Surgical Anatomy of the insula

The insula was for a long time considered as one of the most challenging areas of the brain. This is mainly related to its location, deep and medial to the frontoparietal, temporal, and fronto-orbital opercula. Another difficulty is the content of the lateral fossa, located between the insula and the opercula, which contains the trunks, stem, arteries, and cortical branches of the insular (M2) and opercular (M3) segments of the middle cerebral artery (MCA). Finally, the insula is surrounded by several white matter tracts and cortical structures having important functional roles, especially for language in the dominant hemisphere; the insula is indeed located between a dorsal phonological stream, centered by the arcuate fasciculus and lateral to the posterior insula, and a ventral semantic system, medial to the ventral aspect of the insula and centered by the inferior fronto-occipital fasciculus (IFOF). This chapter reviews some of these surgically relevant anatomical relationships.