THORACIC DUCTS 311 



some more direct means of getting into the general circulation. 

 For example, he has found several large lymphatic trunks 

 emptying into the ascending cava, one of them opposite the 

 third lumbar vertebra ; another into the primitive iliac veiiy he 

 has also found some of the lymphatics of the liver discharging 

 into the vena portarum. 



The Right Thoracic Duct, (Ductus Thoracicus Dexter,) as it 

 is called, but more properly the Right Brachio-cephalic, after 

 the name given by M. Chaussier to the vein, is not more than 

 an inch long, and descends to empty itself, as mentioned, into 

 the junction of the right internal jugular with the right subcla- 

 vian vein. It is derived from the lymphatic trunks of the right 

 side of the head and neck, from the right upper extremity, the 

 superficial lymphatics of the right side of the thorax, the lympha- 

 tics of the right lung, of the right side of the diaphragm, and 

 some of those of the right side of the liver, the courses of all of 

 which have been detailed. 



Though the single trunk is formed from these several tributary 

 streams, yet the latter have sometimes several embouchures into 

 the venous system at or near the point mentioned, and, as on 

 the other side of the body, there is a proper security, by valves, 

 from the introduction of blood into them. 



There is always an ample system of anastomosis, not only 

 between the branches which concur to form the right and left 

 thoracic ducts, but even between the ducts themselves,* so that 

 if one be occluded or impeded, its circulation can be turned 

 into the other, as in the case of veins. 



* Meckel, Man, D'Anat, torn, ii, p, 581. 



