MUSCLES 41 



Reflect the gracilis muscle. 



11. The Semitendinosus is the smaller and more 

 external of the two posterior muscles of the thigh. 

 It arises from the tuberosity of the ischium, and is 

 inserted by fascia on the inner side of the tibia, 

 and by tendon on the front of the tibia, just below 

 the patella. (Plates II., III., and IV.) 



12. The Semimembranosus is the larger of the 

 two posterior muscles of the thigh. Its origin is 

 on the ischium, from the tuberosity to the sym- 

 physis pubis. It is inserted (i) on and above the 

 inner condyle of the femur, and (2) by a strong 

 tendon on the internal tuberosity of the tibia. 

 (Plates II., III., and IV.) 



13. The Quadriceps Extensor is composed of four 

 large muscles which have separate origins but are 

 inserted on the tuberosity of the tibia by a com- 

 mon tendon, " the tendon of the patella." 



a. The vastus externus is the largest and most 

 external of the four divisions. Its origin is on 

 the whole outer surface of the shaft of the femur 

 and on the great trochanter. (Plate III.) 



b. The rectus femoris is the most anterior of 

 the four divisions, lying between the vastus ex- 

 ternus and the muscle next to be described, the 

 vastus internus. It arises from the ilium just 

 above the acetabulum. (Plate IV.) 



c. The vastus internus lies between the rectus 

 femoris and the sartorius. It arises from the in- 



