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 vertebraeAnteriorly the esophagus
  • Medially thoracic descending aorta
  Tributaries
  • HemiazygousAccessory HemiazygousRight superior intercostal vein
  • Multiple other small veins
  Drains
  • the posterolateral thoracic and abdominal wallsparts of the right lung and mediastinum
  • the middle of the esophagus
• Appearance in 
  • CXR in a patient with dilated Azygous vein
  • Venogram  in a patient with dilated Azygous vein