Intercostal veins

The intercostal veins are a group of veins which drain the areas between the ribs ("costae"), called the intercostal spaces.

The right posterior intercostal veins drain into the azygos vein. The left posterior intercostal veins drain into the hemiazygos and accessory hemiazygos venous system.

The anterior intercostal veins drain into the internal thoracic and musculophrenic veins on their respective sides.