Chest blood vessels. Coloured 3-D magnetic resonance angiography (MRA) scan of the major human chest blood vessels (red). The aortic arch (upper centre) carries oxygenated blood out of the heart and into the descending thoracic aorta (to bottom centre). The two branches of the pulmonary artery (centre left and right) carry deoxygenated blood from the heart to the lungs, where they branch finely. Oxygenated blood drains into the two branches of the pulmonary vein (lower left and right), which return it to the heart. The internal and external jugular veins (black/red, top centre) drain deoxygenated blood into the vena cava (upper left), which returns it to the heart.