: The vein descends along the left side of the 4th to 8th thoracic vertebrae. At approximately the level of the 7th or 8th thoracic vertebra (T7-T8) , it crosses the midline to the right, passing posterior to the aorta and esophagus, to drain into the azygos vein. Tributaries : Left 4th to 8th posterior intercostal veins. Left bronchial veins (variable). Some esophageal and mediastinal veins. Anatomical Variants
The azygos system is notoriously highly variable . Common variants include: accessory hemiazygos vein
: In rare cases (1–2%), it may drain directly into the left brachiocephalic vein . : The vein descends along the left side
