Which structure drains lymph from the left chest, abdomen, and lower limbs?

• A. Right lymphatic duct
• B. Lymphatic capillaries
• C. Thoracic duct
• D. Cisterna chyli

Answer: (C)

The thoracic duct is the main lymphatic channel that returns lymph from most of the body below the diaphragm and from the left side above it to the venous system. It collects lymph from the abdomen, pelvis, lower limbs, and the left chest (along with the left side of the head and neck and left upper limb) and empties into the venous circulation at the junction of the left subclavian and internal jugular veins. The cisterna chyli is a dilated sac at roughly the L1–L2 level that gathers lymph from the lower body and the intestinal trunk and serves as the origin of the thoracic duct. The right lymphatic duct handles lymph from the right side of the head, neck, thorax, and right upper limb, not the regions described. Lymphatic capillaries are the tiny vessels that begin the drainage process by absorbing interstitial fluid, but they are not the single drainage pathway for these areas.