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a long, deep sagittal fissure on the undersurface of the temporal lobe, marking the border between the fusiform gyrus laterally and the hippocampal and lingual gyri medially; the great depth of the collateral sulcus results in a bulging of the floor of the occipital and temporal horn of the lateral ventricle, the collateral eminence.
A groove running longitudinally on the inferior (under) surface of the temporal lobe of the brain. It is parallel to the collateral sulcus, from which it is separated by the medial occipitotemporal gyrus.
See also: sulcus