Central Core of the Left Hemisphere. 1 = genu of the corpus callosum; 2 = anterior limiting sulcus of the insula; 3 = frontal horn; 4 = head of the caudate nucleus; 5 = foramen of Monro; 6 = lentiform nucleus; 7 = internal capsule; 8 = thalamus; 9 = inferior limiting sulcus of the insula, retroinsular region; 10 = fornix; 11 = atrium; 12 = splenium of the corpus callosum; 13 = tapetum of the corpus callosum. (Image courtesy of AL Rhoton, Jr.)