The term primary intermediate sulcus refers to the more rostral of two sulci that branch ventrally from the intraparietal sulcus in the parietal lobe of the human. It marks part of the boundary between the supramarginal gyrus and the angular gyrus ( Duvernoy-1992 ). The other, located more caudally, is the secondary intermediate sulcus ( Ono-1990 ). It is not found in the macaque or in the smooth cerebral cortex of the rat or mouse ( NeuroNames ).