324 



AISTATOIIY OF THE CENTBAL KESTOUS SYSTEM. 



anterior peduncles enter the cerebellum, one will find dorsally the cerebel- 

 lum, ventrally the pons and the fibers which pass from it on both sides into 

 the hemispheres. Between the cerebellum and the tegmentum, bounded on 

 either side by the divided peduncles, lies the fourth ventricle, which is the 

 widened continuation of the aqiieduct of Sylvius. The medullary substance 

 of the vermis does not lie in the plane of the section. The tegmentum and 

 the pes, the latter traversed by the pontal fibers, lie in the same relative posi- 

 tions as when seen in sections through the region of the corpora quadri- 

 gemina. 



"We have found that fibers pass through the three pairs of peduncles 

 into the cerebellum. Their cotirse within the cerebellum is still very imper- 





Fig. 210. — Frontal cerebellar section just anterior to the culmen. U, Ven- 

 triculus quartus. R, Anterior peduncle. P, Pons. Zon, Decussation-zone. Cr., 

 Fibers from corp. rest, passing to l^cni, the flbrse semieirculares. (After B. 

 Stilling.) 



fectly known, notwithstanding the fact that Benedict Stilling has devoted 

 long years of work to the study. 



However, the work of the last few years, especially that directed to the 

 tracing of degenerations which follow a total or partial extirpation of the 

 cerebellum, has furnished a large member of important facts regarding the 

 topography. So it is at last possible to elucidate the origin of the separate 

 arms. 



The diagram given in Fig. 211 shows upon the frontal sections, through 

 those portions of the central nervous system which are in immediate asso- 

 ciation with the cerebellum, the most important facts at present known 

 regarding the connections of the cerebellum. 



