THE LOWER LIMB 4^7 



Insertion. — The anterior part of the upper border of the patella 

 by a flat tendon, which is free from fleshy fibres in its lower 

 3 inches. 



Nerve-supply. — ^The posterior division of the anterior femoral 

 nerve, the branch from which furnishes an offset to the hip-joint. 



Action. — (i) The muscle is a powerful extensor of the knee-joint ; 

 and (2) it is a flexor of the hip-joint. In extending the knee-joint 

 the rectus femoris acts entirely from its anterior or straight head 

 when the hip- joint is extended ; but, when the hip- joint is flexed^ 

 the muscle in extending the knee-joint acts from its posterior or 

 reflected head. 



The fibres which form the fleshy belly are very short, and, spring- 

 ing in a bipenniform manner from the common tendon of origin, 

 they pass obhquely to end upon the tendon of insertion as low 

 as a point 3 inches above the patella. This arrangement gives the 

 muscle great power of action, but hmited range of movement. 

 Superiorly the muscle is related to the capsular Ugament of the 

 hip- joint. 



2. Vastus Externus — Origin. — (i) The upper third of the anterior 

 intertrochanteric line of the femur ; (2) the anterior and inferior 

 borders of the great trochanter ; (3) the outer side of the gluteal 

 ridge ; (4) the outer hp of the linea aspera in its upper half ; (5) the 

 adjacent portion of the shaft of the femur ; and (6) the upper part 

 of the external intermuscular septum. 



Insertion. — (i) The outer half of the upper border of the patella 

 posterior to the rectus femoris ; (2) the upper third of the outer 

 border of the patella ; and (3) very shghtly into the outer border 

 ^of the tendon of the rectus femoris. 



Nerve-supply. — The posterior division of the anterior femoral 

 nerve, the branch from which furnishes an offset to the knee-joint. 



The vastus externus at its origin is aponeurotic, and the aponeurosis 

 spreads downwards upon the superficial surface of the muscle 

 for a considerable distance. The fibres are directed downwards and 

 forwards or inwards. The anterior border is free. 



3. Crureus — Origin.^i) The lower two-thirds of the anterior 

 intertrochanteric line ; (2) the anterior and external surfaces of the 

 shaft of the femur over about their upper three-fourths ; (3) the 

 outer lip of the linea aspera in its lower half ; (4) the upper two- 

 thirds of the external supracondylar ridge, as well as the immediately 

 adjacent portion of the bone ; and (5) the contiguous part of the 

 external intermuscular septum. 



Insertion. — ^The inner half of the upper border of the patella 

 behind the rectus femoris, where it has many of the fibres of the 

 vastus intemus associated with it. 



Nerve-supply. — The posterior division of the anterior femoral 

 ner\'e, the branches from which are two or three in number. The 

 most internal of these branches furnishes an offset to the knee- 

 ijoint, which in its course supplies the subcrureus muscle. 

 ! The direction of the fibres of the crureus is chiefly downwards. 



