7 3 o ELEMENTARY BIOLOGY. [CHAP. 



y. The rectus femoris antiais : the middle divi- 

 sion of the triceps ; it arises from the pos- 

 terior part of the ventral border of the iliac 

 bone. For the insertion of the triceps femo- 

 ris, see 2. d. f]. 



b. The glutceus : this muscle arises from the hinder 

 two-thirds of the external surface of the ilium ; 

 it runs down between the vastus externus and 

 the rectus anticus to be inserted into the back 

 of the head of the femur. 



c. The pyriformis. This arises from the posterior 

 part of the urostyle and, passing inside the 

 vastus externus, is inserted into the shaft of the 

 femur. 



d. The biceps femoris : a long thin muscle, lying 

 along the inner side of the vastus externus ; it 

 arises from the iliac bone above the acetabulum ; 

 below it divides into two pieces, one of which 

 is inserted into the middle of the shaft of the 

 femur, while the other ends in a rounded tendon 

 which is inserted into the back of the distal end 

 of the same bone. 



e. The semimembranosus : a large muscle inside the 

 biceps ; it arises from the upper posterior part 

 of the iliac symphysis and is inserted into the 

 aponeurosis round the knee-joint. 



Lying deep in the thigh, between the biceps 

 and semimembranosus muscles, will be seen the 

 femoral vessels and the sciatic nerve. 



f. Divide and reflect the vastus externus and the 

 biceps : beneath them will be laid bare 



