iliolumbar artery iliolumbar artery the iliolumbar artery is the first branch of the posterior trunk of the internal iliac artery. iliolumbar arterythe veins of the right half of the male pelvis. (iliolumbar artery not labeled, but iliolumbar vein visible at center right.)detailssourceinternal iliac arteryveiniliolumbar veinidentifierslatinarteria iliolumbalista98a12.2.15.002ta24304fma18845anatomical terminology structure the iliolumbar artery is the first branch of the posterior trunk of the internal iliac artery. it turns upward behind the obturator nerve and the external iliac artery and vein, to the medial border of the psoas major muscle, behind which it divides into: lumbar branch of iliolumbar artery iliac branch of iliolumbar artery anastomoses 1. last lumbar→iliolumbar 2. lateral sacral↔lateral sacral 3. middle sacral→lateral sacral 4. superior hemorrhoidal→middle hemorrhoidal 5. medial femoral circumflex→inferior gluteal 6. medial femoral circumflex↔obturator 7. lateral femoral circumflex→superior gluteal 8. deep iliac circumflex→superior gluteal 9. deep iliac circumflex→external iliac 10. last lumbar→superior gluteal 11. last lumbar→deep iliac circumflex 12. iliolumbar→deep iliac circumflex. additional images iliolumbar artery