Explanation

The lymphatic ducts of left side unite to form a thoracic duct. This duct begins at the cistern chyli, which is sac-dilation situated in front of the first and second lumbar vertebrae. The thoracic duct has several valves. It discharges its lymph into the left subclavian vein. The lymphatic ducts of right side unite to form right thoracic duct, which discharge its lymph into the right subclavian vein.