A, The scalp incision is shown in the inset and the left frontotemporal bone flap has been outlined. A cuff of temporalis fascia is left along the superior temporal line for closure. B, The temporal lobe has been elevated to expose the anterior and posterior segment of the uncus. The anterior segmentcontains most of the amygdala and faces the internal carotid artery. The posterior segment contains the head of the hippocampus and faces the posterior cerebral artery and cerebral peduncle. The uncal apex is located lateral to the oculomotor nerve and posterior communicating artery. C, The temporal horn has been opened by incising through the collateral sulcus, and the inferior temporal and occipitotemporal gyri lateral to the collateral sulcus have been removed. The medial disconnection is performed by opening the choroidal fissure between the choroid plexus and fimbria. D, The taenia fimbria, which attaches the choroid plexus to the fimbria, has been divided and the choroid plexus elevated with the thalamus. Opening the choroidal fissure exposes the branches of the anterior choroidal artery entering the choroid plexus and the ambient cistern. The choroid plexus remains attached to the thalamus. E, The hippocampus and adjacent parahippocampal gyrus have been removed. The posterior cerebral artery courses through the crural and ambient cistern on the medial side of the uncus and parahippocampal gyrus. Some of the amygdala in the upper margin of the anterior uncal segment was not removed to avoid dissection and damage along the optic tract. The lateral geniculate body is exposed medial to the choroidal fissure. The anterior and lateral posterior choroidal arteries enter the choroid plexus by passing through the choroidal fissure. F, In this dissection, the posterior cerebral artery and basal vein were removed to expose the roof of the temporal horn and the lateral geniculate body. The inferior ventricular vein drains some of the central core of the hemisphere and passes medially across the roof of the temporal horn formed by the tapetum to the reach the basal vein. (Images courtesy of AL Rhoton, Jr.)