accessory hemiazygos vein accessory hemiazygos vein /əkˈsɛsəri hɪˈmeɪəˌzaɪɡəs veɪn/

noun

1. A vein formed by the union of the 4th to 7th posterior intercostal veins; empties into the azygos vein  ( accessory hemiazygos vein , accessory hemiazygous vein , vena hemiazygos accessoria )
   a vein formed by the union of the 4th to 7th posterior intercostal veins; empties into the azygos vein