What is Thoracic duct?
Thoracic duct meaning The thoracic duct is one of the main lymphatic trunks. The lymphatic capillaries originate as microscopic blind-end vessels which are located in the intercellular spaces and are widely distributed throughout the body. Small lymphatics merge with larger ones and they, in turn, with still larger vessels until they join (much like the branches of a tree) to form the main lymphatic trunks: the right lymphatic duct and the thoracic duct. Lymph from the entire body, except the right upper quadrant, drains eventually into the thoracic duct which flows into the subclavian vein at the point where it joins the left internal jugular vein. Lymph from the upper right quadrant of the body empties into the right subclavian vein by way of the right lymphatic duct. Since most of the body lymph returns to the bloodstream via the thoracic duct, this vessel is much larger than the right lymphatic duct-but it is much smaller than the large veins which it resembles in structure. The thoracic duct varies in length from 35 to 48 cm. It originates as a dilated structure, the cisterna chyli, in the lumbar region of the abdominal cavity, and ascends by a winding course to the root of the neck where it joins the left subclavian vein.