572 DISSECTION OF THE THIGH. 



some few scattered aponeurotic fibres passing over the cutaneous surface, 

 but none being continued over the articular surface of the bone. (See 

 Ligament of the Patella.) 



From the lower part of the muscle a superficial aponeurotic expansion 

 is derived : this prolongation, which is strongest on the inner side, is 

 united with the fascia lata and the other tendinous offsets to form a cap- 

 sule in front of the joint, and is fixed below to the heads of the tibia and 

 fibula. 



Subcrureus muscle. Beneath the strong fibres of the vastus, near the 

 knee joint, is a thin layer of pale fibres, which is but a part of the inner 

 vastus, separated from the rest by areolar tissue. Attached to the femur 

 in the lower fourth, and often by an outer and inner slip, it ends in apo- 

 neurotic fibres on the synovial sac of the knee joint. 



Action. All three heads of the triceps extend the knee joint, when the 

 tibia is movable ; and the rectus can flex the hip joint over which it passes. 

 The fleshy bellies are strong enough to break the patella transversely over 

 the end of the femur, or to rupture sometimes the common tendon. 



When the tibia is fixed the vasti will bring forwards the femur, and 

 straighten the knee, as in walking or standing ; and the rectus will prop 

 the pelvis on the femur, or assist in moving it forwards in stooping. 



The subcrureus contracts in extension of the knee, and elevates the 

 synovial membrane above the patella. 



Inter muscular septa. The processes of the fascia lata, which limit 

 laterally the extensor muscle of the knee, are thus named, and are fixed to 

 the linea aspera and the lines leading to the condyles of the femur. 



The external septum is the strongest, and reaches from the outer condyle 

 of the femur to the insertion of the gluteus maximus. It is situate between 

 the vastus internus and externus on the one side, and the short head of the 

 biceps on the other, to which it gives origin ; and 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 internus ; 

 and its place is supplied by the strong tendon of the adductor niagnus be- 

 tween the inner condyle and the linea aspera : the internal articular ves- 

 sels are transmitted through it to the front of the knee joint. 



The EXTERNAL CIRCUMFLEX ARTERY (fig. 197, 4 ) is the chief vessel 

 for the supply of the muscles of the front of the thigh. It arises from the 

 outer side of the profunda (deep femoral) artery, but often from the femoral 

 trunk. It is directed outwards through the divisions of the anterior crural 

 nerve, and beneath the sartorius and rectus muscles to the outer part of 

 the thigh, where it ends in branches. Offsets are given from it to the 

 rectus and sartorius ; and its terminal muscular branches consist of ascend- 

 ing, transverse, and descending : 



The ascending branch is directed beneath the tensor vaginae femoris to 

 the back of the hip bone, where it anastomoses with the gluteal artery, 

 and supplies the contiguous muscles. 



The transverse, the smallest in size, divides into two which perforate 

 the vastus externus, and anastomose with arteries on the back of the thigh. 



The descending branch is the largest, and ends in pieces which are dis- 

 tributed to the vasti muscles. One considerable branch enters the outer 

 part of the vastus internus, and reaching the knee, anastomoses on this 

 joint with the external articular arteries ; a small offset courses over the 

 muscle with a nerve to the joint. 



The ANTERIOR CRURAL NERVE (fig. 197, 8 ) of the lumbar plexus (p. 



