Posterior division of internal iliac artery

At a glance

English

Posterior division of internal iliac artery

Latin (TA2)

Divisio posterior arteriae iliacae internaecus

System

Artery

Region

Trunk

Side

Paired, left and right

About the posterior division of internal iliac artery

Near the upper edge of the greater sciatic foramen the internal iliac artery usually splits into two trunks. The posterior division, or posterior trunk, is the shorter one. It runs backwards towards the sacrum and sciatic foramen and supplies the wall of the pelvis and the buttock, but none of the pelvic organs; all the visceral branches come from the anterior trunk. The pattern of branching varies, and the division may be absent when branches arise one by one from the parent.

Its branches are usually three. The iliolumbar artery turns upwards out of the pelvis behind the obturator nerve and the external iliac vessels and divides behind psoas major into lumbar and iliacus branches. The lateral sacral arteries, generally an upper and a lower, run medially and down in front of the sacral nerve roots and send spinal branches through the anterior sacral foramina. The trunk then continues as the superior gluteal artery, its largest branch.

The superior gluteal artery passes backwards between the lumbosacral trunk and the first sacral nerve, or between the first and second sacral nerves, and leaves the pelvis through the greater sciatic foramen above piriformis. In the buttock it splits into a superficial branch to gluteus maximus and a deep branch that runs between gluteus medius and minimus, supplying them and tensor fasciae latae.

Through the iliolumbar and lateral sacral arteries the trunk links with the last lumbar and median sacral arteries from the aorta, which helps keep the pelvis supplied if the internal iliac is tied. Because it lies directly on the sacral plexus and close to the sciatic notch, the posterior trunk is at risk when pelvic fractures widen the sacroiliac joint or the sciatic notch; injury to the superior gluteal artery here can cause heavy bleeding that may be controlled by blocking the vessel through a catheter. It must also be spared when the internal iliac artery is blocked for pelvic bleeding, if the buttock muscles are to keep their supply.

Course and supply

Arises from

One of the two trunks into which the internal iliac artery divides near the upper border of the greater sciatic foramen.

Ends in

Gives the iliolumbar and lateral sacral arteries and continues as the superior gluteal artery.

Supplies

Supplies the posterior pelvic wall, the sacral canal, the iliac fossa and lower lumbar region, and the gluteal muscles.