THORACIC DUCT. 



361 



Fig. 184 * 



These vessels, as it has been already 

 observed, are derived from various 

 sources, viz. j 



The lower extremities ; the lower 

 part of the trunk of the body ; the 

 organs of generation ; the intestines, 

 with the other viscera of the abdomen 

 and pelvis, except a part of the liver. 

 Their number is proportioned to the 

 extent of their origin : for, with the 

 numerous glands appropriated to 

 them, they form the largest absorbent 

 plexus in the body, and are spread 

 over a considerable portion of the 

 aorta and the vena cava. 



The manner in which these vessels 

 unite to form the thoracic duct, is very 

 different in different subjects; but in 

 a majority of cases it originates imme- 

 diately from three vessels, two of 

 which are the trunks of the absorbents 

 of the lower extremities, and the other 

 is the common trunk of the lacteals 

 and the other absorbents of the intes- 

 tines. 



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

 2. The thoracic aorta. 3. The abdominal aorta ; showing its principal branches 

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

 carotid and right subolavian arteries. 5. The left carotid. 6. The left sub- 

 clavian. 7. The superior cava, formed by the union of 8, the two venae inno- 

 minatse ; and these by the junction 9, of the internal jugular and subclavian 

 vein at each side. 10. The greater vena azygos. 11. The termination of the 

 lesser in the greater vena azygos. 12. The receptaculum chyli several lym- 

 phatic trunks are seen opening into it. 13. The thoracic duct, dividing oppo- 

 site the middle of the dorsal vertebrae into two branches which soon reunite ; 

 the course of the duct behind the arch of the aorta and left subclavian artery 

 is shown by a dotted line. 14. The duct making its turn at the root of the neck 

 and receiving several lymphatic trunks previously to terminating in the poste- 

 rior aspect of the junction of the internal jugular and subclavian vein. 15. 

 The termination of the trunk of the right branchio-cephalic duct. 



VOL. II. 31 



