288 THE RHOMBENCEPHALON. 



thalamic tract, which runs up the posterior lateral groove. At 

 the junction of the medulla with the spinal cord the cerebello- 

 spinal fasciculus (direct cerebellar tract) passes from the lateral 

 to the posterior surface. The anterior external arcuate fibers, 

 running from the anterior surface backward to the restiform body, 

 may be so numerous as to conceal the lateral column and lower 

 part of the olive. 



The posterior surface (fades posterior] of the medulla com- 

 prises all the surface inclosed between the diverging posterior 

 lateral sulci (Fig. 86). It embraces the surfaces of the two pos- 

 terior areas of the medulla. 



Inferiorly, it is divided into lateral halves by the posterior 

 median fissure, and presents four bundles of fibers in each half 

 (Figs. 91, 94 and 96). From the fissure outward they are as 

 follows: The funiculus gracilis, funiculus cuneatus, tractus 

 spinalis n. trigemini, and the cerebello-spinal fasciculus. The fun- 

 iculus gracilis (Fig. 96) is a continuation of the medial tract of 

 the posterior column of the spinal cord, and the funiculus cune- 

 atus is in direct continuity with the lateral tract in the same column 

 of the cord. These two bundles leave the surface and end in the 

 nuclei of these columns in the medulla. The spinal tract of the 

 trigeminal nerve is here situated on the surface; its fibers end in 

 the under-lying gelatinous substance. The fasciculus cerebello- 

 spinalis (direct cerebellar tract) is continued up from the lateral 

 column of the spinal cord. Remaining on the surface it runs up 

 to the cerebellum through the restiform body. 



Superiorly, the posterior surface, on either side, is formed by a 

 large rounded band of fibers, the restiform body (Figs. 91 and 96). 

 The restiform body (corpus resli forme) is continued upward to 

 the pons and then bends backward into the corpus medullare of 

 the cerebellum in connection with which it has already been 

 studied. Of the superficial fibers in the medulla, the cerebello- 

 spinal fasciculus, and the anterior and posterior external arcuate 

 fibers are continued into the restiform body; and, as we have 

 already learned, the restiform body contains, in addition to the 

 above three tracts, the tract from the lateral nucleus and the cere- 

 bello-olivary tract. A single layer of flattened epithelial cells 



