aspect of the anterior horn, a group is observed which from its position is called the postero-lateral group (pi). It is bounded behind by the pos- terior and in front by the anterior twig of the median branch of the central artery ; while on its external aspect it receives branches from the median lateral artery, one of which passes behind and another in front of it. Anterior to this group is another, which from its position is called the antero-lateral group (al). On its external aspect the group receives branches from the anterior lateral artery, one of these passing behind and another in front of it, while a median branch of the artery may often be seen to pass into its substance. A branch from the external anterior root artery winds round its inner border to gain the posterior aspect ; while the anterior branch of the central artery passes along its internal and anterior aspects. It has already been mentioned that the internal and external anterior root arteries, on reaching the grey substance, divide 22 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. into two branches; and the external branch of the former and internal of the latter converge so as to meet at a point like the limbs of the letter V. In the small area of grey matter which lies between these vessels several distinct cells are so constantly observed as to deserve a special name. These cells may from their position be called the anterior group (a). Another group of large cells, which may be called the internal growp {i), is bounded anteriorly and internally by white substance, and on the external aspect by the anterior branch of the first subdivision of the artery of the anterior median fissure. Another group of cells may be observed towards the centre of the anterior horns, and it may therefore be termed the central group (c). It is bounded in front and on its internal and external borders by the external and internal branches of the external anterior root artery ; and behind and also on its internal border by the median and anterior branches of the central artery. A very important area lies between the internal group on the one hand and the antero-lateral and central groups on the other, while the anterior group passes into its anterior border, like a small wedgfe, so as to divide it into the form of the letter Y. The cells of this median area (m) are much smaller than those of the other groups, and the area itself is exceedingly vascular, being supplied by the two anterior root arteries^ the anterior branch of the first division of the artery of the anterior median fissure, and the anterior branch of the central artery. A final group of cells lies near the internal border of the posterior grey horn near the posterior commissure called the vesicular column of Clarke {vc). We must again direct attention to the fact i\iQ,i Fig. Ill is only a diagram; and although it is more like the upper part of the lumbar and lower portion of the cervical enlargements than any other part of the cord, yet it is not a strictly accurate representation of any one section. The dis- tribution of these groups at various elevations of the cord will be better understood after the history of the development of the grey substance has been sketched. § 357. Development of the Central Grey Tube. The parts which subsequently correspond to the anterior grey horns are the first portions of the cord to be developed. These are soon sue- ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. 23 ceeded hy lateral masses, and somewhat later by the posterior horns. The anterior grey commissure is then formed, and this is soon followed by the development of the posterior commissure, and it is only at a considerably later period that the white commissure appears. When the tube which forms the rudiment of the cord has closed, it is seen to be somewhat oval on section, and at this period it consists almost entirely of grey substance. The grey substance is at first composed of small round cells, not much larger than lymphoid corpuscles, with a distinct nucleus, and no difference can be detected between one portion and another ; the whole is simple and indefinite in its structure. A section of the cord at the third month of embryonic life {Fi^. 112) shows that the central canal has contracted to a small oval opening, covered by columnar epithelium, while the grey substance has assumed the general outline characteristic of the grey substance of the adult cord. The grey substance is also surrounded by a mantle of white substance, but we shall entirely neglect the history of the development of the latter in the meantime. Fig. 112. § 358. Development of the Anterior Orey Horns. The most noticeable feature about the grey substance at the third month is that the anterior grey horns are distinctly differentiated from the posterior horns, not simply in their general outline, but in their intimate structure. The groups of gan- glion cells are now beginning to be distinctly recognisable. Of these, the antero-lateral group is the most advanced in its development. Large, mostly round, cells, with a distinct nucleus, are observed embedded in the embryonic tissue ; but the cells have not yet assumed distinct processes. The small internal group is also well represented by several distinct large cells, but the cells are more elon- gated, and not quite so large or so distinct as in the antero-lateral group. A few cells may be observed in the anterior group. The postero-lateral group is represented by four or five large round cells, but the central group is not yet represented. The areas in which the median and central groups are subsequently developed, and the area which separates the antero-lateral and postero-lateral groups, are composed entirely of embryonic tissue, with small round cells. The vesicular column of Clarke can also be distinguished at this period, by a slight increase in the size of the cells in comparison with those of the surrounding tissue, but the group does not appear in the portion of the cord from which this section was taken. Fig. 112. Section from the middle of the Cervical Enlargement of the Spinal Cord at the third month of Embryonic Life. — C, Central canal. The other letters indicate the same as the corresponding letters in Fig. 111. 24 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. A still further advance in development is recognisable at the end of the fifth month of embryonic life (Figs. 113 and 1 14), The cells of the antero- lateral group have not only increased still further in size, but their pro- cesses are now well developed {.Fig. 114, 1), and each may be seen to lie in a distinct cavity. Those of the anterior and internal groups are also well developed, and the same may be said with respect to the cells of the centre of the postero-lateral group ; and even those of the central group are fairly well developed, although only two or three of them have as yet developed processes. The area in which the median group is subsequently developed, and the margins of the postero-lateral and central groups still consist of embryonic tissue. The larger cells of these areas are represented inFig. 114, 2. The section represented in Fig. 113 was taken from the middle of the cervical enlargement, and the vesicular column of Clarke is not represented ; but the cells of this column are fairly well developed at the fifth month in the lower end of the cervical enlargement and in the dorsal region and upper end of the lumbar enlargement. The section repre- sented in Fig. 114 was taken from the middle of the lumbar enlargement, and no trace of the postero-lateral group could be discovered ; but in the upper portion of the lumbar enlargement it occupies a similar position to Fig, 113. Fia. 114. I.*"^ ® 2 EiGS. 113 and 114 (Young). Sections of Spinal Cord of a Five Months Human Embryo, from the middle of the cervical and lumbar enlargements respec- tively. — i, internal; a, anterior; al, antero-lateral ; pi, postero-lateral, c, central, m, median, and groups of ganglion cells : 1, ganglion cell of the centre of the antero-lateral group ; 2, ganglion cell of median group ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 25 that which it occupies in the cervical enlargement, as represented in Fig. 113. The vesicular column of Clarke does not appear in the lumbar enlargement. The ganglion cells of the various groups have become still further deve- loped at the ninth month {Figs. 115 and 116) ; while by the development Fig. 115. Fia. 116. f3ic Figs. 115 and 116 (Young). Sections of Spinal Cord of a Nine Months Human Embryo, from the middle of the lumbar and cervical enlargements respec- tively. — A, anterior, and P, posterior horns. The small letters indicate the same as in Figs. 113 and 114. The normal size of the section from which the drawing was made is shown above each figure. of caudate cells in the central and postero-lateral groups the various groups have became so approximated as not to be so distinctly recog- nisable from each other as they were at the fifth month of embryonic ■life. The section represented in Fig. 115 was taken from the middle of the lumbar enlargement, and the postero-lateral group is not so well repre- sented as it is in the upper part of the lumbar region. The median area now contains distinct ganglion cells instead of consisting entirely of em- bryonic tissue. These cells are, however, not much larger than those of the antero-lateral group at the third month ; while they are by no means so well developed as those of the latter at the fifth month. The cells of the median group are small, angular masses with a distinct nucleus, but only a relatively small number of these have developed processes. It is not necessary to say much at present with respect to the adult cord. The most noticeable feature in which the cervical and lumbar enlargements of the adult cord differ from the corresponding parts of the cord of a nine 26 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. months embi'jo is in the fact that the ganghon cells of the median group have developed processes like those of the other groups. The cells of the median group, however, especially in the cervical enlargement, are not only much smaller than those of the other groups, but they are much thinner and more transparent. These cells are so transparent that they may be very readily overlooked altogether in sections cleared by oil of cloves, and mounted in Canada balsam ; while the cells of the antero- lateral group not only intercept the light, but require considerable change of focus, in order to bring their anterior and posterior surfaces clearly into view. The relationship which the developing cells bear to the distribution of the blood-vessels is exceedingly interesting. The earlier-developed cells appear to be thrust further and further away from the vessels as develop- ment advances. The postero-lateral group, for instance, first shows itself by the development of four or five large cells, which appear about the centre of the spot in which the completed group is subsequently situated ; and, as ganglion cell after ganglion cell becomes developed around this centre, the area becomes increased in size by the growth of additional embryonic tissue around the circumference of the group in the part which is in relation with the arterioles (Fig. 111). The ganglion cells of the centre of the group are the first to be developed, and the group increases in size by the gradual development of new cells around the central ones. The marginal cells of the group are consequently the last to be developed. Similar remarks apply to the ganglion cells of the central group, as well as to the antero-lateral, anterior, and internal groups, except that the last three groups, instead of being surrounded on all sides by grey substance, are on one of their sides in contact with white substance. § 359. The Accessory Nerve Nuclei of the Spinal Cord. (1) Median Area. — The comparatively late period in the development of the cord at which the ganglion cells of the median area of the anterior horns assume processes shows that this area must be regarded as an accessory structure (§ 33). The relatively large size of this area in the cervical, as compared with the lumbar enlargement, shows that it is a much more im- portant structure in the former than the latter region. In the fifth month of embryonic life the median area is not larger in the cervical than in the lumbar region, as shown in Figs. 113 and 114, where it will be seen that there is scarcely any difference in the general outline of the anterior horns in the sections from the middle of the cervical and lumbar enlargements respec- tively. In the embryo of the ninth month, however, the median area in the cervical is decidedly larger than in the lumbar enlargement {Figs. 115 and 116), and consequently the anterior grey horn in the former region is extended laterally to make room for this area. The relative increase in the size of the median area in the cervical enlargement of the human adult cord, as compared with that of the lumbar enlargement, is still more ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 27 marked than in the cord of a nine months embryo, as may be seen in Figs. 117 and 118, where the median area occupies a large space, and the lateral outgrowth of the anterior grey horn of the cervical region is very decided. On observing the large relative size of the median area in the cervical enlargement of the adult human cord, as compared with that of the lumbar enlargement, and even as compared with that of the cervical enlargement of the cord of the embryo, it occurred to me that this area might not Fig. 117. Fig. 118. Figs. 117 and 118 (Young\ Sections of the Adult Spinal Cord from the middle of the Lumbar and Cervical Enlargements respectively. — The letters indicate the same as those in Figs. 113 and ll4. possess any relative importance in the cervical enlargement of the spinal cord in animals. In order to test this conclusion I applied to Mr. Larmuth, of the Owens College, whose' beautiful sections of the spinal cord are well known in Manchester, and asked him if he would be kind enough to let me have sections of the lumbar and cervical enlargements, as well as from the middle of the dorsal region and the upper portion of the cer- vical region of the spinal cord of the ox. Mr. Larmuth, in kindly con- senting to let me have what I wanted, volunteered the statement that it was quite unnecessary to have a section of both the cervical and lumbar regions, as the two were so alike as to be indistinguishable, and both were like the lumbar enlargement of the human cord. This was, to a large extent, the very fact I was in search of. I have had an opportunity since that time of examining these sections more minutely A section from the cervical enlargement of a calf is represented in Fig. 119, and it 28 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. will be at once seen that the general outline of the grey substance is very like that of the grey substance of the lumbar enlargement in man, and the median area occupies a still smaller area in the former than in the latter. The median area, indeed, can scarcely be said to exist in the spinal cord of the calf, and this is also true with respect to the cord of the ox. (2) The, medio-lateral area lies between the antero-lateral and postero- lateral groups of ganglion cells, and it will be hereafter seen that it is a very important structure in the dorsal and upper cervical regions of the cord {Figs. 120 and 121, ml). The cells of this area are not well developed at the ninth month of embryonic life in these regions of the cord, and it is entirely unrepresented in the spinal cords of the ox and dog. Fig. 119. Fig. 119 (Young). Section of Cervical Enlargement of Calf.- the same as Fig. 113. -The letters indicate We have just noticed that the cells of the median and medio-lateral areas are not only developed at a comparatively late period of embryonic life, but that they are also much smaller in size than those of the other groups of the anterior horns. It might, therefore, be concluded that the size of a ganglion cell may be accepted as a true test of the time at which it began to develop. This test can, however, be relied upon only within certain very narrow limits. The cells at the margins of the postero- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 29 lateral group in the lumbar and cervical enlargements are nearly if not quite as large as those of the centre of the group, although the latter began to develoj) at a much earlier period than the former ; while the cells of the nuclei of origin of the third and fourth nerves are small, although they have begun to develop at a comparatively early period. The size of the cell may be accepted as a rough test of its age during the period of development, and no longer, just as the size of a growing human being may be accepted as a rough test of age until the adult condition is attained, when it ceases to be a test any longer. The size of the ganglion cells of the anterior horns of the cord of the adult appears to depend mainly if not entirely upon the size of the muscle over whose function it presides ; hence the cells of the nuclei of the third and fourth nerves are small, while the greater number of the cells of the cervical enlargement are large, and those of the lumbar enlargement are still larger. It frequently happens that the later- developed cells of the cord are small in the adult condition, but this is because the most special muscular adjustments are effected by the con- tractions of small muscles. § 360. Development of the Neuroglia. So far we have spoken only of the development of the ganglion cells, but we must now briefly refer to that of the neuroglia. In the early weeks of foetal life the neuroglia consists of small round nucleated cells, or rather of a nucleus surrounded by a layer of soft protoplasm, and with scarcely a trace of basis substance. As development advances, the protoplasm contracts round the nuclei, and the latter become embedded in a fibrillated, some say granular basis substance. The neuroglia becomes denser and more compact in proportion as it acquires more and more of the basis substance and loses its cellular character. This change does not occur in every part of the grey substance at the same time. Speaking broadly, the neuroglia assumes a fibrillated texture in the very portions of which the ganglion cells are earliest developed ; while it maintains its embryonic condition in the margins of the groups of ganglion cells of the anterior horns and along the line of the blood-vessels. And when a section of the adult cord is held up to the light the groups of large ganglion cells may be seen as dark spots inter- cepting the light, and strongly contrasting with the transparency of the median area and of the margins of the antero-lateral and postero-lateral groups along the lines of the vessels. The transparent portion also em- braces the anterior and posterior grey commissures and the central column of the grey substance as far back as the substantia gelatinosa, with the exception of the area occupied by the vesicular column of Clarke. The transparency of the area just described is no doubt due in some measure to the fact that the small ganglion cells themselves are more transparent than the large ganglion cells, but it is also in great measure due to the loose and spongy character of the neuroglia in the former areas as com- 30 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. pared with the compact and fibrillated texture of the neixroglia surrounding the ganglion cells of the earlier-developed groups. The transparency is increased by the fact that the larger vessels of the anterior horns pass along the transparent areas, while only the smaller vessels pass into the substance of the earlier-developed groups. § 361. Development of the Posterior Orey Horns The development of the posterior horns appears to proceed on a dif- ferent principle from that of the anterior horns. The vessel which is mainly distributed to the posterior horn passes into it through the centre of the posterior roots of the nerves, and the development of new substance proceeds mainly in the centre of the horn, so that the older-formed tissue is pushed out laterally. The central portion of the horn consists of what is called the substantia gelatinosa, and is made up in large part of neu- roglia and fibrils, in which medium-sized ganglion cells are embedded. The lateral portions of the horn contain well-formed and thicker nerve fibres. The most internal of these fibres pass through the posterior root- zones in order to gain access to the posterior grey horns, and these are called the inner radicular fasciculus (Charcot). The outer radicular fasciculus passes along the outer margin of the posterior horn, and between it and the pyramidal tract of the same side. It is therefore probable that the inner and outer radicular fasciculi contain the earlier-formed afferent fibres, and that consequently they preside over the earlier-formed and most fundamental functions. § 362. Development of the Central Orey Column. The central grey column appears to grow mainly round the central artery as a centre. The portion which immediately surrounds the central canal consists almost entirely of neuroglia ; but the anterior and lateral portions contain, in addition, nerve-fibrils and scattered ganglion cells, the latter being much smaller and not so distinctly caudate as those of the anterior horns. This portion of the grey substance contains a rela- tively large number of Deiter's cells, and the neuroglia is much more spongy than in the anterior and posterior horns. The posterior and inner part of the central column contains a group of large caudate cells— the vesicular column of Clarke. This group lies close to the internal border of the posterior horn, near the posterior commissure. It consists of neuroglia nerve-fibres and ganglion cells, the latter of which are bipolar, or at least not so distinctly caudate as those of the anterior horn. The neuroglia in which the cells are embedded is more dense and compact than that of the remaining portion of the central column, being in this respect similar to the neuroglia surrounding the cells of the groups of the anterior horns. With the exception of the vesicular column of Clarke, the central column appears to be the embryonic portion of the grey substance, the portion adjoining the central canal being the last formed, and consisting of scarcely anything but neuroglia. As a new layer of tissue grows ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 81 around the canal the central opening becomes smaller and smaller, and the earlier-formed layers are displaced away from the centre. The later-formed parts of the anterior and posterior horns grow at the expense of the central column. But the portion subtracted from the central column by each increment superadded to the anterior and posterior horns is replaced by the growth of a new layer of tissue around the central canal. The cells of the central column do not develop until a late period of embryonic life, and they may therefore be regarded as cells superadded, in the course of evolution, to those of the anterior and posterior horns, and of the vesicular column of Clarke, and rendered necessary by newly- acquired complications of movement. The group of cells which I have described as the median group of the anterior horn may, indeed, be regarded as an anterior outgrowth of the central column, its relatively large size in the cervical region being rendered necessary by the complicated move- ments of the hand. In addition to the ganglion cells and fibres belonging to the central column itself, it transmits a large number of intercom- municating fibres. § 363. Longitudinal Distribution of the Groups of Ganglion Cells. The remarks which have hitherto been made refer particularly to the development of the lumbar and cervical enlargements of the cord ; but a few words must now be said with respect to the distribution of the various groups of ganglion cells in the other portions of the cord. The grey substance of the dorsal region is represented in Fig. 121, where it will be seen that the most anterior portion of the anterior horn is occupied by three small groups of large ganglion cells. These groups cannot be so dis- tinctly distinguished in every section as they were in the one from which this drawing was taken; but indications of such a division may be found in most sections. These groups appear to corre- spond to the internal, antero-lateral, and central groups in the cervical and lumbar regions ; while the median group of small cells, which is so conspicuous in the cervical, is wholly unrepre- sented in the dorsal region. A very remarkable feature of the grey substance of the dorsal region is a comparatively wide area which lies between the aotero-lateral and postero-lateral groups, and which I have already named the medio-lateral area {Fig. 121, ml) ; it is filled with small ganglion cells, which have only developed processes towards the ninth month of foetal life. 32 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. On passing now to the upper cervical region of the cord, it will be observed that a transposition of the ganglion groups takes place somewhat similar to that which occurs in the dorsal region. Above the level of the fifth cervical vertebra the area of the median group of small cells rapidly diminishes in size, so that the antero-lateral approximates the internal group, and the small anterior, and probably also the central groups dis- appear. An area of small cells is, however, interposed between the antero-lateral and postero-lateral groups, which begins to show itself as low down as the sixth cervical nerve, and gradually increases in size to the upper end of the cord. There the median group disappears entirely, so that the internal and antero-lateral groups are only separated by a small vessel, while a considerable area of small cells lies between the antero-lateral and postero-lateral groups {Fig. 120 m?). The Fig. 120. Fig. 121. Tigs. 120 and 121 (Young). Sections of the AdaU Human Spinal Cord, from the upper cervical and dorsal regions respectively.— A, anterior, and P, posterior horns ; aa, anterior roots ; cc, central canal ; ml, the medio-lateral area. The other letters indicate the same as the corresponding ones in Figs. 113 and 114. The size of the sections from which the drawing was taken is indicated above each. In Fig. 121, w represents the vesicular column of Clarke. ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. 33 distribution of the different groups in the upper cervical region is, indeed, very similar to that which occurs in the dorsal region. It will, however, be seen, on comparing Figs. 120 and 121, that the central group is unrepresented in the upper cervical, while it is represented in the dorsal region, but this difference is unim- portant since I am not sure that the group is always absent in the upper cervical, or always present in the dorsal region. One important difference, however, exists between the dorsal and upper cervical regions of the cord, and that is the presence of the vesicular column of Clarke in the former and its absence in the latter. The vesicular column of Clarke begins at the upper end of the lumbar enlargement, where it consists of a group of large bipolar cells ; it is continued upwards throughout the whole of the dorsal region, although its cells are consider- ably smaller here than in the upper lumbar region, and it ter- minates in the lower part of the cervical enlargement. § 364. TJie Grey Substance of the Medulla Oblongata, Pons, and Crura Cerebri. In the upper segment of the spinal cord both the grey and white substances undergo extensive rearrangement. One im- portant alteration of the white substance is that the column of GoU increases in size by the addition of grey matter — the clavate nucleus — in its interior {Fig. 122, G, en), and at a little higher level the posterior root-zone also increases in size by the formation of the triangular nucleus in its substance {Fig. 122, pr, tn). The increased size of the posterior columns displaces the gelatinous substance of the posterior grey horns (Fig. 122, sg), so that they extend in a lateral direction instead of posteriorly as in the cord. Another rearrangement of the white substance is produced by the crossing of the lateral columns, so as to form the anterior pyramids of the medulla {Fig. 122, x, P). These fibres by their crossing cut off the anterior grey horns from the rest of the grey substance, while they thrust the commissures, the central grey column, and the central canal further towards the posterior surface of the medulla. The principal alterations of the grey substance, therefore, consist in the lateral displace- ment of the posterior horns, the slight posterior displacement of the central canal, central grey column, and commissures, and the D 34 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. detachment of the anterior horns from the central grey column. A careful examination, however, shows that one or two other minor but exceedingly important alterations have taken place. The triangular nucleus and, at a little higher level, the clavate nucleus {Fig. 122, tn, en) give off arcuate fibres, which are Fig. 122 ( Young). Section of the Lower End of the Medulla Oblongata on a level with the crossing of the fibres of the lateral column. A, Anterior grey horns, showing that the grey matter has become mixed up with the white substance of the anterior root-zone, and with arcuate fibres. i X al. Internal group and a portion of the antero-lateral group. ale, Anterior nucleus of the lateral column, being a portion detached from the antero-lateral group. pic, Posterior nucleus of the lateral column, being a portion detached from the postero-lateral group. sg, Substantia gelatinosa displaced laterally. at. Ascending root of the trigeminus. /, Fasciculus rotundus. vc, Vesicular column of Clarke ? P, Pyramidal tract, X, Crossing of the fibres. ar. Internal portion of the anterior root-zone. ar'. External portion of the anterior root-zone. XII, Hypoglossal nerve. XI, Spinal accessory nerve. Gr, The column of GoU — the slender fasciculus. en. The clavate nucleus. pr, The posterior root-zone— the cuneate fasciculus. tn. The triangular nucleus. cc. The central canal. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 35 directed forwards and upwards in a semicircular manner to reach the olivary body of the same side. These fibres pass through the posterior horns and thrust them still further in a lateral direction, and, indeed, almost entirely separate the greater portion of each horn with its substantia gelatinosa from the grey substance which surrounds the central canal. The arcuate fibres interlace with the fibres of the lateral columns as the latter bend forwards to cross, and also detach a portion of the antero-lateral and postero-lateral groups of cells, so that a portion of these groups now extends into the white substance of the anterior root-zones {Fig. 122, ale, pic). The continuation of the anterior root-zones {Fig. 122, ar and ar') of the cord through the medulla oblongata is broken up into a reticulated formation — i\iQ formatio reiicularis — first Fig. 123. Fig. 12.3 (From Henle's Anatomie). Formatio Reticularis of the Medulla Oblongata showing the ganglion cells distributed through it. 36 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. Fig. 124, Fig. 124 (Young). Section of the Medulla Oblongata on a level with the Glosso- X>haryngeal Nerve. P, Pyramid. X), Accessory portion of the pyramid. Xii, Hypoglossal nerve. Hj Nucleus of hyiDoglossal. The internal, antero-lateral, and postero-lateral groups. a, Anterior group of cells. IS, Glosso-pharyngeal nerve. ngp, Nucleus of glosso-pharyngeal. VIII, Lower part of the posterior median acoustic nucleus if. Internal accessory facial nuclei. ef. External accessory facial nuclei. ale, Anterior nucleus of the lateial column. pic. Posterior nucleus of the lateral column. /, Fasciculus rotundus. ip, Internal division of the inferior peduncle of the cerehelhxm ■ Gr, Column of Goll. en, Clavate nucleus. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 37 by the arcuate fibres of the triangular and clavate nuclei, and then by the arcuate fibres of the inferior peduncles of the cere- bellum, and the whole of this tissue is thickly studded with caudate ganglion cells, as represented in Fig. 123. Whether all these cells are the representatives of those detached by the arcuate fibres from the antero-lateral and postero-lateral groups of the cord is not known. The cells detached from these groups, however, aggregate into two more or less distinct groups in the lateral part of the formatio reticularis of the medulla. These groups may from their position be called the anterior and posterior nuclei of the lateral column of the medulla {Figs. 122, 124, and 125, ale, pic); while the terms antero-lateral and postero-lateral may still be retained to designate what I believe to be the upward continuations of the portions of the antero-lateral and postero-lateral (Fig. 109, al, pi) groups of the cord which have retained their connection with the grey matter that may be considered as representing the anterior cornua. § 365. Continuation of the Anterior Grey Horns of the Spinal Cord through the Medulla Oblongata, Pons, and Crura Cerebri. — This slight digression into the examination of the rearrangement of the white substance, which takes place in passing from the spinal cord to the medulla oblongata, appeared necessary in order fully to understand the redistribution of the groups of ganglion cells occurring in the medulla. At the lower end of the medulla portions of the antero-lateral and postero-lateral groups may be seen to extend laterally into the substance of the anterior root-zone, or into the lateral column of the medulla oblongata as it may now be called. jjr, Posterior root-zone. tn. Triangular nucleus. dc, The direct cerebellar tract lying on the surface of the posterior root-zone, and the ascending root of the trigeminus. at, Ascending root of the trigeminus. sg, Substantia gelatinosa. L, Posterior longitudinal fasciculus. ar, The portion of the formatio reticularis, which represents the internal division of the anterior root-zone of the spinal cord. ar', The portion of the formatio reticularis, which represents the external division of the anterior root-zone of the spinal cord. 0, Olivary body. np. Nucleus of the pyramid. po, Parolivary body. 38 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. From the anterior nucleus of the lateral column (Fig. 122, ale), fibres maybe observed proceeding inwards and passing between the antero-lateral and postero-lateral groups. Some of these fibres cross over and appear to be connected with the spinal accessory nerve of the opposite side. Others wind round the postero-lateral group to get to the spinal accessory nerve of the same side. From the posterior nucleus of the lateral column {Fig. 122, pic), fibres proceed inwards to reach the grey sub- stance, and wind backwards along the boundary line between the white and grey substance to reach the spinal accessory nerve of the same side. The nuclei of the lateral column, therefore, appear to give origin to some at least of the fibres of the spinal accessory nerve ; and we have only to suppose that the same arrangement is carried out as we ascend the medulla and pons in order to understand the origin of the motor fibres of the pneumogastric and glosso-pharyngeal nerves, those of a large part of the facial nerve, and of the motor root of the fifth. The arrangement of the fibres from the nuclei of the lateral column which pass out along with the glosso-pharyngeal nerve is represented in Fig. 124. The fibres from the anterior nucleus {Fig. 124*, ale) proceed backwards and inwards, and pass between what will be afterwards described as the antero-lateral and postero-lateral groups. I have not been able to assure myself that any of these fibres cross over to the opposite side, although this is probable ; but some of them may be distinctly observed to wind round the postero-lateral nucleus to proceed in the direction of the glosso-pharyngeal nerve. The fibres from the posterior nucleus {Fig. 124, pZc) proceed backwards and inwards, and on reaching the grey substance bend abruptly outwards along the edge of the white substance to reach the nerve. A similar arrangement may be observed, at a lower level, with respect to the pneumogastric and spinal accessory nerves. At a higher elevation the fibres from the nuclei of the lateral column proceed backwards and inwards, the majority of them (genu nervi facialis) wind round the nucleus of the sixth nerve, and proceed outwards to join the facial nerve. The fibres from the posterior nucleus of the lateral column {Fig. 126, pic) appear to me to pass backwards and to the outside of the nucleus of the sixth nerve to join the facial. The anterior nucleus of ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 39 the lateral column appears to terminate on a level with the origin of the facial nerve. Fibres, however, seem to pass upwards and backwards from this nucleus to join the motor root of the fifth nerve. In Fig. 127 the anterior nucleus of the lateral column of the medulla is not represented, but the fibres trans- versely cut at (r) shows that these have joined the others from Fig. 125. Fig. 12-5 (Modified from Flechsig). Section of the Medulla Oblongata on a level tvith the superficial origin of the Acoustic Nerve. E, VIII, Root of the acoustic nerve. VIII, Posterior median acoustic nucleus. VII i", Posterior lateral acoustic nucleus. H, Niicleus of the hypoglossal nerve. ip, Internal division of the inferior peduncle of the cerebellum. ep. External division of the inferior peduncle of the cerebellum. frs, Formatio-reticularis. a, Arcif orm fibres. The remaining letters indicate the same as the corresponding letters in Fig. 124. 40 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. a differeDt level, and I "believe that these fibres have ascended from the anterior nucleus of the lateral column. The motor nucleus of the fifth {Fig. 127, v) appears to be the continuation upwards of the posterior nucleus of the lateral column. The nucleus now lies close to the sensory fibres of the nerve, and its fibres, instead of winding backwards at first, as they do at a lower level, appear to pass outwards at once by the side of the sensory fibres. The groups of cells of the anterior horns may be traced upwards more or less distinctly to the nucleus of origin of the hypoglossal nerve. The hypoglossal nerve begins on a level with the upper limit of the crossing of the fibres of the pyramidal tract. The crossing of the fibres had detached the Fig. 126. \ BVti r yf '\7i\\ Fig. 126 (Modified from Erb). Transverse Section of the Pons on a level with the Abducens and Facial Boots, from a nine months embryo. — The right half repre- sents a section made a little lower than the left. P, Pyramidal tract ; p, accessory portion of the pyramidal tract; Tr and Tr', transverse fibresof the pons ; so, superior olivary body ; ale and pic, anterior and posterior nuclei of the lateral column respectively, representing the nucleus of the facial nerve ; EVll, root of the facial nerve ; vi', nucleus of the sixth nerve ; KVi, root of the sixth nerve ; at, ascending root of the trigeminus. B, The internal division of the peduncle of the cerebellum as it passes from the cerebellum ; L, posterior longi- tudinal fasciculus ; ar and ar', the upward continuation of the internal and external divisions of the anterior root-zone of the spinal cord ; t, fasciculus teres. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 41 anterior horns from the grey substance surrounding the central canal; but when the crossing is completed, these two portions again become united. The olivary body is, however, inter- calated, the whole of the grey matter is thrust further and further back until the posterior commissure disappears, and the central canal opens at the calamus scriptorius on the floor of the fourth ventricle. The nucleus of the hypoglossal nerve is often described as if its cells constituted one group. These cells are, however, distinctly arranged into several groups which correspond so closely with the arrangement of the groups in the anterior horns of the cord that I have no hesitation in regard- ing those of the former as continuations of the latter. An Fig. 127. Fig. 127 (Modified from Erb\ Transverse Section of the Pons on a level with the origin of the Trigeminus, from a nine months human embryo. — P, pyramidal tract ; p, accessory portion of the pyramidal tract ; Tr, Tr', transverse fibres of the pons ; at, ascending root of the trigeminus and gelatinous substance ; dt, descending root of the trigeminus ; r, root-fibres of the trigeminus cut transversely ; v, motor nucleus of the trigeminus ; v', middle sensory trigeminal nucleus ; RV, root of trigeminus ; C, roots of the fifth proceeding from the cerebellum ; L, Poste- rior longitudinal fasciculus ; ar and ar', upward continuation of the internal and external portions respectively of the anterior root-zone of the spinal cord. 42 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. internal, antero-lateral, and postero-lateral {Fig. 109, i, al, pi) group may be distinguished, and these appear to correspond to the groups of the same name in the cord ; while a large number of cells may be observed at the roots of the hypoglossal nerve {Fig. 109, a), which may be called the anterior group, and which corresponds to the anterior group in the cord. All that has been previously said with regard to the development of the groups of cells in the anterior horns of the cord applies equally to those of the hypoglossal nucleus. The central cells of the latter groups develop first, while the marginal cells develop last and close to the blood-vessels which ramify between the groups as they do in the cord. Fig. 128, Tig. 128 (Modified from Meynert). Transverse Section of the Pons on a level with the upper end of the Fourth Ventricle, from a nine months human embryo.— F, pyra- midal tract ; p, accessory portion of the pyramidal tract ; Tr, Tr', transverse fibres of the pons ; B, superior brachium of the pons ; L, posterior longitudinal fasciculus ; ar and ai-', upward continuation of the internal and external portions respectively of the anterior root-zone of the spinal cord; v', middle sensory trigeminal nucleus ; dt, descending root of the trigeminus ; iv, nucleus of the fourth nerve ; cc, aqueduct of Sylvius. ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. 43 It is not easy to trace the continuation of the groups of cells of the anterior horns of the cord beyond the nucleus of the hypo- glossal nerve, inasmuch as the groups become separated longitu- dinally by the transverse fibres of the pons. It is, however, pro- bable that the nucleus of the sixth nerve {Fig. 126, vi') represents the postero-lateral group, and the bending of the fibres of the facial nerve round the nucleus corresponds to the similar bend- ing of the fibres which issue from the anterior nucleus of the lateral column in the lower part of the medulla round the Fig. 129. Fig. 129 (Modified from Krause). Transverse Section of the Cms Cerebri on a level with the anterior pair of Corpora Quadrigemina, from a nine months embryo. — cc, crusta ; P, pyramidal tract ; p, accessory portion of the pyramidal tract ; LN, locus niger ; RN, red nucleus of the tegmentum ; L, posterior longitudinal fasciculus ; ar and ar', upward continuation of the internal and external portions respectively of the anterior root-zone of the spinal cord ; ill, third nerve ; III', nucleus of the third nerve ; iv, fourth nerve ; iv', nucleus of the fourth nerve ; _iv", crossing of the fibres of the fourth nerves to opposite sides ; dt, descending root of the trigeminus ; cc, aqueduct of Sylvius ; x, crossing of the fibres of the superior peduncles of the cerebellum ; pf, fasciculus of medullated fibres proceeding to the anterior pair of corpora quadrigemina. 44? ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. postero-lateral group to join the spinal accessory nerve. The postero-lateral group cannot be traced beyond the nucleus of the sixth nerve, and probably ceases there. The internal, an- terior, and antero-lateral groups are dislocated upwards, as a result probably of the longitudinal extension of the central grey tube, which is rendered necessary in order to provide accommo- dation for the large mass of the transverse fibres of the pons. These groups reappear in front of the aqueduct of Sylvius, and form the nuclei of the third and fourth nerves (Fig. 129, ill', iv'). The fourth nerve is in my opinion merely a portion detached from the third by the decussating fibres of the superior peduncles of the cerebellum, and thus compelled to seek its destination by an independent route. The fourth nerve, there- fore, appears to belong to the system of anterior motor nerves represented by the hypoglossal, sixth, and third nerves, and not to the "mixed lateral system" represented by the spinal accessory, vagus, glosso-pharyngeal, and fifth nerves. Although the facial is a purely motor nerve, it appears to belong at least in part to that lateral system. That the nucleus of the sixth on the one hand and that of the third and fourth on the other really belong to the same nucleus, and are only separated from one another by some structure being intercalated in the course of evolution, is rendered probable by the fact that the nucleus of the sixth is connected with a portion of the nucleus of the third of the opposite side by a distinct bundle of fibres (Duval). The fact that these nerves are so closely related in their functions affords further corroborative evidence in favour of this opinion. § 366. Continuation of the Posterior Gr^y Horns of the Spinal Cord through the Medulla Oblongata, Pons, and Crura Cerebri. — We have already seen that the substantia gelatinosa of the posterior horns was not only thrust out laterally, but also almost detached from the rest of the grey substance by the arcuate fibres, and we must now observe that it maintains this lateral and superficial position as high as the level of the point of emergence of the fifth nerve {Figsi. 124 to 127, at). It may, indeed, be said that this structure is continued upwards to the level of the opening of the aqueduct of Sylvius into the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 45 third ventricle, since the descending root of the fifth nerve appears to be a somewhat similar structure to the ascending root and gelatinous substance {Figs. 127 to 129, dt). The white substance of the ascending root appears to be the analogue of the posterior root-zones of the cord — a mere continuation upwards of these zones, after what belongs to the spinal portion of the central grey tube has terminated in the clavate nucleus. § 367. Continuation of the Central Column and the Vesicular Column of Clarke through the Medulla Oblongata. In the lower end of the medulla the central column becomes separated from the anterior horn by the decussating pyramidal fibres, and almost separated from the posterior grey horns by the lateral displacement of the latter. A bundle of transverse fibres still connect the central column and the posterior horns, and these separate so as to leave an interspace in which longi- tudinal fibres may be observed to ascend towards the medulla. These form a round bundle (Figs. 1 22 and 124, f), which reaches as far as the upper end of the glosso-pharyngeal nucleus, and has been called the " ascending root of the lateral mixed system " by Meynert, and the " respiratory fascicle" by Krause. In the dorsal region of the spinal cord the middle portion of the grey substance is represented by two columns on each side of the central canal — the vesicular column of Clarke, and the central column — but the column of Clarke is unrepresented in the lum- bar and cervical regions of the cord. It appears to me, however, that the vesicular column of Clarke again becomes represented m the lower end of the medulla. A group of cells may be observed near the posterior and internal margin of the central column in the lower end of the medulla {Fig. 122, vc), corre- sponding to the position occupied by the vesicular column of Clarke in the dorsal region ; and the cells of both groups mani- fest a tendency to be bipolar instead of multipolar, like those of the anterior horns. Assuming, therefore, that the group of cells in the middle portion of the grey matter in the lower end of the medulla is the upward continuation of the vesicular column of Clarke, and that the remaining portion represents the central column in the cord, we shall have no difficulty in tracing the disposition of these portions of grey substance in the medulla. 46 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. Immediately above the crossing of the pyramidal fibres, where the anterior horns are pressed backwards towards the central canal, the central column lies posterior to the groups of cells representing the anterior horns, and close to the central canal, while the representative of the vesicular column of Clarke lies external to the central column, and posterior to the groups representing the anterior grey horns {Fig. 130, xi). The nucleus which represents the vesicular column of Clarke con- tains pigmented bipolar cells, and constitutes the posterior nucleus of the spinal accessory nerve {Fig. 130, xi'). And when the central canal has opened into the floor of the fourth Fm. 130. Fia. 130 (Young). Section of the Medulla Oblongata, a little below the point of the Calamus Scriptorius, showing the groups of cells of the grey substance. Rxi, Fibres of origin of the eleventh or spinal accessory nerve. XI, Posterior nucleus of the eleventh nerve. xi', Accessory nucleus of the eleventh nerve. Rxil, Fibres of origin of the twelfth or hypoglossal nerve. a, i, al, pi, Anterior, internal, antero-lateral, and postero-lateral groups of cells respectively. ah, Accessory hypoglossal nucleus. if. Internal accessory facial nuclei. ef External accessory facial nucleus. C, Central canal. /, Fasciculus rotundus. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 47 ventricle, the representative of tlae vesicular column of Clarke is thrust backwards, and laterally so as to form the principal part of the nuclei of origin of the spinal accessory, vagus, and glosso-pharyngeal nerves, while the central column winds round the groups representing the anterior horns {Fig. 124, H), so as to lie internal, posterior, and external to them. The posterior portion of the central column is elevated into a ridge (funiculus teres) close to the median fissure in the inferior part of the floor of the fourth ventricle {Fig. 124, if). The central column is continued upwards, as a thin film of grey substance, on the floor of the fourth ventricle, and lying behind the fibres of origin of the facial {Fig. 126, t) and the fifth {Fig. 127, r); while in the upper end of the pons and crura it is represented by the grey matter which immediately surrounds the aqueduct of Sylvius {Figs. 128 and 129, cc). The characteristics of the central column are, as we have already seen, that its texture is spongy, rendering it transparent on section, and that its cells are comparatively late in their development. We saw reason, indeed, to regard the central column as being the embryonic part of the central grey tube, and that the portions of it which are first developed are thrust outwards as new layers grow about the central canal. If this be true, we may expect to find that any additional nuclei which may form in the medulla oblongata in the course of development will grow in the representative of the central column. This expectation is realised. Whether the spongy portion of grey substance, which lies internal, posterior, and external to the hypoglossal nucleus, be or be not the continuation upwards of the central column, several groups of cells may be observed in it which do not become developed until subsequently to the ninth month of embryonic life, and which do not appear to be represented in the spinal cord ; they may, therefore, be called the accessory nuclei of the medulla oblongata. These nuclei must be carefully distinguished from the nuclei of origin of the spinal accessory nerve. § 368. Accessory Nuclei of the Medulla Oblongata. (1) Accessory Nuclei of the Facial Nerve. — The first of these which I shall mention is what has been described by Dr. Lock- 48 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. hart Clarke as the inferior facial nucleus. This nucleus consists really of several small nuclei. Two of these, which may be called the internal accessory facial nuclei {Fig. 130, if), appear as two small round nuclei close to the inner side of the hypo- glossal nucleus and the central canal ; and when the canal opens on to the floor of the fourth ventricle, they are situated imme- diately beneath the ependyma of the ventricle, and close to the middle line {Fig. 124, if). Fibres from these nuclei ascend in the funiculus teres and enter the fasciculus teres {Fig. 126, t), through which they join the other fibres of the facial nerve. Another somewhat larger group of small cells is situated at first posterior {Fig. 126, ef) and then external {Fig. 124, ef) to the nucleus of the hypoglossal. The fibres which issue from it also join, I believe, the fasciculus teres, and the group may, therefore, be called the external accessory facial nucleus {Fig. 109, ef). The cells of these nuclei are small, and destitute of processes in a nine months embryo. (2) Accessory Nuclei of the Eleventh Nerve. — Two groups of small cells, which develop at a comparatively late period, may be observed lying behind the posterior nucleus of the eleventh nerve {Fig. 130, xi'). Meynert thinks that the cells of these groups are connected with commissural fibres which run behind the central canal, before it opens into the fourth ventricle. (3) Accessory Nucleus of the Hypoglossal Nerve. — The next most important nucleus of this category is one which I have constantly observed in the hypoglossal nucleus of one side only {Fig. 130, ah). As I have not marked my sections, I am at present unable to say whether it is found on the right or left side. This nucleus is of a round form, and appears as if it were surrounded by a layer of white fibres, arranged longi- tudinally, which separates it from the surrounding tissue. It contains a large number of very small caudate cells, each being not one-fifth the diameter of the cells of the hypo- glossal nucleus. The nucleus in some sections lies between the internal and external convolute of the nucleus of the hypoglossal; while at other times it is embedded in the sub- stance of the internal convolute, being then situated near the margin of the group {Fig. 130). This nucleus is almost entirely limited to one side, although faint traces of it may occasionally ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 49 be observed in the opposite side; it is scarcely recognisable on either side of the medulla at the ninth month of embryonic life. The most reasonable supposition with regard to it is that it regulates the movements of articulation, and that it is con- nected with the third left frontal convolution of the brain. § 369. Special Nuclei of the Medulla Oblongata and Pons. (1) The acoustic nuclei can scarcely be said to be repre- sented by any portion of the grey substance of the cord. These nuclei are four in number : — {a) The posterior median nucleus of the acousticus {Fig. 125, vili) comes in contact with the nucleus of the vagus, but is more superficially situated than that of the latter, and somewhat to the outer side of the glosso- pharyngeal nucleus. It occupies the whole space between the ala cinerea and inferior peduncle of the cerebellum up to the anterior border of the striae medullares. The posterior root of the acoustic nerve takes its origin chiefly from this nucleus, and passes out partly in superficial fasciculi (striae acousticae) and partly through the body of the medulla. (6) The posterior lateral acoustic, nucleus {Fig. 125, viii") is a grey nodule lying in the peduncle of the cerebellum, between the deep and superficial fibres of origin of the acoustic nerve. (c) The anterior tnedian acoustic nucleus belongs to the anterior roots of the acoustic nerve, and is situated anterior to the striae medullares. It occupies the external angle of the fourth ventricle, about the middle of the cerebellar peduncle.- {d) The anterior lateral acoustic nucleus appears like a prolongation of the posterior lateral acoustic nucleus, and is wedged in between the middle peduncle and the flocculus. It gives origin to the portio intermedia Wrisbergii. Some anatomists believe that the fibres which pass in the chorda tympani, and which confer taste on the anterior two-thirds of the tongue, are derived from the nerve of Wrisberg (Bigelow). It is also probable that one of the other nuclei — perhaps the posterior lateral acoustic nucleus — gives origin to the fibres supplied to the labyrinth, and is not connected with the purely acoustic fibres. 50 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. (2) The corpora quadrigemina and geniculate bodies are the nuclei of origin of the second or optic nerve ; but we are unable to say, in the present state of our knowledge, what structures constitute the nuclei of origin of the first or olfactory nerve. § 370. Superadded Grey Matter of the Medulla Oblongata and Pons. (1) The Clavate Nucleus. — The columns of Goll contain in the lower part of the medulla a nucleus of grey matter, which is from its form called the clavate nucleus {Figs. 122 and 124, en). It is a longitudinal pillar of grey substance, and produced the enlargement in the fasciculus gracilis, known as the clava. (2.) The triangular nucleus {Figs. 122 and 124, tn) is a grey nucleus enclosed in the cuneate fasciculus, the latter of which is the continuation upwards of the posterior root-zones of the cord. It is a longish grey body on the inner border of the cuneiform column, and enlarging as it ascends. The clavate and triangular nuclei extend to the posterior end of the postero- lateral acoustic nucleus. (3) The olivary body {Fig. 124, o) is situated in the lateral columns of the medulla, close to the anterior pyramid. In form it is like a bean or an almond, with the hilus directed inwards. It contains a number of small ganglion cells, and is in substance very similar to the corpus dentatum of the cerebellum. (4) The parolivary body {Fig. 124, po) is a band of grey matter which bounds the internal half of the posterior border of the olivary body. (5) The nucleus of the pyramid {Fig. 124, np) (internal parolivary body) lies opposite the pyramid, in front and to the inside of the olivary body. (6) The superior olivary body {Fig. 126, so) is a longish, grey column, situated in the pons in front of the facial nucleus. (7) The red nucleus of the tegmentum {Fig. 129, RN) of Stilling, or superior olive of Luys, is situated in the crus cerebri, between the crus and tegmentum, and is similar in structure to the olivary body. (8) The middle sensory nucleus of the trigeminus {Figs. 127 and 128, v') is also a superadded structure. This nucleus is situated in the substance of the afferent fibres of the trigeminus, ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 51 not far from their entrance into the pons. In structure it is somewhat similar to that of the ganglia of the posterior roots, and it may represent the ganglion of the descending roots, while the Gasserian ganglion represents that of the ascending roots of the nerve. § 371. Development of tJie White Substance of the Cord. The white substance is formed on the surface of the deeper grey substance. Soon after the tube which forms the rudiment of the cord has closed, it is seen to be somewhat oval on section, with a central canal. At this period the cord consists almost entirely of grey matter ; and by the appearance of lateral slits each lateral half becomes imperfectly divided into two parts, the anterior and posterior. In the human embryo a zone of white substance appears towards the end of the first month on the exterior of each of these parts ; and these may respectively be called the anterior and posterior root-zones {Fig. 1 3 1 , a, ^). The anterior portions Fig. 131. Fig. 131 (From Eolliker). Transverse Section of tht Cervical Part of the Spinal Cord of a Human Embryo of six weeks. — c, Central canal ; e, e', Its epithelial lining ; g. Grey substance ; ar. Anterior roots ; pr. Posterior roots ; a. Anterior root-scones ; 2^, Posterior root-zones. of what are afterwards the lateral columns of the cord develop as parts of the anterior root-zones, but the posterior portions do not begin to develop until about two weeks later. The portions last developed appear to belong to the posterior root-zones, and join them in the medulla to form the restiform bodies ; and Flechsig thinks that they pass directly to the cortex of the cerebellum, hence they may be called the direct cerebellar fibres of the lateral columns. At the end of the eighth week, then, the grey substance of the cord in the human embryo is covered anteriorly, posteriorly, and laterally by a 52 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. layer of white substance ; but at tbis period very remarkable cbanges take place. Two bundles of longitudinal fibres, one for each side, are inter- calated between the direct cerebellar fibres of the lateral columns and the posterior horns of grey matter. These bundles on being traced upwards are found to pass forwards at the lower end of the medulla, and after decussating with one another they push aside the anterior columns, and form the inner and larger portion of the anterior pyramids of the medulla; hence the fibres may be called the pyramidal fibres of the lateral columns (^Fig. 132, P, P'). About the same time analogous formations appear in the anterior columns, one on each side of the median fissure which separates the anterior root-zones. These bundles are very variable in size and form, but are generally wedge-shaped or elliptical ; they form the outer and lesser portion of the anterior pyramids of the medulla, but do not decussate with one another. They are called the columns of Tiirck, or of Lockhart Clarke ; and they may also be called the pyramidal fibres of the anterior columns {Fig. 132, T). At the same period at which these bundles begin to develop, somewhat similar formations appear between the posterior root-zones, one on each side of the posterior median fissure, and these are called the columns of GoU {Fig. 132, G). The anterior white commissure {Figs. 134 to 140, ac) also appears at the same time, that is, about the eighth week. A most important point to notice in connection with the development of the white substance is that the fibres when first developed are destitute of a medullary sheath, and only become Fig. 132, «■/?, r/7 — fie Fig. 132. Cord of Human Embryo at five months.— ah, ah', anterior horns of grey substance ; ph. ph', posterior horns of grey substance ; ar, ar', anterior root- zones ; pr, pr', posterior root-zones ; P, P', pyramidal fibres of lateral columns ; T, columns of Tiirck; G, columns of GoU; dc, dc', direct cerebellar fibres; c, anterior commissure. I ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 53 Fig. 133. meduUated at a later period of development. The law of development already stated might, indeed, have led us to anticipate that such would be the case. A correlated fact is that the fibres of the bundles which are first formed develop a medullary sheath at a time when the fibres of the later-formed bundles are non-meduUated. When the cord of a human embryo is examined at the end of the fifth month it will be found that the pyramidal fibres of the lateral columns, the fibres of the columns of Tiirck and of the columns of Goll, are non-medullated ; while the fibres of the anterior and posterior root-zones, and those of the cerebellar fibres of the lateral columns, are medullated. When a transverse section of the cord is examined iu glycerine after hardening in chromic acid, the bundles com- posed of the non-medullated fibres will be found to transmit the light more readily than those composed of the medullated fibres, so that the section exhibits the appearances represented {Fig. \Z2) in the cervical region of the cord of a human embryo at the fifth month. Even when examined by the naked eye after hardening in chromic acid the bundles composed of non-medullated fibres are seen to be of a much darker colour than the bundles constituted of medullated fibres ; and the former also become much more deeply stained with carmine than the latter. The bundles composed c^f the non-medullated fibres are, indeed, to the naked eye and in their reactions to staining fluids, more like the grey than the white substance of the adult cord. The Accessory Portion of the White Substance. — Inasmuch as the greater part of the fibres of the anterior and posterior root-zones, as well as those of the direct cerebellar tract, are me- dullated as early as the fifth month of embryonic life, it may be presumed that all of them are fully developed at birth. The case, however, is dif- ferent with regard to the fibres of the pyramidal tract, some of them being medullated and fully developed at the ninth month of embryonic life, while others are not. The fibres of the columns of Goll are probably also not all fully developed at birth. The fibres of the pyramidal tract in the cord are separated by the septse of neuroglia and the branching vessels into small lozenge-shaped spaces (i^i^r. 133). ^j^. 133, Transverse Section of a The later-formed fibres appear to in- portion of the Pyramidal Tract sinuate themselves from above down- rnagnified.-l Tihv^s of large diameter ; 2, fibres of small dia- wards along the margins of these meter; 3, Deiter's cells ; 4, twig spaces, so that the earlier-formed fibres ga5tt"^''oTttspUi:i ctd"" 54) ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. occupy their centres ; the older being therefore further removed from the blood-vessels than the younger fibres. It may be assumed that the earlier- formed fibres connect the cortex of the brain with the earlier-formed or fundamental ganglion cells of the anterior horns, while the later-formed fibres connect the cortex with the accessory cells. What has already been said with regard to the size of the ganglion cells as a test of the stage of Fig. 134. ar Fig. 134. Middle of Lumbar Enlargement. Section of Spinal Cord from the middle of the Lumbar Enlargement. — A P, anterior and posterior grey cornua respec- tively ; SG, substantia gelatinosa ; cc, central canal ; ac, pc, anterior and posterior commissure respectively ; G, column of GoU ; pr, posterior root-zone ; p, posterior root ; p', external radicular fasciculus ; p'r, internal radicular fasciculus; a, a, a, anterior roots ; ar, a?*', anterior root-zone; fr, formatio reticularis ; pt, pyramidal tract ; T, column of Tiirck, ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 55 development of the cell is equally true with respect to the diameter of the meduUated fibres. The diameter of these fibres may be accepted as a rough test of the age of the fibres during the period of development, but no longer. It is very probable that the small meduUated fibres of the pyramidal tract connect together the small cells of the anterior horns and relatively small cells in the cortex of the brain ; while on the contrary the thick fibres connect the large ganglion cells of the anterior horns and large cells of the cortex. The largest cells of the spinal cord, for instance, are found in the lumbar region, and the largest in the cortex of the brain in the paracentral lobule — the centre of the movements of the leg — and it is pro- bable that these cells are connected with each other by thick fibres. We Fig. 135. Upper end of Lumhar Enlargement. — The letters indicate the same as the corresponding ones in Fig. 134. have already seen that, as a rule, the accessory are smaller than the funda- mental ganglion cells of the anterior horns, and it may therefore be in- ferred that the accessory fibres of the pyramidal tract are as a rule smaller than the fundamental ones. The smaller fibres are found in greater numbers in the internal and posterior part of the lateral column, the portion of the white column which adjoins the grey substance. At this spot the septa of connective tissue are larger, the neuroglia is more 5Q ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. spongy, and the lozenge-shaped spaces already described (Fig. 133) are more distinctly marked than in the more external layers of the white substance. The formatio reticularis of the spinal cord appears indeed to owe its structural peculiarities mainly to the fact that it consists in great part of longitudinal fibres of small diameter separated into bundles by comparatively large septa of loose neuroglia. This portion of the cord also transmits fibres which issue from the grey substance to ascend in the pyramidal tract, and from the vesicular column of Clarke to pass out to the direct cerebellar tract. But the longitudinal fibres of small diameter, which are so abundant in this portion of the cord, would appear to belong to the accessory portion of the pyramidal tract. Indeed, the Fig. 136. Fig. 136. Lower end of Dorsal Region. — T, column of Tiirck ; dc, direct cerebellar tract. The other letters indicate the same as the corresponding ones in Fig. 134. spongy character of the neuroglia and the vascularity of this area render it peculiarly adapted for the growth of new fibres. The fibres of the columns of GoU are also separated by the distribution of the blood-vessels and septa of connective tissue into lozenge-shaped spaces. The fibres at the margins of these spaces are not meduUated at nine months of embryonic life, and they are as a rule less in diameter in the adult cord than the fibres which occupy the centres of the spaces. These small fibres must therefore be regarded as belonging to the accessory system. The fibres of the posterior root-zones are smaller than those of the anterior and lateral ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 57 columns, with the exception of some of the accessory fibres of the pyramidal tract. The reason of this appears to be that the fibres of the posterior root-zones connect the cells of the posterior horns with each other, and the latter being themselves small the intercommunicating fibres are also small. § 372. Longitudinal Distribution of the White Substance. These, then, are the component parts of the spinal cord, considered with reference to its transverse section ; the longi- tudinal distribution of these parts must now be described. Fig. 137. Middle of Dorsal Region. The grey matter extends the whole length of the cord, and its size maintains a constant relation to the number and variety of the movements to be co-ordinated ; hence it is larger in the lumbar and cervical regions, where the movements of the limbs are co-ordinated. The anterior and posterior root-zones also extend the whole length of the cord, and, speaking broadly, their size maintains a pretty constant relation to the 58 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. size of the grey matter, although there is probably a slight increase of size from below upwards. The most noticeable feature with regard to the remaining bundles of fibres is, that they increase steadily in size from below upwards. The fibres of Goll (Figs. 134 to 140, G) extend the whole length of the cord, but they gradually diminish in size from the medulla, so that mere traces of them are to be found in the lumbar region. The pyramidal fibres of the lateral columns {Figs. 134 to 140, 2^t) also extend the whole length of the cord, but steadily diminish Fia. 138. Fig. 138. Upper end of Dorsal Begion. in size from above downwards, so that they are reduced to comparatively small bundles in the lumbar region. The direct cerebellar fibres of the lateral columns {Figs. 136 to 140, dc) appear in the cervical region as thin lamellae of fibres, one on each side, external to the pyramidal fibres. They diminish in size from above downwards, and disappear somewhat below the middle of the dorsal region, so that in the lower dorsal and ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 59 lumbar regions the pyramidal fibres come to the surface of the cord. The fibres of Turck {Figs. 136 to 140, T) also diminish in size from above downwards, and disappear about the middle of the dorsal region. The relative size and position of the different segments of the white substance may be seen in Figs. 134 to 140, which Fig. 139. Fig. 139. Middle of Cervical Enlargement. represent sections of the spinal cord of a nine months human embryo at different elevations. The fibres of the pyramidal tracts (pt) of the lateral columns, and of the columns of Goll (G) and of Tiirck (T), have assumed a medulla at the ninth month, and are not, therefore, so distinctly marked off from the remaining portions of the white substance as they are 60 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. represented in the figures, the latter being in this respect more like the appearances presented by the cord between the fifth and sixth months of embryonic life, at a time when the fibres of the anterior and posterior root-zones and the direct cerebellar tract are alone medullated. Fig. 140. Section on a level with the Second Cervical Nerve. — sa, Spinal accessory nerve. The other letters indicate the same as the corresponding ones in Figs. 134 and 136. § 373. Continuation upward of the various Segments of the White Substance of the Cord through the Medulla, Pons, and Cms Cerebri. (1) Columns of Goll and Posterior Root-zones. — A trans- verse section of the lower half of the medulla shows that the columns of Goll are continued upwards into the medulla ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. 