The adequacy of the collateral circulation in the thigh to the maintenance and nutrition of the limb after the interruption of the femoral artery, has been so long established that it is at present unnecessary to insist upon it. But the channels through which the circulation of the blood becomes in such cases restored, as well as the relations of the new circulation, are deserving of attention.
The collateral connections of the femoral artery are distinguishable into those between it and the arteries of the trunk, those between it and the popliteal and arteries of the leg, and those between different parts of its own course. The communication of the femoral artery with the arteries of the trunk are established between it and both the internal and the external iliacs.
Those with the internal iliac are formed, 1. by mean's of the inosculations of the branches of the profunda, the circumflex and perforating arteries with the obturator, glutceal, and sciatic arteries, all branches of the latter; 2. by those between the internal and external pudics; and, 3. by the communications of the ilio-lumbar artery with the deep anterior iliac, by which the blood may be transferred to the superficial an terior iliac or the external circumflex.
From the obturator artery the blood is transmit ted through theascending branches of the internal circumflex : this channel of communication be comes, in cases of interruption of the external iliac artery, remarkably free, the branches esta blishing it being much enlarged and tortuous : instances and representations of it may be found in the Medico-Chirurgical Transactions, vol. iv. and in Guy's Hospital Reports, No. 1, Jan. 1836, from the experience of Sir Astley Cooper.
Through the glutceal artery the femoral com municates with the internal iliac by the inoscu lations between that vessel, the posterior tro chanteric and the ascending terminal branches of the internal circumflex, and by those between it and the ascending and circumflex branches of the external circumflex artery : those connec tions are displayed also in the works just referred to.
The communication of the femoral with the internal iliac through the sciatic artery is esta blished by the anastomosis of that vessel with the internal circumflex and the perforating arte ries, for which also see the same works.
The alteration in the condition of the sciatic artery or its branches caused by ligature of the femoral or of the external iliac artery presents one of the most remarkable results of that cir cumstance : its branch to the sciatic nerve be comes greatly enlarged, very tortuous, and so much elongated as to form at times a commu nication between the sciatic artery and the posterior tibial. The connections established through the pudic and ilio-lumbar arteries are set forth, in the event of a case of ligature of the external iliac artery published in the Medico Chirurgical Transactions, vol. xx. by Mr. Norman.
The femoral artery communicates with the external iliac through means of the anastomoses between the anterior iliac arteries, internal and external, between the internal anterior iliac and the external circumflex ; and also by those be tween the superficial and internal epigastrics.
By the communications, which have been mentioned, the transmission of blood through the femoral artery may be restored, after the interruption of the external iliac artery, or of the femoral above the origin of the profunda, with sufficient freedom for the perfect nutrition of the limb ; of which numerous instances have been observed by different writers.
The upper and lower parts of the femoral artery are also connected by collateral channels. Those are established by the communications which exist between the branches of the pro funda artery arising from the upper extremity of the femoral, and branches of the latter given off during its course or from its lower extre mity; thus the blood may pass from the femo ral artery above into the middle part of the vessel through the anastomosis existing between the descending branches of the external circum flex artery, and the branches given by the femo ral to the vastus internus muscle about the middle of the thigh.
A similar communication exists upon the internal side of the femoral by means of the anastomoses by which descending branches of the internal circumflex are connected with those given by the femoral itself to the adductors.