518 



CEREBELLUM. 



successively the inferior posterior lobe, the slender lobe, the liventral lobe, 

 the amygdala (fig. 361, 4), and the subpeduncular lohe or flocculus. This 

 last-named lobule projects behind and below tlie middle peduncle of 

 the cerebellum. It is connected by a slender pedicle of white fibres to 

 tlie rest of the hemisphere ; but its exposed surface is grey, and is sub- 

 divided into five or six small laminre. 



Vallecula. — Within the vallecula (fig. 3G2), or on its borders, the 

 following parts are seen. 



Commencing from behind, a conical and laminated projection named 

 the pyramid (p), is first met with. In front of that is another smaller 

 projection, called the icrukt (u), Avhich is placed between the two rounded 

 lobes at the sides of the vallecula, named the amygdala (removed at 

 p, v) ; these terms having been suggested by a comparison with tho 

 parts so named in the throat. Between the uvula and amygdalte on 

 each side, but concealed from view, is extended a ridge of grey matter 

 indented on the surface, and named the furrowed Mnd. Still further 

 forward is the anterior pointed termination of the inferior vermiform 

 process, named the nodule (above n), which projects into the fourth 

 ventricle, and has been named the laminated tubercle (Malacarne). On 

 each side of the nodule is a thin white lamella of a semilunar form, 

 which is attached by its posterior convex border, and is free and con- 

 cave in front {}) v). The outer ends of these lamella? are attached to 

 the flocculi, and the inner ends to the nodule, and to each other in 

 front of that projection. The two lamelltB together constitute the ])os- 

 terior medullary velum, which has been compared with the valve of 

 Vieussens, — the one being attached to the superior extremity and the 

 other to the inferior extremit}^ of the middle or vermifonn portion of 

 the cerebellum. This posterior velum is covered in and concealed 

 by the amygdalae, and cannot be properly seen until those lobules have 

 been turned aside or removed, as in the figure (see also fig. 384). 



Internal Structure. — The central part is composed of white 

 matter, which sends out spreading and gradually thinning layers into 

 the interior of all the lamina?, larger and smaller, of the grey substance 

 which form a continuous covering on the surface. In consequence of 

 this arrangement of the white and grey substances, sections of the 

 cerebellum crossing the laminae, and dividing the grey and white sub- 

 stance together, present a beautifully foliated or arborescent appear- 



Fig. 363. Fig. 363.— Outline Sketch of a Ver- 



tical Section of the Cerebellum 

 TO show the Corpus Dentatum in its 

 Medullary Stem. (Allen Thomson.) § 



The section has been carried through 

 the left lateral part of the pons so as to 

 divide the superior ijeduncle and i^ass 

 nearly through the middle of the left 

 cerebellar hemisi>here. Tlie olivarj' body 

 has also been divided longitudinally so as 

 to expose in section its corpus dentatum. 

 cr, crus cerebri ; /, fillet ; q, corpora 

 quadrigemina ; sp, superior i^eduncle of 

 the cerebellum divided ; in "p, middle 

 peduncle or lateral part of the pons Varolii, with fibres passing from it into the white 

 stem ; « v, continuation of the white stem radiating towards the arbor vitoe of the folia J 

 C d, corpus dentatum ; o, olivary body with its corpus dentatum ; p, anterior pyramid. 



