544 



THE NERVOUS SYSTEM 



bellar cortex with the cells of the pontine nuclei; some are afferent, some 

 efferent; some end in the gray matter of the pons on the same side near the 

 ventral surface; others cross to the opposite side of the pons and then 

 become longitudinal, passing on to the tegmentum. 



2. Fibers longitudinal in direction are arranged in hrger or smaller bundles 

 and are separated by gray matter. Most of these fibers are pyramidal fibers 

 which pass down to the pyramids of the medulla. 



3. The dorsal portion of the pons is made up to a considerable extent of the 



FIG. 381. Scheme to Show the Connections of the Posterior Longitudinal Bundle. (Cun- 

 ningham, modified from Held.) 



reticular formation of the tegmental region together with one or two distinct 

 bundles of longitudinal fibers. The chief longitudinal bundle, situated at the 

 junction of the ventral two-thirds with the dorsal third, is the fillet, including 

 a the larger mesial fillet, a sensory tract previously described arising in the 

 gracile and cuneate nuclei, and by the lateral fillet, an auditory tract. The 

 second, the posterior longitudinal bundle, is situated on each side of the mid- 

 line, just internal to the mesial fillet. 



4. In the upper part of the pons a mass of gray matter containing pigment, 

 the locus ceruleus, forming a part of the origin of the fifth nerve and in the 

 back part a second mass of gray matter, the superior olive. 



