Internal Iliac Artery Anatomy

Internal Iliac Artery Anatomy

• Focuses on the arterial supply to the pelvic viscera.
• The arterial supply differs between males and females due to different organs.
• The pelvic arterial supply is rich, variable, and has anastomoses.
• Describes the branches of the internal iliac artery.

Origin and Divisions of the Internal Iliac Artery

• The abdominal aorta ends by dividing into the left and right common iliac arteries.
• The common iliac artery divides into the external iliac artery (supplying the lower limb) and the internal iliac artery.
• The ureter crosses over one of the iliac vessels.
• The internal iliac artery divides into anterior and posterior divisions.
• The anterior division primarily supplies the pelvic viscera.
• The posterior division supplies the muscles in the posterior pelvis.

Branches of the Anterior Division

• Key function is to supply blood to the pelvic viscera.
• Superior Vesical Arteries: Supply the superior bladder; the first branch encountered; were the umbilical arteries in the fetus.
• Obturator Artery: Runs with the obturator nerve and vein, passing through the obturator canal to supply the medial thigh.
• Inferior Vesical or Vaginal Arteries:
  • In makes: Inferior Vesical Arteries supply the lower bladder.
  • In females: Vaginal Arteries supply the vagina and the inferior bladder.
• Uterine Artery (Female Only): Supplies blood to the uterus, uterine tubes, and ovaries.
  • Ascends along the sides of the uterus.
  • Includes a branch to the vagina, and a branch to the uterine tubes and ovary.
  • The ureter is inferior to the uterine artery.
• Middle Rectal Artery: Supplies blood to the rectum and may branch directly from the anterior trunk or another branch.
• Internal Pudendal Artery: A terminal branch; passes through the greater and lesser sciatic foramina to reach the perineum.
  • Supplies the perineum and external genitalia, including erectile tissues.
  • Gives off the inferior rectal artery.
• Inferior Gluteal Artery: A terminal branch that supplies blood to the gluteal region.

Rectal Artery Blood Supply

• Superior Rectal Artery: A branch of the inferior mesenteric artery (from the aorta), supplying the hindgut.
• Middle and Inferior Rectal Arteries: Arise from the internal iliac artery.
• These vessels anastomose around the rectum and anal canal.
• Rectal veins also form anastomoses.

Greater and Lesser Sciatic Foramen

• The greater sciatic foramen allows structures to exit the pelvis.
• The lesser sciatic foramen allows structures to re-enter the pelvis to reach the perineum.
• The internal pudendal artery exits the pelvis through the greater sciatic foramen and re-enters through the lesser sciatic foramen.
• It runs past the levator ani muscle to reach the perineum.

Pudendal Nerves and Arteries

• There is only one pudendal nerve.
• There is an internal pudendal artery (a branch of the internal iliac artery).
• External pudendal arteries (superficial and deep) originate from the femoral artery outside the pelvis.

Branches of the Posterior Division

• Key function is to supply blood to the posterior muscles.
• Iliolumbar Artery: Supplies blood to the iliopsoas major and quadratus lumborum muscles.
• Lateral Sacral Arteries: Run along the sacrum, supplying blood to the meninges and the erector spinae muscles.
• Superior Gluteal Artery: Passes through the greater sciatic foramen superior to the piriformis muscle; it's a branch of the posterior division.
• Piriformis Muscle: Landmark for gluteal artery location; the sciatic nerve usually exits inferior to piriformis, but it can sometimes go through it.
• Inferior Gluteal Artery: Comes off of the anterior division of the internal iliac artery and passes through the greater sciatic foramen inferior to the piriformis muscle.