The lymphatic system consists of lymph nodes (or lymph glands) and lymphatics (the small vessels that link the lymph nodes). It returns excess fluid to the circulation and helps fight infection and cancer. The lymph nodes (which generally occur in clusters in the neck, armpits, and groin) produce some white blood cells and antibodies that help protect against infection. The right lymphatic duct and the thoracic duct drain lymph fluids into 2 veins that come together to form the superior vena cava, which passes into the heart. The cisterna chyli is a widened portion of the thoracic duct, where fluids from several lymph-collecting vessels are received. The spleen removes and destroys worn-out red blood cells and helps fight infection.
