When the profunda artery arises very near to or above Poupart's ligament, and from the outer side of the femoral, is large and pursues its ordinary course, two arteries of equal or nearly equal size may he found, at the upper part of the inguinal region, side by side, and upon the same level, and thence liable to be taken, either of them, for the femoral artery. When such an arrangement occurs, the ex ternallj of the two vessels will almost certainly be found to be the profunda, for if that artery have once passed inward behind the femoral, it cannot afterward gain the same level with it, so as to be situate at the same time internal to and on the same plane with it : further, as the profunda descends, it recedes from the an terior surface more than the femoral, in order to pass behind the adductor longus, and thus it gains at the lower part of the region a deeper situation than the other. But inasmuch as the profunda occasionally arises from the inside of the femoral artery, it may be possible for it, in case of high origin, to be the inner of the two vessels adverted to. Such a circumstance, however, if it ever occur, must be extremely rare, but in order to guard against it, the pre caution recommended of alternately compres sing the vessels and ascertaining the effect previous to the application of a ligature, should never be neglected.
Branches of the profunda artery.--The pro-. funds gives off a considerable number of branches, some of which being distributed to the muscles, by which the artery passes, and not being remarkable either for their size or their communications, have not received par ticular names. Those which are most de serving of attention, whether for their size, the extent and peculiarity of their course, or the anastomoses which they form with other arteries, are five or six in number, viz. two circumflex arteries, and three or at times four perforating arteries. The circumflex arteries are so named because they wind round the upper extremity of the femur, and form an arterial circle around it : they are distinguished by the epithets external and internal, being destined, one to the outer, the other to the inner side of the limb : they are vessels of considerable size and importance because both of the extent of parts which they supply, and of the communications which are established through them between the femoral, the arteries of the pelvis, and those of the lower parts of the limb.
1. The external circumflex artery at times is the first branch of the profunda; at others it is preceded by the internal circumflex : it is given off from the profunda while it lies on the outside of the femoral at a variable dis tance from Poupart's ligament, and arises from the outer side of the artery : occasionally it is given off by the femoral itself; it runs directly outward, or outward and downward, in front of the psoas and ilium muscles; beneath the sartorius and rectus, and either between or behind the divisions of the crural nerve; and divides after a short course into three branches, viz. an ascending, a descending, and a circum
flex.
a. The first, the ascending branch, runs up.. ward and outward toward the superior anterior spinous process of the ilium, between the iliacus internus and the glutceus medius mus cles, and concealed by the tensor vagina femoris : as it proceeds, it gives branches to those muscles; and having reached the outer and hack part of the spinous process, it ter minates in an anastomosis with a branch of the glutceal, and also with the deep cir cumflex ilii arteries. The anastomosis with the glutceal artery becomes remarkably en larged when the main vessel is interrupted above the origin of the profunda, as may be seen from Sir A. Cooper's case of femoral aneurism.* b. The second, the descending branch, runs downward and outward beneath the rectus muscle, between it and the triceps crural, and divides after a short course for the most part into several branches of considerable size and great length for the supply of those muscles and for establishing communications: the branches are at times so many as five or six, and are dis tributed one or more to the rectus, entering the muscle upon its deep surface, and pro longed to a great length within its substance; one to the vastus internus, one to the crurwus, and one or two to the vastus externus : they are accompanied, several of them, by branches of the crural nerve, and they run for a con siderable distance, particularly the infe rior branch to the vastus externus, between the divisions of the triceps crural muscle, before entering their substance: they are pro longed very low down, and may be followed some of them to near the knee, where they anastomose with branches of the femoral in the vastus internus, and with the superior articular arteries. But the branches of the descending division of the external circum flex artery are by no means uniform in number or destination, more or fewer of the arteries just described being at times branches of the profunda itself; thus, at times that to the vastus internus, that to the crurmus, and that to the reetus, arise from the profunda below the circumflex, and in such case the descend ing branch of the latter consists solely of the branch or branches destined to the vastus ex temus muscle.