THE LYMPHATICS OF THE THORAX 805 



The tracheobronchial nodes form three main groups in relation to the bifurca- 

 tion of the trachea one on either side of the trachea above the bronchi and 

 one in the angle between the bronchi (lymphoglandulae tracheales); other nodes, 

 termed interbronchial (lymphoglandulae bronchiales), are found at the points of 

 division of the larger bronchi. The afferents of the tracheobronchial nodes 

 drain the lungs and bronchi, the thoracic part of the trachea and the heart; some 

 of the efferents of the posterior mediastinal nodes also terminate in this group. 

 Their efferent vessels ascend upon the trachea and unite with efferents of the 

 internal mammary and anterior mediastinal nodes to form the right and left 

 broncho mediastinal trunks. The right bronchomediastinal trunk may join the 

 right lymphatic duct, and the left the thoracic duct, but more frequently they 

 open independently of these ducts into the junction of the internal jugular and 

 subclavian veins of their ow r n side. 



Applied Anatomy. In all town dwellers there are continually being swept into those nodes 

 from the bronchi and alveoli large quantities of the dust and black carbonaceous pigment that are 

 so freely inhaled in cities. At first the nodes are moderately enlarged, firm, inky black, and 

 gritty on section; later they enlarge still further, often becoming fibrous from the irritation set 

 up by the minute foreign bodies with which they are crammed, and may break down into a soft 

 slimy mass or may calcify. In tuberculosis of the lungs these nodes are practically always 

 infested; they enlarge, being filled with tuberculous deposits that may soften, or become fibrous, 

 or calcify. Xot infrequently an enlarged tuberculous node perforates into a bronchus, dis- 

 charging its contents into the tube. When this happens there is great danger of acute pul- 

 monary tuberculosis, the infecting node-substance being rapidly spread throughout the bronchial 

 system by the coughing its presence in the air-passages excites. 



The lymphatic vessels of the thoracic viscera consist of those of the heart 

 and pericardium, lungs and pleura, thymus and oesophagus. 



The lymphatic vessels of the heart consist of two plexuses: (a) deep, immediately 

 under the endocardium, and (6) superficial, subjacent to the visceral pericardium. 

 The deep plexus opens into the superficial, the efferents of which form right 

 and left collecting trunks. The left trunks, two or three in number, ascend in 

 the anterior interventricular furrow, receiving, in their course, afferents from both 

 ventricles. On reaching the auriculoventricular furrow they are joined by a large 

 trunk from the back of the heart, and then unite to form a single vessel which 

 descends between the pulmonary artery and the left auricle and ends in one 

 of the tracheobronchial nodes. The right trunk receives its afferents from the 

 right auricle and from the right border and posterior surface of the right ventricle. 

 It ascends in the posterior auriculoventricular groove and then runs forward in 

 the auriculoventricular groove, and passes up behind the pulmonary artery, to 

 end in one of the tracheobronchial nodes. 



The lymphatic vessels of the lungs originate in two plexuses, a superficial and 

 a deep. The superficial plexus is placed beneath the visceral pleura. The deep 

 accompanies the branches of the pulmonary vessels and the ramifications of the 

 bronchi. In the case of the larger bronchi the deep plexus consists of two net- 

 works, one, submucous, beneath the mucous membrane, and another, peribron- 

 chial, outside the walls of the bronchi. In the smaller bronchi there is but a 

 single plexus, which extends as far as the bronchioles, but fails to reach the alveoli, 

 in the walls of which there are no traces of lymphatic vessels. The superficial 

 efferents turn around the borders of the lungs and the margins of their fissures, 

 and converge to end in some nodes situated at the hilum; the deep efferents are 

 conducted to the hilum along the pulmonary vessels and bronchi, and end in the 

 tracheobronchial nodes. Little or no anastomosis occurs between the superficial 

 and deep lymphatics of the lungs, except in the region of the hilus. 



The lymphatic vessels of the pleura consist of two sets one in the visceral 

 and another in the parietal part of the membrane. Those of the visceral pleura 



