O.F THE THORAX. 691 



blood-vessels, passing through a series of small glands, and, after receiving the 

 lymphatics from the pancreas, ultimately pass into the thoracic duct. 



THE LYMPHATIC SYSTEM OF THE INTESTINES. 



The lymphatic glands of the small intestine are placed between the layers of 

 the mesentery, occupying the meshes formed by the superior mesenteric vessels, 

 and hence called mesenteric glands. They vary in number from a hundred to a 

 hundred and fifty, and in size from that of a pea to that of a small almond. 

 These glands are most numerous, and largest above, near the duodenum, and 

 below, opposite the termination of the ileum in the colon. This latter group 

 becomes enlarged and infiltrated with deposit in cases of fever accompanied with 

 ulceration of the intestine*. 



The lymphatic glands of the large intestine are much less numerous than the 

 mesenteric glands ; they are situated along the vascular arches formed by the 

 arteries previous to their distribution, and even sometimes upon the intestine 

 itself. They are fewest in number along the transverse colon, where they form 

 an uninterrupted chain with the mesenteric glands. 



The lymphatic vessels of the small intestine are called lacteals, from the milk- 

 white fluid they usually contain : they consist of two sets, superficial and deep, 

 the former lie between the layers of the muscular coat and between the muscular 

 and peritoneal coats, taking a longitudinal course along the outer side of the 

 intestine : the latter occupy the submucous tissue, and course transversely round 

 the intestine, accompanied by the branches of the mesenteric vessels; they pass 

 between the layers of the mesentery, enter the mesenteric glands, and finally 

 unite to form two or three large trunks which terminate in the thoracic duct. 



The lymphatic vessels of the large intestine consist of two sets : those of the 

 caecum, ascending and transverse colon, which, after passing through their proper 

 glands, enter the mesenteric glands ; and those of the descending colon, sigmoid 

 flexure, and rectum, which pass to the lumbar glands. 



THE LYMPHATICS OF THE THORAX. 



The Lymphatic Glands of the Thoracic Wall are the intercostal, internal mam- 

 mary, anterior mediastinal. and posterior mediastinal. 



The intercostal glands are small, irregular in number, and situated on each 

 side of the spine, near the costo-vertebral articulations, some being placed between 

 the two planes of intercostal muscles. 



The internal mammary glands are placed at the anterior extremity of each 

 intercostal space, by the side of the internal mammary vessels. 



The anterior mediastinal glands are placed in the loose areolar tissue of the 

 anterior mediastinum, some lying upon the Diaphragm in front of the pericardium, 

 and others round the great vessels at the base of the heart. 



The posterior mediastinal glands are situated in the areolar tissue in the poste- 

 rior mediastinum, forming a continuous chain by the side of the aorta and oesoph- 

 agus : they communicate on each side with the intercostal, below with the lumbar, 

 and above with the deep cervical glands. 



The Superficial Lymphatic Vessels of the Front of the Thorax run across the 

 great Pectoral muscle, and those on the back part of this cavity lie upon the 

 Trapezius and Latissimus dorsi ; they all converge to the axillary glands. The 

 lymphatics from the greater part of the mammary gland pass outward to the 

 lower border of the Pectoralis major muscle, where they enter a chain of small 

 glands situated in the axillary space along the lower border of its anterior 

 boundary. Some few lymphatics from the inner side of the mammary gland pass 

 through the intercostal spaces to reach the anterior mediastinal glands. 



The Deep Lymphatic Vessels of the Thoracic Wall are the intercostal, internal 

 mammary, and diaphragmatic. 



The intercostal lymphatic vessels follow the course of the intercostal vessels. 



