Arterial structures:Pelvis:Internal iliac artery

The**internal iliac artery** is the smaller terminal branch of the common iliac artery.

It supplies:

* pelvic walls
* pelvic viscera,
* external genitalia
* perineum
* buttock
* medial part of the thigh.

These lie within the parietal pelvic fascia and only their branches pass out of the pelvis.

Origin and course:

* The common iliac artery bifurcates into the internal iliac artery and external iliac artery at the level of the *pelvic brim* anterior to the sacroiliac joint.
* The internal iliac artery courses posteromedially towards the greater sciatic foramen. It is approximately 4 cm in length.
* At the *superior margin of the greater sciatic foramen* it divides into an anterior division and posterior division.
* The anterior division continues down to the ischial spine anterior to piriformis giving off visceral and parietal branches. The posterior division only gives rise to parietal branches.

Relations

* anteriorly: ureter, ovary, uterine tube
* posteriorly: lumbosacral trunk, sacroiliac joint
* medially: peritoneum
* laterally: external iliac vein, obturator nerve

Branches

Anterior division: nine branches - three bladder, three visceral, three parietal (ordered below)

* **umbilical artery (only patent in the foetus)**
* **superior vesical artery (branch of the umbilical artery):** run along side wall of pelvis, then turns medially to reach upper part of the bladder and supplies ureter and vas.
* **inferior vesical artery:** runs medially across the pelvic floor to supply trigone, lower part of bladder, ureter, vas, seminal vesicle and prostate.
* **vaginal artery:** supply upper part of vagina and correspond to inferior vesical artery in male
* **uterine artery:** cross pelvis at the base of the broad ligament, pass above ureter. Turns upwards at cervix and alongside of uteru to the cornu and turn laterally to supply tube and anastomose with tubal branch of ovarian artery.
* **middle rectal artery:** supply muscle of rectum. May be replaced by small branch from an artery that supplies other pelvic viscera.
* **obturator artery (25% will branch off the inferior epigastric artery):** pass along side wall of pelvis, enter obturator foramen and into the medial thigh.
* **internal pudendal artery (supplies the external genitalia):** lies in front of the inferior gluteal, passes through the greater sciatic foramen below piriformis. It is distributed to anal region and external genitalia.
* **inferior gluteal artery:** runs backwards, passes below S1 nerve root and leaves pelvis through the greater sciatic formane below priformis.

Posterior division: all parietal

* **iliolumbar artery:** pass upwards out of pelvis in front of lumbosacral trunk, running laterally deep to psoas. Supplies quadratus lumborum, psoas, erector spinae and L5 segment.
* **lateral sacral arteries:** runs down lateral to anterior sacral foramina. It supplies roots and pirifiormis. Spinal branches enter the foramina, supply meninges.
	+ superior and inferior branches - supply 1-2, and 3-4 sacral segment respectively
* **superior gluteal artery:** largest branch, pass backwards through the greater sciatic foramen above piriformis.

Variant anatomy

* Persistent sciatic artery
* No anterior/posterior division
* Common hypogastric trunk giving off SVA, IVA, MRA, and uterine.
* superior gluteal artery (SGA) first branch and internal pudendal + IGA off a common branch
* SGA and IGA off a common branch
* SGA, IGA and internal pudendal separate branches
* Common trunk off ILA and SGA off it first then internal pudendal and IGA off a common
* SGA and internal pudendal of a common trunk and internal pudendal separately