THE CEREBELLUM. 



247 



of more than 90 degrees), they converge in the posterior areas 

 of the medulla toward the calamus scriptorius. They help to 

 form the floor and to bound laterally the inferior half of the fourth 

 ventricle. 



The brachia pontis (middle peduncles) join the cerebellum 

 to the lateral borders of the pons (Figs. 78, 85 and 91). They 

 are continuous with the transverse fibers in the ventral area of 



Fig. 79. Median section of cerebellum, pons and medulla. (Original.) 



a. Predeclivil sulcus. b. Arbor vitae. c. Declive monticuli. d. Postdeclivil sulcus. e. 

 Folium vermis. f. Horizontal sulcus. g. Tuber vermis. h. Postpyramidal sulcus. i. 

 Pyramid, j. Prepyramidal sulcus. k. Uvula. 1. Culmen monticuli. m. Postcentral sulcus. 

 n. Central lobule, o. Inferior colliculus of corp. quad. p. Cerebral aqueduct, q. Precentral 

 sulcus. r. Superior medullary velum, s. Lingula. t. Medial longitudinal bundle, u. 

 Fastigium. v. Inferior medullary velum, w. Nodule, x. Postnodular sulcus. 



the pons. The brachia pontis in the anterior cerebellar notch 

 are placed external to the brachia conjunctiva and the restiform 

 bodies, and are opposite the widest part of the fourth ventricle. 

 Horizontal Sulcus of Cerebellum (Figs. 76, 79 and 80). 

 The cerebellum has one great sulcus which divides it into upper 

 and lower surface. The sulcus horizontalis cerebelli is irregularly 

 circular in shape; anteriorly its lips are separated by the prolonga- 

 tion of the medullary body from which the sulcus runs backward, 



