The term frontal operculum (Ono) refers to an alternate definition of the frontal operculum in the human. It is the same as the standard definition in that it includes two structures that overlie the insula: the orbital part of the inferior frontal gyrus and the triangular part of the inferior frontal gyrus; but it differs in that it excludes the opercular part of the inferior frontal gyrus and the precentral operculum ( Ono-1990 ).