61 in the form of two bundles of fibres, one on each side of the posterior median fissure. Each bundle contains a nucleus of grey matter, which from its form is called the clavate nucleus, and the bundle itself is called the pyramidal column, or fasciculus gracilis (Fig. 122, G, en). External to this fasciculus is placed a wedge-shaped bundle, called the fasciculus cuneatus, holding in its interior a grey nucleus, called from its form the triangular nucleus (Fig. 122, pr, tn). The greater portion of the fibres of the posterior root-zone of the cord terminates in the cuneate fasciculus and its enclosed grey nucleus. The slender and cuneate fasciculi of the medulla are much larger in size than the column of Goll and posterior root-zone of the cord, owing to the interposition of the grey nuclei ; hence the posterior horn of grey matter is displaced outwards and forwards in the medulla, so that the continuation of the gelatinous sub- stance forms a mass of grey matter on the lateral aspect of the medulla, known as the grey tubercle of Rolando (Fig. 122, sg). This mass of grey matter is continued upwards in the medulla and pons to the level of the point of emergence of the fifth nerve, and gives origin to the ascending root of the latter. In close relationship with the external surface of this grey mass is a bundle, the fibres of which are medullated in a nine months embryo. This bundle is the homologue in the medulla of the posterior root-zone of the cord, and is frequently found diseased in locomotor ataxy (Figs. 122 to 127, at). One of the most remarkable rearrangements of fibres in the medulla arises from the fact that the cuneate fasciculus, through the intermediation of its nucleus, resolves itself into arcuate fibres, which pass forwards and upwards to be connected with the nucleus of the olivary body on the same side; and it is also probable that the slender fasciculus through its nucleus has a similar termination. A transverse section of the upper part of the medulla shows that the fibres have undergone a still further rearrangement, and that they are greatly reinforced in number ; but the course of the additional fibres will be more readily traced if we follow them from the cerebellum to the medulla, instead of from below upwards. (2) ConTiections of the Peduncles of the Cerebellum with 62 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. the Medulla Oblongata, Pons, and Crura Cerebri. — The in- ferior 'peduncle of the cerebellum, according to Stilling, breaks up, on entering the medulla, into an internal {Fig. 125, ep) and an external {Fig. 125, iii) division, the latter of which he called the "restiform body." The fibres of the internal division spring from the roof-nuclei of Stilling, and on reaching the medulla resolve themselves into arcuate fibres, which pass downwards and inwards, interlacing with the ascending fibres of the anterior root-zone behind the olivary body of the same side ; and some anatomists believe that they cross the median raphe to reach the olivary body of the opposite side. The fibres of the restiform body are derived from the cortex of the cerebellum, and from a layer of fibres surrounding the dentate nucleus ; and this division, on descending to the medulla, sub- divides into two bundles, which are separated from one another by the direct cerebellar fibres of the lateral columns of the cord in their ascent towards the cerebellum {Fig. 125, dc). In a nine months human embryo the fibres of the restiform body are non-medullated {Fig. 125, ep) ; while those ascending from the lateral columns are medullated {Fig. 125, dc), so that the two sets can be readily distinguished from one another. The fibres of the restiform body, like those of the internal division of the peduncle, resolve themselves into arcuate fibres ; the external bundle forming the zonular layer which passes in front of the olivary body, and the fibres of which reach the median raphe by passing both in front and behind the anterior pyramid. Those which pass in front of the anterior pyramid are called arciform fibres {Fig. 125, a) ; they wind backwards to reach the median raph^ {Fig. 141), where, after ducussating with the correspond- ing fibres of the opposite side, they bend outwards to reach the olivary body of the opposite side where they terminate. A great part of the arcuate fibres of the internal bundle seem to pass through the olivary body of the same side without being connected with its grey substance ; and after gaining the raphe they also cross over to pass into the interior of the olivary body of the opposite side, in the grey substance of which all the arcuate fibres of the restiform body terminate. The olivary body, therefore, is the medium of communication between the cuneate fasciculus and probably also the slender fasciculus of ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 63 the same side on the one hand, and the restiform body and probably the internal division of the cerebellar peduncle of the opposite side on the other hand. The fibres of the middle peduncle of the cerebellum are derived from the cortex ; they pass in front of and through the substance of the pons {Figs. 126 to 128, Tt and Tr'), where they separate the ascending fibres of the anterior pyramids into bundles {Figs. 126 to 128, P, p), and interlace in the middle line with the fibres of the middle peduncle of the opposite side. On reaching the opposite side they are supposed to terminate in the cells of interposed grey matter, by means of which they are connected with fibres descending from the crusta. The close relationship of the middle peduncles with the lateral lobes of the cerebellum is well illustrated by the fact that in those animals in which the latter are deficient or absent the transverse fibres of the pons are few or entirely wanting. Fig 141. ^'^y FtG. 141 (Prom Henle''s "Anatomle"). hiayrmn of a horizontal stction of the anterior part of the median rctph4qf tliie Medulla OMcngata. — Fpy, Anterior pyramid j Fba, Fibrse arciformea. 64 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The fibres of the superior peduncles are derived from the dentate nuclei ; they decussate with one another in the tegmentum, the fibres of one side passing over to be connected with the red nucleus of the opposite side {Fig. 129, x). The fibres of the superior peduncles are medullated in a nine months embyro ; they may be seen surrounding, and even in, the substance of the red nucleus {Fig. 129, RJ^T), and a con- siderable proportion of them pass upwards uninterruptedly into the tegmental portion of the internal capsule, and either end in the inferior or external surface of the thalamus, or, as I am inclined to believe, pass uninterruptedly along its external border upwards to be connected with the central convolutions of the cortex of the cerebrum. Some anatomists think that part of the fibres of the anterior root-zones pass through the crusta to join the lenticular nuclei; but a very important fact has been ascertained by Flechsig, which renders this doubtful. Flechsig found that in a nine months human embryo the pyramidal fibres in the crusta are the only ones which have acquired a medullary sheath ; and my own sections confirm this {Fig. 129, P). But the fibres of the anterior root-zones in the cord are medullated at a very early period of development, and long before the pyramidal fibres have acquired a medullary sheath ; hence it may be inferred that none of the fibres of the anterior root-zones pass up into the crusta or niotor tract of the crura, although it is very probable that new fibres become developed, which connect the corpora striata and the cord, and that these pass through the crusta and become mixed with the fibres of the anterior root- zones. The close connection which is maintained between the anterior root-zones and that portion of the central grey tube which is in immediate relation with the efferent nerves, seems to indicate that the former consist of fibres which co-ordinate the various segments of the cord longitudinally ; and there are other grounds for believing them to consist of a series of looped fibres which originate and terminate in the anterior part of the central grey tube. (3) The direct cerebellar fibres are represented by a thin lamella of longitudinal fibres lying on the surface of the cuneate fasciculus and of the grey tubercle of Rolando {Figs. 124 and ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 65 125, dc). They pass upwards to the cortex, and thus form an uninterrupted connection between its grey matter and the cord, where the fibres are supposed to pass inwards between the bundles of the pyramidal fibres of the lateral columns, to terminate in the cells of the group known as Clarke's column. Their function, however, is not yet ascertained. (4) Tlie Pyramidal Tract. — The pyramidal fibres of the lateral columns at the upper end of the cervical region of the cord pass forwards and inwards towards the anterior median fissure. These fibres decussate with one another in the medulla, so that those of the right side pass to the left, and those of the left to the right. The decussation frequently begins in the upper portion of the cord; while the homologues of the pyramidal fibres, which arise from the nerve-nuclei of the hypoglossal and facial nerves, cross separately in the pons above the decussation of the pyramids. The pyramidal fibres of the lateral columns during and subsequent to their decus- sation come forwards into the anterior median fissure, and push aside the columns of Tiirck {Fig. 140, T), so that the latter form a prismatic bundle of fibres external to the former, and ascend without decussating with one another. These two sets of fibres constitute the anterior pyramids of the medulla {Figs. 122 to 125, P) ; they can be traced through the pons {Figs. 126 to 128, P), where they receive a large accession to their size, into the peduncles of the cerebrum. According to the researches of Flechsig, which my own sections confirm, the pyramidal fibres, after being separated into distinct bundles in the pons, come together so as to form one compact bundle in each peduncle {Fig. 1 29, P). This bundle occupies about the middle third of the crust of the cerebral peduncle, and, contrary to what has hitherto been believed, it passes into the posterior segment of the internal capsule, lying between the lenticular nucleus and optic thalamus opposite the middle third of the latter. The pyramidal bundle is separated from the caudate nucleus by a layer of fibres, which ascend from the external surface of the optic thalamus to reach the corona radiata, while it rests on the three successive segments of the lenticular nucleus, and reaches the corona radiata opposite the third quarter of the caudate nucleus (reckoning from before F . 66 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. backwards). Having emerged from between the basal ganglia, without anywhere communicating with them, the fibres of the pyramidal bundle radiate in all directions towards the surface of the cerebrum, and are mainly distributed to the central convolutions about the sulcus of Rolando, the so-called " motor area" of the cortex (Fig. 142, P"). Fig. 142 'After Flechsig). Diagram of the Grey Masses of the Spinal Cord and Brain, showing the course of the Conducting Paths. It, Fissure of Rolando. P" P, T and Ft, Course of the fibres of the pyramidal tract from their origin in the central convolutions to their termination in the anterior grey horns (a, a'). ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 67 The cardinal facts which concern us at present are, that fibres issue from the central convolutions of the cerebrum, which pass through the internal capsules without communicating with the basal ganglia ; that the same fibres pass through the cerebral peduncles to enter the pons, where they at once begin to diminish in number. The fibres of this kind, which pass through the pons, collect together to form the anterior pyramids of the medulla, which also diminish iu size from above down- wards, showing that some of these fibres are lost in the medulla itself The internal and by far the larger portion of the pyramids decussate with one another, and these portions pass backwards so as to form in the cord the bundles of pyramidal fibres in the lateral columns — bundles which extend the whole length of the cord, but gradually diminish from above down- wards. The external and lesser portion of the pyramids pass directly downwards to form the columns of Tiirck — columns which dwindle gradually until they disappear, usually about the middle of the dorsal region. It is not yet proved anatomically how these fibres end in the cord ; but other considerations render it probable that they end in the grey matter of the anterior horns and its continuation through the medulla, pons, and around the aqueduct of Sylvius. The pyramidal fibres, in one word, form an uninterrupted connection between the central convolutions of the brain and the central grey tube of the cord. /, //, ///, First, second, and third portions of the lenticular nucleus (NL'. NC, Caudate nucleus. Th, Optic thalamus. D, C, B, A, Points from which fibres issue connecting the cortex of the brain and basal ganglion, and also the grey substance of the pons (PO). Bd, Fibres connecting the cerebellum and optic thalamus ; and Cap, those connecting the cerebellum and the grey substance of the pons. aq, &n.di pq, Anterior and posterior pair of corpora quadrigemina respectively. X, Upper, and x', lower fibres connecting the olivary body and the corpora quadrigemina. FR, Formatio reticularis of the medulla oblongata, formed by fibres from the optic thalamus [Th], the internal division of the inferior peduncle of the cerebellum [icp), from the spinal cord (fr, ar, and a/), and probably also from the clavate nucleus {Nc). o, Olivary body ; ecp, Fibres of the restiform bodies connecting the olivary bodies and cerebellum ; other fibres connect it with the triangular (Npr) and clavate (NC) nuclei. (IP, Decussation of the pyramids. pr'. Fibres of the ijosterior roots which pass upwards and downwards into the grey substance, and pursue only a short course. a, a', a", a"', a"", Anterior roots. p, pr, pr', pjr", G, Fibres of the posterior roots. 68 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The Accessory Portion of the Pyramidal Tract. — We have seen that the accessory fibres of the pyramidal tract occupy the margins of the lozenge-shaped spaces into which the lateral column and column of Turck are divided (i^^^. 183), and that they are very abundant in the portion of the lateral column which adjoins the grey substance, and especially in the formatio reticularis. But on ascending to the anterior pyramid of the medulla the accessory fibres become much more abundant, and Fig. 143. Fig. 143. (After Flechsig). Diagram of Transverse Section of the Spinal Cord in upper Imlf of the Dorsal Region. C, Anterior commissure. M, Fibres which pass from the vesicular column of Clarke 'vc) to the direct cerebellar tract. P, Posterior horn. Figs. 142 and 143 (After Flechsig).— Letters common to Figs. 141 and 142. Pt, Pyramidal tract of the lateral column. T, Columns of Tiirck. dc, Direct cerebellar tract. ar. Internal portion of the anterior root-zone. ar', External portion of the anterior root-zone. pr. Posterior root-zone. G, Goll's columns. fr, Reticular formation of the spinal cord. a, Anterior grey horns of the spinal cord. I ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 69 although some of them may still mix with the other fibres, they aggregate in the internal and anterior margin of the pyramid, so as to occupy a circumscribed area of the pyramid without admixture with other fibres. This area is shown in Figs. 124 and 125, p, which represent sections of the medulla of a nine months embryo. On passing through the pons the non- medullated fibres occupy the inner portion of the longitudinal fasciculi {Figs. 126 to 128, p), pass to the inner side of the medullated fibres in the crust of the crus cerebri (Fig. 129, p), and reach the cortex mainly by passing through the anterior half of the internal capsule. (5) The Anterior Root-zones. — The continuation of the anterior root-zones through the medulla, pons, and crus, deserves special attention. The course of the fibres of these zones in the medulla is obscured by the fact that they do not form a defined mass, as in the cord. They are separated into bundles by the arcuate fibres of the medulla, so as to form what is called from its reticular appearance the formatio reticularis (Fig. 125, frs). The zones consist of two portions, an internal, which lies between the anterior median fissure and the anterior roots (Figs. 134 to 140, ar), and an external, consisting of the remaining portion {Figs. 134 to 140, ar'). The internal portions of the anterior root-zones are pushed aside in the lower part of the medulla by the decussating fibres of the pyramidal tract, but above the level of the decussation, where the olivary body is intercalated, the internal portion is thrust backwards behind the pyramids and close to the median raphd, while the fibres of the hypoglossal nerve separate the internal from the external portion of the anterior root-zone. In the spinal cord the internal portion of the anterior root-zone maintains a close relation to the internal group of ganglion cells, and this relation is apparently maintained throughout its course in the medulla, pons, and crus. The portion which is called the posterior longitudinal fasciculus in the medulla {Figs. 124 to 128, L), pons, and crus, appears to be the con- tinuation upwards of the part of the internal portion of the anterior root-zone which adjoins the grey matter, and this fasciculus always lies to the inner side of the roots of the anterior motor nerves, at their origin in the motor ganglion 70 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. cells. The upward continuation of the part of the internal portion of the anterior root-zone which is remote from the grey matter is represented by ar in Figs. 124 to 129. In the crus the posterior longitudinal fasciculus is situated in front of the aqueduct of Sylvius, in close relationship with the nucleus of origin of the third nerve (i^i^. 129, Z). A portion of this bundle is continued forwards in the thalamus in the walls of the lateral ventricle, while the remaining fibres bend backwards to join the posterior commissure of the third ventricle. The fibres of the latter portion are the first to become medullated in the cerebrum of the human embryo. The external portion of the anterior root-zone of the cord is continued upwards into the formatio reticularis of the medulla {Figs. 12-i to 128, ar'). The continuation of the external portion of the anterior root-zone lies behind the olivary body, and comes to the surface of the medulla in its lateral column. It is bounded internally by the root fibres of the anterior motor nerves, and externally by the root fibres of the nerves of the lateral mixed system, and posteriori)'- by grey matter. The interlacing fibres of the pons {Figs. 126 to 128, Tr) pass in front of this portion (ar'), while in the crus the latter comes again further forwards, the locus niger lying between it and the crust {Fig. 129, ar). (III). -FUNCTIONS OF THE SPINAL CORD AND MEDULLA OBLONGATA. It would occupy too much space to describe fully the func- tions of the spinal cord and medulla oblongata, and the reader is referred to physiological manuals for the usual information on the subject. My main object at present is to elicit a few points which will be of subsequent use to us in interpreting the phenomena of disease, and in connecting symptoms with morbid alterations of structure. § 374. Voluntary Action. — The special functions of the cord are those by which the spinal centres are subordinated to the motor centres of the cortex of the brain. It is probable that all the spinal centres are connected with the motor centres of the cortex of the brain, or are, in other words, under voluntary ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 71 control ; but the later-acquired movements of man are more thoroughly under voluntary guidance than the earlier-acquired or fundamental actions. Inasmuch as the observation of the development of the cord has enabled us to draw a broad dis- tinction between the fundamental and accessory portions of the structure of the spinal cord, it will be well to endeavour first to connect the later-acquired or accessory functions with the later- acquired or accessory structure. The earlier-acquired or funda- mental functions will then be left as a residuum to be con- nected with the fundamental structure of the cord. (1) The Accessory Functions of the Spinal Cord and Medulla Oblongata. The movements of the hand afford the best example of the accessory- functions of the spinal cord. These movements are peculiar to man, and by far the greater number of them are acquired after birth. It may, therefore, be expected that the development of the structure, which represents these movements in the spinal cord, must also take place after birth. The movements which are most characteristic of the upper ex- tremity in man are those of pronation and supination of the forearm and the complicated movements of the hand and fingers, and it is exceed- ingly probable that the structural representatives of some if not all of these movements are to be found in the median group of cells. These cells appear at a late period of the development of the cord, hence they form a speciality of structure which corresponds to some speciality of function ; again they maintain a small size even in the adult cord, and consequently may be expected to preside over the action of small muscles, both of these conditions being realised in the hand. The smaller median area in the lumbar enlargement of the cord presides probably over the movements of the lower limbs, which dis- tinguish the adult man from the lower animals and also from the human infant. These movements are mainly executed by the extensors of the leg on the thigh and probably also by the adductors, and by the flexors of the foot on the leg. Indeed, the slight elevation of the ball of the toe, so as to allow the passive leg to swing forwards by its own weight in walking, is the last movement acquired by the child ; and we shall subsequently sse that it is the first movement to be affected in disease. If, then, the median area of small cells be the structural correlative of the later-acquired and more special movements of the limbs, it must be absent in those por- tions of the cord which do not supply nerves to limbs, and we have already seen that this area is absent in the dorsal and upper cervical regions of the cord. Tt must be remembered that the muscles of the hand are connected with the earlier-formed or fundamental cells of the anterior horns, and 72 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. that the small cells of the median area do not of themselves suffice for the regulation of their movements. The increased development of the median area in the cervical enlargement represents merely a com- plication on the previous structure of the cord corresponding to the complication of muscular adjustments vrhich distinguishes the hand of man from the anterior extremity of animals. The hypoglossal accessory nucleus, and the internal and external accessory facial nuclei, appear to be the homologues in the medulla oblongata of the median area in the cervical and lumbar enlargements of the spinal cord. The hypoglossal accessory nucleus seems to be the additional structural complication rendered necessary by the compli- cated movements executed in the production of articulatory speech ; while the facial accessory nuclei are the structural counterparts in the medulla of the movements of facial expression. The next accessory function which I shall mention is the muscular adjustments necessary for maintaining the erect posture in man. These adjustments are also acquired a considerable time after birth, hence it may be inferred that their structural counterpart in the cord is not well developed at birth. The medio-lateral area corresponds in my opinion to these adjustments in the dorsal region of the cord. The cells of this area are not well developed at birth, and the area is entirely absent in the lower animals. These cells are also of small size, even in the adult cord, and if, as we have already stated, the size of the ganglion cell is related to the size of the muscle with which it is connected, the erectores spines are the muscles of the trunk which best correspond to this description. The medio-lateral area appears also in the upper cervical region, and it may be presumed that the small muscles which extend the vertebral column in the neck, and draw back and rotate the head, are supplied from these cells. We have already seen that some of the fibres of the eleventh nerve (spinal accessory) are derived from the postero-lateral group in the cord, and it is very probable that the accessory nucleus of this nerve in the medulla is the homologue of the medio-lateral area in the upper cer- vical and dorsal regions of the cord. The accessory nucleus of the eleventh nerve is the additional organisation rendered necessary by the complicated movements of the human larynx. The marginal cells of the postero-lateral, antero-lateral, and central groups appear late in the development of the cord, and these therefore must be regarded as belonging to the accessory system, even although the ganglion cells are of comparatively large size. The fact that these cells are of large size shows that they must be engaged in the regulation of the movements of large muscles. It is probable that these marginal cells in the lumbar region regulate the contractions of the large muscles of the lower extremity which are engaged in maintaining the erect posture. The great relative size of the gluteus maximus in man, as compared with the lower animals, would appear to render necessary a corresponding increase in the number of ganglion cells ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 73 of the spinal nucleus which regulates its movements in the former, as com- pared with that in the latter. And inasmuch as the gluteus maximus is not much called into action until a considerable time after birth, these super- added cells must belong to the accessory system. These additional cells may probably be represented by the marginal cells of the postero- lateral group in the lumbar region. The alternate upward rotation of the pelvis which takes place in walking, and which is mainly effected by contraction of the gluteus medius and minimus, is likewise a very special movement ; and it also may be regulated by the later-developed cells of one or other of these groups of ganglion cells in the anterior horns. We have seen that the postero-lateral group in the upper cervical region gives off" the spinal portion of the spinal accessory nerve, and that this portion forms the external branch of the nerve, which is distributed to the sterno- cleido mastoid muscle and the upper portion of the trapezius. But in man the sterno-cleido mastoid is in close relation with the clavicular portion of the pectoralis major, being only separated from it by the clavicle, and in those animals in which the clavicle is deficient it runs with the anterior part of the trapezius muscle into the deltoid, forming a mastoido-humeral muscle. All of these muscles are closely associated in their actions, and it is, therefore, probable that all are innervated from the postero- lateral group, while the latissimus dorsi, rhomboidei, and several other muscles may perhaps be added to this list. It is very probable indeed that the muscles which may be compendiously summed up with reference to their functions as the accessory muscles of inspiration are innervated from this group in the cervical and dorsal regions. These muscles are briefly the sterno-mastoids and scaleni, the pectoralis major and minor, the serrati postici et superiores, the subclavius, and the elevators of the head and spinal column. The postero-lateral and medio-lateral groups of ganglion cells consist of a series of superimposed ganglionic centres, constituting a column of cells which extends from the lumbar region, through the dorsal and cer- vical regions of the cord to the medulla and pons. Speaking broadly, this column regulates the muscular contractions necessary for the main- tenance of the erect posture, the contraction of the extraneous muscles of respiration, in part at least that of the muscles supplied by the spinal accessory, vagus, glosso-pharyngeal, seventh, and by the motor branch of the fifth nerves. The portion of the facial nerve supplied by the continuation of the postero-lateral' group in the medulla probably pre- sides over the function of the facial muscles in their relation with mastication and respiration. The series of superimposed .ganglionic centres of which the postero-lateral group consists cannot act inde- pendently of each other; and in order to secure harmony of action, some of these centres must become subordinate to other centres, either of the same column or of some other part of the nervous system. All of them are doubtless co-ordinated in the cortex of the brain, but it is not improbable that the inferior centres of the column are also subordinated 74 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. to one of the superior centres in tlie medulla oblongata. If such should be the case, there is no occasion for assuming the existence of a distinct respiratory centre in the medulla oblongata apart from the upward con- tinuation of the postero-lateral column of cells. It is much more pro- bable that the respiratory centre is merely an enlargement in the medulla of the postero-lateral column of cells. It is also quite likely that this en- largement is closely connected with the other groups of cells which have been continued upwards from the cord into the medulla. (2) Fundamental Voluntary Functions. — With respect to the functions of the antero-lateral group, I must content myself by saying very little. The cells of this group always maintain the lead in the course of develop- ment. It is not only that they begin to develop and assume processes at an earlier period than the cells of the other groups, but the greater portion if not all of them appear almost simultaneously, and maintain an equal rate of growth during development. The antero-lateral differs in this respect from the postero-lateral and central groups, which increase in size by the gradual addition of new ganglion cells at their margins. It may be expected, therefore, that this group will regulate the fundamental actions, or the actions which are carried on in a reflex manner, and which are in great measure independent of the cephalic ganglia. In this con- nection the intercostal muscles, the diaphragm, abdominal muscles, and the muscles constituting the floor of the pelvis will immediately suggest themselves. In the lower extremity the most general movements may be expected to be regulated by the antero-lateral group. These move- ments are flexion of the thigh on the body, of the leg on the thigh, and elevation of the heel. It may be said that elevation of the heel is a movement almost peculiar to man, but this is rendered necessary during locomotion, owing to the depression of the heel which has been efi'ected in the course of evolution, by the progressive increase in the strength of the flexors of the foot on the leg. On watching the first movements of the human infant ifc will be seen that the power to elevate the heel is acquired early, while the elevation of the toe so as to allow the foot to swing forwards by its own weight is the last movement acquired ; hence it is the most special movement, and it will be represented in the cord by the superaddition of new ganglion cells to those already existing. What the movements are which are regulated by means of the antero-lateral group in the cervical region I can only make a rough conjecture. They are no doubt the simplest movements, and those which man possesses in common with the lower animals. The most probable of ^ these movements are flexion at the wrist, simple flexion and extension at the elbow, and the backwards and forwards movements at the shoulder, and flexion of the neck and head. Some of the muscles engaged in these actions we have already found reason to believe were innervated by the postero-lateral group ; but this does not exclude the possibility of their being innervated also by the antero-lateral group. There is so much uncertainty, however, with regard to the function of the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 75 autero-lateral group in the cervical region that it would be hazardous to make any assertion with regard to it. There is also quite as much uncertainty with respect to the functions of the central, internal, and anterior groups. § 375. Reflex Action. — The production of reflex action is one of the earliest and most fundamental functions of the spinal cord. As we have already seen, every reflex act requires for its performance an afferent and an efferent fibre, and a centre- The earlier-formed ganglion cells of the anterior grey horns con- stitute the centres of reflex action; and it is probable that the reflex afferent fibres pass to them directly, without the inter- vention of the grey substance of the posterior horns. Inasmuch as the reflex afferent fibres are formed at an early period in the development of the cord, they must be thrust out laterally during the development of the posterior grey horn, so that they will occupy an external position in the fan formed by the spreading out of the fibres of the posterior roots. We have already seen that there are grounds for believing that the afferent fibres of the tendinous reflexes pass in the inner radi- cular fasciculus, and it is not improbable that the afferent fibres of the cutaneous reflexes pass in the outer radicular fasciculus. The efferent reflex fibres pass out in the anterior roots, and the same fibres probably convey both reflex and voluntary impulses. § 376. Trophic Function of the Cord. — It is well known that the ganglion cells of the anterior horns of the cord exercise a trophic influence on the muscles ; but whether there are trophic cells endowed with special functions, or whether all the cells are endowed with both motor and tropl^ic functions, I am unable to say. With some degree of qualification, I feel inclined to adopt the latter view. It is well known that within certain limits, increased func- tional activity of a muscle is followed by an increase in its bulk, and, conversely, that a diminution of its activity is followed by diminution of its bulk. When, therefore, the mechanism in the cord, which regulates the movements of the muscle, is in a state of activity, this is followed by an increase in the function of the muscle, and consequently by an increase in its bulk. If, in 76 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. addition to an increase in its bulk, the muscle be called upon to make a new adjustment in response to altered circumstances, the new adjustment can only become permanent in the race when it is organised in the cord by the growth of new cells and fibres in addition to the original mechanism by which its move- ments were guided. But if the new cells and fibres become incapacitated from any cause, the muscle will soon lose the structural modification which corresponded to its recently- acquired functional adjustment, but no other change will take place in it. As long as the original mechanism is maintained in the cord, so long will the nutrition of the great bulk of the muscle go on as before. But tbe case is very different when the function of the original mechanism is destroyed ; then the nutrition of the muscle is injured at its very foundation, and profound trophic changes occur. It is very probable, therefore, that the inflaence exerted by the later-developed ganglion cells of the anterior horns on the nutrition of the muscles is small, while that of the earlier-developed cells is very great. § 377. Automatic Action. — The spinal cord contains a con- siderable number of what are regarded as automatic centres, but it is probable that many of these act in a reflex manner. The lumbar portion of the cord contains centres for the regulation of the acts connected with micturition, defecation, erection and ejaculation, and parturition. The oculo-pupillary centres in the upper dorsal and cervical regions of the cord have already been described. Vaso-motor centres exist in the cord by means of which the tonus of tbe muscular coat of the vessels is maintained. It has been thought that the spinal cord also exercises a tonic action over the skeletal muscles, but this opinion is doubtful. The tone of the sphincters of the bladder and rectum, however, is undoubtedly maintained by the lumbar part of the cord, and is probably reflex in character. The peristaltic movements of the oesophagus, stomach, and intestines are regulated by the central grey tube. Little is known beyond conjecture of the localisation of the centres of visceral innervation in the cord. That they are not situated in the anterior grey horns is ren- dered certain by the fact that the visceral movements, and ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 77 the automatic actions of defecation, micturition, erection, and parturition remain unaffected in disease limited to the anterior grey horns. Several considerations may be adduced tending to show that the vesicular column of Clarke contains the spinal centres of visceral innervation. The cells of this column are bipolar, like those of the sympathetic, and not multipolar, like those of the anterior horns which regulate the complicated actions of the skeletal muscles. This column is absent in the lumbar and cervical enlargements, the portions of the cord which supply nerves to the limbs, and in the upper half of the cervical region which supplies nerves to the muscles of the neck. It is, on the other hand, present in the upper lumbar and the dorsal regions of the cord — the portions from which the trunk is innervated, and is again represented in the medulla oblongata as the principal nucleus of origin of the vagus — the most im- portant visceral nerve of the body. It may be assumed that all the actions regulated through the vesicular colunin of Clarke are subordinated to the highest expanded portion of it which constitutes the nucleus of the vagus; hence there is no reason to assume that the medulla oblongata contains a circumscribed vaso-motor centre distinctly separated from the nucleus of the vagus, § 378. Functions of the Posterior Grey Horns and Posterior Roots. Afferent impulses are conducted to the spinal cord by the posterior roots. As already remarked, it is probable that the afferent impulses, which have undergone the highest organi- sation in the cord, are conducted by the fibres which occupy the periphery of the fan, formed by the spreading out of the fibres of the posterior roots as they enter the substance of the cord. In the anterior horns the most specialised actions are repre- sented, partly by the development of new processes to the existing ganglion cells, and partly by the growth of additional cells ; but in the posterior horns the fibres, which conduct the most specialised impulses, have become adapted to their functions by the gradual development in connection with them of special peripheral terminal organs on the one hand, and 78 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. central terminal organs on the other. The stimulation of certain fibres in an early stage of development may give rise only to diffused and irregular contractions, while at a higher stage of development complicated and apparently purposive reflex movements are produced by a similar stimulation; again, a stimulation which at an early stage of development gives rise only to a diffused sensation of pain, may at a higher stage of development evoke intellectual sensations of touch and tem- perature. It may, therefore, be expected that the fibres which conduct reflex impulses, and those that conduct the impulses which on reaching the cortex of the brain give rise to the intellectual sensations, will occupy the periphery of the fan of the posterior roots; while those which conduct the impulses which on reaching the cortex give origin to the common or emotional sensations will occupy its centre. We have already seen reason for believing that the afferent fibres of the tendinous reflexes pass through the internal radicular fasciculus to reach the posterior horn, and it is probable that the afferent fibres of the sense of touch and locality also pass through the same fasci- culus. We have also supposed that the cutaneous reflex fibres pass through the external radicular fasciculus, and it is probable that the afferent fibres of the sense of temperature likewise pass through this bundle. The afferent fibres of the common sensa- tion of pain pass through the centre of the posterior roots directly into the grey matter of the posterior horns. Section of the white posterior column destroys the sensation of touch permanently in the regions situated below the section, but leaves the sensation of pain unaff"ected ; and, con- versely, section of the entire grey substance, leaving the posterior columns intact, destroys the sense of pain and leaves that of touch (Schifif). A retardation of the conduction of sensation occurs when the posterior grey horns are cut, and the more the grey substance is diminished the more marked is the retardation. The conduction of sensory impressions decussates in the cord soon after the root fibres enter it, but considerable difference of opinion exists as to the mode and extent of this decussation with regard to the con- ducting paths of the diflerent kinds of sensation. The further course of the afferent fibres through the cord is not well known. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 79 It is supposed that the sensory paths of the lower extremities lie at first in the lateral columns, and do not enter the posterior columns till they reach a higher level. The posterior column of the lumbar region is said to contain only the nerves of touch for the pelvic region, sexual organs, perinseum, and anal region (Erb). § 379. Fwndions of the Central Orey Column. — The central grey column is not supposed to be endowed with any active func- tions, yet, pathologically regarded, it is, as will hereafter appear, one of the most important portions of the grey sub- stance of the spinal cord. The continuation of this column in the medulla oblongata contains, as we have seen, the accessory nuclei ; and the median areas of the anterior horn in the cervical and lumbar enlargements, as well as the medio-lateral areas in the dorsal and upper cervical regions, may be regarded respectively as anterior and lateral outgrowths of the central column, instead of being regarded as portions of the anterior horns. These areas, indeed, constitute the border-land between the central column and anterior horn, and they are involved in the diseases of both structures. § 380. Functions of the Special Nuclei of the Medulla Oblongata, Pons, and Crura. — The functions of the special nuclei do not require extended consideration at present. All of them serve to transmit impulses received through the nerves of special sense, not only to the cortex of the brain, but probably also to the cortex of the cerebellum, while likewise ministering to complex reflex actions. The corpora quadrigemina, for instance, are anatomically connected, not only with the cerebrum, but also with the superior peduncles of the cerebellum ; while they have been proved, both anatomically and experimentally, to form an important reflex centre between the retina and the internal and external muscles of the eye. It is, indeed, likely that still more extensive and complex reflex actions are regu- lated by the corpora quadrigemina, since they are known to be anatomically connected with the upward continuation of the anterior root -zones of the spinal cord. Two of the four nuclei of origin of the auditory nerve are intimately connected with 80 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. the inferior and middle peduncles of the cerebellum, and it is probable that one of them at least conducts labyrinthine im- pressions to the cerebellum. The corpora quadrigemina are homologous with the optic lobes in fishes and the lower vertebrata — organs which are developed in connection with the sense of sight. These ganglia appear to be the centres for the reflex co-ordination of all the muscular actions concerned in the movements of the eyeballs and of the refles contraction of the pupils caused by light falling on the retinse. It is through these bodies, and not directly, that the optic tracts come into relation with the cerebellum ; hence it may be expected that they will be associated with the latter in its functions. We have already seen that the corpora quadrigemina are connected with the anterior root-zones, or the system of fibres which co-ordinate the actions of the cord longitudinally on the side of the outgoing currents ; hence the inferior segments of the body are to a considerable extent brought under the regulative influence of these ganglia. The corpora quadrigemina are, however, simple co-ordinating centres, and their regulative action on the inferior segments of the body is of a purely reflex character. The following may be taken as an illustration of the manner in which I believe them to act : — While a fish is swimming through the water a sudden impression is made on the right eye by the shadow of a large approaching object, and immediately the muscles of the tail on the left side contract, and the head is turned away from the object. Such a movement would tend to secure the safety of the fish from capture by a more powerful antagonist. If, on the other hand, the impression is made by a relatively small object, the muscles of the tail on the same side might contract, so as to turn the head towards the object — a movement which would tend to secure prey. In these movements the main regulative centres are the optic lobes, and there is no occasion to believe that the actions are in any way of a difierent character from the ordinary reflex movements of the spinal cord. It may, however, be remarked, in passing, that since a large approaching object would produce a greater impression than a small object, a rudimentary eye would be more useful to its possessor for avoiding capture than in securing prey ; and, consequently, the primary and fundamental connection between the eye and the inferior segments of the body would be a crossed one. The most ready communication, therefore, would be between the right eye and the muscles of the left side of the body. And this helps to explain the crossing of the optic nerves, not only in the lower animals with rudimentary eyes, but in the higher organisms ; since, during the develop- ment of the latter from the former, the primary and fundamental crossing, however much it may be modified, is still retained. It is, indeed, very probable that the crossed connection which may be supposed to exist in the lower vertebrata between the rudimentary eyes and the muscles of the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 81 body was the main factor in determining during the course of development the crossed connection which exists between the cerebral hemispheres and the spinal cord in the higher vertebrata. § 881. Functions of the Superadded Grey Substance of the Medulla Oblongata, Pons, and Crura. — We have already seen that there are no grounds for believing that the centres of respiration, deglutition, mastication, and the regulation of the heart's action, the vaso-motor diabetic, and so-called con- vulsive centre of Nothnagel, are represented by grey matter in the medulla, apart from that which is the up'ward con- tinuation of the grey substance of the spinal cord, and conse- quently the masses of grey matter which are superadded in the medulla, pons, and crura, must preside over other important functions. Little, however, is known with respect to these. The most reasonable supposition I can form is that all of them are coDnected with the cerebello-spinal system, and are, therefore, engaged in regulating the tonic muscular contractions rendered necessary to maintain the various attitudes of the body. § 382. Functions of the White Substance. — According to the fundamental law of development already mentioned, we may expect that the parts of the cord which begin to develop at an early period are engaged in the most general actions ; while those which develop at a late period are engaged in the most special actions. The most general actions of the cord are those which it performs as a group of simple co-ordinating centres; and the most special are those which it performs in subordina- tion to the compound and doubly compound co-ordinating centres. We may, therefore, expect to find that the anterior and posterior root-zones, which appear at a comparatively early period in the development of the cord, belong to the spinal system of simple co-ordinating centres, while the direct cere- bellar fibres, the column of Goll, and the pyramidal tract, which appear at a comparatively late period of development, bring the simple co-ordinating centres of the cord under the control and guidance of the compound and doubly compound co-ordinating encephalic centres. So far as can be ascertained, this expectation is realised. G 82 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. § 383. Functions of the Anterior and Posterior Root-zones. These consist, as already stated, of looped fibres, which connect ganglion cells at different elevations in the cord. The anterior root-zone maintains a close relationship with the anterior grey horns, and its fibres probably assist in co-ordinating efferent impulses from above downwards. But although the anterior root- zone belongs primarily to the spinal system, it is not im- probable that it may have become at a subsequent stage of development connected indirectly, if not directly, with some of the cephalic centres. The close relationship of the olivary body with the anterior root-zone in the medulla would seem to imply that the latter may be the medium of conveying efferent impulses from the cerebellum. The anterior root-zone is also probably connected with the corpus striatum, and may therefore be the channel through which the efferent impulses from the latter are conveyed downwards to the cord. It is also connected with the corpora quadrigemina, and may serve to convey reflex impulses originating in the retina down the cord. The posterior root-zone, on the other hand, maintains an equally close relationship with the posterior grey horns, and its fibres probably assist in co-ordinating afferent impulses from below upwards. We have seen that, with the exception of the part which belongs to the sensory roots of the fifth nerve and the fasciculus rotundus, the posterior root-zone terminates in the triangular nucleus, and that the latter is connected by arcuate fibres with the olivary body, which in its turn is connected with the opposite half of the cerebellum. This indirect con- nection with the cerebellum would appear to indicate that some at least of the fibres of the anterior root-zone belong to the cerebello-spinal system. § 384, Functions of the Direct Cerebellar Tract. — This tract belongs to the cerebello-spinal system, its fibres connecting the vesicular column of Clarke and the cortex of the cerebellum (Flechsig), Little is known with regard to the functions of these fibres, except that they appear to convey afferent im- pulses. This is presumed to be the case, because when the fibres of the tract are injured in any part of their course, the portions above the seat of injury undergo rapid degeneration. ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. 83 § 385. Functions of the Column of Ooll. — This column must be regarded as a special structure from the comparatively late period at which it is developed. Its fibres also undergo rapid degeneration above the seat of injury; hence it may be inferred that they convey afferent impulses, but nothing further is known with regard to their functions. § 386. Functions of the Pyramidal Tract — This tract is now well known to be the means of communication between the motor area of the brain and the anterior grey horns of the cord. The fibres which pass into the lateral column connect the anterior grey horn of one side with the cortex of the opposite side ; while those which constitute the column of Tiirck connect the anterior horns and cortex on the same side. When the fibres of the tract are injured in any part of their course the portions below the seat of injury undergo rapid degeneration, and this fact alone is sufficient to indicate that these fibres convey efferent impulses. This tract is, indeed, the channel by means of which voluntary impulses are conveyed from the cortex of the brain to the spinal cord. The crossed and direct connec- tion which this tract forms between the cortex of the brain and the grey anterior horns, is rendered necessary by the fact that every movement of one side of the body alters the centre of gravity, and necessitates a new adjustment of the opposite side. I obtained this idea in a conversation with Dr. Hughlings Jackson, and he illustrated his meaning by showing that when a man stands on the ball of the right foot, and stretches his right arm upwards and forwards to reach an object, the body being also inclined forwards, the left leg is instinctively thrust backwards, and the left arm downwards and backwards, in order to keep the centre of gravity as far back as possible and so to prevent the line of gravity from passing in front of the ball of the right foot. The muscular contractions of the right side of the body may be supposed to be regulated in this action from the left cortex of the brain through the fibres of the pyramidal tract of the lateral column of the right side, while the movements of the left arm and leg are also regulated from the left cortex, but the impulses are conveyed to the same side of the cord and of the body by the fibres of the column of Tiirck. 84 CHAPTER II. MORBID ANATOMY AND CLASSIFICATION OF THE DISEASES OF THE SPINAL CORD AND MEDULLA OBLONGATA. . (I.)— MORBID ANATOMY OF THE SPINAL COED AND MEDULLA OBLONGATA. In the preceding chapter we have traced the operation of the law of evolution in the development of the spinal cord and medulla oblongata ; we must now trace the operation of the law of dissolution in the breaking down of the structure of these organs by disease. § 387. Histological Changes. — The histological changes which occur in the various elements of the structure of the cord must first be briefly described. 1. Morbid Changes of the Ganglion Cells. (a) Hypertrophy. — In acute inflammation of the cord the ganglion cells become swollen, their contents clondy and granular, the processes also taking part in the changes {Fig. 144, 2). These cells often -contain a large amount of yellow pigment, a condition which has been described by Dr. AUbutt as " yellow degeneration " {Ficj. 144, 3). (6) Shrinking. — In the acute diseases of the grey substance of the cord, the ganglion cells, especially the small cells of the median areas, become shrivelled, their fluid contents appear to have escaped, and the cell wall to have shrunk around the nucleus and a small quantity of yellow pigment {Fig. 144, 4). At a subsequent period the cells lose their processes and become converted into small angular masses, in which even a nucleus cannot be detected. (c) Multiplication of the Nucleus and Nucleolus. — The nucleus and nucleolus may at times be observed either to have divided into two, or to exhibit an hour-glass contraction indicating that the process of division has commenced. (d) Vacuolation. — Two or three large spherical air spaces, named MORBID ANATOMY OF THE SPINAL CORD. 85 vacuoles, may sometimes be observed in ganglion cells which have under- gone a granular degeneration {Fig. 144, 7). (e) Colloid Degeneratio7i. — The hypertrophied cells of the early stage of inflammation may subsequently undergo colloid degeneration. Their processes become transparent, glistening, brittle, and a large number of them are broken off so that the cells assume a rounded form. The cell wall has a glassy appearance, and assumes brilliant tints when stained by various aniline dyes. The colloid appearances may probably be the result of post-mortem changes, and consequently considerable caution must be exercised in accepting them as evidences of disease. {f) Pigmentary Degeneration. — The best examples of pigmentary de- generation are seen in the chronic diseases of the cord. The cell wall Fig. ]44. Fig. 144 (Young). Ganglion Cells of the Anterior Grey Horns of the Spinal Cord. - 1, Healthy caudate cell; 2, Hypertrophied cell; 3, Yellow degeneration (the yellow colour cannot be represented here) ; 4, Shrivelled cell ; 5, Chronic atrophy, a group of cells from a case of pseudo-hypertrophic paralysis ; 6, Pig- mentary atrophy ; 7, Vacuolation, from a case of canine chorea (Gowers) ; 8, Chronic atrophy, from a case of progressive muscular atrophy- -" yellow atrophy." 86 MORBID ANATOMY OF THE becomes contracted around a mass of dark granular pigment, the nucleus and nucleolus are indistinct or obliterated, the processes are atrophied, and many of them have disappeared {Fig. 144, 6). {g) Atrophy. — In chronic diseases the cell wall becomes dense and contracted, the processes broken ofif, and the remnant of the cell converted into a small angular mass, without recognisable nucleus or nucleolus, and finally all traces of the cell may be lost {Fig. 144, 5 and 8). (Ji) Calcareous degeneration of the ganglion cells of the cord is rarely observed (Forster). 2, Morbid Changes of the Nerve Fibres. The meduUated nerve fibres of the spinal cord undergo alterations more or less similar to those which have already been described in the case of the fibres of the peripheral nerves, and consequently these changes need not be described here in detail. {a) Hypertrophy of the Axis Cylinder, — In myelitis it is not rare to observe on transverse section that the axis cylinders of many of the fibres have increased to two or three times their normal dimension. In longitu- dinal sections it is seen that the swelling does not extend the whole length of the axis cylinder ; the latter presents a varicose appearance, so that its diameter is much diminished in size at some points. (6) Atrophy of the nerve fibres, similar to that which occurs in the peri- pheral nerves when the fibres are severed from their trophic centres, may be observed in the meduUated fibres of the spinal cord. This atrophy begins by coagulation of the myeline, which becomes granular and broken up into globular masses that are finally absorbed. The axis cylinder per- sists for a long time after the medullary sheath has disappeared, but by- and-by it also diminishes in size, and ultimately disappears. (c) Calcareous degeneration of the fibres of the cord has been excep- tionally observed (Forster, Virchow). 3. Morbid Changes of the Neuroglia and Connective Tissue. (a) Gliige's corpuscles consist of large globular cells filled with granular contents. These cells may be observed in the spinal cord of the embryo, but are never met with in considerable numbers in the cord of the adult, except in cases of disease. They are supposed to derive their origin from fatty degeneration of the cells of the connective tissue and neuroglia, the white corpuscles of the blood, and the endothelial cells of the vessels and of the capsules of the ganglion cells. (6) Amyloid Corpuscles and Colloid Bodies. — Amyloid corpuscles (cor- pora amylacea) are small, round, concentrically laminated bodies. Most of them are turned blue, or bluish grey, when acted on by iodine alone, and assume a beautiful bright blue tint on the addition of sulphuric acid. Colloid bodies are irregular masses, consisting apparently of changed myeline ; they assume beautiful tints on being stained with logwood, or some of the aniline dyes. It is probable that these bodies may be the SPINAL CORD AND MEDULLA OBLONGATA. 87 result of post-mortem decomposition, and neither they nor the amyloid corpuscles afford trustworthy evidences of disease. (c) Deiter's cells appear to be increased in number in inflammatory diseases of the cord. (d) Hypertrophy and Hyperplasia of the Connective Tissue. — The septa of connective tissue become swollen, and the nuclei of the neuroglia largely increased in number. It is also probable that leucocytes, which have migrated from the vessels during inflammatory processes, may sub- sequently become organised, and thus increase the normal volume of the connective tissue of the cord. (c) Sclerosis and Retraction. — When hyperplasia of the connective tissues has once taken place, the newly-formed tissue may subsequently undergo cicatricial contraction, and thus lead to the destruction of the nervous elements. The process which leads to sclerosis often begins in the nerve cells and fibres, and may be called parenchymatous sclerosis. At other times the morbid changes appear to begin in the connective tissue or neuroglia, the nerve cells and fibres being secondarily invaded ; this form may be called interstitial sclerosis. 4. Morbid Alterations of the Vessels. (a) Intravascular Changes. — The vessels are at times greatly distended with blood, but this is not a trustworthy evidence of disease, inasmuch as the distension may have occurred from the mode of dying, or from hypo- static congestion after death. The capillary arteries may at times be distended with emboli. (b) Changes in the walls of the spinal vessels are observed in chronic Bright's disease, identical with those which occur in the vessels of the body generally in that disease. (c) Perivascular Changes. — The most important perivascular changes observed in disease of the spinal cord are caused by migration of the white corpuscles of the blood into the perivascular lymph-spaces and surround- ing tissues. The number of leucocytes surrounding a vessel may some- times be so great as to constitute what has been called a miliary abscess (Plate v., Fig. 2). Rupture of a vessel may occur, giving rise to haemorrhage into the tissues. Red blood corpuscles are at times localised in a perivascular space, but it is difiicult to determine in these cases whether the red corpuscles have escaped by rupture, or have, like the white corpuscles, migrated through the wall of the vessel. § 388. Let us now pass from the details of the morbid changes of the cord to the general principles which underlie them. In accordance with the law of dissolution (§ 35) we may expect that the accessory portions of the cord will form parts of least resistance to the inroads of disease. In the grey substance the least resistance to disease will be 88 MORBID ANATOMY OF THE offered by the central column, which is, as we have already seen, the embryonic area of the cord, and by the median area of the anterior grey horn in the lumbar and cervical enlarge- ments and the medio-lateral area in the dorsal and upper cervical regions — areas which, as already remarked, may be regarded as outgrowths of the central column. These areas contain the accessory nuclei of the spinal cord, and since these ganglion cells not only are developed at a comparatively late period, but also frequently maintain a relatively small size in the adult, the resistance offered to the invasion of disease becomes still less. This law must necessarily be true whether the disease begin in the ganglion cells themselves, in the neuroglia, or in the vessels, or whether it be caused by a poison circulating in the blood, provided that the poison possess no special affinity for any one set of the ganglion cells more than for others. The cell walls of the small and recently-developed cells are much thinner than those of the larger and earlier-developed cells, hence the exchange of materials, which is the necessary accompaniment of nutrition, takes place more readily in the former than in the latter. But this is not all. A large cell presents, in proportion to its bulk, a smaller surface to its environment for the absorption of nourishment than a small cell, and consequently the relative amount of nourishment absorbed by the large will be less than that absorbed by the small cell (§ 9). But high nutritive activity is associated with great instability, which declares itself in increased readiness to give out energy or to multiply, the latter process, of course, involving the disorganisation of a highly-organised tissue. When, therefore, the ganglion cells of the anterior horns become diseased, it may be expected that the later-developed and small cells will be the first to suffer, and when a poison like strychnine circulates in the blood, the same cells will also be the first to be affected, supposing the drug not to possess a special affinity for one ganglion cell more than for another. The reason of this is, that the quantity of the poison which will enter the substance of the small cell will be much larger in proportion to its bulk than that which will enter into the substance of the large cell. If the disease begin in the neu- SPINAL CORD AND MEDULLA OBLONGATA. 89' Fig. 145. roglia, it may be expected that the spongy and loose neuroglia of the later-developed portions of the grey substance will resist its inroads less effectually than the dense neuroglia surrounding the earlier-developed groups of ganglion cells. The central grey column possesses a loose and spongy neuroglia, and we have seen that it may be regarded as the embryonic area of the spinal cord, so that it may be expected to offer little resistance to the invasion of disease. We shall hereafter see that some of the most rapidly fatal diseases of the cord appear to ascend in the central grey column. It has been pointed out that the later-formed cells of the anterior horns grow close to the arteries, while the earlier-developed cells are pushed, in the course of development, away from them. When, therefore, rapid exudation takes place from the vessels, whether it consist of a fluid and granular exudation or of migration of white blood corpuscles, the cells in the neigh- bourhood of these vessels Avill suffer sooner and in greater de- gree than those more remote. That the lines of least resis- tance to disease in the lumbar region are in the direction of the vessels is well illustrated by Fig. 145, which is taken from a section of the middle^ of the lumbar en- largement in a case of infantile paralysis, under the care of Dr. Humphreys, at the Pendlebury Hospital for Sick Children. This case is described in the " Transac- tions of the Pathological Society of London" for 1879, and will be subsequently mentioned. My present object is to show that even in an acute disease like infantile paralysis the cells near the vessels have become de- stroyed in preference to the Fig. 145 (Young). Section of the Lum- bar Region of the Spinal Cord from a case of infantile spinal 2^araly sis. pi, postero- lateral group; al, antero-lateral group ; c, central group. The internal and anterior groups have disappeared, and the marginal cells of the remaining groups are also destroyed. 90 MORBID ANATOMY OF THE others. If Fig. 145 be compared with Fig. Ill, it will be seen at once that the disease is most marked in the vascular areas of the cord, and that the cells which have been last developed are, on the whole, those which have suffered most will be apparent by referring to the previous description and illustrations of the development of the cord. It is true that the earlier-developed cells of the internal and anterior groups have disappeared ; but the cells of the antero-lateral, and those of the central portions of the postero-lateral and of the central group are well preserved ; while the marginal cells of the two latter groups and all the cells of the median area are completely destroyed. It is not likely that this law will always be observed in a disease having such an acute and sudden onset as infantile paralysis ; but an examination of the diagrams given by Clarke, Charcot, and Jofifroy, shows so many indications of the fulfilment of this law that its occurrence cannot be regarded as accidental. The same law is observed, at least very frequently, in cases of acute and subacute ascend- ing central myelitis, as well as in tetanus and hydrophobia. It was while examining cases of this kind that my attention was first directed to this subject. In all the acute diseases affecting the grey substance of the spinal cord I observed that, unless the destruction was so great as to involve the anterior horns in their entire extent, the small cells and those in the line of the distribution of the arteries manifested evidences of disease to a much greater extent than the large cells and those removed from the vessels. The distribution of the disease in the cervical enlargement is similar to that in the lumbar region, except that the median area being much larger in the former than in the latter, injury to this area forms a more conspicuous feature of disease in the former than the latter. When the dorsal region of the cord is affected by acute disease of the grey substance, the most marked morbid changes are observed in the postero-lateral or rather the medio-lateral group; and the same is the case in the upper cervical region. A section of the middle of the cer- vical enlargement is represented in Fig. 146, taken from a case of subacute ascending spinal paralysis. The disease began after exposure to severe cold with sudden paralysis of the lower SPINAL CORD AND MEDULLA OBLONGATA. 91 extremities, without much disturbance of sensibility. This was followed by rapid wasting of the muscles, and loss of faradic contractility. The paralysis in the course of a few weeks gradually invaded the muscles of the trunk, the muscles of the upper extremity, and ultimately the muscles of respiration. Death took place five weeks from the commencement of the paralysis. In the lumbar region the white as well as the grey substance was implicated, and there was ascending sclerosis of both the columns of Goll and of the direct cerebellar tracts throughout the entire length of the cord ; the remaining por- tions of the white substance were healthy in the dorsal and cervical regions. The central grey column was diseased throughout the whole length of the cord, the cells of the postero-lateral group and medio -lateral area having entirely disappeared in the dorsal region, and again in the upper cervical regions; while the anterior groups of cells appeared Fig. 146. Fig. 146 (Young). Section of the Middle of the Cervical Enlargement of the Spinal Cord from a case of central myelitis. — i. The internal group ; the remaining letters indicate the same as the corresponding ones in Fig. 145. The median area was completely destitute of cells, and a large number of the marginal cells of the different groups of the anterior horn were destroyed or diseased. 92 MORBID ANATOMY OF THE to be quite normal. In the cervical enlargement {Fig, 146) the cells of the median area had entirely disappeared, and the marginal cells of the central and postero-lateral groups were notably altered, while the fundamental cells of the groups presented beautiful long processes, and appeared in every respect normal. § 389. In the white substance the last developed fibres will also, other things being equal, offer less resistance to the inroads of disease than the earlier-developed fibres. In proceeding to verify this statement, we must compare the later with the earlier- formed fibres of the same segment, or, in other words, the same functional system of the white substance, otherwise the whole result will be vitiated. The posterior and anterior root-zones, for instance, are developed about the same time, yet the former is more liable to become diseased than the latter. The posterior is probably more exposed to the exciting causes of disease, such as peripheral injuries and ascending neuritis, than the anterior root-zone, and the small fibres of the former are more apt to be injured in inflammatory affections of the cord than the larger fibres of the latter. But if the accessory be compared with the fundamental fibres of the pyramidal tract, it will be seen that the former are much more exposed to injurious influences than the latter. The small diameter of the greater number of the accessory fibres permits a relatively larger amount of nourishment to gain access to their interior than can take place in fibres of larger diameter ; hence both reparative and destructive changes are more rapidly effected in the former than in the latter. The accessory fibres are, as we have seen, more closely related to the connective tissue septa of the cord than the fundamental fibres, hence the former are more liable to be injured in the course of the diseases which begin in the connective tissue and neuroglia than the latter. An appearance which is presented by the spinal cord in various diseases, and which for a long time puzzled me very much, is that which has been described as miliary sclerosis (Rutherford, Kesteven). This condition appears to consist of a swelling or thickening of the septa in which the blood-vessels run. In the lozenge-shaped spaces {Fig. 133) of SPINAL CORD AND MEDULLA OBLONGATA. 93 the pyramidal tract a considerable number of the small fibres which lie close to the vessels are destroyed, while the larger central fibres remain more or less healthy. When a transverse section of the cord is examined under these circum- stances the part presents a spotted appearance, but instead of the miliary spots being in a state of sclerosis, they really are the most healthy portions of the section. The proximity of the fibres of the accessory system to the blood-vessels renders them also more liable than the fundamental fibres to be injured by inflammatory and other effusions. § 390. Secondary Degenerations. The medullated fibres of the spinal cord undergo degene- ration whenever their continuity is interrupted. The short looped fibres of the anterior and posterior root-zones, however, only degenerate in the neighbourhood of the lesion, probably because they soon terminate in grey matter. But the fibres which pass from one end of the cord to another are sometimes found degenerated throughout their whole length. As a rule, however, a focal lesion interrupts the continuity of the long fibres in some part of their course, and the fibres either above or below the seat of disease undergo degeneration. Some pathologists think that an irritative change spreads from th6 primary lesion as a centre along these fibres, but the most reasonable supposition is that the degeneration is analogous to what occurs in the fibres of peripheral nerves after they have been severed from their trophic centres. The trophic centres of the fibres of the columns of Goll and of the direct cere- bellar tract are situated at their inferior extremities — the posterior horn containing the trophic centres of the former, and the vesicular column of Clarke possibly that of the latter. When, therefore, the continuity of these fibres is inter- rupted at any point, the portions above the seat of the lesion undergo degeneration, consequently degeneration of these fibres is called ascending sclerosis. But the trophic centres of the fibres of the pyramidal tract are situated at their superior extremities, these centres being probably formed by the large ganglion cells of the fourth layer of the cortex of the brain. When the continuity of these fibres is interrupted at any 9i MOEBID ANATOMY OF THE point of their course, the portions below the seat of the lesion undergo degeneration, consequently this form is called descend- ing sclerosis. The time occupied by the degeneration appears to be from four to eight weeks. Schiefferdecker found in experiments on dogs that it began at the end of fourteen days, was well marked at the end of four to five weeks, but changes in the connective tissue were not observed until the eighth week. Degeneration of the fibres of the spinal cord appears always to take place in the line of their conduction. When a transverse section of the spinal cord is examined by the naked eye the degenerated portion usually presents a grey or greyish discolouration, but in recent cases the cord presents no abnormal appearances until it is hardened in chromic acid or bichromate of ammonia. In cases of long standing the degenerated columns may be atrophied to such an extent that the sym- metry of the cord becomes altered. Microscopic examination shows that in the earlier stages the nerve fibres are exclusively affected. The medullary sheaths undergo fatty degeneration and ultimately disappear, while there is a considerable development of granule cells ; the axis- cylinders, however, persist for some time afterwards. In the later stages of degeneration the nerve fibres disappear entirely, the neuroglia is increased in quantity, and changes into a dense finely fibrillated tissue, which contains numerous nuclei and spindle cells. 1. History. — Secondary atrophy, extending to the pons and pyramids of the medulla, was observed in disease of the brain by Cruveilhier and Rokitansky, but they did not follow it to the spinal cord. Tiirck made a thorough examination of the secondary degenerations of the spinal cord in 1851 and 1853, and their histological characters were investigated in 1863 by Leyden. Various French authors, as Charcot, Cornil, and others, published cases in which these degenerations were observed, but the most exhaustive work on the pathology of the affection was published by Bouchard in 1866. Soon afterwards Westphal showed that secondary degenerations could be produced experimentally in dogs, and this was afterwards confirmed by Vulpian. 2. Distribution of the Degeneration. — The observations of Charcot and Pierret, and subsequently of Flechsig, tend to show that these secondary degenerations of the spinal cord are determined by the order of its deve- lopment. The development of the functional systems of the white sub- SPINAL COED AND MEDULLA OBLONGATA. 95 stance of the cord affords a good illustration of the law of evolution, while the secondary degenerations afford an almost equally good illustra- tion of the law of dissolution. The distribution of these degenerations, therefore, may be readily understood by reference to Figs, 134 to 140, which illustrate the development of the cord. (a) Ascending degeneration takes place above the seat of the lesion in the columns of Goll, and terminates in the upper end of the medulla oblongata, where the fibres end in the cuneate nucleus. The direct cerebellar fibres also undergo ascending degeneration. It may begin as a thin lamella of degenerated tissue on the external surface of the lateral column in the lower dorsal region, the area of the degeneration gradually increasing in size upwards along the cord and the external surface of the restiform bodies. In lesions of the cauda equina, and sometimes after severe traumatic injui'ies of the sciatic nerve, the posterior root-zones, as well as the columns of Goll, undergo ascending degeneration in the lumbar and greater portion of the dorsal regions, but the degeneration becomes limited to the columns of Goll in the upper dorsal and cervical regions. Fig. 147. Fig. 148. Fig. 149. Figs. 147, 148, and 149. Transverse Sections of the Spinal Cord, from the middle of the cervical enlargement, middle of the dorsal region, and middle of the lumbar region respectively, showing ascending degeneration of the column of Goll (g), and of the direct cerebellar tract {dc). (6) Descending degeneration occurs in all destructive lesions of the brain or spinal cord which injure the fibres of the pyramidal tract in their passage through the corona radiata, internal capsule, crus cerebri, pons, Fig. 151. Fig. 152. Figs. 150, 151, and 152 (.Aiter Charcot). Transverse Sections of the Spinal cord, from the middle of the cercical enlargement, middle of the dorsal region, and middle of the lumbar region respectively, showing primary lateral sclerosis of the cord, or secondary to a lesion high up in the cord or medulla oblongata. —A, A, A, De- generated pyramidal tracts. 