The term frontal operculum (OPRfr) refers to the part of the frontal lobe (FLB) that overlies the rostrodorsal portion of the insula (INS) in the human ( Ture-1999 ) and macaque ( Mesulam-1985 ). Identified by dissection, it is separated from the INS deep in the lateral fissure (ltf) by the anterior two-thirds of the superior limiting sulcus (slms). In the human it is subdivided into the orbital part of the inferior frontal gyrus (INFor), the triangular part of the inferior frontal gyrus (INFtr) and the opercular part of the inferior frontal gyrus (INFop) ( Mai-2004; Schiebler-1999 ). In the macaque, it includes part of ventrolateral precentral gyrus (PRG) ( Martin-2000 ) and is not subdivided ( Mesulam-1985 ). Functionally, the most rostral part of the OPRfr in the macaque is gustatory cortex ( Mesulam-1985 ). The OPRfr is is not present in the smooth cerebral cortex (CTX) of the rat and mouse ( Neuronames ). Upddated 29 Aug 2024.