Topographic anatomy of the insular region

abject. The insula is one of the paralimbic structures and constitutes the invaginated portion of the cerebral cortex, forming the base of the sylvian fissure. The authors provide a detailed anatomical study of the insular re gion to assist in the process of conceptualizing a reliable surgical approa ch to allow for a successful course of surgery. Methods. The topographic anatomy of the insular region was studied in 25 fo rmalin-fixed brain specimens (50 hemispheres). The periinsular sulci (anter ior, superior, and inferior) define the limits of the frontoorbital, fronto parietal, and temporal opercula, respectively. The opercula cover and enclo se the insula. The limen insula is located in the depths of the sylvian fis sure and constitutes the anterobasal portion of the insula. A central insul ar sulcus divides the insula into two portions, the anterior insula (larger ) and rbe posterior insula (smaller). The anterior insula is composed of th ree principal short insular gyri (anterior, middle, and posterior) as well as the accessory and transverse insular gyri. All five gyri converge at the insular apex, which represents the most superficial aspect of the insula. The posterior insula is composed of the anterior and posterior long insular gyri and the postcentral insular sulcus, which separates them. The anterio r insula was found to be connected exclusively to the frontal lobe, whereas the posterior insula was connected to both the parietal and temporal lobes . Opercular gyri and sulci were observed to interdigitate within the opercu la and to interdigitate the gyri and sulci of the insula. Using the fiber d issection technique, various unique anatomical features and relationships o f the insula were determined. Conclusions. The topographic anatomy of the insular region is described in this article, and a practical terminology for gyral and sulcal patterns of surgical significance is presented. This study clarifies and supplements th e information presently available to help develop a more coherent surgical concept.