96 MORBID ANATOMY OF THE Fig. 153. medulla, or cord. In the diseases of the cord, the degeneration is generally bilateral and symmetrical, and the position occupied by the diseased por- tions of the cord in the lateral columns is represented in Figs. 150, 151, and 152 ; the degeneration of the columns of Tiirck is, however, not shown. The position occupied by the diseased portion in the medulla ob- longata is represented in the annexed woodcut {Fig. 153, A), In cerebral lesions the degenerative tract is gene- rally limited to one side— the side of the cord opposite the lesion in the brain — as represented in Figs. 154 to 156. The columns of Tiirck on the same side as the lesion of the brain are also usually simultaneously degenerated, but this is not represented in the figure. Fig. 153 (After Charcot). Transverse section of the medulla oblongata, on a level with the middle of the olivary body. — A, A, Sclerosis of the anterior pyramids. Fig. 155. Figs. 154, 155, and 156 (After Charcot). Transverse Sections of the Spinal Cord, from the middle of the cervical enlargement, middle of the dorsal ■^-egion, and middle of the lumbar region respectively, showing descending sclerosis of the pyramidal tract in the lateral column secondary to a cerebral lesion. — A, A, A, De- generated pyramidal tract. 3. Degeneration of the Spinal Cord Secondary to Amputation. — The changes which occur in the spinal cord after amputation have been studied by Berard, Cruveilhier, Tiirck, Dickinson, Lockhart Clarke, Vulpian, and others ; and, in a recent number of the Journal of Anatomy and Physio- logy, Dr. Dreschfeld has given a good resumd of the previous observations of others, while adding new observations of his own. The general result appears to be that the peripheric nerves and the white substance of the cord are unaffected, the posterior roots are often slightly diminished in size, and changes in the ganglion cells of the anterior horns are of constant occurrence. Some of the ganglion cells of the anterior horns have com- pletely disappeared, whilst those that remain are atrophied and shorn of their processes. Judging from the various drawings, the ganglion cells of the margins of the various groups disappear first, and those of their centres remain to the last. The cells of the postero-lateral group are particularly liable to be affected. No mention is made of the disappearance of any of the ganglion cells from the anterior horn on the side opposite to that of SPINAL CORD AND MEDULLA OBLONGATA. 97 the amputated limb ; but judging from the diagrams which illustrate Dr. Dreschfeld's paper, I should think that the number of cells in the internal group of the opposite side is much diminished. The fibres of the external fasciculus of the posterior root pass through the anterior commissure to join the cells of the internal group, and in future cases it would be worth while to observe whether a streak of degeneration might not be detected along the course of these fibres to reach the internal group of the opposite side. Hayem tore out the sciatic nerve of one side in rabbits, and found in the lumbar region of the cord on the same side sclerosis of the posterior root and posterior grey matter, along with degenerative atrophy of the ganglion cells of the intermedio-lateral tract. § 391. Deformities and Malformations of the Spinal Cord. The deformities and malformations of the spinal cord may be subdivided into — (1) the congenital deformities which are incompatible with the maintenance of extra-uterine life ; (2) the congenital deformities which are compatible with life, and do not betray themselves by any symptom during life ; (3) the congenital deformities which may be recognised during life ; (4) acquired deformities resulting from pathological processes (Syringomyelia, Hydromyelus acquisitus) (Leyden). The following are the more frequent conditions observed (Leyden) : — 1. Congenital Deformities of Still-born Children. (a) Amyelia, or absence of the spinal cord. It is only met with when the brain is also absent. (6) Atelomyelia, or imperfect development of the spinal cord. The upper end of the cord is lacking or imperfectly developed, the brain being also absent (anencephalia), or the head defective (acephalia). The me- dulla oblongata is absent or exists only in a rudimentary form. (c) Diastematomyelia is a condition in which the two lateral halves of the cord either do not unite, or unite only throughout a portion of their extent. This malformation occurs with anencephalia. {d) Diplomydia, or duplication of the spinal cord, appears in the various forms of double monsters. ^1. Congenital Deformities which cannot be recognised duriJig Life. (a) Anomalies in the Length and Thickness of the Cord. — The cord is found at times thick and voluminous, and at other times thin and small. It descends at times to the third lumbar vertebra, and ends at other times opposite the eleventh or twelfth dorsal. (6) Abnormal smallness of the entire spinal cord and medulla oblon- gata, with corresponding smallness of the nerve fibres and axis cylinders, H 98 MOEBID ANATOMY OF THE has recently been described by F. Schultze, in one of Friedreich's cases of " hereditary ataxy." (c) Asymmetry of the grey substance, showing unequal width and depth of the anterior grey horns on a transverse section. {d) Abnormalities of the Pyramidal Tracts. — Flechsig has recently shown that the fibres of the pyramidal tracts are very variable in their distribution. Each pyramid may send its mass of fibres into the spinal cord, either entirely crossed or only partly crossed, or down the anterior columns almost entirely uncrossed. These tracts are absent in anence- phalous monsters (Flechsig). In cases of congenital absence or intra-uterine arrest of development of certain extremities atrophy of definite portions of the spinal cord may be observed producing asymmetry, which is limited to the cervical or lumbar enlargement according to the extremity afiected. In a case of congenital talipes equino- varus of both legs, I found the conus medullaris remarkably thin and tapering. On transverse section the anterior grey horns were seen to be deformed, the internal border which in health runs parallel with the anterior fissure being drawn out- wards and backwards, so as to be almost in a line with the anterior border of Fig. 157. Fig. 157. Transverse Section of the upper end of the Conus Medullaris of the Spinal Cord, from a case of congenital talipes equino-varus.—A, P, Anterior and posterior horns respectively ; i, internal group showing healthy cells ; a, anterior, al, antero-laleral, pi, postero-lateral, and c, central groups of cells, each being represented only by a few small round cells without processes. SPINAL CORD AND MEDULLA OBLONGATA. 99 the anterior commissure. The ganglion cells of the internal group were well developed, although it was displaced from its usual position {Fig. 157, i). A few cells were observed in the posterolateral area; but the cells of the anterior, central, and antero-lateral groups were entirely absent in many sections, while in others a few imperfectly-developed cells were observed in these areas {Fig. 157, a, c, al). The fine fibrillated texture of Gerlach's network and the small glistening nuclei of the neuroglia appeared to have been replaced by a loose connective tissue, thickly studded with connective tissue corpuscles. Mr. Hardie long ago maintained that con- genital talipes is due to an arrest of development, and that the feet occupy postures similar to those of the embryo. Unusual outgrowths or absence of portions of the grey matter, such as of the tractus intermedio-lateralis, are occasionally met with. Duplica- tions of one of the grey horns for a longer or shorter distance have also been observed. 3. Congenital Deformities zvhich may be recognised during Life. {a) Congenital Enlargement of the Central Canal, a condition which has been variously called hydrorrhachis interna, hydromyelus, or hydromyelus congenitus. In the lighter grades of the congenital affections the central canal in the fcetus is converted into a cavity varying in width from that of an ordinary knitting needle to that of a crow's quill. The canal may extend the entire length of the cord, but is at other times restricted to certain portions, generally the cervical or lumbar enlargement, while the dilatation may occasionally be moniliform, or the anterior and posterior walls may have grown together across the middle giving rise to the appearance of a double canaL The cord does not appear to undergo any abnormal changes apart from the displacement of its various segments occasioned by the great dilatation of the canal. In the higher grade of congenital hydromyelus either the spinal cord disappears entirely, or becomes split into two halves for a greater or lesser distance, while the cavity of the central canal freely communicates with the cavity of the spinal arachnoid ; the hydrorrachis interna is then merged into hydrorrachis externa, as not unfrequently happens in spina bifida. (b) Spina bifida consists of an abnormal accumulation of fluid within the cavity of the spinal arachnoid, associated with a greater or lesser deformity of the vertebral column. As it gives rise to serious symptoms during life it will be subsequently described in detail along with the diseases of the membranes of the spinal cord. 4. Acquired Deformities resulting from Pathological Processes. {a) Syringomyelia, or the pathological formation of cavities, may be caused in various ways. (i.) Cavities are formed by the softening of the central portions of new formations, such as gliomata, gliomyxomata, and gliosarcomata. The tumour is sometimes so completely disintegrated that only a capsule of connective tissue or mere traces of the tumour remain. This softening 100 MOllBID ANATOMY OF THE is sometimes initiated by hcemorrhage into the interior of the tumour. This accident is particularly apt to occur in the teleangiectatic varieties. (ii.) Breaking down and softening of apoplectic foci. (iii.) Central softening in areas of grey degeneration and chronic myelitis. (iv.) Obstruction of lymph channels produced by the pressure of a tumour and other causes (Westphal). Cavities have been formed in the spinal cords of animals subsequent to various injuries, and these have been supposed to have been caused by obstruction of lymph channels (Naunyn and Eichhorst). (b) Hydromyehcs acquisitus, or acquired dilatation of the central canal, may result from the following causes : — (i.) Peri-ependymal myelitis, which consists of a proliferation of the connective tissue surrounding the central canal, may cause secondary dilatation by the shrinking of the newly-formed tissue (Hallopeau). (ii.) Chronic meningitis, by producing adhesions of the pia mater to the dura mater at definite points, may also cause dilatation of the central canal, probably by shrinking of the newly-formed tissue (Simon). (iii.) Obliteration of the canal at one point may lead to dilatation of the neighbouring portions. The cavities vary greatly in size. They may indeed be only a few millimetres in length, or extend the entire length of the cord. Their number also varies ; in many cases one only is found, but at other times a large number of them may be present. They are almost always situated near the centre of the cord, and their relations to the central canal can only be determined by careful examination. The transverse diameter of these cavities may vary from that of a needle to the tip of a man's little finger. On transverse section their form is roundish, oval, or angular, and their contents consist of light and clear or turbid and yellowish fluid. The walls of the cavities may be smooth and firm, and are often lined with a layer of cylindrical epithelium, or they may be rough, ragged, and uneven. Their walls may also be dense, and formed of cirrhotic tissue or of tissue which has undergone grey degeneration, or of the various new formations which have already been described. The symptoms caused by the formation of cavities in the cord depend entirely upon their situation, and no definite disease which can be recognised during life can be ascribed to the presence of these cavities. (II.)— CLASSIFICATION OF THE DISEASES QF THE SPINAL CORD AND MEDULLA OBLONGATA. § 392. The rule which has hitherto been followed in this work is to describe first the simplest and most elementary diseases, and to reserve consideration of the most complicated affections SPINAL CORD AND MEDULLA OBLONGATA. 101 to the last. In no diseases is it more advisable to follow this rule than in those affecting the spinal cord and medulla oblon- gata, with their membranes. The annexed table, in which these diseases are classified, carries with it in the main its own explanation, but it may not be out of place to make a few remarks with regard to the principle adopted in arranging the structural diseases of the nervous organs themselves as dis- tinguished from those of their membranes and vessels, their functional affections, injuries, malformations, and neoplasms. It has already been remarked that the spinal cord may be divided into longitudinal segments, each of which possesses a functional unity, and may be separately diseased. Diseases of one of the functional segments of the cord are called system-diseases or fasciculated diseases, while those involving several of these segments may be called mixed diseases. In the simple system-diseases one functional segment of the cord and medulla oblongata alone is affected; but it sometimes happens that two or more of them become simultaneously or consecutively attacked, and these affections may be called com- pound system-diseases. The system-diseases may be divided into those affecting the grey matter or the poliomyelopathies, and those affecting the white matter or the leucomyelopathies. The poliomyelopathies may be subdivided into the diseases affecting the anterior grey horns, the central grey column, and the posterior grey horns; but the latter is never a true system-disease, being always com- plicated by lesions of other structures, such as the posterior roots and posterior columns. Disease of the central column is also probably never observed as an isolated affection, the promi- nent symptoms being caused by extension of the lesion into the anterior horns; but we shall nevertheless classify some at least of the diseases of the central column amongst the system-diseases. The leucomyelopathies consist theoretically of diseases of the posterior root-zone (locomotor ataxy) ; of the anterior root-zone, disease of which is probably not capable of being separated from disease of the anterior roots and anterior grey horns ; of the column of GoU and the direct cerebellar tract, to both of which, however, no definite symptoms have been observed to attach, and of the pyramidal tract (primary lateral sclerosis). 102 MORBID ANATOMY OF THE The compound system-diseases are probably numerous, but only one of them — amyotrophic lateral sclerosis — is recognised as a distinct type of disease. The annexed diagram (Fig. 158), copied from Charcot, represents the localisation of the lesion on transverse section of the cord in the various system-diseases. In the mixed diseases of the spinal cord and medulla oblon- gata Landry's paralysis is first mentioned, not because it has been proved to be connected with anatomical changes in the cord, but because it is closely allied clinically with the acute forms of central myelitis. The classification adopted of the different forms of acute and chronic myelitis does not require any explanation. Fig. 158. --1 ^ ' --~^^ -^v. I / \ ' r -" -'" ,^^\\ iniSiSSii M^-L, iiP^~- Fig. 158 (After Charcot). Diagram of the Morbid Anatomy of the System-Diseases ijira Mater and Craniid Shmses. — 1. Fair ceretai;; 2, Tentoritun ; 3, 3, Snperior longitndiDal sinns ; 4, laieral sinus ; 5, Internal jugular Tein ; 6, Oodpifcal sinns ; 7, 8, Veins of Galen ; 9 and 10, Superior and inferior petrosal ^ns ; 11, CaTemoos anns ; 12, CSrcolar sinns, which connects the two drcolar annaes together; 13, Ophthahnift Tein, from 15,. the eyeball ; 14, Crista gain of etiunoid bomeL 410 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. form partitions between divisions of the encephalon. These partitions are respectively named the falx cerebri, tentorium, cerehelli, and falx cerehelli. The cranial dura mater is mainly composed of two layers of fibrous tissue, which separate from each other along certain lines, so as to form tubular passages, named sinuses; these transmit the venous blood returning from the brain. The sinuses usually pass from before backwards, and several join opposite the internal occipital protuberance at a spot which is called the torcular Herophili. The blood is drained from the torcular by the lateral sinuses, which terminate in the internal jugular veins. The minute structure of the membranes of the brain is the same as already described in the case of the spinal membranes. § 664. The Arachnoid. — The arachnoid is a delicate and transparent membrane, and between it and the dura mater is a space,, containing a small quantity of limpid serum, which lubricates the smooth opposed surfaces of the two membranes. This space is regarded as equivalent to the cavity of a serous membrane, and is named the arachnoid cavity or suh-dural space. The arachnoid and pia are separated by a distinct space called the suh-arachnoid space. The space contains a limpid cerebro spinal fluid, varying in quantity from two drachms to two ounces. Pacchionian Bodies. — Clusters of granular bodies are observed on each side of the longitudinal sinus imbedded in the dura mater, named Pacchionian bodies. These bodies spring from the arachnoid membrane, and sometimes attain a relatively large size. § 665. Pia Mater. — The pia mater closely invests the whole outer surface of the brain, and dips in the fissures between the convolutions, differing in this respect from the arachnoid, which passes from the summit of one convolution to that of another. A wide prolongation of this membrane passes into the interior of the cerebrum, named the velum interpositum. The pia mater is prolonged along the roots of the cranial and spinal nerves and filum terminale. It is the vascular membrane of ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 411 the brain, and the arteries which pass from it into the substance of the latter are invested by it with a loose funnel-shaped sheath, which opens into the sub-arachnoid space, and contains cerebro-spinal fluid (Key and Retzius). The ventricles of the brain are also supposed to be in free commu- nication with the sub-arachnoid space. THE BEAIN OR ENCEPHALON. The part of the central nervous axis, which is contained within the cavity of the skull, is termed the hrain or encephalon. The brain is conveniently divided into (1), the medulla ob- longata; (2), the pons variolii; (8), the cerebellum; and (4), the cerebrum. § 666. The Medulla Oblongata. — The medulla oblongata is the expanded upper end of the spinal cord, and has already been described. § 667. The Pons Variolii. — The pons rests on the dorsum sellse of the sphenoid bone, and is marked on its inferior aspect by a median longitudinal groove, in which the basilar artery lies; its posterior surface receives the pyramidal tracts and the upward continuation of the anterior root-zones, and the grey matter of the cord; its anterior surface gives origin to the two crura cerebri ; each lateral surface is in relation to a hemisphere of the cerebellum ; the superior surface forms in part the upper portion of the floor of the fourth ventricle, while the corpora quadrigemina rest upon its anterior half. Stntdure of the Pons. — The pons consists of grey and white matter. The greater portion of the grey matter of the pons is an upward continua- tion of the grey matter of the spinal cord and medulla oblongata, which has been already described. In addition to the grey matter on the floor of the fourth ventricle, there is a considerable quantity interposed between the transverse fibres of the pons. The transverse fibres derived from each lateral lobe of the cerebellum appear to terminate in the interposed grey matter of the opposite half of the pons. The white matter of the pons consists of longitudinal and transverse fibres. The longitudinal fibres are the upward continuations of the anterior pyramids of the medulla, the anterior root-zones of the cord, and probably also fibres ascending from the olivary body. The longi- tudinal fasciculi are also reinforced by fibres arising in the pons itself. 412 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The transverse fibres go from one hemisphere of the eerebellum to that of the opposite side, although the fibres are probably interrupted in the pons by interposed grey matter. These fibres, therefore, constitute the commissural or connecting arrangement, by means of which the two hemispheres of the cerebellum become anatomically continuous with one another. THE CEEEBELLUM. § 668. — The cerebellum occupies the iDferior occipital fossae. It consists of two lateral hemispheres joined together by a median portion called the vermiform process. On the superior surface of the cerebellum this is a mere elevation, but on its inferior surface it forms a well-marked projection, named the inferior vermiform process. This process lies at the bottom of a deep fossa (vallecula), which is prolonged to the posterior border of the cerebellum, and forms there a deep notch, in which the falx cerebelli is lodged. The Peduncles. — The cerebellum is connected below with the medulla oblongata by the two restiform bodies which form its inferior peduncles. The crossed connection of the fibres of the inferior peduncles of the cerebellum with the olivary bodies has already been described. The cerebellum is connected with the corpora quadrigemina and crura cerebri by two superior peduncles. The greater portion of the fibres of the superior peduncles decussate in the upper end of the pons and in the tegmenta, the fibres of one side becoming connected with the red nucleus of the tegmentum of the opposite side. The trans- verse fibres of the pons form the middle peduncles of the cerebellum. Folia. — The surface of the cerebellum consists of numerous lamina} or folia, which are separated by fissures or sulci of diffe- rent depths. Fissures. — The great horizontal fissure begins behind the middle peduncles, passes horizontally backwards round the circumference of the cerebellum, dividing its tentorial and occipital surfaces. From this primary fissure numerous others proceed, and some that are constant in their position and deeper than the rest have been described as separating the cerebellum into lobes. Lohes. — The tentorial surface is subdivided into two smaller ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 413 lobes, named anterior superior and posterior superior. On the occipital surface each hemisphere is subdivided from behind forwards into the posterior inferior lohe, the slender lohe, the hiventral lohe, and the flocculus. Immediately internal to the biventral lobe is the amygdala or tonsil, which forms the lateral boundary of the anterior part of the vallecula. The infe- rior vermiform process is subdivided into a posterior part or pyramid, an elevation or uvula situated between the two tonsils, and an anterior pointed process or nodule. Stretching between the two flocculi, and attached midway to the sides of the nodule, is a thin, white, semi-lunar-shaped plate of nervous matter, called the posterior medullary velum, whilst the layer of grey matter stretching between the uvula and tonsil on each side is called the furrowed band. § 669. Internal Structure. — The cerebellum consists of both grey and white matter. The grey matter forms the exterior or cortex, while the white forms the interior of the organ. A vertical section through the cerebellum presents an arborescent appearance known by the name of arbor vitce. Independent masses of grey matter are found in the interior of the cerebellum. If the hemisphere be cut through to the outer side of the median lobe, a nucleus of grey matter is observed similar in its arrange- ment to the olivary body, and named the corpus dentatum. It encloses Fig. 190. Fig. 190 (From Turner). The Occipital Surface of the Cerebellum.— a, Vallecula; 6, Pyramid ; c, Uvula ; d. Nodule ; e, e, Margin of tentorial surface ; /, /, Great horizontal fissure ; g, g, Posterior inferior lobes ; h, h, Slender lobes ; k,k, Biventral lobes ; I, Tonsil; m, Flocculus; ri, Posterior medullary velum; 0, Cut surface from which the left tonsil has been detached. 414 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. white fibres which leave the interior of the corpus at its inner and lower aides. Stilling has described two grey masses situated in the anterior end of the inferior vermiform process which he named roof nuclei. The white matter is for the most part continuous with the fibres of the peduncles of the cerebellum. The fibres of the inferior peduncles pass upwards to join the grey matter of the superior surface of the cerebellum, especially in the median lobe. They are also connected with the corpus dentatum and roof nuclei. Those of the superior peduncles descend from the corpora quadrigemina and reach the grey cortical matter, more espe- cially that of the inferior surface of the cerebellum, and they are also con- nected with the corpus dentatum. The fibres of the middle peduncles terminate chiefly in the cortex of the lateral lobes. The cerebellum also contains fibres which connect difierent parts of its grey matter with one another, named fibrce proprice. Stilling describes a median fasciculus, the fibres of which connect the superior and inferior vermiform processes. Other fibres cross the median plane to unite symmetrical regions of the lateral lobes. Meynert describes a cerebellar origin of the auditory and fifth nerves. Minute Structure. — The grey matter of the cortex is divided into an external grey or cellular layer, and an internal rust-coloured layer of about equal thickness. The external layer consists of a delicate matrix contain- ing cells and fibres. Most of the fibres have a direction at right angles to the surface, the majority of them being the processes of Purkinje's cells, to be immediately described. Of the cells some are small, and appear to belong to the connective-tissue matrix, while others are larger, and probably connected with the processes of Purkinje's cells. The inner part of the external layer contains fibres which run parallel with the surface. The inner or granule layer consists of granule-like corpuscles, which lie in dense groups in a gelatinous matrix, containing a plexus of fine nerve fibres. Some are round, while others are angular and possess a protoplasmic envelope with processes, which are supposed to be connected with the plexus of fine nerve fibres amongst which they lie. The cells of Purkinje lie in a single layer, between the outer and inner layers of the cortex. Most of them are flask-shaped bodies, containing a spherical nucleus and nucleolus. The long axis of the cell is generally directed at right angles to the surface. From the external surface of the cells two processes are given ofi" ; these pass out towards the surface and divide repeatedly in their course. The finer subdivisions of these pro- cesses have been said to curve back towards the granule layer, where, according to Boll, they form a network of extreme minuteness, from which it is believed that nerve fibres arise. From the inner end of the cell another fibre is given ofi"; it is unbranched, passes into the granule layer, and is supposed to be continuous with the axis cylinder of a nerve fibre. The medullary centre consists of nerve fibres arranged in parallel or interlacing bundles. They form the central stem of the folia, whence ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 415 they radiate into the cortex. They disappear in the granule layer, and are commonly believed to be continuous with the inner processes of Purjdnjd's cells. THE CEREBRUM. § 670. The cerebrum constitutes the largest division of the encephalon, and lies above the level of the tentorium. It con- sists of a narrow constricted portion — the crura — of certain basal ganglia — the corpora quadrigemina, optici thalami, and corpora striata — and of an upper expanded portion — the cere- bral hemispheres. § 671. Exterior of the Cerebrum. — The cerebrum is ovoid in shape and presents superiorly, anteriorly, and posteriorly a deep median longitudinal fissure, which subdivides it into two hemispheres. The two hemispheres are connected across the median plane by the corpus callosum. The outer surface of each hemisphere is convex, and adapted in shape to the con- cavity of the inner table of the cranial bones. Its inner sur- face is flat, and is separated from the opposite hemisphere by the falx cerebri. The under surface, where it rests on the tento- rium, is concave, and is separated by that membrane from the cerebellum and pons. From the front of the pons two strong white bands, the crura cerebri or cerebral peduncles, pass for- wards and upwards to enter the basal ganglia of their respective hemispheres. The optic tracts wind round each crus, and con- verge in front to form the optic commissure from which the two optic nerves arise. The crura cerebri, optic tracts, and optic commissure enclose a lozenge-shaped space which includes from behind forwards the posterior perforated space, the corpora albicantia, and the tuber cinereum, from which the infundi- bulum projects to join the pituitary body. Immediately in front of the optic commissure is a grey layer, the lamina cinerea or lamina terminalis of the third ventricle; and between the optic commissure and the inner end of each Sylvian fissure is a grey spot perforated by small arteries, the anterior per- forated space. The peripheral part of each hemisphere consists of grey matter, and exhibits a characteristic folded appearance, known as the convolutions or gyri of the cerebrum. The convolutions are separated from each other hy fissures or sulci, some of 416 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. which are considered to subdivide the hemispheres into lobes, whilst others separate the convolutions of each lobe from each other. * Fig. 191. 2 Tig. 191 (From Henle's Anatomie). Base of the Srain.—F, Pons; Tho, Optic thalamus ; Lpp, Posterior perforated space ; Jn, Island of Reil. Tbo, Olfactory bulb. Let, Lamina cinerea. Tc, Tuber cinereum. CcP, Knee of the corpus callosum. Pec, Peduncles of the corpus callosum. Cba, Commissure of the corpus callosum. Spa, Anterior perforated space. Cc, Corpora albicantia. Gf, Gyrus fornicatus. T, Tegmentum. B, Crusta. Sr, Substantia reticularis. Mo, Medulla oblongata. The Roman letters indicate the corresponding cranial nerves : I, Olfactory nerve ; Ji, Olfactory bulb ; II, Optic nerve ; IIS Optic tract ; *, Sylvian fissure ; **, the point of the temporo-sphenoidal lobe dravm back to show the continuity of this lobe with the posterior convolution of the Island of Reil. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 417 § 672. Lobes of the Cerebrum. — They are five in number, named respectively frontal, parietal, occipital, temporo- sphenoidal, and central. The divisions between these lobes are marked partly by certain conspicuous fissures, and partly by artificial lines. § 673, The Primary Fissures. — The Sylvian fissure is the first to appear in the development of the hemisphere. It passes obliquely along the outer surface of the hemisphere from before backwards, and upwards. In man it divides into two rami — the posterior or horizontal (Fig. 192, S'), and the ascending or anterior (Fig. 192, S"). The portion included between these two branches receives the name of the operculum, and forms the roof of the central lobe or Island of Reil. Below the fissure of Sylvius lies the temporo- sphenoidal lobe, and above and in front of it the parietal and frontal lobes. The frontal is separated from the parietal lobe by the fissure of Rolando (Fig. 192, c) or Central Sulcus. It extends from the longitu- dinal fissure obliquely, downwards and forwards, along the outer surface of the hemisphere towards the Sylvian fissure. The parieto-occipital fissure commences at the longitudinal fissure, about two inches from the posterior end of the hemisphere. It passes down the inner surface of the hemisphere, and also trans- versely outwards for a short distance on the outer surface, and separates the parietal and occipital lobes from each other. § 674. Secondary Fissures and Convolutions. — The temporo- sphenoidal lobe presents on the outer surface of the hemispheres three parallel convolutions, named the superior (Fig. 192, Tl), middle (Fig. 192, T2), and inferior temporo-sphenoidal (Fig. 192, T3) convolutions. — The fissure which separates the superior and middle of these convolutions is called the parallel fissure. The occipital lobe also consists of three parallel convolutions, named superior (Fig. 192, 01), middle (Fig. 192, 02), and inferior (Fig. 192, 03) occipital convolutions. The frontal lobe consists of three convolutions arranged in parallel tiers from above downwards, and named superior (Fig, 192, Fl), middle (Fig. 192, F2), and inferior (Fig. 192, F3) frontal convolutions. These are prolonged anteriorly to the BB 418 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. orbital surface of the frontal lobe, and terminate posteriorly in the convolution which forms the anterior boundary of the fissure of Rolando, named the ascending frontal convolution {Fig. 192, A). The secondary fissures which separate the superior, middle, and inferior frontal convolutions from one another are the supero- frontal (Fig. 192, /I), and the in fero -frontal {Fig. Fig. 192. Fig. 192 lEcker). Lateral View of the Human Brain. — F, Frontal lobe. P, Parietal lobe. O, Occipital lobe. T, Temporo-sphenoidal lobe. S, Fissure of Sylvius, S' Horizontal, S" Ascending ramus of the same. _ c, Sulcus cen- tralis, or fissure of Rolando. A, Anterior central or ascending frontal con- volution. B, Posterior central or ascending parietal convolution. Fj Superior, Fa Middle, and Fg Inferior frontal convolutions, f^ Superior and /j Inferior frontal sulcus ; fa Sulcus prae-centralis. Pj Superior parietal or postero-parietal lobule ; Pa Inferior parietal lobule, viz. P.^ Gyrus supra-marginalis, P^' Gyrus angularis. ip, Sulcus intra-parietalis. cm, Termination of the calloso-marginal fissure. Oi First, O2 Second, O3 Third occipital convolutions. _ po, Parieto- occipital fissure. 0, Sulcus occipitalis transversus ; 0^ Sulcus occipitalis longi- tudinalis inferior. T^ First, Ta Second, T, Third temporo-sphenoidal convo- lutions, ti First, «2 Second temporo-sphenoidal fissures. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 419 192, /2), while the continuity of the three frontal convo- lutions with the ascending frontal one is interrupted by the antero-parietal sulcus, or Sulcus Proe-centralis {Fig. 192, /3). The ascending ramus of the fissure of Sylvius [Fig. 192, S") also interrupts the continuity of the inferior frontal with the ascend- ing frontal convolution. Fig. 193. Fig. 193 (After Ecker and Duret). View of the Brain from below. Fl, Grynis Rectus. F2, Middle frontal convolution. F3, Inferior frontal convolution. /4, Sulcus olfactorius. /5, Sulcus orbitalis. 2*2, Second or middle temporo-sphe- noidal convolution. T3, Third or inferior temporo-sphe- noidal convolution. Fi, Gyrus occipito-temporalis lateralis (lobulus fusiformis). T5, Gyrus occipito-temporalis medialis (lobulus lingualis). ti, Sulcus occipito-temporalis inferio t'S, Sulcus temporo-sphenoidalis inferior. t2, Sulcus temporo-sphenoidalis m©" dialis. po, Parieto-occipital fissure. oc, Calcarine fissure. ff, Gyrus hippocampi. U, Gyrus uncinatus. Ch, Optic chiasma. cc, Corpora albicantia. KK, Crura cerebri. V, Corpus callosum. 420 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The orbital surface or orbital lobule presents two fissures — the olfactory sulcus, -which runs parallel with the longitudinal fissure and lodges the olfactory bulb, and the orbital sulcus {Fig. 193, /5), which lies in the centre of the lobule and is often triradiate. The straight convolution {Fig. 193, Fl) lies between the longitudinal fissure and the olfactory sulcus, and is con- tinuous at its anterior extremity with the superior frontal convolution. Three convolutions are sometimes described as lying around the orbital sulcus, named, according to their positions, the internal, the anterior, and the posterior orbital convolutions. The parietal lobe presents several convolutions. The most anterior is the ascending parietal convolution {Fig. 192, B), which lies immediately behind the fissure of Rolando, and is bounded posteriorly by a sulcus termed the intra-parietal sulcus {Fig. 192, ip). The postero-parietal convolution or superior parietal lobule {Fig. 192, PI) springs from the upper end of the back of the ascending parietal convolution, and forms the boundary of the longitudinal fissure, extending as far back as the parieto-oceipital fissure. The supra-marginal convo- lution {Fig. 192, P2) springs from the lower end of the ascend- ing parietal convolution at its posterior aspect, and arches round the posterior extremity of the Sylvian fissure. The angular gyrus {Fig.l92,'P2') is continuous with the supra-marginal con- volution, and bends round the posterior extremity of the parallel fissure. The supra-marginal convolution and angular gyrus have together been described as the inferior parietal lobule (Ecker), or the convolutions of the parietal eminence (Turner). They occupy the hollow in the parietal bone which corresponds with the parietal eminence. The occipital is connected with the parietal lobe by two annectant or bridging gyri. The superior annectant gyrus passes between the postero-parietal and the superior occipital convolutions, whilst the second annectant gyrus connects the middle occipital with the angular gyrus. Two annectant gyri also pass from the inferior occipital convolution to the lower convolutions of the temporo-sphenoidal lobe. The central lobe, or Island of Reil, lies deeply within the fissure of Sylvius, being invisible except when the lips of the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 421 fissure are separated. It consists of about six short, straight convolutions (gyri operti), which radiate outwards from the anterior perforated space. The anterior convolution is con- tinuous with the adjacent posterior orbital convolution, while the posterior convolution joins the temporo- sphenoidal lobe. Externally, the island of Reil is separated by a deep sulcus from the contiguous convolutions of the operculum, and it covers the lenticular nucleus of the corpus striatum. The small convolutions which lie behind the parieto-occipital fissure form the internal convolutions of the occipital lobe, named the internal occipital lobule, or cuneus {Fig. 194, Oz). Those which lie immediately in front of the internal part of the parieto-occipital lobule and between it and the curved posterior extremity of the calloso- marginal fissure are called Fig. 194. Fig. 194 (Ecker). View of the Median J sped of the Bight Hemisphere of the Human Brain. — OC, Corpus callosum, longitudinally divided. Gf, Gyrus fornicatus. H, Gyrus hippocampi, h, Sulcus hippocampi. U, Uncinate gyrus, cm, Sulcus calloso-marginalis. Fi, Median aspect of the first frontal convolution. 0, Terminal portion of the sulcus centralis, or fissure of Rolando. A, Anterior ; B, Posterior central convolution. Pi", Prsecuneus. Oz, Cuneus. Po, Parieto- occipital fissure, o, Sulcus occipitalis transversus. oc, Calcarine fissure, oc', Superior ; oc", Inferior ramus of the same. D, Gyrus descendens. _ T4, Gyrus occipito-temporalis lateralis (lobulus fusiformis). T», Gyrus occipito- temporalis medialis llobvilus lingualis). 422 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. the prcBcuneus or quadrilateral lobule {Fig. 194, Pi"). The paracentral lobule lies immediately in front of the prsecuneus. It consists of the upper extremities of the ascending frontal and parietal convolutions, viewed from the internal surface of the hemisphere. It is cutomary to name the convolution which Fig. 195 ( From Henle's Anatomie ). Internal View of the Hemisphere of the Oerebrum. CcP, Knee of the callosum. Ftp, Posterior transverse fissure, Vq, Fourth ventricle. Mo, Medulla oblongata. P, Pons. Cca, Corpora caudicantia. Tc, Tuber cinereum. H, Pituitary body. II', Optic tract. II, Optic nerve. Let, Lamina cinerea, CcP, Corpus callosum. Ccl*, Splenium of the corpus callosum. SI, Septum lucidum. Com, Median commissure of the third ventricle. SM, Sulcus Monroi. Cop, Posterior commissure of the third ventricle. Cn, Pineal gland. Coa, Anterior commissure of the third Lq, Corpora quadrigemina. ventricle. A, Aqueduct of Sylvius. Cba, Commissure of the corpus cal- Fta, Anterior transverse fissure. losum. Vma, Anterior medullary velum CclS Eostrum. Cbl, Cerebellum. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 423 extends forwards from the parieto-occipital fissure along the margin of the longitudinal fissure to the anterior extremity of the hemisphere, and which then turns back to the anterior perforated space, the marginal convolution. The internal is not divided into lobes like the external surface, but the convolutions may be studied in connection with the corpus callosum and with certain fissures situated in this surface. The parieto -occipital fissure (Fig. 194, Po) is continuous with the fissure of the same name on the external surface. It ex- tends downwards and forwards, and blends with the calcarine fissure. The calcarine fissure {Fig. 194, oc) commences at the posterior extremity of the hemisphere, usually in a bifurcated manner, and extends forwards to terminate beneath the pos- terior extremity of the corpus callosum. It marks the position of the calcar avis or hippocampus minor in the posterior cornu of the lateral ventricle. The calloso-marginal fissure (Fig. 194, cm) commences beneath the anterior extremity of the corpus callosum, and passes forwards, upwards, backwards, round the corpus callosum, terminating behind the superior extremity of the ascending parietal convolution. The convolution which immediately bounds the corpus callosum is termed the gyrus fornicatus (Fig. 194, Gf). It begins at the anterior perforated space, turns round the an- terior end of the corpus callosum, extends parallel to its upper surface, and then turns round its posterior end. It is sepa- rated from the corpus callosum by the callosal fissure, and from the marginal convolution by the calloso-marginal fissure. The posterior end of the gyrus fornicatus curves downwards and then forwards under the name of gyrus uncinatus, or gyrus hippocampi (Fig. 194, H), to the tip of the inner sur- face of the temporo-sphenoidal lobe. The uncinate gyrus ends anteriorly in a crook-like extremity, or crochet, named the uncus gyri fornicati, or subiculum cornu ammonis (Fig. 194, U). The gyrus is separated anteriorly by a narrow-curved fissure, called hippocampal or dentate fissure, from a white band named the taenia hippocampi. This band possesses a free-curved border, round which the pia mater enters the lateral ventricle through the great transverse fissure of the 424 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. cerebrum. The grey matter of the gyrus hippocampi termi- nates at the bottom of the hippocampal fissure in a well-defined dentated border named the fascia dentata. The hippocampal fissure marks the position of an eminence in the descending cornu of the ventricle called the MppocaTnpus major. Running along the internal aspect of the occipital and tem- poro-sphenoidal lobes is a fissure termed the collateral, which marks the position of the collateral eminence in the lateral ven- tricle. It separates two convolutions from each other which connect the occipital and temporo-sphenoidal lobes with each other, and are therefore named the occipito-temporal convo- lutions {Fig. 194, T4, T5). The upper of these is termed the gyrus occipito-temporalis medialis, or lingual lobule (T5); while the lower is named the gyrus occipito-temporalis lateralis, or lobulus fusiformis (T4). §675. KELATIONS OF THE CONVOLUTIONS TO THE SKULL. The relations of the primary fissures and convolutions of the brain with relation to the skull have been investigated by Broca, Fdrd, Turner, and others. The following is an abstract of Turner's conclusions : — Befinite Landmarks on the Surface of the Skull. — The following struc- tures and markings are easily recognised on the skull. The external occipital protuberance {Fig. 196, o), the parietal (P) and frontal (F) emi- nences, and the external angular process of the frontal bone (A), the coronal (c) and lambdoidal {I), squamous (s), squamoso-sphenoid {ss), and parieto -sphenoid sutures {ps), and the curved line of the temporal ridge {t). Primary Areas oj the Skull. — The coronal suture (c) forms the posterior boundary of the frontal area. A vertical line {Fig. 196, 2) drawn from the squamous suture (s) upwards through the parietal eminence (P) to the sagittal suture lies almost parallel to the coronal suture, and subdivides the parietal region into an antero-parietal {Fig. 196, SAP + lAP) and di. postero-parietal area, {Fig. 196, SPP + IPP). The occipital region lies between the lambdoidal suture {I) and the occipital protuberance (o), with the superior curved line extending from it {Fig. 196, o). Secondary Areas of the Skull. — These four primary divisions of the skull may be subdivided into secondary areas. The temporal ridge {Fig. 196, f) starting from the external frontal process curves backwards across the frontal (A), antero-parietal, and post-parietal areas to the internal angle of the occipital bone, and subdivides each of these regions into an upper and ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 425 a lower area. The upper frontal area, which includes all the frontal regions above the temporal ridge, is again divided by a line drawn vertically upwards and backwards from above the orbit through the frontal eminence to the coronal suture {Fig. 196, c). This line divides the upper frontal area into a super o- frontal (SF) and a mid-frontal area (MF). Two other areas remain to be described. These are concealed by the temporal muscle, and are limited superiorly by the squamoso-parietal, sphenoido-parietal, and fronto-sphenoidal sutures. The lines of the sutures naturally divide this area into a squamoso-temporal (Sq) and ali-sphenoidal area (AS). The following then are the secondary areas of the skull : Superior Frontal (SF), Middle Frontal (MF), Inferior Frontal (IF), Upper Antero-Parietal (SAP), Lower Antero- Parietal (lAP), Upper Postero- Parietal (SPP), Lower Postero-Parietal ('IPP), Occipital (0), Squamoso- Temporal (Sq), and Ali- Sphenoidal (AS). Fig. 196. Fig. 196 (Ferrier). Lateral View of the Human Skull.— A, The external angular process of the frontal bone. F, The frontal eminence. P, The parietal eminence, o, The occipital protuberance, c, The coronal suture. I, The lambdoidal suture, s, The squamous suture, i, The temporal ridge, /s, The fronto-sphenoid suture, ps. The parieto-sphenoid suture, ss. The squamoso-sphenoid suture. pm. The parieto-mastoid suture. 1, Frontal line. 2, Parietal line. SF, MF, IF, The supero-, mid-, and infero-frontal subdivisions of the frontal area. SAP, The supero-antero-parietal area. lAP, The infero-antero-parietal area. SPP, The supero-postero-parietal area. IPP, The infero-postero-parietal area. O, The occipital area, Sq, The squamoso-temporal area. AS, The ali-sphenoid area. 426 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. RELATIONS OF THE CONVOLUTIONS AND FISSURES OF THE BRAIN TO THE AREAS OF THE SKULL. § G76. The fissure of Sylvius {Fig. 197, SS) commences behind the posterior border of the lesser wing of the sphenoid, and courses upwards and backwards below the greater wing of the sphenoid, where it articulates with the anterior inferior angle of the parietal bone, and then appears in the lower part of the inferior antero-parietal region. The fissure of Rolando {Fig. 197, B,) lies in the antero-parietal region, both in its superior and inferior divisions, its upper extremity being as much as two inches and its lower one and a half inch behind the respective ends of the coronal suture. The coronal suture does not, therefore, correspond to the boundary between the frontal and parietal lobes of the brain. The parieto-occipital fissure is situated on an average about 07 to 08 inch in front of the apex of the lambdoidal suture {Fig. 197, PO). Contents of the Respective Areas. The froibtal area is occupied by the frontal lobe, but does not cover the whole of it, the posterior extremities of the three frontal convolutions lying behind the coronal suture. The frontal area therefore corresponds to the part of the frontal lobe supplied by the anterior cerebral artery, and which is not excitable to stimulation. The superior, middle, and in- ferior frontal areas of the skull correspond respectively to the superior, middle, and inferior frontal convolutions, with the exception of their posterior extremities. The upper antero-parietal area {Fig. 197, SAP) contains the upper two-thirds of the ascending frontal *(AP) and ascending parietal (S) con- volution, and the posterior extremities of the superior (I'Sin.) and middle frontal (1 /yin.) convolutions. At the upper posterior angle of this area part of the postero-parietal lobule is visible, and below this, part of the supra-marginal lobule may appear. The lower antero-parietal area {Fig. 197, lAP) contains the lower third of the ascending parietal (lin.) and ascending frontal (AP) convolutions, and the posterior extremities (lin.) of the inferior frontal convolution. A small portion of the supra-marginal gyrus is visible at the upper posterior angle of this area, and below it a small portion of the superior temporo-sphenoidal convolution. The upper postero-parietal area {Fig. 197, SPP) contains the greater part of the postero-parietal lobule. Below it lies the upper portion of the angular gyrus (SPP), and part of the supra-marginal gyrus (X j. Poste- riorly the annectant gyri blend with the occipital lobe. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 427 The lower postero-parietal area {Fig. 197, IPP) contains part of the supra-marginal gyrus, and behind it part of the angular gyrus, and below this the posterior or upper ends of the temporo-sphenoidal convolutions. The occipital area {Fig. 197, 0) indicates the situation of the occipital lobe, but is not co-extensive with it, inasmuch as a portion extends ante- riorly beyond the lambdoidal suture into the postero-parietal area. The squanioso-temporal area {Fig. 197, Sq) contains the greater portion of the temporo-sphenoidal convolutions, but the superior temporo- sphenoidal convolution ascends into the lower parietal areas. Fig. 197. Fig. 197 (Turner). Diagram showing the Relations of the Convolutions of the Skull. E, The fissure of Rolando, which separates the frontal from the parietal lobe. PC, The parieto -occipital fissure between the parietal and occipital lobes. SS, The fissure of Sylvius, which separates the temporo-sphenoidal from the frontal and parietal lobes. SF, MF, IF, The supero, mid-, and infero-frontal subdivisions of the frontal area of the skull ; the letters are placed on the superior, middle and inferior frontal convolutions. SA.P, The supero-antero- parietal area of the skull : S is placed on the ascending parietal convolution, AP on the ascending frontal convolution. lAP, The infero-antero-parietal area of the skull : I is placed on the ascending parietal, AP on the ascending frontal convolution. SPP, The supero-postero-parietal area of the skull : the letters are placed on the angular convolution. IPP. The infero-postero-parietal area of the skull : the letters are placed on the mid-temporo-sphenoidal convo- lution. X , The convolution of the parietal eminence, or supra-marginal gyrus. 0, The occipital area of the skull : the letter is placed on the mid-occipital convolution. Sq, The squamoso-temporal region of the skull : the letters are placed on the mid-temporo-sphenoidal convolution. AS, The ali-sphenoid region of the skull : the letters are placed on the tip of the supero-temporo- sphenoidal convolution. 428 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The ali-sphenoidal area {Fig. 197, AS) contains the lower or anterior extremity of the temporo-sphenoidal lobe. The central lobe, or Island of Reil, does not conae to the surface, but lies deep in the fissure of Sylvius, and is concealed by the convolutions which form the margin of that fissure anteriorly. It lies opposite the upper part of the great wing of the sphenoid and its line of articulation with the anterior inferior angle of the parietal and the squamous part of the temporal. The convolutions situated on the internal aspect of the hemisphere are altogether out of relation to the surface of the skull. The deep-seated position and direction of the hippocampal region are superficially indicated by the convolutions of the temporo-sphenoidal lobes, contained chiefly in the inferior postero-parietal, squamoso-temporal, and ali-sphenoidal areas. #677. INTERNAL PARTS OF THE CEREBRUM. The anatomy of the cerebrum is most conveniently studied by successive horizontal sections. Centrum Ovale. — A horizontal section made half an inch above the corpus callosum displays the white matter of each hemisphere surrounded on all sides by the grey matter of the convolutions. The white central mass in each hemisphere was named by Vicq. d'Azyr the centrum ovale minus. A section made at the level of the corpus callosum shows that the white substance of that part is continuous with the central white sub- stance of each hemisphere. The large white medullary mass thus displayed is named the centrum ovale majus. The Corpus Callosum connects the centres of the two hemispheres, and it approaches nearer their anterior than their posterior extremities. It terminates behind in a free rounded end — the splenium, whilst in front it forms a knee- shaped bend, and passes downwards and backwards as far as the lamina cinerea. It is thicker behind than in front, the middle part being the thinnest. It consists of bundles of nerve fibres, almost the whole of which pass transversely between the two hemispheres. The fibres may be traced into the white cores and grey matter of the convolutions, and apparently connect corresponding convolutions in the opposite hemispheres. A few fibres run longitudinally on the surface of the corpus callosum, named the strice longitudinales or nerves of Lancisi. Topography of the Centrum Ovale. — A systematic nomen- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 429 clature of the various parts of the centrum ovale has been devised by Pitres. His system consists in making vertical sections of the brain at definite points, and naming the various parts of the medullary substance exposed in each section. A vertical section of the hemisphere at right angles to its longi- tudinal axis in the prse-frontal region gives the prce-frontal section {Fig. 198). The next section is made two centimetres Fig. 198. Fig. 198 (After Pitres). Prce-frontal Bection.—l, 2, 3, First, second, and third frontal convolutions. 4, Orbital convolutions. 5, Convolutions on the internal aspect of the frontal lobe. 6, Prse-frontal fasciculi of the centrum ovale. Fig. 199. Fig. 199 (After Pitres). Pedunculo-frontal Section.— 1, 2, 3, First, second, and third frontal convolutions. 4, Anterior extremity of the insular lobe. 5, Posterior extremity of the orbital convolutions. 6, Superior pedunculo-frontal fasciculus. 7, Middle pedunculo-frontal fasciculus. 8, Inferior pedunculo-frontal fasciculus. 9, Orbital fasciculus. 10, Corpus callosum. 11, Caudate nucleus. 12, Internal capsule. 13, Lenticular nucleus. 430 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. iu front of the fissure of Rolando and passes through the bases of the three frontal convolutions, and is named the pedunculo- frontal section {Fig. 199). The medullary substance in this section is subdivided into a superior, middle, and inferior pedunculo-frontal fasciculus, corresponding with the respective frontal convolutions. The next section is made through the ascending frontal convolution, parallel with the fissure of Rolando, and is named the frontal section. It also passes through a small portion of the sphenoidal lobe. The medullary substance of this section is also subdivided into superior, middle, and inferior frontal fasciculi {Fig. 200), The fourth section Fi«. 200. Fig. 200 (After Pitres). Frontal Section. — 1, Ascending frontal convolution. 2, Insular lobule. 3, Sphenoidal lobe. 4, 5, 6, Superior, middle, and inferior frontal fasciculus. 7, Sphenoidal fasciculus. 8, Corpus callosum. 9, Caudate nucleus. 10, Optic thalamus. 11, Internal capsule. 12, Lenticular nucleus. 13, External capsule. 14, Claustrum. is carried through the ascending parietal convolution, and is named the parietal section. It is subdivided into superior, middle, and inferior parietal fasciculi {Fig. 201). The next is the pedunculo -parietal section, made by dividing the hemi- sphere three centimetres behind the fissure of Rolando, and cutting the superior and inferior parietal lobules. It is sub- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. Fig. 201. 431 Fig. 201 (After Pitres). Parietal Section. — 1, Ascending parietal convolution. 2, Insular lobe. 3, Sphenoidal lobe. 4, Superior parietal fasciculus. 5, Middle parietal fasciculus. 6, Inferior parietal fasciculus. 7, Sphenoidal fasciculus. 8, 9, 10, 11, 12, 13, 14, as in the preceding figure. Fig. 202. Fig. 202 (After Pitres), Pedunculo-parietal Section.— 1, Superior parietal lobule. 2, Inferior parietal lobule. 3, Sphenoidal lobe. 4, Superior pedunculo-parietal fasciculus. 5, Inferior pedunculo-parietal fasciculus. 6, Sphenoidal fasciculus. 7, Corpus callosum. 8 and 10, Caudate nucleus. 9, Optic thalamus. 432 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. divided into superior and inferior pedunculo-parietal and sphenoidal fasciculi (Fig. 202). The last is the occipital section (Fig. 203) in which no separate fasciculi are distinguished. Flu. 203. Fig. 203 (After Pitres). Occipital Section.— 1, Occipital convolutiona. 2, Occipital fasciculi of the centrum ovale. Lateral Ventricles. — The lateral ventricle is divided into a central space or body, and three curved prolongations or cornua. The anterior cornu extends forwards and outwards into the frontal lobe, the posterior curves backwards, outwards, and in- wards into the occipital lobe, and the descending cornu curves backwards, outwards, downwards, forwards, and inwards, behind and below the optic thalamus into the temporo-sphenoidal lobe. On the floor of the central space may be seen from before backwards the caudate nucleus, and to its inner and posterior part a small portion of the optic thalamus, whilst between the two is a curved flat band, the tcenia semicircularis. The choroid plexus rests on the upper surface of the optic thalamus, and immediately internal to it is the free edge of the fornix. The anterior end of the caudate nucleus projects into the anterior cornu, while the posterior cornu has an elevation on its floor, named the hippocampus minor, and the eminentia col- lateralis lies between the posterior and descending cornua. The hippocampus major extends along the floor of the descending cornu, and terminates below in a nodular end, the pes hippo- campi. Along its inner edge is a narrow white band prolonged from the posterior pillar of the fornix, named the tcenia hippo- campi. If the taenia be drawn aside the hippocampal fissure ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 433 is exposed, at the IJottom of which the grey matter of the gyrus hippocampi may be seea to form a serrated border, named the fascia dentata. The choroid plexus enters the descending cornu through the great transverse fissures of the brain between the tsenia hippocampi and optic thalamus. The lateral ven- tricle is lined by cylindrical epithelium, which rests on a layer of neuroglia, and is in many parts ciliated. This lining is con- tinuous with that of the third ventricle through the foramen of Monro, the lining of the latter being continuous with that of the fourth ventricle through the aqueduct of Sylvius. A little fluid • is contained in the cerebral ventricles. Septum Lwcidum. — If the corpus callosum be divided trans- versely about its middle, and the two halves reflected forwards and backwards respectively, the fornix and septwTn lucidum are exposed. This septum extends vertically between the corpus callosum above and the fornix below. It consists of two layers of grey matter, having an interval between them containing fluid, and covered by an epitheliated membrane. This space is the Jifth ventricle. The fornix is an arch-shaped band of nerve fibres which ex- tends in the antero-posterior direction, its anterior end form- ing the anterior pillars, its posterior the posterior pillars, and its body the summit of the arch. It consists of lateral halves, but at the summit of the arch the two are joined together to form the body. The anterior pillars are separate from one another; they descend in front of the third ventricle to the base of the cerebrum, where they form the corpora alhicantia, and then enter the substance of the optic thalamus. The posterior pillars are also separate ; each curves downwards and outwards into the descending cornu of .the ventricle, and forms the free border of the hippocampus major, which is named the taenia hippocampi. The velum, interpositum is a fold of pia mater which passes into the interior of the hemispheres through the great trans- verse fissure. It is triangular in shape, the base is in a line Avith the posterior end of the corpus callosum, the lateral mar- gins are fringed by the choroid plexuses, and the apex, where the choroid plexuses blend with each other through the foramen of Monro, lies behind the anterior pillars of the fornix. CC 484 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. The choroid plexuses consist of highly vascular folds of membrane, and the epithelium of the ventricles is continued over their surface. These plexuses contain the small choroidal arteries, and supply the corpora striata, the optici thalami, and corpora quadrigeraina, the blood from these bodies being re- invned hy the veins of Galen. If the velum interpositum be raised from before backwards, the optic thalami, third ven- tricle, pineal gland, and corpora quadrigemina are exposed {Fig. 204). The third ventricle is a cavity situated in the mesial plane, between the optici thalami ; its roof is formed by the velum interpositum and the body of the fornix, its floor by the pos- terior perforated space {"pons Tarini), the corpora albicantia, the tuber cinereum, infundibulum, and optic commissure ; its anterior boundary by the anterior commissure and laminae cinerea ; its posterior boundary by the corpora quadrigemina and posterior commissure. The cavity of the ventricle is small, and it is crossed at its middle by the middle or soft commis- sure, whieb consists of grey matter and connects the two inner surfaces of the optici thalami together, K the anterior pillars of the fornix be separated, the anterior white commissure may be seen entering the lenticular nuclei. The white fibres of the posterior commissure pass across between the two optic thalami in front of the corpora quadrigemina. BASAL GANGLIA. § 678. The ganglia of the base of the cerebrum are the corpora striata, the optici thalami, the corpora geniculata, the corpora quadrigemina, and the locus niger, (1). The corpora striatum is situated in front and to the outer side of the optic thalami, and consists of two masses of grey matter, separated from each other by bands of medullated fibres, which pass from below upwards through its substance. The upper mass projects into the lateral ventricle, and is called the intra-ventricular portion or caudate nucleus. The caudate nucleus consists of a club-shaped portion directed forwards, and a slender tail-like extremity directed backwards, the two together forming almost a complete ring, which encircles the optic thalamils and internal capsule, like a loop or surcingle. The body of the nucleus grows ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 485 smaller as it extends backwards in the upper part of the ventricle, and soon runs into the tail-like prolongation ; when the latter reaches the posterior end of the optic thalamus it curves downwards into the inferior horn of the ventricle and runs forward to its anterior extremity, when it Fig. 204. Fig, 204 (From Henle's Anatoiuie'. Ccl*, Knee of the corpus callosum. Cs, Corpus striatum. Vsl, Ventricle of the septum lucidum. Cf , Crura of the fornix. Sf, Taenia semicircularis. Ts, Anterior tubercle of the optic tha- lamus. Basal Ganglia viewed from above. Com, Cop, The middle and posterior commissures respectively. Tfo, Taenia thalami opt. Pv, Pulvinar. Tho, Optic thalamus. Cn, Pineal gland. Pen, Peduncles of the pineal gland. 436 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. ^ terminates in an enlarged extremity almost exactly opposite the point where it started in the anterior horn. The head of the caudate nucleus is continuous with the lenticular nucleus and with the grey matter of the anterior perforated sjDace. The extremity of the surcingle, on the other hand, is connected with a deposit of grey matter forming the anterior wall of the inferior horn of the ventricle, named the amygdala. The tsenia semicircularis accompanies the concave border of the surcingle, and runs forwards along the roof of the inferior horn of the ventricle to its anterior end, and there terminates in the amygdala (Dalton). In a vertical transverse section of the brain through the optic thalamus the superior portion of the surcingle is visible above the lenticular nucleus and internal capsule, while the inferior portion appears as aa isolated mass of grey matter below the level of the lenticular nucleus and near the outer part of the inferior horn of the ventricle. Fig. 205. Fig. 205 (After Dalton). Longitudinal and Vertical Section of the Right Hemisphere, showing the Cavity of the Lateral Ventricle and the. Caudate Nucleus. — ii. Head of the caudate nucleus. S, Surcingle. V, Ventricle. A, Amygdala. 1, Parieto- occipital fissure. 2, Calcarine fissure. The lower extra-ventricular portion, or lenticular nucleus, is separated from the intra-ventricular part by a layer of white substance named the internal capsule, while it is separated from the Island of Reil by a layer of white substance named the external capsule, and a grey lamina termed the claustrum. The lenticular nucleus, as its name implies, is of the form of a bi-convex lens on horizontal section, but on a vertical section through its middle it appears triangular, the apex being directed inwards. Two white bands which run parallel to the outer surface of the nucleus or the external capsule divide it into three zones named from within outwards the first, second, and third divisions of the lenticular nucleus. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 437 (2) The optic thalamus is of an oval shape and rests on the crus cerebri of the same side. It is bounded externally by the corpus striatum and taenia sejnicircularis. The upper surface is free and is partly seen in the lateral ventricle, and is partly covered by the fornix, the former being called the anterior tubercle and the latter the posterior tubercle or pulvinar. Fig. 206. Sra Am Fig. 206 (From Henle's Anatomie). Vertical Section of the Brain immediately behind the Anterior Commissure of the Third Ventricle. — CcP, Corpus callosum ; Vsl, The fifth ventricle ; Ls, Lamina of the septum lucidum ; Cs, (Jaudate nucleus ; B', Internal capsule ; St, Taenia semicircularis ; Nl, Lenticular nucleus ; Cls, Claustrum ; In, Island of Eeil ; Cf, Interior pillars of the fornix ; Cp, External capsule ; Coa, Anterior commissure of the third ven- tricle ; Coa', Anterior commissure as it winds back beneath the lenticular nucleus to reach the convolutions of the cortex ; Am, Descending horn of the lateral ventricle ; Sra, Substantia retic. alba. ; II', Optic tract ; To, Tuber cLnereum. 4sB8 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The posterior surface is also free and projects into the descend- ing cornu of the lateral ventricle. The inner surfaces of the two thalami form the lateral walls of the third ventricle, and are connected together by a transverse portion which forms the middle or sofi commissure of the third ventricle. The inner surface is lined by grey matter which, according to Meynert, is distinct from that of the interior of the thalamus, and is pro- bably the upward continuation of the central grey substance of the spinal cord. The internal capsule consists of a thick band of medullated fibres, which separates the lenticular nucleus on the one hand from the caudate nucleus and optic thalamus on the other. On horizontal section the internal capsule is seen to consist of an anterior and posterior division, which form an obtuse angle with one another, the latter being called the knee of the internal capsule. The anterior division lies between the anterior and internal margin of the lenticular nucleus and the head of the caudate nucleus, and the posterior division between the posterior and internal margin of the lenticular nucleus and the optic thalamus ; while the knee of the capsule is directed inwards towards the third ventricle, and forms by its projection a partial separation between the caudate nucleus and optic thalamus. The external capsule consists, as already mentioned, of a thin band of white substance which bounds the lenticular nucleus externally and lies between it and the claustrum. (3) The corpora geniculata consist of two small oblong and flattened eminences connected with the posterior extremity of the optic tract, named respectively corpus geniculatum ex- ternum and internum. (4) The locus niger is a dark mass of grey matter which lies between the crust and tegmentum in the crus cerebri. It occupies nearly the whole diameter of the crus and extends from the anterior edge of the pons to the corpora albicantia. The pineal body or gland is a reddish body, enveloped by the velum interpositum, and situated upon the anterior eleva- tions of the corpora quadrigemina. The pedu7ides of thepitual body, by means of whicli it is connected with thereat of the cerebrum^ pass forwards,, one on the inner side of each optic ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 439 thalamus, to join, along with the tteuia aemicircularis, the anterior pillar of the fornix of its own side. (5) The corpora quadrigemi/na or optic lobes are situated behind and between the optici thalami, and rest upon the posterior surface of the crura cerebri These bodies are divided into four eminences by a longitudinal and transverse fissure, the anterior pair being named nates, and the posterior testes. From each testis a white cord, the superior peduncle of the cere- bellum, passes backwards to the cerebellum, while the valve of Vieussens, or anterior medullary velum, stretches between the pair of cerebellar peduncles. The aqueduct of Sylvius is a narrow canal which passes beneath the corpora quadrigemina, and connects the third with the fourth ventricle, [t is lined by a ciliated cylindrical epi- thelium, DISTEIBUTION OF THE ARTERIES OF THE BRAIN. § 679. The arteries of the brain are derived from two great trunks — the vertebral and internal carotid arteries. The branches of the vertebrals and of the basilar trunk formed by their union supply the posterior and lesser portion of the brain, while the terminal branches of the internal carotid arteries supply the anterior and greater part of the brain. The branches distri- buted to the brain from the vertebral arteries may be called the posterior or vertebral, and those derived from the internal carotids the anterior or carotid arterial system. The posterior cerebral arteries are the terminal branches of the basilar trunk. Each artery winds round the crus cerebri to reach the occipital lobe, and gives off a number of twigs — the posterior median group (Fig. 211, 2) — which pierce the pos- terior perforated space, and supply the internal surface of the optic thalamus, and the walls of the third ventricle. Branches. — A choroid branch is given off to the velum interpositum, and small twigs pass into the substance of the crus cerebri as the vessel winds round it. A number of small branches, the postero-lateral group (Fig. 211, 4), enter the base of the brain behind the posterior border of the crus cerebri, and pass into the optic thalamus and corpora quadrigemina. The cortical branches are three in number ; the first, or anterior tem- poral artery, being distributed to the anterior part of the uncinate gyrus 440 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. and its vicinity ; the second, or posterior temporal artery, to the posterior part of the uncinate gyrus and the lower part of the temporo-sphenoidal lobe ; and the third, or occipital artery, to the inner and outer surfaces of the occipital lobe. Fig. 207. Fig. 207 (After Ecker and Duret). View of the Brain from below. DISTRIBUTION OF VESSELS. The region bounded by the line ( ) represents the territory over which the Internal and Inferior Frontal Branches of the Anterior Cerebral Artery are distributed. The regions bounded by the line ( ) represent the territories over which the branches of the Posterior Cerebral Artery are distributed. I. Is the region of the Anterior Temporal Artery, II. ,, ,, Posterior Temporal Artery. III. ,, ,, Occipital Artery, The internal carotid artery reaches the base of the brain close to the outer side of the optic commissure, and immediately breaks up into two branches — the anterior and middle cerebral arteries. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 441 The anterior cerebral artery {Fig. 211, C A) runs forwards in the longitudinal fissure, and, turning round the corpus callosum, is distributed to the anterior part of the cerebrum. The arteries of the two sides are united at their commencement by a short transverse branch, the anterior coTiimunicating artery. Fig. 208. Fig. 208 (After Ecker and Duret). Inner Surface of Bight Hemisphere. DISTRIBUTION OF VESSELS. The regions bounded by the line ( ) represent the territories over which the branches of the Anterior Cerebral Artery are distributed. I. Is the territory of the Interior and Anterior Frontal Artery. II. ,, ,, Internal and Middle ,, ,, III. ,, ,, Internal and Posterior ,, ,, The regions bounded by the line ( ) represent the territories over which the branches of the Posterior Cerebral Artery are distributed. II. Is the territory of the Posterior Temporal Artery. III. ,, ,, Occipital Artery. Branches. — The anterior mediavt, group {Fig. 211, 1) are given off from the anterior communicating and the commencement of the anterior cere- bral arteries ; they supply the anterior part of the head of the caudate nucleus. The cortical branches are four in number — the first being dis- tributed to the two internal orbital convolutions ; the second to the ante- rior extremity of the marginal convolution, and to the superior and anterior portions of the middle frontal convolutions on the outer surface ; the 442 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION, third to the inner surface of the hemisphere as far as the extremity of the calloso-marginal fissure ; and the fourth to the quadrate lobule, the last supplying a branch to the corpus callosum. The middle cerebral or Sylvian artery (Figs. 210, 211, S) runs in the fissure of Sylvius, and is the largest and most important branch of the internal carotid artery. It gives small branches — the antero-lateral group {Fig. 211, 8) — which pierce the anterior perforated space, and supply the corpus striatum and anterior part of the optic thalamus. Fig. 209. Fig. 209 (After Ecker and Duret). Outer Surface of the Left Hemisphere. DISTRIBUTION OP VESSELS. The region bounded by the line ( ) represents the territory over which branches of the Anterior Cerebral Artery are distributed. The anterior regions bounded by the line ( ) represent the territories over which branches of the Middle Cerebral Artery are distributed. I. Is the region of the External and Inferior Frontal Artery. II, ,, ,, Anterior Parietal Artery. III. „ ,, Posterior Parietal Artery, IV. ,, ,, Parieto-sphenoidal Artery. The posterior and inferior region bounded by the line (— • — .