476 THE BRAIN OF MAMMALS, BY TH. MEYNERT. 



But the circumstance that the corpus restiforme, or external 

 division of the peduncle of the cerebellum, as it proceeds from 

 above downwards (fig. 257, MFC ; in fig. 258, the continuation 

 of Z lying behind 8) becomes exhausted, and vanishes, in pro- 

 portion as the cross section of the cuneate and slender columns, 

 i.e., the posterior column, increases (fig. 258, H, that is, Cn + Or), 

 justifies and even necessitates the view that in these two sec- 

 tional areas we have different portions of the course of a con- 

 tinuous tract, viz., a decussating mode of origin of the poste- 

 rior column from the cerebellum. Preserving the idea of 

 Deiters as a groundwork, the following view of this connection 

 appears to me to be justified. 



There are two courses pursued by these fasciculi of origin of 

 the posterior column in the medulla oblongata. 



1. The external and middle fibrse arcuatse proceeding from 

 the corpus restiforme are analogous to the corpus trapezoides of 

 the superior olivary body. Having arisen from the cerebellum, 

 they invest on the one hand the transverse section of the fifth 

 () and the olivary body as the stratum zonale ; and upon the 

 other hand they perforate both the transverse section of the 

 fifth and the olivary body, without, however, being connected 

 with the nerve corpuscles of the latter. At the same time, as 

 transverse fasciculi they include small nerve corpuscles within 

 the transverse section of the fifth, and are continuous with the 

 clusters of the motor area (nucleus of the lateral column). 



sion of the motor 'area (anterior column) ; MFE, external division of 

 the motor area (lateral column) ; G, gelatinous substance ; S, fasciculi 

 in and around the gelatinous substance, which are the ascending roots 

 of the fifth ; As, fibres arcuatae that are continuous with the internal 

 division of the peduncle of the cerebellum ; Am, fibrae arcuatae con- 

 tinuous with the outer division of the same peduncle ; XII, roots of 

 the hypoglossus ; X, rootlets of the vagus traversing the gelatinous sub- 

 stance ; the X beneath the grey floor indicates portions of the latter 

 that emerge from the raphe in connection with the roots of the hypo- 

 glossal ; X 1 , fasciculi from the posterior columns of origin of the vagus ; 

 JT 2 , the anterior nucleus of the vagus, with fasciculi curving round in 

 the rootlets of the vagus beneath the grey floor ; X 4 , fasciculi which, 

 proceeding from the raphe beneath the epithelium of the grey floor, 

 run round and through the eminentia teres ; X 3 , median nucleus ; 

 VIII, fasciculus belonging to the auditory nerve (Clarke). 



