The largest lymphatic vessel in the body (with a 5-8 mm gauge) and the most important pathway draining the lymph into the venous bloodstream. It originates from the confluence of the intestinal lymphatic trunk and right and left lymphatic lumbar trunks at the level of the first-second lumbar vertebra. In its initial portion, it may feature an ampulla-shaped dilation called chylous cyst or receptaculum chyli of Pecquet (see). After running posteriorly to the esophagus for about 35-45 cm, between the azygos vein (on the right) and the aorta (on the left), it empties into the left subclavian vein at the level of the homolateral subclavian-jugular angle. In its final portion, the thoracic duct runs to form an anterolateral, concave arch, branching out in different ways.