Pig. 21. THE ARTERIAL SUPPLY AT THE BASE OF THE BRAIN (Circle of Wil- 

 lis). i, Olfactory nerve. 2, Optic nerve and chiasm. 3, Infundibulum torn off the 

 tuber cinereum. 4, Corpora albicantia. 5, Fourth nerve. 6, Fifth nerve. 7, The 

 sixth nerve. 8, Anterior cerebral, united by the anterior communicating. 9, Internal 

 carotid. 10, Posterior communicating, n, Third nerve. 12, Posterior cerebral artery. 

 13, Superior (anterior) cerebellar artery. 14, Basilar artery. 15, Inferior (posterior) 

 cerebellar artery. 



