Ascending lumbar vein

The ascending lumbar vein is a vein that runs up through the lumbar region on the side of the vertebral column.

The ascending lumbar vein is a paired structure. It starts at the common iliac veins. It runs superiorly, intersecting with the lumbar veins as it crosses them. It passes behind the psoas major muscle, but in front of the lumbar vertebrae.

When the ascending lumbar vein crosses the subcostal vein, it becomes one of the following: the azygos vein (in the case of the right ascending lumbar vein), the hemiazygos vein (in the case of the left ascending lumbar vein).

Source : Wikipedia