Topography of the iliac arteries
The iliac vascular system begins at the aortic bifurcation. Each common iliac artery subsequently divides into external and internal branches.
External iliac artery (a. iliaca externa) serves as the direct continuation of the common iliac artery. Its topographical course runs strictly along the pelvic brim toward the midpoint of the inguinal ligament. Passing through the vascular lacuna (lacuna vasorum) located beneath this ligament, the vessel enters the thigh, where it changes its name and continues as the femoral artery. Along its course, it gives off muscular branches supplying the iliopsoas muscle (m. iliopsoas), as well as two important branches: the inferior epigastric artery (a. epigastrica inferior) and the deep circumflex iliac artery (a. circumflexa ilium profunda).
Internal iliac artery (a. iliaca interna) descends retroperitoneally along the lateral wall of the lesser pelvis. Its main anatomical landmark is the greater sciatic foramen. Upon reaching the upper margin of this foramen, this large vessel divides into two main trunks: the anterior and posterior branches.
Parietal branches of the abdominal aorta
Since the iliac vessels originate from the abdominal aorta, understanding the region's blood supply requires examining its branches. Parietal vessels supply the cavity walls and muscle masses.
- Inferior phrenic arteries (aa. phrenicae inferiores dextra et sinistra): arise from the anterior surface of the initial segment of the abdominal aorta. They ascend, running anteriorly and laterally, and rest on the abdominal surface of the diaphragm.
- Lumbar arteries (aa. lumbales): four pairs of vessels branching from the posterior wall of the aorta along the first four lumbar vertebrae. They supply blood to the lateral abdominal wall, lumbar region, and spinal cord.
- Median sacral artery (a. sacralis mediana): a slender unpaired vessel. It originates at the level of the fifth lumbar vertebra (L5), directly from the posterior surface of the aorta at its bifurcation. It descends strictly along the midline of the pelvic surface of the sacrum down to the coccyx, giving off branches to the iliopsoas muscle (m. iliopsoas), the sacrum itself, and the coccyx.
Unpaired visceral branches
The internal (visceral) unpaired branches supply arterial blood to the gastrointestinal organs.
- Celiac trunk (truncus celiacus): a short but robust vessel arising from the anterior surface of the aorta at the level of the twelfth thoracic vertebra (TXII). It immediately divides into three arteries: the left gastric (a. gastrica sinistra), common hepatic (a. hepatica communis), and splenic (a. lienalis).
- Superior mesenteric artery (a. mesenterica superior): arises anteriorly at the level of the first lumbar vertebra (LI). The vessel emerges from beneath the lower border of the neck of the pancreas, crosses the anterior surface of the ascending part of the duodenum (D3 segment), and enters the root of the mesentery of the small intestine. It supplies the pancreas, duodenum, the entire mesenteric part of the small intestine, and the proximal large intestine.
- Inferior mesenteric artery (a. mesenterica inferior): arises from the anterior wall of the lower third of the aorta at the level of the third lumbar vertebra (LIII). It runs retroperitoneally and gives off the left colic (a. colica sinistra), sigmoid (aa. sigmoideae), and superior rectal (a. rectalis superior) arteries.
Paired visceral branches
Paired visceral branches supply symmetrical organs of the retroperitoneal space and the reproductive system.
- Middle suprarenal artery (a. suprarenalis media): branches from the lateral surface of the aorta just below the origin of the superior mesenteric artery and runs toward the adrenal gland.
- Renal arteries (aa. renales): major trunks running to the kidneys.
- Testicular or ovarian arteries (aa. testiculares / aa. ovaricae): slender paired vessels originating on the anterior surface of the aorta below the renal arteries. They descend retroperitoneally, crossing the ureters and external iliac arteries. In men, they pass through the inguinal canal to the testis; in women, they run within the suspensory ligament of the ovary toward the ovaries and uterine tubes.
Briefly: answers to topical questions
Which specific vessels branch from the anterior and posterior trunks of the internal iliac artery?
Visceral and parietal branches arise from the anterior and posterior trunks of the internal iliac artery.
The anterior trunk gives rise to:
- Umbilical artery (a. umbilicalis) — gives off superior vesical arteries.
- Inferior vesical artery (a. vesicalis inferior) — lies deeper than the umbilical artery.
- Uterine artery (a. uterina) — a visceral branch.
- Middle rectal artery (a. rectalis media) — located on the pelvic diaphragm.
- Obturator artery (a. obturatoria) — enters the obturator canal.
- Internal pudendal artery (a. pudenda interna) — passes through the infrapiriform foramen.
- Inferior gluteal artery (a. glutea inferior) — terminal branch of the anterior trunk.
The posterior trunk gives rise to:
- Iliolumbar artery (a. iliolumbalis) — divides into lumbar and iliac branches.
- Superior gluteal artery (a. glutea superior) — passes through the suprapiriform foramen.
Which arteries are involved in the blood supply to the rectum?
The rectum is supplied by the following vessels:
- Superior rectal artery (a. rectalis superior) — the terminal branch of the inferior mesenteric artery, running toward the ampulla of the rectum.
- Middle rectal arteries (aa. rectales mediae) — located on the pelvic diaphragm.
- Inferior rectal arteries (aa. rectales inferiores) — pass through the ischioanal fossa (fossa ischiorectalis) in the frontal plane.
Which vessels form the "corona mortis" in atypical branching?
The "corona mortis" (corona mortis) is formed by an anastomosis between branches of the external and internal iliac arteries.
This vascular connection is formed by:
- Obturator artery (a. obturatoria) — gives off a pubic branch (r. pubicus).
- Inferior epigastric artery (a. epigastrica inferior) — gives off its own pubic branch (r. pubicus), which connects with the branch of the obturator artery.
- External iliac artery (a. iliaca externa) — may directly participate in forming the anastomosis with the obturator artery.
This anatomical variant occurs in 25–35% of patients and carries a high risk of massive hemorrhage during pelvic trauma and surgical approaches.
For quick memorization of the three branches of the celiac trunk (truncus celiacus), it is convenient to use the mnemonic LOS: Left gastric, Ommental / common hepatic, Splenic arteries.
Class and exam questions
At what level does the median sacral artery originate?
It arises from the posterior surface of the aorta at its bifurcation, which corresponds to the level of the fifth lumbar vertebra (L5).
Through which anatomical structure does the external iliac artery enter the thigh?
The vessel passes beneath the inguinal ligament through the vascular lacuna (lacuna vasorum), after which it continues as the femoral artery.
Which organs are supplied with blood by the superior mesenteric artery?
It supplies branches to the pancreas, duodenum, the entire mesenteric part of the small intestine, and the proximal large intestine.
Where does the internal iliac artery divide into its branches?
Division into anterior and posterior branches occurs at the level of the upper margin of the greater sciatic foramen.
What else to study on this topic
- Topography and branches of the anterior trunk of the internal iliac artery
- Topography and branches of the posterior trunk of the internal iliac artery
- Anastomoses between the branches of the superior and inferior mesenteric arteries
- Formation and boundaries of the vascular lacuna (lacuna vasorum)
- Specific features of the spinal cord blood supply by lumbar arteries
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