When the interruption of the femoral occurs below the origin of the profunda, the oblitera tion of the trunk is no farther necessary than between the interruption and the origin of the profunda on the one hand, if no other branch intervene, and that of the next considerable branch upon the other. In such case the pro funda artery becomes the main channel of the circulation through the lower extremity from its origin downward, and the femoral with its branches thenceforth are to be regarded as branches of it.
But when the interruption arises from aneu rism and the operation necessary for its cure, obliteration of the femoral, to a greater or less extent according to the case, for the most part ensues: this appears to depend upon the in fluence, which the mode of cure of the disease exerts upon the circulation through the vessel, for the coagulation of the contents of the sac being generally produced by the interruption of the current of blood, the passage through the sac becomes obstructed, and along with it an extent of the artery upon both sides of the seat of the aneurism greater or less according to the disposition of the adjoining branches. The extent to which the obliteration of the artery has been found to proceed, has been different in different cases, but the varieties observed have been the following: 1. As re gards that part of the vessel which is above the ligature, when the femoral artery has been tied below the origin of the profunda for po pliteal aneurism, the vessel has been found, when the ligature has been applied to the lower part of the artery, either obliterated from the ligature to the origin of the pro.. funda, as occurred in the first subject upon whom M r. unter. operated for popliteal aneu rism according to his method, or obliterated upward only as far as the origin of those mus cular branches of the artery, which arise below the profunda and anastomose with the articular arteries. 2. W'heit the ligature has been ap plied near to the origin of the profunda, as in the operation of Scarpa, between it and the origin of the branches alluded to, the artery has been found obliterated from the point of interruption to the origin of the profunda.
The condition of the artery below the seat of the ligature is equally subject to variety Recording to circumstances, and is still more deserving of attention than the former : it has been found in one of three states, either ob literated throughout from the origin of the profunda down to the extremity of the popli teal artery, as occurred in the case reported by Sir A. Cooper in the Medico-Chirurgical
Transactions, vol. ii., or pervious throughout from the point of application of the ligature to the scat of the aneurism, where it was obliterated. Of this condition several in stances are cited by Hodgson,* and a most remarkable one is in the possession of Mr. Adams of this city, through whose liberality the author is permitted to introduce a notice of it. It was obtained from a patient who had been operated on by the late Professor Todd, and is remarkable, t. because the operation had been performed upon both limbs, and the condition of both is, as nearly as may be, the same; 2. because the obliteration at the seat of the ligature does not on either side exceed an inch, on one not being more than half that length ; and, 3. because the artery is pervious on both sides from the obliteration of the ligature to the lower part of the popliteal artery, the obliteration at the seat of the dis ease appearing not to have extended beyond it; and being, on both sides, about two inches long. Thirdly, the artery has been found par tially and irregularly obliterated, the vessel being closed at and for some distance below the seat of the ligature; being then pervious, the blood being conveyed into it by the in osculations between the minor branches of the artery arising below the interruption and those of the profunda from above; and again im pervious below, the blood being conveyed from it by similar branches anastomosing with the articular arteries.
The effect of ligature of the external iliac upon the femoral artery, independent of the influence of aneurism, has been already ad verted to. That effect is liable to be modified by the presence of the disease; thus in a case related by Sir A. Cooper in the fourth volume of the Medico-Cliirurgical Transactions, in which the iliac was tied for aneurism of the femoral artery at the middle of the thigh, the latter vessel was obliterated from the origin of the profunda downward. The case, re corded by Mr. Norman, already referred to, in which the external iliac was also tied, presents another remarkable modification: in at the femoral remained pervious, but the root of the profunda was obliterated, while its branches were open.