THE NERVOUS SYSTEM 503 



EXPLANATION OF FIG. 339 



Fig. 339. — Principal Connections of the Vestibular Portion of the Auditory (VIII) 

 Nerve. A, Section at level of oculomotor (III) nerve; B, section through pons and cere- 

 bellum; C, through inferior olives; D, through spinal cord. Each neurone group is 

 indicated by one or several individual neurones. 



Neurone No. i. — -Cell bodies in ganglion of Scarpa; peripheral processes end in semi- 

 circular canals; central processes bifurcate, and ascending arms go to Deiters' nucleus 

 (Nu. lal. 11. veslib.) (i a), to von Bechterew's nucleus {Nu. sup. n. veslib.) (i h), and 

 to nuclei fastigii and cortex of vermis of cerebellum (i c); descending arms go to nucleus 

 of descending root {Nu. n. vestib. desc.) (1 d) and (collaterals?) to principal or median 

 nucleus {Nu. med. n. vestib.) (i e). 



Neurone No. 2. — Axones of some cells in Deiters' nucleus descend {Tr. desc. nu. 

 Deilersi) uncrossed to antero-lateral column of the cord, axones of other cells enter the 

 posterior longitudinal fasciculus {Fasc. long, post., 2 b) of same side and descend to 

 anterior column of the cord, others pass to the medial longitudinal fasciculus of opposite 

 side whence some (2 c) descend to anterior column of the cord, occupying a position near 

 the anterior median fissure, while some (2 d) ascend in the medial longitudinal fasciculus 

 and terminate principally in the nuclei of VI, IV, and III nerves. Axones of cells in von 

 Bechterew's nucleus ascend (2 e), joining lateral part of medial longitudinal fasciculus of 

 same side, and terminate in nuclei of IV and III nerves. Axones of cells in the nucleus 

 of the descending root probably pass in part to lateral part of reticular formation of same 

 and opposite sides, ascending and descending (to other motor nuclei?). Axones of cells 

 in the median nucleus probably pass largely into the reticular formation, possibly also to 

 the medial longitudinal fasciculus (not indicated). Axones of cells in the nuclei fastigii 

 of the cerebellum pass to von Bechterew's nucleus (2/) and to Deiters' nucleus (2 g). The 

 cerebellar associations intercalated between these (2/, 2 g) and the vestibular fibres to 

 the cerebellum (i c) are not known. (It is evident that impulses other than vestibular 

 ones entering the cerebellum may also by 2 /and 2g act indirectly upon the motor nuclei 

 innervated by axones of the cells in Deiters' and von Bechterew's nuclei. Compare 

 Figs. 331 and 345.) 



