692 THE LYMPHATICS. 



receiving lymphatics from the intercostal muscles and pleura ; they pass backward 

 to the spine, and unite with lymphatics from the back part of the thorax and spinal 

 canal. After traversing the intercostal glands, they pass down the spine and 

 terminate in the thoracic duct. 



The internal mammary lymphatic vessels follow the course of the internal 

 mammary vessels ; they commence in the muscles of the abdomen above the 

 umbilicus, communicating with the epigastric lymphatics, ascend between the 

 fibres of the Diaphragm at its attachment to the ensiform appendix, and in their 

 course behind the costal cartilages are joined by the intercostal lymphatics; they 

 terminate on the righ^ side in the right lymphatic duct, on the left side in the 

 thoracic duct. 



The lymphatic vessels of the Diaphragm follow the course of their correspond- 

 ing vessels, and terminate, some in front in the anterior mediastinal and internal 

 mammary glands, some behind, in the intercostal and posterior mediastinal lymph- 

 atics. 



The Lymphatic Glands of the Viscera are the bronchial glands. 



The bronchial glands are situated round the bifurcation of the trachea and 

 roots of the lungs. They are ten or twelve in number, the largest being placed 

 opposite the bifurcation of the trachea, the smallest round the bronchi and their 

 primary divisions for some little distance within the substance of the lungs. In 

 infancy they present the same appearance as lymphatic glands in other situations ; 

 in the adult they assume a brownish tinge, and in old age a deep black color. 

 Occasionally they become sufficiently enlarged to compress and narrow the canal 

 of the bronchi, and they are often the seat of tubercle or cretaceous deposits. 



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, 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 terminate on each side in the internal jugular veins. 



The thyroid lymphatic vessels arise from either lateral lobe of this organ : they 

 converge to form a short trunk, which terminates on the right side in the right 

 lymphatic duct, on the left side in the thoracic duct. 



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, 



