STRUCTURE OF THE MEDULLA OBLONGATA. 511 



columns, and partly in fasciculi traversing the central grey 

 matter. The medulla oblongata is larger than any part of 

 the spinal cord. Its columns are pyriform, enlarging as 

 they proceed towards the brain, and are continuous with 

 those of the spinal cord. 



Each half of the medulla, therefore, may be divided into 

 three columns or tracts of fibres, continuous with the three 

 Fig. 136.* Fig. 137-t 



* Fig. 136. 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 y anterior column of the spinal cord ; A, lateral column ; p, pons varolii 

 ', its upper fibres ; 5,5, roots of the fifth pair of nerves. 



f Fig. 137. 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 ; *, that of the vagus nerve ; d, d, restiform 

 bodies ; p, p, posterior pyramids ; v, v, groove in the middle of the 

 fourth ventricle, ending below in the calamus scriptorius ; 7, 7, roots of 

 the auditory nerves. 



