All of the lymph flows into either the thoracic duct or which structure?

• A. Right lymphatic duct
• B. Left lymphatic duct
• C. Veins near the lungs
• D. Veins near the heart

Answer: (A)

All lymph returns to the bloodstream via two main ducts: the thoracic duct and the right lymphatic duct. The thoracic duct handles lymph from most of the body and drains into the left venous angle (where the left internal jugular and left subclavian veins meet). The right lymphatic duct handles lymph from the right side of the head and neck, right upper limb, and right thorax, draining into the right venous angle (where the right internal jugular and right subclavian veins meet). Because of this arrangement, lymph from the right upper quadrant ultimately enters the circulation through the right lymphatic duct. The other options aren’t the primary return ducts for most lymph.