296 THE VASCULAR SYSTEMS 



The cystic vein drains the gall-bladder and accompanies the 

 gall-duct to open into the right branch of the portal vein. 



The parumbilical veins are small veins found in the urachus 

 and ligamentum teres, which establish an anastomosis between 

 the anterior abdominal wall and the portal and iliac veins. 

 They are best seen from the umbilicus upward, running along 

 the round ligament, then between the layers of the falciform 

 ligament, to end in the left branch of the portal vein. 



THE ABSORBENT OR LYMPHATIC SYSTEM 



The absorbent system consists of vessels resembling thin- 

 walled veins, the lymphatics, interrupted at intervals by the 

 lymphatic nodes. The lymphatics of the alimentary canal 

 are called lacteals. All these vessels converge to two principal 

 trunks, the thoracic duct and the right h/m])h(itir dud, which 

 open into the large veins at the root of the neck. 



The Thoracic Duct 



The thoracic duct is the common trunk of all the lymphatic 

 vessels of the body, excepting those which drain the right 

 side of the head and neck, the right upper extremity, the right 

 lung, right side of the heart, and part of the convex surface 

 of the liver. It is from 15 to IS inches in length, in the adult, 

 and begins as the receptaculum chyli. The duct extends from 

 the second lumbar vertebra to the root of the neck, where it 

 empties into the angle of junction of the left internal jugular and 

 subclavian veins. It is placed in front of the dorsal vertebra? 

 and passes to the thorax through the aortic opening between the 

 aorta and vena azygos major. It then runs upward toward the 

 left, behind the arch of the aorta (at the fourth dorsal vertebra), 

 then between the esophagus and left subclavian artery, and 

 at the seventh cervical vertebra it arches over the pleura to 

 join the angle of union between the left subclavian and internal 

 jugular veins. 



The right lymphatic duct collects the lymph from the parts 

 just mentioned above. It is only one-half inch or less in length, 

 and empties on the right side, at a point corresponding to that 

 where the thoracic duct empties on the left side. 



