416 MABEL BISHOP 



The dorsal, lateral, and ventral funiculi of the spinal cord and 

 medulla on the outer (normal) portions are clearly demonstrable 

 (figs. 13 to 19). 



Before leaving the normal area, however, there are certain 

 other fiber tracts that should be considered: A longitudinal fiber 

 tract, the fasciculus longitudinalis medialis, may be traced along 

 each side of the median raphe of each head rostrally from about 

 the level of the superficial origin of the normal seventh nerves 

 to and extending throughout the entire extent of the medulla 

 and mesencephalon (figs. 9 to 14). The fibers of the basal portion 

 of the cerebral peduncle, or ventral part of the mesencephalon 

 of each head, are conspicuous as they sweep upward from the 

 medulla and arch over the cephalic flexure on their way into the 

 diencephalon and hemispheres (fig. 8). Dorsally they form the 

 tegmentum, which constitutes the side walls and floor of the 

 aqueduct of Sylvius. 



Fibers of the posterior commissure are seen only in oblique 

 section, but the commissure is normal. 



In the conjoined regions. In the median region the central 

 connections of the cranial nerves are still more problematic, for 

 they involve tracing the peripheral fibers through the two 

 cranial nerve-masses into and through regions of the brain that 

 are distinctly teratological in form relations and size that adjust 

 topographically to the space available. The alterations of the 

 normal relationships of the quadrants in this median region from 

 the cord to the mesencephalon must ever be kept clearly in mind 

 if the normal pattern of the intracranial nerve fibers and fiber 

 tracts is to be recognized through the teratological relationships. 



Nerves one, two, three and four are not involved in the 

 problem. 



The rostral cranial nerve-mass, its associated nerves and fiber 



tracts 



At the level of the entrance of the median fifth nerve into the 

 rostral cranial nerve-mass, it is seen that juxtaposed dorsolateral 

 and ventrolateral quadrants form the median area, and the 



