ORIGIN OF THE CEREBRAL NERVES. 501 



110 extensive immediate connection of the auditory nerve with 

 the cerebral lobes exists, but that such a connection, the exist- 

 ence of which may be assumed as a necessary physiological 

 truth, can only come to pass indirectly through the cerebellum. 



Amongst such connecting cords sent forth by the cerebellum, 

 we can only suppose that the inferior peduncle of the cerebellum 

 or the medullary velum joining with the frenulum of the corpora 

 quadrigemina may prove to be the one. Should it be here- 

 after shown that this peduncle its size corresponding to that 

 of the optic nerve is the tract connecting the auditory nerve 

 with the cerebrum, the decussation of the tegmentum would 

 have the significance of a chiasma of the auditory sense. 



The origin of the auditory nerve, however, embraces the fol- 

 lowing sets of fibres, proceeding in part from the above-named 

 nuclei. 



In the first place, we must distinguish an anterior principal 

 root running through the pons in front of the crus cerebelli, 

 from a posterior principal root, which includes the strise 

 medullares, and embraces the crus cerebelli with its most 

 external fasciculi. 



The collected fasciculi of the anterior root run with a height 

 of two millimeters, and a breadth of one millimeter, between the 

 corpus restiforme and the ascending root of the fifth, and are 

 composed of decussating and non-decussating fasciculi of origin. 



1. The decussating fasciculi are the most internal of those 

 forming the anterior root, and arise apparently from the inner- 

 most auditory nucleus of their own side. These fasciculi of 

 origin, however, which, extending transversely from the raphe, 

 traverse the internal auditory nucleus and the fasciculi of the 

 internal division of the cerebellar peduncle of the same side, 

 pass in a twofold form from the internal division of the 

 opposite cerebellar peduncle. In their first mode of running 

 they pass from the crus cerebelli, through the internal audi- 

 tory nucleus, in a line which can be drawn through the 

 auditory rod of Bergmann, or rather through several ascend- 

 ing auditory strice of J. Engel (and thus down to the 

 inner extremity of the transverse striae medullares), partly 

 superficially in the form of the above-named formations, 

 partly more deeply situated (in front of the genu of the facial 



