442 A MANUAL OF ANATOMY 



close above the femoral opening, descends at first upon the inner 

 side of the popliteal artery, and then in front of it as low as the 

 origin of the central or azygos artery, where the nerve leaves the 

 main vessel and passes, with that branch, through the posterior 

 ligament of the knee-joint to the interior of the articulation. 



Branches. — ^The branches are (i) muscular and cutaneous, and 

 (2) articular. 



The muscular and cutaneous branches are divided into a superior 

 and an inferior set. 



The superior set are purely muscular, and are distributed 

 to the lower parts of the hamstring muscles. They anastomose 

 with the lower two perforating branches of the arteria profunda 

 femoris. 



The inferior or sural set are partly muscular and partly 

 cutaneous. The muscular branches supply both heads of the 

 gastrocnemius and the plantaris. The cutaneous branches are 

 three in number, and supply the integument over the upper half 

 of the calf. The middle cutaneous branch lies in the groove between 

 the two heads of the gastrocnemius with the external or short 

 saphenous vein. This branch is sometimes of large size, and in 

 these cases, under the name of the external saphenous artery, it 

 descends to the back of the external malleolus. 



The articular branches are five in number — two superior, external 

 and internal, one central or azygos, and two inferior, external and 

 internal. 



The superior external articular artery courses outwards close 

 above the external condyle of the femur, passing beneath the 

 biceps femoris and through the external intermuscular septum into 

 the crureus muscle, where it breaks up into branches. These 

 anastomose with the following arteries : (i) descending branch 01 

 the external circumflex ; (2) inferior external articular ; (3) deep 

 branch of the anastomotica magna ; (4) superior internal articular ; 

 and (5) fourth or lowest perforating branch of the arteria profunda 

 femoris. 



The superior internal articular artery courses inwards close 

 above the internal condyle of the femur, and, having passed 

 beneath the tendon of the adductor magnus, it enters the vastus 

 internus, where it divides into branches. These anastomose with 

 the following arteries : (i) inferior internal articular ; (2) deep 

 branch of the anastomotica magna ; and {3) superior external 

 articular. 



The central or azygos articular artery, if a separate branch, 

 arises from the front of the main artery, but it is often a branch 

 of the superior external articular. It passes through the posterior 

 ligament of the knee-joint to supply the synovial membrane and 

 ligaments within the joint. 



The inferior external articular artery courses horizontally out- 

 wards beneath the tendon of the biceps femoris and the long 

 external lateral ligament of the knee-joint to the outer side of the 



