THE STRUCTURE OF THE BRAIN STEM 



429 



The vestibular nerve (Fig. 195) also has two nuclei of termination, 

 the median nucleus with small cells, and the lateral or Deiters' nucleus 

 with large cells. Some fibres pass also to the nucleus of Bechterew, 

 which is in close relation with the roof nuclei of the cerebellum. The 

 descending fibres end chiefly in the median nucleus, while the ascending 

 fibres end in Deiters' nucleus. From the latter a distinct band of 

 fibres passes up to the cerebellum, forming the median division of the 



TO VERMIS 



TO HEMISPHERE 



FIBRES OF 

 VESTIBULAR 

 ROOT 



NERVE 

 ENDINGS 

 IN MACUL/E 

 & AMPULL/E 



GANGLION OF 

 SCARPA 



FIG. 195. Plan of the course and connections of the fibres forming the 

 vestibular root of the auditory nerve. (SCHAFER.) 



r, restiform body ; V, descending root of fifth nerve ; p, cells of principal 

 nucleus of vestibular root ; d, fibres of descending vestibular root ; nd, a cell 

 of the descending vestibular nucleus ; D, cells of nucleus of Deiters ; B, cells 

 of nucleus of Bechterew ; nt, cells of nucleus tecti (fastigii) of the cere 

 bellum ; plb, fibres of posterior longitudinal bundle. No attempt has been 

 made in this diagram to represent the actual positions of the several nuclei. 

 Thus a large part of Deiters' nucleus lies dorsal to and in the immediate 

 vicinity of the restiform body. 



restiform body, while other fibres run across to the tegmentum of the 

 opposite side, where they take part in the formation of the posterior 

 longitudinal bundle. 



In a section through the fourth ventricle through the middle of 

 the pons, a group of large cells is seen in the position occupied by the 

 nucleus of the hypoglossal below. These cells give rise to the fibres 

 of the sixth nerve. Another group is seen lying laterally and more 

 deeply, evidently belonging to the lateral horn system. This is the 

 nucleus of the seventh or facial nerve, the fibres of which pass dorsally 

 and anteriorly, looping round the sixth nerve-nucleus, before issuing 

 as the root of the seventh nerve. 



