278 CLINICAL APPLIED ANATOMY. 



be a matter of considerable difficulty, seeing that the dilatation 

 upon the vessel so markedly alters the normal anatomical 

 relations. It may be under these circumstances by no means 

 easy to find the main vessel on the proximal or distal side of 

 the sac, and to apply the two needful ligatures to it. Again, the 

 accompanying vein (or veins) may be so closely applied to or 

 stretched out upon the aneurysmal sac that it is well-nigh 

 impossible to prevent injury to or even removal of the venous 

 channel. Hence it follows that gangrene may be almost invited 

 by the procedure required for the removal of the sac. The 

 remarks here given apply in a peculiar sense to a popliteal 

 aneurysm. 



A very much more simple, and at the same time not infre- 

 quently efficacious, operation is to ligature the main artery 

 leading to the sac on the proximal side of the aneurysm. The 

 vessel may be ligated fairly close to the sac or at some distance 

 on the proximal side, the point chosen depending to a very great 

 extent upon the length of proximal artery available. The 

 operation of ligature of the artery on the proximal side at some 

 considerable distance from the sac is probably the better of the 

 two operations, and that for certain anatomical reasons. The 

 artery will here be in its normal anatomical relations, will be 

 less likely to be unsound, particularly in the matter of dilatation 

 of its coats, and will be readily separated from the veins in its 

 proximity. Further, ligature at this point will secure a freer 

 collateral circulation. Since the artery remains pervious from a 

 short distance below the ligature to the aneurysm, blood can 

 enter it by collateral anastomosis, and so eventually reach the 

 aneurysmal sac, but in a small stream and under diminished 

 pressure. Hence it follows that there will be a greater likelihood 

 of the clotting of the blood thus introduced into the sac, and so 

 a greater probability of cure. It will also follow that the opening 

 up of this collateral circulation will tend to diminish the 

 possibility of subsequent gangrene. 



Where there is not room for a proximal ligature to be applied 

 to the artery feeding the sac, it may be advantageous to ligate 



