<)96 THE VASCULAR SYSTEMS 



The popliteal artery is more frequently the seat of aneurism than is any other artery in the 

 body, with the exception of the thoracic aorta. This is due, no doubt, in a great measure, to 

 the amount of movement to which it is subjected, and to the fact that it is supported by loo.se and 

 lax tissue only, and not by muscles, as is the case with most arteries. 



Ligation of the popliteal artery is required in cases of wound of that vessel, but for aneurism 

 of the posterior tibial it is preferable to tie the superficial femoral. The popliteal may be tied 

 in the upper or lower part of its course; but in the middle of its course the operation is attended 

 with considerable difficulty, from the great depth of the artery and from the extreme degree of 

 tension of the lateral boundaries of the space. 



In order to expose the vessel in the upper part of its course, the patient should be placed in 

 the supine position, with the knee flexed and the thigh rotated outward, so that it rests on its 

 outer surface; an incision three inches in length, beginning at the junction of the middle and 

 lower third of the thigh, is to be made parallel to and immediately behind the tendon of the 

 Adductor magnus, and the skin, superficial and deep fascia divided. The tendon of the muscle 

 is thus exposed, and is to be drawn forward and the Hamstring tendons backward. A quantity 

 of fatty tissue will now be exposed, in which the artery will be felt pulsating. This is to be 

 separated with the point of a director until the artery is exposed. The vein and nerve will not 

 be seen, as they lie to the outer side of the artery. The sheath is to be opened and the aneurism 

 needle passed from before backward, keeping its point close to the artery for fear of injuring the 

 vein. The only structure to avoid is the long saphenous vein in the superficial incision. The 

 upper part of the popliteal artery may also be tied by an incision on the back of the limb, along 

 the outer margin of the Semimembranosus, but the operation is a more difficult one, as the 

 internal popliteal nerve and the popliteal vein are first exposed, and great care has to be exercised 

 in separating them from the artery. 



To expose the vessel in the lower part of its course, where the artery lies between the two 

 heads of the Gastrocnemius, the patient should be placed in the prone position with the limb 

 extended. An incision should then be made through the integument in the middle line, com- 

 mencing opposite the bend of the knee-joint, care being taken to avoid the external saphenous 

 vein and nerve. After dividing the deep fascia and separating some dense cellular membrane, 

 the artery, vein, and nerve will be exposed, descending between the two heads of the Gastroc- 

 nemius. Some muscular branches of the popliteal should be avoided if possible, or, if divided, 

 tied immediately. The leg being now flexed, in order the more effectually to separate the two 

 heads of the Gastrocnemius, the nerve should be drawn inward and the vein outward, and the 

 aneurism needle passed between the artery and vein from without inward. 



Branches. The branches of the popliteal artery are: 



,.. . ( Superior. Superior external articular. 



\ Inferior or sural. Azygos articular. 



Cutaneous. Inferior internal articular. 



Superior internal articular. Inferior external articular. 



The superior muscular branches, two or three in number, arise from the 

 upper part of the popliteal artery, and are distributed to the lower part of the 

 Adductor magnus and Flexor muscles of the thigh, anastomosing with the fourth 

 perforating branch of the profunda. 



The inferior muscular or sural (aa. surales) are two large branches which are 

 distributed to the two heads of the Gastrocnemius and to the Plantaris muscle 

 They arise from the popliteal artery opposite the knee-joint. 



The cutaneous branches arise separately from the popliteal artery or from 

 some of its branches; they descend between the two heads of the Gastrocnemius 

 muscle, and, piercing the deep fascia, are distributed to the integument of the 

 calf. One branch usually accompanies the short, or external, saphenous vein, 

 the superficial sural artery. 



The superior articular arteries, two in number, arise one on each side of the 

 popliteal, and wind around the femur immediately above its condyles to the front 

 of the knee-joint. The internal branch (a. genu superior medialis) winds inward 

 beneath the Hamstring muscles, to which it supplies branches, above the inner 

 head of the Gastrocnemius, and, passing beneath the tendon of the Adductor 

 magnus, divides into two branches, one of which supplies the Vastus interims, 



