Thoracic duct

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In human anatomy, the thoracic duct, is an important part of the lymphatic system—it is the largest lymphatic vessel in the body. It collects most of the lymph in the body (except that from the right arm and the right side of the chest, neck and head, which is collected by the right lymphatic duct) and drains into the systemic (blood) circulation.

It is also known under various other names including the ductus thoracicus, alimentary duct, chyliferous duct, duct of Pecquet, the left lymphatic duct and Van Hoorne's canal. [1]

In adults, the thoracic duct is typically 38-45cm in length. It usually starts from the level of the second lumbar vertebra and extends to the neck.

It originates in the abdomen from the confluence of various abdominal lymph vessels. It extends vertically in the chest and curves posteriorly to the left carotid artery and left jugular vein to empty into the junction of the left subclavian vein and left jugular vein, near the shoulders. It traverses the diaphragm at the aortic aperture and ascends the posterior mediastinum between the descending thoracic aorta (to its left) and the azygos vein (to its right).

In an adult, the thoracic duct transports up to 4 L of lymph per day. When the thoracic duct is blocked or damaged a large amount of lymph can quickly accumulate in the pleural cavity, this situation is called chylothorax.

The first sign of a malignancy (especially an intraabdominal one) may be an enlarged Virchow's node, a lymph node in the left supraclavicular area, in the vicinity where the thoracic duct empies into the left subclavian vein.

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