Lumbar veins

The lumbar veins are veins running along the inside of the posterior abdominal wall. They are the lumbar equivalent of the posterior intercostal veins of the thorax.

The lumbar veins accompany the four lumbar arteries on each side of the body. Each lumbar vein lies superior to the adjacent lumbar artery (the same arrangement as in the intercostal neurovascular bundles).

The first and second lumbar veins usually join the ascending lumbar vein rather than the inferior vena cava, which then joins the subcostal vein of the same side to form the azygos vein on the right or hemiazygos vein on the left. The third and fourth lumbar veins drain into the inferior vena cava.

The lumbar veins drain the anterior spinal veins.

The third lumbar vein presents a marked transverse tributary draining the abdominal wall. This venous tributary, called the transverse muscular lumbar vein (Lumbar vein of Michmich), emerges from the abdominal parietal wall on the proximal attachment of oblique muscles, 1 cm above the iliac crest, and runs anteriorly to the surface of the quadratus lumborum muscle (as opposed toother muscular branches of lumbar veins that are located posterior to this muscle). The vein of Michmich ends the lumbar vein in the angle formed by psoas muscle and the quadratus lumborum.