The term precentral sulcus refers to a composite superficial feature of the frontal lobe identified by dissection in the human. It is a discontinuous sulcus that consists of 2 to 4 segments located rostral and parallel to the central sulcus. The most common segments are the superior precentral sulcus and the inferior precentral sulcus. They separate the precentral gyrus from the superior frontal gyrus and the inferior frontal gyrus respectively, and they occur in most brains. Less common segments are the intermediate precentral sulcus, which appears in up to 20% of brains and separates the precentral gyrus from the middle frontal gyrus, and the marginal precentral sulcus located between the upper end of the superior segment and the longitudinal fissure ( Ono-1990 ). The macaque has a superior precentral sulcus and an anterior subcentral sulcus. Both are short horizontal grooves embedded in the precentral gyrus ( Martin-2000 ). Neither is clearly homologous to a segment of the precentral sulcus of the human. (See arcuate sulcus of the macaque.) Equivalent features are not found in the smooth cerebral cortex of the rat or mouse ( NeuroNames ).