THE CIRCULATION OF THE RHOMBEXCEPHALON. 27 



bellar artery supplies the superior medullary velum and the 

 brachia conjunctiva cerebelli. The branches enter the median 

 raphe, also the substance of the pons elsewhere, especially along 

 the nerve roots, and run at right angles to the surface into it. 

 The deep veins of the pons run forward and form a plexus on its 

 surface which, according to Cunningham, is drained by a superior 

 efferent into the basilar vein and by an inferior efferent into the 

 cerebellar veins or the superior petrosal sinus. There are no 



Fig. 13. Arteries of the medulla oblongata. (Modified from Gordinier after Duret.) 



a. spin. post. Posterior spinal artery, a.vertebr. Vertebral artery, a.spin.ant. Anterior spinal 



artery. 



lymphatic vessels in the pons; but, as elsewhere in the central 

 nervous system, there are lymph spaces about the blood-vessels. 



B3. The blood supply of the cerebellum is furnished by 

 three pairs of arteries (Fig. 9). The superior cerebellar, from 

 the basilar, supplies all the superior surface except a narrow zone 

 at the posterior border; the anterior inferior cerebellar, also from 

 the basilar, and the posterior inferior cerebellar, from the verte- 

 bral, supply the inferior surface and the posterior part of the 

 superior surface. 



The Superior Cerebellar Artery. (A. cerebelli superior}. 

 Rising from the basilar just behind the posterior cerebral, from 



