GRAY MATTER OF MEDULLA. 309 



in the nuclei of motor nerves; second, with spinal nerves by the 

 axones of Purkinje's cells to the nucleus fastigii and nucleus glo- 

 bosus; from the cerebellar ganglia by the acustico-cerebellar 

 tract to the nucleus of Deiters, and then by way of the anterior 

 descending cerebello-spinal tract to the motor nuclei of the spinal 

 nerves in the anterior columna. 



Cochlear Nuclei (Nn. Nerui Cochlearis, Fig. 92). There are 

 two cochlear nuclei, the ventral and the lateral. They concern 

 hearing proper. The ventral cochlear nucleus appears in section 

 as a triangular mass of cell-bodies imbedded hi the medulla at 

 the upper end of the posterior lateral sulcus. It lies between the 

 restiform body and the olive; the vestibular root of the auditory 

 nerve separates it from the olive. It receives the greater number 

 of fibers in the cochlear nerve and gives rise to those of the trap- 

 ezoid body and, through that, to a large part of the lateral fillet 

 of the opposite side ; a few of its fibers enter the fillet of the same 

 side. In the corpus trapezoideum, the cochlear tract is largely 

 relayed by the neurones forming the nuclei of the superior olivary 

 group. The lateral cochlear nucleus embraces the outer surface 

 of the restiform body. It is situated both lateral and dorsal to 

 the ventral nucleus and, stretching around the posterior surface 

 of the restiform body, it produces the ventricular eminence in 

 the lateral part of the acustic area, called the tuberculum acusticum. 

 The lateral nucleus receives that part of the cochlear root which 

 does not end in the ventral nucleus, and the fibers arborize about 

 its cells. The axones of the lateral nucleus form the medullary 

 striae; a few of them enter the trapezoid body (Figs. 86, 89 and 92). 

 The medullary striae run somewhat obliquely across the ventric- 

 ular floor to the median groove, plunge forward to the superior 

 olivary nuclei of the opposite side where they are partially relayed 

 and then, bending upward, are continued in the lateral fillet. 

 At the superior olivary nuclei of the opposite side the fibers from 

 the lateral and ventral nuclei become intermingled, hence the 

 trapezoid body and medullary striae combine in the formation of 

 the lateral fillet. The lateral fillet suffers a partial relay in its 

 own nucleus, after which it separates into two parts; the prin- 

 cipal part runs to the internal geniculate body, by way of the 



