Anatomical Studies of the Circle of Willis in Normal Brain

Introduction The present study was undertaken in order to determine the anatomical structures of the circle of Willis,27with the purpose of learning its normal configuration, the frequency of deficient or incomplete circles, and, if possible, how these findings can be correlated with the clinical problems of vascular disease, such as infarcts, aneurysms, and vascular anomalies. There are many problems in vascular disease of the brain which make desirable an intimate knowledge of variants in the anatomy of the circle of Willis. The state of the circle becomes important in determining the adequacy of the brain circulation in operations for cerebral aneurysm and in ligation of the carotid artery. The possibility of bypassing or shunting effects in occlusion of one of the cerebral vessels and the adequacy of recovery or lack of recovery after vascular occlusion might be explained in part by variations in the anatomy of the circle