-— ) represents the territory over which branches of the Posterior Cerebral Artery are distributed. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 443 Branches. — A choroid branch is given oflf either by the middle cerebral or internal carotid arteries, which winds round the crus cerebri to reach the choroid plexus of the lateral ventricle. The main trunk divides into four branches. The first, or inferior frontal branch (Fig. 210, 1), is limited Fig. 210. Fig. 210. Diagram Showing the Area of Distribution of the Middle Cerebral Artery. S, Sylvian or middle cerebral artery ; P, Perforating branches ; 1, Inferior frontal branch ; 2, Ascending frontal branch ; 3, Ascending parietal branch ; 4 and 5, Parieto-sphenoidal and sphenoidal branches; A, Ascending frontal convolution; 15, Ascending parietal convolution; Fj, Fj, F3, First, second, and third frontal convolutions; Pj, P2, P3, First, second, and third parietal convolutions; T,, T2, T3, First, second, and third temporo-sphenoidal con- volutions ; OL, Occipital lobe. in its distribution to the outer part of the orbital surface and the adjacent inferior or third frontal convolution. The second, or ascending frontal branch {Fig. 210, 2), supplies the posterior part of the middle frontal and the chief part of the ascending frontal convolutions. The third, or ascending parietal artery {Fig 210, 3), passes into the fissure of Rolando, and supplies the rest of the ascending frontal and the ascending parietal con- volutions as well as the anterior part of the superior parietal lobule. The fourth and fifth, or parieto-sphenoidal and sphenoidal branches {Fig. 210, 4 a,ud 5;, supply the inferior parietal lobule and the superior temporo- sphenoidal convolutions. The 'posterior communicating artery is a long and slender vessel which connects the internal carotid with the posterior cerebral arteries. 444 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. The circle of Willis is formed by the union of the anterior and posterior arterial cerebral systems by means of the posterior communicating arteries. The free anastomosis which is thus formed enables the circulation of blood in the brain to be carried on when one of the main trunks is obstructed. Fig. 211. Fig. 211 (After Charcot). Diagram of the Distribution of the Vessels at the base of the Cerebrum. — CA, Anterior cerebral artery. S, S, Sylvian arteries. V, V, Vertebral arteries. B, Basilar. CP, CP, Posterior cerebral arteries. 1, 2, 3, 3, 4, 4, G-roups of nutritive arteries. The line limits the ganglionic vascular area. The following parts of the encephalon are situated within this vascular area : the optic commissure, laminae cinerea, in- fundibulum and tuber cinereum, corpora albicantia, posterior perforated spot with part of the crura cerebri, and the origin of the third pair of nerves. Cortical System of Arteries. — The arteries which supply the cortex of the brain ramify in the pia mater and are distributed to the grey matter of the convolutions and subjacent white matter. The terminal ramifica- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 445 tions of the Sylvian artery may be taken as the type of the distribution of the cortical system of arteries. The main artery divides into the five secondary branches which have already been described, and each of these again subdivides into two or three tertiary branches. Each tertiary branch (Fig. 212, A) of the main artery subdivides into primary {Fkj. 212, B), and secondary twigs {Fig. 212, C, C), and these form in the pia mater a vascular ramification from which the nutritive arteries of the brain are derived. Duret asserts that the tertiary branches of the main artery sometimes anastomose with similar branches of the neighbouring vascular territories, but the primary and secondary twigs of these branches do not anastomose amongst themselves. Fig. 212. Fig. 212 (After Duret).— A, Tertiary branch of the main artery. B, Primary twigs. C, C, Secondary twigs. 2, 2, Cortical arteries. 3, Network of cortical arteries in the cerebral tissues. Nutritive Arteries of the Brain. The nutritive arteries are derived, not only from the extremities of the primary and secondary twigs, but a large number issue from the sides of these twigs, as well as from the sides of the tertiary branches of the main artery {Fig. 212, I, 2). The nutritive arteries are of two kinds — (a) the lotig or medullary, and (6) the short or cortical arteries. (a) The medullary arteries pass into the substance of the centrum ovale for a distance of three or four centimetres. They do not commu- nicate with each other in their course except by fine capillaries, and con- sequently constitute so many small independent vascular territories. The terminations of these vessels approach the upward continuation of the gang- 446 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. lionic system of vessels, but the two systems do not appear to anastomose with one another. In a section of a convolution, twelve or fifteen medul- lary arteries may appear ; three or four of these pass into the free surface of the convolution {Fig. 213, 1), and pursue a vertical course; those which enter the sides of the convolution pursue an oblique course through it, while those which pass into the bottom of the fissure again become vertical. Fia. 213. Fig. 213 (After Buret).—!, 1, Medullary arteries. 1', Group of medullary arteriea in the fissure between two neighbouring convolutions, 1", Arteries of the system of arcuate fibres. 2, 2, 2, Arteries of the grey substance of the cortex, a, A large meshed capillary network situated under the pia mater. 6, A smaller meshed capillary network situated in the tniddle layers of the cortex, c, Some- what larger network in the internal layers adjoining the white substance. d, Capillary network of the white substance. (6) The coHical nutritive arUnes arise from the vascular network of the pia mater in the same way as the long arteries, but the former are thinner than the latter and pursue a shorter course. Some of these vessels pass through the whole thickness of the grey substance, and give small capillaries to the centrum ovale, while others terminate in the sub- stance of the cortex. The Vascular network in the convolutions possesses the following characteristics : — In the .first layer, about one-half milli- metre in thickness, the meshes of the network aie large {Fig. 213, to) ; in ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 447 the second, correspondug to two layers of ganglionic cells, a very close and fine vascular network is formed {Fig. 213, b) ; iu the third, corre- sponding to the internal layers of the cortex, a larger and coarser vascular network exists {Fig. 213, c); and in the fourth layer, or medullary sub- stance, a still larger' and coarser vascular network is observed. The Central or Oanglionic System of Arteries. These arteries consist of small branches which are given off from the trunks of the chief cerebral vessels ; they pierce the base of the brain perpendicularly to reach the substance of the basal ganglia. These arteries form six main groups, which may be named the anterior and posterior median {Fig. 211, 1 and 2), the right and left antero-lateral (Fig. 211, 3, 3), and the right and left postero-lateral {Fig. 211, 4, 4) groups. An imaginary line passing round the circle of Willis, at a distance of two centimetres external to it, would completely surround all these vessels, and the area so limited may therefore be called the ganglionic vascular area (Charcot). All these vessels are terminal arteries. Some of these vessels are^ of sufficient importance, owing to their liability to rupture, as to deserve special description. The vessels derived from the middle cerebral artery — the antero-lateral group— after piercing the anterior perforated Fig. 214. Fig. 214 (From Buret). Transverse Section of the Cerebral hemispheres, about 1 cm. behind the Optic Commissure. Akteeies op the Corpus Striatum. — Gh, Chiasraa ; B, Section of the optic tract ; L, Lenticular nucleus ; /, Internal capsule ; C, Caudate nucleus ; JE, External capsule ; T, Claustrum ; R, Island of Reil ; V, V, Section of the lateral ventricle; P, -P, Anterior pillars of the fornix; 0, trrey substance of the third ventricle. Vascular Areas.— I, Anterior cerebral artery ; II, Middle cerebral artery ; III, Posterior cerebral artery. — 1, Internal carotid artery ; 2, Sylvian artery ; 3, Anterior cerebral artery ; 4, 4, External arteries of the corpiis striatum (lenticulo-striate artery) ; 5, 5, Internal arteries of the corpus striatum (lenticular arteries). The opto-striate artery is not represented in the figure. 448 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. space, ascend vertically to supply the corpus striatum, the internal capsule, and a portion of the optic thalamus. The following branches may be distinguished : — (a) Lenticular branches consist of two or three small twigs, which ascend vertically and enter the substance of the lenticular nucleus, and are distributed to its two inner divisions and the adjoining portion of the caudate nucleus {Fig. 214, 5). (h) The lenticulo-striate branch is much larger than either of the pre- ceding arteries. It ascends along the external surface of the outer division of the lenticular nucleus, traverses the superior part of the internal cap- sule, and then passes from behind forwards into the substance of the caudate nucleus. It gives branches to the outer division of the lenticular nucleus, the internal capsules, and the caudate nucleus {Fig. 214, 4). {c) The lenticulo-optic branch passes, like the lenticulo-striate artery, along the external surface of the outer division of the internal capsule, passes through the posterior part of the internal ■ capsule, and terminates in the anterior and external part of the optic thalamus. The anterior median group of vessels derived from the anterior cerebral and anterior communicating arteries are small arteries ; they supply the anterior part of the caudate nucleus, and derive their chief importance from the fact that hsemorrhage from themmay rupture into the ventricles and thus cause rapid death. The posterior cerebral artery gives rise to two branches, which deserve special mention, (i.) HhQ posterior internal artery of the optic thalamus, which is derived from the artery near its point of origin from the basilar, and is distributed to the internal surface of the optic thalamus. Hsemor- rhage from this vessel often finds its way into the ventricular cavity, (ii.) The posterior external artery of the optic thalamus is derived from the posterior cerebral artery after it has wound round the peduncle. It passes upwards in the crus to the posterior part of the optic thalamus, where it terminates. It supplies the external geniculate bodies. INTERNAL STRUCTURE OF THE CEREBRUM. § 680. The cerebrum is made up of (1) grey and (2) white matter. (1) The ^re^/ mazier is disposed in three great groups : (a) the grey matter which forms the central end of the cerebro-spinal tube ; (6) the grey matter of the basal ganglia ; (c) the grey matter of the cortex of the hemisphere. {a) The grey matter which forms the central end of the cerebro-spinal tube has already been described up to the level of the opening of the aqueduct of Sylvius into the third ven- tricle, and the grey matter which surrounds the third ventricle ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. 449 may be regarded as the upward continuation of the central tube. The grey matter of the third ventricle consists of a well-defined layer covering the inner wall of each optic thalamus and the masses situated at the base of the brain between and in front of the crura cerebri ; viz., the posterior perforated space (pons Tarinij, tuber einereum, lamina cinerea, infundibulum, and part of the pituitary body, (6) The basal ganglia consist of the locus niger, red nucleus of the tegmentum, corpora quadrigemina, the corpora genicu- lata, the optic thalami, and corpora striata. The locus niger lies between the crus and tegmentum, and extends the whole diameter of the crus, and from the anterior edge of the pons to the corpora albicantia. It consists of nerve cells of various forms containing much dark pigment. The red nucleus of the tegmentum is a round, reddish-grey centre, in structure somewhat similar to the olivary body of the medulla oblongata. The corpora quadrigemina consist of grey and white matter, the former being continuous in front with the grey matter of the optic thalamus, and behind with that of the pons, and by means of the nucleus of the roof of the fourth ventricle with the corpus dentatum of the cerebellum. The Corpora Oeniculata. — The external geniculate body is densely filled with large branching and fusiform cells, and the fibres of the outer portion of the optic tract pass through it. The internal geniculate body contains numerous small nerve cells similar to those of the corpora quadrigemina. The optic thalamus is composed of interlacing fibres mingled with grey matter. The nerve cells in the grey matter are both multipolar and fusiform. The m,iddle or grey commissure, connecting the two thalami, consists of small cells containing yellow pigment. The corpus striatum is arranged in two chief masses, named respectively the caudate and lenticular nuclei. The caudate nucleus is connected below with the lamina cinerea, the anterior perforated space, and that part of the grey matter of the optic thalamus which is seen in the third ventricle. It contains large and small nerve cells, both possessing many branched processes. DD 450 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. No axis-cylinder process has been observed springing from the cells of the caudate nucleus. The lenticular nucleus is continuous below with the caudate nucleus, and with the grey matter of the anterior perforated space. The two innermost zones contain numerous large branching nerve cells with yellow pigment. The cells are smaller in the outer division of the nucleus. The claustrwm is made up of fusiform and bipolar cells, somewhat resembling the cells of the vesicular column of Clarke on the one hand, and those of the fifth layer of the cortex on the other. The amygdaloid nucleus is a small, round mass of grey matter, connected with the inferior part of the claustrum. It lies in front of the anterior extremity of the descending horn of the lateral ventricle, and is composed of fusiform cells similar to those of the claustrum. (c) The Grey Matter of the Cortex. — When a convolution is divided vertically the grey matter is seen to be confined to the surface and to enclose a white core. The cortical substance consists of cells and fibres embedded in a matrix similar to the neuroglia of the spinal cord. The cells are of various forms, the most usual forms being spherical, stellate, pyramidal, and fusiform. The fibres radiate into the grey cortex from the white centre of each convolution, their course being vertical to the free surface of the convolution. They are arranged in bundles as they pass through the grey substance, and this gives to the nerve cells a columnar arrange- ment. The radiating fibres are wanting in the sulci between the convolutions, but the internal layer of the grey substance of the cortex generally contains fibres which pursue an arciform course and connect adjacent convolutions. Fibres pass in all directions through the grey substance connecting its several layers, and forming a dense network, like that of Gerlach in the spinal cord. Layers of the Cortex. — The cortex of the cerebrum is divided into several layers, each of which possesses a definite histological character. The most commonly distributed form of structure is what Meynert has called the "five laminated type." The external layer consists of neuroglia and a layer of delicate ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 451 nerve tubes, along with a few scattered small nerve cells which are destitute of pro- cesses. The next layer is com- posed of small angular or pyramidal nerve cells with branching processes. The third layer contains large and small pyramidal cells with branching processes, arranged with their pointed extremi- ties towards the surface of the convolutions, and sepa- rated into groups by bundles of the radiating fibres. In the innermost portion of this layer the pyramidal cells are larger than in the remaining portions, and it has therefore been de- scribed as a separate layer by Dr. Lockhart Clarke. In the cortex of the occipital lobe the deeper cells of the third layer are pyramidal in form, with their bases turned inwards towards the medullary sub- stance, but their basal pro- cesses are directed laterally so as to connect adjacent cells, and none of them appear to be directed inwards to connect the cells with the fibres of the medullary substance. In the anterior portion of the frontal convolutions the disposition of these cells is somewhat similar, but a distinct basal process has occasionally been observed, which is directed towards the Fig. 215. mm liijiidiiig Fig. 215 (After Meynert). Transparent Section of a Furroiv of the Third Cere- bral Convolution of Man. Magnified 100 decimeters. — 1, Layer of the scat- tered small cortical corpuscles ; 2, Layer of close-set, small pyramidal corpuscles ; 3, Layer of large pyra- midal cortical corpuscles (formation of the comu Ammonis) ; 4, Layer of small, close-set, irregular-shaped cor- tical corpuscles (granule -like forma- tion) ; 5, Layer of fusiform cortical corpuscles (claustral formation) ; m, the medullary lamina. 452 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. medullary substance of the convolution, and which afterwards becomes continuous with one of the fibres of the centrum ovale. In the central convolutions of the brain Betz and Mezier- jewski have discovered cells which are two or three times the size of the pyramidal cells of the other regions of the cortex, and they have consequently named them giant-cells. In Fig. 216. Fig. 216. Pyramidal Giant-Cell. — n. Nucleus ; a, a, a. Branched processes ; c, Unbranched basal process. addition to the branched protoplasmic processes {Fig. 216, a, a) which connect neighbouring cells with one another, these cells possess a distinct axis-cylinder process {Fig. 216, c). The latter is always unbranched, and after becoming surrounded by a medullary sheath it forms the axis cylinder of a nerve fibre of the centrum ovale. Giant-cells have been observed in the para- central lobule and in a portion of the postero-parietal, as well as in the ascending frontal and parietal convolutions, and posterior extremities of the three frontal gyri. These cells are disposed ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 453 in groups, and correspond in position to the motor centres of physiologists. The giant-cells vary greatly in size, the largest being found, as we have already seen, in the paracentral lobule, which may be regarded as the upper extremity of the ascending frontal and parietal convolutions. Large pyramidal cells are also found in the upper part of the ascending frontal convolu- tions, but Dr. Bevan Lewis has found that they diminish in size from the upper extremity until at the lower extremity they are but half the size. The pyramidal cells of the posterior extremities of the frontal convolutions are on the whole smaller than those of the ascending frontal, and the cells also diminish from above downwards, those in Broca's convolution being the smallest. The fourth layer consists of closely-set angular corpuscles with fine processes, placed irregularly and not distinctly sepa- rated into groups. The fifth layer consists of medium-sized, fusiform, and bipolar cells. The long diameters of these cells run parallel to the layers of the cortex, and are associated with the system of fibres which connects different convolutions of the same hemisphere with one another. (2) The white matter of the cerebrum consists of (a) trans- verse or commissural fibres ; (6) longitudinal or collateral fibres ; and (c) ascending or peduncular fibres. (a) The transverse or commissural fibres consist of the following : — (i.) The transverse Jibres of the corpus ccdlosum pass transversely from one side to the other, and connect corresponding convolutions in the hemispheres. These fibres lie on a plane superior to those of the corona radiata, and consequently the two systems of fibres interlace on their way to the convolutions. (ii.) The Jibres of the anterior commissure wind backwards through the lenticular nuclei to reach the convolutions around the Sylvian fissure. (iii.) The fibres of the posterior commissure run through the optic thalami. (6) The longitudinal ox collateral By^iQm. of fibres are the following : — (i.) Arcuate fibres or fibrce proprice, which are situated immediately beneath the inner surface of the cortex, and connect together the grey matter of adjacent convolutions. 454) ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. (ii.) Fibres of the gyrus forniccttus take a longitudinal course imme- diately above the corpus callosum and form the white matter of that convolution. In front they bend round the corpus callosum, and become connected with the anterior perforated space. Behind they turn round the back of the same body, and are said to pass forwards to reach the anterior perforated space, so that these fibres completely surround the corpus callosum. OflFsets from these fibres pass upwards and backwards to reach the summits of the secondary convolutions derived from the gyrus fornicatus near the longitudinal fissure, (iii.) Longitudinal septal fibres lie on the inner surface of the septum lucidum and extend into the gyrus fornicatus. (iv.) Th.Q fasciculus unoinatus passes across the bottom of the Sylvian fissure, and connects the convolutions of the frontal and temporo- sphenoidal lobes. (v.) The longitudinal inferior fasciculus connects the convolutions of the occipital with those of the temporal lobe. (vi.) The longitudinal fibres of the corpus callosum (nerves of Lancisi) connects the anterior and posterior ends of the callosal convolution. (c) The Ascending or Peduncular Fibres. — The fibres which connect the central grey tube with the encephalon have already been traced as far as the crura. The upward continuation of the fibres of the anterior root-zones of the cord terminate in the optic thalamus. The posterior longitudinal fasciculus lies in front of the nucleus of origin of the third nerve, and when the aqueduct of Sylvius opens into the third ventricle, the fibres of the fasciculus bend outwards in the posterior commis- sure of the third ventricle to reach the inner wall of the optic thalamus, where they appear to terminate. Meynert describes these fibres as passing downwards and outwards to form part of the fillet of the crus cerebri, but examination of the crus in the embryo does not bear out this statement. The fibres of the posterior longitudinal fasciculus are meduUated at an early period of embryonic life, but in a nine months embryo no medullated fibres having the course described by Meynert can be seen in the crus cerebri. The fibres of the posterior com- missure, on the other hand, are the first fibres of the cerebrum to assume a medulla (Flechsig). The upward continuation of the external portion of the anterior root-zone of the cord lies in the crus cerebri to the outside of the third nerve and poste- rior longitudinal fasciculus, and the fibres of this area are con- tinued upwards into the optic thalamus, where they form a thin ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 455 stratum of fibres which separates the grey matter which lines the third ventricle from the rest of the optic thalamus. A portion of the upward continuation of the external part of the anterior root-zone of the cord bends backwards in the pons to reach the corpora quadrigemina. Fig. 217. Fqs ^'^^ Fig. 217 (From Henle's Anatomie). Vertical Section of the Brain parallel to the course of the Ascending Fibres of the Right Cerebral Peduncle. — *, Great longi- tudinal fissure ; 1, Left ; and 2, Eight hemisphere ; Lq, Lamiria quadJi- femina ; Cn, Pineal Gland ; CcP, Corpus callosum ; Tho, Thalamus : Sz, triatum zonale of the thalamus ; Cs, Caudate nucleus ; Ni, Lenticular nucleus ; Tbo, Tuber olfactorium ; Cls, Claustrum ; Sn, Locus niger ; Ntg, Red nucleus of the tegmentum ; Fqs and Fqi, Superior and inferior transverse fibres of the pons ; II', Optic tract. The corpora quadrigemina are connected with the optic tbalami by nervous tracts, named hrachia. The cerebellum is connected with the corpora quadrigemina by the superior peduncles. A large number of the fibres of the superior peduncles of the cerebellum decussate in the tegmentum, so that the fibres of the one side cross to become connected with the red nucleus of the opposite side. Some of these fibres 456 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. probably terminate in this nucleus, while others appear to pursue an uninterrupted course to the brain. The course of the fibres of the superior peduncles of the cerebellum is not well ascertained beyond the red nucleus. Some anatomists think that these fibres terminate in the optic thalamus, while others believe that they pass uninterruptedly as a thin stratum of fibres between the optic thalamus and the internal capsule, and through the corona radiata to reach the grey matter of the central convoluti&ns. Fig. 218. Fig. 218 (From Henle's Anatomic). Horizontal Section of the Hemisphere of the Brain, close to its Inferior Surface. — Lq, Lamina quadrigemina ; A, Aqueduct of Sylvius ; Ntg, Red nucleus of the tegmentum ; Rdf, and Raf, Descending and ascending roots of the fornix ; Co, Optic commissure, seen through the floor of the third ventricle ; Cs, Caudate nucleus of the corpus striatum ; Nl, The lenticular nucleus ; *, Division between the two nuclei of the corpus striatum ; Spa, Anterior perforated space ; In, Island of Reil ; Coa', Anterior commissure ; Sn, Substantia nigra ; B', Transverse section of the crusta ; II', Optic tracts ; Cgl, External geniculate body. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 457 The Internal Capsule and Corona Radiata. — The crust of the cerebral peduncle consists of bundles of longitudinal fibres which have ascended mainly from the anterior pyramid of the medulla. The crust of the peduncle is, however, much larger Fig. 219. Fig. 219 (From Henle's Anatomie). Transverse Section of the Hemisphere of the Brain, at a little higher elevation than Fig. 218.— Cp, External capsule ; Cls, Claustrum. The remaining letters indicate the same as Fig. 218, 458 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. than the anterior pyramid, hence the fibres of the latter must have been reinforced in their ascent through the pons. The crust of the peduDcle is quadrilateral in form, but in as- cending to the hemispheres it becomes flattened from above downwards, and from within outwards, and the fibres spread out like a fan, the edges of which are directed forwards and Fig. 220. Fig. 220 (From Flechsig). Horizontal Section of the Brain of a Child nine months of age, the right side being at a someiohat lower level than the left half. — F, Frontal, T8, Temporo-sphenoidal, and O, Occipital lobes; Op, Operculum; In, Island of Keil ; Cls, Claustrum ; /'", Third frontal convolution ; Th, Optic thalamus ; NC, Caudate nucleus ; NG', Tail of caudate nucleus ; LN, Lenticular nucleus ; I, II, III, First, second, and third divisions of the lenticular nucleus ; EK, External capsule ; IK, Posterior division, IE', Anterior division, and K, Knee of the internal capsule ; ah, ph. Anterior and posterior horns respectively of the lateral ventricles ; gcc. Knee of the corpus caUosum ; sp, Splenium ; mc, Middle commissure ; /, Fornix; si!. Septum lucidum ; a, Cornu Ammonis. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 459 backwards. The fan formed by these fibres is bent into the form of an incomplete hollow cone, having its concave surface directed downwards and outwards, and its convex upwards and inwards. As the fibres ascend they pass at first between the optic thalamus and lenticular nucleus, but higher up they pursue their course beneath and to the outside of the thalamus and caudate nucleus, and over the lenticular nucleus. On horizontal section of the hemisphere, close to the inferior surface of the brain, the crusta is seen to be of an irregularly quadrilateral form, with its long axis directed from before backwards and from within outwards {Fig. 218, B'). At a higher level the crust, or what may now be regarded as the internal capsule, is of the same general form as in the preceding section, but its long axis is somewhat lengthened in proportion to its short axis (Fig. 219, B'). Still higher up the internal capsule has spread out from before backwards, while the anterior half forms an obtuse angle with the posterior. The angle where the halves meet is called the hnee {Fig. 220, .ST), while the divisions themselves ai'B called the anterior {Fig. 220, IK') and posterior segments {Fig. 220, IK) of the internal capsule. Corona Radiata. — On emerging from the basal ganglia the fibres of the internal capsule radiate in a,ll directions to reach the cortex of the hemisphere, hence these have been described by Reil under the name of corona radiata, and the point at which the fibres emerge from between the ganglia is called the foot of the corona radiata. The following fibres may be distinguished in the crusta and internal capsule: — (1) The sensory peduncular tract and optic radiations of Gratiolet, the latter joining the internal capsule from the optic thalamus; (2) the pyramidal tract ; (3) fibres in the crust connecting the central grey tube and the corpus striatum ; (4) fibres issuing from the external surface of the optic thalamus to join the internal capsule ; (5) fibres issuing from the external surface of the caudate nucleus ; (6) fibres ascending from the superior and internal surface of the lenticular nucleus ; (7) fibres already described ascending from the superior peduncle of the cerebellum ; (8) fibres from the corpus callosum (Wernicke). (1) Sensor?/ peduncular fibres and optic radiations of Gratiolet. — The posterior root-zones and columns of GoU terminate, as we have already seen, in the triangular and clavate nuclei ; and the connection between 460 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. these nuclei and the olivary body, and of the latter with the cerebellum, has already been sufficiently described. It has also been seen that the sensory fibres cross in the spinal cord, but Meynert describes a sensory crossing which takes place in the lower part of the medulla oblongata. According to this author, fibres issue from the nuclei of the cuneate and slender fasciculi which pursue an arcuate course round the central grey column, and become mixed with the fibres of the lateral column as they bend forwards to decussate. As already noticed, Flechsig thinks that these fibres curve round the olivary body of the same side, and enter its substance, while Meynert thinks that they form the outer fasciculus of the anterior pyramid of the medulla oblongata, and ascend with the latter up through the pons to reach the crus cerebri. Debove and Gombault describe an additional crossing of sensory fibres higher up in the medulla. These fibres pursue an arcuate course from the triangular and clavate nuclei, pass forwards to the outside of the olivary body, and then become subdivided into small Pig. 221 (From Henle's Anatomie). Transverse and Oblique Section of the Basal Ganglia slanting upwards and forwards from the anterior edge of the Pons (P). — B, Crust of the crus cerebri; B', Radiation of the peduncular fibres into the hemisphere ; Sn, Locus niger ; Ntg, Red nucleus of the tegmentum ; *, Upper portion of the formatio reticularis; Tho, Thalamus opticus; Cs, Caudate nucleus; II', Optic tract; Hp, Hippocampus. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 461 fasciculi, which penetrate into the posterior and external aspects of the anterior pyramid, and finally curve upwards, becoming mixed with the motor fibres. It is very probable that these sensory fibres occupy the posterior and external portion of the pyramidal tract in its ascent through the pons, inasmuch as bundles of fibres exist here which are not so dis- tinctly medullated in a nine months human embryo as those lying in o ^i rsA- Fia. 222 (Ait«r Debove and Gombault) -Section of the Anterior Pyramid (P) of the Medulla Oblongata, on a level with the middle part of the crossing of the Sensory Fibres.— F^, Sensory fibres; FSA, Posterior and external sensory fasciculus which does not penetrate into the substance of the pyramid ; E, Crossing of the sensory fibres ; O, Nucleus of the pyramid; Z, Stratum zonale. front of them. It has been at least ascertained that the sensory fibres occupy the external fourth of the crusta, and about the posterior third of the posterior segment of the internal capsule in their ascent towards the cortex of the brain. These fibres do not appear to be in any way con- nected with the optic thalamus and lenticular nucleus, but pass onwards between them to reach the cortex of the brain. In the posterior third of the posterior segment of the internal capsule the sensory fibres bend abruptly backwards, and then radiate to reach the convolutions of the occipital and tempore- sphenoidal lobes. The fibres of this tract are never medullated in an embryo of nine months, and can be readily traced upwards in the outer segment of the crusta and posterior segment of the internal capsule. In addition to the fibres which ascend from the spinal cord, medulla oblongata, and pons, the sensory tract in the internal capsule contains fibres which connect the first and second cerebral nerves with the cortex of the brain. The optic tracts take origin in the basal ganglia by an internal, middle, and external root. The internal root consists of a bundle of fibres which passes between the external geniculate body and outer edge of the crusta, and penetrates into the substance of the internal geniculate body, appearing to end in the anterior pair of corpora quadrigemina. Huguemin has recently main- 462 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. tained that this root is connected with the posterior pair of corpora quadrigemina, either directly or through the medium of the external geniculate body. The middle root terminates in the external geniculate body. The extenml root passes to the outside of the external geniculate body and penetrates the inferior peduncle of the optic thalamus about ] 2mm. in front of the posterior border of the pulvinar. By extirpating the eyeballs of young hares Gudden found that, when the animals were killed some months subsequently, the anterior pair of corpora quadrigemina, the optic thalami, and the external geniculate bodies were atrophied; while the posterior pair of corpora quadrigemina and the internal geniculate bodies were unaffected. In man, however, both the anterior and posterior pair of corpora quadrigemina have been found diminished in size in cases of long standing atrophy of the optic nerves. These various roots of the optic nerves appear to be connected with the cortex of the brain by means of the fibres which have been named the optic radiations of Gratiolet. This bundle of fibres issues from the posterior and external border of the optic thalamus and is closely applied to the peduncular sensory tract in its passage through the internal cap- sule ; these fibres radiate backwards and upwards to be connected with the convolutions of the occipital lobe. The olfactory lobe, according to Meynert, divides in front of the anterior perforated space into an internal and external olfactory convolution. The external convolution coalesces with the temporal extremity of the gyrus fornicatus or the subiculum cornu ammonis. The internal convolution is continuous with the frontal end of the gyrus fornicatus, beneath which it may be recognised for some distance as a distinct longitudinal elevation. A considerable portion of the white substance of the olfactory lobe traverses the corpus striatum until it meets the anterior commissure coming in the opposite direction. The olfactory fibres are supposed to cross in the anterior commissure, corresponding to the crossing of the fibres of the optic nerves in the chiasma. After crossing these fibres appear to ascend upwards and backwards and to join the fibres of the optic radiations of Gratiolet, and pass along with them to the convolutions of the cortex of the occipital or temporo-sphenoidal lobe. The posterior third of the posterior segment of the internal capsule, therefore, contains the peduncular sensory fibres and the fibres which connect the optic nerves, and the olfac- tory bulb with the cortex of the brain. (2) The Pyramidal Tract. — The course of the fibres of the pyramidal tract has already been traced upwards through the spinal cord, medulla oblongata, and pons. It remains to trace the course of these fibres through the crusta, internal capsule, and corona radiata to their destination in the convolutions of the cortex. We have also found that the greater number of the fibres of the pyramidal tract in the cord are meduUated in a nine months human embryo, while a large proportion of the fibres which join the tract in the medulla oblongata and pons are non-medullated. The ex- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 4G3 fcernal portion of the anterior pyranaids of the medulla contains on the cue hand meduUated without any admixture of non-medullated fibres, the internal and anterior margin of the pyramid on the other hand contains non-medullated without any admixture of meduUated fibres, while an area lies between these in which the two kinds of fibres are mixed. The first Fig. 223. ^ i arr Fig. 223 (Modified fron I , / -se Section of the Cms Cerebri on a level with the anterior pair of Corpora Quadrigemina, from a nine months embryo. — cc, crusta ; P, fundamental, P', mixed, and p, accessory portion of the pyra- midal tract ; LN, locus niger ; RN, red nucleus of the tegmentum ; i, posterior longitudinal fasciculus ; ar and ar', upward continuation of the internal and ex- ternal portions respectively of the anterior root-zone of the spinal cord ; iii, third nerve ; iii', nucleus of the third nerve ; iv, fourth nerve ; iv', nucleus of the fourth nerve ; iv", crossing of the fibres of the fourth nerves to opposite sides ; dt, descending root of the trigeminus ; cc, aqueduct of Sylvius ; x, cross- ing of the fibres of the superior peduncles of the cerebellum ; pf, fasciculus of meduUated fibres proceeding to the anterior pair of corpora quadrigemina. of these regions may be called the fundamental, the second the accessory, and the third the mixed area. We have already seen that in the pons the accessory portion of the pyramidal tract lies internal to the fundamental portion, and in the crusta they occupy the same relative positions. The fundamental portion of the tract occupies the greater portion of the middle 464 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. third {Fig. 223, P), and the accessory portion the larger part of the internal third of the crusta {Fig. 223, p). The mixed area of the tract lies partly in the middle third of the crusta between the fundamental area and the locus niger, and winds round to the inside of the fundamental and between it and the accessory area {Fig. 223, P'). Speaking broadly, the fundamental fibres ascend in the middle {Fig. 224, P) and the mixed fibres in the anterior thii-d of the posterior segment of the internal capsule {Fig. 224, P'), while the accessory fibres ascend in the anterior segment of the capsule {Fig. 224, p). Fig. 224. Fig. 224, Horizontal Section of the Basal Ganglia and Internal Capsule of a Nine Months Embryo, — LN, Lenticular nucleus ; II, III, Second and third segments of the nucleus respectively ; NC, Caudate nucleus ; Th, Optic thalamus ; In, Island of Keil ; ps, Peduncular sensory tract and optic radiations of Gratiolet ; P, Fundamental, P', Mixed, and p, Accessory portion of pyramidal tract ; C, Fibres from the corpus callosum (?). The fibres of the pyramidal tract, on emerging from between the basal ganglia, ascend in the corona radiata, and are distributed to the convo- lutions of the cortex in the following manner : — The fundamental fibres pass to the central convolutions near the margin of the great longitu- dinal fissure. These convolutions are, briefly, the parietal lobule, the paracentral lobule, the superior extremities of the ascending frontal and parietal convolutions, and probably also the posterior extremity of the first frontal convolution. These convolutions are, as we have already seen, those in which the largest pyramidal cells of the fourth layer of ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 465 the cortex have been found. The accessory fibres are distributed to the convolutions that constitute the operculum. These convolutions are the posterior extremity of the third frontal and the inferior extremities of the ascending frontal and parietal convolutions, and correspond to those in which the smaller-sized pyramidal cells with axis-cylinder processes have been observed. The mixed pyramidal tract is distributed to the convolutions between the two other areas. These convolutions are the posterior extremity of the second frontal and the middle of the ascending and parietal convolutions. What connection exists between the pyramidal tract and the supra-marginal and angular gyri has not been ascertained. (3) Fibres comiecting the Central Grey Tube with the Corpus Striatum.. — The first and second divisions of the lenticular nucleus are connected with the crusta by a band of radiating fibres, which in their ascent are disposed in two thin bands, named the strice medullarea, and which run parallel to Fig. 225. Cs ^^. Tlo „--— Oom. / / Fig. 225 (From Henle's Anatomie). Transverse and Vertical Section of the Basal Ganglia on a level with the Corpora Caudicantia. Cca, Corpora albicantia. Nl, Lenticular nucleus . Rdf, Descending roots of the fornix. Cst, Corpus subthalamicum. Com, Anterior commissure. H', Optic tracts. Tto, Taenia of the optic thalamus. B, Crust of the cerebral peduncle. Cs, Caudate nucleus. EE 466 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. the outer surface of the nucleus, and divide it into three zones. Many of these fibres terminate in the substance of the nucleus, while others pass through it probably without interruption. A large number of these fibres at least pass transversely through the internal capsule, interlacing with its ascending fibres, and becoming connected with the optic thalamus and caudate nucleus. Fibres appear to enter the crusta from the locus niger, and it is not improbable that the latter nucleus is to be regarded as the means of communication between the anterior root-zone of the spinal cord and the corpus striatum. (4) Fibres issuing from the Exteriwd Surface of the Optic Tkalamtis to join the Internal Capsule. — The optic radiations of Gratiolet already described belong to this system of fibres, inasmuch as they issue from the external surface of the posterior portion of the thalamus. Other fibres issue from the external surface of the anterior two-thirds of the thalamus and join those of the pyramidal tract on their way to the cortex. The anterior radiating fibres of the thalamus are probably distri- buted to the convolutions of the frontal lobe, and the central radiating fibres to the convolutions of the parietal lobe, while as we have already seen the posterior radiating fibres are distributed to the convolutions of the occipital lobe. (5) Fibres issuing from the External Surface of the Caudate Nucleus. — These fibres are described as issuing from the external surface of the caudate nucleus, and as passing into the corona radiata immediately above and internal to the radiating fibres of the optic thalamus. (6) Fibres issuing from the Superior and Internal Surface of the Lenticular Nucleus to join the Ascending Fibres of the Internal Capsule. — A large num- ber of fibres issue from the superior and internal surface of the lenticular nucleus, and pass transversely through the internal capsule, interlacing with its longitudinal fibres. Other fibres are described as pursuing an ascending course parallel with the longitudinal fibres of the internal cap- sule. The latter fibres are supposed to radiate in all directions on gaining the corona radiata to become connected with the cortex. It is right, however, to add that the latest anatomical researches throw considerable doubts upon the existence of the radiating fibres which anatomists have described as connecting the caudate nuclei and the third division of the lenticular nucleus with the cortex. Wernicke states that neither the caudate nucleus nor the third division of the lenticular nucleus are directly connected with the cortex by radiating fibres, and he thinks that they must be regarded as independent ganglia, like the grey matter of the cortex itself. The first and second divisions of the lenticular nucleus form ganglia of interruption, which connect the caudate nucleus and the third division of the lenticular nucleus with the central grey tube. (7) Fibres Ascending from, the Superior Peduncle of the Cerebellum. — The red nucleus of the tegmentum is connected, as already described, with the fibres ascending in the superior peduncle of the cerebellum of the opposite side. Fibres appear to ascend from the red nucleus to the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 467 optic thalamus, and Flechsig supposes that some of the fibres of the superior peduncle of the cerebellam of the opposite side pass uninter- ruptedly through the red nucleus and along the internal surface of the fibres of the pyramidal tract to be distributed to the central convolu- tions of the cerebrum. (8) Fibres issuing from the Corpus Callosum and Descending into the Internal Capsule. — Wernicke states that the fibres of the corpus callosum which form the anterior wall of the anterior horn of the lateral ventricle wind backwards along the external border of the caudate nucleus, where they become mixed with the longitudinal fibres of the internal capsule He is unable to trace them further. (9) Fibres of tlie External Capsule. — The fibres of the external capsule either ascend from the crusta, pass along the inferior surface of the lenticular nucleus, and bend abruptly upwards round its inferior external angle to reach the external surface, or they take origin in the cells of the nucleus, and after issuing from its inferior surface pursue the course just described. These fibres ascend along the external surface of the lenticular nucleus forming the thin stratum of white matter between it and the claus- trum {Fig. 220, EK), and on reaching the corona radiata they radiate to reach the convolutions of the cortex. The external surface of the lenticular nucleus and the external capsule are simply in contact with one another, and there appear to be no connections formed between the fibres of the one and the cells of the other. The two surfaces are, indeed, separated in some places by blood-vessels ascending from the middle cerebral artery. Besides those of the internal capsule and corona radiata, other fibres connect the basal ganglia and the cortex of the brain. These fibres consist of the fornix, tcenia semicircular is, peduncwlus septi, and a considerable proportion of the fibres which constitute the collar or fillet of the crus. The fornix arises in the optic thalamus. Its fibres of origin are connected with the tcenia semicircularis and the peduncles of the pineal gland. They descend to the under surface of each thalamus, and after forming a loop in the corpora albicantia they ascend upwards and forwards in the walls of the third ventricle as the anterior pillars of the fornix. The fibres of each crus then pass backwards in the body of the fornix, and end as the taenia hippocampi in the gyrus of the same name. The tcenia semicircularis connects the apex of the temporal lobe with the whole length of the internal margin of the caudate nucleus. The fibres which penetrate into the anterior region of the head of that nucleus are named strice eorneoe. The pedunculus septi connects the cortical substance of the septum lucidum with the basal mass of the corpus striatum. The Collar or Fillet of the Crus Cerebri. — A bundle of fibres forms at the 468 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. posterior, inferior, and external angle of the optic thalamus, which winds downwards, outwards, and forwards round the posterior margin of the ascending fibres of the crusta. These fibres are named the inferior peduncle of the optic thalamus, and constitute the posterior portion of the collar or fillet of the crus ; they spread out on the roof of the descending cornu of the lateral ventricle and pass forwards to the convolutions of the anterior extremity of the temporo-sphenoidal lobe. It is probable that some of them also radiate backwards to reach the convolutions on the inferior surface of the occipital lobe. Other fibres appear to issue from the anterior, inferior, and external angle of the thalamus, which wind round the anterior border of the crusta, and terminate in the lenticular nucleus, or pass to the convolutions of the temporo-sphenoidal lobe. These fibres form the anterior portion of the collar of the crus. § 681. Development of the Brain. — The cerebral end of the cerebro- spinal tube is at first uniform in appearance with the spinal part, but it soon expands into three vesicular dilatations — the primary cerebral vesicles. These vesicles are named, from their relative positions, anterior, middle, and posterior, and the structures which go to form the several sub- divisions of the encephalon are produced in their walls. l!:\i% posterior cerebral vesicle first bends forwards to form the medulla oblongata, and then backwards to form the cerebellum, the pons being developed at the angle where these two parts are continuous with one another. The cerebellum consists at first of a central lobe, and the lateral lobes are only developed in the mammalia. The middle cerebral vesicle bends forwards from the posterior one, its central hollow becoming the aqueduct of Sylvius ; the optic lobes are formed in its roof, and the cricra cerebri in its floor. The antei'ior cerebral vesicle bends downwards from the middle vesicle, and its central hollow becomes the third ventricle. The optic thalami form in its lateral walls, and the pineal body in its upper and posterior wall. The lamina cinerea closes the vesicle in front. The posterior part of the anterior vesicle gives off" from each side a flask-shaped prolongation— the primary optic vesicle — which subsequently forms the optic tract with the optic nerve and retina. The antero-lateral part of the cerebral vesicle is prolonged forwards into two hollow processes, the hemisphere-vesicles, from which the cerebral hemispheres are subsequently developed. These vesicles are separated from one another by a median longitudinal fissure, whilst the hollow in the interior of each forms the lateral ventricle. On the floor of this vesicle a grey mass forms which may be named the basal nucleus, and which subsequently develops into the corpus striatum. The remaining portions of the walls of the vesicle form the cortex of the brain, the basal nucleus and cortex being continuous in the part which subsequently forms the anterior perforated space. When after a time fibres shoot down from the cortex to reach the central grey tube, and shoot upwards ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 469 from the central grey tube, corpora quadrigemiaa, and optic thalamus to reach the cortex, they pursue the shortest course by passing through the basal mccleus, so that the latter becomes divided into an inferior and external (the lenticular), and a superior and in- ternal portion (the caudate nucleus), the two being continuous with one another and with the cortex of the cerebrum in the anterior perforated space. The development of the basal nucleus therefore renders it probable that the corpus striatum is a modified portion of the cortex of the brain, thus confirming the view recently adopted by Wernicke. The fibres of which the fornix consists now appear on the inner wall of the hemisphere- vesicle, while the transverse fibres of the corpus callosum pass above the plane of the fornix to connect the cortex of one hemisphere with that of the other. Between the corpus callosum and the upper surface of the fornix, anteriorly, two thin layers of grey matter belonging to the inner surface of each hemisphere-vesicle are enclosed. These together form the laminae of the septum lucidum, and the cavity which separates them becomes the fifth ventricle. Each hemisphere-vesicle gives ofi" from its anterior part a hollow process which develops into the olfactory bulb. The longitudinal or collateral system of fibres, which connects the occipital lobe on the one hand and the temporal and frontal lobes on the other, form a relatively thick white layer in their passage through the middle lobe, which cuts ofi" the fifth from the remaining layers of the cortex of the Island of Reil, the detached portion being known as the claustrum. It consists, as we have seen, of fusiform cells analogous to those found in the fifth layer in other areas of the cortex, and which are probably asso- ciated in the latter with the system of arcuate fibres. The Convolutions. — The walls of the cerebral hemispheres consist at first of two smooth shell-like lamellae which include the cavities afterwards named the lateral ventricles. The first traces of the convolutions appear about the fourth month, the primary sulci appearing as slight depressions on the smooth surface. The Sylvian fissure begins as a cleft between the anterior and middle lobes about the fourth month, and is the first fissure to make its appearance after the great longitudinal fissure. Soon after- wards the fissure of Rolando appears ; it is followed by the parieto-occi- pital, and at a somewhat later period by the calloso-marginal fissure. After the fifth month, the secondary fissures develop rapidly, and all the convolutions and fissures make their appearance towards the seventh and eighth months. The hemispheres do not cover the optic thalami until the third month, at the fourth they reach the corpora quadri- gemina, and at the sixth month they cover a great part of the cerebellum. The convolutions of the human brain are divided xnio primary or fun- damental and secondary or accessory. The disposition of the fundamental convolutions is fixed, and corresponds closely with the arrangement of the convolutions in the brain of the monkey ; but the disposition of the acces- sory convolutions is variable, and they must be regarded as being super- added to the former in the course of evolution. The arrangement of the 470 ANATOMICAL AND PHYSIOLOGICAL INTKODUCTION. coQVolutions of a human embryo at the sixth month corresponds closely to that of the brain of the adult monkey. The fundamental convolutions are distributed along the margin of the great longitudinal and other primary fissures, while the accessory convo- lutions border the secondary fissures. The grey matter of the accessory is connected v?ith that of the funda- mental convolutions by means of arcuate fibres, while the former is not directly connected with the ascending and radiating fibres of the internal capsule. Another circumstance worth observing is that the grey matter of the summits of the convolutions is developed before that at the bottom of the fissures (Broadbent). It must be remembered that the growth of the brain is restrained at an early period of embryonic life by the skull. The distri- bution of the blood-vessels to the brain is such that the surface of the hemisphere must be more freely supplied with blood than the meduUary substance, and consequently the former will grow at a more rapid rate than the latter. If then the cortex grow at a more rapid rate than the medullary substance, and be at the same time restrained from growing freely outwards by the skull, the surface of the organ must be thrown into folds. The young nerve cells and fibres grow in the neighbourhood of the vessels and the older ones are thrust away from them. It follows that when two vessels run a more or less parallel course on the surface of the brain the younger nerve cells and fibres lie near each vessel, while the older ones occupy a position midway between them. If the surface of the brain were free to grow in all directions like the skin, the vessels them- selves would be thrust further apart during growth and the surface would remain more or less smooth ; but as the surface of the brain grows under pressure, the vessels cannot be thrust from each other ao a sufficiently rapid rate to keep progress with the growth of nerve tissue between them. The consequence is that either the growth of the nerve tissue between the two vessels must be arrested, or a fold must be formed so that the grey matter between them may pursue a curved instead of a straight course. If this be an approximately accurate account of the way in which the cerebral convolutions are formed, it will be readily seen that the earlier-formed nerve cells and fibres occupy the summits of the convo- lutions, while the later-formed cells and fibres occupy the bottom of the fissures. It may be noticed, in confirmation of this view, that the summits of the convolutions are alone directly connected with the pedun- cular and radiating fibres, while the grey matter of the fissures is only connected with them indirectly through that of the summits by means of arcuate fibres. The depth of the fissures may, therefore, be taken along with the complexity of the arrangement of the convolutions and other circumstances as a measure of the degree of development of the brain. The distribution of the blood-vessels of the cortex would also lead us to expect that the superficial layer next the pia mater is the embryonic layer of the grey matter, while the earlier-formed portions occupy the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 471 position furthest removed from the vessels, and consequently consist of the internal layers with caudate cells. § 682. Differences hetween the brain of the adult man and that of the higher mammalia and human infant.— The usual information given in anatomical works with regard to the size and weight of the human brain as compared with that of animals will be passed over here in order to insist upon less conspicuous, but probably not less important, differences. There has been a widely-spread belief that the large development of the frontal lobes is peculiarly characteristic of the brain of man, but some years ago Dr. Carpenter drew attention to the fact that in the lower forms of animals the cerebellum is entirely uncovered by the cerebrum, that it is only partially covered by the posterior lobes in the more intelligent animals, such as dogs and monkeys, and that it is only in man that the posterior lobes of the cerebrum completely overlap the cerebellum. Dr. Carpenter argued from this that the increase of the posterior lobes is more characteristic of advance in development than that of the anterior lobes. But he ignores the fundamental facts of development, while regarding superficial appearance. If we take the fissure of Rolando, or the central sulcus in animals, as the line which separates the frontal from the parietal lobe, it will be noticed how small a portion of the brain lies anterior to the sulcus in such animals as the rabbit {Fig. 226, r), which Fig, 226. Fig. 226 (Modified from Ferrier). Brain of Rabbit.— 0, Olfactory bulb ; r, Central sulcus ; X , Parallel sulcus ; M, Motor area ; A, Anterior or psychical area ; P, Posterior or sensory area. is one of the lowest animals in which the sulcus is developed. Even in the dog and monkey only a relatively small part of the brain lies anterior to this sulcus compared to the large mass which lies behind it. And a study of the development of the human brain shows that the occipital and parietal lobes increase rapidly at an early period in the develop- ment of the embryo, while the frontal lobes increase chiefly during the later months of foetal life. The portion which lies in front of the sulcus of Rolando in a six months human foetus (Fig. 227, r) is small, while the sulcus itself is directed vertically upwards in a line with the anterior ascending limb of the fissure of Sylvius ; the superior extremity being somewhat anterior to the inferior extremity. In the brain of the human adult the superior extremity of the sulcus of Rolando is pushed backwards, owing to the great increase of the frontal lobes, so 472 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. that a vertical line drawn from it would pass through the posterior ex- tremity of the horizontal limb of the Sylvian fissure. During the develop- ment of the human brain the superior extremity of the sulcus of Rolando therefore sufiers a backward displacement in order to make room for the increasing size of the anterior area of the cortex ; and, similarly, in the evolution of the human brain from the simian type the occipital lobes have undergone a posterior displacement in order to make room for the relatively large increase of size of the frontal lobes, hence the covering of the cerebellum is not caused directly by an increased size of the occi- pital, but indirectly by an increased size of the frontal lobes. Fig. 227. Fig. 227 (From Quain, after Wagner). External Surface of the Fcetal Brain at Six Months.~F, Frontal lobe. P, Parietal lobe. O, Ocoipital lobe. T, Temporal lobe, a, a, a, Slight appearance of the several frontal convolutions. S, Sylvian fissure ; S', its anterior division. C, Convolutions of the island, r, Fissure of Rolando, p, External part of the vertical fissure. Another remarkable feature in which the human brain differs from that of animals is the manner in which the Island of Reil is completely surrounded, and hidden out of view by deep convolutions. This is brought about by the large development of the posterior extremity of the inferior frontal, the inferior extremities of the ascending frontal and parietal convolutions, and of the supra-marginal, angular, and inferior temporo- sphenoidal gyri. It appears to me that the cortex of the central lobe, starting from the grey matter of the anterior perforated space, is the embryonic portion of the cortex of the brain, just as the central grey column is the embryonic portion of the grey matter of the spinal cord. The anterior perforated space is a point where the grey matter of the two nuclei of the corpus striatum and of the cortex of all the lobes of the brain meet, and it may therefore be regarded as the starting point of the whole of the grey matter derived from the primary cerebral vesicles. On the supposition that the portion of the central lobe which lies in the line of distribution of the Sylvian artery is the embryonic portion of the convolutions of the central or motor area of the brain, it may be expected that the earlier-formed portions of ISiese convolutions will be thrust up- wards towards the great longitudinal fissure, while the later-formed por- tions approach nearer and nearer to the root of the artery. According to ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 473 this supposition therefore the fundamental portions of the convolutions supplied by the Sylvian artery will be found near the great longitudinal fissure, and the accessory portion low down, near the root of the artery, the latter corresponding to the convolutions named the operculum, which is so highly developed in man. The great development of the supra-marginal and angular gyri is also a characteristic feature of the brain of man. FUNCTIONS OF THE ENCEPHALON. The functions of the medulla oblongata have already been described in detail, and those of the pons, corpora quadri- gemina, and crura cerebri in a general way. § 683. Functions of the Cerebellum. — The cerebellum is, according to the view adopted in these pages, an organ of com- pound co-ordination in space, and regulates the continuous muscular actions which are necessary for the maintenance of certain attitudes in space. Flourens observed that when a small portion of the cerebellum was removed from a pigeon, the animal's gait became unsteady, and that when larger portions were taken away, the movements became much more disorderly. Section of the middle peduncle gives rise to a forced movement, the animal rolling round its longitudinal axis, and the rotation being generally towards the side operated upon. Injury of the lateral lobe of the cerebellum, and probably of the fibres of the peduncle as they pass transversely through the pons, produces the same forced movements as section of the middle peduncle. Nothnagel concludes from experiments on rabbits that lesions which injure the fibres uniting the two sides of the organ occasion the greatest amount of motor disturbance. Ferrier found that electric stimulation of the cortex of the cerebellum in animals caused movements of both eyes, with associated movements of the head, limbs, and pupils. § 684. Functions of the Basal Ganglia.— The most generally received hypothesis, especially in England, with respect to the functions of these ganglia is that the optic thalami are concerned in the upward transmission and elaboration of cen- tripetal impulses ; and the corpora striata in the downward transmission and elaboration of centrifugal impulses. The 474 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. impulses elaborated by the thalami may either be transmitted anteriorly and laterally to the corpora striata, or upwards to the grey matter of the cortex, while the incitement to action may come to the corpora striata either from the thalami directly or from the cortex. When the impulses are transmitted directly from the thalami to the corpora striata, and from the latter downwards to the cord, then the basal ganglia may be regarded as the superordinates of the central grey tube ; but when the impulses are transmitted from the thalami to the cortex, and from the latter to the corpora striata, the basal ganglia, although still the superordinates of the central grey tube, are the subor- dinates of the grey matter of the cortex. Very serious objections have been urged against the view that the thalamus is the sensory ganghon of the opposite half of the body, but these have been fairly answered by Dr. Broadbent, to whose writings we are indebted for two most fruitful discoveries in the application of physiological principles to the elucidation of the phenomena of diseases of the nervous system. The first objection is, that lesion of the thalamus does not impair sen- sation in the same degree that motor paralysis is caused by injury of the corpus striatum ; but the reply is, that centripetal currents are more difi'usely conducted than centrifugal currents, and that this feature is as characteristic of the grey matter of the posterior horns of the cord as it is of the thalamus. Another objection is, that if the thalamus be the common sensory ganglion, lesion of it ought to cause not only hemi- ansesthesia, but also unilateral blindness and deafness. To this objection Dr. Broadbent replies by extending his principle of the bilateral association of the nerve-nuclei of muscles bilaterally associated in action to the func- tions of the nerves of special sense. Bilateral association of sensation ought to involve fusion of sensory nuclei, and the combination of sounds reach- ing the ears, and of light reaching the retinse, being completely fused into one sensation, the two auditory and the two optic nuclei ought to be fused practically into one, so that unilateral deafness or blindness from injury to one thalamus becomes thus impossible. Another objection to this view is, that while lesion of the thalamus is frequently unaccompanied by complete hemiansesthesia, it is sometimes accompanied by motor paralysis of the opposite side of the body ; from this it has been argued that the thalamus is a superior centre for reflex action (Crichton Browne). It must, however, be remembered that the pyramidal fibres of the internal capsule lie almost immediately external and inferior to the thalamus, so that disease of the latter may readily implicate the former, and then paralysis of the opposite side result. The hypothesis, therefore, that the thalamus is a centre for the com- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 475 pound co-ordination of centripetal impulses is not open to any insuperable objections, and accords better with facts than any other theory of its function. The compound co-ordinated centripetal impressions may be transmitted directly to the corpus striatum, and reflected downwards to the anterior horns and anterior root-zones of the cord, thus causing a compound reflex action, or upwards to the cortex of the brain, whex'e the impressions become correlated with feeling. There are no sufficient grounds for believing that the activity of the thalamus implies consciousness, even of the most rudimentary kind. A compound difiers from a simple reflex action not only as being more complex, but also as consisting of a suc- cession of different actions. The act of sucking in an infant is a complex act, but it consists of a series of similar complex actions in response to a series of similar impressions, and this action may be taken as a good example of reflex actions in general. But when a chicken has just burst the shell, and almost immediately begins to pick grains of food ofi" the ground, the necessary actions are not only complex, but consist of a succession of different complex actions in response to different complex im- pressions. There is no reason to believe that the latter action is a con- scious one, any more than that of sucking in an infant ; but while the latter is a simple reflex action, and co-ordinated in the central grey tube, the former is a compound reflex action, and co-ordinated in the basal ganglia acting in association with the central grey tube and probably also with the cerebellum. When impressions are made upon a large number of the end organs of the afferent nerves, these, after being first co-ordinated in the posterior part of the grey matter of the central grey tube, undergo, on ascending, a second co-ordination in the thalami, whereby they are integrated in various ways, and reduced to something like serial order. When the centripetal impulses so arranged are transmitted to the corpora striata, and reflected downwards, they give rise to a succession of muscular contractions ; when again they are transmitted to the cortex — which is, as we have already remarked, the organ of doubly compound co-ordination in time — their serial order adapts them for evoking the rhythmical sequences of centrifugal impulses which regulate complex psychical actions. The corpus striatum, on the other hand, is a centre for the compound co-ordination of centrifugal impulses for the opposite half of the body. "When it acts in obedience to impulses received from the optic thalamus, it is an organ of compound reflex action. All the actions which are regarded as inherited instincts, or which through long-continued repetition have assumed the cha- racter of acquired instincts, are of the nature of compound reflex actions; they are or have become independent of conscious- ness, and are co-ordinated in the basal ganglia. But the corpus striatum is supposed to act in obedience to impulses received 476 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. through the cortex of the brain. We have already seen that there is an uninterrupted connection between the cortex and grey matter of the cord by means of the pyramidal fibres, and we must now endeavour to differentiate the functions of the cortex when it acts through the latter fibres and through the corpus striatum respectively. A simple illustration will make this clear. When a child is learning to write, the muscles of the thumb, index, and middle fingers are moved in separate groups, so that the fingers are ultimately brought to a proper attitude for holding the pen. Subsequently the separate groups of muscles are brought successively into action, whereby the point of the pen is moved upwards, downwards, and laterally, so as to produce the elementary strokes of writing. These actions, described in subjective terms, are not simply conscious, but involve that active consciousness which constitutes attention, and they are also deliberate, the outward sign of deliberation being slowness of execution. The centrifugal impulses which initiated these movements may be presumed to have passed through the pyramidal fibres. After long-continued habit, however, the actions involved in writing are to a large extent, if not wholly, unconscious, and demand no deliberation, and this absence of deliberation is accompanied by extreme rapidity of execution. The centrifugal impulses regulating these actions are co-ordinated in the corpus striatum, under the guidance of a relatively small number of impulses from the cortex. This illustration also shows that the progress of education is from actions which are at first regulated through the pyramidal fibres, to actions which are regulated through the corpus striatum. The characteristics of the actions regulated through the pyramidal fibres are, that they are complex, slowly executed, and grouped iu an un- usual manner ; while the characteristics of the actions which are regulated through the corpus striatum are, that they are quickly executed, and arranged in frequently repeated combinations. Now, the slowly executed movements grouped in unusual ways precede in the order of development the quickly executed and habitual movements, and the structural corre- lative of this fact is, that in the course of development the pyramidal fibres assume a medullary sheath some time before the fibres in the crusta which connect the cord with the corpus striatum. All the complex move- ments which animals manifest in response to emotional disturbances are ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 477 organised in the corpora striata. The attitude expressive of fear and anger assumed by a cat when threatened by a dog may be taken as a familiar example of such actions. Mr. Darwin's description of this attitude is that the cat " arches its back in a surprising manner, erects its hair, opens its mouth, and spits," The regulation of the muscular movements concerned in producing this attitude is organised mainly in the corpora striata, but the incitement to the action of these centres in such a case comes from the cortex. My friend Dr. Noble, of Manchester, whose work " On the Human Mind in its relations with the Brain and Nervous System " was so much in advance of the time in which it was written, was the first to suggest that the movements which are in relation with the desires and emotions are regulated through the basal ganglia acting in subordination to the cortex of the brain ; but this view, like many of his other opinions, did not then attract the attention it deserved. To illustrate the functions of the basal ganglia, let us suppose that an impression is made on the retina by a minute object, such as a fly, approaching the eye. The eyelids immediately close. This action is purely reflex, and is determined by the corpora quadrigemina and cord, uninfluenced by the basal ganglia Part of the disturbance, however, is conveyed to the optic thalami, and by them co-ordinated in such a way that on reaching the cortex of the brain they give rise to a sensation, or even to an indistinct perception, but the closure of the lids is quite independent of, and prior in time to, the sensation or perception. Let us now suppose that the impression on both retinee is made by a larger body, such as a cricket-ball, at a considerable distance from the eyes, but moving towards them. The disturbances produced are conducted inwards by the optic nerves and the afferent nerves of the ocular muscles, and after being elaborated by the sensory part of the grey matter of the pons and corpora quadrigemina, some of them pass upwards to reach the cortex through the sensory fibres of the internal capsule, while others are con- ducted to the thalami, and after having undergone a second elaboration and reduction to something like serial order, they also are transmitted to the cortex. The mental correlative of the cortical disturbance is a perception of the object and of its position in space, and of the rate and direction of its motion. Centrifugal impulses may now be sent from the cortex to the inferior centres, which will eventuate in a series of movements, either to catch the ball or to avoid collision with it. One man, in whom no special aptitude has been organised with respect to the motion of the ball, may simply move his head to one side to avoid collision. The slower the execution is the more sure we are that it has not been frequently repeated in the previous experience of the individual, and that it has been determined by conscious and volitional mpulses. In such a case the volitional or centrifugal impulses are con- ducted outwards through the pyramidal fibres, and the corpora striata have had nothing to do with it. Another man, or rather a woman, on 478 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION, seeing the ball may exhibit the outward manifestations of alarm by facial expression or screaming, and execute a series of locomotive actions far greater than necessary to avoid collision with the ball, and the greater these outward manifestations are, the more certain we may be that the sensory impressions on reaching the cortex have caused a profound emotional disturbance, and that the centrifugal impulses reach the periphery through the corpora striata. But a third man, instead of endeavouring to avoid collision, may put up both hands so as to catch the ball. Now, the centrifugal impulses may pass in this case either through the pyramidal fibres or corpora striata, according to circum- stances. If the action have been frequently repeated so that it be done with precision, and without a feeling of conscious effort, its regula- tion is organised in the corpora striata ; and if it be done awkwardly, and with the inward feeling and outward manifestation of a conscious effort, then the centrifugal impulses have passed through the pyramidal fibres. It must, however, be admitted that the foregoing account of the func- tions of the basal ganglia is by no means fully established. We have already stated that the internal surface of the optic thalamus is lined by a layer of grey substance which represents the upper end of the central grey tube, and that the upward continuations of the anterior root-zone of the cord terminated in this ganglion, and consequently it must be presumed that a portion at least of the thalamus is endowed with motor functions. The opinion that the optic thalami is a high reflex centre has been ably sustained by Dr. Crichton Browne on pathological grounds. The anatomical difficulties which stand in the way of regarding the corpus striatum as an intermediate ganglion between the cortex of the brain and the central grey tube are also very great. The latest researches of Wer- nicke appear to show, as we have seen, that neither the lenticular nor the caudate nucleus possess radiating fibres ; and if this be the case, the corpus striatum must be regarded as a nerve centre co-ordinate with and not subordinate to the cortex. Ferrier observed that when the corpora striata were stimulated by a strong interrupted current, the muscles of the oppo- site side of the body became strongly contracted ; but it is impossible to prevent even weak currents through the corpus striatum from affecting the fibres of the internal capsule, and the spasm of the opposite side would be probably caused by irritation of the fibres of the pyramidal tract. AVe shall hereafter see that when hemiplegia occurs from hsemorrhage into the corpus striatum, the patient recovers if the fibres of the pyramidal tract remain uninjured. Nothnagel found that destruction or injury to a particular part of the caudate nucleus gave rise in the rabbit to remarkable forced movements. § 685. Functions of the Cortex of the Cerebrum. — The cortex of the cerebrum is probably the exclusive seat of psychical action, and there seem to be no grounds for .believing that the activity of any other portion of the encephalon is necessarily connected with ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. 