458 The Thigh 



and fascia lata. Then the crural sheath is sparingly opened and the 

 artery is seen, to the outside of the vein. The needle is passed from 

 the inner side. The anterior crural nerve is far out of sight (p. 358). 



Collateral circulation is established by the anastomosis of the 

 external circumflex with the gluteal, ilio-lumbar, and circumflexa ilii, 

 and with the sciatic branches in the cruciform anastomosis ; by the 

 anastomosis of the internal circumflex with the obturator, gluteal, and 

 sciatic ; of the superior perforating with the sciatic ; and of the per- 

 forating and superior muscular branches of the popliteal with the 

 comes nervi ischiatici. 



Xiigration of the superficial femoral in Scarpa's triangle is per- 

 formed at ' a hand's breath ' (four inches) below Poupart's ligament at 

 a spot in which the artery is comparatively near the surface, and distant 

 from the origin of any large branch. The line of the artery having 

 been taken (p. 447), or traced by the pulsations, as the limb lies 

 slightly flexed and everted upon a pillow, a three- or four-inch incision 

 is made with its mid-point over the chosen spot. In incising the 

 superficial fascia, the long saphenous vein, which is close on the inner 

 side, must be avoided ; the fascia lata is then divided on a director, 

 when the inner border of the sartorius is looked for, exposed, and 

 drawn outwards. The sheath of the vessels is thus brought into view 

 and is opened for ahput half an inch, along the aspect most distant 

 from the vein, which'is, of course, upon the side of the sartorius the 

 outer side. Unless this point be attended to the thin-walled vein is 

 in great danger of being wounded. The vein may not be seen, as it 

 is behind the artery, though slightly to the inner side ; the aneurysm- 

 needle is passed from the inner side, close around the artery, threaded, 

 and withdrawn. 



Migration in Hunter's canal is invariably performed in the case 

 of a punctured wound in that situation, and sometimes in the case of 

 aneurysm of the popliteal artery. A four-inch incision is made over 

 the line of the artery in the middle of the thigh, care being taken 

 to avoid the saphenous vein. The fascia lata having been divided, the 

 fibres of the sartorius are seen running evenly in the length of the 

 wound. Their direction distinguishes them from the oblique fibres of 

 the vastus internus and of the adductor longus. The muscle is then 

 drawn inwards, and the aponeurotic roof of the canal is exposed 

 perhaps with the saphenous nerve and the superficial part of the 

 anastomotica magna passing through it. The roof is then divided on 

 a director for an inch or so, when the saphenous nerve is found rest- 

 ing upon the sheath of the vessels. This sheath is cautiously opened 

 for about a quarter of an inch, the artery is isolated, and the needle is 

 passed from the outer side the side of the vein. 



In seeking the artery in Hunter's canal the fallacy is apt to be in 

 making the incision too low down, so that the operator finds his wound 

 deepening against the tendons of the gracilis and the adductor magnust 



