The term precentral gyrus refers to the convolution of cerebral cortex immediately rostral to the central sulcus in human ( Carpenter-1983 ) and macaque ( Martin-2000 ). Defined by dissection, it is located at the caudal extreme of the frontal lobe. In the human it is variably bounded rostrally by the superior precentral sulcus, the intermediate precentral sulcus and the inferior precentral sulcus; it is bounded on the mesial surface of the hemisphere by the cingulate sulcus. Ventrolaterally it is bounded by the lateral fissure and forms a lip over the insula known as the precentral operculum. The boundaries in the macaque are similar except that the rostral border is partially defined by the spur of the arcuate sulcus and the inferior ramus of the arcuate sulcus. It occupies a much larger proportion of the frontal lobe in the macaque than in the human. Equivalent structures are not found in the smooth cerebral cortex of the rat or mouse.