Cerebellum. 113 



454. Tlie Cerebellum, view from above. Natural size. 



The superior peduncles of the cerebellum, Processus e 

 cerebello ad testes (Processus cerebelli ad corpora quadrigemina), pass from the 

 hemispheres of the cerebellum to the Corpora quadrigemina ; they form 

 part of the lateral boundaries of the fourth ventricle. Between the con- 

 verging crura of the superior peduncles, the anterior medullary 

 velum or valve of Vieussens, Velum medullare anterius s. Valvula 

 cerebelli, is stretched, covering the canal leading from the third to the 

 fourth ventricle (see Fig. 453). 



At the upper surface, the two hemispheres of the cerebellum 

 are connected by the superior vermiform process, Vermis superior, 

 corresponding to whose anterior and posterior extremities are two notches, 

 the Incisura marginalia anterior and posterior. 



The upper surface is separated from the lower by the deep Sulcus 

 magnus norizontalis. In each hemisphere there are : 



a) The a n t e r o - s u p e r i o r or square lobe, Lobus superior 

 anterior s. quadrangular is, then 



b) The p o s t e r o - s u p e r i o r or semilunar lobe, Lobus supe- 

 rior posterior s. semilunaris. 



The parallel gyri of the Vermis superior separate the following 

 three structures : 



a) The central lobe, Lobulus centralis, which has a central portion 

 and two alae; 



b) The Mbnticulus, whose highest point, Cacumen, is continued 

 posteriorly into the Declive; a) and b) as connections of the gyri of 

 the anterior lobe ; 



c) The Folium cacuminis, situated in the Incisura marginalis posterior, 

 connecting the posterior lobes. 



