Figure 5: (a) Circle of Willis showing adult type of posterior circulation on right side and Persistent fetal type-partial on left side. PComA: Posterior communicating artery, PCA: Posterior cerebral artery, P1: Precommunicating part of posterior cerebral artery, and ICA: Internal carotid artery. (b) Transitional type on right side. Note Persistent fetal type-partial on left side. PComA: Posterior communicating artery, PCA: Posterior cerebral artery, P1: Precommunicating part of posterior cerebral artery, ICA: Internal carotid artery. (c) Persistent fetal type- full on left side. Note adult type on right side. PComA: Posterior communicating artery, PCA: Posterior cerebral artery, P1: Precommunicating part of posterior cerebral artery, ICA: Internal carotid artery