THE LYMPH VASCULAR SYSTEM. 



993 



to the aperture of the pelvis minor, where it passes in front of the left common iliac artery 

 and becomes the inferior mesenteric vein. 



The inferior mesenteric vein runs upwards, on the left of the aorta, behind the peritoneum 

 and in front of the left psoas major muscle and the left internal spermatic artery. Near its 

 termination it crosses in front of the left renal vein, and, passing behind the body of the pancreas, 

 ends in the splenic vein. Occasionally it terminates in the angle of union of the superior 

 mesenteric and splenic veins. 



Tributaries. In addition to the superior haemorrhoidal vein, of which it is the direct con- 

 tinuation, the inferior mesenteric vein receives sigmoid tributaries from the iliac and pelvic 

 colon, and the left colic vein from the descending colon and left colic flexure. 



THE LYMPH VASCULAR SYSTEM. 



Right internal jugular vein 

 Right jugular trunk / Broncho-mediastinal duct 



Left internal jugular vein 



Right subclavian 

 trunk 



Left subclavian 



vein 



Left innominate 

 vein 



"^ Thoracic duct 



"* Superior vena cava 



Thoracic duct 



The vessels of the lymph vascular system, vasa lymphatica, contain a colourless 

 fluid, rich in white corpuscles, which is called lymph. 



In many respects the lymph vessels resemble blood-vessels, especially veins, 

 and, like the veins, many of the 

 lymph vessels, but not all, contain 

 numerous valves, which control the 

 direction of the circulation. Un- Right subcla ;' e tn 



like the veins, however, the lymph 

 vessels communicate directly or 

 indirectly with the great serous cavities of 

 the body ; and also unlike the veins, the 

 continuity of the lymph vessels is inter- 

 rupted by interposed nodular aggregations 

 of lymphoid tissue which are known as 

 lymph glands. 



The corpusculated fluid called lymph, which 

 fills the interiors of the lymph vessels, is partly 

 collected from the serous cavities, and, in part, it 

 passes into the lymph vessels from the surround- 

 ing tissues. It is carried by the lymph vessels to 

 the veins*; for the smaller lymph vessels gradually 

 unite together to form larger and larger channels 

 until, ultimately, all the lymph passes into two 

 main trunks the thoracic duct, which terminates 

 in the commencement of the left innominate 

 vein, and the right lymph duct, which ends in the 

 beginning of the right innominate vein. 



Obviously, therefore, all the lymph vessels 

 are afferent inasmuch as they carry the lymph 

 towards the great central vessels, but it is 

 customary to speak of some of the lymph vessels 

 as vasa afferentia and others as vasa efferentia, 

 the former being vessels which carry lymph to 

 lymph glands, and the latter, those which convey 

 the lymph from more peripheral towards more 

 central glands. 



The lymph vessels merely collect and convey 

 lymph ; the lymph glands probably serve in part 

 as filters and in part as the sources of origin of 

 some of the lymph corpuscles, which are called 

 lymphocytes and which become white blood cor- 

 puscles when they enter the blood stream. 



In its course from the tissues to the blood- 

 vessels the greater part, if not the whole, of the 

 lymph passes through one and generally through more than one lymph gland. 



All parts of the body which possess blood-vessels, except the central nervous 



64 



Cisterna chyli 



__._ .Left lumbar trunk 

 -- Right lumbar trunk 



Intestinal lymph 

 vessels 



Testicular lymphatics 



Lymph vessels from 

 "pelvis 



Lymph vessels from 

 lower extremity 



FIG. 797. DIAGEAM OF MAIN 

 LYMPH VESSELS. 



