The lymphatic system is also known as the secondary circulatory system of the body and is closely linked to the blood circulatory system.
The lymph duct refers to the lymphatic vessels which empty the lymph into one of the two subclavian veins- the thoracic duct and the right lymphatic duct.
The right lymphatic duct empties the lymph from the right upper limb, the right side of the thorax and right halves of head and neck.
The thoracic duct is the major lymphatic duct that empties the lymph from the rest of the body and brings it to blood circulation.