Trunk vessels (aorta, vena cava, abdominal branches)
Azygos vein
Vena azygos
- Origin
- Formed at the T12/L1 junction by the confluence of the right subcostal vein and right ascending lumbar vein
- Insertion
- Ascends in the posterior mediastinum on the right side of the vertebral column, arches anteriorly over the right lung root at T4 (arch of azygos) to enter the SVC
- Function
- Drains the posterior thoracic wall, bronchi, esophagus, and pericardium; receives the hemiazygos and accessory hemiazygos veins
- Innervation
- Thoracic sympathetic vasomotor fibers
- Movement & chain
- Continuous systemic venous return
- Palpation
- Not palpated directly
- Clinical
- Primary cavo-caval collateral channel in IVC or SVC obstruction; azygos lobe (fissure caused by aberrant descent of the azygos vein into the right upper lung lobe).
- Segmental innervation
- T4-T12 levels
- In clinical practice
- Evaluation of azygos enlargement (>10 mm) on upright CXR indicating elevated central venous pressure or IVC obstruction
- Region in the model
- Trunk vessels (aorta, vena cava, abdominal branches)