THE CEREBELLUM 



197 



sembles a worm bent on itself to form almost a complete circle; and two large 

 lateral masses, the cerebellar hemispheres, which are connected with each other 

 by the verrm's (Figs. 138, 139). Although morphologically incorrect, this sub- 

 division has the advantage of convenience as well as of established usage. On 

 the rostral aspect of the cerebellum the vermis forms a median ridge, not sharply 

 marked off laterally from the hemispheres. This part has been called the superior 

 vermis, and in contradistinction the remainder is known as the inferior vermis. 

 The latter forms a prominent ridge, marked off from the hemisphere on either 

 side by a well-defined sulcus. It lies in a deep groove between the hemispheres, 

 known as the vallecula, within which the medulla oblongata is lodged. The 

 hemispheres are also partially separated from each other by deep notches, the 



Anterior cerebellar notch 



Central lobule 

 f Ala of central lobule 



Quadrangu-$ Ant, portion 

 lar lobule \p os t. portion 



Cerebellar hemi- 

 sphere superior 

 surface 



Superior semi- . 

 lunar lobule 



Cerebellar folia 

 Inferior semilunar lobule 



Primary fissure 



Postclival sulcus 

 Horizontal cerebellar sukus 



Folium of vermis 

 Posterior cerebellar notch 



Fig. 138. Dorsal view of the human cerebellum. (Modified from Sobotta-McMurrich.) 



incisura cerebelli. The anterior cerebellar notch (semilunar notch) is broad and 

 deep; and as seen from above it is occupied by the brachia conjunctiva and 

 the inferior colliculi of the corpora quadrigemina. The posterior cerebellar 

 notch (marsupial notch) is smaller, and within it is lodged a fold of the dura 

 mater, the falx cerebelli. 



The superior vermis is divided by transverse fissures into the following 

 lobules (Fig. 138): 



1. Lingula, closely applied to the anterior medullary velum between the two 

 brachia conjunctiva. 



2. Central lobule, associated with the small alae lobuli centralis of the hemi- 

 sphere. 



