The Popliteal Space. 349 



late an aneurism. To assist in differentiating a bursitis 

 in this situation from an aneurism, it is worthy of note, 

 that the pulsations conveyed to the finger are more evident, 

 in bursitis, when the limb is extended, whereas, they are 

 better appreciated, in aneurism, when the limb is flexed. 

 The reason being that, when the limb is extended in bur- 

 sitis, the popliteal fascia is rendered more tense and, 

 therefore, presses the bursa more firmly upon the artery 

 with the result that the force of the pulsations is in- 

 creased ; whereas, when the limb is flexed, the pressure on 

 the bursa being relieved, the pulsations are less evident. 

 The pulsations of an aneurism, however, are more pro- 

 nounced, when the limb is flexed, since, the flexion relaxes 

 the popliteal fascia and the finger can, therefore, better 

 appreciate the aneurismal sac and its pulsation. Again, 

 compression of the femoral artery lessens, to a very slight 

 degree, the size of a bursa ; whereas, it lessens, to a 

 marked degree, the size of an aneurism. In many cases, 

 this bursa is connected with the joint, and hence, the 

 contents may be gently pressed into the cavity of the joint, 

 when the limb is slightly flexed, since this position en- 

 larges a slit-like opening which communicates with the 

 joint and which is probably closed when the limb is ex- 

 tended. The possibility of many of these bursae communi- 

 cating with the joint should always be kept in mind, in 

 operating them, because of the danger of subsequent in- 

 fection of the articulation. 



Aneurism. There are a number of reasons that 

 influence the production of an aneurism of the popliteal 

 artery : ( 1 ) The effects of extension or flexion of the leg 

 on the calibre of the vessel. That the position of the limb 

 has an influence on the size of the vessel is evident from 

 the fact, that extreme flexion may entirely occlude the 

 artery, as shown by Maunoir this is taken advantage of 



