INFERIOR SURFACE OF THE CEREBELLUM. 251 



Declive and Posterior Parts of Quadrangular Lobules, Lo- 

 bus Declivis (Figs. 76 and 79). The declive monticuli forms the 

 posterior slope, as the culmen forms the summit, of the monticulus 

 cerebelli. The declive has about half the extent of the culmen. 

 Its gyri are continued into either hemisphere, where they form 

 a large crescentic lobule, the pars posterior lobuli quadrangular is. 

 The increased size of the lobe in the hemisphere is due to the 

 expansion of the secondary gyri found in the worm. The anterior 

 and posterior parts of the quadrangular lobule constitute the 

 lobulus quadrangularis, which forms the anterior two-thirds of 

 the tentorial surface of the hemisphere. The declive and its 

 hemispheral extensions are inclosed between the predeclivil 

 and postdeclivil sulci. 



The folium vermis and superior semilunar lobules, lobus 

 folii vermis (Figs. 76 and 79), lies behind the postdeclivil and 

 above the horizontal sulcus. The folium vermis is the terminal 

 lobule in the superior worm, and occupies the posterior cerebellar 

 notch. It appears near birth in the bottom of a transverse groove 

 common to the postdeclivil and horizontal sulci (Cunningham). 

 Rarely it is absent. It contains a single medullary lamina beset 

 with rudimentary gyri, which are largely developed in the hemis- 

 pheres. The superior semilunar lobule is, therefore, very large 

 in comparison with the folium vermis. It expands lateral ward 

 to the postero-lateral border of the hemisphere, which it forms. 

 It comprises the posterior third of the hemisphere's tentorial 

 surface, and forms one of the remarkable features of the human 

 cerebellum. 



INFERIOR SURFACE OF THE CEREBELLUM. 



The inferior surface of the cerebellum (fades cerebelli inferior) 

 is prominent laterally and depressed centrally (as the organ is 

 viewed inverted), the hemispheres being separated by the antero- 

 posterior groove, called the vallecula cerebelli (Figs. 77 and 80). 

 The vallecula (little valley) is occupied by the inferior -worm and 

 is bounded on either side by a small cleft, 'bet ween the worm and 

 the overhanging hemisphere, called the sulcus vallecula. The 



