THE HIND-BRAIN. 



687 



latera, grooves. Here, as on the upper surface, there are deep fissures, dividin* it 

 into separate segments or lobes, but the arrangement is more complicated, and die 

 relation of the segments of the worm to those of the hemisphere is less clearly 

 marked. The fissures are three in number, but are not so regularly disposed as 



Post-nodular fissure 



Flocculus. 



Pre- 



pyramidal 



Great 



horizontal 



fissure. 



Post- 

 pyramidal 

 fissure. 



FIG. 364. Under surface of the cerebellum. (Schafer.) 



those on the upper surface (Fig. 365). They are named, from their relation to the 

 pyramid and nodule, two of the lobes on the under surface of the worm, (1) post- 

 nodular, (2) pre-pyramidal, and (3) post-pyramidal fissures. The part of the worm 

 in front of the post-nodular fissure is termed the nodule, and the lobule in the hemi- 

 sphere corresponding with this is the flocculus. The next lobe is situated between 



FIG. 365. Diagram showing fissures on under surface of the cerebellum: F., flocculus; N., nodule ; U, uvulu : 

 P>'-. pyramid ; Am., amygdala ; Bivent., biventral lobe. 



the post-nodular and pre-pyramidal fissures. In the vermiform process it is known 

 as the uvula, and its lateral expansion in the hemisphere is named the amygdala 

 or tonsil. The lobule of the worm between the pre- and post-pyramidal fissures 

 is the pyramid, and its corresponding part in the hemisphere is the biventral or 

 digastric lobe. Finally, behind the post-pyramidal fissure in the worm is a small 

 lobe, the tuber valvulce or t uber posticum ; this, in the hemispheres, expands into a 

 large lobe, which occupies at least two-thirds of the inferior surface of the cerebel- 

 lum, and is subdivided into two by a secondary fissure, named the post-gracile 



