STUDY OF THE MUSCLES. 65 



4. Measure the circumference of the forearm 



when the hand is open, and again when 

 it is tightly closed. Record your results. 

 Compare amount of increase with fig- 

 ures for biceps. 



5 . Pull up your sleeve. Flex the fingers several 



times i and note the movements of the 

 tendons in the wrist. Along what bones 

 do these tendons pass? 



D. The extensor muscles of the fingers. 



1. Straighten back the fingers as far as pos- 



sible, and by feeling of the back of the 

 forearm locate the belly of the extensor 

 muscles of the fingers. 



2. Move the middle finger alone. Describe 



the movements of the tendons on the 

 back of the hand. What do you con- 

 clude? 



3. Flex the middle finger of each hand until it 



touches the palm of the hand; place the 

 two hands together (palms facing) so 

 that the tips of the forefingers, fourth 

 fingers, and little fingers touch, pressing 

 the backs of the middle fingers closely 

 together. Try to separate each of the 

 pairs of fingers, still keeping the middle 

 fingers pressed together. Explain re- 

 sult. (See 2 above.) 



E. The muscles which move the ankle. 



i. Stand on tiptoe and locate in the calf of the 

 leg the belly of the extensor muscles of 

 the foot which cause this movement. To 



