hemiazygous vein

The hemiazygous vein is part of the azygous system, which connects the superior and inferior vena cava. This system drains blood from the back and the walls of the chest and abdomen, running alongside the vertebral bodies. The hemiazygous vein, along with the azygous and accessory hemiazygous veins, forms this crucial connection.1

Typically, the hemiazygous vein originates below the diaphragm as a continuation of the left ascending lumbar vein. It then empties into the azygous vein. Its tributaries drain the intercostal muscles, esophagus, and parts of the mediastinum. The accessory hemiazygous vein usually continues downward from the vein of the fourth intercostal space, receiving blood from the left intercostal spaces and the left bronchus before entering the azygous vein just above the hemiazygous vein. The right azygous vein is simply the azygous vein located on the right side of the vertebral column.12