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| Circle of Willis Cerebral Arterial Circle | Willis' | Circle | Arterial Circle, Cerebral | Circle, Willis' | | Willis Circle A polygonal anastomosis at the base of the brain formed by the internal carotid (CAROTID ARTERY, INTERNAL), proximal parts of the anterior, middle, and posterior cerebral arteries (ANTERIOR CEREBRAL ARTERY, MIDDLE CEREBRAL ARTERY, POSTERIOR CEREBRAL ARTERY), the anterior communicating artery and the posterior communicating arteries. |