[TA] formed by the merger of the left ascending lumbar vein with the left subcostal vein or a communication from the inferior vena cava, it pierces the left crus of the diaphragm, ascends along the left side of the bodies of the lower thoracic vertebrae, opposite the eighth vertebra, crosses the midline posterior to the aorta, thoracic duct, and esophagus, and empties into the azygos vein, sometimes in common with the accessory hemiazygos vein. SYN: vena hemiazygos [TA], inferior hemiazygos vein, vena azygos minor inferior.