Into which vein does the Thoracic Duct drain?

• A. Left subclavian vein
• B. Right subclavian vein
• C. Internal jugular vein
• D. Superior vena cava

Answer: (A)

The lymph from the thoracic duct returns to the bloodstream at the left venous angle, the junction of the left internal jugular and left subclavian veins. In practice, this means the thoracic duct drains into the left subclavian vein at or near its meeting point with the left internal jugular vein. The right lymphatic duct handles drainage on the right side, so the right subclavian vein isn’t the correct site for the thoracic duct. Draining into the internal jugular vein alone isn’t exact, since the duct empties at the junction of both vessels on the left. The superior vena cava is a bigger venous conduit, but the lymphatics return to circulation before that point, at the left venous angle.