External iliac artery
The external iliac artery is the larger terminal branch of the common iliac artery (Read more!). It is a paired vessel that provides the main arterial supply to the lower limb through its continuation as the femoral artery (Read more!).
The common iliac artery bifurcates at the level of the pelvic brim, anterior to the sacroiliac joint. From this point, the external iliac artery travels anteroinferiorly along the medial border of the psoas major muscle (Read more!) toward the inguinal ligament (Read more!).
The external iliac artery exits the pelvic cavity by passing under the inguinal ligament at its middle portion. It travels through the vascular lacuna. Once the artery enters the lower limb, it continues as the femoral artery. The exit point of the external iliac artery is lateral to the insertion site of the inguinal ligament on the pubic tubercle (roughly one-third of the way along the line between the pubic tubercle and the anterior superior iliac spine).
The external iliac artery serves as a short conduit between the common iliac artery and the femoral artery. It does not directly supply any structures. However, it gives rise to two branches before passing beneath the inguinal ligament. They are as follows:
- Inferior epigastric artery (Read more!) - arises from the medial side of the external iliac artery and ascends along the posterior surface of the rectus abdominis muscle;
- Deep circumflex iliac artery (Read more!) - originates from the lateral side of the external iliac artery and courses laterally along the inguinal ligament and iliac crest.
These branches supply arterial blood to the muscles and structures of the inferior aspect of the anterolateral abdominal wall. However, the majority of blood flow continues into the femoral artery, which further distributes it to the lower limb.