THE LYMPHATIC SYSTEM 



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subclavian artery and in front of the Scalenus anticus muscle and the phrenic 

 nerve, so as to form an arch; it terminates in the angle of junction of the left 

 subclavian vein with the left internal jugular vein. It usually opens at the apex 

 of the angle in the superior and outer surface, but may open on the posterior 

 surface. Sometimes it terminates by two or more branches. Figs. 552 and 554 

 show the termination of the thoracic duct. The thoracic duct, at its commence- 

 ment, is about 2 to 3 mm. in diameter, diminishes considerably in its caliber in 

 the middle of the thorax, and is again dilated just before its termination, the 

 ampulla. It is generally flexuous in its course, the older the person the greater 

 the flexuosity, and it is constricted at intervals so as to present a varicose appear- 

 ance. The thoracic duct not infrequently divides in the middle of its course into 

 two branches of unequal size, which soon reunite, or divides into several branches, 

 which form a plexiform interlacement. It occasionally divides, at its upper part, 

 into two vessels, of which the one on the left side terminates in the usual manner, 

 while that on the right opens into the right subclavian vein, in connection with the 

 right lymphatic duct. The thoracic duct has several valves throughout its whole 

 course, but they are more numerous in the upper than in the lower part, and the 

 lower valves are not competent; at its termination it is provided with a pair of 

 competent valves, the free borders of which are turned toward the vein, so as to 

 prevent the passage of venous blood into the duct. 



FIG. 553. Modes of origin of the thoracic duct: a. Tnoracic duct. a'. Receptacujum chyli. b,c. Efferent trunks 

 from lateral aortic nodes, d. An efferent passing through the left crus of the diaphragm, e, f. Lateral aortic 

 nodes, g. Preaortic node. h. Retroaortic node. i. Common intestinal trunk, j. Descending tributary from 

 intercostal lymphatics. (Poirier and Charpy.) 



The receptaculum chyli (cisterna chyli} (Figs. 552 and 553) receives the two lumbar 

 Jymphatic trunks, right and left, and the intestinal lymphatic trunk. The lumbar 

 lymphatic trunks (trunci lumbales] are formed by the union of the efferent, vessels 

 from the lateral aortic lymph nodes. They receive the lymph from the lower 

 limbs, from the walls and viscera of the pelvis, from the kidneys and suprarenal 

 bodies, and the deep lymphatics of the greater part of the abdominal wall. The 

 intestinal lymphatic trunk (truncus intestinalis) receives the lymph from the 

 stomach and small intestine, from the pancreas and spleen, and from the lower 

 and front part of the liver. 



Tributaries. Opening into the commencement of the thoracic duct, on either 

 side, is a descending trunk from the posterior intercostal nodes of the lower six 

 or seven intercostal spaces. In the thorax the duct is joined, on either side, by 

 a trunk which drains the upper lumbar nodes and pierces the crus of the Dia- 

 phragm. It also receives the efferents from the posterior mediastinal nodes and 

 from the posterior intercostal nodes of the upper six left spaces. In the neck it 

 is joined by the left jugular and left subclavian trunks, and sometimes by the left 



