132 ELEMENTS OF PHYSIOLOGY 



The muscles of the trunk are and . 



The muscles of the limbs are and . 



2. Grasp your arm above the elbow and bend it. What 

 changes do you feel ? 



3. Span the biceps, holding tip of finger in elbow and 

 thumb farther up the arm. About how many inches of its 

 length does the biceps lose by contracting? 



4. What muscles are attached to the bones without ten- 

 dons ? (Examine figures in book; also think of meat you 

 have eaten.) 



5. Why -is round steak usually the toughest steak ? the 

 most nutritious ? 



6. Why is a fowl's leg dark meat although its breast is 

 white ? Why is a fowl's breast white and a dove's breast 

 dark ( 207, 220)? 



7. Why does practicing looking cross-eyed have a tend- 

 ency to make one so ? (Give effect on both nerve and 

 muscle.) 



8. Where are the muscles that bend the fingers ? 



9. Name the places in the body where the tendons can 

 be most easily felt while the muscles are working. 



223. How the Nerves and Muscles cooperate. How 

 many ways of exciting the contractility of a muscle have 

 you learned ? When the food enters the stomach, the 

 mechanical stimulus starts impulses along the nerve to 

 the ganglion, and reflex impulses cause the involuntary 

 muscles in the walls of the stomach to contract. When 

 we desire to make a certain movement, an impulse is 

 sent from the brain along a nerve to the muscle which 

 performs this movement. This impulse sets the muscle 

 engine going somewhat as an electric current sent by 

 pressing .a button starts a bell to ringing or a machine to 

 running. 



224. The muscular tissue is composed chiefly of albu- 

 minous material. It has been found that increased muscular 



