This section is from the book "Anatomy Of The Arteries Of The Human Body", by John Hatch Power. Also available from Amazon: Anatomy of the Arteries of the Human Body, with the Descriptive Anatomy of the Heart.
The Perforating Arteries are three in number; the termination of the profunda is often described as a fourth. The first arises a little below the lesser trochanter ; it passes backwards beneath the lower edge of the pectineus muscle, and above the adductor brevis, and pierces the aponeurosis of the adductor magnus: sometimes it passes through the adductor brevis muscle. It then divides into two principal branches, one of which ascends in the substance of the glutaeus maximus, while the other descends in the long head of the biceps, and also supplies the vastus externus, semi-membranosus, and semi-tendinosus muscles. This artery anastomoses with the glutaeal, sciatic, circumflex, and inferior perforating arteries. The second is the largest of the perforating arteries: it arises a little below the preceding, and pierces the tendons of the adductor brevis and magnus, sometimes of the great adductor only; it then divides into several branches which supply the glutaeal and hamstring muscles, and communicate with the other perforating arteries. It also gives off the nutritious artery of the femur, or artery of the medullary membrane: this small vessel enters a foramen in the linea aspera usually near the centre of the bone; from this it runs along a canal which passes obliquely through the compact tissue of the bone towards its upper extremity, and ramifies on the medullary membrane. The third is the smallest of the three; it passes backward below the adductor brevis, then pierces the aponeurosis of the adductor magnus, and its branches are distributed in the same manner as the two other perforating arteries.
The Terminating Branch appears as the continuation of the profunda itself, though greatly diminished in size: it lies upon a plane posterior to the adductor longus muscle, perforates the adductor magnus, supplies the hamstring muscles and inosculates with the perforating arteries, and the articular arteries about the knee. This vessel is sometimes called the fourth perforating artery.
After the femoral artery has given off its anastomotic branch, it descends obliquely backwards through an oblique slit or opening between the adductor magnus muscle and the vastus internus, and, having arrived in the popliteal space, becomes the popliteal artery. The opening is bounded on the outside by the vastus internus; on the inside by the adductor magnus; inferiorly by the union of the tendon of this last muscle with the tendon of the vastus internus, and superiorly by the union of the tendons of the adductors longus and magnus. Its circumference is entirely tendinous, in order to provide against any obstruction to the circulation which would arise from the pressure of the muscular fibres upon the artery and vein in their passage through the opening.