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The external iliac artery is a blood vessel of the human hip region. A bilateral vessel, meaning that one is found on either side of the body, it originates from the common iliac artery near the base of the spine and approaches the upper leg before becoming the femoral artery. The external iliac artery delivers blood via various branches of the femoral artery to the entire lower limb, blood that supplies the tissues of the leg and foot with vital nutrients and oxygen.
All blood that flows toward the lower half of the body comes from the aorta, the body’s largest artery that exits the heart directly. Blood in the arteries, which carry it away from the heart, flows from larger to smaller vessels. The aorta takes blood that has been pumped through the lungs to receive fresh oxygen and distributes it throughout the body via smaller branches. As it heads downward through the abdomen directly in front of the spine, its first bifurcation — that is, the first place where it splits into two branches — is into the right and left common iliac arteries. The common iliac artery corresponds with the height of the top of the iliac bone of the pelvis.
Splitting off toward either leg, the common iliac artery proceeds downward and outward for a short distance before encountering a bifurcation of its own: the internal and external iliac arteries. While the internal iliac artery supplies many of the tissues of the pelvis, such as the reproductive organs, the gluteal muscles, and the skin of the buttocks, the external iliac artery angles forward on its path toward the leg. Running alongside the inside edge of the psoas major, a hip flexor muscle, this vessel begins near the sacroiliac joint, or the place where the sacrum bone of the lower spine meets the iliac bones in the posterior pelvis.
Aside from the psoas major to its outside and slightly behind it, the external iliac artery is surrounded by numerous other structures on its course through the pelvis. Keeping in mind that the artery is angling forward and therefore crossing the pelvis obliquely as it descends, it passes behind the peritoneum, the membrane containing the organs and other contents of the pelvic cavity. Above the artery near its origin point, the male spermatic or female ovarian vessels pass over it. Below it, the corresponding external iliac vein carries blood back toward the heart.
The external iliac artery never exits the pelvis, at least not under the same name. It courses only a few inches through the interior of the pelvis before it passes beneath the inguinal ligament. The inguinal ligament corresponds with the crease of the same name that is formed where the leg meets the hip and is visible upon flexing the leg forward at the hip. It runs obliquely from the anterior superior iliac spine, or the crest on the front of the pelvis commonly referred to as the “hipbones,” toward the pubic tubercle, a surface on the pubis bone where the leg meets the groin. Upon crossing beneath this ligament at its approximate midpoint, the external iliac artery becomes known as the femoral artery, the large vessel that supplies blood to the leg.