The femoral artery is accessible to the surgeon for the application of a ligature without serious difficulty in its entire length ; but as the lower half is deeply placed, the difficulty of reaching this part is greatest, at the same time that the depth at which the vessel lies renders it necessary to divide and disturb the surrounding structures to a greater extent than where the vessel is nearer the surface. For these reasons the upper part of the artery is to be preferred for the performance of the operation adverted to, in all cases in which other circumstances do not control the choice of the surgeon. But the upper part of the femoral artery is not equally eligible for the application of a ligature at all points, in consequence of the position of the branches — an important consideration in the surgical anatomy of this vessel.
Close to the commencement of this artery are two considerable branches (epigastric and circumflex iliac) ; and between one and two inches lower down the deep femoral branch ordinarily takes its rise. A ligature placed on the arterial trunk in the interval between those branches, that is to say, on the common femoral artery, is in the near neighborhood of two disturbing causes, — two sources of danger, so near that the prospect of a favorable issue to the operation is under ordinary circumstances very small.
Moreover it has been shown amid the facts detailed above, that the origin of the deep femoral is often less than the average distance from Poupart's ligament; and that, not infrequently, a considerable branch (one of the circumflex arteries) takes its rise from the common femoral artery. When these circumstances are considered, the operation of tying the common femoral artery, or the femoral artery within two inches of its commencement, must be regarded as very unsafe. And it may be added, that the conclusion to which the anatomical facts would lead is fully confirmed by the results of cases in which the operation has been actually performed.
It remains to determine where a ligature applied to the main artery shall be sufficiently distant from the origin of the deep iemoral, below it, to be free from the disturbing influence of the circulation through that great branch. It has been shown that now and then a case occurs in which the profunda is given off at the distance of from two to three inches below Poupart's ligament — in only a single instance out of a large number of observations (431) did the space referred to amount to four inches.
From the foregoing remarks the inference to be deduced is, that the part of the femoral artery to be preferred for the operation supposed, is at the distance of between four and five inches below the lower margin of the abdominal muscles.
Remarks on the operation
The position of the artery being determined, and the integument and fat divided, a vein may be met with lying on the fascia, over the course of the artery. The saphenous vein being nearer to the inner side of the limb than the line of incision, is not seen in the operation. The fascia lata, which is now to be divided, has a more opaque appearance over the vessels than over the muscles, for the colour of the latter appears through the membrane.
After dividing the fascia, the edge of the sartorius muscle will, in many cases, require to be turned aside; and occasionally this muscle crosses the thigh so directly that it must be drawn considerably outwards in order to reach the artery. To the exact point at which the sheath of the vessels, and even the fascia, should be cut through, the pulsation of the artery will guide the operator. A small nerve may present itself in this part of the operation. The immediate investment of the artery should be opened to the smallest possible extent, and the knife or other instrument should be sparingly used at this stage of the operation ; the object being to disturb the artery from its connections, including its nutrient vessels (vasa vasorum) as little as possible, and likewise to avoid wounding any of the small muscular branches which spring from most arteries at irregular intervals. The division of an artery of the size of those last referred to at a distance from the source from which it springs is of little importance. It contracts, and soon ceases to bleed. But when it is divided close to the trunk, blood issues from it as it would if an opening equal in size to the calibre of the little branch were made in the trunk itself.
In order to avoid injuring the vein, which is separated from the artery only by a thin cellular partition, the point of the aneurism needle, which conveys the ligature, is to be kept close to the artery.
Other veins of occasional occurrence may render increased care necessary, for example, those small branches which cross the artery or course along its surface; or it may be a larger vein — a division of the femoral vein when it is double, or the deep femoral vein when the ligature is applied a little higher than usual.
To reach the femoral artery in the middle of the thigh, the depth of the vessel being considerable, the incisions through the integuments must be proportionably long. As the sartorius is directly over the vessel, the operation may be performed by turning the muscle either towards the outer or the inner side of the limb; and the incision would be made, according to the plan adopted, at the inner or the outer margin of the muscle. The preferable mode appears to be, to divide the integument on or over the muscle, near its inner margin, so as to arrive directly upon the muscle and draw it outwards, after cutting freely through the investing fascia. The fibrous structure stretched over the vessels from the adductors to the vastus internus muscle being divided, the positions of the femoral vein and saphenous nerve are to be kept in view in completing the operation. In the first steps of the operation in this part of the thigh, injury to the long saphenous vein is to be guarded against.
Before concluding the observations on the femoral artery, a very small class of cases claims a word of notice. It has happened* that the application of a ligature to a femoral artery has not been followed by the usual consequence of cessation of the pulsation in the aneurism ; and the uninterrupted continuance of the circulation was found, on examination after death, to be attributable to the circumstance of the artery being double where the ligature was applied, while the two parts became reunited above the tumor. If such a case should be again met with in an operation, the surgeon, instructed by the case alluded to, and by other examples of the same arrangement of the arteries which have since been observed, might at once, under the guidance of the pulsation, or of the effect of pressure in controlling the circulation through the .aneurism, divide the cellular covering of the second part of the artery, and tie it likewise.
From Quain's anatomy.