Azygous Vein

• Origin and course
  • Formed by the confluence of the right ascending lumbar vein with the right sub costal vein.
  • It passes superiorly through the aortic aperture and ascends in the posterior mediastinum 
  • At the level of T4, the azygous vein arches over the root of the right lung to drain into the superior vena cava.
• Relationships
  • Posteriorly the inferior eight thoracic vertebrae
  • Anteriorly the esophagus
  • Medially thoracic descending aorta
• Tributaries
  • Hemiazygous
  • Accessory Hemiazygous
  • Right superior intercostal vein
  • Multiple other small veins
• Drains
  • the posterolateral thoracic and abdominal walls
  • parts of the right lung and mediastinum
  • the middle of the esophagus