The external circumflex artery, [circumfiexa femoris interna s. posterior,] a branch of considerable size, arises from the outer side of the profunda, and, after passing outwards for a short distance beneath the sartorius and rectus muscles, and through the divisions of the anterior crural nerve, gives branches, which may be divided into three sets, according to the directions which they take.
The first incline transversely outwards, and after passing over the crureus, pierce the vastus externus, so as to get between it and the bone just below the great trochanter of the femur, and reach the back part of the thigh, where they anastomose with the internal circumflex and the perforating branches, also with the gluteal and sciatic branches. The second set, or ascending branches, are directed upwards beneath ihe sartorius and rectus, and afterwards under the tensor muscle of the fascia lata ; here they communicate with the terminal branches of the gluteal, and with some of the external descending branches of the circumflex iliac artery. The third, or descending set of branches, incline outwards and downwards upon the extensor muscles of the leg, covered by the rectus muscle. They are usually three or four in number, some being of a considerable size ; most of them are distributed to the muscles on the fore part of the thigh, but one or two can be traced as far as the knee, beneath the vastus externus muscle, where they anastomose with the superior articular branches (internal and external) of the popliteal artery, and with the anastomotic branch of the femoral artery.
Peculiarities. -The external circumflex branch sometimes arises (as a single trunk) from the femoral artery ; or it may be represented by two branches, of which, in most cases, one proceeds from the femoral, and one from the deep femoral ; both branches, however, have been seen to arise from the deep femoral, or, but much more rarely, both from the femoral artery.
The internal circumflex artery,s [circumfiexa fern, externa s. anterior,] smaller than the preceding branch, arises from the inner and back part of the deep femoral artery, and is directed backwards to the inner side of the femur, between the pectineus and the psoas muscles, so that only a small part of it can be seen without disturbing these muscles. On reaching the tendon of the external obturator, by which the vessel is guided to the back of the thigh, it divides into two principal branches. One, ascending, is distributed partly to the adductor brevis and gracilis, and partly to the external obturator muscle, near which it anastomoses with the obturator artery; the other, or transverse branch, passes backwards above the small trochanter, and appears on the back of the limb, between the quadratus femoris and great adductor muscle, where it anastomoses with the sciatic artery and with the superior perforating branches of the deep femoral artery. Opposite the hip-joint, this transverse branch gives off an articular vessel, which enters the hip-joint through the notch in the acetabulum, beneath the transverse ligament, and after supplying the adipose substance in that articulation, is guided to the head of the femur by the round ligament. In some instances the articular branch is derived from the obturator artery; sometimes the joint receives a branch from both sources.
Peculiarities. — With few exceptions, the peculiarities met with in the internal circumflex branch depend upon its transference to the femoral artery, and, in almost all cases, to a point above the origin of the profunda artery. Examples have also been met with in which the internal circumflex arose from the epigastric, or the circumflex iliac, or from the external iliac artery.
The perforating arteries (perforantes), so called because they reach the back of the thigh by perforating the adductor brevis and the adductor magnus muscles, are three or four in number. The first perforating artery passes backwards below the pectineus muscle, and through the fibres of the short and great adductor muscles ; after which it immediately divides into branches, which are distributed to both adductor muscles, to the biceps, and great gluteal muscles, and communicate with the sciatic and internal circumflex arteries. The second perforating artery, considerably larger than the first, passes through the adductor magnus ;
after which it divides into ascending and descending branches, which ramify in the hamstring muscles, and communicate with the other perforating branches. A branch, named the nutrient artery [nutriens] of the femur, enters the medullary foramen of that bone. The third perforating artery pierces the adductor magnus, and, like the others, is distributed to the long flexor muscles at the back of the thigh, anastomosing with the other perforating arteries above, and with the termination of the profunda artery itself below.
Termination of the deep femoral artery. — After having given off these different branches, the deep femoral artery becomes considerably diminished in size, and passing backwards close to the linea aspera, divides into smaller branches, some of which are distributed to the short head of the biceps, the rest to the other hamstring muscles.
These ultimate branches of the deep femoral artery communicate with those of the popliteal artery and with the lower perforating arteries already described.
The perforating arteries present no peculiarities of note. The terminal branch of the deep femoral, already described, is sometimes regarded as a fourth perforating artery.
Muscular branches of the femoral artery
In its course along the thigh the femoral artery gives off several branches [rami musculares] to the contiguous muscles. They vary in number from two to seven. They supply the sartorius and the vastus internus, with other muscles, which are close to the femoral artery. Their size appears to bear an inverse proportion to that of the descending branches of the external circumflex artery.
Close to its termination the femoral artery gives off a branch constant, but of small size, named the anastomotic artery (anastomotica magna), fig. 252,19 which descends in the same line as the femoral artery itself. Arising from that vessel, when about to enter the popliteal space, it descends upon the tendon of the adductor magnus, accompanied by the saphenous nerve. Having given off several branches, the anastomotic artery passes down to the inner condyle of the femur covered for a short distance by some of the fibres of the vastus internus muscle and, finally, anastomoses with the superior internal articular artery, and with the recurrent branch of the anterior tibial artery. Of its branches, one accompanies the saphenous nerve beneath the sartorius muscle; others pass obliquely outwards through the substance of the vastus internus, and communicate with the descending muscular branches in front of the thigh. From the lower part of the vessel, a branch crosses over the femur, a little above its articular surface, supplies branches to the knee-joint, and anastomoses with the superior external articular artery.— The anastomotic artery vanes not infrequently in size, and in the point at which it arises.
From Quain's anatomy.