7*8 ELEMENTARY BIOLOGY. [CHAP. 



" powerful tendon, into the back of the head of the 

 femur. 



b. The ileo-psoas: it arises from the internal surface 

 of the posterior end of the ilium and is inserted 

 into the upper and outer border of the shaft of 

 the femur, immediately above the lesser slip of 

 the biceps. 



c. The pyriformis. This arises from the hinder end 

 of the urostyle and, passing inside the vastus ex- 

 ternus and biceps femoris, is inserted into the 

 shaft of the femur. 



d. The adductor brevis (cf. § 3. d.); a small muscle 

 lying immediately beneath c. 



e. The adductor magnus (cf. § 3. a.); a fleshy mass 

 lying immediately beneath the semimembran- 

 osus. 



6. The rotator muscles of the femur. 



Pin the whole down on one side, and remove all 

 the muscles hitherto examined with the exception of 

 the gluteus (5. a.), leaving their cut ends. Turn 

 these well back, noting their relations; there will 

 thus be laid bare : — 



a. The gluteus (cf. supra); its whole course can now 

 be followed. 



b. The quadratus femoris, arising from the postero- 

 dorsal border of the ilium and inserted into the 

 posterior upper border of the shaft of the femur, 

 side by side with the pyriformis (5. c). 



c. The obturatorius : this is best seen on reflection 

 of b. It arises from the postero-ventral area of 

 the hip-girdle to which it is closely applied; its 



