Diagram of the Insular Areas Drained by the Superficial and Deep Venous Systems. A, The territory drained by the deep venous system is shaded purple, whereas that drained by the superficial venous system is light blue. The limen area, inferior limiting sulcus, long gyri, and central insular sulcus are drained by the deep MCV (purple area). The SSV drained the middle short gyrus and insular apex more commonly than any other insular area (light blue area). The transitional zone, which is usually drained by both the superficial and deep venous systems, included the anterior and posterior short gyri and the anterior limiting sulcus (stippled area). These transitional areas emptied three to eight times more frequently into the deep MCV than the SSV. B, Diagram of areas drained by insular veins. See Table 8 for a listing of the insular areas drained by the four insular veins. The territory drained by each insular vein is shaded a different color: anterior insular vein (dark green), precentral insular vein (light green), central insular vein (light blue), and posterior insular vein (dark blue). The areas having significant anastomotic connections with the SSV are stippled. The anterior insular vein drained the anterior limiting sulcus and the anterior short gyrus (dark green area). Although the anterior short gyrus was drained by the anterior insular vein in the majority of hemispheres, the frontosylvian veins contributed to drainage in almost half of the cases (stippled area). The precentral insular vein drained the middle short gyrus and insular apex and displayed more anastomoses with the SSV than any other insular vein. The frontosylvian veins contributed to drainage of the middle short gyrus and insular apex in more than 80% of the hemispheres (stippled area). The central insular vein drained the posterior short and anterior long gyri and the central insular sulcus in almost 90% of the specimens (light blue). The posterior insular vein exclusively drained the posterior long gyrus and the inferior limiting sulcus (dark blue). The most complicated pattern of insular drainage was in the limen area (light and dark blue areas), which was drained by a combination of the central and posterior insular veins in more than half of the cases and by the posterior insular vein alone in the other 40% of cases. The limen area is the only one drained almost solely by the deep venous system without any contribution from the SSV. (Images courtesy of AL Rhoton, Jr.)