paired, vertical vein of the posterior abdominal wall, adjacent and parallel to the vertebral column, posterior to the origin of the psoas major muscle; it connects the common iliac, iliolumbar, and lumbar veins in the paravertebral line, the right vein joining the right subcostal vein to form the azygos vein, the left vein uniting with the left subcostal vein to form the hemiazygos vein. Syn: vena lumbalis ascendens [NA].