360 



THORACIC DUCT. 



Fig. 167 * 



The thoracic duct presents fewer valves iu 

 its course than lymphatic vessels generally ; at 

 its termination it is provided with a pair of 

 semilunar valves, which prevent the admission 

 of venous blood into its cylinder. 



Branches. The thoracic duct receives at 

 its commencement four or five large lymphatic 

 trunks, which unite to form the receptaculum 

 chyli : it next receives the trunks of the lacteal 

 vessels. Within the thorax it is joined by a 

 large lymphatic trunk from the liver, and in 

 its course through the posterior mediastinum, 

 receives the lymphatic 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 vessels 

 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 terminates at the junction of the ri^ht 

 subclavian with the right internal jugular vein, 

 at the point where these veins unite to form 

 the right vena innominata. It is provided at 

 its termination with a pair of semilunar valves, 

 which prevent the entrance of blood from the 

 veins. 



* 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 sub- 

 clavian arteries. 5. The left carotid. 6. The left subclavian. 7. The superior cava, 

 formed by the union of 8, the two venae innominatae; 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 lymphatic trunks are seen opening into it. 13. The thoracic duct, divid- 

 ing opposite 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 posterior aspect of the junc- 

 tion of the internal jugular and subclavian vein. 15. The termination of the trunk of 

 Uie ductus lymphaticus dexter. 



