T1IK 



789 



of the posterior notch Ix'jrins, and here the horizontal and the posterior semilunar 

 fissures approach each oilier so closely that the corresponding subdivision of the 

 vermis is sclil more than a single folium, the folium vermis (cuciuninis). 



The UK nit iculus proper is divided into an inferior lolmlc, the clivus, and a superior 

 lobule, the culmen. These appear as continuations across the Olid-line of the pos- 

 terior and anterior crescent ic lobes of the hemispheres, and are separated by the 

 corresponding fissures. 



At the extreme anterior part of the dorsal surface and in the bottom of the an- 

 terior cerebellar notch lies a more definitely defined portion of the vermis. This 

 is the central lobule (lobe). It is broadened laterally into two pointed wings, the 

 alir of the central lobule, the folia of which, if present, are parallel with those of 

 the anterior semilunar lobes. 



If the anterior margin of the central lobule be lifted, the lingula cerebelli (lin- 

 gula vermis) will appear. It is a thin, tongue-like anterior projection of the cor- 



Fio. 585. MEDIAN SECTION THROUGH CEREBELLUM AND BRAIN-STEM. (Allen Thompson, 



after Reichert.) 



1, culmen monticuli; 2, superior semilunar lobe; 3, inferior semilunar lobe; 4, slender lobe; 



5, biventral lobe; 6, tonsil. 



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tical substance upon the anterior medullary velum, the roof of the superior portion 

 of the fourth ventricle. 



Ventral surface. The three cerebellar peduncles of each side join to form a 

 single mass of white substance, and enter the ventral aspect of each hemisphere at 

 the inner and ventral extremity of the horizontal fissure. The ventral and inferior 

 surface of the cerebellum is less convex than the dorsal surface. The hemispheres 

 are decidedly separated by a continuation of the posterior cerebellar notch, which 

 becomes broader and contains the inferior portion of the vermis, vermis inferior, 

 and whose margins embrace the medulla oblongata. The ventral surfaces of the 

 hemispheres are each divided by the intervening fissures into four lobes. 



Below, the inferior semilunar lobe (postero-inferior lobe) is separated from 

 the superior semilunar lobe of the dorsal surface by the horizontal fissure. It is the 

 largest of the ventral lobes, and is broader at its medial extremity. Frequently two 

 and sometimes three of its curved sulci appear deeper than others, and separate it 

 into two or three slender lobules, lobuli graciles. More commonly there are two 

 of these, the lohiilux iinn-ilis fioati rior and lolntlus gracilis trnUrii.r, separated by sulci 

 (fissures) correspondingly named. 



