TEE CEREBRUM. 



Fig. 328 





with the crura cerebelli, and on the other terminate in the cells of the grey- 

 substance. 



In the grey spot that forms the corpus rhomboideum, is a great number of 

 large nerve-cells. 



With regard to structure, the grey matter of the cere- 

 bellum may be decomposed into two layers ; the super- 

 ficial is very rich in blood-vessels, has a greyish tint, and 

 is composed of large nerve-cells and smaller rounded ele- 

 ments ; the deep layer is of a yellow colour, and also 

 contains nerve-cells and round elements, though the latter 

 are smaller than in the other layer, and have been sometimes 

 mistaken for simple nuclei. 



DIFFERENTIAL CHARACTERS OF THE CEREBELLUM IN OTHER THAN 

 SOLIPED ANIMALS. 



The external and internal conformation of the cerebellum offers 

 the closest analogies in the domesticated mammifers. In all, its 

 volume, compared with that of the other encephalic lobes, is not 

 invariable. Thus, while the relation between the weight of the cere- 

 bellum and that of the brain of the Horse is as 1 to 7 ; with the Ox 

 it is as 1 to 9 ; with the Dog 1 to 8 ; with the Cat 1 to 6 ; and with 

 the Sheep 1 to 3. These are the only differences to be noted 



COMPARISON OF THE CEREBELLUM OF MAN WITH THAT OF ANIMALS. 



In Man, the encephalic mass being enormous, the cerebellum 

 is absolutely more considerable in volume than in the larger domesti- 

 cated animals ; though, in proportion to the cerebral hemispheres, it 

 is smaller than in the Ox, its relation to the latter lobes being us 

 1 to 8. i^H 



It is wider than it is long, and projects much beyond the medulla 

 oblongata. It has three lobes; but these are only visible on its 

 lower aspect ; on the opposite face, the median lobe is depressed and iwmv 



concealed beneatli the lateral lobes, which are so large that they SECT1ON OF 

 have been named the cerebellar hemispheres. The inferior veimis 

 forms a free projection in which is the fourth ventricle; this is 

 termed the uvula of the cerebellum. The uvula is connected at each 

 side with the valves of Tarin : laminse of nerve-substance lodged for 

 the most part in the fourth ventricle, and hidden by the lower face a ' Meduhal T sub ~ 

 of the cerebellar hemispheres. The latter constitute, on the sides of stance, showing 

 the medulla oblongata, two prominences situated one below the other, ibres; 6, Su 



above the crura cerebelli; the first is designated the amvqdala or stantia ierrugi- 



nea, composed of 



TH1C 



CORTICAL SUB- 

 STANCE OF THE 

 CEREBELLUM. 



the second the pneumogastric lobule (o? flocculus}. 



fibres and cell- 

 nuclei ; c, Grey 

 surface, granu- 

 lar at the sur- 

 face, and contain- 

 ing large mul- 

 tipolar branch- 

 ing cells near 

 the substantia 

 ferruginea. 



ARTICLE IV. THE CEREBRUM. 



The cerebrum, the principal portion of the encephalon, 

 comprises the two anterior lobes or hemispheres of that 

 apparatus : enlargements which are elongated in the direc- 

 tion of the great diameter of the head and cranial cavity, 

 lie beside each other on the middle line, and are united 

 at their central part by a transverse commissure, and by 

 the encephalic isthmus, whose anterior extremity penetrates, inferiorly, 

 into their substance. (See Fig. 329 for a good idea of this penetra- 

 tion.) 



These two lobes together represent an ovoid mass, having its thick 

 extremity adjacent to the cerebellum ; it is depressed from above to below, 

 deeply divided above, in front, and behind by a median antero-posterior 



