THE BRAIN STEM. 



257 



from below (coming from the spinal cord) or from above (com- 

 ing from the cerebrum). They then transmit these impulses 

 along their own nerve fibers, which may run to various other 



Fig. 45. Under aspect of human brain. In the center line from below 

 upwards are seen a section of the upper end of the spinal cord, and the 

 medulla oblongata (m), with certain of the cranial nerves (as numbered). 

 In front of this is the pons (p), with the large fifth nerve arising from it, 

 and the middle peduncles of the cerebellum (M. Fed) running into the cere- 

 bellum (A). The rounder bodies anterior to the pons are the corpora quad- 

 rigemina (Cq), to the sides of which are the crura cerebri and the origins of 

 the third and fourth nerves. The optic and olfactory nerves are in front. 

 The under surfaces of the cerebrum (Cb) and cerebellum (A) constitute 

 the remainder of the drawing. ( From a preparation by P; M. Spurney. ) 



