OF THE VESSELS IN GENERAL. 243 



fiexa ilii communicate at the same time above with the vessels 

 of the trunk, and below with the vessels of the knee, and these 

 vessels at the same time communicate also with the branches 

 proceeding from the vessels of the leg. 



Generally the vessel or vessels which result from an anasto- 

 mosis, are more voluminous than either of the anastomosing 

 vessels and less than both united. 



Anastomoses are so much the more frequent as they o.ccur be- 

 tween smaller vessels and in parts the more distant from the 

 centre; they occur also between larger branches in the extre- 

 mities; for instance, in the cavity of the cranium, in the hand 

 and in the foot. In most cases they establish a communication 

 between vessels, whose origin is very near; in some cases 

 they cause vessels, the origin of which is pretty distant, or 

 even very distant, as for instance, from the subclavicular to 

 the inguinal regions. The anastomoses of the sanguineous 

 vessels are more numerous and larger around the articulation, 

 than in the parts between them; those of the veins and of the 

 lymphatic vessels are very frequent between the principal 

 trunks; those of the veins particularly, are much multiplied 

 under the skin. 



We may form an idea of the number and importance of ana- 

 stomoses since the aorta* may be narrowed, obliterated, even 

 tied without preventing the circulation or the injection to 

 reach every part of the body; that the largest veins,t even the 

 venae cavse being obliterated, nevertheless the blood circulates; 

 and that the thoracic ductj has been obliterated or tied with 

 impunity. 



Anastomoses facilitate and render more uniform the circu- 

 lation of the fluids of the body. 



357. The larger vessels follow a pretty straight course, 

 generally parallel to the axis of the body; this is the reason 



* Scarpa on Aneurism. A. Cooper and B: Travers' Surgical Essays, 

 part i. Lond. 1818. 



} J. Hodgson, Affections of the Arteries and Veins. 



t Flandrin, Journal de Medicine, torn. Ixxxvii. Paris, 1791. A. Cooper, 

 in Medical Records and Researches, &?c. Loud. 1813. 



