560 



LYMPHATICS. 



prolongations dip into its substance forming partitions. The lymphatic and 

 lacteal vessels pass through these bodies in their passage to the thoracic and 

 lymphatic ducts. A lymphatic or lacteal vessel, previous to 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 coat and 

 epithelium, pass into the gland, where they subdivide and pursue a tortuous 



course ; and they finally anasto- 

 Fig. 314. The Thoracic and Right Lymphatic Duct. 



mosej so as to f orm a p l exus> 

 vessels composing this plexus 

 unite to form two or more efferent 

 vessels, which, on emerging from 

 the gland, are again invested with 

 their external coat. Further de- 

 tails on the minute anatomy of 

 the lymphatic vessels and glands 

 will be found in the Introduction. 



THOBACIC DUCT. 



The Thoracic Duct (Fig. 314) 

 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 thorax, and 

 right upper extremity, 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 recep- 

 taculum chyli (reservoir or cistern 

 of Pecquet), which is situated up- 

 on 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 Diaphragm, and 

 is placed in the posterior medias- 

 tinum in front of the vertebral 

 column lying between the aorta 

 and vena azygos. Opposite the 

 fourth dorsal vertebra, it inclines 

 towards the left side and ascends 

 behind the arch of the aorta, on 

 the left side of the oesophagus, 

 and behind the first portion of the 

 left subclavian artery, to the 

 upper orifice of the thorax. Op- 

 posite the upper border of the 



