3GG THE MUSCLES 



(a) Rectus Femoris 



The rectus femoris — named from its long straight course — is strong, fusiform, 

 and flattfiK'd from Ijefore backwards; it arises l)y an anterior and a posterior head. 



Origin. — Anterior head, from the front of the anterior inferior spine of the iUum; 

 posterior head, from the upper surface of the rim of the acetabuhnn just external to 

 the attachment of the capsular ligament. 



Insertion. — Tlie front of the upper border of the patella. 



Structure. — This muscle consists of two strong tendinous expansions joined by 

 fleshy fibres. The upper expansion is formed aliove by the union of the two 

 tendinous heads in a small arch, whicli is intimately connected with the capsule of 

 the hip-joint. From this arch the tendinous expansion descends upon the front of 

 the muscle as far as the middle of the thigh, getting thinner and narroAver as it 

 descends. The tendon of insertion begins upon the back of the muscle also al:)out 

 the middle of the thigh, and soon expands into a broad aponeurosis which covers 

 the back of the muscle at its lower end; about three inches (T'o cm.) above the 

 patella, it becomes free of muscular fibres, and forms a strong tendinous band which 

 is inserted into the upper border of the patella. The fleshy fil>res pass from the 

 back and sides of the upper expansion to the front and sides of the tendon of inser- 

 tion. Seen from the front, these fleshy fil^res appear to diverge on both sides from 

 the upper expansion, and, after passing round the border of the muscle, they 

 converge upon the tendon of insertion so as to give the muscle a bipenniform 

 appearance. 



Nerve-supply. — From the lumbar plexus (through the second, third, and 

 fourtli lumliar nerves), by the anterior crural nerve Avhich sends filaments to the 

 posterior aspect of the muscle in the upper half of its course. 



Action. — To assist in the powerful extension of the knee by the quadriceps. It 

 W'ill also help in flexion of the hip; and it Avill be a powerful agent in preventing 

 dislocation of the head of the femur. When the hip-joint is flexed, the muscle will 

 act chiefly from its posterior head; but when the hip is extended, the anterior head 

 of tlie nniscle will act with more power. 



Relations. — In front lie the sartorius, tensor vaginae femoris, and the fascia 

 lata; l)ehind. it lies on the hip-joint and the crureus muscle; upon its inner border 

 above is the iliacus; and outside it lie the gluteus medius and minimus. 



(b) Vastus Externus 



The vastus externus — named from its great size and its position upon the 

 outer surface of the thigh — is a thick rhomljoidal sheet. 



Origin. — (1) The upper half of the anterior intertrochanteric line and tlie front 

 of the upper part of the femur along the anterior Ijorder of the greater trochanter; 

 (2) a horizontal line which forms the loAver border of the greater trochanter; (3) the 

 outer lip of the gluteal ridge; (4) the upper half of the outer lip of the Hnea aspera 

 and the adjacent portion of the shaft of the femur for about one-sixth of an inch 

 (4 mm. ) ; (5) the external intermuscular septum in the neighl:)Ourhood of its attach- 

 ment to tlie linea aspera. 



Insertion. — (1) The outer half of the upper 1,)order of the patella. ])ehind 

 the preceding tendon, Avith which it also blends; (2) the u})i)er third of the 

 outer l:)order of the patella; (3) by an aponeurosis Avhich is inserted partly 

 into the front of the external tuberosity of the ti]>ia, partly into the deej) fascia 

 of the leg. 



Structure. — Arising partly directly from the bone, and partly by a strong apo- 

 neurosis Avhieh covers the outer surface of the muscle in its upper "tAvo-thirds, the 

 fleshy fibres run parallel to one another downAvards, forAA'ards, and iuAvards, at 

 the same time curving slightly as they pass over the rounded mass formed l>y the 

 crureus muscle. The aponeurosis of insertion lies upon the inner surface of the 

 muscle and receives fleshy fibres to Avitliin one inch (2-5 cm.) of its insertion into 

 the patella and its l)lending Avith tlie other tendons of the quadriceps muscle. Upon 

 its anterior surface it unites Avith tlie tendon of the rectus muscle, and ui)(>n its 

 posterior surface is received a ]iart of the insertion of the crureus. 



Nerve-supply. — From the anterior crural (through the second, tliinl. and 



