730 THE LYMPHATIC SYSTEM 



and thence to the broncho-mediastinal trunk. A superficial set arises in a network 

 situated upon the surface of the lung beneath the visceral layer of the pleura. 



According to IMiller, who has studied the lymphatics of lung and pleura most carefully in 

 dog and man, the only communications between the lymphatics of the pleura and the deep lym- 

 phatics occur around the veins which reach the pleural surface. These vessels are provided 

 with valves so that the lymph stream passes, in them, toward the pleural surface. The collect- 

 ing stems of the subpleural lymphatics pass independently to the pulmonary nodes. 



Lymphatics of the heart. — The superficial (subepicardial) lymphatics of the 

 heart collect to two main stems which accompany the main coronary vessels. 

 The right stem accompanies the right coronary artery to its origin, passes on 

 over the arch of the aorta and empties into one of the anterior mediastinal lymph- 

 nodes. The left stem, formed by two stems accompanying the circumflex and 

 anterior descending branches of the coronary vein, passes behind the arch of the 

 aorta to an anterior mediastinal lymph-gland. Two small subepicardial inter- 

 calated nodes have been described along these trunks. 



Subendocardial lymphatics have been described in animals, which connect 

 by vessels passing through the musculature with the superficial lymphatics. 



Parenchymatous lymphatics have recently been demonstrated by Bock. 

 The course of their efferent vessels has not yet been described. 



The lymphatic vessels of the oesophagus, which will here be considered 

 throughout its entire extent, cervical as well as thoracic, are arranged in two 

 plexuses, one of which occurs in the mucosa and the other in the submucosa. The 

 collecting vessels arising from the plexuses may be divided into three sets, of 

 which the uppermost pass to outlying nodes belonging to the deep cervical chain, 

 those from the thoracic portion of the tube pass to the bronchial and posterior 

 mediastinal nodes, while those from its lowermost part pass to the superior gastric 

 nodes (fig. 573). 



D. THE LYMPHATICS OF THE ABDOMEN AND PELVIS 



In the following section there will be described successively the lymphatic 

 nodes of the abdomen and pelvis, the lymphatic vessels of the abdominal walls, 

 and the visceral lymphatic vessels. 



1. The Lymphatic Nodes of the Abdomen and Pelvis 



The lymphatics which connect directly with the thoracic duct, though 

 complicated, may be described briefly by saying that they follow the aorta and its 

 branches. In the abdomen there are four main chains along the aorta — (1) the 

 left lumbar chain; (2) the right lumbar chain; (3) the pre-aortic chain; and (4) 

 the post-aortic chain. 



The right and left lumbar nodes [Igl. lumbales], form an almost continuous 

 chain along the abdominal aorta, resting upon the psoas muscles, some of those 

 on the right side being ventral and some dorsal to the inferior vena cava. They 

 receive: — (1) the efferent lymphatics of the common iliac nodes, and hence drain 

 the leg and external genitalia; (2) the efferent lymphatics that follow the lumbar 

 arteries and hence drain the abdominal wall; (3) the efferents that follow the 

 paired visceral aortic branches, namely, those from the kidneys, supra-renal, and 

 internal reproductive organs. On the right side, the lymphatics from the re- 

 productive organs pass to the nodes ventral to the vena cava — those of the 

 abdominal walls pass to the dorsal set, while those from the kidney pass to both 

 sets. 



The efferent vessels of the lower lumlmr nodes pass to higher ones and so on up 

 the chain, the vessels from the uppermost nodes uniting to form a single lumbar 

 trunk on each side. These trunks pass to the thoracic duct, forming two of the 

 so-called trunks of origin of that vessel (fig. 571). 



'J'he pre-aortic nodes [lymphoglandulaj ccrliaca^] are arranged in three groups 

 at the root of each of the three unpaired visceral branches of the aorta — the 

 cfpliac, the superior mesenteric, and the inferior mesenteric arteries. The 

 coeliac nodes are from one to three in number, and are in reality parts of chains of 

 nodes oxt(;nding along tlie branches of the artery and constituting the hepatic, 

 gastric, and splenic nodes. 'J'hey drain the stomach, duodenum, liver, pancreas, 

 and spleen. 



