intercostal veins intercostal veins the intercostal veins are a group of veins which drain the area between the ribs ("costae"), called the intercostal space. intercostal veinsintercostal spaces, viewed from the left.detailsdrains fromintercostal muscle, intercostal spacearteryintercostal arteriesidentifierslatinvenae intercostalesanatomical terminology they can be divided as follows: anterior intercostal veins posterior intercostal veins posterior intercost vein that drain into the supreme intercostal vein - 1st intercostal space posterior intercost veins that drain into the superior intercostal vein - 2nd, 3rd, and 4th intercostal spaces. the superior intercostal vein then drains into the azygous vein. posterior intercost veins that drain directly into the azygous vein - in spaces 5-11. subcostal vein -- below bottom (12th) rib and also drains into the azygous vein.