Medial Temporal Lobe. Fiber dissection of the left mediobasal cerebral surface. The cortical gray matter of the isthmus, and lingual, parahippocampal, and occipitotemporal gyri, have been removed. The uncus is divided into an anterior segment, which contains the amygdala, and a posterior segment, which contains the hippocampal head. The fibers of the cingulum traveling inside the isthmus and parahippocampal gyrus, and the fibers of the subiculum, have been removed to expose the most external cortical layer of the hippocampus. The fasciolar gyrus, and its continuation, the subsplenial gyrus, form part of the hippocampal tail at the subsplenial level. The subsplenial gyrus surrounds the splenium and is continued by the indusium griseum above the splenium. The indusium griseum runs along the superior surface of the corpus callosum to reach the subcallosal area. The lateral longitudinal stria courses on the indusium griseum. The fimbria passes posteriorly to become the crus of the fornix. The crus wraps around the posterior surface of the pulvinar of the thalamus and arches superomedially toward the lower surface of the splenium of the corpus callosum. At the junction of the atrium and the body of the lateral ventricle, the paired crura meet to form the body of fornix, which runs forward along the superomedial border of the thalami in the medial wall of the body of the lateral ventricle. The body of fornix splits into two columns at the anterior margin of the openings of the foramen of Monro into the lateral ventricles. The column of fornix ends in the mammillary body. Removal of the gray matter of the lingual and occipitotemporal gyri exposes the optic radiations coursing on the lateral wall and roof of the temporal horn and adjacent fibers of the inferior longitudinal fasciculus. (Image courtesy of E de Oliveira)