THORACIC DUCT. 



397 



phatic vessels generally ; Fig. 137. 



at its termination it is pro- 

 vided with a pair of semi- 

 lunar valves, which prevent 

 the admission of venous 

 blood into its cylinder. 



Branches. The thoracic 

 duct receives at its com- 

 mencement four or five large 

 lymphatic trunks, which 

 unite to form the recepta- 

 culum chyli: it next re- 

 ceives the trunks of the 

 kcteal vessels. Within the 



lymphatic trunk from the 

 liver, and in its course 

 through the posterior me- 

 diastinum, receives the lym- 

 phatic vessels both from the 

 viscera and from the parietes 

 of the thorax. At its curve 

 forwards in the neck it is 

 joined by the lymphatic 

 trunks from the left side 

 of the head and neck, left 

 upper extremity, and from 

 the upper part of the thorax, 

 and thoracic viscera. 



The Ductus lymphaticus 

 dexter is a short trunk which 

 receives the lymphatic ves- 

 sels from the right side of 

 the head and neck, right 

 upper extremity, right side 

 of the thorax, right lung, 

 and one or two branches 

 from the liver, and termi- 

 nates at the junction of the 



* The course and termination of the thoracic duct. 1. The arch of the 

 aorta. 2. The thoracic aorta. 3. The abdominal aorta; shewing its principal 

 branches divided near their origin. 4. The arteria innominata, dividing into 

 the right carotid and right subclavian arteries. 5. The left carotid. 6. The 

 left subclavian. 7. The superior cava, formed by the union of 8, the two vense 

 innominatae ; and these by the junction 9, of the internal jugular and subcla- 

 vian vein at each side. "lO. The greater vena azygos. 11. The termination 

 of the lesser in the greater vena azygos. 12. The receptaculum chyli; several 

 lymphatic trunks are seen opening into it. 13. The thoracic duct, dividing 

 opposite the middle of the dorsal vertebrse into two branches which soon re- 

 unite ; the course of the duct behind the arch of the aorta and left subclavian 



