Common iliac artery
The paired common iliac artery (a. iliaca communis) originates from the bifurcation of the abdominal aorta. This division occurs strictly at the level of the IV lumbar vertebra.
Once formed, the vessel runs inferiorly and laterally, reaching the region of the sacroiliac joint. The average length of this segment ranges from 5 to 7 centimeters. Throughout its course, the artery gives off several small branches that supply blood to:
- Lymph nodes of the pelvis and abdominal cavity;
- Ureter;
- Psoas major muscle (m. psoas major).
In the region of the sacroiliac joint, the common iliac artery finally divides into two large trunks: the external (a. iliaca externa) and internal (a. iliaca interna) iliac arteries.
Topography of the external iliac artery
The external iliac artery (a. iliaca externa) is the direct continuation of the common iliac artery. Its main course runs along the medial margin of the psoas major muscle (m. psoas major).
Having reached the inguinal ligament, the artery passes beneath it through the vascular lacuna. Immediately after crossing this anatomical border, it changes its name and continues as the femoral artery (a. femoralis), heading toward the structures of the lower limb.
Branches of the external iliac artery
Before emerging onto the thigh, the external iliac artery gives off two important branches that supply the anterior abdominal wall and adjacent structures.
1. Inferior epigastric artery (a. epigastrica inferior) It arises from the main trunk just above the inguinal ligament. The vessel ascends along the posterior surface of the anterior abdominal wall and enters the rectus sheath (m. rectus abdominis).
- Anastomoses: Forms a crucial collateral pathway by anastomosing with the superior epigastric artery (a. epigastrica superior), which is a branch of the internal thoracic artery.
- Pubic branch (r. pubicus): Runs toward the pubic symphysis. Frequently anastomoses with the obturator artery — this vascular connection has historical significance as corona mortis ("crown of death") due to the risk of fatal hemorrhage during surgical interventions.
- Branches to reproductive structures: In males, it gives off the cremasteric artery (a. cremasterica); in females, the artery of the round ligament of the uterus (a. lig. teretis uteri). They pass through the superficial inguinal ring. In males, the vessel anastomoses with the testicular artery (a. testicularis); in females, with uterine branches.
2. Deep circumflex iliac artery (a. circumflexa ilium profunda) This branch runs laterally, parallel to the inguinal ligament. Then it ascends along the iliac crest, located in the muscular layer between the internal oblique and transversus abdominis muscles.
- Anastomoses: Connects with branches of the iliolumbar artery (a. iliolumbalis) and lumbar arteries (aa. lumbales).
Briefly: answers to topical questions
In which peritoneal fold does the inferior epigastric artery run on the inner surface of the anterior abdominal wall?
The inferior epigastric artery runs within the lateral umbilical fold (plica umbilicalis lateralis). This fold is paired and located on the inner surface of the anterior abdominal wall superior to the inferior epigastric vessels (a. et v. epigastricae inferiores). It represents the only fold in this region that contains functioning blood vessels.
Which muscles are supplied by the deep circumflex iliac artery?
The deep circumflex iliac artery (a. circumflexa ilium profunda) supplies the muscles of the anterolateral abdominal wall and pelvis.
The muscles supplied by it include:
- Transversus abdominis muscle (m. transversus abdominis) — the artery runs between it and the internal oblique muscle.
- Internal oblique muscle of the abdomen (m. obliquus internus abdominis) — receives branches along the course of the vessel along the iliac crest.
- Iliacus muscle (m. iliacus) — supplied within the iliac fossa.
The artery also gives off branches to the iliac bone itself.
How is the external iliac vein positioned relative to the external iliac artery within the vascular lacuna?
Within the vascular lacuna, the external iliac vein (v. iliaca externa) lies medial to the external iliac artery (a. iliaca externa).
The femoral vein, passing beneath the inguinal ligament through the vascular lacuna (lacuna vasorum), lies medial to the artery and directly continues as the external iliac vein. Throughout its further course, the external iliac vein follows the path of the artery, maintaining its position medial to it until joining the internal iliac vein.
The level of formation of the common iliac arteries is easy to remember by the number 4: the aortic bifurcation occurs at the level of the IV lumbar vertebra.
Class and exam questions
Where does the external iliac artery transition into the femoral artery?
The transition occurs as the artery passes beneath the inguinal ligament through the vascular lacuna.
With which artery does the inferior epigastric artery anastomose within the substance of the rectus abdominis muscle?
It forms a robust anastomosis with the superior epigastric artery, creating an important collateral pathway for blood flow.
What is corona mortis?
This is an anastomosis between the pubic branch of the inferior epigastric artery and the obturator artery in the region of the pubic symphysis.
What else to study on this topic
- Boundaries and contents of the vascular lacuna
- Internal iliac artery: parietal and visceral branches
- Collateral circulation of the anterior abdominal wall
- Topography of the rectus sheath
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