Obturator artery

After passing through the obturator canal and outside of the pelvis, the obturator artery divides at the upper margin of the obturator foramen, into an anterior branch and a posterior branch of the obturator artery which encircle the foramen under cover of the obturator externus.

The anterior branch of the obturator artery is a small artery in the thigh and runs forward on the outer surface of the obturator membrane and then curves downward along the anterior margin of the obturator foramen.

It distributes branches to the obturator externus, pectineus, adductors, and gracilis muscle, and anastomoses with the posterior branch and with the medial femoral circumflex artery.

The posterior branch of the obturator artery is a small artery in the thigh and follows the posterior margin of the foramen and turns forward on the inferior ramus of the ischium, where it anastomoses with the anterior branch.

It gives twigs to the muscles attached to the ischial tuberosity and anastomoses with the inferior gluteal artery. It also supplies an articular branch which enters the hip-joint through the acetabular notch, ramifies in the fat at the bottom of the acetabulum and sends a twig along the ligament of head of femur (ligamentum teres) to the head of the femur.

The blood supply to the femoral head and neck is enhanced by the artery of the ligamentum teres derived from the obturator artery. In adults, this is small and doesn't have much importance, but in children whose epiphyseal line is still made of cartilage (which doesn't allow blood supply through it), it helps to supply the head and neck of the femur on its own.

The articular branch is usually patent until roughly 15 years of age. In adults it does not provide enough blood supply to prevent avascular necrosis in upper femur fractures.

Inferior epigastric origin of the obturator artery, a normal variant. (A) shows a course abutting the external iliac vein, clear of the femoral ring. (B) shows the corona mortis variant, where artery courses within the lacunar ligament before diving through fascia inferiorly.

The obturator artery usually arises from the main stem or from the anterior trunk of the internal iliac artery.[1][2] It may arise from the superior gluteal artery, and occasionally it arises from the external iliac.

In about two out of every seven cases it arises from the inferior epigastric and descends almost vertically to the upper part of the obturator foramen. The artery in this course usually lies in contact with the external iliac vein, and on the lateral side of the femoral ring (Figure A on diagram). It can also pass medial to the femoral ring along the margin of the lacunar ligament (Figure B). In either case it would be at risk of injury during the operation to repair a femoral hernia, whether the hernia is reducible, incarcerated or strangulated. When the obturator artery travels along the lacunar ligament, it nearly encircles the femoral ring and can be lacerated during a femoral hernia repair. Most femoral hernias are repaired through a small (1/2 to 3/4 inch) incision in the groin area, rather than through the abdomen, so if a laceration were to occur, bleeding may not be immediately recognized and result in significant blood loss into the peritoneal cavity. Because of this danger, the anatomic variant in Figure B is sometimes referred to as the "crown of death" (corona mortis) .[3][4]