246 



THE RHOMBENCEPHALON. 



hypothalamic region of the opposite side. They end chiefly 

 in the red nuclei, which their fibers surround. Near the corpora 

 quadrigemina each brachium conjunctivum is obliquely crossed 

 by the lateral fillet in its course to the inferior quadrigeminal 

 colliculus. 



The superior medullary velum (valve of Vieussens, Figs. 

 86, 87 and 92), is a trapezoidal sheet of white substance, wider 

 where it fuses with the corpus medullare of the cerebellum than 

 at the mesencephalic end. It forms the floor of the groove between 

 the brachia conjunctiva cerebelli and the superior half of the 



Fig. 78. Dissection of rhombencephalon to show brachium conjunctivum, brachium 

 pontis and corpus restiforme. (Gordinier, Sappey after Hirschfeld and Leveillc.} 



On left side the cerebellar brachia and restiform body have been cut short; the right 

 hemisphere is cut obliquely to show connection with brachium conjunctivum and corpus 

 restiforme. i. Median groove of fourth ventricle. 2. Medullary striae. 3. Restiform body. 

 4. Clava in fuhiculus gracilis. 5,5. Brachium conjunctivum. 6. Lateral fillet. 7,7. Lateral 

 sulcus of mid-brain. 8. Corpora quadrigemina. 



roof of the fourth ventricle. Its lateral borders fuse with and 

 unite the brachia conjunctiva, hence their name. In the median 

 line its posterior surface presents a slight ridge, the fr&nulum 

 veil, from either side of which emerges the trochlear nerve. 



The corpora restiformia (inferior peduncles of the cerebel- 

 lum) issue from the cerebellum betwe.en the brachium conjunc- 

 tivum and the brachium pontis (Figs. 78 and 86). They first run 

 forward to the posterior surface of the pons, near the inferior 

 border; and then, bending downward and backward (a flexion 



