484 THE NERVOUS SYSTEM. 



as in the convolutions of the cerebrum ; in other parts it is 

 deeply situated, as in the basal ganglia i. e., the corpora striata, 

 optic thalami, etc. (p. 499) ; while in still other parts it is scattered 

 about without any fixed arrangement, as in the pons Varolii. The 

 white matter is made up of fibers which come from the spinal 

 cord ; of fibers having their origin in the gray matter, and which., 

 escaping from the skull, go to their points of distribution as the 



FIG. 278. Base of brain : 1, 2, 3, cerebrum ; 4 and 5, longitudinal fissure : 6, 

 fissure of Sylvius; 7, anterior perforated spaces; 8, infundibulum ; 9, corpora albi- 

 cantia ; 10, posterior perforated space ; 11, crura cerebri ; 12, pons Varolii ; 13, junc- 

 tion of spinal cord and medulla oblongata ; 14, anterior pyramid ; 14 X , decussation 

 of anterior pyramid ; 15, olivary body ; 16, restiform body ; 17, cerebellum ; 19, 

 crura cerebelli ; 21, olfactory sulcus ; 22, olfactory tract ; 23, olfactory bulbs ; 24, 

 optic commissure ; 25, motor oculi nerve : 26, patheticus nerve ; 27, trigeminus 

 nerve ; 28, abducens nerve; 29, facial nerve; 30, auditory nerve; 31, glossopharyn- 

 geal nerve ; 32, pneumogastric nerve ; 33, spinal accessory nerve ; 34, hypoglossal 

 nerve. 



cranial nerves ; and of still other fibers connecting the ganglia 

 with one another, forming commissures. 



The Medulla Oblongata. The medulla oblongata, or bulb, is 

 the continuation of the spinal cord, and is about 2.5 cm. long, 2 cm. 

 broad, and 1.2 cm. thick. It is composed of gray and white matter. 

 The gray matter, which in the cord has the characteristic double 

 crescentic shape, approaches more and more the posterior surface 



