Medial Perspective of the Right Uncus. E and F, The orientation of E to I is the same as shown in E. E, Inferior view of the anterior segment of the left MTR. The semilunar gyrus has been retracted to expose the branches of the AChA. Interestingly, 2 anterior uncal arteries arise from the first third of the AChA and irrigate the semilunar gyrus. The inferior lip of the posterior uncal segment, formed by the parahippocampal gyrus, has been removed to expose the extraventricular hippocampal head. A posterior uncal artery from the AChA penetrates the uncal sulcus and irrigates the extraventricular hippocampal head. An anterior hippocampal-parahippocampal artery arising from the anteroinferior temporal branch of the PCA gives rise to an anterior hippocampal branch that enters the uncal sulcus to vascularize the extraventricular hippocampal head, and an anterior parahippocampal branch that irrigates the entorhinal area. In this specimen, the anterior parahippocampal branch has been sectioned to expose the anterior hippocampal artery that anastomoses with the uncohippocampal branch of the AChA (green arrow). F, Basal surface of another temporal lobe. An anterior uncal artery arises from the M1, loops forward below the M1 and then back (curved arrow), irrigates the anterior part of the anterior segment of the uncus (ambient gyrus) and the anterior part of the entorhinal area (parahippocampal gyrus), and anastomoses (green arrows) with the anterior parahippocampal branches of the AITA at the rhinal sulcus. As in E, anterior and posterior uncal arteries arise from the AChA. The anterior inferior temporal branch of the PCA, crosses the anterior parahippocampal gyrus from medial to lateral to enter the rhinal sulcus, and gives off 3 anterior parahippocampal arteries that irrigate the entorhinal area. G, Detail of same specimen as in part F. The carotid artery has been retracted medially. An anterior uncal artery arises from the M1 ventral to a lenticulostriate artery. The origin of the AChA and its anterior uncal branch are exposed. H, The basal vein and the PCA have been retracted medially to expose the branches of the AChA. An anterior uncal artery arises from the first third of the AChA to irrigate the semilunar gyrus. Remarkably, in this case a perforating artery to the optic tract arises in common with the anterior uncal artery. A posterior uncal artery arises from the middle third of the AChA, descends parallel to the band of Giacomini toward the uncal sulcus, and distributes along the posterior segment of the uncus. I, The parahippocampal gyrus and hippocampus have been removed to expose the choroid plexus below the roof of the temporal horn. The AChA enters the temporal horn and choroid plexus at the inferior choroidal point. Three neural branches arise from the plexal segment of the AChA (green arrows). They perforate the lateral geniculate body and pulvinar. (Images courtesy of AL Rhoton, Jr.)