479 even the crudest consciousness. But before we can refer certain states of consciousness to definite processes in the cortex of the cerebrum, it is necessary to have a classification of mental phenomena, for no decided progress can be made in interpreting the results of experiments on the cortex of the brain until the true nature of a psychical action is defined and some rational classification of psychical states is adopted by physiologists. Nature of Psychical Actions. — We have already seen that simple reflex adapted actions consist of a series of simiiarcomplex movements evoked by a series of similar impressions, and that compound reflex adapted actions consist of a series of different complex movements evoked by a series of different impressions ; and we must now endeavour to show wherein true psychical action differs from simple and compound reflex actions. Reflex actions, both simple and compound, consist of three factors : (1) conduction to a nerve centre of an impression made on the surface ; (2) reduction to order of these impressions in the centre ; and (3) conduction of these outwards, with the muscular contractions resulting from them. But, as has been frequently stated by Mr. Herbert Spencer, four factors may be distinguished in every psychical action. To quote Mr. Spencer's own language, " there is {a), that property of the external objects which primarily affects the organism — the taste, smell, or opacity; and, connected with such property, there is in the external object that character (6) which renders seizure of it, or escape from it, beneficial. Within the organism there is (c), the im- pression or sensation which the property {a) produces, serving as stimulus ; and there is, connected with it, the motor change {d), by which seizure or escape is effected. Now psychology is chiefly concerned with the connection between the relation ah, and the relation cd, under all those forms which they assume in the course of evolution. Each of the factors, and each of the relations, grows more involved as organisation advances. Instead of being single, the identifying attribute a, often becomes, in the environment of a superior animal, a cluster of attributes, such as the size, form, colours, motions, displayed by a distant creature that is dangerous. The factor h, with which this distant combination of attributes is associated, becomes the congeries of characters, powers, habits. 480 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. which constitutes it an enemy. Of the subjective factors, c becomes a complicated set of visual sensations co-ordinated with one another and with the ideas and feelings established by experience of such enemies, and constituting the motive to escape ; while d becomes the intricate, and often prolonged, series of runs, leaps, doubles, dives, &c., made in eluding the enemy," Classification of P/sychical States. — Various classifications of mental states might be adopted, but the best is clearly that which involves the fewest assumptions and theoretical implica- tions, and which will enable us at the same time to connect mental phenomena with the facts of development and experi- mental physiology. " It would be the greatest benefit to mental science," says Max Miiller, " if all such words as perception, intuition, remember- ing, ideas, conception, thought, cognition, senses, mind, intellect, reason, soul, spirit, etc., could for a time be struck out of our philosophical dictionaries, and not be admitted again till they had undergone a thorough purification." This passage expresses a state of mind which has been felt by almost everyone who has seriously engaged in psychological study ; and Mr. Herbert Spencer, whose great works have formed an era in philosophy and psychology, has, with his usual breadth of treatment, adopted a classification which does in a great measure avoid the use of these words, except indeed where the use of them admits of accurate definition. We shall avail ourselves of this classification in our future remarks. Mr. Spencer subdivides all mental states into volitions, cog- nitions, and feelings ; and the first of these subdivisions may be disposed of in a few words. " Will," says Mr. Herbert Spencer, " is a simple homogeneous mental state, forming the link between feeling and action, and not admitting of sub- divisions." " Cognitions," says Mr. Spencer, " are those modes of mind in which we are occupied with the relations that subsist among our feelings." They are divisible into four great sub-classes. (1) " Presentative cognitions, or those in which conscious- ness is employed in localising a sensation impressed on the organism." ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 481 (2) " Presentative-representative cognitions, or those in which consciousness is occupied with the relations between a sensation or group of sensations and the representations of those various other sensations that accompany it in experience" (perceptions). (3) "Representative cognitions, or those in which conscious- ness is occupied with the relations among ideas or represented sensations, as in all acts of recollection" (concrete ideas). (4) "Re-representative cognitions, or those in which the occu- pation of consciousness is not by representation of special rela- tions that have before been presented to consciousness, but those in which such represented special relations are thought of merely as comprehended in a general relation — those in which the concrete relations once experienced, in so far as they become objects of consciousness at all, are incidentally represented along with the abstract relation which formulates them" (abstract ideas). " It is clear," Mr. Spencer adds, " that the process of representation is carried to higher stages as the thought becomes more abstract." Feelings, or those modes of mind in which we are occupied, not with the relations subsisting between our sentient states, but with the sentient states themselves, are divisible into four parallel sub-classes. (1) Presentative feelings are those in which a corporeal im- pression is regarded as pleasure or pain (sensations). (2) Presentative-representative feelings are those in which a sensation or a group of sensations arouses a vast group of repre- sented feelings (emotions). (3) Representative feelings, comprehending the ideas of the emotions when they are called up, apart from the appropriate external excitements, such as the emotions excited by a vivid description. (4) Re-representative feelings are those more complex sen- tient states that are less the direct results of external excite- ments than the indirect or reflex results of them, such as the love of property, which consists of the represented advantages of possession in general, which is not made up of certain con- crete representations, but of the abstracts of many concrete representations. FF 482 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. "The classification," Mr. Spencer proceeds, "here roughly indicated, and capable of further expansion, will be found in harmony with the results of decided analysis aided by develop- ment. Whether we trace mental progression through the grades of the animal kingdom, through the grades of mankind, or through, ithe stages of individual growth, it is obvious that the advance, alike in cognitions and feelings, is, and must be, • from the presentative to the more and more remotely represen- tative. It is undeniable that intelligence ascends from those simple perceptions in which consciousness is occupied in locali- sing and classifying sensations, to perceptions more and more compound, to simple reasoning, to reasoning more and more complex and abstract, more and more remote from sensation. And in the evolution of feelings there is a parallel series of steps. Simple sensations ; sensations combined together ; sen- sations combined with represented sensations; represented sen- sations organised into groups in which their separate characters are very much igferged ; representations of those representative groups in which the original components have become still more vague. In both cases the progress has necessarily been from the simple and concrete to the complex and abstract ; and as with the cognitions so with the feelings, this must be the basis of classification." It is not, perhaps, possible in the present state of our know- ledge to separate the cortex of the brain into areas exactly corresponding to the various subdivisions of Mr. Herbert Spencer's classifications. The cortex may, however, be sub- divided into areas which will correspond with the leading features of this classification. 1. The cortex of the brain must mainta-in some connection with the surface of the body, by means of which impressions made on the latter occasion molecular changes in the former. The parts at which the cortex is connected with the centripetal system of nerves may be called sensory inlets, and if the portion of the cortex containing these inlets can be isolated from the remaining portions of the cortex, there can be no serious objections to calling it the sensory area of the cortex. And, indeed, if the inlets from the various senses can be more or less isolated from one another, each may be called a ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 483 sensory centre. We have already seen that the posterior third of the posterior division of the internal capsule contains cen- tripetal fibres for the opposite half of the body, and that these radiate in the centrum ovale to terminate in the convolutions of the occipital and tempore- sphenoidal lobes, or the area of the cortex, which is supplied by the posterior cerebral artery. That the fibres of the tract which ascends in the external third of the crusta and posterior part of the external capsule are sensory has been proved by the experiments of Veyssiere, and confirmed by Carville and Duret, Raymond, and others. Veyssiere showed that section of the posterior part of the in- ternal capsule lying between the lenticular nucleus and optic thalamus was followed by hemianaesthesia of the opposite side of the body. Fig. 228. ' L Fig. 228 (After Carville and Duret). Transverse Section of the Brain of a Dog on a level with the Corpora Albicantia. — O, O, Optic thalami; S, S, Caudate nuclei ; L, L, Lenticular nuclei ; P, P, Posterior region of the internal capsule ; X, Section of the posterior part of the internal capsule determining hemi- anajsthesia ; A, A, Cornu Ammonis. 2. The cortex of the brain must be connected with the muscular system, in order that the reactions of the organism upon its environment may be regulated in correspondence with the impressions made upon it. The parts at which the cortex is connected with centrifugal fibres may be called motor outlets, and if the portion of the cortex which contains these can be isolated from the remaining portions of the cortex it may be called the 'motor area. And if the motor outlet for a particular movement can be isolated from the outlets for other movements there can be no great harm in calling it a motor centre. 484 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. A cortical motor centre then constitutes the link between cortical activity on the one side, and voluntary muscular con- tractions on the other ; and volition being the link between feeling and action, the cortical motor centres may be regarded as the structural counterparts of volitions. We have already seen that the pyramidal tract contains the centrifugal fibres from the cortex of the brain, and this has also been determined experimentally by Veyssiere, who found that section of the anterior two-thirds of the internal capsule was followed by hemiplegia of the opposite side, unaccompanied by sensory paralysis. Fig. 229. Fig. 229 (After Carville and Duret). Transverse Section of the Brain of the Dog, fire millimetres in front of the optic commissure.— S, S, The caudate nuclei of the corpora striata ; P, P, Peduncular fibres (the internal capsule) ; L, Lenti- cular nucleus ; R, Stylet, by means of which Veyssiere produced section of the internal capsule at (x). But the pyramidal tract is not, according to most anatomists, the only- outlet from the cortex of the brain. Leaving out of account the centri- fugal fibres which probably connect the cortex of the cerebrum with the eerebellmn, there still remain the fibres which connect the cortex of the cerebrum with the central grey tube through the intermediation of the corpus striatum. The cortical actions which are regulated through the corpus striatum and pyramidal tract are often, although not always, an- tagonistic to one another. The excitation of the cortex which is the cor- relative of feeling, whether the latter be pleasurable or painful, always tends to find a vent in immediate action, while a great portion of our voluntary efforts are directed to restrain action, and to postpone the im- ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 485 mediate gratification of the feelings in order to accomplish remote ends. Excitation, for instance, of the cells in the cortex which are in immediate contact with the terminations of the centripetal nerves in the sixmmits of the convolutions of the posterior area of the cortex tends to be conducted immediately outwards along the centrifugal fibres which connect these convolutions with the corpus striatum. If these excitations are conducted at once outwards, they give rise to movements which have been named sensori-motor ; but if the excitations, instead of being conducted at once . outwards, pass from the cells in connection with the termination of one bundle of centripetal fibres (vision) to those in connection with another bundle (tactile), so that the relation between the two feehngs comes into prominence, then a presentative cognition is formed. When, for instance, the centripetal impulse received in a convolution from the irritation caused by a thorn in the finger is brought into connection with the impressions received through the optic and other centripetal nerves, and which, on reaching the cortex, becomes the correlative of the con- sciousness of the finger itself, then a cognition of the relationship of pre- sentative feeling is formed. Now, a presentative cognition does not usually, Hke a presentative feehng, immediately result in action. The excitation expends itself in the former in producing excitation of other groups of cells in the cortex, the transition from one group to another giving rise to other presentative and representative cognitions, vmtil finally the motor area is reached, and the excitation passes out along the pyramidal fibres. Subjectively considered, the cognition of the thorn and finger would call up other cognitions connected with these by previous experiences, as that of a pin, and probably the highly representative cognitions of the general properties of the lever, imtil finally the pin is voluntarily grasped and rightly appUed for the removal of the thorn. This action is very diflferent from that which impels a dog to lick with his tongue the foot in which a thorn is lodged. The latter is a sensori-motor or doubly compound reflex action, and in immediate relation with the cortical excitation which causes the feeling of pain, while the former resiilts from a series of com- plex cortical excitations, some of which check the tendency to immediate action, until by-and-by complex actions result which are guided by wide experience and adapted to remote ends. The movements which result immediately from the feelings have been called sensori-motor, percipio- motor, and ideo-motor, on the supposition that they occurred in response to the cognitions ; but it would be better to call the movements which result from a presented feeling a doubly compound reflex action, that from a presentative-representative feeling a trebly compound reflex action, and that from a representative feeling a quadruply compound reflex action, and so on in an ascending scale, according to the degree of the complexity of the feehng. When, however, a series of cognitions intervene in the mental operations between the feeling which prompts a movement and the movement itself, the resulting jnuscular adjustment is a voluntary one, and is regulated through the pyramidal fibres. When, for instance, 486 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. Leverrier, prompted by the highly representative feeling of a desire for discovery, directed his telescope to a certain spot in the heavens, and dis- covered Neptune, the requisite muscular adjustments necessary for carry- ing out this action were preceded in his mind by a long series of involved and highly representative cognitions; and these muscular adjustments themselves were, to a large extent, voluntary. ■ 3. The region of the cortex supplied by the anterior cerebral artery still remains to be connected with some kind of mental activity. We have seen that the area supplied by the posterior cerebral artery is the sensory area, and consequently excitation of this area is the correlative of the presentative and presenta- tive-representative cognitions and feelings, while excitation of the area supplied by the middle cerebral artery is the cor- relative of volition. Excitation of the cortical area supplied by the anterior cerebral artery is the correlative again of the representative and re-representative cognitions and feelings. It is somewhat difficult to find a name which will be expressive of the functions of this area, and if we consent to call it the ideational area, it must be remembered that it is no less likely to be the anatomical substratum of the higher emotions than of the higher intellectual operations. § 686. Anatomical Substratum of Consciousness. — It is well recognised that a large number of psychical actions may take place in an unconscious manner. Leaving out of consideration the phenomena of dreaming and somnambulism, we may in- stance such a familiar fact as that a man may read aloud whole pages of a book while his mind is engaged in solving a difficult problem, and he is wholly unconscious of what he is saying, yet the muscular movements engaged in reading are co-ordinated in the cortex of the cerebrum. If, under these circumstances, the eye falls on an unusual word, consciousness is directed to it for a moment, and the reading may then go on unconsciously as before. It would therefore appear that impressions which have been frequently repeated in experience may pass up to the cortex and give rise to complicated motor impulses from the cortex without being attended by consciousness ; but that when the impressions made on the sensory organ present an unusual combination, consciousness is aroused. Unusual combinations ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 487 of sensory impressions are, therefore, probably conducted to and through the cortex in channels which are only partially open, while the habitual combinations pass in channels which are open and well defined. In intellectual efforts the highest consciousness is aroused when the mind is contem- plating new combinations of presentative and representative impressions, or, to translate this into the language of physics, when the organism is adjusting itself to new combinations of circumstances and events. In other words, the highest intel- lectual consciousness is aroused during the time that a new organisation in the cortex of the brain is being superadded to the existing one, while excitation of the portion of the cortex which is already thoroughly organised is attended by little or no consciousness. It cannot be supposed that the large cells, with the distinct processes and definite connections found in the internal division of the third layer of the cortex, will readily undergo structural changes in the healthy adult, and it is much more probable that any new alteration of structure in the cortex will proceed from the small cells of the external layers of the cortex. The first layer may probably be regarded as an embryonic layer without any active nerve functions, and consequently the second layer and external portion of the third layer of the cortex, the cells of which do not possess definite connections with one another or with nerve fibres, must be regarded as the areas, excitation of which is attended by the highest consciousness. Experiments on animals have proved, as we have seen, that the fibres which pass through the posterior third of the posterior division of the internal capsule are sensory, but the sensory area of the cortex is also connected with the periphery, through the optic thalamus and its radiating fibres. It is probable that impressions which have been frequently repeated in experience pass through the optic thalamus and its radiating fibres, and that they give rise to little or no consciousness on reaching the cortex. It may be presumed, on the other hand, that unusual combinations of impressions are conducted through the posterior fibres of the internal capsule, and give rise on reaching the cortex to distinct consciousness. 488 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. § 687. Experimental Determination of the Functions of the Cortex of the Brain. 1. Motor Centres. Experiments hy Stimulation. —When the cerebrum is removed slice by slice there is a gradual loss of intelligence and volition, and consequently Flourens, who conducted these experiments, concluded that the brain acted, as a whole, without any special functions being assigned to special parts. Hughlings-Jackson, however, drew attention to the fact that focal disease of the cortex of the brain may occasion epileptiform convulsions, localised to particular groups of muscles. Hitzig and Fritsch showed that the local application of the galvanic current to particular parts of the cerebral convolutions gives rise to definite movements of various groups of muscles. These experiments were extended and rendered more definite by Terrier, who used the faradic instead of the galvanic current as a means of stimulation. The motor centres as determined by Terrier in the monkey are represented in Figs. 230 and 231, while the corresponding parts in the human brain are shown in Figs. 232 and 233. Fig. 230. Fig. 230 (After Terrier). The Left Hemisphere of the Monkey. Burdon-Sanderson states that the motor reacti ons to cortical stimulation are not prevented from taking place by a horizontal incision carried some distance from the surface. This simply shows that a faradic current applied to the surface of the brain is conducted into the centrum ovale and stimulates the ends of the divided pyramidal fibres, but it does not show that the cortex is non-excitable. Burdon-Sanderson also found that local stimulation of the white matter immediately surrounding the corpus striatum produces localised move- ments similar to those caused by stimulation of the corresponding cerebral surface. This experiment, like the last, shows that the fibres of the pyramidal tract are excitable, but it proves nothing with regard to the excitability or non-excitability of the cortex. If the motor area of the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 489 cortex be removed, excitation of the subjacent white substance causes the same movements as excitation of the motor centre itself. In such a case the ends of the fibres of the pyramidal tract which issued from the motor centre are now exposed, and excitation of them causes the same kind of motor reaction as that caused by excitation of the motor centre itself. If the animal, however, survive the operation, the pyramidal fibres undergo secondary descending degeneration, and excitation of the scar or Fia. 231. Fig. 231 (After Ferrier). Up2nr Sin-face of the Hemisphere of the Monkey. 1, Advance of the opposite leg as in walking. 2, Complex movements of the thigh, leg, and foot, with adapted movements of the trunk. 3, Movements of the tail. 4, Retraction and adduction of the opposite fore limb. 5, Extension forward of the opposite arm and hand, as if to reach or touch something in front. Circles (a), (6), (c), (d), Individual and combined movements of the fingers and wrists, ending in clenching of the fist. 6, Supination and flexion of the forearm, by which the hand is raised towards the mouth. 7, Action of the zygomatics, by which the angle of the mouth is retracted and elevated. 8, Elevation of the ala of the nose and upper lip, with depression of the lower lip, so as to expose the canine teeth on the opposite side. 9, Opening of the mouth with protrusion of the tongue. 10, Opening of the mouth with retraction of the tongue. 11, Retraction of the angle of the mouth. 12, Eyes opening widely, pupils dilating, head and eyes turning towards the opposite side. 13 and 13', Eyeballs moving to the opposite side. Pupils generally contracting. 14, Sudden retraction of the opposite ear. 15, Subiculum cornu Ammonis. Torsion of the lip and nostril on the same side. 490 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. its neighbourhood no longer produces the particular movements charac- teristic of the destroyed area (Albertoni and Michieli). Experiments hy Destxuction of Portions of the Cortex. — It has been observed that removal or destruction of a motor centre is followed Fig. 232. Figs. 232 and 233 (After Ferrier). Side and Upper Views of the Brain of Man. The figures are constructed by marking on the brain of man, in their respective situations, the motor areas of the brain of the monkey as determined by experiment, and the description of the effects of stimulating the various areas refers to the brain of the monkey. 1 (On the postero-parietal lobule), Advance of the opposite hind hmb as in walking. 2, 3, 4 (Around the upper extremity of the fissure of Rolando^, Complex move- ments of the opposite leg and arm, and of the trunk, as in swimming. a, b, c, d (On the ascending parietal convolution), Individual and combined movements of the fingers and wrist of the opposite hand. Prehensile movements. 5 (At the posterior extremity of the superior frontal convolution), Extension forward of the opposite arm and hand. 6 (On the upper part of the ascending frontal convolution), Supination and flexion of the opposite forearm. 7 (On the median portion of the ascending frontal convolution), Retraction and elevation of the opposite angle of the mouth by means of the zygomatic muscles. 8 (Lower down on the same convolution), Elevation of the ala nasi and upper lip with depression of the lower lip, on the opposite side. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 491 by inability to execute the movements assigned to the area (Hitzig, Ferrier), but it has subsequently been found that the paralytic symptoms disappear when the animal operated upon survives some days (Nothnagel, Hermann, Goltz). Hermann removed cortical motor centres from dogs, Fig. 233. 9, 10 (At the inferior extremity of the ascending frontal and posterior extremity of the third frontal convolution), Opening of the mouth with (9) protrusion and (10) retraction of the tongue. Region of Aphasia. 11 (At the inferior extremity of the ascending parietal convolution), Retraction of the opposite angle of the mouth, the head turned slightly to one side. 12 (On the posterior portions of the superior and middle frontal convolutions). Eyes opening widely, pupils dilating, and the head and eyes turning towards the opposite side. 13, 13' (On the supra-marginal lobule and angular gyrus), The eyes moving towards the opposite side with an upward (13) or downward (13') devia- tion. Pupils generally contracting. (Centre of vision. ) 14 (On _ the infra-marginal or superior temporo-sphenoidal convolution). Pricking up of the opposite ear, head and eyes turning to the opposite side, and pupils dilating largely. (Centre of hearing.) Ferrier moreover places the centres of taste and smell at the extremity of the temporo-sphenoidal lobe, and that of touch in the gyrus uncinatus and hippo- campus major. 492 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. and found that the paralysis, which immediately followed the operation, disappeared in a few days. These results were afterwards confirmed by Carville and Duret, who also found that the restoration of motor power could not have been due to the corresponding centre of the opposite hemisphere, inasmuch as subsequent destruction of the latter produced the usual paralysis on the side opposite to the lesion, but did not cause a repetition of the paralysis on the side opposite to the first lesion. These authors suppose that portions of the same hemisphere took up the func- tions of the destroyed centre. Fig. 234. Fig. 234 (After Broca and Gomier). External Convex Surface of the Brain of the Adult Monkey. — Fissures : R, Fissure of Rolando : S/, Fissure of Sylvius ; pf, Parallel fissure ; pof, External perpendicular or parieto-occipital fissure ; pcf, Prae-central fissure. Convolutions: A, Ascending frontal convolution; B, Ascending parietal convolution; Fi, Fa, Fa, First, second, and third frontal convolutions ; ag, Angular gyrus ; img, Infra-marginal gyrus ; hi, Horizontal lobule ; ol, Occipital lobe. Motor Centres : 1, Movements for rotation of head and neck ; 2, Movements of muscles of the face ; 3, Movements of the tongue and jaws; 4, Movements of anterior extremity; 5, Movements of posterior extremity ; 6, Movements of the ocular muscles ; 7, Movements in relation with sense of hearing. Goltz removed parts of the cerebral surface by washing the nervous substance away by a stream of water, and he came to the conclusion that the paralytic phenomena did not depend so much upon the locality as the extent of the injury. He also found that the paralysis disappeared in a short time, whatever might be the portion of brain removed. He was able in one case to remove the greater part of one hemisphere, and yet recovery of motor power took place, clumsiness in the execution of certain move- ments alone remaining ; this Goltz attributed to a deficiency of tactile sensibility. He thinks that the paralytic phenomena are caused by an inhibitory action produced by the injury on lower centres, similar to the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 493 temporary paralysis of the automatic centres in the lumbar portion of the spinal cord produced by section in the dorsal region. But examples of a localised destroying lesion of the cortex of the brain in man have now multiplied to such an extent that there is no room for doubt with regard to the main symptoms caused by them, whatever may be the interpretation. When a patient has been unable to move his right arm and hand for months, and when after death a destructive lesion of the cortex of the opposite hemisphere is observed strictly limited to the middle of the ascending frontal and parietal convolutions, and when cases of this nature occur with sufficient frequency to show that the connection between the lesion and symptoms during life is not accidental, it is idle for any physiologist to deny that the paralysis was due to destruction of the cortex in that area, inasmuch as only temporary paralysis would be caused by a similar lesion in the dog. The fact that paralysis following cortical lesions in the dog is only temporary shows that diflferences must exist with regard to the relation which obtains between the highest nerve centres and muscular movements in man and the dog respectively. And it is not difficult to point out where some of these differences lie. Fig. 235. .-pcf Fio. 285. External Convex Surface of the Human Brain. — Fissures : R, Fissure of Rolando ; S/, Fissure of Sylvius ; p/, Parallel fissure ; ipf, Interparietal fissure ; pof, External parieto-occipital fissure. Convolutions and Lobules : A, Ascending frontal; B, Ascending parietal convolutions; Fi, Fa, Fs, First, second, and third frontal convolutions; Pi, Superior parietal lobule; Pa, Supra-marginal gyrus ; Ps, Angular gyrus ; Oi, O'^, Os, First, second, and third occipital con- volutions ; Ti, T2, T3, First, second, and third temporo-sphenoidal convolu- tions. Motor Centres : 1, Movements for rotation of head and neck ; 2, Move- ments of the upper facial muscles ; 2', Movements of the lower facial muscles ; 3, Movements of the tongue and jaws ; 4, Movements of superior extremity ; 5, Movements of inferior extremity ; 6, Movements of the ocular muscles ; 7, Movements in relation with the sense of hearing. 494 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. We have already aeen that paralysis of the external rectus muscle of the one side and of the internal of the other occurs in most cases of sudden hemiplegia in man, causing a conjugate deviation of the eyes away from the paralysed side. This paralysis disappears in a few days, and is almost exactly similar to what occurs in the paralyses of cortical lesions caused in the dog. And even injury to the deep-seated parts of the brain in the dog, such as the crus cerebri, does not cause a hemiplegia at all comparable to the hemiplegia which occurs in man. In lesion of the right crus cerebri in the dog there is only a very partial hemi- plegia. When standing the animal carries his body towards the right, his eyes are directed to the right, and his head is also rotated to the right, and if the animal move he goes round in a circle after his tail (Broadbent). It would not be more preposterous to tell us that because injury of the crus cerebri causes a mouvement de manege in the dog it cannot therefore cause hemiplegia in man, as to say that because rapid recovery from the paralysis caused by cortical lesions takes place in the dog the affections caused by similar lesions in man is not due to the destruction of a cortical centre. The disappearance of paralysis of the limbs in the dog corresponds exactly to the disappearance of conjugate deviation of the eyes in man, and the explanation which suffices for the one will probably suffice for the other (§ 90). But even Goltz admits that some movements in the dog become more or less permanently paralysed. For instance, he may use his forepaw to drag bones and other morsels of food from under a table, and he may also be taught to perform special tricks with his paws ; all such special movements become more or less permanently lost after portions of the cortex have been removed. This shows that the purely voluntary actions are more or less permanently lost, while paralysis of the automatic actions concerned in ordinary locomotion rapidly disappears. Goltz found that the animals operated on could after a time be trained or educated to perform special actions with their paws, a fact which shows that a new organisation takes place more readily in the brain of the dog than in that of man, but it is quite probable that new structural arrange- ments may also take place to a certain extent in the brain of man aftej partial injury. 2. Sensory Centres. It has already been seen that the centripetal fibres terminate amongst the cells of the second and third layers of tlie cortex without forming any direct connection with them, while the fibres of the pyramidal tract take origin in the axis-cylinder processes of the giant-cells of the internal portion of the third layer. It may, therefore, be suspected that the cen- tripetal currents will pass in a much more diffused manner through the cortex than the centrifugal, just as it is found that the former pass in a more diffused manner through the spinal cord than the latter. It is not therefore likely that the sensory inlets are as definitely localised as the motor outlets. ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 495 Experiments hy Stimulation. — On stimulating the angular gyrus Ferrier obtained various movements of the eye and associated move- ments of the head, and he regarded the phenomena observed as being " merely reflex movements on the excitation of subjective visual sensation." He, therefore, concluded that the angular gyrus and sur- rounding grey matter constituted the centre of vision. On somewhat similar grounds he placed the auditory centre in the superior temporo- sphenoidal convolution, the centres of taste and smell at the extremity of the temporo-sphenoidal lobe, and that of touch in the gyrus unciuatus and hippocampus major. But these experiments, although exceedingly interesting and important as being the first to break ground in a new- territory, are by no means conclusive. Dr.- Ferrier himself, indeed, did not rest satisfied with them, but proceeded to verify his hypotheses by the extirpation or destruction of the portions of the cortex which he supposed to be the sensory centres. Experiments by Extirpation or Destruction of Sensory Centres. — The most remarkable result obtained by Ferrier in his first experiments was afibrded by destruction of the angular gyrus. When the angular gyrus of the left hemisphere was destroyed, it was found that the animal was blind on the right eye soon after the operation, but recovered sight com- pletely on the following day. In another case the angular gyri of both hemispheres were destroyed and the animal became completely blind in both eyes. In no case was any motor paralysis observed. The admitted objections to these experiments are that Ferrier did not keep his animals alive a sufficiently long time to ascertain if a return of vision occurred. Goltz found in his experiments that when a considerable portion of the cortex of the brain was removed the animals, although not blind, manifested a peculiar imperfection of vision. The animal operated upon could use his sight in avoiding obstacles, but often failed to recognise his food, and appeared quite indififerent when threatened with the whip. He also found that recovery from this condition was possible, at least to a considerable extent, by means of educational exercises. Munk believes again in the existence of a " visual area," situated in the occipital lobes, and of much larger extent than that of Ferrier. He maintains that removal of this area causes blindness, and that extirpa- tion of small portions of it gives rise to blindness of localised areas of the retina. He believes that there are three visual spheres in the cortex of the occipital lobe corresponding to three visual areas in the retina. The external part of the retina of the left eye is connected with the external part of the cortical visual centre in the left hemisphere, while the internal and central portions of the retina of the right eye are respec- tively connected with the internal and central portions of the visual centre of the opposite or left hemisphere. He also thinks that the upper part of the retina is connected with the front, and the lower part with the posterior aspect of the visual centre of the opposite side. Removal of both visual centres causes, according to this observer, complete 496 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. or absolute blindness. Partial removal of these areas on the other hand gives rise to the visual defect called attention to by Goltz, in which the animal can see and avoid objects, but does not recognise his food as such. This Munk calls psychical blindness (Seelenlahmungen, Seelenblindheit). He finds that after a time the animals recover from psychical blindness, provided the whole visual area be not removed. He thinks that the recovery is due to a process by which there is a deposition of new visual experiences in the rest of the visual area. The physical part of the restoration might probably be spoken of with greater justice as the formation of new structural arrangements in the visual areas. Munk describes an auditory area, which however differs from that of Ferrier, and he regards the whole front part of the brain as forming a large "sensory" area, in which separate sensory centres may be distinguished. Fig. 236. Fig. 236 (After Munk). Upper Surface of the Brain of pie Monkey.— Sensory Areas : A, of the eyes ; B, of the ears ; C, of the sensibility of the lower extremity ; D, Anterior extremity ; E, Head ; F, Ocular muscular apparatus ; G, Region of ears; H, Neck; I, Body. An elaborate paper on the cerebral visual centres was read before the physiological section at the meeting of the British Medical Association, at Cambridge, in August last, by Professors Ferrier and Gerald F. Yeo. Large portions of the brains of monkeys were removed, the operations being conducted antiseptically, so that there was a total absence of encephalitis. The following is an abstract of the chief results obtained : — 1. Removal of both occipital lobes did not cause any recognisable dis- turbance of vision, or other bodily or mental derangement, provided the lesion did not extend beyond the parieto-occipital fissure. 2, Complete destruction of one angular gyrus causes temporary loss of vision of one eye, lasting only a few hours. The restoration of vision is J ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 497 not due to the integrity of the other angular gyrus. If both angular gyri be destroyed simultaneously total blindness ensues in both eyes, but does not last more than three days, although vision may be impaired for months. If the angular gyri be destroyed successively/, several weeks elapsing between the operations, the animal sees quite well with both eyes in a few hours. 3. Simultaneous destruction of the angular gyrus and occipital lobe on one side causes evident loss of vision in both eyes towards the side oppo- site the lesion (hemiopia), but recovery from this condition takes place at the end of a week. 4. Destruction of the left angular gyrus (recovery), and subsequently of the right angular gyrus and occipital lobe, produces left hemiopia, from which the animal recovers in a fortnight. 5. Destruction of both occipital lobes, followed after a time by destruc- tion of the left angular gyrus, causes transient blindness followed by indistinctness of vision of right eye, with subsequent complete recovery. 6. Destruction of both angular gyri and occipital lobes causes total and permanent blindness in both eyes, without any impairment of the other senses or of motor power. 3. Prce-frontal or Ideational Area of the Cortex. Experiments by Stimulation. — Electrical irritation of the prae-frontal region of the cortex in the monkey causes no motor reaction (Ferrier). Experiments by Extirpation. — Complete destruction of the pree-froutal lobes in the monkey causes no paralysis of motion and no sensory dis- turbance, but the character of the animal suffers great deterioration sub- sequently to the operation. " Kemoval or destruction by the cautery of the antero-frontal lobes," says Dr. Ferrier, " is not followed by any definite physiological results. The animals retain their appetites and instincts, and are capable of exhibiting emotional feeling. The sensory faculties — sight, hearing, touch, taste, and smell — remain unimpaired. The powers of voluntary motion are retained in their integrity, and there is little to indicate the presence of such an extensive lesion, or a removal of so large a part of the brain. And yet, notwithstanding this apparent absence of physiological symptoms, I could perceive a very decided alteration in the animal's character and behaviour, though it is difficult to state in precise terms the nature of the change. The animals operated on were selected on account of their intelligent character. After the operation, though they might seem ■ to one who had not compared their present with the past fairly up to the average of monkey intelligence, they had undergone a considerable psychological alteration. Instead of, as before, being actively interested in their surroundings, and curiously prying into all that came within the field of their observation, they remained apathetic or dull, or dozed off to sleep, responding only to the sensations or impres- sions of the moment, or varying their listlessness with restless and purposeless wanderings to and fro. While not actually deprived of GG 498 ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION, intelligence, they had lost to all appearance the faculty of attentive and intelligent obeservation." The conclusions which Dr. Ferrier has drawn from his experiments on animals are fully borne out, as we shall subse- quently see, by the results of diseases and injuries of the pree-frontal lobes in man. The whole evidence shows that, although destruction of these lobes is not followed by decided sensory or motor disturbances, yet that the later evolved (representative and re-representative) cognitions and emotions are seriously impaired. § 688. Localisation of the Mechanisms which regulate the Fundamental and Accessory Actions. We have already seen that the fundamental portions of the convolutions of the motor area of the brain are found near the great longitudinal fissure, while the accessory portions of these convolutions are found in the convo- lutions of the operculum ; and it may therefore be expected that the funda- mental motor actions will be regulated from the former, and the accessory functions from the latter. Several lines of evidence converge in support of this view. The large giant-cells are found in the convolutions near the great longitudinal fissure, while these cells diminish in size as we descend towards the convolutions of the operculum. But we have already seen that the size of the motor ganglion cells of the anterior grey horns of the cord is determined by the size of the muscles whose movements they regulate more than by any other circumstance, and it is very likely that a similar relation exists between the giant-cells of the cortex and the muscles with which they are connected. But the fundamental actions are, as a rule, produced by the contractions of large muscles, such as those of the trunk and lower extremities, and consequently we may expect that they will be regulated by means of the large cells of the central convolutions near the great longitudinal fissure ; while, on the other hand, the accessory actions are produced by small muscles, such as those of the hand, larynx, and face, and we may expect that they will be regulated through the smaller cells of the convolutions of the operculum. Again, the fibres of the pyramidal tract, which are meduUated in a nine months embryo — the fundamental fibres — are connected with the central convolution near the great longitudinal fissure ; while the non-medullated fibres — the accessory fibres of the tract — are connected with the convolutions of the operculum. The fibres which connect the posterior portion of the third frontal convolution with the internal capsule and cruata are not me- duUated before fourteen weeks after birtn (Flechsig). We have already seen that a large proportion of the accessory fibres of the pyramidal tract terminate in the medulla oblongata, and in all probability the majority of them are concerned in regulating the special movements of articulation and facial expression. A glance at Dr. Ferrier's diagrams {Figs. 232 and 233) of the motor centres of the human brain shows that the movements of the trunk and lower extremities are regulated from the central convolutions near the great longitudinal fissure ; that those of the ANATOMICAL AND PHYSIOLOGICAL INTRODUCTION. 499 arma are regulated from the middle of the ascending frontal and parietal convolutions ; and that those of the face, tongue, and hand are regu- lated from the convolutions of the operculum. The facts of development and of experimental physiology, therefore, concur to shovf that the funda- mental actions are regulated from the central convolutions near the great longitudinal fissure, and the accessory functions from the convolutions of the operculum. It must also be remembered that the grey matter at the bottom of the fissures is developed subsequently to that of the summits, and consequently the former represents an organisation which has been super- added to the latter in the course of evolution. But the portion of the cortex of the Island of Reil which adjoins the convolutions of the operculum is the great area in which new structure is superadded to the motor region of the cortex. As the grey matter in the neighbourhood of the anterior perforated space increases in superficial extent, the external aspect of the cortex of the central lobe is thrust upwards and outwards so as to develop the convolutions of the operculum ; and each addition of grey matter to the latter convolutions represents an additional complexity in the pre-existing structure corresponding to an additional complexity of previous muscular adjustments. Each increment which is added to the inferior extremities of the central convolutions by the upward growth of the cortex of the Island of Reil increases the length of the former ; but as their upper ex- tremities are prevented from moving freely upwards by the skull, their lower extremities are thrown into a fold, and consequently the depth of the sulcus which separates the Island of Reil from the convolutions of the operculum may be accepted as an indication of the degree of development of the accessory portion of the motor area of the cortex. § 689. Localisation of the Cortical Centres ofGeTural and Special Sensations. We have seen that in the spinal cord the conducting paths of the common sensations passed directly into the posterior grey horn, through the middle of the fan formed by the fibres of the posterior roots on their entry into the cord ; while, on the other hand, the conducting paths of the special cutaneous sensations are thrust inwards and outwards, so as to occupy positions outside the margins of the posterior horns. A somewhat similar process appears to take place during the development of the cortex in relation to the common and special cutaneous sensations and the special senses. According to the latest experiments of Ferrier and Munk the centre of vision — the most special of all the senses — is situated on the outer convex surface of the occipital lobe in the area of the terminal distribution of the posterior cerebral artery, while the centre of tactile sensation is situated in the hippocampal region, close to the root of the same artery. It is probable that the sensation of pain is too much diffused in the cortex to admit of any definite localisation. Both the auditory centre — the superior temporo-sphenoidal convolution — and the olfactory centre — the subiculum cornu Ammonis — although situated nearer the root of the artery than the visual centre, yet occupy positions 500 ANATOMICAL AND PHYSIOLOGICAL INTEODUCTION. near the terminal distribution of some of the branches of the posterior cerebral artery, and certainly further removed from its root than the centre of tactile sensation. § 690. Localisation of Function in the Proe-frontal Area of the Cortex. If the higher mental operations be carried on in the anterior area of the cortex, this region must contain the plexuses of cells and fibres, which, when excited, become the correlatives of the representative and re- representative cognitions and feelings. No progress has been made In localising the functions of this area of the cortex. It is, however, probable, that the later-acquired emotions and cognitions will be repre- sented in the cortex by the grey matter in the bottom of the fissures, and by the grey matter of the convolutions of the orbital surface which adjoins the anterior perforated space and which are situated close to the root of the anterior cerebral artery. Pathological observation bears out the idea that disease of the cortex of the orbital surface produces much less mental disturbance than disease of the superior convex surface of the pree-frontal area. And this is only what might be expected if the former is developed at a later period than the latter. The convolutions of the orbital surface would then represent the later-acquired cognitions and emotions, and abolition of them would cause less mental disturbance than abolition of those which are earlier acquired but more fundamental. A man, for instance, may live what is regarded as a respectable life when he is destitute of all reverence, and is wholly in- capable of doing an unselfish action, while the only self-restraint he places over his appetites and passions is that which the most calculating selfishness suggests. Yet reverential feeling, unselfishness in action, and self-restraint are the latest acquisitions in the development of the human mind. If, however, a man, instead of being lacking in reverential feeling, becomes openly profane, and instead of not being unselfish he commits deeds of violence in order to deprive others of their rightful property, and if instead of curbing his passions even by a calculating selfishness he gratifies them without shame and regardless of consequences, it is evident that a lower stratum of mental degradation has been reached, and the portion of the cortex now diseased is a more fundamental one, which must have been developed at an earlier period than that which was diseased in the first instance. 501 CHAPTER II. MOEBID ANATOMY AND CLASSIFICATION OF THE DISEASES OF THE ENCEPHALON. (I.)— MORBID ANATOMY OF THE ENCEPHALON. The operation of the law of evolution having been already traced in the construction of the brain, we must now endea- vour to trace the action of the law of dissolution in the breaking down of structure the result of disease. § 691. Histological Morbid Changes. — The histological changes which occur in the tissues of the brain during diseased processes are essentially the same as those which have already been described in the case of the spinal cord (§ 887), and it is, therefore, unnecessary to repeat the description. § 692, Morbid Alterations of the Circulation within the Cranium. — It was first pointed out by the second Monroe that the circulation within the cranium differs from that of other parts of the body. The cranium forms a bony case, capable of resisting the atmospheric pressure, and no substance can be dislodged from it without some equivalent taking its place; while, on the other hand, no substance can be added to the con- tents of the cranium without dislodging an equivalent bulk of some other substance. This opinion was experimentally tested by Kellie, and defended by Abercrombie, Reid, and Watson. Dr. Burrows endeavoured to combat this opinion, but he only showed, what was never denied, that the quantity of blood in the brain could be increased or diminished by various circum- stances. The doctrine of Monroe simply asserts that if the quantity of blood in the cavity of the cranium be increased, 502 MORBID ANATOMY AND CLASSIFICATION some other fluid must be dislodged; while if the quantity of blood be diminished, some other fluid must fill up the vacant space. The quantity of blood in the brain can undoubtedly be increased or diminished, but this can only take place by a corresponding diminution or increase in the quantity of the cerebro-spinal fluid and of the fluid contained in the peri- vascular lymph spaces. When, however, the intracranial pres- sure is rendered still greater, as by extravasation of blood from rupture of a blood-vessel, room is made for the sub- stance superadded to the contents of the cranium by a certain quantity of blood being squeezed out of the intracranial arteries, veins, and sinuses, in addition to the displacement of the cerebro-spinal fluid. The circulation within the cranium is liable to be disordered by occlusion or rupture of one or more of the intracephalic vessels, but the reader is referred to the sections on embolism, thrombosis, and cerebral haemorrhage for detailed descriptions of these processes. Tumours. — The growth of intracranial tumours of all kinds must necessarily be attended by great disturbance of the cere- bral circulation. In order to make room for the increasing bulk of the tumours the cerebro-spinal fluid, as well as the fluid of the perivascular lymph spaces, is first squeezed out, the blood is then compressed from the intracranial blood-vessels, so that the whole brain is rendered anaemic. § 693. Secondary Degenerations. — Long-standing hsemor- rhagic and other diseased foci give rise to various secondary changes not only in the surrounding tissues, but also in distant parts. These changes are of two kinds : firstly, those which involve the entire mass of the brain ; and secondly, those limited to certain tracts of conducting fibres, which are inter- rupted in their course by the hsemorrhage. (1) General Atrophy. —With regard to the former of these kinds, it is found that the brain frequently undergoes, even after an insignificant hsemorrhage, a slow and general atrophy which occasionally aflects both hemispheres. This condition is especially common after extravasations into the cortex. A per- sistent alteration of one hemisphere of the brain may after a time induce atrophy of the opposite hemisphere of the cerebellum. OF THE DISEASES OF THE ENCEPHALON. 503 (2) Systemic Degeneration. — As has been frequently stated, whenever the fibres of the pyramidal tract are injured in any part of their course from their origin in the cortex of the brain down to their termination in the spinal cord, the portions below the seat of injury undergo descending degeneration. A focal lesion, limited to the middle third of the iwsterior segment of the internal capsule {Fig. 237, F), is followed by descending degeneration of the fibres of the middle third of the crasta {Fig. 238, L), and of a portion of the longitudinal fibres of the pons and anterior pyramid of the medulla. In the lower end of the medulla the greater part of the degenerated fibres cross over to the lateral column of the opposite side of the cord {Fig. 239, A), while some of them pass down the column of Tiirck of the same side {Fig. 239, B). The course pursued by the secondary degeneration in the case Fig. 237. Fig. 237 (Charcot). Horizontal Section of the Right Hemisphere parallel with the Fissure of Sylvius. — Nc, Caudate nucleus ; Sa, Anterior segment of the in- ternal capsule ; Nl, Lenticular nucleus ; G, Knee of the internal capsule ; Sp, Posterior segment of the internal capsule ; Co, Optic thalamus ; F, A focal lesion in the middle third of the posterior part of the internal capsule. 504* MORBID ANATOMY AND CLASSIFICATION Fig. 238. F L D Fig. 238 (Charcot). Hoi'izontal Section of the Crura Cerebri in a case of Secondary Degeneration. — T, Tegmentum; F, Crusta of the healthy side; L, Locus niger; D, The degenerated fibres, occupying about the middle third of the crusta ; P, The fibres which undergo secondary degeneration only when the fibres of the anterior segment and the knee of the internal capsule are diseased. Fig. 239. Fig. 239 (Charcot). Transverse Section of the Cervical Region of the Sjyinal Cord, from a case of lesion of the motor area of the cortex of the opposite hemisphere. — A, Degeneration of the pyramidal tract ; B, Degeneration of the direct fibres ; C, Direct cerebellar tract ; D, Intermediate region between the posterior grey horn and the pyramidal tract, the fibres of which do not undergo descending degeneration. OF THE DISEASES OF THE ENCEPHAEON. 505 just described corresponds to that of the fundamental fibres of the pyra- midal tract during their development {Figs. 223 and 224). A case has been described by Brissaud in which, along with extensive recent softening of one hemisphere, an old focus of softening was observed limited exactly to the knee of the internal capsule {Fig. 240, D). A streak of degeneration Fig. 240. Fig. 240 (Brissaud). Recent Softening of the Frontal Lohe, the Island of Eeil, and Middle Third of the Lenticulai' Nucleus. —T), Old iocus of softening occupying the knee of the internal capsule; A, Caiidate nucleus; B, Optic thalamus ; C, Anterior, and E, Posterior division of the internal capsule. was observed lying between the internal and middle thirds of the crusta, being the anterior portion of the area which has already been described as the mixed area of medullated and non-meduUated fibres in a nine months embryo {Fig. 223). According to Brissaud degeneration occurs in the knee of the internal capsule in cases of long-standing aphasia. Another important case has been observed by Brissaud in which an old focus of softening was found in the anterior half of the lenticular nucleus, destroying also the anterior segment of the internal capsule {Fig. 241, F). A streak of degeneration was observed in the internal third of the crusta {Fig. 241, P), but all the fibres of this area were not implicated in the degeneration, a small bundle of the innermost fibres remaining normal. The degenerated fibres in this case corresponded very nearly to those which we have described as the accessory fibres of the tract. Degeneration of the internal tract of the crusta, according to Brissaud, appears to be always connected with intellectual disorders. 506 :^rOEBED ANATOIirT AND CLASSIFICATION The iollowing bundles of fibres may, therefore, be distingxiished. in the internal capsule (Brissaud) : — (1) A. posterior or sensory fascicuhis (occupying the external third of the crusta), which is never the seat of secondary degeneration. (2) A middle fasciculus (occupying the middle third of the crusta), which is the usual seat of secondary degeneration. (3) A geniculate fasciculus (occupying the point of union of the middle and internal thirds of the crusta), which has erroneously been regarded as incapable of degeneration. This fasciculus contaias fibres which ax'e dis- tributed to the bulbar centres, and are. concerned in the production of the voluntary movements of the face and tongue. (4) An anterior fasciculus (occupying the internal third of the crusta), degeneration of which appears only to be associated with intellectual disorders. Fig. 241. Fig. 241 (Brissaud). — A, Caudate nucleus ; B, Optic thalamus ,* C, Posterior and healthy part of the lenticular nucleus ; D, Posterior segment of the internal capsule ; E, Lesion of the anterior segment of the capsule ; F, Cyst pre- senting the form of the lenticular nucleus; P, Degeneration of the internal fibres of the crusta. OF THE DISEASES OF THE ENCEPHALOX. 507 § 694. Congenital Malformations oftlie Shull and Brain. (1) Anencephalia. — In this condition the upper portion of the sloill and brain is entirely absent. This condition is sometimes associated vrith amyelia, a condition in which the vertebral column remains xmclosed, and the spinal cord is wanting (Forster). (2) Hemicrania. — The anterior portion of the skull is absent and the brain deficient. (3) ffemicepho.Ua. — The lateral half of the brain and skull is deficient. (4) Notencephalus. — The upper part of the skull is deficient, and the vertebral column is not entirely closed in, while the brain develops in the vertebral canal instead of the skulL (5) Hydrencephalocele. — In this condition the bones of the skull are deficient, an opening being left, generally at one of the fontaneUes, through which a soft, fluctuating ttunoiu" projects. The tumour contains fluid, and can generally be emptied by steady pressure. The walls of the tumour consist of the soft coverings of the skull, and the distended membranes of the brain. The tumour communicates with the general ventricular cavity of the brain. (6) EncephaloceU. — The bones of the skull are again deficient at some part in this condition, but through the opening formed a portion of the brain itself projects, forming a broad, flat, solid tumour. The tumour &«quently occupies the forehead, orbit, or side of the nose. § 695. The Low of Dissolution. — Although the law of disso- lution is probably destined at some future time to throw more light on the morbid anatomy of the brain than on that of any other organ of the body, yet it must be admitted that up to the present very little progress has been made in this direction. The law has been applied by Dr. Hughlings-Jackson with much ingenuity and success to the interpretation of disordered cerebral functions, but it has yet to be applied to the eluci- dation of morbid cerebral structures. The histological elements of the brain doubtless conform to this law in their degene- rations in a manner similar to that already described with regard to the histological elements of the spinal cord. And even when the disease is diffused in the neuroglia the small cells and thin fibres of the accessory portion of the brain must suffCT injury more readily than the large cells and thick fibres of the fundamental portion. This a priori necessity has not, however, been verified as yet by a posteriori observations. Even in such a coarse lesion as that caused by occlusion of one of the cerebral arteries — sav the inferior frontal branch of the 508 MORBID ANATOMY AND CLASSIFICATION left Sylvian artery — the operation of this Jaw may probably be traced. If, as we have already endeavoured to prove, the later- formed cells and fibres of Broca's convolution lie near the root of this artery, while the earlier-formed cells and fibres are thrust upwards and forwards towards the terminal twigs of the vessel, it is manifest that the earlier is in a much more favour- able position than the later developed portion to obtain nourish- ment from the neighbouring vascular territories. But this con- clusion, although there is much probability in its favour, has not yet been confirmed by careful dissection. These brief and imperfect remarks are all that we feel justified in making, in the present state of our knowledge, with regard to the applicability of the law of dissolution to the structural altera- tions produced by disease in the brain. (II.) -CLASSIFICATION OF THE DISEASES OF THE ENCEPHALON. It is impossible to give a full and scientific classification of the diseases of the encephalon, inasmuch as a large propor- tion of them are beyond the scope of this work. It is not our intention to enter upon the discussion of the wide class of diseases of the brain comprised under the general term insanity, and yet no classification of the diseases of the encephalon can be considered satisfactory which does not comprise them. In endeavouring to classify the diseases which remain, we shall proceed on the principle of considering first those which give rise to the fewest, and leaving to the last those that occasion the most numerous and complicated symptoms. Now as disease of the membranes can hardly ever exist without producing secondary disease over a large area of the surface of the brain, the symptoms characterising the former may be expected to be on the whole more complicated than those of the latter, and consequently the diseases of the encephalon will be considered prior to those of the membranes. Of the diseases of the encephalon, the lesions which give rise to the least complicated symptoms are the focal, and those which give rise to the most complicated symptoms are the diffused lesions. It is known that a focal lesion, as a tumour, may by increasing the intra- cranial pressure and in other ways give rise to diffused effects, OF THE DISEASES OF THE ENCEPHALON. 509 and that a diffused disease like encephalitis may by terminating in abscess occasion local symptoms. The division into focal and diffused lesions is, therefore, not a scientific but a practical dis- tinction, and must be judged entirely from a practical stand- point. The symptoms caused by focal diseases depend partly upon the nature and partly upon the locality of the lesion. Cerebral haemorrhage, for instance, occasions a grouping of symptoms which enables the affection to be readily distinguished from the symptoms produced by the slow growth of an intra- cranial tumour ; yet the symptoms caused by destruction of a certain portion of the internal capsule, for instance, is the same whether the injury be caused by haemorrhage or by the growth of a tumour. The focal diseases, therefore, admit of considera- tion under two aspects: (I.) according to the symptoms common to the pathological state in general; and (II.), according to the special functions of the region affected. With these few remarks the following classification may be allowed to explain itself : — A. Diseases of the Encephalon. I. Focal diseases. (i.) General consideration of focal diseases, according to the nature of the lesion. 1. Occlusion of intracranial vessels. 2. Intracranial haemorrhage. 3. Intracranial tumours. (ii.) Special consideration of focal diseases, according to the localisation of the lesion. 1. Affections of peduncular fibres and internal capsule. a. Affections of the pyramidal tract. (i.) Hemiplegia, (ii.) Hemispasm. b. Affections of the sensory peduncular fibres and optic radiations of Gratiolet. (i.) Hemiansesthesia. 2. Lesions of the cortex of the brain and of the subjacent portion of the centrum ovale. a. Lesions in the area of the middle cerebral artery, (i.) Unilateral convulsions, and mouosj)asms. (ii.) Monoplegise. (iii.) Cortical affections of speech. 510 CLASSIFICATION OF DISEASES OF THE ENCEPHALON. b. Lesions in the area of the posterior cerebral artery. c. Lesions in the area of the anterior cerebral artery. 3. Lesions in the basal ganglia, external capsule, claustnim, and base of the brain. 4. Lesions localised in the structures situated below the tentorium. a. Lesions in the pons and peduncles of the cerebrum. h. Lesions in the peduncles of the cerebellum. c. Lesions in the cerebellum. II. Diffused diseases of the encephalon. (l.) Aneemia and hypersemia of the brain, (ii.) Atrophy and hypertrophy of the brain. (ill.) Shock, and concussion of the brain, (iv.) Encephalitis. 1. General encephahtis. 2. Partial encephahtis. a. Acute encephalitis, complicating affections of the petrous portion of the temporal and other bones of the skull. h. Acute pysemic encephalitis. c. Encephalitis secondary to other cerebral lesions. d. Chronic abscess of the brain. B. Diseases of the Membranes of the Brain. I. Diseases of the dara mater. (i.) External pachymeningitis, (il.) Internal pachymeningitis. II. Diseases of the pia mater. Acute inflammation of the pia mater. 1. Leptomeningitis Infantum. 2. Tubercular meningitis. 3. Meningitis of the base of the brain. 4. Meningitis of the convexity of the brain. 5. Metastatic meningitis. 6. Traumatic meningitis. 511 CHAPTEE III. (I.) GENERAL CONSIDERATION OF FOCAL DISEASES, ACCORDING TO THE NATURE OF THE LESION. 1. OCCLUSION OF THE INTRACRANIAL VESSELS. The arteries, veins, sinuses, and capillaries of the brain are liable to become occluded, a circumstance which gives rise to various pathological changes. The occluding body may be formed on the spot, constituting thrombosis ; or may be carried from distant parts, constituting embolism. (a) Occlusion of the Cerebral Arteries. § 696. Etiology. — Emboli consist of fibrinous masses washed away from the left cavities of the heart, the aortic and mitral valves, the arch of the aorta, and occasionally from the pulmonary veins. In cases of carcinoma of the lungs, a cancerous mass may possibly be carried from the pulmonary veins and pass into the cerebral vessels. Arterial thrombosis is determined partly by general causes tending to diminish the force of the heart's action and to alter the quality of the blood, and in part by local degenerations of the coats of the vessels themselves. During convalescence from acute diseases and other exhausting processes, the heart is weak, and the blood becomes so altered in quality that it is specially prone to coagulate. This process is, of course, much favoured if the heart have undergone dilatation without proportionate hypertrophy. The local causes of thrombosis are alterations of the walls of the arteries, whereby their lining membrane is roughened and their calibre is narrowed. The coagulation of fibrine is favoured by changes in the walls and internal surface of the vessel, such as those due to atheromatous and calcareous 512 FOCAL DISEASES, ACCORDING TO degenerations. Thrombosis is particularly liable to occur when general causes and local degeneration act together. Thrombosis may take place in any of the arteries at the base of the brain, or in several of them at the same time. A thrombus not unfrequently forms in one of the internal carotid arteries, and the clot then often extends into the middle and anterior cerebral arteries of the same side, and sometimes even into the posterior communicating and the posterior cerebral artery. Of the predisposing causes of cerebral thrombosis age is probably the most important. Thrombosis occurs more fre- quently in advanced age, owing to the degenerative changes in the vessels, although it may occur at all ages. Embolism, on the other hand, is met with in relatively young persons, although it may also occur in persons of advanced years. § 697. Sympto'ms. — The symptoms which characterise the later stages of thrombosis and embolism are the same, but those of the early period differ considerably. The symptoms of embolism are very sudden in their onset, and are not preceded by any premonitory signs. The patient is suddenly attacked with dizziness, utters an involuntary cry, or complains momentarily of headache, and then almost imme- diately loses consciousness. The symptoms occasioned by embolism of a cerebral artery are in their general characters and mode of onset almost identical with those of cerebral bsemorrhage, but the unconsciousness caused by embolism is, as a rule, more transient than that produced by hgemorrhage. In many cases there is no coma, but only some dizziness or slight confusion of mind for a minute or two, along with the sudden advent of paralysis. The attack is sometimes ushered in by epileptiform convulsions, which may sometimes be general like an ordinary epileptic attack, but are at other times limited to one -half of the body, to one extremity, or one-half of the face. When general convulsions are present they occur simul- taneously with the loss of consciousness, and are followed by paralysis immediately, while unilateral and partial convulsions may recur repeatedly before paralysis is fully established. In some cases the attack is accompanied by vomiting, and Hammond reports a case in which active delirium, and another in which THE NATURE OF THE LESION. 