Scarpa's triangle is a triangular space, the apex of which is directed downward, and the sides formed externally by the sartorius muscle, internally by the inner border of the adductor longus muscle, and above by Poupart's ligament. The floor of the space is formed from without inward by the ilio-psoas pectineus and the adductor longus muscles. The space is divided into two nearly equal divisions by the femoral vessels, which extend from the middle of its base to its apex, the artery giving off in this situation the superficial and profunda branches, and the vein receiving the deep femoral and the internal saphenous veins. Besides the vessels and nerves this space contains some fat and lymphatics.
Hunter's canal is the aponeurotic space in the middle third of the thigh, extending from the apex of Scarpa's triangle to the femoral opening in the adductor magnus muscle. Hunter's canal contains the femoral artery and vein inclosed in their own sheath of areolar tissue, the vein being behind and on the outer side of the artery, and the long saphenous nerve lying at first on the outer side and then in front of the vessels.
Linear Guide.—The guide for the femoral artery is represented by a line drawn from the center of Poupart's ligament to the inner side of the knee joint.
Poupart's ligament extends from the crest of the ileum bone to the top of the pubic bone. To determine the center of Poupart's ligament for the right leg, get on the right side of the body and with the left hand, place the second finger on the top of the pubic bone and the thumb on the crest of the ileum bone, then let the index finger drop down between the two which will represent the commencement of the femoral artery.
Anatomical Guide.—The artery runs through the center of Scarpa's triangle from the center of its base to its apex. In the middle third of the thigh the artery passes beneath the vastus medialis muscle and enters Hunter's canal.
Relation of the Artery, Vein and Nerve.—The femoral vein at Poupart's ligament lies close to the inner side of the artery, separated from it by a thin fibrous partition; but two inches down the vein runs behind the artery and then to its outer side.
There is no nerve in relation to the artery in the upper third, the anterior crural nerve lies about half an inch to the outer side of the femoral artery, being separated from the artery by the ilio-psoas muscle. In the middle third of the thigh the internal saphenous nerve is situated on the outer side of the artery, but not usually in the same sheath with the artery.
To raise the femoral artery in its proper place, is to measure down from Poupart's ligament from one and one-half to two inches in the linear guide, and there begin the incision, making it two inches or less in length. This will bring the incision below the point where the collateral branches are given off. Cut through the skin, then the fat, which will vary in thickness with the subject. Underneath the fat are several layers of deep fascia, which must be split the length of the incision.
The femoral artery will then be seen, and underneath it will be the femoral vein. Both will be in the same common sheath of fascia, which may be removed with a hook by gently tearing the sheath loose over the artery. When the artery has been loosened the length of the incision, raise it to the surface, placing a bone separator underneath for a bridge.
If it is desired to remove the blood, the femoral vein should then be raised.