592 APPENDIX 



leg and flexor of shank. Directly beneath the biceps femoris ob- 

 serve the large nerve, the sciatic. 



Along the front edge of the thigh and on its inner surface is the 

 sartorius or tailor's muscle. Extensor of shank, adductor of leg, 

 and rotator of leg. 



The entire mass of muscle in front of the femur after the sartorius 

 has been removed is the quadriceps femoris. Extensor of shank. 



On the inner surface of the thigh toward the back is the gracilis. 

 Adductor of leg. 



On the inner surface of the thigh after the removal of the gracilis 

 appear the following muscles from front to back. Small adductor 

 longus. Adductor of leg. The larger triangular adductor femoris. 

 Extensor of thigh. Large flat semi-membranosus. Extensor of 

 thigh. 



After dissection of above muscles there remains on the thigh 

 only the semi-tendinosus. Flexor of shank. 



The great mass of muscle forming the calf consists of three 

 muscles, the plantaris, gastrocnemius t and soleus. Do not try to 

 separate these. The tendo achilles is their common tendon. Ex- 

 tensor of foot. 



After removing above muscles there will be found against the 

 shank bones at the back the flexor longus digitorum. Flexor of toes. 



Along the front of the shank, a superficial muscle with its tendon 

 toward the inner side, is the tibialis anterior. Flexor of foot. 



Partly underneath the above, with its tendon toward the outer 

 side, is the extensor digitorum longus. Extensor of toes. 



The Contraction of Muscles. The tissues of cold-blooded ani- 

 mals are well suited for studies of function since they survive 

 sometimes for hours, the general death of the animal. 



From the hind leg of a recently killed frog make a femur-gastn 

 nemius preparation. This preparation is used for the study 

 muscular contraction. 



To study muscular contraction adequately the motions of th< 

 muscle must be magnified and must be recorded. For obtaining 

 magnified record of its movements the muscle is fastened in 

 clamp and its tendon attached to the short arm of a lever, whos 

 long arm presses lightly at its tip against a smoked paper on whicl 

 every movement of the muscle is recorded as a line (p. 94). T( 

 avoid superposing separate tracings the smoked paper is mounl 