513 hallucinations and delusions were present for some hours after a sudden attack of hemiplegia. The presence of disease of the aortic and mitral valves in Hammond's cases rendered the diagnosis of embolism very probable. In many cases sudden speechlessness, a condition which will be subsequently described as aphasia, constitutes the only symptom of the affection, and in these cases the symptom may disappear in a few days when collateral circulation is estab- lished. As a rule, however, the aphasia is associated with right-sided hemiplegia, which possesses the same general characters as that which results from haemorrhage into the lenticular nucleus and neighbouring parts. The right side is more frequently affected with paralysis than the left, owing to the greater liability of the left middle cerebral artery to be affected by embolism. The state of the pupils during the onset of the attack has been variously described, and it probably varies in different cases. Erlenmeyer states that the pupils remain sensitive, being neither contracted nor dilated, while Hammond has found dilatation, contraction, or irregularity. The symptoms of thrombosis are, as a rule, more gradual in their development than those of embolus. The more usual premonitory symptoms of thrombosis of a cerebral vessel con- sist of headache, which may be diffused through the entire head or referred to the neighbourhood of the morbid process (Hammond), dizziness, and a sense of general confusion. The patient may complain of numbness, coldness, or formication in one extremity or throughout the distribution of one nerve or in the entire half of the body. At times there may be considerable mental disturbances, and failure of memory is often a marked symptom. Motor disturbances are usually of the nature of more or less extensive paresis, but occasionally the loss of motor power is preceded by slight convulsive move- ments. Paralysis may occasionally supervene suddenly, but, as a rule, its development is slow and gradual, its progress being marked by successive remissions and exacerbations. This mode of development appears to be due to the fact that thrombosis has a tendency to extend backwards and to implicate more and more of the arterial branch, in whose ultimate twigs the process may have first begun. The duration of the prodromal stage HH 514 FOCAL DISEASES, ACCORDING TO may vary from a few hours to several months, and occasionally apoplectic symptoms may come on suddenly, as in embolism. When once the vessel has become completely occluded, the further progress of thrombosis is like that of embolism in the same situation. When softening occurs the temperature, according to Bourn e- ville, rises on the second or third day after the attack, and in two or three days may be as high as 40° C. (104° F.). In a few days longer the temperature sinks rapidly, its decline being more rapid than that which takes place after the period of re- action in cases of haemorrhage. When once softening has become thoroughly established the symptoms are those which result from localised cerebral disease generally, and indeed the symptoms of softening and of haemorrhage when regarded as localised diseases are often identical. Contractures of the paralysed limbs are not so common in cases of occlusion of vessels as in cases of haemorrhage, but they occur sufficiently often to make their presence or absence destitute of diagnostic significance. The sensory, trophic, and vaso-motor disturbances, as well as the affections of the special senses, with the exception of vision, are the same as those which occur in connection with cerebral haemorrhages. In some cases of embolism the ophthal- mic artery has become occluded, giving rise to sudden amaurosis. On ophthalmoscopic examination the arteries of the retina are seen to be empty ; they appear like fine threads, but still re- tain their red colour. The veins are not much diminished in size, and are filled with dark blood. The retina presents a greyish or white opacity which is most marked around the macula lutea, but the fovea centralis remains of a bright red colour, forming a marked contrast with the pallor of the sur- rounding portion of the retina. Various disturbances of the mental faculties may result from embolic softening. Probably the most interesting of these is aphasia, which results from embolism of the middle cerebral artery generally of the left side, but this condition will be dis- cussed at greater length in a future chapter. In some cases of occlusion of cerebral arteries the symptoms begin to improve at an early period, and the patient may THE NATURE OF THE LESION. 515 ultimately recover completely. In these cases it is evident that the collateral circulation has been established before softening has commenced. In other cases the patient, after partial or complete recovery, is attacked again with embolism, and there may be a second recovery. In some cases of throm- bosis the first symptoms may be of moderate severity, and may afterwards become by sudden accessions more and more severe. In some few cases death may follow immediately, but as a rule it is not so sudden as in haemorrhage. Diseases of the mitral or aortic valves, aortic aneurism, ulcerative endocarditis, and inflammatory or syphilitic affec- tions of the muscular substance of the heart are the compli- cations usually met with. In cases of thrombosis evidences of degeneration of the vascular system can usually be detected in the radial and other arteries. Important symptoms may arise from embolism in the spleen, the kidneys, and the arteries of the extremities. § 698. Diagnosis. — The problem of diagnosis is to distin- guish cerebral embolism, thrombosis, and haemorrhage from one another. This must be done, not so much by means of the cerebral as of the associated symptoms. When sudden hemiplegia occurs in a young or middle-aged person who is suffering from valvular disease of the heart or aneurism, the symptoms are in all probability due to embolism. The probability of embolism of a cerebral artery is rendered still greater if there be a history of previous seizures in the brain or other organs. Kight-sided hemiplegia, with aphasia, results more frequently from embolism of the left middle cerebral artery than from any other cause, and consequently in such cases the presumption is always in favour of occlusion of the vessel rather than haemorrhage, provided there be the necessary conditions for its occurrence. There are no absolute means of distinguishing between haemorrhage and thrombosis, and it is needless to discuss the various diagnostic signs which have from time to time been proposed. § 699. Morbid Anatomy. — Embolism affects certain vessels with special frequency. The mode of origin of the left carotid 516 FOCAL DISEASES, ACCORDING TO directly from the arch of the aorta, and the angle at which it leaves the arch, very much favour emboli being carried into it. These emboli usually pass the circle of Willis and make their way into the left middle cerebral artery, which is the direct continuation of the internal carotid, and, consequently, this artery is more frequently occluded by an embolus than any other vessel of the brain. Thrombosis does not appear to have a special preference for any one artery. The middle and posterior cerebral, and verte- bral arteries are equally liable to be occluded by thrombosis. When one of the cerebral arteries — the left middle cerebral artery, for example — is obstructed close to the circle of Willis, the circulation through the nutrient arteries supplied by it to the basal ganglia is arrested, and as these are terminal arteries rapid softening occurs. When one of the vessels of the brain is obstructed on the cardiac side of the circle of Willis, the free anastomosis of the latter re-establishes the circulation so quickly that no pathological changes occur in the brain. If, again, the embolus be carried forwards past the basal portion to the arterial system of the cortex, it is quite possible that the free anasto- mosis of the latter may prevent decided pathological changes from taking place. In many cases, however, a certain amount of softening does occur under such circumstances, because the anastomosis is not always so free as to compensate for the blocking up of a large branch of the artery. When the embolus is lodged in one of the terminal arteries of the basal arterial system softening always occurs, owing to the absence of anastomosis with neighbouring arteries. The first effect produced by occlusion of a terminal artery is oedema of the part supplied by it. The venules and arterioles of the part are imper- fectly nourished so that their walls dilate and frequently rupture, giving rise to hypersemia attended by cedematous swelling and haemorrhage. The tissues, not being supplied with nourishment, break down and undergo softening. When the softened tissues become mixed with extravasated blo(^d, they give rise to red softening. The hypereemia and hemorrhage may fail to occur, and then simple necrobiosis results from the occlusion of the vessel, giving rise to a softened mass of a yellowish- white or white colour. These changes generally begin in the course of the second twenty- four hours after the obstruction has occurred, although cases are reported in which the consistence of the brain tissue was normal after the lapse of two days. THE NATURE OF THE LESION. 517 Microscopic examination reveals the presence of a large number of reel blood corpuscles, which is the only abnormal appearance observed during the first twenty-four hours. At a later period the nerve elements undergo gradual degeneration. The most prominent microscopic pecu- liarity consists of granular corpuscles, which are probably derived from degeneration of neuroglia and ganglion cells of the grey substance, and various other sources. Experi7nental Investigations. — The first experimental researches with respect to the embolic process was undertaken by Virchow, and great additional light has been thrown upon the subject by the important ex- perimental and microscopic investigations of Cohnheim. Panum studied experimentally the results of occlusion of cerebral vessels with the view of determining the manner in which death is caused. B. Cohn investigated experimentally various clinical and anatomical points ; Feltz studied the results of capillary embolism ; while Prevost and Ootard made a series of experiments with the view of determining the relation of occlusion of cerebral vessels to softening. § 700. Morbid Physiology. — The most difficult problem to solve with respect to the morbid physiology of the affection is how occlusion of only one of the cerebral arteries produces loss of consciousness. Brown-Sequard has recently dwelt upon the fact that local lesions exert an influence over remote parts of the nervous system, and the sudden arrest in the circulation in one of the arteries of the brain is likely to produce widely- spread effects. Heubner and Duret have shown that although the abundant anastomoses between the arteries of the cortex after a time establish a collateral circulation, yet at the moment of obstruction great disturbances of the circulation and marked changes in pressure may occur in and around the implicated region. We have already seen that sudden depriva- tion of nourishment increases the irritability of nerve fibres, and it is probable that the abrupt arrest of the arterial circu- lation induces a powerful outgoing discharge from the cortex. That this occurs in certain cases is undoubted, inasmuch as the onset of the attack is marked by general convulsions. A powerful discharge of this kind would be followed by exhaustion, and temporary loss of function, or in other words the attack would be characterised by loss of consciousness. In those cases in which there is an absence of convulsions the cortical dis- charges may be supposed to neutralise one another in the nervous system without producing their usual visible effects. 518 FOCAL DISEASES, ACCOEDING TO § 701. Prognosis. — Both embolism and thrombosis are always serious affectioas. When embolism occurs in a young person recovery from the immediate effects may be rapid and complete, but the underlying affection to which the attack was due will still be present and may cause a similar attack in the future or give rise to other grave symptoms. Thrombosis is usually associated with advanced age, enfeeblement of the heart's action, and degeneration of arteries, and during the attack there is great danger, however slight the symptoms ma}^ at first appear, that the occlusion will become more and more extensive. § 702. Treatment. — Prophylactic measures can only be adopted when premonitory symptoms are present for a long time in connection with a slowly-forming thrombosis. In such cases the heart should, according to theory, be stimulated by digitalis, ammonia,, and alcoholic stimulants ; but since it is impossible to diagnose this condition during life from hsemorrhage, it will be better to be content with adopting the same treatment as that recommended for hsemorrhage. During the stage of coma also the same means should be used as in hsemorrhage. (6) Thrombosis of the Cerebral Sinuses. .§ 703. History. — Special attention was first directed to the subject of thrombosis of the cerebral sinuses by the observations of Tonnele. Many valuable clinical observations with regard to the disease were made by Puchelt, and the attention of Lebert was also directed to it. The treatises of Von Dusch, B. Cohn, and of Lancereaux helped greatly to extend and to systematise our knowledge with respect to this thrombosis ; and in more recent times our knowledge has been further increased by the labours of Gerhardt, Griesinger, Corazza, Heubner, and Hugnenin. § 704. Etiology. — Thrombosis of the sinuses may be divided into two groups : the first comprising the cases which arise in the absence of any affection of the walls of the veins, and the second those which originate from phlebitis. The cases of the first group arise in conditions oi 'marasmus , in which the quality of the blood is altered and the circulation enfeebled. Under such circumstances coagulation of the blood is specially prone to occur in the sinuses, inasmuch as they are THE NATURE OF THE LESION. 519 rigid tubes and incapable of collapsing ; they are also destitute of muscular walls, and are traversed by bands of connective tissue. Thrombosis of the sinuses from marasmus is particularly apt to occur in children, especially during the first six months of life, when they are liable to suffer from collapse induced by severe diarrhoea. It also occurs in adults, in consequence of profuse suppuration, cancer, senile marasmus, and other con- ditions of debility. This form of thrombosis occurs wdth special frequency in the longitudinal and lateral sinuses. Obstruc- tion to the return of the venous blood towards the heart increases the liability to the formation of thrombosis of the sinuses, but it is not likely that venous stasis can give rise to it in the absence of other favouring conditions. The second group of thromboses is caused by inflammation of the sinuses, the result generally, probably always, of disease or injury of the cranial bones. Caries of the petrous portion of the temporal bone is by far the most common cause of inflammation of the sinuses ; the lateral and petrosal sinuses, which lie in the vicinity of the temporal bone, are then particularly liable to be affected, although the process may implicate the circular and cavernous sinuses as well as the upper part of the internal jugular vein. In most cases a real phlebitis is induced, followed by the formation of purulent thrombi. Thrombosis of the sinuses also frequently follows blows on the head, or inflammatory conditions of the scalp and cranial bones. Erysipelas of the head and face, and furunculus of the face, especially of the upper lip and fore- head, not unfrequently give rise to thrombosis of the sinuses. Cohn observed a case in which suppurative phlebitis of the cavernous sinuses occurred in connection with purulent inflam- mation of the deep muscles of the neck. § 705. Symptoms. — The symptoms of thrombosis of the cerebral sinuses are generally marked by complicating diseases, so that it is rarely possible to diagnose the affection during life. The symptoms also vary greatly, both according to the seat of the occlusion and according as the thrombosis is or is not the result of phlebitis. 520 FOCAL DISEASES, ACCORDING TO Thrombosis of the sinuses in children almost always arises during the marasmus, caused by exhausting diarrhoea, and the symptoms produced are the same as those of cerebral anaemia, being such as Dr. Marshall Hall described under the name of hydrencephaloid disease. In addition to the collapse, somno- lence, and coma of pure cerebral anaemia, motor disorders, as convulsions or paralysis, are generally present. Rigidity of the muscles of the neck, sometimes also of those of the back and even of the limbs, occasionally nystagmus, strabismus, ptosis, and paresis of the facial muscles have been observed. Thrombosis of the sinuses resulting from marasmus in adults gives rise to very various and indefinite symptoms, and at times a slight degree of apathy and general depression are the only symptoms observed. The patient at the outset may complain of headache, nausea, and vomiting, but these soon give place to coma, while in a few cases loss of consciousness may be pre- ceded by delirium, which may assume a maniacal character. The condition of the pupils is variable. Motor disturbances are usually present, the most usual being strabismus, trismus, contractures which may involve one-half of the body, or both legs and both arms, tremors, and epileptiform convulsions, either limited to one or involving the four extremi- ties. The motor disorders may assume the form of paresis or paralysis, which may be limited to the facial nerve or to the motor oculi, or may involve one-half or both sides of the body. At other times both paralysis and convulsions may be asso- ciated, one extremity being the seat of contracture and the other of paralysis. These symptoms may, however, be present in cases of cerebral ansemia or of venous hypersemia of the brain. A valuable sign of the disease is sometimes afforded by swelling of the veins outside the skull which are in commu- nication with the obstructed sinus. The superior longitudinal sinus, for instance, communicates directly with the veins of the nasal cavities and with those on the upper surface of the skull. The occurrence of epistaxis, therefore, favours the idea of obstruction of this sinus, and in children the presence of distended vessels running to the anterior fontanelle from the neighbourhood of the temples and ears on both sides of the THE NATURE OF THE LESION. 521 head also favours the same view. Cyanosis of the face limited to the part supplied by the anterior facial veins is also, according to Gerhardt, of diagnostic significance. The lateral sinus communicates with a small vein which traverses the mastoid process, and in thrombosis of the sinus localised oedema behind the ear may make its appearance. This sign is occasionally valuable, but is rarely met with. Simultaneous occlusion of both lateral sinuses gives rise to the same symptoms as occlusion of the superior longitudinal sinus. The cavernous sinus communicates with the ophthalmic veins, and in thrombosis of this sinus venous hypersemia of the fundus oculi has been observed, as well as oedema of the eye- lids and conjunctiva and prominence of the eyeballs, due to congestion of the retrobulbar veins and of the frontal vein. Paralysis of the motor nerves of the eye, trigeminal neuralgia, and neuroparalytic ophthalmia may also be present, owing to the disturbance in the nutrition of the nerves which pass along the side of the cavernous sinus. In thrombosis of the sinuses in infants the fontanelle is depressed, and at times the edges of the bones pushed one over the other ; but during the progress of the disease the fontanelle may again become tense and prominent, and the cranial bones pressed apart (Gerhardt). This increase of the contents of the skull is caused either by effusion of serum from the tense veins giving rise to a species of hydrocephalus or to extensive meningeal or intra- cerebral hemorrhage resulting from throm- bosis of the sinuses. The phlehitic variety, as already remarked, is generally caused by otitis interna or injuries to the head. These affec- tions also give rise to meningitis and cerebral abscesses as well as to purulent thrombosis, and inasmuch as these patho- logical conditions are frequently combined, it is very difficult to distinguish clinically between them. In a few reported cases, however, suppurative thrombosis was alone present uncomplicated by meningitis or by lesions of the cerebral sub- stance. The affection sometimes pursues a latent course, and is only discovered after death. The symptoms are usually similar to those observed in cases of septicaemia with specially prominent cerebral symptoms. The attack frequently begins 522 FOCAL DISEASES, ACCORDING TO with chilliness, which generally recurs repeatedly during the course of the disease, and the patient has a characteristic typhoid look, with dry tongue, loss of appetite, and mental confusion. After a time the patient falls into a somnolent condition, which gives place to complete coma, terminating in death. Mild delirium is present in a few cases, and more rarely the delirium assumes an active form. Suppurative thrombosis is frequently associated with motor and sensory disturbances caused by the accompanying menin- gitis. These consist of pain in the head, hyperalgesia, paresis, paralysis, and convulsions. § 706. Diagnosis. — When a patient, suffering from caries of the internal ear, furunculus in the face, or who has received an injury to the head, develops symptoms like those of pyaemia, with marked disturbance of the cerebral functions, purulent thrombosis of the sinuses may be suspected. The diagnosis will be further corroborated by the disturbances of the circu- lation, which have already been described from the thrombosis. § 707. Course and Prognosis. — The duration of the disease is difficult to determine, and it may probably extend occasionally over several weeks, although usually terminating in a much shorter time. The prognosis is very unfavourable, but recovery is said, occasionally to take place (Sddillot, Lebert, and Griesinger). § 708. Morbid Anatomy. — Any sinus may become the seat of thrombosis, but some of them are much more liable to be affected than others. The superior longitudinal sinus is the one which is usually implicated in cases of thrombosis from marasmus, and the sinuses in the neighbourhood of the petrous bone in the phlebitic variety. The veins which empty them- selves into the sinuses become enlarged and gorged with blood, and are often filled with thrombotic masses, so that they look like large earthworms when lying on the surface of the brain. Ruptures of the vessels not unfrequently occur, causing meningeal haemorrhage, but sometimes consists only of small hsemorrhagic spots, while at other times may amount to pro- THE NATURE OF THE LESION. 523 fuse hsemorrhage. The cortex of the brain is also frequently the seat of capillary haemorrhages, and Lancereux has described small spots of softening. The phlebitic variety is frequently accompanied by meningitis, caused by the primary lesion. § 709. Treatment. — No treatment has hitherto been found of any avail. (c) Occlusion of the Cerebral Capillaries. § 710. Experimental investigations have shown that marked disturbances of the cerebral functions may be caused by occlusion of the cerebral capillaries, and clinical records also point to the same conclusion. § 711. Etiology. — In severe cases of malarial and intermit- tent fever the cerebral capillaries are liable to be obstructed by dark masses, a condition which has been called pigment em- bolism. The cerebral capillaries may also be obstructed by drops of fat. The fat is usually swept into the blood current by the breaking up of atheromatous formations in the interior of the larger blood-vessels. In cases of injury to bone the fatty tissue of the marrow may be carried into the blood-vessels, giving rise to emboli in the lungs and possibly in the brain. Chorea has been supposed to be due to capillary embolism, but the subject will be subsequently discussed. The cerebral capillaries are said to be occluded by lime becoming deposited in their walls, a process named by Virchow lime metastasis. Some disease of bone is usually associated with this condition, and Virchow thinks that the lime is first absorbed from the diseased bone, and afterwards deposited in the vessels. § 712. Symptoms. — The experiments of Feltz, and of Provost and Cotard show that extensive embolism of very fine particles may rapidly induce death in animals by causing diffuse ansemia of the brain. Nothing analogous to this is known to take place in diseased conditions. If the embolic masses are few the symptoms which they give rise to are so slight as not to be recognisable during life. Such is known to be the case in certain instances of fat embolism. In other cases a considerable 524 FOCAL DISEASES. territory of the brain may be suddenly deprived of its nutriment, and apoplectic symptoms may then be produced, followed by the usual symptoms of a localised cerebral disease. The symptoms, however, are usually such as arise from diffused cerebral disease, the more common of them being dizziness, headache, nausea, trembling, and weakness in the extremities, and mental disturbance, as marked loss of memory and other signs of mental decay. § 713. Morbid Anatomy. — Capillary occlusions are, of course, only to be detected with the microscope. Delacour says that in cases of lime metastasis a resistance is felt to the knife in cutting through the brain, and rough prominences may be felt on the surface with the finger. The nature of the secondary changes in the brain varies according to the number of the vessels obstructed, and it is only when a large number are occluded that disturbance of the circulation will not be compensated, structural changes then occurring analogous to those following obstruction of the large arteries. Experimental investigation has shown that the first effect of the occlusion is to cause ana3mia, and in the further progress of the affection the various stages of necrobiosis may supervene, ending in complete softening. The centres of softening are often of small size, but several are usually present. § 714. The course and prognosis depend upon the extent and nature of the occlusion. Isolated capillary embolisms are of no significance ; but if they are numerous the resulting dis- turbances are in every respect similar to the corresponding secondary effects of the occlusion of the larger arteries. § 715. Treatment. — The treatment must be conducted on general principles. 525 CHAPTER IV. (I.) GENERAL CONSIDERATION OF FOCAL DISEASES, ACCORDING TO THE NATURE OF THE LESION (Continued). I 2. INTRACRANIAL HEMORRHAGE. Intracranial hsemorrhage may be divided into {a) cerebral, and (6) meningeal hsemorrhage. {a) Cerebral Haimorrhage. § 716. Definition. — By cerebral hsemorrhage is here meant an extravasation of blood into the substance of the encephalon or into the ventricles of the brain. § 717. Histo7-y. — Hsemorrhage into the substance of the encephalon is frequently termed apoplexy. The word iiroTrAijao-w means " I strike down," and a j)erson who had suddenly fallen down insensible was said to be in a condition of iTroTrAij^ta. It was pointed out by Wepfer that this condition was frequently caused by cerebral hsemorrhage, and after a time the name of the group of symptoms which signified sudden iinconsciousness was transferred to the anatomical condition which was the most frequent cause of that occurrence. The process did not stop here ; during the coiu-se of investigation it was seen that hsemorrhage into the substance of other organs was not uncommon, and after a time the meaning of the term was extended so as to include these haemorrhages also. The term therefore having come to signify conditions so different, it will be well to avoid its use as much as possible. § 718. Etiology. — The circumstances which predispose to cerebral hsemorrhage are — (1) Disease of the vessels, (2) In- crease of the arterial tension, (3) Disease of the tissues surrounding the vessels, and (4) Certain diseases of the blood itself. 526 FOCAL DISEASES, ACCORDING TO (1) Disease of the Vessels. — The great majority of massive haemorrhages into the substance of the brain are due to fatty degeneration of branches of the Sylvian artery, which pass through the anterior perforated space to reach the corpus striatum. Fatty degeneration of arteries may be primary or secondary. Primary fatty degeneration is a passive process, not being preceded by any increased nutritive activity of the affected parts, but the secondary form of the process is preceded by an inflammatory cellular infiltration of the sub- endothelial connective tissue of the vessels, and constitutes atheroma. It was formerly believed that when the arteries at the base of the brain were found in a condition of atheromatous degeneration the existence of a similar condition of the vessels in the interior of the brain might be inferred, and that intracerebral haemorrhages might in most instances be attributed to the brittleness of the vessels. The behef is now growing that the influence of atheromatous disease in the causation of cerebral haemorrhage is indirect rather than direct. Atheroma of the vessels may occasionally lead to aneurisms of the larger vessels at the base of the brain, but they are not often the cause of hsemorrhage. Besides, rupture of an aneurism of one of the larger vessels would give rise to haemorrhage between the meninges, and not into the substance of the brain. Atheromatous degeneration may, however, cause haemorrhage indirectly by rendering the walls of the larger vessels rigid, so that the pulse wave reaches the arterioles without being modified by the normal elasticity of the arteries. By far the most frequent cause of intracerebral haemorrhage is that condition of the arterioles which has been described by Charcot and Bouchard as miliary aneurisms. These aneurisms are situated on the arterioles, are of a reddish colour, and vary in size from that of a millet- seed to a pin's head. Sometimes a few only are found in the vicinity of the ruptm-ed vessel, while at other times they are scattered in large numbers throughout the whole brain. The parts of the brain in which they are situated, taken in the order of their decreasing frequency, are the lenticular nucleus, the optic thalami, the pons, the convolvitions, the caudate nucleus, the cerebellum, the medulla oblongata, the middle peduncles of the cerebellum, and the centrum ovale. Mihary aneurisms occur rarely before the fortieth year, but are found with increasing frequency after that age. They result, according to Charcot and Bouchard, from a kind of arterial sclerosis of the nature of a chronic periarteritis. This alteration consists in multipKcation of the nuclei of the lymph-sheaths and adventitia, a process which is generally accompanied by atroj)hy of the muscular coat. When atrophy of the latter occurs without a compensatory thickening of the adventitia, rupture of these aneurisms very readily takes place. The part which primary fatty degeneration of the vessels plays in the causation of cerebral haemorrhage has been insisted upon by Paget. This condition of the vessels is found at all ages, and in cachectic children even THE NATURE OF THE LESION. 527 more frequently than among aged persons, so that care must be taken not to over-estimate its influence in the production of haemorrhage. Billroth has also shown that in a large nximber of cases this form of fatty degenera- tion of the small vessels is secondary to disease of the nervous tissues. Even after making these deductions from its importance as a predisposing cause, there can be no doubt that this condition does increase the hability to cerebral haemorrhage. (2) Vascular Tension. — It is very doubtful whether increase of the arterial tension ever gives rise to cerebral haemorrhage without disease of the vascular walls; but when the latter are degenerated then sudden increase of tension becomes a powerful predisposing cause of haemorrhage. Sudden exposure to cold may increase the arterial tension by inducing ex- tensive contraction of the cutaneous arteries. During the winter months it is very common for individuals to be found in an apoplectic condition on the streets, and taken up by the police supposed to be drunk. Such cases occur usually in persons beyond middle age, their breath may smell of alcohol, and they may even be known to have been drinking during the evening. The evening has been spent in a heated apartment, where, under the conjoined influence of a high temperature, alcohol, and emotional excitement of various kinds, the cutaneous vessels have become dilated, the skin bathed in perspiration, and the cardiac action increased. On going out into the cold air the surface becomes suddenly chilled, the cutaneous vessels contract, the arterial tension becomes immediately greatly in- creased, the internal organs become gorged with blood, and if, as is frequently the case, the walls of the cerebral vessels are weakened by disease, rupture takes place (Fothergill). The hypertrophy of the left ventricle which is associated with con- tracted kidney takes a more active part in the production of cerebral haemorrhage. Avoiding as much as possible controversial points, it is beyond question that contracted kidney is associated with a general con- dition in which the walls of the arterioles of the entire body become thickened, inelastic, and the lumina of the vessels themselves much dimi- nished in size. This condition greatly obstinicts the flow of blood from the heart towards the capillaries, and the left ventricle becomes the subject of compensatory hypertrophy, with the effect of producing a permanent increase in the arterial tension. And whatever may be the nature of the primary change in the arteries, whether a hypertrophy of the muscular coat, or sclerosis of the external coat, or both combined, the walls of the vessels undergo in long-standing cases degenerative changes which render them brittle and easily ruptured. Obstruction to the return of the venous blood from the brain probably also predisposes to haemorrhage, but its direct effect must be small. The obstruction may be temporary or permanent. Temporary in such actions as coughing, sneezing, laughing, or straining at stool, and per- manent in affections of the mitral and tricuspid valves, obliteration and compression of the cerebral sinuses, compression of the jugulars and 528 FOCAL DISEASES, ACCORDING TO superior vena cava, and affections of the lungs as emphysema and fibroid phthisis. (3) Condition of the Tissioes. — Rochoux advanced the theory that spon- taneous haemorrhage is generally preceded by a process of softening of the cerebral tissue, to which he gave to this process the name of ramollissement hemorrhagipare. In consequence of the change of consistence of the nervous tissue, the small vessels lose their natural support, and become unable to resist the pressure of the blood. It is now generally beheved that the softening is a secondary process, the result partly of the imbi- bition of blood serum, and j)artly of inflammation excited by the ex- travasation in the sui'rounding tissues. Haemorrhage may, however, occur as a result of softening of the tissues in cases of embohsm and thrombosis, but this condition will be noticed hereafter. Some authors think that haemorrhage is due occasionally to atrophy of the cerebral substance, and believe that the vessels then rupture in consequence of their becoming dilated in order to fill the vacuum. Bu.t the reduction in the size of the brain proceeds far too slowly for much dilatation of the vessels to result from it ; and the atrophy is compensated to some extent by thickening of the skull and increase in the size of the frontal sinuses, but chiefly by increase of the cerebro-spinal fluid. (4) State of the Blood. — Various diseases, the essential condition of which apjpears to be caused by some change in the composition of the blood, occasionally lead to cerebral haemorrhage. Cerebral haemorrhages have been observed in pyaemia, in the typhoid state, scorbutus, j)urpura, chlorosis, leucocythaemia, pernicious anaemia, and icterus, but are excep- tionally met with in these diseases. § 719. Other Predisposing Causes — Some families exhibit a predisposition to cerebral hsemorrhage, hence it has been assumed that the disease is hereditary. The action of heredity in predisposing to haemorrhage is, however, only an indirect result of the inherited tendency to arterial degeneration. It was formerly believed that some individuals inherited an apop- lectic constitution. This was supposed to be characterised by broad chest, short neck, large abdomen, powerful muscular system, and florid complexion. Exact statistics, however, prove that cerebral heemorrhage does not spare any constitution, and that poorly-nourished, thin persons are as frequently attacked as the plethoric. One of the most important predisposing causes of the disease is age. Cerebral hsemorrhage is rare before the fortieth year, relatively frequent afterwards. It must not be forgotten that the disease attacks young persons, and it has been observed in THE NATURE OF THE LESION, 529 infants and even at birth. Meningeal hsemorrhage is relatively common in early childhood. Sex undoubtedly exercises, a certain degree of influence in predisposing to cerebral haemorrhage, probably owing to the fact that men are more frequently exposed to the exciting causes of the disease. The proportionate frequency with which men and women are attacked has been variously estimated by different authors, but it may safely be asserted that the ratio of 2"1 rather under than overstates the proportion. The influence of occupation in predisposing to cerebral haemorrhage has not yet been satisfactorily determined, and the same may be said with regard to the influence of climate, since the immunity from the disease once attributed to warm climates has recently been called in question. In Europe the disease is most common in winter, then in autumn and spring, and least so in summer. Altitude appears to exert some influence in the production of the affection, since it is very common in the elevated regions of Mexico, of the Cordilleras, and the Andes. Certain substances, as alcohol, predispose to haemorrhage by inducing fatty degeneration of the vessels. § 720. Symptoms. — The symptoms vary greatly according to the situation and extent of the lesion ; but the mode of onset being sudden and the lesion of a destructive character, the initial group of symptoms bear a general similarity to each other in all cases. 1. PreWjOnitory Symptoms. — The attack is frequently ushered in without any premonitory symptoms, and in no instance can any symptom be relied upon as an invariable antecedent of hsemorrhage. Premonitory symptoms may, how- ever, manifest themselves days and even weeks before the actual onset of the attack, and these are no doubt frequently caused by rupture of minute vessels prior to the graver event which ushers in the apoplectic condition. The usual fore- runners of the apoplectic attack are dizziness, headache, ringing in the ears, muscas volitantes, numbness in the hand or foot, muscular twitchings of the face or of some portion of the upper or lower limbs, especially of the fingers or toes, mistakes in talking or writing, vomiting, mental irritability and drowsi- 11 530 FOCAL DISEASES, ACCORDING TO ness. These symptoms may appear separately or variously combined, and although all of them may occur without being followed by an apoplectic attack, yet in the old and middle aged, especially when the arteries are degenerated, they should be regarded as warnings. 2. Modes of Onset. — For facility of description the mode of onset of cerebral haemorrhage may be divided into three prin- cipal classes: (i.) The apoplectiform onset; (ii.) the epileptiform onset ; and (iii.) the simple mode of onset (Bastian). (i.) Apoplectiform Onset — This mode of onset is characterised by sudden loss of consciousness with resolution of the limbs, and what is popularly termed "apoplexy." In a small number of cases the onset may be instantaneous. In the midst of apparent health the patient may fall insensible to the ground. In such cases the lesion, which need not necessarily be large, is usually found in the pons or medulla. The attack usually begins more gradually. The patient suffers from dizziness, abnormal sen- sations or pain in the head, mental confusion, difficulty of speech, drowsiness, nausea and vomiting, or a sense of great exhaustion ; and after some of these symptoms have con- tinued for a few minutes or longer the stage of unconsciousness comes on. When the apoplectic attack is well marked the patient lies in a state of profound coma, and is insensible to all kinds of stimuli. The face is usually flushed and swollen, though occa- sionally it may be pale and clammy, the lips are livid, the head and neck feel warm and are bathed in perspiration, the carotids and other arteries throb violently, the eyelids are closed, the conjunctivae injected, the eyeballs fixed, the pupils sluggish to light, the respiration is usually deep, with or without ster- torous inspiration and protrusion of the cheeks during ex- piration, the pulse is generally full and slow, and there is either complete muscular resolution, so that the limbs when raised drop like inert bodies, or the resolution is more marked on one side of the body than on the other. In the severest cases there is not only complete absence of voluntary motion, but all the reflex movements are abolished, with the exception of the cardiac and respiratory movements, and those concerned in THE NATURE OF THE LESION. 531 deglutition, the latter being generally retained as regards the pharynx and oesophagus. When this condition has been brought about by a severe lesion of the brain, the patient may die after a few minutes, a few hours, or a few days. In the slighter forms, however, the apoplectic state may last only a short time, and then gradually give place to other related symptoms. When the coma is not very profound, powerful irritations cause reflex movements, and in the lesser degrees of the apoplectic state, the patient, when loudly spoken to, raises his eyelids for a moment or two, and may even reply in a monosyllable when loudly pressed with any question. In such cases a difference can be detected between the two halves of the body; the ex- tremities of one side offer a certain resistance to passive motion, while those of the other sink, when unsupported, like inert masses ; the corner of the mouth on one side is lower than on the other, and the opposite naso-labial fold is strongly marked. (ii.) The Epileptiform Onset. — The epileptiform is a mere variety of the apoplectiform mode of onset. The patient, either with or without prodromata, drops down insensible in a kind of epileptic fit, and after a time it is discovered that the patient is paralysed on one side of the body. Temporary hemiplegia may follow severe attacks of unilateral convulsions due to a molecular lesion of the cortex, but in the cases under present consideration, the hemorrhage destroys a certain por- tion of the brain, and the paralysis initiated is more or less persistent. Although prodromata may be absent altogether, yet the epileptic attack is very frequently preceded either by pains in the head or by muscular twitchings, or the initial attack may be characterised by unilateral convulsions, and in these cases the half of the body convulsed corresponds with that which is subsequently paralysed. But when convulsions occur after paralysis has become established, it usually happens that the non-paralysed side is the one which is affected with clonic spasms, and in these cases there is probably co-existing, but unequal, damage to both hemispheres of the brain. Some of the patients whose hemiplegic condition is ushered in by convulsions speedily die, whilst others remain liable to 532 FOCAL DISEASES, ACCORDING TO a recurrence of epileptiform attacks at variable intervals ; in many cases no subsequent attack occurs, even though the patient live for many years. Another remarkable peculiarity with respect to cases initiated by convulsions is, that the period of stupor or partial unconsciousness may be prolonged for three, four, five, or even six weeks, and yet the patient may recover. In these casesj however, the patient is not deeply comatose, but lies in a somewhat lethargic condition, with eyes closed or only half open, and takes no notice of anything that is going on around him. A patient, on the other hand, who continues deeply comatose for forty-eight hours very rarely recovers. (iii.) Simple Onset. — In the simple mode of onset the patient may suddenly fall owing to paralysis of an inferior extremity, but the fall is not accompanied by any loss of consciousness. The patient may experience no pain, but usually complains of a feeling of " numbness " in the paralysed side of the body. This mode of invasion is very frequent in the slighter forms of hemiplegia. Temperature. — The variations of the temperature of the body in cases of apoplexy have been studied with great care by Bourneville. The temperature is at first lowered in all cases, sometimes reaching 96'5° F., and in the fulminating form of the disease it remains low until death. If life continue for ten or twenty hours the initial sinking gives place to a marked eleva- tion of temperature. If the primary depression is followed by a steady and continuous rise of temperature it is a very un- favourable sign, and in these cases the pyrexia may reach 108° F. before death. In the more favourable cases the initial lowering is followed by a stationary period, during which the temperature varies between 99° F, and 100-5° F, and continues to oscillate rather irregularly for from two to four days. If the case be going to terminate in recovery, and supposing there be no inflammatory complications of other organs, the temperature gradually falls to the normal standard, and there remains. When, however, the case is to terminate fatally in the course of a day or two more, the stationary period is followed by a rapid and continuous rise of temperature, which is a not less unfavourable sign than when the same occurs after the period of initial lowering. . THE NATURE OF THE LESION. 533 Conjugated deviation of the eyes, with rotation of the head away from the paralysed side and towards the hemi- sphere which is the seat of disease, usually occurs as a tem- porary symptom in all cases of severe cerebral hasmorrhage (§ 90). The eyes are usually fixed, but occasionally exhibit slight nystagmus. When the disease is situated in the posterior half of the pons the rotation is directed towards the paralysed side (Provost, Grasset). The rotation may completely disappear when the patient falls asleep. 3. Permanent Sym^ptoms. — The permanent symptoms caused by cerebral haemorrhage consist of paral3^sis of voluntary motion, generally limited to one side of the body (hemiplegia) ; various tonic or clonic spasmodic affections, also generally limited to one side of the body (hemispasm) ; and unilateral sensory disturb- ances, including affections of the special senses (hemiantesthesia). As these affections are not, however, peculiar to heemorrhage, we reserve consideration of them for the present. § 721. Disturbances of the Mental Functions. — The majority of those who have been attacked with cerebral heemorrhage do not regain their full mental vigour. Memory usually fails, more especially for recent events. In the daily affairs of life the judgment of the patients may not appear to have suffered, but they are unequal to any unusual intellectual effort; and at times the intellect may progressively decline, reducing the patient to a state of childishness or pronounced dementia. At other times they become peevish, whimsical, irritable, or give way to outbursts of passion. The mental affections con- nected with disturbance of speech (aphasia) will be hereafter considered. Trophic and Vaso-motor Disturbances. — Immediately after an attack the paralysed limbs of a hemiplegic patient are frequently redder and warmer than the corresponding healthy limbs. The difference in temperature may vary from a fraction of a degree to as much as two degrees. These symptoms are no doubt due to paralysis of the sympathetic. About twenty- four hours after the beginning of an attack the paralysed limbs may become swelled owing to a certain amount of subcutaoeous oedema. The temperature of the paralysed limbs gradually 534 FOCAL DISEASES, ACCORDING TO decreases, and is eventually lower than that of the sound side. When no oedema exists the skin may be dry and scaly. Acute Bed-sore. — This is an acute process of sloughing, which occasionally occurs over the centre of the gluteal region on the paralysed side, after cerebral haemorrhage or softening. The affection has already been sufficiently described (§ 114). Congestions and Hcemorrhages. — Congestions and actual hfemorrhages into the substance of the lungs, extravasations in or beneath the pleura, endocardium, and the mucous membrane of the stomach, as well as into the substance of the supra-renal capsules and kidneys, frequently accompany cerebral haemorrhage. SchifF and Brown-Se'quard produced experimentally hyperaemia, or haemorrhage of the pleiu-a and lungs, by certain lesions of the pons, middle cerebellar peduncles, and the optic thalami and corpora striata. These hyperaemic conditions and haemorrhages, whether in the lower animals or in man, are sometimes confined to the paralysed side of the body. The diminution of the contractile power of the walls of the arterioles on the paralysed side often gives rise to a perceptible difference between the radial pulses of the two sides. Inflammcdion of the Joints. — Some of the joints of the paralysed side of the body may become the subjects of a subacute inflammation, which usually begins from the third to the sixth week after the hemiplegia, although sometimes the joints inflame at a still later period after the beginning of the attack, and occasionally the affection shows itself as early as the fifteenth day. There are the two varieties of this articular inflammation, the one acute and the other chronic. In the fii'st variety the joint becomes red, hot, swollen, and, after death, acute sj-novitis, fre- quently with considerable exudation, is discovered. This form almost exclusively attacks the larger joints. A chronic joint aflTection has been described by Hitzig which seems to be pecuHar to the shoulder. The joint is almost immovable, painful on pressure, and, owing to paralysis of the muscles, the humerus semi-dislocated. Changes in Nerve Trunks. — Cornil has shown that in a certain number of cases there is a sub-inflammatory hypertrophy of the nerves or of their sheaths, and in such cases there is pain on pressure of the paralysed limb, especially marked along tlie course of the principal nerve-trunks. At other times the whole paralysed side may be generally tender, without any special limitation of the tenderness to the joints and large nerves. Muscular Atrophy. — In some rare cases an early and rapid wasting takes place in the muscles of one or both hmbs a few weeks after the onset of the paralysis, but in these cases there is reason to beheve that the fibres of the pyramidal tract have undergone secondary degeneration, and that the motor cells of tbe anterior horns of the cord have become implicated in the process. Arrest or Retardation of Growth in Paralysed Limbs. — When hemi- plegia occurs in childhood, the a.rm and leg, or the arm only, on the para- THE NATURE OF THE LESION. 535 lysed side grow more slowly than on the sound side, so that as growth advances the limbs of the paralysed remain permanently smaller than those of the opposite side. The arm is more frequently affected than the leg, and there is always a certain amount of muscular rigidity of the affected extremity. Skin, Hair, and Nails. — The skin of the paralysed side sometimes undergoes trophic changes, which involve the cutis and subcutaneous tissue, so that a fold pinched up by the fingers feels thicker than normal. The hair grows better on the afifected side, and the nails become yellowish, marked with ridges, brittle, and curved. § 722. Morbid Anatomy. — Morbid anatomists usually divide cerebral haemorrhage into two varieties, named respectively pwnctiform and massive hsemorrhages, Punctiform, hmmorrhages occur in the form of a number of minute points of the size of a pin's head, or even smaller. They result from rupture of capillary vessels, and are invariably multiple. Capillary haemorrhages are observed in the tissues surrounding massive haemorrhages, or in parts which are the seat of softening, and they are met with in considerable numbers in the cortex of the brain in consequence of thrombosis of the venous sinuses. At other times extravasations of blood are found in the lymph sheaths of the vessels, and they must then be regarded as minor degrees of the massive haemorrhages. Massive hcemorrhages may be of various sizes, being sometimes as small as a pea, at other times large enough to destroy almost an entire hemisphere. The hemorrhage may either separate the nerve fibres of the white substance or rupture them, the latter event being by far the more frequent. When the nerve fibres are pushed aside by the haemorrhage without rupture the form assumed by the clot will be deter- mined by the direction of the fibres, but when the fibres are ruptured the clot is round or oval. In the cortex the form assumed by the haemorrhage is largely determined by the dis- position of the convolutions and membranes, so the effusion usually spreads out laterally and assumes an irregular form. Massive haemorrhages are, as a rule, single, although several foci may occasionally be observed, and it is not unusual to find traces of many extravasations of various ages in the same brain. Haemorrhagic foci may occupy any part of the brain, but 536 FOCAL DISEASES, ACCOEDING TO they are much more frequent in certain parts. The favourite seats are the caudate and lenticular nuclei, and the optic thai ami. Recent Focus. — In the recent condition the apoplectic focus forms a dark red clot, which is soft and uniform in character throughout. It is frequently mixed with the debris of the substance of the brain. The internal surface of the cavity is irregular and consists of torn shreds of cerebral tissue. This is surrounded by a zone of variable thickness, averaging a few lines in depth and gradually merging into the healthy tissues, composed of softened tissue saturated with blood serum, and frequently the seat of punctiform haemorrhages. If the nerve fibres have been simply separated from one another without rupture, then the detritus of cerebral tissue in the internal surface of the walls of the cavity is absent, and the softening and punctiform hsemorrhages of the surrounding tissues are much less marked. If the clot be floated out under water, it is sometimes possible to detect the miliary aneurism from which the primary extravasation took place. Period of Ahsorj)tion and Repair. — If the hsemorrhage does not end fatally after a few hours structural changes take place, both in the clot and surrounding tissues, which lead to the absorption of the former and to a certain amount of repair in the latter. The blood-clot after coagulation parts with its serum, and the injured tissues surrounding the clot become softened, partly by imbibition of serum, but chiefly owing to a retrograde fatty metamorphosis of the torn fragments of brain tissue. The softened tissues become mixed with the clot so as to form a dark, chocolate-coloured mass, of the consistence of gruel, the more fluid constituents of which are soon absorbed. The hsematine is dissolved, and soaks into the tissue round the clot to a considerable distance, until it is absorbed. As a result of this process the pulpy material filling the cavity passes from its first dark red to a brighter red, and finally to a saffron colour. A reparative process now begins, by means of which the hs3morrhagic focus is converted into a cyst. The first step in the reparative process is the formation of a fibrinous capsule round the entire periphery of the clot. It is at first a line or more in thickness, soft as jelly, and of a trans- THE NATURE OF THE LESION. 537 lucent yellowish tint. At a later period this capsule becomes converted into a much thinner but stronger layer of fibrillar connective tissue, which permanently shuts off the apoplectic deposit from the surroundiog substance of the brain. The fluid contained in the cyst is at first turbid, but after a time becomes transparent and limpid. These cysts, however, contain not fluid merely but also a loose spongy connective tissue, which is suspended iu the fluid like a film. But the reparative pro- cess does not always end here; the whole of the fluid may become gradually absorbed, and the opposite walls of the cavity may ultimately come into contact, and adhere to one another by a connective tissue, which usually contains a consider- able amount of pigment. This constitutes the hsemorrhagic or apoplectic cicatrix, which consists merely of a thin strip of con- nective tissue. Superficial foci in the cortex pass through similar phases, and after cicatrisation they appear as yellow indurated spots which have been taken for vestiges of encephalitis. Duration of the Reparative Process. — The clot is soft and homogeneous during the first three or four days. At this time the process of softening and separation of the internal surface of the cavity, and the absorption of the fluid contents, reach their maximum activity at the eleventh or twelfth day. The reparative process which leads to the formation of the capsule begins usually from the seventh to the ninth, the cyst is com- plete about the twentieth, and the lining membrane is organised from the thirtieth to the fortieth day. Circumstances which prevent the Reparative Process. — Various circumstances delay or entirely prevent the reparative process. The principal of these are, a too extensive sero-san- guineous infiltration of the surrounding tissues followed by a co-extensive area of softening, an excess of the irritative pro- cess necessary to repair, which gives rise to secondary encepha- litis, a fresh hasmorrhage and dropsy of the cyst, leading to distention and consequent pressure on the surrounding tissues. Repair of injury to the brain from haemorrhage may be pre- vented, like repair of injuries of every part of the body, by the general state of the health in various conditions of debility. § 723. Prognosis. — The prognosis in any given case depends 538 FOCAL DISEASES, ACCORDING TO upon the opinion formed of the extent and situation of the lesion taken in conjunction with the age and previous state of health of the patient. Death not unfrequently takes place during the apoplectic condition. If the patient cannot be roused at all, if there be no signs of reflex activity when the conjunctiva is touched, while there is involuntary passage of fseces and urine, and well-marked stertor, the patient may die rapidly within a few hours, or even a few minutes ; and the persistence of a slighter degree of these symptoms without abatement is a sign of great gravity. Laboured respiration and quickness with marked irregularity of the pulse, are also un- favourable signs. A marked and persistent depression of the tem- perature is regarded by Charcot as an almost certainly fatal sign. If the patient has recovered from the apoplectic condition, then the prognosis will greatly depend upon the age and general condition. Granular disease of the kidneys, a general state of malnutrition, or evidences of senile degeneration of the arterial system, will render the ultimate prognosis grave in cases where the extent and situation of the hsemorrhage itself would cause no danger to life. A sudden rise of tempera- ture in cases of cerebral haemorrhage is a very grave indication, unless some inflammatory complication be present to account for it. A sudden depression of temperature, with increase or renewal of a pre-existing comatose condition, indicating as it does the occurrence of a fresh haemorrhage, is also of serious import. Acute sloughing of the buttock on the paralysed side, cotn- mencing within a few days after the onset of the apoplectic attack is, according to M. Charcot, of fatal significance. Decided difiiculty of deglutition and articulation is also a serious symptom, being indicative of marked interference with the functional activity of the medulla and pons. When the patient has outlived the apoplectic attack, the period of reactive inflam- mation brings new dangers, when death may result. When the inflammatory period is passed there is compara- tively little reason to expect a fatal result from the brain lesion itself or from its more immediate complications. In middle- aged and old people, however, there is a constant danger of a recurrence of the haemorrhage. The dangers of the apoplectic THE NATURE OF THE LESION. 589 attack having been surmounted, the point which has to be determined is the degree of improvement likely to take place in the patient's mental faculties, in his power of articulation and speaking, and as regards the probability of restoration of motor power to his paralysed limbs. In the majority of instances when the first loss of conscious- ness has passed away, the patient is left free from any very decided mental defect, except a certain amount of mental weak- ness and a tendency to emotional displays. In rare cases the hemiplegic attack is followed by a chronic maniacal condition, which may pass into a state of complete dementia. This condition is apt to follow limited cortical haemorrhage of the occipital lobes, especially in elderly people, but the hgemorrhage may itself be only an effect of previously-existing degenerative changes. Large lesions occurring in infancy or at the time of birth, either in the substance or on the surface of the brain, often induce a semi -idiotic condition. § 724, Treatment. — The aims of treatment are (1) to avert a threatened attack; (2) to treat the apoplectic condition; (3) to allay excitement during the stage of inflammatory reaction ; and (4) to restore power to the paralysed limbs, and to improve the other morbid conditions which accompany the hemiplegic state, (1) Prophylaxis. — In devising measures to prevent a threa- tened attack, each case must be made the subject of special study; and much depends for the success of these on the age, general state of health, and hereditary tendencies of the patient. Bodily and mental rest are absolutely necessary. The patient ought to be kept cool, with his head and shoulders well raised. If the patient be beyond middle age, with signs of arterial degeneration and a weak intermittent action of the heart, stimulants, cardiac tonics, and the frequent administration of easily-assimilated fluid nutriment is necessary. In the presence of a moderate amount of granular disease of the kidneys with cardiac hypertrophy and high arterial tension, saline purgatives are indicated. (2) Within the last few years our treatment of the apoplectic condition has undergone a great change. Bleeding was regarded 540 FOCAL DISEASES, ACCORDING TO as the great remedy for the apoplectic condition from the time of Hippocrates down to within a few years ago, when the teachings of Todd and Trousseau produced a reaction in the opposite direction. When, however, haemorrhage takes place in a case associated with high arterial tension, a small bleeding may, by lowering the blood pressure and thus diminishing the intracranial pressure, avert for a time threatening symptoms. If the heart be feeble, with compressible pulse, then bleeding is entirely inadmissible. If there be much heat of the head, with violent throbbing of vessels, pounded ice in a bladder or india-rubber bag, or evaporating lotions should be applied while the head and shoulders are raised, and everything about the neck loosened. In the present day it is superfluous to condemn the barbarous practice of applying mustard plasters to the calves of the legs. A stimulating treatment is required when the heart's action is feeble and the respiratory centre is threatened. In such a case the patient's face is cold and clammy, the pulse feeble, and the respiration hesitating and intermittent, or it may be assuming the Cheyne-Stokes character. If the disease be characterised by recurring epileptiform attacks, bromide of potassium may be administered, and if there be a restless condition, with more or less of delirious wandering, the same drug or bromide of camphor may be useful. If the bowels be constipated, an enema containing castor oil or castor oil and turpentine may be administered, or two drops of croton oil may be given. The state of the bladder must also be attended to, and a catheter used if necessary. In many cases no drugs are required during the apoplectic stage, and purgatives should not be resorted to on all occasions as a routine treatment irrespective of the nature of the case. (3) If the patient survive the first shock of the apoplectic attack the less we interfere during the first few days the better. He must be kept as quiet as possible both in body and mind, and his diet and secretions must be carefully regulated. When the reactive febrile symptoms appear cold should be applied to the head, but the old practice of bleeding at this stage is to be strongly condemned. If headache be pre- sent along with persistent wakefulness or delirium, it may be THE NATURE OF THE LESION. 541 necessary to administer a full dose of bromide of potassium or even an opiate or chloral. During this time great care must be taken to prevent bed-sores on the paralysed side, by paying constant attention to the state of the bedding and securing ex- treme cleanliness. In severe cases the patient should be placed on a water bed from the first where this is possible. (4) The most efficient means of promoting the improvement of the condition of the paralysed nerves and muscles is a thorough attention to the general health of the patient. The treatment which it will be necessary to adopt will depend on the age, habits, and constitution of the patient, and on the pre- sence or absence of any special concomitant disease. The general principles of treatment, however, are to take care that the patient has easily-digestible and nutritious food ; that all circumstances which might cause mental excitement are avoided; and that the patient has a due amount of repose and sleep. In the hemiplegias of elderly people, which are usually associated with miliary aneurisms, great care must be taken that the cir- culation is not subjected to any sudden strain, and with this object it is necessary to take care that the bowels do not become constipated, lest the straining at stool should induce another attack. Iodide of potassium is often beneficial. The patient should also take open-air exercise in a chair or carriage when- ever the weather is suitable; and much good may be done at a later period of the disease by sponging with salt water, either tepid or cold, or even by shower baths. When there is advanced degeneration of the arteries or high arterial tension, great caution is necessary in the use of cold sponging and shower baths, since the sudden impression on the cutaneous surface will be followed by contraction of the arterioles dis- tributed to the surface of the body, and this will be followed by sudden increase of the arterial tension, and consequent risk of the rupture of another vessel. It may indeed be laid down as a rule that hemiplegic patients should only use baths of moderate temperature. These general measures should after a time be followed by local treatment of the paralysed limbs. The first local measures to be resorted to are passive movements of the paralysed limbs, and friction of the skin by means of a 542 FOCAL DISEASES, ACCORDING TO flesh brush, flannel, or the palm of the hand. When a paralysed limb is painful, gentle rubbing is very soothing and grateful to the patient. The patient may be directed to make voluntary efforts to move the limbs. Electricity is one of the most valuable agents we possess in the treatment of paralysed limbs. Both the faradic and galvanic currents have been employed, but the latter appears to be the more generally useful. The constant current has been employed in three different ways. According to one method the current is passed through the brain, in a second it is passed through the cervical sympathetic, while in a third it is directly applied to the paralysed limbs. The practical rules which must be observed in carrying out the treatment are the following : — (a) This metliod of treatment should not be adopted in the early stage of hemiplegia, as injury may be done by over-stimulation of the brain. (6) The duration of each application through the brain ought to be short, not exceeding three minutes. (c) The current should be weak, more especially in the case of elderly people — such, for instance, as that derived from five to ten or at most fifteen Leclanch^'s cells. (d) The electrodes are to be placed on the mastoid processes, or one on the mastoid process and the other on the back of the neck. (e) The electrodes should be placed in position when the index is at zero, and the current is then gradually increased and, after two or three minutes' application, gradually diminished before the electrodes are re- moved. Sudden interruptions and raj)id reversals of the current ought to be avoided. In the second method the current is passed through the cervical sympathetic. In this method the electrodes are placed over the coiu-se of the sympathetic in the neck, and it aj^pears to be indifferent whether the anode is above and the cathode below or the reverse. The currents em- ployed may be stronger than when the brain was directly acted upon. From fifteen to twenty-five Leclanche's cells may be used. In the third method the electrodes are used along the course of the nerves, the negative pole being placed near the plexus to which the affected nerve belongs, or over the corresponding part of the vertebral column, and the positive pole over the trunks of the nerves. Some, however, recom- mend descending instead of ascending currents, but it does not appear to be of much consequence which is used. The cmTent from thirty Leclanche's cells may be used for about eight minutes, and in order to increase its stimulating action the intensity may be alternately increased and dimi- nished, while the circuit is kept closed. Interruptions and reversal of the THE NATURE OF THE LESION. 543 current should only be used for the purposes of diagnosis. This mode of applying galvanism to the paralysed limbs does good in cases of clonic spasm after hemiplegia, and in some cases of " late rigidity ;" but when the contracture has become permanent, so that it does not intermit during sleep, it is hopeless to expect any benefit from treatment. Faradic currents have been employed in contractures for the purpose of acting, not on the contracted muscles, but upon their antagonists, but it does not appear that much benefit has ever resulted from this treatment. The disturbances of sensibility on the paralysed side do not usually require any special treat- ment, since the measures which are directed to mitigate the motor paralysis exercise a favourable influence on any existing sensory impairment. If there be hemiansesthesia, metallo-thera- peutics, as employed by Charcot, which will be described in the section on hysterical hemiansesthesia, may be adopted, but our knowledge of this subject is too recent and too imperfect to enable us to form a definite opinion of its merits. (b) Meningeal Rcemorrhage. Definition. — By meningeal hsemorrhage is here meant an extravasation of blood- between the membranes or on the surface of the brain. § 725. Etiology. — The most frequent causes of meningeal apoplexy are injuries of the skull, by means of which the main meningeal arteries, the sinuses, or the vessels of the pia mater are ruptured, but this subject belongs to surgery. Aneurisms of the arteries at the base of the skull may by rupture give rise to meningeal haemorrhage. In a case which came under my observation, a large meningeal hemorrhage was caused by rupture of an aneurism, about the size of a pea on the left Sylvian artery, about an inch from its origin. Another aneurism unruptured, symmetrical with it in size and position, was found on the right Sylvian artery. Next to the middle cerebral, the basilar artery is most frequently affected with aneurism. Hseraorrhage may also take place from the veins, and large meningeal haemorrhage may result from thrombosis of the sinuses, especially the superior longitudinal sinus. Blood may make its way from the substance of the brain into the meninges through rupture of the cortex. Meningeal 544 FOCAL DISEASES, ACCORDING TO hsemorrhage may result in the course of infectious diseases, and chronic dyscrasise, and frequently occurs in the course of the chronic degeneration of the cortex of the brain, which underlies progressive paralysis of the insane. The Qneningeal apoplexy of new-born children is caused by certain accidents attending childbirth. § 726. Symptoms. — It will suffice if we point out here the differences which exist between the symptoms of cerebral and meningeal hsemorrhages. The clinical history of meningeal haemorrhages of traumatic origin is usually complicated with other cerebral symptoms directly resulting from the injury, such as concussion, and the same may be said with regard to the cases Avhere an intracerebral hgemorrhage has made its way to the surface of the brain, as well as with regard to the hgemorrhage which accompanies general paralysis. Hsemorrhage caused by rupture of an aneurism forms the least complicated class of cases. In severe cases the patient becomes suddenly apoplectic without any warning, or with only slight premonitory symptoms, such as headache, dizziness, and vomiting. The paralysis is commonly general, affecting all four extremities uniformly, and only in rare cases is hemiplegia met with. Epileptiform convul- sions are also frequent in meningeal hsemorrhage, and vomiting is another sign often observed. These cases are accompanied by profound coma, and death results in a few hours, or at most a few days. In less severe cases the patient may partially recover after a few hours from the apoplectic state, and then may complain of headache, be delirious or somnolent, until he becomes finally comatose. In other cases the patients do not become immediately apop- lectic, but complain of headache, dizziness, weakness or numb- ness of the extremities, on one or on both sides; there is also more or less stupor, but the fatal coma may not supervene for a long time. In these cases the haemorrhage appears to be small at first and gradually to increase. If an aneurism of considerable size have existed for some time before the occurrence of hsemorrhage, the apoplectic THE NATURE OF THE LESION. 