Trunk anatomy in 3D:
veins

The venous system of the trunk, including the superior and inferior venae cavae and the azygos system.

The azygos, hemiazygos and accessory hemiazygos veins drain the posterior thoracic and abdominal walls into the superior vena cava. The hepatic portal vein, formed by the superior mesenteric and splenic veins, carries blood from the digestive organs to the liver before it reaches the inferior vena cava.