L) Arteries Of The Pelvis

Common Iliac Arteries

The common iliac arteries arise as the bifurcation of that abdominal aorta, at about the level of the L4 vertebral body.
The right common iliac has a longer course than the left, passing anterior to the union of the common iliac veins to reach the right psoas muscle. It then passes medial to the psoas muscle to the pelvic brim, dividing into the right external iliac and internal iliac arteries.
The left common iliac has a shorter course, and passes slightly inferiorly and left lateral to reach the medial border of the psoas muscle. It descends to the pelvic brim and divides into the left external and internal iliac vessels.
The bifurcation of the common iliacs into external/internal vessels is an important landmark. It occurs at the level of the L5-S1 intervertebral disc. In men, the testicular artery passes over its surface. The ureter also crosses over the bifurcation to enter the pelvis.

External Iliac Arteries

The paired external iliac arteries follow a relatively similar course on both sides. They continue their relationship to the medial border of psoas, and pass anterior and lateral over the pelvic inlet. They lie anterior to the accompanying external iliac vein. The branches of the external iliac are two small vessels, the inferior epigastric and the deep circumflex iliac arteries which both supply the anterolateral abdominal wall.
The external iliac exits the abdomen beneath the inguinal ligament, separated from the psoas by its fascia and the femoral nerve, with the external iliac vein lying medial. Upon entering the femoral triangle it becomes the common femoral artery, discussed elsewhere.

Internal Iliac Arteries

The paired internal iliac arteries pass inferiorly along the pelvic side wall, supplying the pelvic organs, the gluteal region and the perineum.
Each iliac artery divides into anterior and posterior trunks shortly after arising.
The posterior trunk is smaller and gives off the lateral sacral artery (which supplies the piriformis muscle and skin of the back), the iliolumbar artery (which supplies the iliopsoas and cauda equina) and then continuing as superior gluteal artery. This larger vessel exits the pelvis through the greater sciatic notch, superior to the piriformis muscle, and supplies that muscle as well as the gluteal muscles.
The anterior trunk has numerous branches:

  • The superior vesical artery (the first part of which is the distally obliterated umbilical artery), which passes medially to supply the superior part of the urinary bladder
  • The obturator artery, which passes anteriorly along the internal obturator muscle to reach the obturator canal and exit the pelvis. It supplies the obturator muscles, the femoral head and the adductor thigh muscles. It travels with the obturator nerve, a branch of the lumbar plexus.
  • The inferior vesical artery (in men only), which passes to the inferior aspect of the bladder. It also contributes to the supply of the prostate gland and the seminal glands.
  • In women, the inferior vesical is replaced by the uterine artery. This artery passes in the inferior part of the broad ligament, crossing the ureter at the level of the cervix, and then ascending in the mesometrium to the origin of the uterine tubes.
  • The vaginal artery, usually a branch of the uterine before it crosses the ureter, descends to supply the inner two thirds of the vagina and pelvic floor muscles.
  • The middle rectal artery, one of the distal branches, passes medially along levator ani to reach the distal third of the rectum. Small branches may supply the prostate gland.
  • The pudendal artery, one of the terminal branches, continues the course of the anterior trunk and exits the pelvis through the greater sciatic foramen. Curving around the ischial spine, it enters the perineum through the inferior sciatic foramen. Giving off the inferior rectal artery which supplies the rectum and anal canal, it continues anteriorly along the inferior part of obturator internus, within the ischioanal fossa. Small perineal branches may contribute to the prostate; scrotal branches supply the skin of the prostate, and the artery terminates as the deep and dorsal arteries of the penis/clitoris.
  • The inferior gluteal artery also exits through the sciatic notch, inferior to the piriformis muscle. It supplies the gluteus maximus and the pelvic floor muscles.