Basal View of Frontal Lobe. The superficial sulci and gyri have been removed. 1 = genu of the corpus callosum; 2 = cavity of the frontal horn; 3 = rostrum of the corpus callosum; 4 = posterior wall of the anterior limiting sulcus of the insula (anterior surface of the insula); 5 = head of the caudate nucleus; 6 = olfactory tract; 7 = temporal lobe; 8 = anterior perforated substance; 9 = MCA (M2 segment); 10 = anterior portion of the parahippocampal gyrus. (Image courtesy of AL Rhoton, Jr.)