If a patient has a penetrating wound of his thigh, you may need to tie his femoral artery. If possible, tie it in his subsartorial canal, below its profunda branch, so that this can supply his leg via the anastomoses that its perforating branches make with the arterial plexus round his knee. If you tie it above its profunda branch, his circulation may be be maintained via the cruciate anastomosis with branches of his internal iliac artery, but this is less reliable.
The femoral artery starts at the mid inguinal point as a continuation of the external iliac artery. It runs down the thigh obliquely, first across the femoral triangle, and then underneath the sartorius muscle. It ends at the junction of the middle and lower thirds of the thigh, by going through a hole in the adductor magnus, and becoming the popliteal artery.
As the femoral artery crosses the femoral triangle, the femoral vein lies medial to it, becoming posterior distally; the femoral nerve lies about a centimetre laterally. Further on, when the femoral artery is in the canal underneath sartorius, the adductor longus and adductor magnus muscles lie behind it; vastus medialis lies anterolaterally. The femoral vein now lies posterolaterally, the nerve to vastus medialis laterally, and the saphenous nerve anteromedially.
The superficial epigastric artery, the superficial circumflex iliac artery, and the superficial and deep external pudendal arteries all arise from the femoral artery close to its origin. The profunda femoris artery arises about 3 cm below the inguinal ligament, runs medially behind the femoral artery, and finally breaks up into branches which run into the adductor muscles.
TYING THE FEMORAL ARTERY Flex the patient's thigh slightly, and rotate it laterally. If you plan to tie his femoral artery distal to his mid thigh, apply a tourniquet. Draw a line from his mid inguinal point to his adductor tubercle. His femoral artery lies under the upper two-thirds of this line[md]palpate it. Make an adequate incision at a suitable place along this line. His long saphenous vein lies in the superficial fascia. Try not to cut it. If by any chance you have to to tie his femoral vein, this will form the main venous collateral.
Incise his deep fascia, mobilize his sartorius muscle, and reflect this laterally to expose the upper part of his femoral and profunda arteries.
To expose the lower part of his femoral artery, reflect his sartorius medially, and divide the bridge of fibrous tissue which roofs his subsartorial canal. His femoral artery may be very difficult to find. If it is, release the proximal tourniquet (if you have applied one), and feel for pulsations.
Separate his femoral artery and vein carefully. Preserve the vein if you can. Proximally, they lie together within the femoral sheath, distally this becomes the femoral fascia. Pass an aneurysm needle round the artery, tie it with zero silk or linen, and don't divide it.
Fig. 3-10 EXPOSING THE POPLITEAL ARTERY is difficult, because, although the popliteal fossa looks easy in a diagram, in real life its contents are cramped together. A vertical incision is shown. A ''lazy S' incision is better. Adapted from ''Farquharson's Textbook of Operative Surgery', edited by RF Rintoul. Churchill Livingstone, with kind permission.