38 LABORATORY DIRECTIONS 



14. QuADRATUS Femoris. — ThIs is the most posterior of tiie 

 fan-like mass of muscles around the great trochanter. It 

 originates from a triangular area on the lateral surface of. the 

 ischium, near the posterior end, and inserts on the greater and 

 lesser trochanters of the femur. 



Action: to extend and rotate the thigh. 



15. Capsularis. — This is a small muscle entirely covered 

 by the gluteus minimus. It originates on the lateral surface 

 of the ilium near the acetabulum, and inserts on the femur distal 

 to the great trochanter. It may be seen by removing the gluteus 

 minimus at its insertion. It will be seen again when the quadri- 

 ceps femoris muscle is dissected. 



Action: to rotate the thigh. 



There now remain several muscles, the semitendinosus, the 

 semimembranosus, the adductor femoris, and the quadriceps 

 femoris, which show on both sides of the thigh, but are more 

 easily dissected from the medial side. Cut transversely through 

 the middle of the gracilis, if this has not already been done. 



16. Semitendinosus. — This is the long muscle forming the 

 caudal border of the thigh. The proximal end is on the lateral 

 side; the distal end is on the medial. It originates on the 

 posterior end of the ischium, and inserts on the proximal end of 

 the tibia by means of a tendon. 



Action: to flex the shank. 



17. Semimembranosus. — This is the thick muscle, with fibers 

 loosely held together, lying next to the semitendinosus. It 

 originates from the caudal border of the ischium and inserts on 

 the medial side of distal end of the femur and the proximal end 

 of the tibia. 



Action: to extend the thigh. 



18. Adductor Femoris.— This is a large triangular muscle 

 between the semimembranosus and the femur. The fibers are 

 loosely united, making it difficult to find the boundaries of the 

 muscle. The origin is from the lateral surface of the pubis and 

 ischium, near the symphysis, and from the tendon of the gracilis 

 muscle. The insertion covers almost the whole shaft of the 

 femur. 



Action: to extend and adduct the thigh. 



