536 OPEEATIONS ON THE CIBCULATORY SYSTEM. 



Fia. 460.— Improperly-made Knot. 



a second straight knot is made (Fig. 459). The knot represented 

 in Fig. 460 is improperly made and liable to become loosened. 

 The extremities of the thread are left of a suificient length to 

 allow their being turned toward the most dependent part of the 

 wound. If they are cut too short they are Uable to become loose 

 in the tissues, and be covered or concealed by the granulations and 

 become the center of a suppurative gathering. Ligatures intended 

 to remain in the tissues, must be made of animal material. 



The wound of an artery always involves the application of a 

 ligature on both extremities of the course, the central and the 

 peripheric. 



Where the artery cannot easily be raised or dissected from the 

 tissues into which it is retracted, the pointed tenaculum can be 

 used to draw it out of its position ; this instrument is more suita- 

 ble for small than large vessels, the coat of which it is Liable to tear. 



In the immediate ligating of an intact artery, and without a 

 solution of continuity, the vessel is exposed by means of an in- 

 cision, either parallel or sometimes obUque, and at others perpen- 

 dicular to the artery, according to its situation and the nature of 

 the subjacent tissues, carefully noting any projections of the 

 bones, muscles, or tendons which can be made available as points 

 de repire; observing, indeed, all the anatomical connections exist- 

 ing between the different structures. When the artery has been 

 nearly reached, in order to avoid injuring it, it shoidd be separated 

 by dissection with the forceps and the bistoury from the tissues 

 covering it, or by introducing a blunt, grooved director under 

 them, as a guide, and dividing them with the knife. The sheath 

 of the vessel is also carefully divided and separated from the ves- 

 sel itself, which is then carefully isolated from its vein or surround- 

 ing adhesion, and the blunt-eyed tenaculum, or the aneurism 



