MEDULLA OBLONGATA AND TEGMENTUM OF THE PONS. 



387 



ganglion in man, in animals often very large, situated between the cere- 

 bellum and pons, dorso-lateral from the cochlear nucleus. This is the 

 tuberculum acusticum. This portion also arborizes around cells. And so the 

 primary neviron of the cochlearis terminates in these two places. 



From the two primary termini arises a new fiber-tract, which in its 

 secondary and tertiary prolongation reaches eventually the lateral lemniscus, 

 or, rather, forms this lemniscus. 



1. The cells of the nucleus ventralis send out their axis-cylinders 

 toward the median line, where they are seen to leave the center as a strong 

 bundle. This tract is called the corpus trapezoideum. It lies directly dorsal 

 to the pontile fibers, and in animals, because their pons is shorter than in 

 man, is visible free on the base of the brain {vide Fig. 246). 



Within the trapezoid body are scattered large cells, nucleus trapezoideus 



Fig. 246. — Medulla oblongata and pons of a monkey, demonstrating the corpus 

 trapezoideum or trapezium, ct. a, Pyramids. 



(KoUiker), whose axis-cylinders take the same direction as the thick trape- 

 zoid fibers of the cochlear nucleus. 



The entire, rather important mass of fibers extends to a small group of 

 ganglion-cells, the superior olivary nucleus, and as much to the same side as 

 by decussation to the opposite side (Fig. 245). And here, seemingly, the 

 secondary auditory neuron ends. To the upper olive come the fibers of the 

 lateral fillet, a dense arborization. In this way connection between the 

 acusticus and the posterior, perhaps also the anterior, corpora quadrigemina 

 is established. 



Degeneration changes (Bumm, Baginski) make it appear that not only 

 the fillet-fibers descending here give off a great many collaterals around the 

 upper olivary nucleus, but also that from this nucletis itself, from the 

 nucleus trapezoideus, and from the striffi acusticaa, presently to be described, 

 pass numerous tracts of fibers into the fillet, and extend upward with it to 



