drains drains posterior region of body posterior vena cava http://upload.wikimedia.org/wikipedia/commons/4/4d/Gray577.png inferior caval vein vena cava inferior GAID:548 AAO:0011083 XAO:0000388 inferior vena cava MA:0000480 VHOG:0001194 BTO:0002682 caudal vena cava NCIT:C12815 MESH:D014682 FMA:10951 Trunk of systemic vein which is formed by the union of the right common iliac vein and the left common iliac vein and terminates in the right atrium[FMA]. Wikipedia:Inferior_vena_cava EMAPA:18416 galen:InferiorVenaCava UMLS:C0042458 postcava SCTID:181369003 Phylogenetic modifications within this basic pattern of arteries and veins are largely correlated with functional changes. In the transition from water to land, gills gave way to lungs, accompanied by the establishment of a pulmonary circulation. In some fishes and certainly in tetrapods, the cardinal veins become less involved in blood return. Instead, the composite, prominent postcava (posterior vena cava) arose to drain the posterior part of the body and the precava (anterior vena cava) developed to drain the anterior part of the body.[well established][VHOG] uberon UBERON:0001072 EHDAA2:0000611 A vein that carries deoxygenated blood from the lower half of the body into the right atrium of the heart. posterior vena cava anterior vena cava vena cava