Insular Perfusion Pattern. A, Photograph with superimposed shading to show the arterial supply to the insula. Different portions of the insula were exclusively supplied by the superior or inferior trunk of the MCA, with little overlap. The territory supplied exclusively by the superior trunk of the MCA is shaded red, and the territory supplied exclusively by the inferior trunk is shaded green. Areas receiving a contribution from the early branches are stippled. More specifically, the anterior, middle, and posterior short gyri; the anterior limiting sulcus; the short sulci; and the insular apex were exclusively supplied by the superior trunk of the MCA (red area), with variable contribution from the early branches to the anterior limiting sulcus (stippled area). In contrast to other portions of the insula, the central insular sulcus and anterior long gyrus were supplied by either the superior or the inferior trunk with approximately equal frequency and are referred to as the mixed zone (brown area). The inferior trunk of the MCA supplied the posterior long gyrus, inferior limiting sulcus, and limen area (green area). The inferior limiting sulcus received branches from the inferior trunk in approximately 90% of the cases and from the early branches (stippled area) in more than half of the hemispheres. The limen area received a contribution from the inferior trunk in approximately 90% of the hemispheres and from the early branches in approximately half of the cases (stippled area). B, Diagram of the most common cortical artery contributions to the supply of the insular gyri and sulci. Almost all of the 12 cortical arteries arising from the MCA, with the exception of the temporopolar artery, contributed to the insular supply (see Table 4). Some cortical branches of the MCA arose from a common stem artery that produced two or more cortical arteries. The insular area supplied by the orbitofrontal, prefrontal, and precentral arteries is shaded red; the area supplied by the central and anterior and posterior parietal arteries is shaded yellow; and the area supplied by the angular, temporooccipital, and posterior temporal arteries is shaded orange. The percentages of gyri and sulci in 43 hemispheres supplied by each cortical branch are shown for each specific insular area. The anterior limiting sulcus (oblique lines in red area) received its supply from the orbitofrontal artery in most of the hemispheres. The most consistent areas of supply included the anterior (transverse lines in red area) and middle (vertical lines in red area) short gyri, which were supplied by the prefrontal and precentral arteries in the majority of the hemispheres, respectively. The posterior short gyrus (transverse lines in yellow area) was supplied most frequently by the central artery. The central insular sulcus received perforating arteries from the central artery and the anterior parietal artery in almost half of the hemispheres. The anterior long gyrus (vertical lines in yellow area) was most commonly supplied by the anterior and posterior parietal arteries. The posterior long gyrus (transverse lines in orange area) and the inferior limiting sulcus (vertical lines in orange area) were exclusively supplied by three arteries: temporooccipital, angular, and posterior temporal arteries. The limen insulae (green area) was supplied predominantly by the initial portion of the inferior trunk proximal to the origin of the first cortical artery. The middle temporal artery, arising from an early temporal branch, sent more perforating arteries to the limen insulae than any other cortical artery and supplied it in 30% of the hemispheres. (Images courtesy of AL Rhoton, Jr.)