Lymphatic ducts drain into which vessels to return lymph to circulation?

• A. Aorta
• B. Pulmonary artery
• C. Jugular vein or vena cava
• D. Superior vena cava

Answer: (C)

Lymph returns to the bloodstream by entering the venous system. The lymphatic ducts (thoracic duct on the left and the right lymphatic duct on the right) drain into veins at the junctions of the jugular and subclavian veins, effectively the venous angles. In practice, that means lymph is returned into veins such as the jugular veins or nearby portions that lead to the cranial vena cava, rather than into arteries like the aorta or pulmonary artery. Since the question asks where lymphatic ducts drain to return lymph to circulation, the best description is into the veins, specifically the jugular vein or the vena cava region.