624 



THE LYMPHATIC SYSTEM 



Right 



lymphatic 



duct. 



entering a gland, divides into several small branches, which are named afferent 

 vessels. As they enter their external coat becomes continuous with the capsule of 



the gland, and the vessels, much 

 thinned, and consisting only of 

 their internal or endothelial coat, 

 pass into the gland, and branch 

 out upon and in the tissue of the 

 capsule, these branches opening 

 into the lymph-sinuses of the 

 gland. From these sinuses fine 

 branches proceed to form a plex- 

 us, the vessels of which unite to 

 form a single efferent vessel, which, 

 on emerging from the gland, is 

 again invested with an external 

 coat. (Further details on the mi- 

 nute anatomy of the lymphatic ves- 

 sels and glands will be found in the 

 section on General Anatomy.) 



THE THORACIC DUCT. 



The thoracic duct (Fig. 337) 

 conveys the great mass of lymph 

 and chyle into the blood. It is the 

 common trunk of all the lymphatic 

 vessels of the body, excepting those 

 of the right side of the head, neck, 

 and thorax, and right upper ex- 

 tremity, the right lung, right side 

 of the heart, and the convex sur- 

 face of the liver. It varies in 

 length from fifteen to eighteen 

 inches in the adult, and extends 

 from the second lumbar vertebra 

 to the root of the neck. It com- 

 mences in the abdomen by a trian- 

 gular dilatation, the receptaculum 

 chyli (reservoir or cistern of Pec- 

 quet), which is situated upon the 

 front of the body of the second 

 lumbar vertebra, to the right side 

 and behind the aorta, by the side 

 of the right crus of the Diaphragm. 

 It ascends into the thorax through 

 the aortic opening in the Dia- 

 phragm, lying to the right of the 

 aorta, and is placed in the pos- 

 terior mediastinum in front of the 

 vertebral column, lying between 

 the aorta and vena azygos major. 

 Opposite the fourth dorsal ver- 

 tebra it inclines toward the left 



side, and ascends behind the arch of the aorta on the left side of the 

 ossophagus, and behind the first portion of the left subclavian artery, to the 

 upper orifice of the thorax. Opposite the seventh cervical vertebra it turns 

 outward and then curves downward over the subclavian artery and in front of 

 the Scalenus anticus muscle, so as to form an arch, and terminates in the left 



I-'IG. 337. The thoracic and right lymphatic duct. 