545 attack may be preceded by some of the symptoms which in- dicate the existence of a cerebral tumour. The more usual of these symptoms are headache, double optic neuritis, paralysis of the facial nerve in aneurism of the internal carotid, of the third nerve in aneurism of the posterior communicating artery, and vomiting, epileptiform convulsions, and disorders of deglutitioD, speech, and respiration in aneurism of the basilar artery. In the meningeal haemorrhages of the new-born, the children are either born dead or in a condition of asphyxia, and die soon afterwards. If respiration be established the infant remains weak, somnolent, or comatose, and dies after a few days from convulsions. Sometimes the children are weak and somnolent at birth, and remain in this condition from one to three weeks, when vomiting, dyspnoea, convulsions, and coma supervene and soon prove fatal. § 727. Morbid Anatomy. — The blood may make its way into the arachnoid space in consequence of injury to the dura mater, or from the vessels of the pia mater, or from the cerebral vessels and subsequent rupture of the pia mater. When the extravasation is large the haemorrhage spreads extensively through the arachnoid space, so that an entire hemisphere, or exceptionally the surfaces of both hemispheres, may be covered with a thick layer of blood. When a large collection of blood has formed at the base and around the pons varolii, it may make its way into the ventricles through the great trans- verse fissure, and pass down through the aqueduct of Sylvius to the fourth ventricle. The quantity of the effused blood may vary from a few drops to half a litre or more. The pigmented spots sometimes found on the meninges and surface of the brain seems to indicate that small meningeal haemorrhages may be absorbed, but large haemorrhages invariably prove fatal. The appearances presented by the brain vary greatly, accord- ing to the amount and seat of the haemorrhage and the time at which death takes place. Haemorrhage from the dura mater, if large, compresses without rupturing the brain. In such a case the gyri are found flattened and the substance of the brain pale. Haemorrhage from rupture of the vessels of the pia mater or of the brain itself, and especially rupture of an aneurism JJ 54!6 FOCAL DISExVSES. of the larger sized arteries at the base of the brain, may cause considerable destruction of cerebral tissue. § 728. The prognosis is more unfavourable in meningeal than intra-cerebral haemorrhage, inasmuch as it is apt to be more copious, but the treatment of the two affections is similar. Trephining may possibly be of use in some cases of meningeal haemorrhage. 547 TEl CHAPTER V (I.) GENERAL CONSIDERATION OF FOCAL DISEASES, ACCORDING TO THE NATURE OF THE LESION (Continued). 3. INTRACRANIAL TUMOURS. § 729. Definition. — Intracranial tumours consist of circum- scribed pathological growths situated within the cavity of the skull. § 730, Etiology. — Tumours of the brain arise from similar causes to those which give origin to tumours in other localities. For the sake of convenience, cerebral tumours may be divided into {a) New formations ; (6) Vascular tumours ; (c) Parasites. Hereditary predisposition plays an important part in the pro- duction of new formations. Cancerous and tubercular tumours and syphilitic gummata depend upon a general constitutional taint, and it is also probable that glioma, sarcoma, and other tumours are more liable to arise in some families than in others. Cancer is one of the most common tumours of the brain, and is generally primary. When secondary it often follows cancer of the orbit. It is a disease of adult and advanced age, the largest number of cases being found between the ages of thirty and sixty years. Tubercle on the other hand is rarely primary, but is generally associated with tubercle of the lungs or cheesy glands ; it is essentially a disease of youth, being most common between the ages of three and thirty years. It is probably the most frequent of all cerebral tumours. Syphilitic gummata may be met with at every period of life. Cerebral tumours are more frequent in men than in women. Out of 329 cases of cerebral tumours of all cases collected by 548 FOCAL DISEASES, ACCORDING TO Ladame 208 were male, 95 female, and in 26 the sex was not stated, so that, according to this computation, the proportion is rather more than two to one. Injuries of the skull act as exciting causes in the production of cerebral tumours. Several cases have come under my own observation in which the disease dated from a blow on the head, and the tumour in these cases frequently grew at a place corresponding to the seat of injury. Vascular tumours consist of aneurisms of the cerebral arteries and erectile tumours. Aneurisms are observed at all ages, but they are more common between the ages of forty and sixty years, when the vessels begin to undergo atheromatous degeneration ; the causes of erectile tumours are unknown. The parasites met with in the brain are the cysticercus and echinococcus. § 731. Symptoms.— Headache is one of the earliest and most striking of the initial symptoms of intracranial tumours. Ladame found this symptom in two-thirds of the cases collected by him. Headache is more violent in intracranial tumour than in any other disease except meningitis and the uraemia of chronic Bright's disease ; it consists of an acute lancinating or severe boring pain, which may continue many weeks without intermission, and is aggravated by impressions of light, noises, and all movements of the head. The pain sometimes occupies the occipital and at other times the frontal or temporal regions; but its seat has no necessary relation to the situation of the tumour, although constant occipital pain is often associated with cerebellar tumour. Neuralgic headache from irritation of the fifth may be associated with the more profound headache of general pressure. Tenderness on percussing the skull may sometimes be observed at a point corresponding to the situation of the tumour (Ferrier). Dizziness is a frequent initial symptom, and it may be present with or without cephalalgia. Paroxysms of head- ache and dizziness may be the only symptoms present for months, and the patient may feel well in other respects. Dizziness is probably caused by alterations in the circulation of the brain induced by the growth of the tumour; but the insecurity on assuming the erect posture, which is one of the \ THE NATURE OF THE LESION. 549 main elements of vertigo, is frequently caused by pressure on the labyrinthine fibres of the auditory nerve. Sensory disturbances are generally ushered in by hyper - sesthesia or some other irritative phenomena, which are after a time followed by anaesthesia. Wandering pains, formication, tingling, and numbness alternate with one another before there is a distinct diminution of sensation, and these symptoms do not entirely cease until complete anaesthesia is established. Ladame found cutaneous ansesthesia in one-seventh of his cases. Neuralgia of the trifacial nerve arises from a variety of causes, but when all the three divisions of the nerve are simul- taneously affected the presence of intracranial tumour is to be suspected. The pain occurs in paroxysms, and is usually asso- ciated with numbness, formication, itching, and the feeling of the part being swollen. When sensation is diminished on the painful side the pressure of a tumour on the nerve may be suspected, and the diagnosis is rendered more certain if dis- turbances of other cranial nerves are present. Motor disturbances are generally ushered in by phenomena of irritation, to be followed by paralysis. The irritative symptoms are cramps of various parts or tremor of one of the extremities or of half the body. The cramps may vary from slight spasmodic twitches of the muscles of the face or of other special groups of muscles, to persistent tonic, clonic, or choreiform muscular spasms in the extremities ; or there may be epilepti- form convulsions, accompanied by unconsciousness. After a longer or shorter duration the irritative motor symptoms give place to paralysis, which creeps on gradually, and does not become complete for a comparatively long period. Hemiplegia is the more frequent form of paralysis, being present in a third of Ladame's cases. Permanent contractions of the paralysed extremities occur when the pyramidal tract is pressed upon or otherwise injured, but the spastic condition of the limbs is seldom so pronounced in intracranial tumours as in other focal diseases of the brain. The paralysed muscles atrophy apparently simply from disuse, and retain for a long time their electric excitability. Affections of the Special Senses. — With respect to the affec- 550 FOCAL DISEASES, ACCORDING TO tions of the special senses, those of sight are by far the most important Calmeil found amblyopia in two-fifths of his cases, and Ladame found amaurosis in one-fifth. The optic disc may present the appearance known as " choked disc " (Stauungs- papilla), or there may be neuritis (§ 207). The former is by far the most important sign of cerebral tumour, as it is generally present whenever there is increased intracranial pressure ; and although this condition is said occasionally to accompany fluid effusion, yet the usual cause is a solid growth. It is of the utmost importance for regional diagnosis to examine carefully for contractions of the field of vision, and for the different varieties of hemiopia. Diplopia is also a frequent symptom of tumours at the base of the brain, caused by an affection at the origin or pressure in the course of the third, fourth, or sixth cranial nerves. The pupils vary; they may occasionally be contracted or unequal, but when by the growth of the tumour the intracranial pressure becomes great, they are always dilated and react feebly to light. The sense of hearing is also frequently affected. Calm6il found some disturbances of hearing in one-ninth of his cases ; Ladame says that the sense of hearing is affected only one half as often as the sense of vision. The auditory disturbances usually consist of dulness of hearing and rushing noises, but complete deafness is sometimes observed. The injection experiments of E. Weber have shown that there is a communication between the arachnoid cavity and the labyrinth by means of the aqueduct of the cochlea, and con- sequently increased intracranial pressure may produce an affection of the auditory apparatus similar to that which occurs in the eyes under the same circumstances. Alterations of hearing may likewise be caused by pressure on the trunk of the auditory nerve or on its nuclei of origin in the medulla and pons. Pressure on the labyrinthine fibres of the auditory nerve may occasion vertigo and disorders of motor co-ordination similar to those observed in Meniere's disease. The sense of smell is relatively seldom affected in cases of tumour of the brain. The number mentioned in literature, how- THE NATUKE OF THE LESION. 551 ever, is not a true criterion of the real number affected, since the patient is very apt not to mention the loss of smell unless it be entirely lost, and the physician is apt not to make any special investigation of it. Ladame found the sense of smell distinctly diminished or entirely lost in ten only of his collected cases, and never present as the only symptom. The sense of taste is likewise only rarely affected. In Ladame's collected cases mention is made of alterations of this function only seven times, once the affection was unilateral, and the sense was only rarely completely lost. There are good grounds, however, for believing that if taste were carefully tested in all cases of cerebral tumours, alterations would be more frequently found. The organic functions always become more or less injured in intracranial tumour. The intense cephalalgia alone prevents the patient from sleeping, and the continual wakefulness reacts on the general health. Vomiting is frequently associated with paroxysms of head- ache and vertigo, but it may occur independently of these. It is often extremely obstinate and may continue for hours, and when it recurs frequently the general nutrition suffers greatly. Constipation is usually present, but in some cases it may alter- nate with diarrhoea. Irregularity of the heart's action and slowness of the pulse have been frequently observed, probably from irritation of the vagus. Towards the end, however, the pulse becomes very frequent. The respiratory function is not often disturbed, but the rhythm may be quickened by irritation, and rendered slower by pressure, of the brain. Vierordt and Hegelmaier, by recording the movements of the superior abdominal region of rabbits on the drum of the kymograph, found that a moderate artificial pressure on the brain diminished the respirations by one-half, while they were increased in number by a stronger pressure. With moderate pressure the inspirations were fewer and the expirations longer. Polyphagia is an occasional symptom of cerebral tumour, but it does not prevent the progressive emaciation. Rosenthal mentions a case where the polyphagia was accompanied with diabetes mellitus. 552 FOCAL DISEASES, ACCOEDING TO Polyuria and saccharine urine, either separately or com- bined, are frequently met with. In these cases it is almost certain that there must be irritation of the floor of the fourth ventricle, but the irritation need not be direct. Rosenthal relates the history of a case where diabetes was caused by tumour of the pituitary body, and I have seen a case where polyuria was occasioned by a tumour situated at the base of the skull over the right cavernous sinus. Fever is not a usual symptom, but it is sometimes present during an attack of cerebritis, these complications being most frequently observed in the incipient stage of tubercular tumour. The nutritive disturbances do not maintain a due pro- portion to the gravity of the cerebral phenomena, nor does the nature of the tumour appear to exert a marked influence on the general health. Cases have been observed in which cancer of the brain had existed for some months without pro- ducing a perceptible influence on the nutrition of the body, and those suffering from sarcoma may even manifest a tendency to obesity. As a rule, however, the subjects of tubercle and cancer sooner or later exhibit traces of cachexia. Tumour of the brain may act injuriously on nutrition in several ways. A state of great marasmus is sometimes induced by frequently recurring vomiting, while at other times the vital powers of the patient become exhausted by incessant headache and sleep- lessness. Psychical disturbances are frequently observed in cerebral tumour, but the statements of authors differ considerably with respect to the relative frequency of the symptom. Andral and Durand-Fardel assert that mental disturbances occur very seldom, while Calmeil observed psychical disorders in one-half, Friedreich in 43 per cent, Lebert in one-third, and Ladame in rather more than a third of their cases. Symptoms of mental irritation fre- quently precede those of depression. The irritative symptoms consist of mental excitement and those emotional disturbances which are usually known as hysterical, ideas of grandeur, with consequent extravagance, hallucinations, delusions, and out- bursts of passion which may amount to maniacal fury. The symptoms of depression consist of drowsiness, apathy, loss of speech, and imbecility. The affections of speech which occur THE NATURE OF THE LESION. 553 in cerebral tumour are variable in character. Ladame found affections of speech in 45 of his collected cases. Terminal Phenomena. — As the tumour grows in size the brain becomes compressed to such an extent that its functions become gradually abolished, and the terminal phenomena of the affection are ushered in. These consist of extreme emacia- tion, widely spread anaesthesia, blindness and diminution or loss of one or more of the other special senses, motor paralysis often implicating all the extremities, imbecility and deep and enduring coma. § 732, Morbid Anatomy. — The morbid growths which con- stitute intracranial tumours are very variable, and, regarded from the standpoint of pathological anatomy, have little or no affinity with each other, but are conveniently grouped together for practical purposes on account of their clinical affinities. The brain is surrounded by unyielding osseous walls, and the development of any foreign body within the cranium encroaches upon the space occupied by it, and consequently there is a close similarity in the symptoms caused by intracranial tumours however different in nature. (a) Varieties of hhtracranial New Formations. (1) Glioma. — The gliomata form tumours which vary in size from a cherry-stone to that of the closed fist ; they are vascular, of a white or greyish-red colour, and are never distinctly circumscribed from the tissues of the brain, the grey matter of which they much resemble in consistence and colour. The hemispheres of the brain are the favourite seats of gliomata, although they may appear in any part of the brain or spinal cord. Gliomata are composed of a matrix, which varies in consistence, and an abundant admixture of cells and nuclei. The cells vary in shape and size ; they are sometimes round or oval, with granular contents and one or two nuclei ; at other times spindle-shaped or stellate, and provided with fine processes, which are continuous with those of adjoining cells. There are two principal varieties of gliomata, the hard and the soft. In the hard gliomata the cells are scanty, and usually contain several nuclei. The matrix is formed of fine fibrillae, which are more or less parallel to one another, and can sometimes be isolated into long threads. In the hardest forms the matrix is no longer formed of long, separable fibrillae, but of a finely reticular substance, which can only be separated into short stiff fibres. At times part only of the tumour is hard, and it then contains one or more hard kernels, which may equal in density fibro-cartilaginous 554 . FOCAL DISEASES, ACCORDING TO tumours. True cartilaginous structure has, however, never been found in these tumours. The hard ghomata are allied in general characters to the fibromata, and intermediate forms are met with which are termed fihro-cjlio''mata. In ih.e fibro-gliomata the matrix consists of fibres forming thick bundles, or exhibiting a stratiform arrangement enclosing here and there nucleated cells. The soft gliomata contain more cells than the hard ; the cells vary con- siderably in size and form, but are generally small and deficient in plasma. The matrix consists of a fibrillary network, in the interstices of which the cells are imbedded. Transitional forms between the soft gliomata and other tumours are met with. When the number and size of the cells are increased, the tumours are allied to the sarcomata, and are therefore called glio-sarcomata ; and when the matrix assumes a mucoid character, the tumoiu- resembles the myxomata. The gliomata are sometimes richly supplied with rela- tively large blood-vessels, constituting what Virchow has named telean- gieotatic glioma. This form is characterised by the tendency to hsemorrhage, which always occurs in the centre of the tumour, and the appearances presented may closely resemble simple apoplexy. Haemorrhagic glioma usually occurs in the white substance of the hemisphere, where simple apoplexy is rarely seen; and in the former, even when the tumour is largely destroyed by haemorrhage, a narrow zone surrounds the clot, which is sufficient to reveal the origin of the mischief. Gliomata grow slowly, and the tumour generally attains a large size. That these tumours undergo retrogressive changes is shown by the fre- quent occurrence of fatty degeneration in their interior, but the changes instead of leading to a curative process are much more likely to cause haemorrhage as soon as the absorption of the fatty debris lowers and removes the pressure on the vessels in the interior of the tumour. By fatty metamorphosis and softening of the intercellular substance cavities form which may be distinguished from cysts by their irregular and uneven walls. In the vicinity of tumours where the tissues are reddish and softened, fatty grantiles, cholesterine crystals, neurogha nuclei, and frag- ments of axis cylinders may be found. (2) Hyperplasia of the pineal gland is, both in external characters and in the nature of its elements, very similar to gUoma. Virchow says that it forms a solid, greyish-red, slightly lobulated, or a smooth round tumour, which may grow to the size of a walnut or even larger. On section it exhibits the well known grey, moist, vascular tissue of the pineal gland, and in old persons a large number of the sand-like bodies are rarely absent. Histologically, the cell elements are somewhat larger and firmer than in the normal gland. These tumours produce pressure on the cor- pora quadrigemina and venae magnae Galeni, and that on the latter in its turn may give rise to secondary hydrocephalus. (3) Myxoma is rarer in the brain than in the spinal cord and peripheral I THE NATURE OF THE LESION. 555 nerves. It takes its origin, like glioma, from an overgrowth of the neuroglia, and extends uniformly in all directions by infiltration. (4) Solitary Tubercle, which is by far the most common tumour of the brain, is regarded by Rindfleisch as a product of the neuroglia, and as being allied to \he fibromata. They consist of hard nodules, varying in size from a pea to a pigeon's egg, and sometimes even larger, of grey, yellow, or yellowish- white colour and globular form. On section the interior of the nodule is yellowish and cheesy, while the outer cortex is of a reddish- grey colour, and very vascular. The thickness of the cortical layer is inversely proportional to the size of the tumour ; in a tumom- the size of a hazel-nut which I saw lately it was a line in thickness, and in another of the size of a walnut it was not much thicker than brown paper. The cortical tissue is continuous with the cheesy nodule on the one side and with the healthy brain matter on the other. These tumours are met with in all parts of the brain and cord, but their favourite seat is the cortical substance of the cerebrum and cerebellum, close upon the cortico-medullary boundary. This tumour is frequently multiple, and then each nodule is usually small ; but when there is only one tumour it may attain a con- siderable size. Eindfleisch distinguishes a tubercular and a non- tubercular variety of the solitary cheesy nodule. In the non-tubercular variety the cortex of the nodule consists of a round-ceUed embryonic tissue, in which nothing peculiarly tubercular can be detected. The layer of nervous matter surrounding the nodule is also infiltrated with corpuscular elements, and thus the nodule increases steadily in size. Within the zone of proHferation there is found a large development of fibres between the corpuscular elements of the embryonic tissue, rendering it dense, while the cells are entirely replaced by fibres in the centre. The small cheesy nodules are usually mvdtiple, and prove on minute examination to be really tuberculous. The grey zone of proliferation which surrounds them is seen with the naked eye to consist of spherical nodules, each of which corresponds in shape and size to a miliary tubercle, while the interior of the nodule consists of tubercles which have under- gone the cheesy transformation. The young granules are continually pro- duced at the circumference, and the tumour grows by the constant addition of these. When the nodule has attained a considerable size, the process of growth stops, and a fibrous envelope gradually forms round the mass, so as to completely isolate it from the surrounding brain tissue, and this condition has led some pathologists to believe that all tubercles occur in an encysted condition in the brain. The centre of the nodule some- times softens, and occasionally the whole contents of an encysted tubercle may undergo this change. Very rarely the tubercular nodule has been fomid to have undergone a process of cretification. The cortex of the tumour consists of giant-cells, each being surroimded by lymphoid cells imbedded in a fibrillated reticulum. (5) Carcinomata. — Cancer of the brain frequently appears as fungus 556 FOCAL DISEASES, ACCOEDING TO haematodes of the dura mater. When it originates from the outer surface of the dm'a mater it forces its way along the vessels into the compact tissue of the bones, and ultimately perforates them, protruding as a fungoid tumour, and pushing the scalp before it. Simple cancer of the brain generally grows from the under surface of the pia mater, and even such tumours as appear to lie free in the substance of the brain are usually connected at some point or other with the pia mater lining an adjoining sulcus. Isolated tmnours, however, do exist, but they are always secondary. Cancer is one of the most frequent of in- tracranial tumours. It is generally primary, and, as a rule, remains long isolated. According to Lebert, out of 48 cases 45 were primary, and of these 13 exhibited simultaneously carcinoma of other organs. Primary cancer of the substance of the brain is generally single, but occasionally there is a symmetrical appearance of a tumour in corresponding parts on each side of the brain. Several tumours are generally found in the brain in the secondary form, but these are usually small. The smallest cancerous tumours are generally found embedded in the hemispheres of the brain, in the pons, base of the brain, and the medulla oblongata. Cancer rarely occurs in the medulla oblongata, crm-a, and corpora quad- rigemina, relatively more frequent in the optici thalami, corpora striata, and cerebellum. Cancerous tumours destroy the neighbouring tissues by pressure and infiltration. They are surrounded by a zone of softened tissue of about a line in breadth, in which active growth proceeds. The microscope dis- plays large cells rolled into nests, and crowded together in a matrix of fibres and blood-vessels. Many cancers, especially those connected with bone, exhibit a calcifi- cation of their stroma. The medullary forms undergo a cheesy meta- morphosis, which may lead to their being mistaken for tubercle of the brain. (6) Cholesteatoma, or pearl cancer, according to Rindfleisch, "combines the structure of an epitheUoma with the harmlessness of a wart or fibroid thickening." It appears to be derived from the pia mater, and is usually situated in some hollow at the base of the brain. It develops from iso- lated growths of the size of a mustard-seed, which blend to form masses of the size of a walnut. The tumour is enclosed by a delicate, indistinctly fibrous capsule ; it has an irregular form, and its siu-face presents a beau- tiful mother-of-pearl lustre. The tumour on section is hard, pearly, non- vascular, and composed of epidermic cells arranged in concentric layers, which have undergone partly homy and partly fatty transformation. These tumours grow very slowly, and consequently may remain for a long time without giving rise to symptoms, and they only excite irritation in the neighbouring tissues in the later stages. (7) Papilloma of the pia mater is occasionally met with ; and a second variety of this tumour, in which there is an abundant production of mucus from the surface of the papillse, is said by Eindfleisch to be frequently THE NATURE OF THE LESION, • 557 mistaken for myxoma, and he proposes to call this variety papilloma myxomatodes. (8) Syphilomata are usually found near the surface of the brain and develop from the perivascular sheaths. They may reach the size of a walnut or even a hen's egg. In their interior there are usually several cheesy patches, while the circumference is made up of soft jelly-like and very vascular tissue. Syphilitic gummata are made up of highly cellular embryonic tissue, with an abundant mucoid basis-substance, the cells being concentrically arranged round the vessels. Other signs of the syj)hilitic dyscrasia are generally found at the autopsy. (9) Sarcomata occur in all varieties in the brain, and grow from the free surfaces of the interstitial spaces. They appear as hard, slightly vascular, round, somewhat nodulated tumours. The soft, cellular sarcomata present many transitions to other forms of tumour indicated by the names glio-sarcoma, myxo-sarcoma, &c. One form of spindle-cell sarcoma grows by preference from the dura mater at the base of the brain, forming tuberculated masses near the sella Turcica, and compressing the adjacent parts of the brain and the cranial nerves at their points of exit. In some sarcomatous tumours the spindle-cells are arranged in concentric layers forming nests. This form has been named " nested sarcoma" by Dr. Gowers. (10) Lipoma has occasionally been met with on the inner surface of . the dura mater and on the ventricular ependyma. (11) Psammomum is a tumour with a basis of connective or sometimes of mucoid tissue, distinguished by its containing calcareous concretions. It usually grows from the membranes of the brain, and especially from the choroid plexus, in which situation it often contains numerous cysts. According to the most recent investigations psammomum is to be regarded, not as a distinct kind of tumour, but as a calcareous deposit in tumours of widely different structure (Dreschfeld). (12) Osteomaia. — If we exclude the calcifications of other tumours, true formations of bone are the rarest of all intracranial growths. Osseous formations in the dura mater, after injuries, are more common. Syphilitic exostoses, although for the most part arising from the external table, yet sometimes spring from the internal surface of the skull, and cause pres- sure on the brain like other tumours in the same locality. (13) Cystic growths in the brain are not so common as was formerly supposed. They are most common in the pituitary body. (14) Angiom,ata generally occur in the brain as a complication of other tumours, such as glioma. The growths on the inner surface of the dm-a mater, described under the name of pachymeningitis haemorrhagica breg- matica, belong to this class. (6) Aneurisms. Aneurisms of the cerebral arteries are not rare. They are of various sizes, but only those which arise from the larger vessels, chiefly at the 558 ' FOCAL DISEASES, ACCORDING TO base of the brain, will come under consideration at present. They gene- rally arise in consequence of atheromatous degeneration of the vessels. The common termination is in rupture. (c) Parasites of the Brain. The animal parasites which occur in the cranial cavity are (]) Cysti- cercus cellulosae, and (2) Echinococcus hominis. (1) Cysticercus CeUulosce. — Cysticerci of the brain generally occur, according to Eosenthal, in the parts which are richly supplied by vessels, such as the ventricles, the ganglia and their commissures, the pia mater, and the cortex of the brain. They were found 23 times in the meninges, especially the pia mater, 59 times in the cortex, 32 times in the basal ganglia and adjacent commissures, 18 times in the ventricles, 18 times in the cerebellum, 4 times in the pons, and twice in the medulla oblongata (Rosenthal). The parasite is sometimes found in other parts of the body as well as in the brain. Out of 88 cases collected by Kuechenmeister, the cysticerci were found 1 1 times in other parts of the body. Cerebral cysticerci are usually enclosed in a soft capsule, in which the animal may be seen with the naked eye as a small white tubercle ; while its neck, with the characteristic booklets, may be discovered on microscopic examination. Cerebral cysticerci occur with greatest frequency in places where cows pasture in fields strewn with the excrement collected in cities (Cobbold). (2) Echinococcus Hominis. — Echinococcus cysts often reach a large size. In a case reported by Dr. Morgan, the cyst was as large as a walnut, and weighed 647 grammes. Of forty observations collected by Dr. Morgan, the cyst was situated 10 times in the cerebral lobes, 8 times in the cere- bellum, 4 times in the ventricles, twice in the ventricles, and once in the pons. The cysts attain their greatest size in the hemispheres, and in the lateral ventricles, especially in children before the fontanelles are closed. The cyst is composed of an external fibrous membrane which encloses the parasites ; its internal surface is lined by small buds, each about the size of a millet seed, and provided with the characteristic ring of booklets. The cavity of the cyst is usually filled with a liquid, which is either clear or contains floating debris and secondary vesicles, the buds of the latter being destitute of hooks, and called acephalocyst. § 733. Morbid Physiology. — The only part of the physiology of cerebral tumours with which we are here concerned is to connect the symptoms with the effects produced by the growth upon the nervous tissues. The tumour grows from a minute point, and gradually increases in circumference, so that it is at first almost entirely latent, or only gives rise to indefinite symptoms. As the tumour increases in size it pro- duces progressive general compression of the whole brain. In THE NATURE OF THE LESION. , 559 order to make room for the increasing size of the tumour, the cerebro-spinal fluid is first removed, the blood is then squeezed out of the vessels, and the whole substance of the brain suffers pressure. It is evident, therefore, that a process of this nature will ultimately lead to gradual abolition of the functions of the brain. But not only is the brain subjected to general compression, but the tissues surrounding the new growth are liable to special pressure, which soon leads to their destruction. The tumour itself must probably always be regarded as a destroying lesion, and consequently its direct tendency, as a local growth, is to give rise to depressive symptoms. It must, however, be remem- bered that the abolition of the function of a higher centre may leave the functional activity of a lower centre more unre- strained. But although the direct tendency of the tumour is to destroy the surrounding tissues, yet its indirect effect is often irritative. The tumour acts as a foreign body, and is liable to cause hyper- 83mia and inflammation of the surrounding tissues. Intercurrent attacks of irritative symptoms are therefore very liable to take place in the course of cerebral tumour, but they are generally followed by a further extension of those of depression. It must also be remembered that irritation of a higher centre may pro- duce an inhibitory action on a lower centre. But the processes set up in the surrounding tissues are not always of an irritative or inflammatory nature. An artery may be compressed and the tissues to which it is distributed may undergo ischsemic softening. The veins in the vicinity of the tumour may be compressed, giving rise to effusion of serum either into the sur- rounding tissues or into the ventricles of the brain. Softening as well as oedema of the surrounding tissues, in whatever way produced, must be regarded as a destroying lesion, and the symptoms depend upon the situation and not the nature of the lesion. § 734. Grouping of the Symptoms. — A review of the symp- toms of intracranial tumours shows that, although they are very numerous and variable, they admit for practical purposes of the following arrangement: — (1) General and initial symp- 560 FOCAL DISEASES, ACCORDING TO toms, which may be present in every kind of intracranial tumour, whatever its position ; (2) Symptoms caused by the localisation of the lesion ; (3) Intercurrent symptoms depend- ing on accessory lesions ; (4) Terminal phenomena. (1) Th^ general and initial symptoms consist of headache, dizziness, restlessness, and mental irritability, parsesthesise, various disturbances of the special senses, and convulsions. These symptoms may be present individually or in various combinations, and for a long time they may be the only symptoms complained of. (2) The symptoms which depend upon the localisation of the tumour do not differ essentially from the symptoms caused by other focal diseases of the brain. They result from destruction of the surrounding parts of the brain ; they are essentially paralytic in their character, although the loss of function may occasionally be preceded by transitory irritative phe- nomena. -These symptoms will be more fully described heieafter. (3) The accessory lesions which give rise to intercurrent symptoms are hypersemia and inflammation of the surrounding tissues. The chief symptoms caused by these lesions are hallucinations, maniacal and con- vulsive paroxysms, and attacks of apoplexy and meningitis. (4) The terminal symptoms are caused by gradual and increasing compression of the brain, and consist of the progressive abohtion of the mental faculties, and general sensory and motor paralysis, ending in coma. In many cases of cerebral tumours death results from an intercurrent disease, from an attack of cerebral hsemorrhage, or from sudden paralysis of the respiratory centre when the tumour is situated in the pons or upper end of the medulla, or when the ventricles are distended with serum. The intensity of the symptoms is by no means proportional to the size of the tumour, inasmuch as a growth may sometimes attain a large size without giving rise to marked symptoms, while at other times a small- sized tumour may give rise to intense disturbances. The following are the conditions on which the differences in the in- tensity of the symptoms appear to depend : — (a) Idiosyncrasies of the patient ; {b) the position of the tumour ; (c) the nature and rate of growth of the tumour ; {d) the changes set up in the surrounding tissues ; and (e) the presence of several tumours, or the existence of complications. (a) Idiosyncrasies of the Patient. — It is well known that some men react much more actively than others to the same degree of irritation. A degree of irritation, for instance, which would not produce an appreciable effect on adults may occasion violent convulsions in children. (6) Position of the Tumour. — Some parts of the brain are tolerant and others are very intolerant of displacement or any interference from without. The white substance of the hemispheres and the occipital lobes belong to the first category ; the medulla, pons, and the internal capsule of the lenticular nucleus to the second. THE NATURE OF THE LESION. 561 (c) Nature, of the Tumoxir and its Rate of Growth. —It may be laid doM'ii as a general rule that the intensity of the symptoms is in direct pro- portion to the rapidity of the growth of the tumoiu". The slow-growing cholesteatomata, for instance, usually attain a considerable size before giving rise to any distinctive symptoms. When the gro-wi;h is rapid there is a greater flow of blood to the part, and the surrounding tissues are more liable to undergo irritative changes, while the brain has no time to accom- modate itself to the new disturbance. The increased bulk of the tumour is sometimes caused not by growth of its tissue elements, but by oedema or haemorrhage, and then it produces all the effects of a sudden injury to the brain. Conducting fibres which, if pushed aside by a slow-growing tumour, would maintain for a long time their fimctional integrity, are now suddenly stretched, ruptured, and irremediably damaged. Retrogressive changes within the tmnoiirs may, according to their nature, cause great variations in the symptoms. Sometimes these changes may lead to haemor- rhage and all its consequences ; while at other times the tumoiu- may by these changes become diminished in bulk, thus relieving the pressure on the brain and leading to a temporary amelioration of the symptoms. {d) Morbid Changes in the Surrounding Tissues. — The changes set up in the tissues surrounding the tvmioiu- may either constitute discharging or destroying lesions. It is not possible to draw a clear line of demarcation between these two kinds so far as the symptoms are concerned, since the effect of a destroying lesion in the immediate vicinity of the tumour may, be obscured by those of discharging lesions in remote parts. In the early stages of the growth of the tumour the discharging lesions predominate. The tumour acts as a mechanical irritant or' foreign body, and it may directly irritate the part in which it is situated, or indirectly irritate remote parts by reflex action, or again its effects may be more or less diffused and general. It is very important to observe that the symptoms of intracranial tumours frequently intermit in the early stages of the disease, and only become permanent and continuous in the latter stages when the whole brain is subjected to pressure. The reasons for this intermittence of symptoms are riot far to seek. A large discharge of nervous energy is followed by exhaustion, so that the discharging lesions caused by the local irritation of the tiunours are followed by exhaustion, accompanied by tem- porary subsidence of the active symptoms. At other times the symptoms may be caused not so much by the size of the tumour as by oedema and inflammation of the surrounding tissues, and when the latter subside the symptoms disappear for a time, although the primary lesion still persists. (e) The Presence of several Tumours and Complications. — The variety and complication of symptoms are very much increased when several tumours are present, or when symptoms of tumour are associated with cerebral disturbance caused by an independent affection, such as Bright's disease. • KK 562 FOCAL DISEASES, ACCORDING TO § 735, Diagnosis. — Intracranial tumours may be confounded with other cerebral lesions, and indeed at an early stage it is almost impossible to be sure of the diagnosis. The most important symptom of tumour is to be found in the optic discs. Many cases are recorded in which the presence of double optic neuritis was the only symptom that could lead one to the suspicion of cerebral tumour, and in which the diagnosis was subsequently justified by the progress of the case. Two cases of this kind have come under my own observation, and the occurrence of such cases has led Dr. Hughlings-Jackson to insist on the routine use of the ophthalmoscope in the examination of patients. In tubercle the disease of the brain is generally associated with tuberculous affections of other organs, and a hereditary predisposition to the disease can usually be ascertained. Hydrocephalus, in its chronic form, is a frequent accompa- niment of tumour, especially when the latter is situated under the tentorium, where the growth is liable to produce pressure on the venae Galeni magnse, or to prevent the return of the cerebro-spinal fluid into the spinal canal. Apoplexy occurs in advanced age, its onset is sudden, and it is usually associated with disease of the heart, atheroma of the vessels, and granular kidney ; while the paralysis is sudden, without premonitory symptoms, and frequently followed by late rigidity in the extremities. Tumour, on the other hand, occurs at every time of life without being necessarily associated with other diseases, while the paralysis comes on slowly and increases gradually, and is preceded by other symptoms, such as violent cephalalgia, vomiting, vertigo, and neuralgia, and it is rarely followed by late rigidity. They may be further dis- tinguished from each other by the double optic neuritis of cerebral tumour, in opposition to the rarer unilateral embolic amaurosis of apoplexy. Care, however, must be taken not to confound one form of albuminuric retinitis with the optic neuritis of cerebral tumour. In chronic softening the paroxysms of headache are less fre- quent and intense than in tumour, while affections of the special senses and ansesthesia of the cephalic nerves occur more fre- quently in tumour than in softening ; on the other hand the THE NATURE OF THE LESION. 563 occurrence of sudden and complete hemiplegia and aphasia is more common in softening than in tumour. Alternate and bilateral paralysis occur, according to Hasse, frequently in tumour and only exceptionally in softening. Abscess of the brain is to some extent similar to tumour in its physical relations, inasmuch as it may produce increase of intracranial pressure, and, like tumour, the tissues surrounding the diseased focus are often affected by inflammatory attacks. Abscess usually occurs as the direct consequence of an injury, such as fractures of the skull and concussions of the brain, or associated with some other disease, such as caries of the petrous portion of the temporal bone, ozsena, foci of suppuration, diseased vessels, or valvular diseases of the heart; while tumour is never more than a remote consequence of an injury. In tumour the cephalalgia is severe, the various symptoms assume a progressive character, and there is usually a gradual extinction of the functions of the brain; or apoplexy may occur, but meningitis is rare. Atrophy of the brain produces an early destruction of the mental activities which passes gradually into imbecility. The presence of tremors of the lips, tongue, and limbs, of epilepti- form convulsions, hemiplegia or paraplegia, and loss of mental power, form a group of symptoms so characteristic that they cannot well be mistaken for those of tumour. Hypertrophy of the brain of children gives rise to symptoms as cephalalgia and epileptiform convulsions somewhat similar to those of tumour. The large circumference of the great fontanelle, with its strong pulsation, the slow dilatation of the head, the distinct traces of rickets in the skeleton, and spasms of the larynx combine to prevent this disease from being mistaken for cerebral tumour. Syphilis of the brain may give rise to symptoms closely simulating those of cerebral tumour, and indeed the presence of a distinct gumma induces symptoms which are identical with the symptoms of other forms of tumour. The history of the case, permanent traces of the disease such as cicatrices, the peculiar pains of the nerves and bones, epileptiform convulsions, and evidences of the presence of more than one focus of disease, are amongst the signs to be made use of in forming a diagnosis. 564 FOCAL DISEASES, ACCORDING TO § 786. Diagnosis of the nature of the Tumour. — It is not always possible to diagnose the nature of the tumour, although this may be done sometimes with a considerable degree of cer- tainty. The development of glioma is frequently preceded by an injury to the skull, the progress of the symptoms is slow, and the illness is consequently of comparatively long duration. Hsemorrhage not unfrequently occurs into the substance of the tumour or into the surrounding tissues, and the patient is, therefore, liable to suffer from intercurrent attacks of apoplexy. Tiirbercular tumour may be suspected when the symptoms of intracranial tumour occur in childhood, and when a heredi- tary predisposition to tubercle can be traced. The diagnosis is rendered more certain when evidence of tuberculosis in other organs or cheesy degeneration of the glands can be detected. The tumour is also more likely to be of a tubercular nature when the symptoms indicate that it is situated in the cere- bellum, or that multiple lesions are present. Tubercular tumour often begins after an acute febrile disease, as measles or scarlet fever, while its progress is frequently complicated by slight attacks of meningitis. Carcinoma of the brain is characterised by the rapid pro- gress of the symptoms, and the presence of the cancerous cachexia or evidence of the deposition of cancer in other organs. Sarcom,ata are not easily diagnosticated during life, but when the most prominent symptoms are afforded by compression of the nerves at the base of the brain sarcoma may be suspected. Syphilomata of the brain will be subsequently described in detail. Cysticercus cellulosce, when situated in the brain, often re- mains latent for a comparatively long period. The more usual symptoms of the affection are headache and vertigo, followed by muscular spasms, epileptiform convulsions, and various mental disturbances, but distinct paralysis is rare. The con- vulsions caused by the presence of the parasite may at first be similar in every respect to those of idiopathic epilepsy, but in the terminal period the attacks increase in number and violence, as many as 80 to 100 daily having been known to occur during the week previous to death (Rosenthal). The psychical disturbances consist at first of illusions, delirium, THE NATURE OF THE LESION. 565 maniacal attacks, followed by melancholy, somnolency, and stupor. The diagnosis of the presence of cysticerci is rendered more probable if, in addition to the symptoms just described, the history of the case show that the patient had previously suffered from taenia, or if the patient be a butcher or pork dealer. Echinococcus hominis, when found in the brain, does not give rise to characteristic symptoms. The most constant symp- toms are headache, vertigo, vomiting, tremors, epileptiform attacks, and the usual evidences of the presence of an intra- cranial tumour in the optic discs. In the cases collected by Dr. Morgan the duration of the symptoms averaged one and a half years. The tumour may sometimes make its way through the cranial bones. In Reeb's case it made its way through the parietal bone, while in a case observed by Westphal two openings were found in the frontal bone through which the tumour projected ; an incision having been made 90 vesicles flowed through the opening, and the case terminated in recovery. Westphal states that the diagnosis of the presence of echino- cocci in the brain must be made from the general symptoms of intracranial tumour appearing and disappearing alternately, oedema of the eyelids, an opening in the cranial bones through which a fluctuating tumour projects, or exploratory puncture. Aneurism of the cerebral arteries gives rise to symptoms like those of other tumours situated at the base of the brain, nor are there any sure signs by means of which the former may be distinguished from the latter. Even auscultation of the skull has not hitherto proved of much use in the diagnosis of intra- cranial aneurism. If aneurism of any of the other vessels of the body co-exist with the symptoms of tumour situated at the base of the skull, then aneurism of one of the cerebral vessels may be suspected. It is probable that aneurism gives rise to more pronounced symptoms of irritation, such as intense cepha- lalgia, paroxysms of severe and intractable trifacial neuralgia, attacks of mania and other grave psychical disorders, than solid growths. If a patient, who has been suffering from the symptoms of tumour situated at the base of the brain, die suddenly from an attack of ingravescent apoplexy, it may be conjectured that the tumour was an aneurism rather than a 566 FOCAL DISEASES, ACCORDING TO new formation. If a case, in which the patient has suffered from the symptoms of tumour situated in the anterior fossa of the skull, terminate fatally from a copious haemorrhage from the nose, it may be assumed with considerable probability that an aneurism of the anterior cerebral artery has perforated the cribriform plate of the ethnoid bone. If pulsation and a mur- mur on auscultation be observed in the orbit immediately after an injury to the skull, it is probable that a communication has been established between the internal carotid artery and the cavernous sinus (Lebert). § 737. Prognosis. — With the exception of syphilitic cases, death is the usual consequence of cerebral tumours. Even a syphilitic tumour may not be amenable to treatment if it be of long standing, since irreparable mischief to the brain may have already been caused by it. Cases of cerebral tumour may some- times terminate in sudden death through an attack of apoplexy or of convulsions, or occasionally without evident cause. In other cases the symptoms may become quiescent, the vomiting cease, the amaurosis even disappear, and the patient regard himself cured. After a time, however, the symptoms usually recur with increased intensity, and lead to a fatal termination. § 738. TreatTiient. — In the large majority of cases very little can be done by treatment, but even in these unpromising cases curative efforts should not be abandoned. In the earlier stages of cerebral tumours the symptoms are generally those of irritation and of local congestion, and these must be treated by cold to the head, purgatives, and occasionally by the use of flying blisters. The cephalalgia may be combated by ice to the head, and if no relief be afforded, narcotics are to be cautiously resorted to. Subcutaneous injections of morphia will be found the most useful and reliable remedy, although small doses of belladonna have occasionally been attended with benefit. The chloride of ammonium may occasionally be found useful. When convulsions are a prominent symptom, doses of from half a drachm to a drachm of the bromide of potassium may be useful. THE NATURE OF THE LESION. 567 With the view of promoting absorption of the morbid growth, iodide of potassium has been administered in large doses and with apparent benefit. For adults half-drachm doses may be given to begin with, and increased until a drachm is taken three times a day. Of course if there be evidence of syphilis, energetic anti-syphilitic treatment by means of mercury and iodide of potassium is indicated. 568 CHAPTER VI. (II.) SPECIAL CONSIDERATION OF FOCAL DISEASES, ACCORDING TO THE LOCALISATION OF THE LESION. 1. AFFECTIONS OF THE PEDUNCULAR FIBRES AND INTERNAL CAPSULE. a. Affections of the Pyramidal Tract. (i.) Hemiplegia. § 739. Hemiplegia consists of paralysis of one-half of the body, although many of the muscles are either not implicated or only temporarily weakened. The paralysis is, as a rule, limited to the arm, leg, and part of the face. In facial paralysis of cerebral origin the cheek on the affected side looks flat, the corresponding naso-labial fold is obliterated, the upper lip is less arched, and the angle of the mouth is lowered on the affected side, the distortion becoming more marked when the facial muscles of the healthy side contract. Paralysis of the orbicularis oris interferes with the pronunciation of the labials and with such actions as whistling and blowing out a candle. The patient can frown as usual, raise his eye- brow and eyelid and close his eye on the paralysed almost as well as on the healthy side, but is unable to perform a uni- lateral action like winking on the affected side. The facial paralysis begins usually to disappear in a few weeks, and some- times in a few days, while it may persist for months. The muscles chiefly affected in facial paralysis of cerebral origin are the buccinator, orbicularis oris, and the straight muscles which pass to the angle of the mouth and to the nose on the paralysed side; while the occipito-fron talis, corrugator super- FOCAL DISEASES. 569 cilii, and orbicularis oculi remain almost entirely unaffected. In facial paralysis of peripheral origin all the muscles supplied by the facial nerve below the lesion are equally paralysed. The hypoglossal nerve is affected in most cases of apoplexy, as shown by a certain degree of difficulty in executing the movements of the tongue. On protrusion its point deviates more or less to the paralysed side, the base being dragged further forwards on the healthy side. The affection of the tongue, as a rule, disappears in a short time, but is occasionally permanent. Some observers state that the muscles of the trunk are un- affected in hemiplegia, but the inspiratory muscles undoubtedly act less freely on the paralysed side for the first few days in severe cases. (ii.) Hemispasm. § 740. The spasms which occur in connection with focal cerebral lesions are of three kinds : (a) Tonic, (b) combined tonic and clonic, and (c) clonic spasms. (a) Tonic Spasms. — The tonic contractions which occur in connection Avith focal lesions of the brain may be divided into two classes : (i.) Early and (ii.) late rigidity. (i.) Early Rigidity. — The contractions which occur in early- rigidity may be subdivided into those which immediately ac- company the haemorrhage, and those which occur a few days after the attack. The contractions of the first kind are probably produced by irritation of the fibres of the pyramidal tract, occasioned either by rupture or partial injury. The second form of early rigidity appears in the paralysed parts a few days after the occurrence of hsemorrhage, and during the time inflammatory changes are taking place in the tissues sur- rounding the clot. These contractions, therefore, are probably also the result of irritation of the fibres of the pyramidal tract. Early rigidity may be so slight as only to be manifest when passive movement of the paralysed extremity is made. When the arm is flexed, for instance, if an attempt be made to straighten it, the biceps offers resistance to the movement; while at other times resistance is offered to flexion by con- traction of the triceps. 570 FOCAL DISEASES, ACCORDING TO The rigidity may sometimes be limited to the fingers, while at other times the arm is drawn to the side of the chest, the elbow and wrist are firmly bent, the fingers are flexed upon the palm, and all attempts to extend the limb increase the con- tractions, and cause pain as well as some amount of tremor or slight clonic spasm. The resistance yields occasionally under steady pressure. This form of rigidity may affect the leg as well as the arm, and then the thigh becomes flexed on the trunk, and the leg on the thigh, so that the heel is brought up to the buttock. Early rigidity generally disappears soon, but may persist for weeks or months. The affected muscles do not undergo atrophy, their faradic and reflex excitability is increased, and they become completely relaxed during sleep, although the spasm recurs immediately on the patient awaking. The appearance of early rigidity diminishes the chances of the patient's recovery, and when it continues for a long time changes take place in the muscles, tendons, and joints of the affected extremities, which ultimately leave them permanently contracted and useless. (ii.) Late Rigidity. — This form of contracture is caused by descending degeneration of the fibres of the pyramidal tract, and corresponds in its essential character to the spasmodic rigidity of primary lateral sclerosis. Its most characteristic feature is the exaggeration of the tendinous and periosteal reflexes. When the lower extremity is affected the patellar- reflex is in excess, and ankle-clonus is readily elicited, and corresponding phenomena may be obtained in the upper ex- tremity when it becomes the subject of contracture. When the loss of voluntary power is complete, the rigidity is more or less constant, although it is in most cases diminished during sleep and increased during voluntary efforts and emotional disturbances. The attitudes assumed by the limbs affected with late rigidity differ considerably in different cases, but on the whole they conform to the rule observed in almost all spasmodic affections, namely, that flexion predominates in the upper, and extension in the lower extremity. In the most usual attitude of the upper extremity the arm is drawn towards the trunk by contraction of the pectoralis major. The forearm is semi-flexed f .V ( •I 'i i THE LOCALISATION OF THE LESION. 571 on the arm and pronated, the hand is slightly flexed on the forearm, and the fingers are closed. In some cases the forearm, instead of being semi-flexed and pronated, is semi-flexed and supinated. In a few rare cases the forearm is extended upon the arm, and then the forearm may either be in a state of supination or pronation (Charcot). Probably the most frequent attitude of the hand is that in which the fingers are ex- tended at the metacarpo-phalangeal and flexed at the phalangeal joints (Gowers). The inferior extremity is, as a rule, main- tained in a state of rigid extension, the foot being in the posi- tion of talipes equino-varus. In some few cases flexion pre- dominates over extension in the lower extremity, and then the thigh becomes flexed on the trunk, and the legs on the thigh, so that the heel touches the buttock. In these cases the con- tracture is apt to extend to the opposite extremity, and then station and locomotion are impossible. In some cases the con- tracture extends to the inferior muscles of the face. The con- tracture is at first transitory, and only manifested when the patient laughs or cries, but after a time it becomes permanent. The angle of the mouth on the affected side is then elevated, the naso-labial fold is increased in depth, and even the eye of the corresponding side may be smaller than the healthy eye (Plate VI, 2, 3, and 4). After a time, however, the muscles may undergo progressive atrophy, and the contractures almost entirely disappear, although the bones and ligaments having become adapted to the form in which the limb has so long been maintained the deformity persists. In these cases it is probable that the descending degeneration of the lateral column of the spinal cord has ex- tended to the ganglion cells of the anterior grey horns. The muscles which do not suffer at all, or suffer least, from late rigidity are those that are bilaterally associated in their actions, while those acting independently of the corresponding muscles of the other side are most affected. In accordance with this rule, the muscles of the trunk remain unaffected, and the muscles of the lower extremity are less frequently and less profoundly affected than those of the upper ; the superior muscles of the face generally escape, while the inferior facial muscles are occasion- ally attacked. The rigidity, however, is not always so fixed and 572 FOCAL DISEASES, ACCORDING TO unvarying as that just described. It may never become fully established, or after having become established may undergo a considerable amount of improvement. When the rigidity has never been fully established, it may be observed that the tension becomes less when the limb is warm and greater when it is cold ; that it can be diminished by gently rubbing the muscles ; and that it disappears almost, if not entirely, during sleep. On the other hand, the rigidity is increased during voluntary efforts to move the limb, this effect being more marked when the patient is under observation. Although rigidity may have become fully established, at the end of some months it gradually diminishes to such a degree that Brissaud proposes to call the condition latent contracture. The patient may perform all the simple movements of the limb, and probably with undiminished power, but whenever his atten- tion is specially directed to the movements, as when he wishes to perform any manual operation requiring a little dexterity, the muscles instantly become rigid, the fingers are flexed on the palm, and the deformity which was present during the period of fixed contracture reappears. It may also be shown that the tendon reflexes continue exaggerated, although the muscular tension has in great part disappeared. It is not 3^et ascertained whether the disappearance of the muscular tension is due to a corresponding repair of the fibres of the injured pyramidal tract on the opposite side, or to the establishment of new connections with the cortex of the brain on the same side through commissural fibres in the cord. (6) Combined Tonic and Clonic Spasms. — The cases just described, in which a slight degree of muscular tension per- manently present in the affected extremity is associated with marked spasm on a voluntary effort being made to move the limb, form a fitting transition to those cases in which a fixed tonic contraction of some of the muscles is associated with clonic contractions of others. In the combined tonic and clonic varieties of post-hemiplegic motor disorders, the muscular con- tractions are at first entirely like those which occur in late rigidity, but after a time some of the muscles implicated become the subjects of clonic spasm. Varieties. — The combined tonic and clonic spasms of hemi- THE LOCALISATION OF THE LESION. 573 plegic limbs consist of the following varieties : — (i.) Intermittent tremor, and (ii.) Choreiform movements. (i.) Intermittent Tremor. — The most usual form of tremor observed in hemiplegia limbs corresponds with that which is observed in spastic spinal paralysis. The tendon reflexes are exaggerated, and the tremor is induced when the muscles are put upon the stretch by any attempt at voluntary movement or otherwise. This kind of tremor is therefore similar to that described as " spinal epilepsy " in lateral sclerosis of the spinal cord, and, like the latter, it is associated with descending sclerosis of the pyramidal tract. The tremor is, like that of multiple sclerosis, absent during repose. The muscles of hemiplegic limbs are liable to be affected with fibrillary contractions similar to those which occur in progressive muscular atrophy and amyotrophic lateral sclerosis. It is probable that muscular atrophy is always associated with these contractions in hemiplegia, and that the descendiug changes of the pyramidal tract have extended to the ganglion cells of the anterior grey horns of the cord. (ii.) GhoreiforTn Movements. — Clonic choreiform spasms of the extremities may either precede or follow an attack of hemi- plegia, the former being named pre-hemiplegic, and the latter post- hemiplegic chorea (Weir Mitchell, Charcot). In pre- hemiplegic chorea the patient complains of a feeling of numb- ness and feebleness of the extremities of one side, his gait becomes hesitating and irregular, and the upper extremity of the affected side is attaked by choreiform movements.- These- symptoms may continue for some days, when complete hemi- plegia, usually associated with hemiansesthesia, is either sud- denly or gradually established. Post-hemiplegic chorea occurs in partially but never in completely paralysed limbs, and Usually appears simultaneously with a marked diminution of the para- lytic symptoms. The clonic spasms as a rule become gradually established as motor power returns, although they sometimes supervene suddenly, and appear to be sometimes induced by a strenuous voluntary effort on the part of the patient to move the paralysed limb. Clonic spasms occur more frequently in the arm than in the leg, and when they exist in both they are more severe in the former, while if the leg be exclusively affected' 574 FOCAL DISEASES, ACCORDING TO the arm is usually completely paralysed. The muscles of the face are sometimes affected by those spasms, causing various distortions, which become greatly increased when the patient laughs or cries. The movements affected by choreiform spasm in the upper extremity are, in decreasing order of frequency, the special movements of the fingers and thumb, flexion and extension of the wrist, pronation and supination of the forearm, extension and flexion at the elbow, and movements at the shoulder-joint. The iuterossei are particulary liable to be affected by chorei- form spasm, and consequently the movements most frequently observed consist of varying degrees of flexion and extension at the metacarpo-phalangeal articulations, associated respectively with extension and flexion at the phalangeal articulations. The movements induced by these spasms are of wider range than those of hemiplegic tremor, resembling in this respect the movements of chorea. They are disorderly and irregular, and may or may not continue during complete repose ; they cease during sleep, and become much aggravated during voluntary efforts to perform a definite movement with the affected limb, such as that of raising a glass of water to the mouth. When the lower extremity is affected, the whole body may be thrown into a state of agitation during locomotion. Two forms of jpost-henni'plegic chorea may be distinguished : (a) the post-hemiplegic chorea of adults ; and (^) the spastic hemiplegic of infancy. The spastic hemiplegia of infancy may consist of a purely tonic spasm of the muscles without any admixture of clonic spasms, although the choreiform variety is probably the more common. (a) Post-hemiplegic Chorea of Adults. — The post-hemiplegic chorea of adults and the corresponding affection of infancy differ iu various ways. In the former the history of the case shows that the attack of hemiplegia which preceded the appearance of the clonic spasms occurred during adult life, or at any rate not in early mfancy. The attack of hemiplegia may have occa- sionally become gradually established when due to the slow growth of a tumour, but as a rule it has come on suddenly with apoplectic symptoms. An examination of the patient may reveal valvular disease of the heart, or there may be a history THE LOCALISATION OF THE LESION. 575 of injury to the head. The post-hemiplegic chorea of adults, apart from the history, differs from that of infancy in the co- existence of hemianaesthesia in the former and its absence in the latter. The ansesthesia extends over the lateral half of the body ; and all forms of sensibility, including the special senses, are more or less affected. Three distinct cases of the post- hemiplegic chorea of adults have come under my own obser- vation. All the patients were comparatively young men, their ages ranging from 25 to 33 years. The attack of hemiplegia, which had preceded the choreiform movements, occurred in each several years previously to my seeing them. Two of the patients presented evidence of slight stenosis of the mitral valve, and in the third the apoplectic attack had been induced by a fall on the head. The attitude assumed by the affected arm was very similar in the three cases. There was marked tonic spasm of the posterior third of the deltoid in all of them, so that the elbow was abducted from the trunk to the extent of about two and a half inches, while it was also drawn backwards considerably behind the posterior plane of the body. The fore- arm was slightly flexed on the arm and strongly pronated, the hand was slightly flexed on the forearm, while the fingers were kept in constant movement by clonic spasms of the interossei muscles. There was also a certain degree of spasmodic pro- nation and supination of the forearm and flexion and extension of the hand in all; while in one, irregular jerking movements of the forearm, hand, and fingers occurred when the patient attempted to grasp any object with the paralysed hand. A marked feature presented by these cases was the fact that each patient carried the affected hand in the out pocket of his coat, in order to arrest its disorderly movements. In this position the upper arm was directed downwards, outwards, and back- wards from the shoulder, the elbow being considerably removed from the trunk and behind its posterior plane, the forearm was slightly bent on the arm, and the back of the hand was pressed closely against the hip. In the three patients referred to the tactile sensibility of the palm and fingers of the affected hand was remarkably deficient. When the patient was asked to close his hand on a coin placed on the palm, with his eyes closed, he could not say whether he 576 FOCAL DISEASES, ACCORDING TO had or had not the coin in his grasp ; and when the coin was withdrawn before the closure of the fingers, it was amusing to observe his puzzled expression on opening his eyes and hand when he found the latter empty. The patients could be pricked with a pin over half the face, trunk, and over extremities on the affected side almost without pain. In one of these cases all forms of cutaneous sensibility, and the muscular sense, were diminished over half of the body on the affected side, the senses of taste and smell were also diminished on the corresponding side, but the senses of hearing and sight were not affected to an appreciable extent, (/?) Spastic Hemiplegia of Infancy. — In the spastic hemi- plegia of infancy the lesion which determines the paralysis occurs during birth, or in early infancy. The paralysis appears sometimes to have become established before birth, but cases of this kind are exceptional. It is, however, not uncommon to ascertain, on inquiry from the parents, that the patient who is affected with the spastic hemiplegia of infancy suffered from repeated convulsions accompanied by uncon- sciousness for the first two or three days after birth, although it may not be observed that the child is paralysed on one half -of the body till some time subsequently. In the majority of these patients, however, the onset of the disease dates from the age of two to three months to that of four or five years. The most usual history is that after an illness of indefinite character ex- tending over a few days, or without any warning, the child has been taken with convulsions. These convulsions, as a rule, have recurred repeatedly for some hours or days, the child remaining in the meantime in a state of unconsciousness. In many cases this is the only history which can be obtained, but where the parents are intelligent it may be ascertained that the convulsions were limited to the side of the body which had subsequently become paralysed. Many infants doubtless die during these convulsions or a few days after, but in the cases which survive it is soon observed that one half of the body is paralysed. The hemiplegia in these cases pursues the usual course, contractures become established, and choreiform move- ments may or may not make their appearance during partial recovery, but when once these movements appear they remain THE LOCALISATION OF THE LESION. 577 permanent. So far, then, these cases present nothing peculiar except that the disease dates from childhood, that it is ushered in by convulsions and profound unconsciousness, and that the motor paralysis is not accompanied by hemiansesthesia. In the spastic hemiplegia of childhood, however, it is soon observed that the intellect of the patient, however bright the child may have been previous to the attacks of convulsions which marked the onset of the disease, has become markedly defective. This form of hemiplegia is, indeed, nearly always associated with some degree of idiocy. Another marked peculiarity of the affection is that at a cer- tain age the hemiplegia becomes associated with epilepsy. The epileptic attacks generally begin when the patient is from seven to fifteen years of age, and at first are usually limited to the paralysed side of the body, and may not be attended by decided loss of consciousness. In the case of a well-developed girl four- teen years of age, under my care, suffering from the spastic hemiplegia of childhood, the epileptic attacks began when she was eight years of age. The right half of the body was. paralysed, the arm being more paralysed than the leg, both limbs were somewhat rigid, but neither manifested any chorei- form movements. The epileptic attack always began by move- ments of the paralysed arm ; these soon extended to the muscles of the mouth on the same side, and then to the paralysed leg. In most attacks this patient became unconscious for a few moments, and then got up and walked about as if nothing had happened. In some, however, the convulsions were limited to the paralysed arm, with probably a slight exten- sion of them to the angle of the mouth, but the leg remained free, and there was no loss of consciousness. The patient was once reported by the nurse to have walked across the ward during an attack, holding down the convulsed and paralysed arm with the opposite hand. In old-established cases the con- vulsions may become general, but it may be observed that they retain a unilateral character at the commencement of the attack, and the patient usually describes a unilateral aura. The aura is often described as a sensation beginning in the paralysed hand, and ascending along the arm to the shoulder and head, when unconsciousness supervenes. At other times LL 578 FOCAL DISEASES, ACCORDING TO the sensation begins in the paralysed leg, and ascends succes- sively to the arm and head. In several cases under the care of Mr. Hardie, which I examined recently in Crumpsall Workhouse, three of which are represented in Plate VI., Figs. 2, 3, and 4, the patients could not give any account of an aura; and so far as I could judge from the account given by their attendants, the con- vulsions did not assume a unilateral character. In all these cases marked idiocy was present, so that the presence of an aura could not be determined from the inability of the patients to describe it. In one case of the kind, with choreiform move- ments of the paralysed hand, sent to me by Mr. CuUingworth, the patient had an epileptic attack once while I was examining her. I could not observe-that the convulsions assumed a pro- Dounced unilateral character at any time during the attack. On cross-examining her with respect to the aura, she positively denied that she had had any warning whatever of impending attacks; but after a time she volunteered the statement, " When the fits began first I used to have a creeping feeling in the leg, which came up to the arm," at the same time pointing successively to the paralysed leg and arm. These patients also present other phenomena which are worthy of notice, the most remarkable of which is an arrest of development of the paralysed limbs, generally implicating the corresponding side of the face. The circumference of the paralysed extremities is usually less than that of corresponding parts of the opposite limbs, although not always so. Where a limb is subject to violent choreiform movements, the muscles may become hypertrophied so that its circumference exceeds that of the corresponding healthy extremity. But even under these circumstances it may be found that the circumference of the bones on the affected side is less than that of the sound side, and that the enlargement is limited to the muscles. Each of the long bones of the affected extremities may be from ^in. to lin, shorter than the corresponding bones of the affected side, and even the clavicle of the paralysed side may be from |in. to ^in. shorter than the opposite clavicle. The diminution of size of half the face may extend to all the features, inclu- dmg the eyebrows, eyelids, half of the nose, the cheek, and half the mouth. THE LOCALISATION OF THE LESION. 