Thoracic duct
Ductus thoracicus
Lymphatic & immuneLymphaticsWhole body
- What it is
- The largest lymph vessel in the body. It begins at the cisterna chyli, passes up through the aortic opening of the diaphragm, climbs the back of the chest between the aorta and the azygos vein, crosses from right to left behind the oesophagus at the level of T4-T6, arches over the top of the left lung at the root of the neck and empties into the junction of the left internal jugular and subclavian veins.
- Function
- Returns 2-4 litres of lymph a day, from everything except the right arm and right side of the head and chest, back into the bloodstream.
- Size
- About 38-45 cm long, 3-5 mm in diameter, with valves along its length and at its mouth
- Clinical note
- Tearing it during chest surgery or by a penetrating injury fills the pleural space with milky chyle (chylothorax), which can drain litres a day and starve the patient of fat and lymphocytes.