This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
Hunter's canal occupies approximately the middle third of the thigh. It has an outer wall formed by the vastus internus muscle; a floor formed above by the adductor longus, and below by the adductor magnus; and a roof formed by a layer of fascia running from the adductor longus and magnus below to the vastus internus on the outer side. The canal runs from the apex of Scarpa's triangle to the opening in the adductor magnus muscle. The sartorius muscle lies on the roof of the canal (Fig. 533).
The femoral artery in Hunter's canal has the vein, to which it is closely bound by fibrous tissue, first posterior and then slightly to its outer side. The internal or long saphenous nerve crosses the artery in front from its outer to its inner side. At the beginning of the canal the nerve to the vastus internus runs alongside of the long saphenous nerve, but it soon leaves it to enter the muscle. The long saphenous nerve leaves the artery as the latter perforates the adductor magnus and passes downward under the sartorius muscle to be distributed to the leg lower down, and to the inner side of the ankle.
In ligating the artery the incision is made over the sartorius muscle, which is to be pulled to the outer side; this exposes the roof of the canal, which is then opened. There is no need of including the long saphenous nerve in the ligature. Just before the femoral artery pierces the adductor magnus it gives off the anastomotica magna, whose superficial branch follows the long saphenous nerve, while its deep branch supplies the vastus internus muscle. This latter branch may be the source of troublesome hemorrhage in supracondylar osteotomy.
Fig. 534. - Ligation of the femoral artery at the apex of Scarpa's triangle.
After ligation of the femoral artery below its profunda branch the external circumflex artery anastomoses with the muscular branches of the femoral, anastomotica magna, and superior articular arteries. The perforating arteries anastomose with the muscular branches below the ligature and with the superior articular arteries (Fig. 535).
The long saphenous vein begins in the venous arch on the dorsum of the foot and passes upward just in front of the internal malleolus, then along the inner posterior edge of the tibia, accompanied by the long saphenous nerve, then along the posterior border of the internal condyle and up in almost a straight line to the saphenous opening, 4 cm. (11/2 in.) below and to the outer side of the spine of the pubis, where it empties into the femoral vein. It is this vein which is involved in varicose veins of the leg, and is frequently operated on. The blood from the inner and outer portions of the thigh collects into two veins which empty into the long saphenous before the saphenous opening is reached, or else join the vein at the saphenous opening, or else open separately into the femoral vein. There are then sometimes two or three veins at the saphenous opening coming from below, instead of one. This is important to bear in mind when operating here, otherwise one of the side veins may be ligated or excised under the impression that it is the main trunk. Every opportunity should be utilized to impress on one's mind the exact course pursued by the vein, as otherwise it may not be readily found if not rendered conspicuous by distention or disease.
Fig. 535. - Collateral circulation after ligation of femoral artery.