fig 4.

Schematic drawing of an axial cut through the midbrain. The AChA (4) originates from the internal carotid artery (2), runs toward the medial aspect of the uncus (12), and then curves laterally along the medial aspect of the temporal lobe through the ambient cistern to the choroidal fissure (13). The uncal artery on the left has a common origin with the AChA. 1, optic nerve; 2, internal carotid artery; 3, PComA; 4, AChA; 5, uncal artery; 6, oculomotor nerve; 7, posterior cerebral artery; 8, tip of the basilar artery; 9, mesencephalon; 10, aqueduct of Sylvius; 11, cerebellum; 12, uncus of the temporal lobe; 13, choroidal fissure