The thoracic duct carries not only lymph but also chyle which is emptied into the venous system and goes to nourish the body. Therefore a wound of the duct with the escape of its fluid may result fatally from inanition. The lymph coming from all parts of the body is collected into two ducts, the right lymphatic duct and the thoracic duct. Of these two the right lymphatic duct is the smaller. It collects the lymph coming from the right side of the head and neck, right upper extremity, right side of the thorax and the upper convex surface of the liver. The several lymphatic branches unite to form a duct, one to two centimetres long, which empties into the venous system at the junction of the right internal jugular and subclavian veins. At its point of entrance it is guarded by a pair of valves. As this duct contains no chyle, and lymph of only a portion of the body, wounds of it have not proved serious.

The thoracic duct is much larger and more important. It begins on the bodies of the first and second lumbar vertebrae to the right of the aorta in the cisterna (receptaculum) chyli.

The cisterna or receptaculum is 5 to 7.5 cm. long and 7 mm. wide. It receives not only the lymph from the parts below but also the chyle from the intestines. It passes through the aortic opening in the diaphragm with the aorta to the left and the vena azygos major to the right. In the posterior mediastinum it lies on the bodies of the seven lower thoracic vertebrae, with the pericardium, the oesophagus, and the arch of the aorta in front. The thoracic aorta is to its left and the vena azygos major and right pleura to its right. Above the fifth thoracic vertebra it ascends between the oesophagus and left pleura, behind the first portion of the left subclavian artery. On reaching the level of the seventh cervical vertebra it curves downward over the left pleura, subclavian artery, scalenus anticus muscle, and vertebral vein to empty at the junction of the internal jugular and left subclavian veins. It passes behind left internal jugular vein and common carotid artery. At its termination it lies just external to the left sternoclavicular joint and just below the level of the upper border of the clavicle. A punctured wound at this point would injure the duct.

Accompanying the veins of the neck are numerous lymph-nodes which not infrequently become enlarged and require removal. It is in operating on these nodes that wounds of the thoracic duct have been most often produced. When divided, its lumen has appeared to be of the size of a "knitting needle." In some instances the thin walls of the duct have been ligated. In other cases of injury either the oozing point has been clamped with a haemostatic forceps which has been left in position for a day, or else the wound has been packed with gauze. Recovery usually ensues.

Fig. 225.   Dissection of posterior body wall, seen from in front, showing thoracic duct and right lymphatic duct: veins have been laterally displaced to expose the terminations of the thoracic duct. (Piersol).

Fig. 225. - Dissection of posterior body-wall, seen from in front, showing thoracic duct and right lymphatic duct: veins have been laterally displaced to expose the terminations of the thoracic duct. (Piersol).