Medial Perspective of the Right Uncus. A, Medial side of the right uncus. The AChA passes above the semiannular sulcus and uncinate gyrus to reach the lower end of the choroidal fissure, where it enters the temporal horn. The PCA courses medial to the uncal sulcus, which divides the posterior segment of the uncus into upper and lower parts. B, The PCA has been removed to expose the uncal sulcus. The AChA ascends along the anterior segment of the uncus to reach the area above the uncal apex, where it turns laterally above the posterior uncal segment and passes through the inferior choroidal point at the lower end of the choroidal fissure located just behind the posterior uncal segment and the head of the hippocampus to enter the temporal horn. C, The AChA has been removed to expose the anterior segment of the MTR, which is supplied by branches of the ICA, AChA, and MCA and PCA. D, Medial view of the anterior segment of the right MTR in another specimen. This cross section extends through the midline of the sella. The view is directed laterally over the top of the sella to the medial aspect of the ICA, the uncus, and the origin of the anterior choroidal and anterior, MCA, and PCA. The AChA passes around the uncus to reach the lower end of the choroidal fissure. The basal vein hides the uncal sulcus. The deep middle cerebral and inferior ventricular veins empty into the basal vein. (Images courtesy of AL Rhoton, Jr.)