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Three stages in the development of the insula and the insular opercula.

Development of the Insula

Three stages in the development of the insula and the insular opercula.

Diagram to illustrate the development of the opercula which cover the insula. A, Sylian fossa before opercula begin to form. B, Fronto-paretal and temporal opercula wells advances. C, All the four opercula developed but not in opposition. Labels: F.P., fronto-parietal operculum; T, temporal operculum; F.R., frontal wall of fossa; O.R., orbital wall of fossa; F., frontal operculum; O, orbital operculum; s2, anterior horizontal limb of Sylvian fissure; s3, ascending limb; s4, posterior horizontal limb.

Development of the Opercula

Diagram to illustrate the development of the opercula which cover the insula. A, Sylian fossa before…