MEDULLA OBLONGATA. 



183 



the posterior is prolonged, behind the pons, into the floor of the fourth 

 ventricle. 



Each half of the medulla is constituted of pieces continuous with those 

 of the spinal cord (fig. 54); and slight grooves indicative of these divi- 

 sions are to be seen on the surface. Thus at the middle line in front is 

 the anterior pyramid ( l ) corresponding with the anterior column of the 

 cord ; at the middle line behind is the small posterior pyramid (*) con- 

 tinuous with the posterior median column. On the side is the larger pro- 

 jecting restiform body ( 3 ), joining below the posterior column of the cord; 

 and between this and the anterior pyramid is the lateral tract ( 2 ), with an 

 oval projecting body (corpus olivare) ( 5 ) on the exterior, which blends 

 below with the lateral column. 



Fig. 55. 



ANTERIOR VIEW OF THE MEDULLA OBLONGATA 

 AND PONS. 



1. Anterior pyramid. 



2. Lateral tract. 



3. Restiform body. 

 f>. Corpus olivare. 

 6. The decussation. 



HINDER VIEW OF THE MEDULLA OBLOXGAT. 



1. Floor of the fourth ventricle. 



2. Einiuentia teres. 



3. Restiform hody. 



4. Posterior pyramid. 



The anterior pyramid (fig. 54, l ) is the most internal eminence and 

 receives its name from its position and form. Situate on the side of 

 the median fissure, it is internal to the olivary body, from which it is sepa- 

 rated by a slight groove. Enlarging as it ascends, this body enters the 

 pons, but before disappearing beneath the transverse fibres, it is somewhat 

 constricted and rounded. 



Lateral tract and olivary body. The lateral tract (funiculus lateralis) 

 ( 2 ) fills the interval between the anterior pyramid and the restiform body. 

 Its surface width is not the same throughout : opposite the lower part of 

 the medulla oblongata it measures as much as the pyramid ; but near the 

 pons it is concealed by the olivary body, so that it is seen only in the 

 narrow interval between the outer side of the corpus olivare and the resti- 

 form body. 



The olivary body (corpus olivare) ( 5 ) is an oval projection, about half 



