THE MEDULLA OBLONGATA. 175 



2. The lateral tract is continuous with the lateral columns of the cord; its 

 fibers in passing upward take three directions viz., an external bundle 

 joins the restiform body, and passes into the cerebellum; an internal bundle 

 decussates at the median line and joins the opposite ventral pyramid; a 

 middle bundle ascends beneath the olivary body, behind the pons, to the 

 cerebrum, as the fasciculus teres. The olivary body of each side is an oval 

 mass, situated between the ventral pyramid and restiform body; it is com- 

 posed of white matter externally and gray matter internally, forming the 

 corpus dentatum. 



FIG. 24. VIEW OF CEREBELLUM IN SECTION, AND OF FOURTH VENTRICLE, WITH 



THE NEIGHBORING PARTS. (From Sappey.) 



i. Median groove fourth ventricle, ending below in the calamus scriptorius, with 

 the longitudinal eminences formed by the fasciculi teretes, one on each side. 2. 

 The same groove, at the place where the white streaks of the auditory nerve emerge 

 from it to cross the floor of the ventricle. 3. Inferior peduncle of the cerebellum, 

 formed by the restiform body. 4. Dorsal pyramid; above this is the calamus 

 scriptorius. 5, 5. Superior peduncle of cerebellum, or processes e cerebello ad testes. 

 6, 6. Fillet to the side of the crura cerebri. 7,7. Lateral grooves of the crura cere- 

 bri. 8. Corpora guadrigemina. (After Hirschfeld and Leveille.) 



3. The restiform body, continuous with the dorsal column of the cord, also 

 receives fibers from the lateral column. As the restiform bodies pass 

 upward they diverge and form a space (the fourth ventricle), the floor of 

 which is formed by gray matter, and then turn backward and enter the 

 cerebellum. 



4. The dorsal pyramid is a narrow white cord bordering the posterior median 

 fissure; it is continued upward, in connection with ihe fasciculus teres, to 

 the cerebrum. 



