OF THE THORAX. 637 



and left innominate vein ; this group consists of numerous large glands. They 

 receive the lymph from the pericardium, heart, and thymus gland. 



The lymphatic vessels of the lung consist of two sets, superficial and deep : 

 the former are placed beneath the pleura, forming a minute plexus which covers 

 the outer surface of the lung ; the latter accompany the blood-vessels and run along 

 the bronchi : they both terminate at the root of the lungs in the bronchial glands. 

 The efferent vessels from these glands, two or three in number, ascend upon the 

 trachea to the root of the neck, traverse the tracheal and oesophageal glands, and 

 terminate on the left side in the thoracic duct and on the right side in the right 

 lymphatic duct. 



The cardiac lymphatic vessels consist of two sets, superficial and deep : the 

 former arise in the subserous areolar tissue of the surface, and the latter in the 

 deeper tissues of the heart. They follow the course of the coronary vessels : those 

 of the right side unite into a trunk at the root of the aorta, which, ascending across 

 the arch of that vessel, communicates with one or more of the cardiac glands, and 

 passes backward to the trachea, upon which it ascends, to terminate at the root of 

 the neck in the right lymphatic duct. Those of the left side unite into a single 

 vessel at the base of the heart, which, passing along the pulmonary artery and 

 traversing some glands at the root of the aorta, ascends on the trachea to terminate 

 in the thoracic duct. 



The thymic lymphatic vessels arise from the under surface of the thymus gland, 

 and enter the superior mediastinal glands, from which they emerge as two vessels : 

 these terminate, one on each side, in the corresponding internal jugular vein. 



The lymphatic vessels of the oesophagus form a plexus round that tube, traverse 

 the glands in the posterior mediastinum, and, after communicating with the 

 pulmonary lymphatic vessels near the roots of the lungs, terminate in the thoracic 

 duct. 



