The term triangular part of the inferior frontal gyrus (IFGtr) refers to one of three parts of the frontal operculum of the inferior frontal gyrus (IFG), which overlies the insula (INS).. Its boundary with the INS is the superior limiting sulcus (sls) ( Ture-1999 ). Identified by dissection, it is the middle part. The others are the orbital part of the inferior frontal gyrus (IFGor) and the opercular part of the inferior frontal gyrus (IFGop). It is found in the human ( Carpenter-1983 ), but not in the macaque ( Martin-2000 Paxinos-2009a ), rat or mouse ( NeuroNames ). Updated 23 Aug 2024.