THE CEREBRAL CIRCULATION, ARTERIES. 15 



ary of the circle. The posterior cerebral arteries bound the 

 circle behind, and so complete it (Fig. 10). The large distal 

 branches of the arteries which are connected with the arterial 

 circle are distributed chiefly to the cortex and medulla of the 

 hemispheres; while the small proximal branches supply the 



Fig. 9. Arterial circle and its branches on the base of the brain. 

 (After Morris's Anatomy.} 



a. Anterior cerebral artery, b. Middle cerebral artery, c. Internal carotid artery, d. Pos- 

 terp-median ganglionic. e. Posterior cerebral artery, f. Superior cerebellar artery, g. An- 

 terior inferior cerebellar artery, h. Vertebral artery, i. Posterior inferior cerebellar artery. 

 j. Anterior communicating artery, k. Antero-lateral ganglionic. 1. Anterior chorioid. 

 m. Posterior communicating artery, n. Posterior chorioid. o. Basilar artery, p. Hemis- 

 phere of cerebellum cut away. q. Anterior spinal artery. 



ganglia and the inter-brain. The former belong to the cortical 

 system (Ai), the latter to the ganglionic system (A2). 



Al. The Cortical System of Arteries. The cortical arterial 

 system comprises the distal portions of the anterior, middle and 

 posterior cerebral and the chorioidal arteries. The branches of 



