BRANCHES OF THE POPLITEAL ARTERY. 



443 



The other branch runs close to the femur, ramifies upon it, and also on 

 the knee-joint, and communicates with the upper external articular artery. 



(6) The upper external articular artery passes outwards a little above 

 the outer condyle of the femur, under cover of the biceps muscle, and, 

 after perforating the intermuscular septum, divides into a superficial and a 

 deep branch. The latter, lying close upon the femur, spreads branches 

 upon it and the articulation, and communicates with the preceding vessel, 

 with the anastomotic of the femoral, and with the lower external articular 

 artery ; the superficial branch descends through the vastus to the patella, 

 anastomosing with other branches and assisting in the supply of the joint. 



(c) The lower internal articular artery passes downwards below the 

 internal tuberosity of the tibia, lying between the bone and the internal 

 lateral ligament ; its branches ramify on the front and inner part of the 

 joint, as far as the patella and its ligament. 



(d) The lower external articular artery takes its course outwards, under 

 cover of the outer head of the gastrocnemius in the first instance, arid 

 afterwards under the external lateral ligament of the knee and the tendon 

 of the biceps muscle, passing above the head of the fibula. Having reached 

 the fore part of the joint, it divides near the patella into branches, some of 

 which communicate with the lower articular artery of the opposite side, and 

 with the recurrent branch from the anterior tibia! ; whilst others ascend, 

 and anastomose with the upper articular arteries. 



In this manner the four articular branches form at the front and sides of 

 the knee-joint a close network of vessels. 



Fig. 303. 



Fig. 303. ANTERIOR VIEW OP THE DEEP ARTERIAL 

 BRANCHES SURROUNDING THE KNEE-JOINT AND THEIR 

 ANASTOMOSES (from Tiedemann). \ 



a, the patellar articular surface of the femur ; 5, the 

 posterior or cartilaginous surface of the patella which, 

 with the ligamentum patellae, has been turned down ; c, 

 the head of the fibula ; 1, and 2, branches of the internal 

 superior articular branch of the popliteal ramifying on 

 the periosteum, and anastomosing with the external 

 superior articular branch 3, and with other arteries 

 within and below the joint; 4, branches of the internal 

 inferior articular ; 5, external inferior articular ; 6, re- 

 current of the anterior tibial artery. 



(e) The middle or azygos articular artery, is a 

 small branch which arises opposite the flexure of 

 the joint, and, piercing the posterior ligament, 

 supplies the crucial ligaments and other structures 

 within the articulation. 



PECULIARITIES. Deviations from the ordinary condi- 

 tion of the popliteal artery are not frequently met with. 

 The principal departure from the ordinary arrangement 

 consists in its high division into terminal branches. 

 Such an early division has been found to take place most 

 frequently opposite the flexure of the knee-joint, and not higher. 



In a few instances, the popliteal artery has been seen to divide into the anterior 

 tibial and peroneal arteries the posterior tibial being small or absent. In a single 

 case, the popliteal artery was found to divide at once into three terminal vessels, viz., 

 the peroneal and the anterior and posterior tibial arteries. 



The azygos articular branch frequently arises from one of the other articular 



G G 2 



