ORIGIN OF CEREBRAL NERVES. 323 



fibers of the formatio reticularis, in the pons and mid-brain, and, 

 in the hemisphere, by certain fibers of the internal capsule which 

 end hi the fusiform gyrus (?). The cochlear nuclei (ventral and 

 lateral) receive true impulses of hearing and conduct them on to- 

 ward the cerebral cortex by way of their axones, which form the 

 trapezoid body and medullary striae and then unite in forming 

 the lateral fillet (Fig. 89). The remaining links of the cortical 

 connection are formed by the brachium inferius and the acustic 

 radiation (radiatio temporothalamica). The reflex connection 

 of these nuclei is somewhat indirect. It is established in part by 

 certain fibers of the lateral fillet which end in the quadrigeminal 

 colliculi, together with the anterior longitudinal bundle; but is 

 chiefly brought about by the olivary pedicle and the me- 

 dial longitudinal bundle. The -vestibular nuclei the principal 

 (Schwalbe's), Deiters's and the nucleus of the descending root 

 concern equilibrium. They receive impulses from the vestibule 

 and semicircular canals of the internal ear. They have ^.-cerebral 

 and a cerebellar cortical connection. The former is established 

 as far as the thalamus, by the opposite medial fillet, and com- 

 pleted by the cortical fillet; and the latter is formed by the de- 

 scending root, which ends in the nucleus funiculi cuneati, and the 

 external arcuate fibers. With the cerebral motor nerves, these 

 nuclei are brought into reflex connection, first, by axones entering 

 the medial longitudinal bundle and terminating in the motor 

 nuclei; and, second, probably by fibers of the brachium conjunc- 

 tivum which become connected with the nuclei of the third, fourth 

 and sixth cerebral nerves. The reflex connection with spinal 

 nerves is formed by the anterior descending cerebello-spinal tract, 

 viz., by axones of Purkinje's cells, the acustico-cerebellar tract, 

 the cerebello-olivary fibers and descending fibers from Deiters's 

 and the inferior oh" vary nuclei. 



The terminal nuclei of the optic nerve are situated in the lateral 

 geniculate body, the pulvinar of the thalamus and the superior 

 colliculus of the corpora quadrigemina (Fig. 43). Like the ter- 

 minal nucleus of the olfactory nerve, these cannot at present be 

 included in the posterior columna series, because the ventral and 

 dorsal zones of the embryonic fore-brain have not been sufficiently 



