The right lymphatic duct and thoracic duct are the large collecting ducts. The right lymphatic duct drains the right side of the head, right upper limb, right thorax and lung, right side of the heart, and the upper portion of the liver. The contents of the right lymphatic duct drain into the right subclavian vein and are returned to the blood. The thoracic duct, the largest collecting duct, receives lymph from the three-quarters of the body including the left side of the head, neck, chest, the left upper limb, and the entire body below the ribs. It drains into the left subclavian vein.