LYMPHATIC VESSELS. 449 



The buccal or inferior communicating vein resembles the 

 vena varicosa, and is a satellite of the buccal artery ; being the 

 radical of the internal maxillary vein, we have described it with 

 that vessel. 



The sublingual vein is large, consisting of two branches, which 

 unite and pierce the mylo-hyoideus muscle. 



The thyroid vein, a large vessel formed by the laryngeal and 

 thyroid veins, gains the jugular near the termination of the 

 glosso-facial. 



The cephalic vein enters at the inferior extremity of the jugular, 

 coming from the internal superficial vein of the arm ; it is a 

 satellite of the pectoral branch of the inferior cervical artery, and 

 is found in the interstice between the levator humeri and pectoralis 

 anticus muscles. 



The minor branches of the jugular are several nameless ones, 

 which return blood from the parotid gland and cervical muscles. 



LYMPHATIC SYSTEM. 



The lymphatic or absorbent system is connected with the blood- 

 vascular system, and consists of a series of tubes, which absorb 

 and convey to the blood certain fluids ; a number of glandular 

 bodies through which the tubes frequently pass ; and the fluids 

 themselves, which are lymph and chyle. 



LYMPHATIC VESSELS. 



These are called lymphatic vessels, because they convey a clear 

 limpid fluid ; or absorbent vessels, because they absorb aliment- 

 ary matter. The absorbents of the chyle are called lacteal, or 

 chyliferous vessels, but do not differ from the rest in character 

 or anatomical structure. The lymphatics unite to form two 

 large trunks, the thoracic duct, and the right lymphatic vein, 

 both of which enter the venous system near the heart. Delicate 

 in structure, and transparent, they are present in nearly every 

 tissue ; and although more numerous than the blood-vessels, their 

 collective capacity is probably not greater. They are placed 

 superficially and deeply with respect to the more solid organs. 

 The walls of the larger vessels consist of three coats ; the 

 external is composed of a network of interlacing areolar tissue, 

 mixed with fibres of elastic and smooth muscular tissue ; this 

 coat connects the vessel with its surroundings. The middle coat is 



2 G 



