Anteroinferior view of the brain with dissection of the temporal lobe exposing the amygdala. The basilar bifurcation is retracted with a dissector to demonstrate the thalamoperforating arteries originating along the superior surface of the right P1 segment and posterior surface of the left P1 segment, and traveling posteriorly toward the posterior perforated substance. The mamillary perforating branches arise along the middle third of the posterior communicating artery. 1, Thalamoperforating arteries; 2, posterior perforated substance; 3, P1 segment; 4, P2A segment; 5, oculomotor nerve; 6, posterior communicating artery; 7, mamillary body; 8, pituitary stalk; 9, optic chiasm; 10, amygdala; 11, limen insulae; 12, hippocampus head. (Image courtesy of E de Oliveira)