CH. XLVI.] 



THE EIGHTH NERVE 



677 



tubercle pass superficially over the floor of the ventricle, forming the 

 stria acoustics; having crossed the raphe, they join the fibres from the 

 accessory nucleus in their course to the superior olive and fillet. 

 Here again, however, a few fibres pass to the fillet of the same side. 



The vestibular nerve arises from the bipolar cells of the ganglion 

 of Scarpa, which is situated in the internal auditory meatus. The 

 peripheral axons ramify among the hair cells of the epithelium in the 

 utricle, saccule, and semi-circular canals. The central axons enter a 

 collection of small nerve- cells between the restiform body and the 

 descending root of the fifth ; this is termed the principal nucleus ; here 



TO VERMIS 



TO HEMISPHERE 



FIBRES OF 

 VESTIBULAR 

 ROOT 



NERVE 

 ENDINGS 

 IN MACUL/E 

 &AMPULL/E 



FIG, 417. Vestibular division of the auditory nerve, r, Restiform body ; V, descending root of the fifth 

 nerve ; d, libres of descending vestibular root ; n.d., cell of descending vestibularnucleus ; D, nucleus 

 of Deiters ; B, nucleus of Bechterew; n.t., nucleus tecti of cerebellum : p.l.b., posterior longitudinal 

 bundle. (Schiifer.) 



they bifurcate ; the descending branches run towards the lower part of 

 the bulb, and arborise around the cells of the neighbouring grey matter 

 (descending vestibular nucleus). The ascending branches pass upwards 

 in the restiform body to the cerebellum, in their course giving off many 

 collaterals which form synapses with the large cells of two nuclei 

 near the outer angle of the ventricular floor, and known as the 

 nucleus of Deiters and nucleus of Bechterew respectively. The fibres 

 which arise from Deiters' nucleus pass into the posterior longitudinal 

 bundles of both sides (see p. 674) ; those which start in Bechterew 's 

 nucleus become longitudinal, but their destination is uncertain. 



The accompanying diagrams (figs. 416 and 417) will serve to render 

 these complex relationships clearer. 



