PATHS OF THE CRANIAL NEKVES 547 



about the cells of the mesial or chief nucleus, a large area in the 

 floor of the fourth ventricle containing small scattered nerve cells ; 

 it is comparable to the chief nuclei of the ninth and tenth nerves. 

 2. Other fibres, probably for the most part ascending branches, pass 

 to the superior vestibular nucleus (von Bechterew's nucleus), which 

 is situated in a more dorsal and lateral plane and somewhat cephal- 

 ad, from the mesial nucleus. 3. Other fibres end about the large 

 cells of the lateral vestibular nucleus (Deiters' nucleus). 4. Still 

 other fibres, mostly descending branches, pass caudad, as the de- 

 scending or spinal root of the vestibular nerve, which passes down 

 the medulla in the restiform body, following a course parallel, but 

 lateral, to the tractus solitarius. The fibres of the spinal root end 

 in relation to the nerve cells of the adjacent grey matter. 



From the nerve cells of the descending root, as well as from the 

 median and superior nucleus, neurones of the second order send 

 their neuraxes as internal arcuate fibres to the fillet of the opposite 

 side, through which they are continued toward the cerebrum. 



Neurones of the second order, which include the cells of Deiters' 

 nucleus, send their neuraxes caudad in a fairly compact bundle, 

 which finally joins the fasciculus sulco-marginalis of the spinal 

 cord, as already described. , 



The vestibular nerve is also directly connected with the cere- 

 bellum by paths which can only be followed with considerable 

 difficulty. Some neurones from the superior vestibular nucleus 

 (von Bechterew's) are thought to enter the cerebellum through the 

 superior peduncles. This group may, however, also contain per- 

 ipheral neurones which pass without interruption to the ver- 

 mis cerebelli. A second bundle enters the cerebellum through the 

 corpus restiforme and is probably derived from the cells of Deiters' 

 nucleus. 



The cochlear nerve, the path of the acoustic impulses, contains 

 neurones which begin as the bipolar nerve cells of the ganglion 

 spirale in the internal ear. The distal processes of these cells are 

 distributed to Corti's organ, their proximal branches collectively 

 form the root of the cochlear nerve. 



This nerve enters the medulla oblongata at the caudal margin 

 of the pons, along with, but somewhat dorsal to the vestibular nerve. 

 Near its entrance it passes into the cochlear nucleus, which it thus 

 divides into a dorso-lateral portion (dorsal cochlear nucleus or 

 tuber culum acusticum) and a ventro-mesial portion (acoustic nu- 

 cleus, ventral or chief cochlear nucleus). Its fibres divide into 



