The accessory hemiazygous vein is the venous confluence of the right posterior fourth to eighth intercostal veins. It forms a vessel parallel and lateral to the vertebral bodies of T4 to T8. At T8 or T9 it passes medially to merge with the azygous vein posterior to the oesophagus and thoracic duct.
The accessory hemiazygous vein may also receive tributaries from the:
Hence, the accessory hemiazygous vein may drain from:
Last reviewed 01/2018