THORACIC DUCT. 



483 



THORACIC DUCT. 



The Thoracic Duct (fig. 247) conveys the great mass of the 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 Kg- 247.-The Thoracic and Right Lymphatic Ducts. 



thorax, and right upper ex- 

 tremity, the right lung, right 

 side of the heart, and the 

 convex surface of the liver. 

 It varies from eighteen to 

 twenty inches in length in 

 the adult, and extends from 

 the second lumbar vertebra 

 to the root of the neck. It 

 commences in the abdomen 

 by a triangular dilatation, the 

 receptaculum chyli (reservoir 

 or cistern of Pecquet), which 

 is situated upon the front of 

 the body of the second lumbar 

 vertebra, to the right side of 

 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 Diaphragm, 

 and is placed in the posterior 

 mediastinum in front of the 

 vertebral column, lying be- 

 tween the aorta and vena 

 azygos. Opposite the fourth 

 dorsal vertebra it inclines to- 

 wards the left side and ascends 

 behind the arch of the aorta, 

 on the left side of the oeso- 

 phagus, and behind the first 

 portion of the left subclavian 

 artery, to the upper orifice of 

 the thorax. Opposite the 

 upper border of the seventh 

 cervical vertebra it curves 

 downwards above the sub- 

 clavian artery, and in front 

 of the Scalenus muscle, so as 

 to form an arch ; and ter- 

 minates near the angle of 

 junction of the left internal 

 jugular and subclavian veins. 

 The thoracic duct, at its com- 

 mencement, is about equal in 

 size to the diameter of a goose- 

 quill, diminishes considerably 

 in its calibre in the middle 



of the thorax, and is again dilated just before its termination. It is generally 

 flexuous in its course, and constricted at intervals so as to present a varicose 



