The iliac artery is a collective term for the common, internal, and external iliac arteries found on both sides of the pelvis. An artery is a blood vessel that transports blood away from the heart, as opposed to a vein, which takes blood to the heart. The iliac artery delivers oxygenated blood to the organs of the pelvis, an area of the body situated below and behind the abdomen and above the legs. As paired structures, these arteries are present on both the right and left sides of the body.
At about the level of the hip, the abdominal aorta splits into the left and right common iliac arteries, which travel away from each other inferolaterally, or downwards and to the sides. The abdominal aorta is a major artery that extends into the abdomen from the heart. The place at which it divides into the common iliac artery is called the aortic bifurcation. This is located at the fourth lumbar vertebrae, or at about the level of the iliac crest. The iliac crest is the top ridge of the ilium, the uppermost bone in the hip.
The common iliac arteries run along the inside of the psoas muscles, paired muscles that run down along the spine and angle out at the level of the sacrum to connect with the femur. The sacrum is the fused part of the spine just above the tailbone and the femur is the large bone in the thigh that connects with the acetabulum of the hip. The acetabulum is a socket formed by the convergence of the three paired bones of the hip; the ilium on top, the ischium on the lower outside, and the pubis on the lower inside.
This artery branches into the external and internal arteries along the pelvic brim at the level of the sacroiliac joint, where the ilium joins with the sacrum. The pelvic brim is the inner rim of the pelvic bones. The internal artery runs downward through a hole in the pelvis called the greater sciatic foramen, where it splits into anterior and posterior branches. The artery continues to divide into smaller vessels that transport blood to the ilium, back muscles, internal reproductive organs, external reproductive organs in men, pelvic muscles, the muscle and skin of the buttocks, the hip joint, the urinary bladder, the rectum, and the alimentary canal. Its large role in delivering oxygen-rich blood to the organs of the pelvis makes the internal iliac arteries the principal arteries in the region.
The external iliac artery travels down toward the thigh bone in a diagonal path that runs both to the front and side of the body. It divides into three branches: the inferior epigastric artery, the deep circumflex iliac artery, and the femoral artery. The first two arteries deliver blood to the skin and muscle of the lower abdomen. The femoral artery is responsible for most of the blood flow to the legs.