FIG 7. A and B, Sagittal T2-weighted MR images of the left hemisphere in a 34-year-old woman show the opercular-insular relationship. The union of the pars opercularis (op) of the inferior frontal gyrus with the inferior end of the precentral gyrus (4) forms a very bulky "pseudomass" (Ø) that invaginates into the convexity surface of the anterior lobule, depresses the insular surface at the MSG, and splays the ASG (a) apart from the PSG (p). (See also Figs 1 and 3.)