Anatomical Variations of the Circulus Arteriosus in Cadaveric Human Brains

Figure 2

Classical circle of Willis. (1) ACoA, anterior communicating artery, (2) A1, precommunicating segment of anterior cerebral artery (ACA), (3) PoCA, posterior communicating artery, (4) P1, precommunicating segment of posterior cerebral artery (PCA), (5) BA, Basilar artery, (6) P2, postcommunicating segment of posterior cerebral artery (PCA), (7) ICA, internal carotid artery, (8) MCA, middle cerebral artery, (9) A2, postcommunicating segment of ACA, and (10) SCA, superior cerebellar artery.

(a)

(b)