579 (c) Clonic Spasms. — The post-hemiplegic motor disorders, which consist of clonic spasms unaccompanied by tonic con- tractions of the muscles, are (i.) continuous or remittent tremor, (ii.) choreiform movements (athetosis), and (iii.) jerking move- ments on voluntary effort (hemiataxia). (i.) Continuous or Remittent Tremor. — The tremor which has already been described as occurring in hemiplegic limbs was associated with increased muscular tension, excess of the tendon reflexes, and only occurred when a voluntary movement of the limb was made. In the form of tremor about to be described, muscular tension, if present in excess at all, is not a prominent feature of the case, the tendon reflexes are not exaggerated, the tremor is continuous at least during waking hours, and instead of being exaggerated it may be diminished or arrested by a voluntary effort. We have seen that the first form of tremor is like that which is observed in sclerosis in patches; while the second form is in all essential particulars like the tremors of paralysis agitans. A case of the latter kind has been described by Grasset. The tremors, which continued during repose, were accompanied by sensations of heat like those complained of by patients suffering from paralysis agitans. A case is described by Leyden in which tremors occurred in the right arm, momentarily arrested by a voluntary effort, while there was complete absence of any paralysis or contractures and of sensory disturbances. A round sarcomatous tumour was found in the left optic thalamus. By the courtesy of Dr. Leech, I had an opportunity of showing to the members of the British Medical Association at the Manchester meeting, a case in which one-half of the body presented all the characteristics of a moderately advanced paralysis agitans. The tremors extended to the right foot, leg, and one-half of the trunk; while the atti- tude of the forearm, fingers, and thumb was quite characteristic. The symptoms supervened nine months previously, and were preceded by a slight attack of confusion, not amounting to un- consciousness, followed by slight paresis of the right side of the body. (ii.) Athetosis. — An affection has been described by. Ham- mond under the name of athetosis, in which the patient is unable to maintain the fingers or toes in fixed positions. The 580 FOCAL DISEASES, ACCORDING TO fingers and toes in this affection are maintained in continuous slow movement, and are made to assume various distorted positions. These movements are not always limited to the fingers and toes, but extend to the hand and foot, and occasion- ally even to the muscles of the neck and face. No motor weakness has been recognised, the movements are only to a slight extent under the control of the will, they usually persist during sleep, and are not accompanied by contractures. Cases of the affection have been described by AUbutt, Currie Ritchie, Fisher (Boston, U.S.), Gairdner, and others, while Claye Shaw and Dreschfeld have drawn attention to the analagous condition sometimes observed in the limbs of imbecile children. Oulmont has written a valuable monograph of the whole subject. The appearance of the clonic spasm is in almost all cases preceded by a distinct attack of hemiplegia, and when no decided paralysis can be ascertained to have been present the history of the case shows that the patient has suffered from an attack of convulsions and unconsciousness. Hemiansesthesia is described as being present on the affected side in some of the reported cases, while a certain degree of numbness of the same side is frequently mentioned. In a con- siderable number of cases the condition of sensibility is not mentioned, and probably no special attention was directed to the point. The affected extremity usually presents vaso-motor disturb- ances. It is red or livid, moist, and colder than the corre- sponding extremity. The affected hand or foot is also frequently atrophied ; although the muscles which are affected by the spasm may undergo a certain amount of hypertrophy. The electric con- tractility of the affected muscles varies in different cases, being sometimes normal, at other times enfeebled or increased. Oulmont has observed an unusual degree of relaxation of the ligaments and joints of the affected extremities. A bilateral athetosis has been described by Oulmont. It does not differ essentially from the unilateral affection, except that the muscles of the face appear to be more liable to be im- plicated to a greater extent in the former. The bilateral affec- tion is generally associated with idiocy, but may occur without THE LOCALISATION OF THE LESION. 581 this complication. It is not, according to Oulmont, preceded by apoplexy or hemiplegia, and is unaccompanied by sensory disturbances. (iii.) Hemiataxia.—A case has been described by Dr. Gowers in which there was great inco-ordination of the right arm during voluntary movement, while there was complete absence of permanent rigidity and spontaneous spasm. The patient had suffered from a slight attack of apoplexy followed by hemi- plegia a year and a half before he came under observation, but the paralysis had disappeared, a slight weakness of the arm, leg, and face alone remaining. The ataxic movements of the arm became exaggerated on the eyes being closed. Tactile sensibility was diminished in the right arm, but sensibility to pain was normal. In a somewhat similar case recorded by the same observer the autopsy revealed "a puckered cicatrix" passing through the left thalamus from the one side to the other. A case in which ataxic movements occurred in the right hand is also described by Grasset. The patient had a series of apoplectic attacks followed by hemiplegia and a certain embarrassment of speech. The ataxic movements were limited to the right arm, the paralysis being more marked in the face and arm than in the leg. At the autopsy three centres of softening were found in the left hemisphere. The first occupied the region of the lenticulo-striate artery ; the second was in the optic thalamus close to its ventricular border ; and the third was found in the thalamus close to the posterior portion of the internal capsule. § 741. The Hemiplegic Walk — When the muscles of the paralysed lower extremity have acquired a certain degree of rigidity, the patient is able to walk by the aid of a stick, even if the voluntary paralysis of the affected side remain complete. The patient leans towards the healthy side, but is prevented from falling over to that side by the support of the stick ; the pelvis and hip-joint of the paralysed side are elevated by contraction of the abductors of the opposite thigh, so that the weight is taken off the paralysed extremity. When the paralysed lower extremity, say the right leg, is the active one, the line of gravity is carried over to a slight extent to that side; but instead of reaching the centre of the paralysed foot, 582 FOCAL DISEASES, ACCORDING TO it remains midway between it and the end of the stick, so that the weight of the body is maintained partly by the paralysed lower extremity and partly by the healthy arm through the stick. The healthy or left lower extremity is now quickly moved forwards a step, an unusual degree of flexion of the thigh upon the body taking place in order to avoid the necessity of carrying the line of gravity too far to the paralysed side. The left leg now becomes active, and the paralysed one must be moved forwards. The manner in which this movement is exe- cuted depends upon the degree of paralysis and of muscular rigidity present. If the paralysis be almost complete and the rigidity not great, the extremity is partly swung and partly dragged round mainly by the contraction of the inward rotators of the healthy limb. Contraction of these muscles causes the pelvis to rotate forwards on the hip-joint of the healthy side, and consequently the opposite hip-joint, dragging after it the para- lysed leg, is moved forwards. This forward movement is aided by a further elevation of the right hip-joint caused by contrac- tion of the abductors of the opposite thigh, and sometimes by a slight backward inclination of the trunk by means of which the distance between the points of origin and insertion of the flexors of the thigh on the body is increased. If a high degree of contracture with talipes equinus be pre- sent, the paralysed lower extremity is moved forwards much in the same manner as has already been described in the case of primary lateral sclerosis. When once the weight of the body is taken off the paralysed extremity the heel becomes elevated, and the toe during the forward movement, which takes place in a semicircular manner, makes a characteristic scraping noise. If tremors or choreoid movements be present in the paralysed lower extremity, the hemiplegic walk may become modified in such numerous ways as to render it impossible to comprise the different varieties which may be presented in a single description. b. Affections of the Sensory Peduncular Tract and Optic Radiations of Gratiolet. Hemianesthesia. § 742. — In cerebral hemianajsthesia the affection develops suddenly after an attack of apoplexy, or gradually as the result. i THE LOCALISATION OF THE LESION. 583 for instance, of the progressive growth of a tumour. The sensibility is diminished over the whole of one-half of the body, face, and extremities, including the accessible mucous membranes as well as the skin. The abolition of sensation is sometimes incomplete, and then cutaneous analgesia or thermo-angesthesia may be present, while tactile sensibility remains unaffected. At other times the ansesthesia of the skin and mucous membranes is complete, and even muscular sen- sibility and muscular sense are abolished. The patient, for instance, does not feel deep pressure, strong contraction of the muscles may be produced by the faradic current without causing pain, and when his eyes are closed he is unable to describe the position in which the affected extremities may be placed by passive movements, and is not aware when his attempted voluntary movements are forcibly prevented. The patient can walk without difficulty when his eyes are closed, but by slight pressure upon the affected side he may be easily induced to walk in a circle while under the impression that he is walking in a straight line. One-half of the mucous membrane of the tangue, mouth, and veil of the palate, and the conjunctiva of the same side, are insensitive, but the cornea retains its sensibility. The affected side is colder, and the prick of a pin does not bleed so readily as on the opposite half of the body. The cutaneous reflex actions may be abolished on the side affected, while the deep reflexes are retained. The senses of taste and smell are both abolished on the affected side. The sense of hearing is also diminished, and in some cases there may be complete unilateral deafness. The sense of sight is impaired but not abolished, but hemi- opia has not been observed when the lesion is limited to the internal capsule. The acuteness of vision may be tested in the usual manner by Snellen's scale. There is also concentric restriction of the field of vision, and the perception of certain colours may entirely cease (dyschromatopsia). § 743. Morbid Anatomy and Physiology. — It is impossible to separate lesions of the internal capsule and crusta from 584 FOCAL DISEASES, ACCOKDING TO those of the ganglia by which they are surrounded. Since the days of Willis and Morgagni up to a few years ago, paralysis of one-half of the body has been associated with disease of the corpus striatum. This doctrine had indeed received a shock upwards of twenty years ago, from the observations of Tiirck, who showed that hemiansesthesia of the opposite side of the body might result from disease situated in the posterior part of the lenticular nucleus. It was also suggested by Meynert and Broadbent that some of the fibres of the crusta passed upwards to reach the cortex of the brain without being in any way connected with the basal ganglia; and Charcot, with his usual readiness and skill in utilising the details of anatomical research for clinical purposes, suggested, and soon proved by observation and analysis of cases, that both hemiplegia and hemianaesthesia are caused by injury of the direct fibres which lie between the basal ganglia, and not by lesions of the ganglia themselves. We have already seen that the fibres of the posterior third of the posterior segment of the internal capsule are sensory ; that those of its middle third connect the mecha- nisms in the cortex of the brain and spinal cord which regulate the fundamental actions ; that those of the anterior third of the posterior division connect the mechanisms which regulate the specialised actions ; and that those in the knee and the anterior segment of the capsule connect the mechanisms which regulate the most specialised actions. Speaking broadly, it may be said that the fibres of the middle third of the posterior segment of the capsule are concerned in regulating the actions of the trunk, lower extremities, and probably the general actions of the upper extremities ; that the fibres of the anterior third of the posterior segment are concerned in regulating the more special move- ments of the hand as an organ of prehension, and probably also the movements of rotation of the head and neck, along with the associated ocular movements ; and that the fibres of the knee of the capsule and the adjoining part of the anterior segment of the capsule are concerned in the regulation of the movements of facial expression, articulation, and the most special movements of the hand, as those of writing. Of all the arteries of the brain the lenticulo-striate artery is, according to Charcot, the one which is most liable to rupture. THE LOCALISATION OF THE LESION. 585 This artery lies, as we have seen, between the external capsule and the external surface of the third division of the lenticular nucleus. When this vessel ruptures, if the haemorrhage be small, it may lodge between the external capsule and the lenti- cular nucleus, and give rise to no symptoms (Charcot). The vessel, however, being a comparatively large one, the hgemor- rhage, as a rule, extends beyond these limits. It is sometimes directed upwards between the external capsule and the lenti- cular nucleus, and may then extend for a considerable distance into the centrum ovale. Under these circumstances the fibres of the internal capsule become ruptured at their point of emer- gence from between the basal ganglia where they form the foot of the corona radiata. Haemorrhages in this situation may be so extensive as to extend upwards to the summits of the Fig. 242. Fig. 242 (Modified from Charcot). Vertical Section of the Brain a little behind the Knee of the Internal Capsule, showing the effects of rupture of the lenticulo- striate artery. —NG, Head, and NG', Tail of the caudate nucleus ; Gh, Chiasma ; NL, Lenticular micleus ; IK, Internal capsule ; Cls, Claustrum ; 1, The most frequent position in which the lenticulo-striate artery is ruptured ; r, 1", 1'", Progressive extension of the haemorrhage producing compression and rupture of the fibres of the pyramidal tract (hemiplegia) ; 2, Primary focus in the internal capsule ; 2', 2", 2'", Successive extension of the clot. 58(j FOCAL DISEASES, ACCORDING TO ascending frontal and parietal convolutions, while the cortex of the Island of Reil is conapressed by the clot, but the external capsule is rarely ruptured. At other times the haemorrhage is directed inwards through the grey matter of the lenticular nucleus ; and if it be large, it must impinge upon and rup- ture the fibres of the internal capsule, and when these fibres give way the haemorrhage may make its way into the lateral ventricles, then through the foramen of Monroe into the third, and through the aqueduct of Sylvius into the fourth ventricle. If the haemorrhage remain limited to the space between the external capsule and lenticular nucleus, it produces no symptoms during life; but when it makes its way into the substance of the lenticular nucleus, or into the centrum ovale above the nucleus, the fibres of the pyramidal tract are compressed, and hemiplegia of the opposite side of the body results. If the fibres of the pyramidal tract, however, remain intact, the patient will recover more or less completely from the paralysis. A case which came under my observation several years ago was that of an old man who died a few hours after being knocked down by a cab when crossing a street. The left lenticular nucleus was completely destroyed, and its usual position was occupied by a cyst containing serous fluid. No good history of the case was procurable, but he was not supposed to be suffering at the time of the injury from any form of paralysis. A still more striking case will be subsequently described, in which both lenticular nuclei were converted into cysts, the symptoms during life being those of bulbar paralysis without any evidence of paralysis of the extremities. When the haemorrhage remains limited to the lenticular nucleus, not only does the patient ulti- mately recover the full use of his limbs, but the apoplectic symptoms during the attack are slight. The patient complains of giddiness, there may be vomiting, and confusion of ideas, but he does not lose consciousness, or the loss is transitory. When, however, some or all of the fibres of the internal cap- sule rupture, the larger size of the clot produces a more pro- found immediate effect, while injury to the fibres of the pyra- midal tract gives rise to a paralysis which remains permanent. The degree and extent of the paralysis will, of course, depend upon the extent of the injury done to the motor tract. It is THE LOCALISATION OF THE LESION. 587 probable that the first form of early rigidity occurs during the time the fibres of the tract are being stretched or ruptured by the haemorrhage; the second form of early rigidity is again probably caused by irritation of these fibres, caused by inflam- matory changes in the tissues surrounding the clot ; while late rigidity is caused either directly or indirectly by descending degeneration of the ruptured fibres. But if the haemorrhage make its way either between the ascending longitudinal fibres of the corona radiata, so that a large clot forms in the centrum ovale, or if it rupture into the lateral ventricle, profound symp- toms of coma supervene, and the patient dies in a short time. We have seen that the comparatively unyielding wall formed by the external capsule directs haemorrhage from the lenticulo- striate artery inwards, and consequently the full force of the blood will impinge against the internal capsule at a point a little behind its knee, or at the point where embryological considera- FiG. 243. Fig. 243. Horizontal Section of the Basal Ganglia and Internal Capsule in an embryo of nine months.— NO, Caudate nucleus ; Tff, Optic thalamus; IIV, Island of Eeil ; //, ///, Second and third segments of the lenticular nucleus ; pc, Sensory peduncular tract ; P, Fundamental, and P', Mixed portion, and P) Geniculate fasciculus of the pyramidal tract; c, Anterior segment of the internal capsule. 588 FOCAL DISEASES, ACCORDING TO tions had led us to believe those fibres to pass, which connect with each other the nervous mechanisms in the cortex and spinal cord that regulate the movements of the hand. In hsemorrhage from this artery, therefore, the upper extremity is more paralysed than either the lower extremity or face. Eupture of the anterior branches of the artery may injure the anterior segment of the capsule to a greater extent than, the posterior segment, and then facial paralysis predominates. The fibres which conduct those impressions from the cortex which cause rotation of the head and eyes to the opposite side probably also pass in the anterior third of the posterior segment of the internal capsule, and OD the side of the capsule which adjoins the lenticular nucleus, and they also must be ruptured by a moderately-sized Fig. 244. CLs- Fig. 244 (Modified from Charcot). Vertical Section of the Brain on a level loith the Posterior Part of the Internal Capsule, showing the effects of rupture of the lenticulo-optic artery (hemianesthesia).— iVC, NC, Tail of the caudate nucleus; NL, Lenticular nucleus ; TH, Optic thalamus ; Cls, Claustruni ; 1, Primary ■ focus in the posterior part of the external capsule (hemiansesthesia) ; 1', 1", 1"', Progressive extension of the primary focus causing compression or destruction of the internal capsule ; 2, Primary focus in the internal capsule (hemianses- thesia) ; 2', 2", 2'", Successive extension of the focus. THE LOCALISATION OF TEE LESION. 589 hsemorrhage of the lenticulo-striate artery, but the conjugate deviation which results is as usual only a transitory symptom (§ 90). Hsemorrhage of the lenticulo-optic artery is also directed inwards against the fibres of the internal capsule by the un- yielding walls of the external capsule, and its greatest force impinges against the posterior half of the posterior segment of the capsule. It is evident, therefore, that hsemorrhage from this vessel will tend to injure the sensory peduncular fibres and the fibres of the fundamental mechanism, but inasmuch as the muscles of the trunk are bilaterally associated, the paralysis resulting from injury of the latter fibres will be more marked in the leg than in any other part of the body. An analysis of clinical records had led Dr. Hus^hlinors-Jackson long as^o to con- elude that the form of hemiplegia in which the leg is more profoundly affected than the arm is generally associated with hemiansesthesia. The fibres of Gratiolet are not usually affected in hsemorrhage from the opto-striate artery, and consequently the special senses are not always implicated in the ansesthesia. The anterior segment of the internal capsule is frequently injured by lesions of the head of the caudate nucleus, the resulting hemiplegia of the opposite side being thus more marked in the face than arm, and in the arm than leg, while sensibility is seldom affected. Cases are recorded of lesions of old date having been found at the autopsy without paralytic symptoms having been present during life (Nothnagel, Samt). In a case of this kind recently described by Honegger there were no descending changes ob- served in the crusta, medulla oblongata, or spinal cord, although the fibres of the middle third of the posterior segment of the internal capsule in the left hemisphere appear to have been in great part destroyed. The internal capsule may be injured by lesions of the optic thalamus. Hsemorrhage from the posterior internal optic artery, if small, does not appear to give rise to any definite symptoms, and certainly not to permanent paralysis. A large hsemorrhage from the vessel generally makes its way into the cavity of the ventricle, and death results in a short time. Lesions in the region of distribution of the posterior external optic artery are liable to implicate the fibres of the external and posterior 590 FOCAL DISEASES, ACCORDING TO extremity of the crusta and their continuations through the internal capsule. The path of least resistance to the passage of hsemorrhage from the vessel appears to be upwards and inwards ; and as the internal capsule lies below and to the outside of the thalamus, its fibres are never injured to the same extent by haemorrhages from this vessel as they are in those which take place into the lenticular nucleus. Hemi- plegia is, therefore, not a prominent feature of lesions of the optic thalamus, and when it occurs it is seldom complete. The sensory peduncular fibres, and the optic radiations of Gratiolet, are very liable to be injured by lesions in the region of dis- tribution of the posterior external optic artery, and conse- quently complete hemiansesthesia with implication of the special senses is a frequent symptom. When the lesion occurs in the pulvinar, the external geniculate body is apt to be impli- cated, and then bilateral hemianopsia of the opposite side results. When the lesion is situated more anteriorly close to the internal capsule, the fibres of the pyramidal tract suffer in- jury, and hemiplegia results. The hemiplegia is usually asso- ciated with a certain degree of hemiansesthesia, and after a time choreiform movements are apt to become established in the paralysed limbs. In six cases of post-hemiplegic chorea collected by Raymond, in which a post-mortem examination was obtained, the lesion was situated in every instance in the posterior part of the optic thalamus, and involved the fibres of the internal capsule; and in two cases of pre-hemiplegic chorea reported by him, the lesion was situated in the same locality. In a case of pre-hemiplegic chorea reported since then by Grasset, several lesions were found in different regions of the hemispheres, but one of these occupied the external margin of the optic thalamus close to the internal capsule. The lesions which have been found to give rise most frequently to hemichorea are yellow cicatrices, the remains of old haemor- rhages, or softening from occlusion of the posterior external optic artery, although choreiform movements have occasionally been observed during the growth of tumours in this region. It is evident, therefore, that the symptoms depend, not upon the nature of the lesion, but on its localisation. The symptoms do not appear to depend upon lesion of the optic thalamus THE LOCALISATION OF THE LESION. 591 itself, inasmuch as they are uever present, unless some of the fibres of the sensory-peduncular and pyramidal tracts are injured, nor does it even appear to be caused by injury of the sensory fibres, since hemiansesthesia with bilateral hemianopsia may be present without being associated with choreiform move- ments. It would seem, therefore, that injury to some of the fibres which lie in front of the sensory peduncular tract is the cause of hemichorea. That some of the fibres of the pyramidal tract are always injured in these cases can scarcely be doubted, inasmuch as the clonic are always associated with tonic spasms, and exaggeration of the tendon reflexes, the latter symptoms being those which are always associated with disease of the pyramidal tract. Two probable explanations of the clonic spasms present in these cases suggest themselves to my mind. The first is that fibres connecting the cerebrum with the cere- bellum are injured by these lesions, so that the normal propor- tion between the outgoing discharges which regulate the tonic (cerebellar) and the clonic (cerebral) actions of the body is lost. The second is that the injured fibres all belong to the pyramidal tract, and that those which suffer most are related to the more fundamental and not to the more special functions, as in disease of the lenticular nucleus. We have seen that the more funda- mental actions are regulated from the convolutions near the longitudinal fissure, while the more special movements are regulated from the convolutions bordering the Sylvian fissure ; and it is therefore manifest that the fibres which descend in the corona radiata from the former will pass along the optic thalamus side of the internal capsule, while those which descend from the latter will pass on the side of the capsule next the lenticular nucleus. The effects produced by destructive pro- cesses in any structure whatever must differ greatly according as the foundations or the latest-formed portions are the first to be injured. It appears to me, therefore, that partial injury done to the fundamental motor mechanism while the acces- sory one is left unaffected would be very likely to cause the phenomena of hemichorea. In such an event the usual tonic contractions and exaggerated tendon reflexes would result from injury of the pyramidal tract, while the apparatus ef the more voluntary and special actions, although still uninjured, would 592 FOCAL DISEASES, ACCORDING TO act in aa irregular manner owing to the damage done to the fundamental apparatus. The lesions found in cases of unilateral athetosis, although not always strictly limited to the region of the posterior external optic artery, have often been in its vicinity. In three cases of athetosis observed by Charcot the lesion was situated in the posterior extremity of the optic thalamus in one, the posterior part of the caudate nucleus in a second, and the most posterior part of the corona radiata in a third. The lesions of all these cases were situated in such positions that the same system of fibres which are implicated in post-hemiplegic chorea would be likely to suffer damage, and consequently athetosis must generally be regarded as a minor degree of post-hemiplegic chorea. In a case observed by Landouzy an old focus of soften- ing was found in the portion of the lenticular nucleus which adjoins the internal capsule. In another, observed by Gnauck, the co-existence of sensory disturbances in the region of distribu- tion of the fifth nerve on the side opposite to the spasmodic movements rendered it probable that the lesion was situated m the lateral half of the pons. It is, therefore, probable that the lesion in athetosis may occupy different positions in the vicinity of the pyramidal tract. The position occupied by the lesion in all cases rendered it probable that the fibres of the pyramidal tract are never completely ruptured, and conse- quently there are no descending changes in the cord and no muscular rigidity during life. The fibres of the tract are, how- ever, likely to have suffered partial injury by being involved in a cicatrix or other morbid change, and the impulses which pass through them become consequently irregular. Direct Cerebral Paralysis. — Although the paralysis of the extremities is usually situated on the side of the body opposite the lesion in the brain, it is occasionally situated on the same side, and is then called direct paralysis. The most reasonable supposition in these cases is that the pyramidal tracts do not decussate as usual in the medulla oblongata. The usual method of crossing is that from 91 to 97 per cent of the fibres cross over to the lateral column of the opposite side of the cord, while from 9 to 3 per cent pass downwards in the columns of Tiirck of the same side. Flechsig, however, has shown that THE LOCALISATION OF THE LESION. 593 the proportion of fibres which decussate is very variable, and he has even found that it occasionally fails altogether. It is, therefore, probable that the decussation may fail in cases of direct paralysis, although this has not yet been proved by dissection. The lesions observed in the spastic hemiplegia of childhood scarcely belong to the category at present under consideration, inasmuch as they primarily involve the cortex of the brain, while the internal capsule is only secondarily implicated. In infantile hemiplegia the lesion is situated in the convolutions of the motor area of the cortex. The primary lesion, consisting probably of a local encephalitis sometimes following an in- jury, local softening, or haemorrhage, gives rise to extensive secondary changes. In some cases a large loss of substance has been observed, causing various deformities of the skull when it occurs in early life, or leading to hydrocephalus in order to fill up the vacant space. At other times a puckered cicatrix may be found at the seat of the primary lesion, while the hemisphere has undergone a diffused consecutive atrophy. The fibres of the pyramidal tract in connection with the diseased focus undergo descending degeneration, and to it the spastic con- dition of the paralysed extremities is either directly or in- directly due. Bilateral athetosis appears also to be due to partial atrophy of the motor area of the cortex, both hemi- spheres being probably inplicated. The considerations which favour this opinion are that the affection is either congenital or becomes established in early infancy, that it is associated with some degree of imbecility or idiocy, and that there are no sen- sory disturbances. MM 594 CHAPTEE VII. (11.) SPECIAL CONSIDERATION OF FOCAL DISEASES, ACCORDING TO THE LOCALISATION OF THE LESION (Continued). 2. CORTICAL LESIONS. a. Lesions in the Area of the Middle Cerebral Artery. (i.) Monospasms and Unilateral Convulsions. § 744. Irritative lesions of the cortex are characterised by unilateral convulsions or monospasms. Lesions of various kinds may cause irritation of the cortex, the most common of these being localised meningo-encephalitis, tubercle, syphilitic gum- mata and other tumours, cicatrices of wounds and spicula of bone, and of these the syphilitic are by far the most frequent lesions. The tissues in the immediate neighbourhood of the main focus of disease are maintained in a state of irritation, and are consequently supplied by an usually large quantity of blood. The ganglion cells of the grey substance absorb an undue supply of nutriment, so that they discharge themselves in a sudden and explosive manner (Hugh lings- Jackson). But we have already seen that explosive discharges of nervous energy are followed by exhaustion and consequent paralysis of the muscles implicated in the convulsion, and accordingly unilateral convulsions are often followed by temporary paralysis of the convulsed limbs, it must be remembered that an irritative lesion is frequently associated with a destroying one. A syphilitic gumma, for instance, destroys the portion of the cortex in which it is situated, while it maintains the surrounding tissues in a state of irritation. It is not.j therefore, unusual to find a certain degree of permanent paralysis associated with unilateral convulsions. FOCAL DISEASES. 595 Unilateral convulsions were first distinguished clinically and their varieties accurately described by Bravais, although he did not recognise their pathological significance. Similar observa- tions were made by Bright and Wilks, who surmised that these convulsions were due to local disease. The pathology of these spasmodic affections was first clearly recognised by Hughlings-Jackson, and it was in explanation of these convul- sions that he first suggested the idea of the existence of motor centres in the cortex, an idea which has been so fruitful to pathology. In some cases the spasm is limited to one limb or to the side of the head (monospasm) ; in other cases it begins in one limb (protospasm), and extends to the other or to the head, to the half of the body, or the convulsions may become bilateral and generalised. Another characteristic of these convulsions is that they are either not attended by loss of consciousness or the convulsion begins before the patient becomes unconscious, so that he is afterwards able to describe a motor aura, § 745. Varieties. — The following are the clinical varieties of unilateral convulsions : — (a) Crural monospasm or protospasm, in which the spasms are either limited to the leg, or begin in it, the arm being next attacked and the face last. (b) Brachial monospasm or protospasm, in which the spasms are either limited to the arm, or begin in the arm, the face being nexb implicated and the leg last. (c) Facial monospasm or protospasm, in which the spasms are either limited to the side of the face or begin in the face, the arm being next implicated and the leg last, (a) Crural Monospasm or Protospasm. — There are not many uncom- plicated cases on record in which the spasms were limited to the leg, or invariably began in the leg, and in which a post-mortem examination was obtained. Ferrier quotes a case recorded by Broca of crural monospasm caused by injury to the left side of the skull, which was cured by trephining, but the exact position on the brain is not mentioned. Charcot and Pitres quote a case from Griesinger of frequently recurring spasm of the leg and arm. Numerous cysticerci were found in the brain, the largest of which occupied the superior part of the ascending parietal convolution of the opposite side. Several small cysts were found on the frontal and parietal surface of the same hemisphere, Hughlings-Jackson reports a case in which the fits were often limited to the leg, and always began there. The leg became gradually weaker after each attack, and 596 FOCAL DISEASES, ACCORDING TO finally became permanently paralysed. A tumour was found at the upper and posterior part of the left frontal lobe, about two inches in diameter, ex- tending from the posterior extremities of the first and second frontal con- volutions backwards to the fissure of Rolando. In another case recorded by the same author, the convulsions began in the left great toe, and were often limited to the left leg. A syphilitic lesion was found at the upper part of the ascending parietal convolution and over several of the adjacent convolutions of the parietal lobule. Bourneville describes a case of th.e hemiplegia of infancy, in which the convulsions began by tremors and twitching in the left or paralysed leg. The cortex of the right hemisphere Fig. 245. was found atrophied in front of the fissure of Rolando in the superior half of the ascending frontal, the posterior extremities of the first and second frontal {Fig. 245), and the whole extent of the paracentral lobule. {h) Brachial Monospasm or Protospasm, — Several cases are recorded in which the spasm is either limited to or begins in the arm. Instances of this kind have been recorded by Dr. Hughlings- Jackson. In the case of one man who suff"ered from repeated convulsions limited to the right arm with subsequent paralysis, a nodule was found situated at the posterior extremity of the first frontal convolution of the left hemisphere. In another case, in which the spasms were almost similar to those observed in the last case, a nodule was found situated at the posterior extremity of the first frontal convolution where it joins the ascending frontal. The spasm in this case began in the shoulder and went down the arm, con- trary, Dr. Jackson thinks, to the usual order. In a third case the spasm invariably began in the left thumb, and a tumour of the size of a hazel-nut was found under the grey matter at the posterior extremity of the third frontal convolution of the right hemisphere. In a fourth case the spasms began in the right arm, and occasionally in the right side of the face, and the patient had suffered from a transitory attack of left hemiplegia. In the left hemisphere adhesion was found between the dura mater and the brain, over " the lower part of the ascending frontal and ascending parietal con- volutions, to a trifling extent to the hinder part of the third frontal and THE LOCALISATION OF THE LESION. 597 several of the convolutions of the upper wall of the fissure of Sylvius behind the ascending parietal." In the right hemisphere, the side opposite the paralysis, a mass was found behind the fissure of Rolando, but has no bearing upon our present subject. In a fifth case temporary right hemiplegia supervened after a unilateral convulsion. Convulsions recurred repeatedly, beginning in the little finger of the right hand, occasionally in the right side of the face, and always followed by slow and hesitating speech. A syphilitic tumour of considerable size was found in the cortex about the junction of the frontal and parietal lobes, surrounded by an area of softening in the posterior extremities of the frontal, ascending frontal and ascending parietal convolutions, and partly of the Island of Reil. A case of partial epilepsy is reported by Ballet and Lalesque in which the spasms began in the right hand. Paresis of the right arm supervened, the right side of the face and tongue being also implicated to a slight degree as the case progressed. Some degree of embarrassment of speech was also present before death. At the autopsy three small hydatid cysts were found in the cortex of the left hemisphere, one being situated about the middle of the ascending frontal convolution, the second at the junction of the middle and lower thirds of the ascending parietal convolution, and the third at the posterior extremity of the second frontal convolution. A case of brachial protospasm, caused by syphilitic disease, has been recorded by Dr. Dreschfeld, in which I conducted the post-mortem exami- nation, confirming the diagnosis made by Dr. Dreschfeld during life. The attacks began "by sudden clenching of the fist, flexing of the wrist, and Fig. 246. pronation of the forearm of the left side, the corresponding angle of the mouth being at the same time drawn downwards. This sudden tonic spasm lasted for several seconds, and was then followed by a few clonic spasms of the same extremity and a slight tremor of the arm, the patient being at the same time agitated and pale, but perfectly conscious." The dura mater was found adherent to the brain on the right side over the greater part of the ascending parietal convolution and the supra-marginal lobule {Fig. 246). 598 FOCAL DISEASES, ACCORDING TO The case of a boy, three months old, is reported by Mr. Cullingworth, who developed cerebral symptoms somewhat suddenly nearly four months sub- sequently to an injury to his head. The symptoms began by screaming and elevation of temperature. A few hours later it was observed that the left arm and hand were flexed and rigid, and this was soon followed by conjugate deviation of the eyes to the right. The dura mater was found thickened and adherent to the bone over a small area of the right hemi- sphere immediately to the right of the longitudinal fissure. The cortex underlying the adhesions was reddened and softened, the softened part involving the upper portion of the ascending frontal convolution. A layer of pus was found over the whole surface of both hemispheres and the greater portion of the cerebellum. Charcot and Lepine describe a case of partial epilepsy beginning in the left arm in which after death a hsemorrhagic focus was found situated in the posterior part of the first right frontal convolution. In another case of partial epilepsy beginning in the left arm, described by the same authors, an old focus of softening was found between the first and second frontal convolutions of the right hemisphere where they adjoin the ascending frontal convolution ; while in another case described by them, the convulsions began in the right arm, and a small focus of disease was found in the superior part of the ascending parietal convolution of the left hemisphere. A case is described by Glicky, in which the convulsions began in the left arm, but subsequently involved the left half of the body ; a glioma was found which had destroyed the two ascending central convo- lutions and the paracentral lobule on the right side. Mahot reports a case of partial convulsions beginning in the fingers of the left hand, in which a tuberculous mass was observed imbedded in the substance of the right ascending frontal convolution in its middle third. Berger reports the case of a woman who suffered from convulsions of the right arm with subse- quent weakness of the same, the convulsions after a time became general, and the right arm was completely paralysed, while there was weakness of the muscles of the leg and face. A sarcoma growing from the dura mater had penetrated into the cortex of the brain over the left ascending frontal convolution, opposite the posterior extremity of the second frontal convolution. Burresi describes a case of partial epilepsy of the left arm followed by paresis, and at last by complete paralysis ; a tuberculous mass was found in the fissure of Rolando. (c) Facial MonosjMsm or Protospasm. — The case of a French soldier is described by Hitzig, who, two months after a bullet wound on the right side of the head, suffered from clonic spasms followed by paralysis of the left side of the face and tongue. An abscess was found in the cortex of the right hemisphere situated in the inferior part of the ascending frontal on a level with the third frontal convolution. Wernher reports a case in which there were convulsions of the muscles of the face, neck, forearm, and of the extensors and flexors of the fingers, all on the right side. The lesion was situated in the cortex of the left THE LOCALISATION OF THE LESION. 599 hemisphere iu the inferior part of the ascending frontal convolution near the fissure of Sylvius. The case of a woman is described by Dr. Bramwell, who, after a cranial injury received some years previously, began to have right-sided convul- sions. The convulsions always began in the right platysma, and were often almost entirely confined to this muscle. A spiculum of bone was found projecting from the inner table of the skull, and causing a limited lesion of the inferior margin of the ascending parietal convolution {Fig. 247). Fig. 247. Seeligmuller describes a case of epileptiform convulsions of the right half of the face, followed after a^time by facial paralysis. At a some- what later period the right arm became convulsed, and afterwards paralysed. A sarcomatous tumour was found in the ascending parietal convolution, which probably began to grow at its lower extremity and progressed upwards. These cases tend to show that convulsions, either limited to or begin- ning in the face, are caused by a lesion situated in the inferior part of the ascending frontal and parietal convolutions, the portion which adjoins the fissure of Sylvius. (ii.) Cortical Paralyses and Monoplegia. § 746. It is now well established that destructive lesions of the cortex of the brain cause permanent paralyses. Destroying lesions of the motor area of the cortex may be divided into (1) General lesions, extending over the greater part of the area ; and (2) Partial or localised lesions, limited to small portions of it (Ferrier). (1) General or Extensive Lesions (Hemiplegia). — Extensive 600 FOCAL DISEASES, ACCORDING TO lesions of the cortex give rise to complete hemiplegia, similar in all essential particulars to that resulting from disease of the internal capsule. A case of complete hemiplegia of the right side of six years' duration is described by Lupine in which there was total destruction, caused by yellow softening, of the ascending parietal convolution and partial de- struction of the Island of Reil, ascending frontal convolution, and of the anterior part of the superior and inferior parietal lobules of the left Fig. 248. hemisphere {Fig. 248). Secondary degeneration was traced in the left half of the pons and in the left pyramid of the medulla. Duret reports a case of complete right hemiplegia supervening in the course of a meningo- encephalitis. A thick fibro-purulent exudation occupied the three frontal convolutions of both sides, but it extended on the left over the ascending frontal and ascending parietal convolutions, the lobule of the pli courbe, and the parietal lobule. A case of right hemiplegia with aphasia of one year's duration, accom- panied by late rigidity of the paralysed limbs, is reported by Charcot and Pitres, in which a patch of yellow softening was found, involving the whole of the ascending frontal, the base of the third frontal, and the whole of the ascending parietal convolutions, along with the inferior parietal lobule and the two posterior digitations of the Island of Reil in the left hemisphere. The basal ganglia were normal. Secondary degeneration was observed in the crus, pons, and anterior pyramid on the same side. A case is quoted by Trousseau which occurred in the dinique of Charcot, in which left hemiplegia existed for three months ; the ascending frontal and third frontal convolutions, and Island of Reil in the right hemisphere were found softened. Secondary degeneration was traced in the crus, pons, and pyramid of the same side as the lesion, and on the THE LOCALISATION OF THE LKSION. 601 opposite side of the spinal cord {Fig. 249). Cases of this kind naight be multiplied, but it would occupy too much space to narrate them. The following cases are examples of hemiplegia, caused by lesions of the cen- trum ovale. Fig. 249. A case of right hemiplegia, with late rigidity of the paralysed limbs, is related by Hodgson, in which a cavity of considerable size was found in the centrum ovale of the left hemisphere, situated between the anterior horn of the lateral ventricle and the Island of Reil. The rest of the brain was normal. Dussaussay describes a case, quoted by Pitres, of right hemiplegia Tig. 250, with conjugate deviation of the eyes to the left. A cavity was discovered in the centrum ovale of the left hemisphere, containing dark, coagulated blood {Fig. 250). The cavity was limited internally by the grey substance 602 FOCAL DISEASES, ACCORDING TO of the paracentral lobule, superiorly and externally by the grey substance of the ascending frontal and parietal convolutions ; in front it extended to the pra3-central fissure, and behind to the posterior border of the ascend- ing parietal convolution ; while it was separated inferiorly from the corpus striatum by a layer of white substance Ice. in thickness. Dr. Ringrose Atkins has recorded a case of right hemiplegia due to embolism, in which, in addition to a patch of softening at the lower extremity of the ascending parietal convolution {Fig. 251), there was a Tig. 251. focus of softening two inches in diameter in the centrum ovale, extending from a point '2\ inches behind the apex of the left frontal lobe to a point 3|- inches outward to the apex of the occipital lobe. The basal ganglia were normal. (2) Partial or Localised Lesions of the Motor Area of the Cortex — Monoplegioe. (a) Crural Monoplegia. — The recorded cases of disease of the cortex in which the paralysis was limited to the leg are not numerous. A sufficient number are reported to render the existence of a cortical centre for the regulation of the movements of the lower extremity more than probable, even from clinical evidence alone and in the absence of the more elaborate proof afforded by experiment on animals. Loffier describes the case of a Danish corporal, who was struck by a bullet at the superior and posterior extremity of the left parietal bone, close to the sagittal suture. The right leg was immediately paralysed, and the right arm on the seventh day after the accident. On trephining, recovery took place, the arm being first restored and then the leg. In another case reported by the same author, fracture of the summit of the right parietal bone was followed by paralysis of the left leg. The case of a woman, aged 76 years, is reported by Oudin, in which there was paralysis with contractures and arrest of development of the THE LOCALISATION OF THE LESION. 603 right lower extremities, dating from the age of nine and a half years, and following a fall. At the autopsy the median parts of the superior surface of the hemispheres were found to present a remarkable asymmetry. The posterior extremity of the first frontal and superior extremity of the ascending frontal convolution were remarkably atrophied ou the left hemisphere, while the corresponding parts of the right hemisphere were normal and of comparatively large size. The superior portions of the ascending parietal convolutions were atrophied on both sides, although the atrophy in the left hemisphere was more pronounced than in the right. The anterior extremity of the superior parietal lobule was also involved in the atrophy on the left side {Fig. 252). Fig. 252. Dr. Haddon, of Manchester, records a case in which paralysis remained limited to the left leg for five months, but after a time the left arm also became paralysed. After death a tumour three inches in diameter was found connected with the dura mater, situated to the right of the middle line, compressing the subjacent hemisphere, and destroying the upper ex- tremities of the ascending frontal and parietal convolutions, as well as the postero-parietal and paracentral lobules {Figs. 253 and 254). The case of a man, set. 40 years, is reported by Dr. Ferrier, in which the symptoms of general tuberculosis were complicated by monoplegia of the left lower extremity. The paralysis was strictly limited for four days to the left leg, but subsequently extended to the left arm. The patient died a month subsequently to the appearance of the paralytic symptoms, and at the 604 FOCAL DISEASES, ACCORDING TO autopsy the pia mater over the upper margin and internal aspect of the right hemisphere on both sides of the fissure of Rolando was merged into a caseous mass, which could not be removed without tearing the cortical substance. The lesion occupied the quadrilateral lobule on the internal Fig. 253. aspect of the hemisphere, and the upper extremities of the ascending parietal and frontal convolutions on its superior and external aspect, the portion of the cortex implicated corresponding to the areas marked 1 and 2 on the monkey's brain {Figs. 230 and 231). Fig. 254. THE LOCALISATION OF THE LESION. 605 (b) Brachio-crural Monoplegia. — Paralysis of the leg and arm are frequently associated in disease of the cortex. Charcot and Pitres de- scribe a case of paralysis with rigidity of the limbs of three years' duration, in which a patch of softening was found at the upper extremity of the fissure of Rolando on the convex surface of the right hemisphere Fig. 255. {Fig. 255). Hughlings- Jackson reports a case of paralysis of the left ex- tremities caused by a glioma situated in the superior part of the fissure of Rolando, and comprising the ascending parietal convolution and the Fig. 256. parietal lobule. A larger number of examples of brachio-crural monoplegia resulting from cortical disease might be quoted, but these must suffice. Pitres describes a case of paralysis with unilateral convulsions of the 606 FOCAL DISEASES, ACCORDING TO left extremities in which a focus of softening was found, not in the cortex, but in the centrum ovale, immediately beneath the posterior extremity of the first frontal convolution {Fig. 256, L), and extending backwards underneath the superior parietal lobule. (c) Brachial Monoplegia. — A case of paralysis of the left arm is de- scribed by Pierret in which a centre of softening was found in the cortex of the right hemisphere at the point where the second frontal joins the Fig. 257. ascending frontal convolution {Fig. 257). Boyer records a case in which the arm and leg became suddenly paralysed, the paralysis of the arm alone remaining permanent. Death took place five years subsequently to this attack, and a patch of atrophy was found on the right hemisphere in the ascending frontal and parietal convolutions, with an extension of the lesion to the temporo-sphenoidal lobe. A case of paralysis of the right hand and arm is reported by Ringrose Atkins supervening a few days before death in a patient suffering from general paralysis. The cortex was softened in the middle of the ascending frontal and parietal convolutions, the lesion also extending backwards along the anterior edge of the supra-marginal gyrus as shown in Fig. 258. Fig. 258. THE LOCALISATION OF THE LESION. 607 Decaisne has collected a large number of cases of brachial monoplegiae, but it would occupy too much space to quote more cases at present. It may be observed in passing that the central convolutions of the oppo- site hemisphere have been found atrophied in cases of long-standing amputation (Chuquet, Boyer). The results obtained have not, however, been very definite. Dr. Gowers found in a case of congenital absence of the left hand the middle part of the ascending parietal convolutions in the right hemisphere distinctly smaller than the corresponding convolutions in the left, and a somewhat similar case has been recorded by Bastian. (d) Brachio-facial Monoplegia. — Paralysis of the face and arm are not uncommonly associated. When the left hemisphere is the seat of the lesion, these cases are usually associated with aphasia. Dieulafoy records a case of paralysis of the face and arm in which the autopsy revealed a hsemorrhagic focus, the size of a nut, situated in the ascending frontal con- volution on a line with the third frontal convolution. Troisier mentions a case of paralysis of the arm and face in which tubercular granulations and congestion were found immediately posterior to the third frontal convolu- tion. Landouzy describes a case of slight paralysis of the inferior facial muscles and of the arm caused by a spot of tubercular meningitis occupying the inferior part of the fissure of Rolando, and the inferior half of the two ascending convolutions. Pitres quotes from Anton Frey a case in which there was paresis of the left arm and of the left side of the face; the autopsy showed a focus of softening in the medullary fibres at the junction of the middle frontal with the ascending frontal convolutions {Fig. 259). (e) Facial Monoplegia. — Facial paralysis of cerebral origin is generally complicated by aphasia or paralysis of the arm, but a few uncomplicated cases of facial paralysis from diseases of the cortex have been observed. Tig 259. Fig. 260. G08 FOCAL DISEASES, ACCORDING TO Charcot and Pifcres describe a case of apoplexy followed by left hemi- plegia and rigidity of the limbs. The rigidity disappeared after a time and the paralysis became limited to the lower facial muscles. An extensive area of softening was found in the cortex of the right hemisphere, invading the third frontal, the lower extremities of the ascending frontal and parietal convolutions, and a large extent of the parietal and temporo- sphenoidal lobes of the Island of Keil {Fig. 260). Although the cortical lesion in this case was so extensive, it will be seen that disease of the inferior extremities of the ascending convolutions was the important lesion so far as the motor area is concerned. Hitzig relates the case of a soldier who received a bullet-wound on the right side of the head and became affected two months subsequently with clonic spasms in the left side of the face, followed by paralysis of those muscles and of the left half of the tongue. After death an abscess was found in the ascending frontal convolution between the prse-central fissure and the fissure of Rolando, corresponding to the seat of injury {Fig. 261). Fig. 261. A case of left hemiplegia is reported by Dr. Gowers in which gradual recovery took place, with the exception of marked paralysis of the inferior facial muscles. At the autopsy a hsemorrhagic extravasation was found in and beneath the upper half of the prse-central sulcus which had passed into the substance of the adjoining convolutions, consisting of the posterior extremities of the middle and superior frontal and corresponding part of the ascending frontal of the right hemisphere. A large number of cases might be cited in which right facial paralysis existed, associated with aphasia, and in which the lesion was situated at the junction of the third frontal with the ascending frontal convolution of the left hemisphere. The case of a woman, aged 71 years, is reported by Ballet, who had a slight attack of apoplexy without loss of consciousness. The permanent symptoms consisted of paralysis of the left half of the face and of the tongue. There was also slight feebleness of the left upper extremities, but the lower was unaffected. There were no sensory disturbances. Towards the evening of THE LOCALISATION OF THE LESION. 609 the same day the head and neck became deviated to the right and the paralysis of the left arm became more marked. Death took place from coma four days subsequently to the beginning of the attack, and at the autopsy a hsemorrhagic focus, of the size of a large nut, was found in the inferior part of the ascending frontal convolution {Fig. 262). The in- ferior frontal and inferior parietal fasciculi of the white tissue were partially destroyed, but the basal ganglia were normaL Fig. 262. (/) Unilateral Oculo-motor Monoplegia. — It has already been mentioned that conjugate deviation of the eyes and rotation of the head and neck are frequent symptoms both of convulsions and of hemiplegia, and that the deviation in the former is directed away from, and in the latter towards the hemisphere in which the lesion is situated. In the brain of the monkey, Ferrier localises a centre {Fig. 232, 12) in the posterior extremity of the second frontal extremity, irritation of which causes elevation of the eyelids, dilatation of the pupils, conjugate deviation of the eyes, and turning of the head to the opposite side ; while, on the other hand, extensive movements of the eyeballs, along with associated movements of the head and neck, result from irritation of the supra-marginal and angular gyri (Fig. 232, 13, 13'). A case is reported by Chouppe which appears to show that the centre for the production of conjugate deviation of the eyes and rotation of the head and neck is situated in the posterior extremity of the second frontal convolution. The case as quoted by Landouzy was that of a young man, 19 years of age, who presented the ordinary symptoms of tubercular meningitis, the most striking being a rotation of the head and eyes to the right without any other paralysis. After death a superficial focus of disease, of the size of a franc piece, was found on the posterior extremity of the middle frontal convolution in the left hemisphere. Other lesions were found in the superior and lateral part of the sphenoidal lobe of the right hemisphere. Landouzy thinks that the deviation of the eyes was caused by an irritative lesion of the posterior extremity of the second frontal convolution, but it must be remembered that the lesion in the N N 610 FOCAL DISEASES, ACCORDING TO superior part of the sphenoidal lobe was close to the angular gyrus, and it is probable that the deviation was due to a destroying lesion in this area. The case of a child, aged five months, is mentioned by Farrier, on the authority of Dr. Carroll, of New York, in which a fracture of the skull was produced by a fall. When Dr. Carroll saw the patient, the head was rotated to the right, its range of motion never extending to the left of the middle line ; the eyes, when at rest, were turned to the right, but could be voluntarily moved almost to the middle line ; pupils, perhaps, a little dilated, but responsive to light ; upper lids elevated. There was a fracture in the right parietal region, and a linear fracture could be detected in the parietal bone, about midway between the squamous and sagittal sutures, and intersecting a vertical line drawn upwards from the auditory meatus. The position of the fracture was, as pointed out by Ferrier, such as might coincide with injury of the posterior extremity of the second frontal con- volution, the lesion being doubtless of a paralytic nature. It must, how- ever, be admitted that these two cases are not of themselves sufficient to prove the existence of a centre for the rotation of the eyes situated in the middle frontal convolution. Strong evidence has indeed been recently brought forward by Grasset to show that when conjugate deviation of the eyes is caused by disease of the cortex, the lesion is situated in the supra-marginal and angular gyri. He reports a case of left hemiplegia with conjugate deviation directed to the right, in which the lesion consisted of disease of the pli courbe of the right hemisphere {Fig. 263). Liouville describes a case of right unilateral Fig. 263. convulsions in which the head was strongly turned towards the right. The lesion, which consisted of tubercular meningitis, was situated on both sides of the horizontal limb of the fissure of Sylvius on the left hemisphere. Sergiu reports a case of left hemiplegia with contracture of the muscles of the right side (probably paralysis of the muscles of the left side) of the neck. The lesion consisted of a meningo-encephalitis in the right middle THE LOCALISATION OF THE LESION. 611 lobe at the level of the superior part of the fissure of Sylvius. Charcot and Pitres mention a case reported by Samt, in which there was right hemiplegia, while the head and eyes were deviated to the left. A focus of softening was found situated upon the parietal lobe, not quite reaching the ascending frontal convolution in front, bounded posteriorly and in- feriorly by the posterior extremity of the parallel fissure, and passing beyond the interparietal fissure superiorly, but not quite reaching to the great longitudinal fissure. These cases, although many more might be added, will sufl&ce to show the importance, with regard to conjugate deviation of the eyes, of the convolutions which border the posterior extremities of the Sylvian and parallel fissures. Many cases are recorded in which conjugate deviation of the eyes was caused by disease of the centrum ovale, and in these the lesion was, as a rule, situated between the internal capsule and the supra-marginal and angular gyri. Provost reports a case of right hemiplegia with rotation of the head and eyes to the left. A haemorrhagic focus was found in the posterior part of the parietal lobe of the left hemisphere. In another case reported by the same author right hemiplegia, with rotation of the head and eyes to the left, was caused by a sarcoma, of the size of a pigeon's egg, situated in the centrum ovale behind the fissure of Rolando, and along the longitudinal fissure. It would appear that disease in the neighbourhood of the angular gyrus and supra-marginal lobule produces at times paralysis of the levator pal- pebrae superioris of the opposite side, without the other muscles supplied by the third nerve being implicated (Landouzy). Lesions may occur in the cortex of the brain in the area of distribution of the middle cerebral artery without being attended by paralysis. Boyer maintains that there are two " neutral " zones in the area, the one occu- pying the superior parietal lobule, and the other the anterior part of the praecuneus and a part of the gyrus fornicatus, A case is reported by Dr. Ringrose Atkins, in which there was a superficial erosion of the cortex on the postero-parietal lobule of the left hemisphere without motor disturb- ance having been present during life. I would suggest that the neutral zones of Boyer are associated with centrifugal fibres connecting the cortex of the brain with the cerebellum. Other cases are recorded in which the cortical motor centre of the leg was found diseased at the autopsy, yet in which the leg on the opposite side either had never been paralysed or had recovered. It is probable that in such cases the movements of both lower extremities were regulated from one hemisphere, the one on the side opposite the lesion receiving its impulses through commissural fibres in the spinal cord. The motor area of the cortex may be compressed by very large tumours without paralysis being produced. In the Pathological Museum of the Owens College there is a preparation, presented by Mr. Windsor in 1877, of a sarcomatous tumour, about the size of the closed fist, which grew from the dura mater over the vertex, and near to the falx cerebri. The 612 FOCAL DISEASES, ACCORDING TO underlying hemisphere was compressed and flattened, the motor area of the cortex being involved, but the patient had no paralytic symptoms during life. Two cases of a more or less similar kind have been recently described by Pitres. Sensory Disturbances. — It has been maintained by Tripier that lesions of the cortical motor area of the brain are sometimes attended by hemiansesthesaa as well as paralysis of the opposite side of the body, tactile sensibility being specially affected. He adduces in favour of this opinion some experimental evidence, and reports of seven clinical cases in which more or less of hemiplegia was associated with hemianaesthesia, the lesion in all of them being found limited to the motor area of the cortex of the hemisphere opposite to the side affected. But hemi- ansesthesia so frequently results from functional disturbances of the brain that it would be somewhat hazardous to conclude from these cases alone that the lesion of the motor area of the cortex was the cause of the loss of sensibility. Several cases are collected by Nothnagel to show that diminution of the muscular sense is not unfrequently associated with motor paralysis from cortical disease. He thinks that the cortical centres of the muscular sense lie near to, although they are not identical with, the motor centres. Vaso-motor and trophic disturbances, consisting of elevation of the temperature of the paralysed limbs and acute bed-sore, have been observed in cases of disease of the cortex of the brain, but they do not possess any value as localising symptoms. (iii.) Affections of Speech feom Coeiical Disease. § 747. The disorders of speech which are liable to occur in cortical disease constitute one of the most complicated problems of neurology; and before proceeding further, it is desirable to limit our subject so as to separate disorders of speech due to disease of the cortex of the brain from other affections of the nervous system that may resemble them. Language, taken in its widest sense, consists of the various means by which animals indicate mental states to one another. Mental states may be, as we have seen, divided into feelings, cognitions, and volitions. In one sense language may be said very often, if not always, to indicate volitions ; but inasmuch as volitions are practically always determined by what are called motives, or in other words by the feelings and cognitions, the language of volitions merges itself into that of the other two mental states. Language may therefore be divided into that of the feelings or emotional language, and that of the cognitions or intellectual language or speech. THE LOCALISATION OF THE LESION. 613 But the division between the language of the emotions and speech is by no means clear and trenchant. When a man delivers an oration, for instance, only a small part of what he utters is speech. All the variations of tone, the melodious voice, the graces of attitude and gesture, the charm of elegant and rhythmical language, and the thousand other ways by which a great orator knows how to sway and influence his audience, belong to emotional and not to intellectual language. Similar remarks apply to written language. The pleasure we derive from looking at a clearly-printed volume, and especially from looking at an illuminated text, the pleasure derived from looking at a well-executed picture rather than at a diagram, the methods, as accent, italics, and notes of exclamation, by which inflection and emphasis and wonder are indicated; the rhythm of metrical language, and the diction and imagery of poetry belong to emotional language. The languages of emotional and of intellectual gesture are also by no means readily separated. The gestures of those who retain the full use of spoken and written language are in great part indicative of the feelings, but that gesture can be made subservient to intel- lectual expression is shown by the importance it assumes in the intellectual training of the deaf and dumb. Language is the instrument of the social state, and that it may be the means of intercommunication between animals it possesses to each a subjective and an objective value, or fulfils an impressive and expressive function. Each individual of a social community, in order to become an effective member, must be able to feel or comprehend the mental states of the others from watching their gestures and listening to their various vocalisations, and must also be able by his gestures and vocalisa- tions to render his own mental states intelligible to the others. The subjective or impressive function of language, or rather of speech, with which we are here more immediately concerned, may be subdivided into receptive and regulative functions. The receptive department is represented structurally by the various peripheral sense-organs and the centripetal fibres, or cells and fibres, which conduct impressions made upon the former to the cortex. Complete loss of speech from disease of the receptive apparatus is unknown. 614! FOCAL DISEASES, ACCORDING TO The vocal speech of a person born blind is almost entirely unaffected either in its subjective or objective aspects, while the patient may, by the device of raised letters, be taught to understand written language. The deaf mute is taught both to understand and to give expression to a complicated speech by gesture ; and in recent times such patients have been taught to use their vocal organs for expression in speech, while they are made to understand the vocal speech of others by closely ob- serving the movements of the muscles of articulation. The remarkable case of Laura Bridgeman, who became blind and deaf in her second year, while her sense of smell and taste were also very deficient, shows how much careful training may do in developing language and thought through the sense of touch. This girl was taught by Dr. Howe, of Boston, who affixed on a number of common objects labels on which the name of the article was written in raised characters. After she had learnt to associate each label with its object, a number of separate labels were put in her hand, and she was then encouraged to place each label on its corresponding object. After a time the separate letters were placed in her hand, and she was then taught to put them together so as to form the names of common objects. " Up to this," says Dr. Howe, " the proceeding was only a mechanical one, and the result was about as great as if one had taught a number of tricks to a clever dog. The poor child had sat there in mute astonishment, and patiently imitated everything that was performed before her. But now the matter seemed to dawn upon her in its true light, her understanding began to esercise itself, she noticed that she now possessed the means of arranging for herself symbols of some- thing that lay before her mind, and of showing this to another mind ; immediately her countenance beamed with human reason ; she could no longer be compared to a parrot or dog ; the immortal intellect now seized greedily upon this new bond of union with other intellects ! I could almost point out the moment at which this truth dawned upon her and poured light over her whole face," The structural counterpart of the regulative function consists of that part of the cortex of the brain in which the centripetal impulses are reduced to such order as is necessary to render them the correlatives of the cognitions. Now, the cognitions, as we have seen, express the relations between our feelings, and all cognitions must be expressed by propositions. The mode of expression may not always assume a distinct propositional form, but it must at least possess a propositional value if it convey distinct knowledge. If I repeat the word " orange " in the hearing of another, it may, or may not, convey to him distinct THE LOCALISATION OF THE LESION. 615 information ; but if any information be imparted, the word must convey to the listener the idea that the object named "orange" belongs to a class of objects already known to him under that name, and the word in this sense possesses the value of a distinct proposition. If the listener has never had any experience of the object named "orange," it is clear that the utterance of the name will convey no meaning ; but if he has had experience of other fruits and of colours, distinct information may be conveyed to him with regard to the object by saying " an orange is a yellow fruit." The listener will be able to associate the general properties of fruit and a distinct colour with the word in future, but the information has been im- parted by means of a formal proposition. The activity of the regulative cortical centres of speech have for their functional correlative the arrangement of the presentative and represen- tative cognitions into the form of distinct mental propositions. The objective or expressive function of speech may be sub- divided into emissive and executive departments. The emissive department is represented structurally by that organisation in the cortex of the brain in which the regulative impulses are finally co-ordinated before being conducted to the executive department. The executive department is represented structurally by groups of nerve cells in the central grey tube, and by the nerves and muscles concerned in vocalisation, articulation, the manual operations of writing, and various gestures. Com- plete loss of speech from disease in the executive structure is most unusual. The patient, for instance, may lose his voice in different diseases of the larynx, but he can still arti- culate; he may lose both voice and articulation in bulbar paralysis, but is generally able to make known his wants in writing, and • when unable to write from want of previous education he can make his ordinary wants known by gesture. Our further remarks must be limited to the derangements of speech caused by disease of the cortex of the brain. These consist of disorders of the regulative department of the im- pressive function, and of the emissive department of the expressive function; and as the latter is probably the simpler of the two, we shall deal with it first. 616 FOCAL DISEASES, ACCORDING TO § 748. (