accessory hemiazygous vein (anatomy)

Last reviewed 01/2018

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:

• hemiazygous vein
• left bronchial veins
• left superior intercostal veins

Hence, the accessory hemiazygous vein may drain from:

• the right posterior thoracic cage
• part of the left lung