There are dual arterial supplies to the groin flap that consist of the superficial circumflex iliac artery (SCIA) and the superficial epigastric artery (SEA). Both arteries form complex vascular patterns in nourishing the groin flap. In a typical case, the separate SCIA and SEA originate directly from the femoral artery, but on some occasions, their points of origin vary from the profunda femoris, the deep circumflex iliac artery and so on. In 16% of cadaver dissections, either or both the SCIA and the SEA emerged from arteries other than the femoral artery (1, 4).

In 30% to 50% of cases, the SCIA and SEA together form a single common trunk at their origin, but they are of separate origin in the remainder of cases. The SCIA is constant, with a reliable anatomic course, but the SEA occasionally is deficient. Both arteries form a closed vascular network in nourishing the groin skin, and a free groin flap can therefore be isolated with a pedicle of either of the arteries or the common trunk.

There are two venous drainage systems in the groin. The dominant venous system is usually composed of the superficial cutaneous veins involving the superficial circumflex iliac vein and the superficial epigastric vein. In more than 60% of cases, both veins form a common trunk and flow into the saphenous bulb after crossing over the femoral artery. When both veins are duplicated or branch farther out, the dominant venous
flow usually is maintained by the superficial circumflex iliac vein. The deep veins, such as the venae comitantes of the two arteries, are additional drainage systems in the groin and can, in some cases in which the superficial veins do not develop well, be reliable drainage veins.