188 



LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



In the prolongation of the line of exit of the anterior roots, 

 between the olivary bodies and the pyramids, the hypoglossal 

 nerve {XII) emerges from the medulla obldngata. The spinal 

 accessory nerve of Willis (XI) arises by numerous radicles, 

 which are given off along the side of the cervical cord, and 

 high up in the oblongata, external to the olivary bodies. Above 

 and in line with it emerge the vagus (X) and the glosso- 

 pharyngeal {IX). Laterally, close behind the fibres of the 





fi.cerv. 



FIG. 113. 



Medulla oblongata, pons, cerebellum, and pedunculns cerebri seen from in front. To 



show the origin of the cranial nerves. 



pons, are given off the acoustic ( VIII) and the facial nerves 

 ( VII). The sixth cranial nerve, the abducens, lies internal to the 

 point of origin of the two last mentioned. The trigeminus ( V) 

 arises from the depths of the pons. The origins of the trochlear 

 (IV) and the oculo-motor (///) have already been given. The 

 first emerges from the velum medullare posticum behind the 

 corpora quadrigemina, and the second from the ventral surface 

 of the pedunculi cerebri. 



