What is "posterior cardinal vein"

n. a major drainage channel from the caudal part of the body

The postcardinal veins or posterior cardinal veins join with the corresponding right and left cardinal veins to form the left common cardinal veins, which empty in the sinus venosus. Most of the posterior cardinal veins regress, what remains of them forms the renal segment of the inferior vena cava and the common iliac veins. Later in the development stages, the posterior cardinal veins are replaced by the subcardinal and supracardinal veins. The subcardinal veins form part of the inferior vena cava, renal veins and gonadal veins. The supracardinal veins form part of the inferior vena cava, the intercostal veins, hemiazygos vein and azygos vein.