QUADRICEPS EXTENSOR CRURIS. 



to beyond the middle of the thigh. From this the fleshy fibres spring pinnately, and, 

 passing downwards and backwards as they diverge, they end on the inferior tendon, 

 which extends over the lower two-thirds of the posterior surface of the belly. The 

 lower tendon becomes free about three inches above the patella, and forms a flat band 

 which is attached to the upper border of that bone, being joined with the tendons. 



Fig. 253. DEEP MUSCLES OF THE FRONT OF TUB 

 THIGH. (Allen Thomson.) 



a, anterior superior, and 6, anterior inferior spine of the 

 ilium ; c, great trochanter ; d, symphysis pubis ; e, pa- 

 tella ; /, inner side of the knee-joint ; g, head of the fibula ; 

 1, gluteus medius ; 2, gluteus minimus; 3, upper tendon 

 of the rectus, dividing into its two portions ; 4, points to 

 the cut tendon of insertion of the ilio-psoas muscle ; 5, 

 part of the obturator externus and quadratus femoris ; 

 <i, pectineus ; 7, adductor brevis ; 8, adductor magnus ; 

 9, vastus internus ; 10, crureus ; 11, vastus externus ; 

 12, lower tendon of the rectus ; 13, lower part of the ilio- 

 tibial band of the fascia lata. 



of the deeper portions of the quadriceps, and 

 forming with them the common tendon of 

 insertion. 



According 1 to W. R. Williams the posterior or " re- 

 flected " head of the rectus is the main tendon, and 

 the anterior or " straight " head is a secondary attach- 

 ment formed by a thickening- of the fascial investment 

 and appearing- only in the last months of foetal life. 

 ( i; The Anatomy of the Quadriceps Extensor Cruris," 

 Journ. Anat., xiii.) 



&. The vastus externus lias a narrow origin 

 from the femur, along the upper half of the 

 anterior intertrochanteric line, the fore and outer 

 parts of the root of the great trochanter, the 

 outer side of the gluteal ridge and the upper 

 half of the linea aspera, and to a slight extent 

 also from the external intermuscular septum. 

 The origin takes place for the most part by 

 a strong aponeurosis, which extends over the 

 surface of the muscle for the upper two-thirds 

 of its length. The fleshy fibres spring from 

 this aponeurosis, and some deeper ones also 

 from the bone immediately beneath it, and are 

 directed downwards and forwards to end on the 

 aponeurosis of insertion, which occupies the deep 

 surface and anterior border of the mass in its 

 lower half, and is continued down to the outer 

 part of the upper border of the patella, joining 



the other portions in the common tendon, and sending also an expansion downwards 

 to the capsule of the knee-joint. A few of the superficial fibres join the outer border 

 of the rectus tendon, and its deep surface is connected to a greater or less extent 

 with the subjacent crureus, especially in its lower parti 



c and d. The remaining portions of the muscle, viz., the vastus internus and 

 crureus, appear at first sight to be inseparably united and to form one mass. If, how- 

 ever, the rectus tendon be turned well downwards, there comes into view, above the 

 patella, a narrow interval which can be followed up between the two tendons in the 



