300 



PRACTICAL ANATOMY. 



and then pass to the cerebellum and form its inferior 

 peduncles. 



The pons Varolii is the great commissure at the base 

 of the brain, connecting the hemispheres of the cerebel- 

 lum with the cerebrum and medulla. It rests on the 

 basilar process of the occipital and os planum of the 

 sphenoid, and presents an inferior convex surface, a supe- 



FIG. 131. MEDULLA OBLONGATA, PONS, CEREBELLUM, AND CRURA 

 CEREBRI, SEEN FROM IN FRONT. 



rior and inferior border. The borders are sharply defined, 

 the anterior curved from side to side, the inferior 

 slightly concave. The inferior surface presents a median 

 longitudinal groove, in which rests' the basilar artery. 

 About one inch on either side of the median groove is 

 the origin of the fifth pair of nerves nearer the anterior 

 than the inferior border. Externally the pons narrows 

 and enters the cerebellum, forming its middle pe- 



