View of the medial surface of the left hemisphere. The brainstem was dissected preserving the optic tract and the lateral geniculate body. The internal carotid artery and the proximal cisternal segment of the anterior choroidal artery borders the anterior segment of the uncus, whereas the P2A segment borders the inferior posteromedial surface of the posterior segment of the uncus. 1, Posterior communicating artery; 2, P1 segment; 3, P2A segment; 4, common temporal artery; 5, P2P segment; 6, P3 segment; 7, calcarine artery; 8, parieto-occipital artery; 9, anterior choroidal artery; 10, thalamogeniculate artery; 11, posteromedial choroid artery; 12, optic nerve; 13, chiasm; 14, optic tract; 15, lateral geniculate body; 16, pulvinar; 17, subthalamic nuclei. (Image courtesy of E de Oliveira)