184 ELEMENTS OF MAMMALIAN ANATOMY 



All parts of the body have communication with the lym- 

 phatic vessels, which for the most part are so small as to be 

 invisible unless injected, when they are easily recognized by 

 their beaded appearance caused by the numerous valves within 

 them. There are two systems of vessels in the head and 

 extremities — the superficial and the deep. The former accom- 

 pany mainly the superficial veins, and the latter follow the 

 deep veins. On the outer aspect of the thoracic limb just 

 beneath the skin two vessels are present, which flow into the 

 cervical glands. They carry the lymph from the ball of the 

 foot and the skin of the foot and forearm. One or two deep 

 lymph-vessels are found accompanying the brachial vein and 

 artery, which convey the lymph from the bones and muscles 

 of the arm to the axillary gland. 



In the pelvic limb two or three superficial vessels are pres- 

 ent transmitting the lymph from the foot of the popliteal 

 gland, whence two vessels proceed to the deep lymphatic sys- 

 tem. The lymph from the bones and muscles of the leg 

 reaches the iliac glands through two or three deep vessels lying 

 near the femoral vein and artery. The inguinal glands receive 

 most of the lymph from the skin of the leg. 



The lymph from the superficial parts of the head flows 

 largely into the submaxillary lymph glands, while that from 

 the brain, tongue, esophagus, and larynx empties into the 

 laryngeal glands. 



The lymph of the right forelimb, right side of the neck and 

 head, and right side of the thoracic wall is received by the 

 right tracheal trunk. The left tracheal trunk receives the 

 lymph from the left side of the head, neck and thoracic wall, 

 and the left forelimb. The thoracic duct receives the lymph 

 from the lungs, heart, all the abdominal viscera, and muscles, 

 and the hind-limbs. With but few exceptions, all the main- 

 lymphatic vessels pass through lymphatic glands before reach- 

 ing one of the three main trunks. In fact, the vessels bring- 

 ing the lymph to the glands may be said to terminate there. 



