The internal iliac artery is an important blood vessel that supplies the organs and tissues of the pelvic region. It originates as one of the two branches into which the common iliac artery divides; the other is the external iliac. It gives off many arterial branches of tortuous course that supply the bladder, genitals, uterus, rectum, muscles of the perineal region, as well as the gluteus maximus and piriformis muscle.
As soon as it arises from the common iliac, the internal iliac artery descends obliquely and medially into the cavity of the true pelvis along the line of the sacro-iliac joint. Then, at the upper border of the greater sciatic foramen, it forks into an anterior and a posterior trunk. All the the arteries arising from the anterior trunk are viseral branches, while those originating from the posterior trunk are parietal offshoots, with the exception of the inferior gluteal and obturator artery, which are the only parietal branches arising from the anterior trunk.
Branches of Internal Iliac Artery
1) Umbilical Artery. It is one of its largest branches in the embryonic period. It arises from the anterior trunk of the internal iliac and runs forwards to the wall of pelvis. Then it gives off the superior vesical arteries, which supply the urinary bladder and the ureter.
2) Uterine Artery/of the vas deferens. It originates from the anterior trunk and extends under the peritoneum forwards and medially. In the female, it irrigates the uterus; in males, the vas deferens duct and the seminal vesicles.
3) Middle Rectal Artery. It arises also from the anterior trunk of internal iliac as a small blood vessel that sometimes is absent in some individuals. However, it sometimes originates from the inferior vesical artery.
4) Internal Pudendal Artery. It is an offshoot of the anterior trunk of internal iliac. It has a rather long an tortuous course, giving off several smaller branches that supply the external genitalia and the perineum.
5) Iliolumbar Artery. It arises from the posterior trunk. Running forwards and upwards, it sends terminal branches to the pelvic muscles and bone.
6) Lateral Sacral Arteries. They spring off the posterior trunk; then they run medially to supply the sacrum, the skin of the sacral region, deep muscles of the lower back, and the piriformis, coccygeus, and levator ani muscles.
7) Superior Gluteal Artery. It also arises from the posterior trunk as a large branch. It leaves the cavity of the pelvis through the greater sacrosciatic foramen, giving off branches to the piriformis, and the gluteus maximus and the gluteus medius.
8) Inferior Gluteal Artery. It is the only parietal branch that arises from the anterior trunk of internal iliac. It supplies the gluteus maximus and quadratus femoris muscle.
9) Obturator Artery. It branches from the anterior trunk. Running on the side wall of the true pelvis, it gives off smaller arteries to supply the external obturator muscle.
Below, schematic picture of blood vessels of pelvis region, exhibiting the internal iliac artery.
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