Vascular Relationships of the Anterior Segment of the Medial Temporal Region. E, Lower surface of another MTR. The entorhinal area is irrigated anteriorly by an uncoparahippocampal artery that arises from the M1, and posteriorly by an anterior parahippocampal artery originating from the AITA. F, Lower surface of another MTR. An anterior hippocampal artery arises from the AITA and enters the uncal sulcus to irrigate the extraventricular hippocampal head. (Images courtesy of AL Rhoton, Jr.)