View of the medial surface of the left hemisphere. The parahippocampal gyrus was dissected and an axial section 5 mm inferior to the anterior commissure was done. The posterior cerebral artery is retracted inferiorly with a dissector. The hippocampal artery originates from the common temporal artery and travels laterally along the fimbriodentate sulcus. Posterior to the hippocampal artery is the posterolateral choroidal artery, which originates from the P2P segment, and travels laterally going through the choroidal fissure to enter the temporal horn 1 cm posterior to the choroid point. 1, P2A segment; 2, P2P segment; 3, hippocampal artery; 4, posterolateral choroidal artery; 5, dentate gyrus; 6, fimbria; 7, choroidal fissure; 8, inferior choroidal point. (Image courtesy of E de Oliveira)