Posterior Approaches to the Medial Temporal Region are by the occipital interhemispheric and the supracerebellar transtentorial routes. A–C, Occipital interhemispheric approach. A, Right occipital pole has been retracted away from the falx and tentorium. Usually, there are no Bridging veins between the superior sagittal sinus and the occipital pole. The occipital lobe has been retracted to expose the falx, tentorium, and straight sinus. B, An incision has been made in the tentorium parallel to and 1 cm from the straight sinus. Opening the tentorium allows the medial edge of the tentorium to fall away from the lower surface of the parahippocampal gyrus and aids in exposing the posterior and middle parts of the medial temporal region and the adjacent quadrigeminal and ambient cisterns. C, Magnetic resonance imaging scan with image guidance showing that the exposure by the occipital transtentorial approach extends anteriorly to the posterior part of the posterior uncal segment and crural cistern. D–F, Right supracerebellar transtentorial approach. D, The cranial opening is centered toward the side of the temporal lobe to be exposed. The exposure extends from the transverse sinus to or near the foramen magnum to provide multiple working corridors and allow opening of cisterna magna and cerebrospinal fluid drainage to relax the cerebellum. E, The exposure is directed across the right paramedian part of the upper surface of the cerebellum. The arachnoid covering the quadrigeminal and ambient cisterns has been opened. The trochlear nerve, superior cerebellar arteries, and P3 segments of the posterior cerebral artery have been exposed. F, The right half of the tentorium has been divided to expose the middle and posterior parts of the medial temporal region and the ambient and the posterior part of the crural cistern. The parahippocampal gyrus and the P2P segment of the posterior cerebral artery are exposed in the ambient cistern and the P2A is exposed in the posterior part of the crural cistern. G, The middle and posterior parts of the parahippocampal gyrus and the adjacent part of the hippocampus have been removed. The lateral margin of the resection was directed through the collateral sulcus. The choroid plexus remains attached to the lower margin of the thalamus in the area beside the lateral geniculate body. H, Magnetic resonance imaging scan with image guidance showing the exposure extending along the medial temporal region and parahippocampal gyrus to the posterior part of the crural cistern. (Images courtesy of AL Rhoton, Jr.)