STRUCTUBE OF THE MEDULLA OBLONGATA. 403 



tracts of which each half of the spinal cord is made up. The 

 columns are more prominent than those of the spinal cord, and 

 separated from each other by deeper grooves. The anterior, 

 continuous with the anterior columns of the cord, are called 

 the anterior pyramids ; the posterior, continuous with the pos- 

 terior columns of the cord, are called the restiform bodies ; and 



FIG. 143. 



FIG. 144. 



FIG. 143. View of the anterior surface of the pons varolii, and medulla oblongata. 

 a, a, anterior pyramids, b, their decussation ; c, c, olivary bodies ; d, d, restiform 

 bodies ; e, arciform fibres ; /, fibres described by Solly as passing from the anterior 

 column of the cord to the cerebellum ; g, anterior column of the spinal cord ; h, 

 lateral column ; p, pons varolii ; i, its upper fibres ; 5, 5, roots of the fifth pair of 

 nerves. 



FIG. 144. View of the posterior surface of the pons varolii, corpora quadrigemina, 

 and medulla oblongata. The peduncles of the cerebellum are cut short at the side. 

 a, a, the upper pair of corpora quadrigemina ; b, b, the lower ;/,/, superior peduncles 

 of the cerebellum ; c, eminence connected with the nucleus of the hypoglossal 

 nerve ; e, that of the glosso-pharyngeal nerve ; i, that' of the vagus nerve ; d, d, resti- 

 form bodies ; p, p, posterior pyramids ; v, ?>, groove in the middle of the fourth ven- 

 tricle, ending below in the calamus scriptorius; 7, 7, roots of the auditory nerves. 



the lateral, continuous with the lateral columns of the cord, are 

 named simply from their position. On the fibres of the lateral 

 column of each side, near its upper part, is a small oval mass, 

 containing gray matter, and named the olivary body ; and at 

 the posterior part of the restiform column, immediately on 

 each side of the posterior median groove, a small tract is 

 marked off by a slight groove from the remainder of the resti- 



