The ilio-lumbar artery (ilio-lumbalis, — Haller), resembles in a great measure the lumbar arteries.
It passes outwards beneath the psoas muscle and external iliac vessels, to reach the margin of the iliac fossa, where it divides into two principal branches. One of these, the lumbar branch, passes upwards, ramifying in the psoas and quadratus muscles, communicating with the last lumbar artery; it also furnishes small vessels which enter the intervertebral foramina, and supply the parts lodged in the vertebral canal. The other branch or iliac portion of the artery turns downwards and outwards, either in the substance of the iliacus muscle, or between it and the surface of the ilium. Some of its branches reach the crest and spine of that bone, where they anastomose with the circumflex iliac artery, and may be traced forwards through the abdominal muscles, which they supply, and in which they communicate with the external branches of the epigastric artery.
The ilio-ltimbar artery, as already mentioned, sometimes arises from the internal iliac, above the division of that trunk. It has also been found to spring from the common iliac, but this latter peculiarity is rare. The iliac and lumbar portions of the ilio-lumbar artery sometimes arise separately from the parent trunk.
When the lowest of the lumbar arteries is wanting, the ilio-lumbar is increased in size, and, with a small offset of the middle sacral artery, supplies its place.