452 



AXGIOLOGY. 



have a right and left, or double at its origin only ; or it may be 

 single at its origin, then bifid for a short distance, again forming 

 a single trunk ; it contains a few valves. 



The lymphatics, which form the affluents of the thoracic duct, 

 may be divided into five groups, comprised within the following 

 divisions of the body : — 



Posterior region. 

 Digestive viscera. 



Thoracic viscera. 

 Thoracic walls. 



Anterior region. 



Fio. 170. 

 Thorax laid open ou the right side— the lungs being removed. 1, Part of posterior aorta ; 

 2, Trachea divided ; a a, Kight and left branches of origin of thoracic duct (double posteriorly in 

 this instanre) ; h, Point of union of the branches ; c c, Loops leaving and rejoining the duct ; 

 d, Point of discharge of the duct ; e. Cervical lymphatic vessel ; e'. Its termination in the duct. 



POSTERIOR REGION. 



This embraces the lymphatics of the posterior extremity, pelvis, 

 abdominal walls, and organs of the pelvic region. They all 

 converge to a large group of glands, the sublumbar, presenting, 

 however, at different parts of their passage, other groups. We 

 note the following : — 

 Sublumhar. 



Deep inguinal. 

 Superficial inguinal. 



Popliteal. 



Iliac. 



Precrural. 



The sublumbar glands occupy the sublumbar region, resting 

 in the angle formed by the bifurcation of the posterior aorta» 



