410 JOHN H. STOKES 



at an upwardly directed angle, to reach the tuberculum acousticum 

 which lies above and medial to the ventral nucleus. 



The tuberculum acousticum, or dorsal cochlear nucleus, pre- 

 sents the appearance of an elongated mass of cells uniting the 

 extremities of two peduncle-like fiber tracts, the one lateral and 

 posterior, the other medial and anterior; the former consisting of 

 those entering fibers of the N. cochlearis which are distributed to 

 the tuberculum acousticum, and the latter of the dense strands of 

 fibers constituting the olivo-cochlear tract, which pass downward 

 from the tuberculum acousticum towards the superior olive and 

 the nucleus corporis trapezoidei. The anterior end of the dorsal 

 cochlear nucleus is separated from the ventral nucleus, which at 

 this point lies lateral to it and in the same horizontal plane, by a 

 deep notch, completely filled by the fibers of the nucleo-cerebellar 

 tract of the vestibular nerve, as they pass upward toward the 

 cerebellum. At the point where the N. cochlearis enters the tuber- 

 culum, the nuclear mass spreads out in the shape of a mushroom, 

 becoming continuous on the dorsal surface of the restiform body 

 with the corpus ponto-bulbare, already described. The larger 

 part of the ganglion mass of the tuberculum lies at the point of 

 entrance of the cochlear fibers, just lateral to the spinal tract of 

 the vestibular. The remainder of the nucleus forms a bridge 

 over the spinal vestibular tract, merging into the olivo-cochlear 

 tract on the medial side. The tuberculum thus "straddles" 

 the spinal vestibular, so to speak, the nerve forming one leg and 

 the olivo-cochlear tract the other. The long axes of the two 

 cochlear nuclei present a characteristic inclination to each other, 

 that of the ventral nucleus being horizontal and extending antero- 

 posteriorly, that of the dorsal being oblique and extending for- 

 ward, downward and inward. 



Of the central connections of the two cochlear nuclei, the olivo- 

 cochlear tract has been described above. The figures from the 

 model, owing to the necessity of representing a group of strands 

 as a solid tract, give a somewhat exaggerated idea of its calibre, 

 which however, may be corrected from the sections. The cor- 

 pus trapezoideum or ventral path, is readily seen as a broad strip 

 on the ventral and ventro-lateral surfaces of the unsectioned 



