Left temporal lobe (superior view). The first transverse temporal gyrus (Heschl gyrus) divides the superior surface of the superior temporal gyrus within the Sylvian fissure into planum polare anteriorly and planum temporale posteriorly (the latter is formed by the middle and posterior transverse temporal gyri). The Heschl gyrus or primary auditory cortex runs obliquely, in a posteromedial direction, and points towards the atrium of the lateral ventricle. One can think of the medial temporal lobe as a "ladder" with the following "steps" going from medial to lateral: the parahippocampal gyrus, the dentate gyrus (which means "teeth-like," as it is shaped like a denture by the impressions of small transverse crossing vessels), the fimbria, and the hippocampus. The anterior parahippocampal gyrus forms a "hook" called uncus. The uncus has an anterior and posterior surface and a group of small gyri. The apex of the uncus projects medially and is in close proximity to the oculomotor nerve and midbrain. Posteriorly there are small gyri overlying the infolded head of the hippocampus (uncinate gyrus, band of Giacomini, and intralimbic gyrus). The semianular sulcus separates the ambient gyrus superiorly from the semilunar gyrus. The uncal recess separates the hippocampus from the amygdala. The collateral eminence is a protuberance in the wall of the temporal horn made by the collateral sulcus. (Image courtesy of AL Rhoton, Jr.)