EXTERNAL CIRCUMFLEX ARTERY. 159 



From the lower part of the vasti muscles a superficial aponeurotic expansion 

 expansion is derived : this prolongation, which is strongest on the m 

 inner side, is united with the fascia lata and the other tendinous 

 offsets to form a capsule in front of the joint, and is fixed below to 

 the heads of the tibia and fibula. 



Subcrureus muscle. Beneath the crureus, near the knee-joint, is a Small sub- 

 thin layer of pale fibres, which is but a part of the large muscle, musci? 

 separated from the rest by areolar tissue. Attached to the femur in ends on the 

 the lower fourth, and often by an outer and inner slip, it ends in synovia! 

 aponeurotic fibres on the synovial sac of the knee-joint. 



Action. All parts of the quadriceps extend the knee-joint when Use with 

 the tibia is moveable ; and the rectus can flex the hip-joint over abi?:" 10 

 which it passes. The fleshy bellies are strong enough to break the 

 patella transversely over the end of the femur, or to rupture some- 

 times the common tendon. 



With the tibia as the fixed point the vasti will bring forwards the with tibia 

 femur, and straighten the knee, as in rising from the stooping fi> 

 posture and in jumping. The rectus also will stay the pelvis on the 

 femur, or assist in moving it forwards in stooping. 



The subcrureus draws upwards the pouch of synovial membrane how sub- 

 above the patella in extension of the knee. acts. 6 " 8 



INTERMUSCULAR SEPTA. The processes of the fascia lata, which i n termus- 

 limit the extensor muscle laterally, are named external and internal, cular septa 

 and are fixed to the linea aspera and the lines leading to the condyles are two : 

 of the femur. 



The external septum is the stronger, and reaches from the insertion the outer 

 of the glutens maximus to the outer condyle of the femur. It is 

 situate between the vastus externus and crureus on the one side, 

 and the short head of the biceps on the other, to all of which it 

 gives origin : it is perforated near the outer condyle by the upper 

 external articular vessels and nerve. 



The inner partition is very thin along the side of the vastus the inner is 

 internus ; and its place is supplied by the strong tendon of the mdls 

 adductor magnus between the inner condyle and the linea aspera. 



The EXTERNAL CIRCUMFLEX ARTERY (fig. 59, 4 , p. 153) IS the chief External 



vessel for the supply of the muscles of the front of the thigh. It 



usually arises from the outer side of the deep femoral artery, 



but often from the common trunk. It is directed outwards 



through the divisions of the anterior crural nerve, and beneath the divides into 



sartorius and rectus muscles, and supplies offsets to those muscles. 



Its terminal branches are ascending, transverse, and descending : 



The ascending branch is directed beneath the tensor fasciae ascending, 

 femoris to the outer side of the hip, where it anastomoses with the 

 gluteal artery, and supplies the contiguous muscles. 



The transverse branch, the smallest, divides into two or three transverse, 

 which enter the vastus externus, and anastomose with the per- 

 forating arteries. 



The descendinq branch is the largest, and ends in pieces which are aud d- 



scendintr 



distributed to the crureus and vastus externus muscles. One con- branches, 

 siderable branch descends to the knee along the anterior border of 



