Drawings of the Lateral View of the Left Opercular and Insular Regions. A, The opercular and insular areas are labeled. B, Distances between the points in this figure are listed in Table 1. Points A, C, and E were located at the apices of the partes orbitalis, triangularis, and opercularis, respectively. The measurements from A to B, C to D, and E to F are the depths from the cortical surface along the opercular lips of the inferior frontal gyrus to the anterior and superior limiting sulci. Point I was located at the proximal end of the Heschl gyrus on the cortical surface of the superior temporal gyrus, and Point H was situated at the posterior end of the Heschl gyrus (the junction of the superior and inferior limiting sulci). The measurement from G to H was the distance between the supramarginal gyrus and the posterior end of the insula. Point J was located at the insular apex, the highest or the most prominent laterally projecting point on the insular convexity. Point K was situated at the origin of the most lateral LSA from the MCA. C, Enlarged view of the insula. The distances between the points in this figure are featured in Table 2. The points are located as follows: A, inferior end of central insular sulcus; B, midpoint of anterior limiting sulcus; C, inferior limit of limen insulae; D and F, junctions of anterior and superior, and superior and inferior limiting sulci, respectively; E and H, midpoints of superior and inferior limiting sulci, respectively; and G, apex of insula. (Images courtesy of AL Rhoton, Jr.)