686 THE NERVOUS SYSTEM. 



UPPER SURFACE OF THE CEREBELLUM. 



Worm. Hemisphere. 



Lingula. Frsenulum. 



Pre-central fissure. 

 Lobulus centralis. Ala lobuli centralis. 



Post-central fissure. 

 Culmen monticuli. Anterior crescentic lobe. 



Pre-clival fissure. 

 Clivus monticuli. Posterior crescentic lobe. 



Post-clival fissure. 

 Folium cacuminis. Posterior superior lobe. 



The lingula is a tongue-shaped process of the cerebellum, which lies in front of 

 the lobulus centralis and is partially or completely concealed by it. It is in rela- 

 tion, in front, with the valve of Vieussens, on 'the dorsal surface of which it rests 

 and with which it is connected ; its white matter being continuous with that of the 

 valve. At either side the lingula gradually shades oft', and is prolonged only for a 

 short distance into the hemispheres, where it forms the frsenulum. This does not 

 stretch beyond the superior peduncle of the cerebellum over which it lies. 



The Lobulus Centralis. The lobulus centralis is a small square lobe, situated in 

 the anterior notch. It overlaps the lingula and is in turn partially concealed by 

 the culmen monticuli. Laterally the lobulus centralis extends along the upper 

 and anterior part of each hemisphere, where it forms a wing-like prolongation, the 

 ala lobuli centralis. 



The culmen monticuli is much larger than the two lobes just described, and con- 

 stitutes, with the succeeding lobe, the clivus, the bulk of the upper worm. In front 

 it partially overlaps and obscures the lobulus centralis, and behind it is separated 

 from the clivus by the pre-clival fissure. It forms the most prominent part of the 

 upper worm, and is marked on its surface by three or four secondary fissures, 

 dividing it up into smaller lobules. Laterally it is continuous with the anterior 

 crescentic lobe of the hemispheres, which is distinctly differentiated from the poste- 

 rior crescentic lobe by the pre-clival fissure, though the two were formerly classed 

 together as the quadrate lobe of the lateral hemisphere. 



The clivus monticuli is of considerable size, and, as stated above, forms with the 

 culmen the major part of the superior worm. It consists of a group of laminae, 

 which in front are separated from the culmen by the pre-clival fissure and behind 

 appear to be almost continuous with the folium cacuminis, especially in the median 

 line ; but it will be found, on careful examination, to be separated from it by a 

 well-defined fissure, the post-clival fissure. Laterally this lobe is continued into 

 the hemispheres as the posterior crescentic lobe, which is somewhat semilunar in 

 shape, and, with the anterior crescentic lobe, constitutes the greater part of the 

 upper surface of the hemispheres. 



The folium cacuminis is a short and narrow, concealed band at the posterior 

 extremity of the worm, consisting apparently of a single folium, but in reality 

 marked on its upper and under surfaces by secondary fissures. Laterally it 

 expands in either hemisphere into a considerable lobe, which is semilunar in shape, 

 and is situated at the postero-superior part of the hemisphere and bounded below 

 by the great horizontal fissure. It is named the posterior superior lobe and occupies 

 the posterior third of the upper surface of the hemisphere, forming its rounded 

 postero-lateral border. 



The Under Surface of the Cerebellum (Fig. 364) presents in the middle line the 

 inferior worm, buried in the vallecula, and separated from the hemispheres by 



