The Muscles 59 



86. Muscles of the Head and Neck. There are scores 

 of tiny muscles about the head, face, and eyes, which by 

 their alternate contractions and relaxations impart to the 

 countenance those expressions which reflect the feelings 

 and passions of the individual. 



Two important muscles, the temporal, near the temples, 

 and the masseter, or chewing muscle, are the chief agents 

 in moving the lower jaw. They are very large in the lion, 

 tiger, and other flesh-eating animals. On the inner side of 

 each cheek is the buccinator, or trumpeter's muscle, which 

 is largely developed in those who play on wind instruments. 

 Easily seen and felt under the skin in thin persons, on 

 turning the head to one side, is the sterno-cleido-mastoid 

 muscle, which passes obliquely down on each side of the 

 neck to the collar bone. This muscle is prominent in 

 sculpture and painting. 



Experiment 23. To ilhistrate how the muscles use the bones as 

 levers. First, practice with a ruler, blackboard pointer, or any other 

 convenient object, illustrating the different kinds of levers, until the 

 principles are familiar. Next, illustrate these principles on the per- 

 son, by making use of convenient muscles. Thus, lift a book on the 

 toes, by the fingers, on the back of the hand, by the mouth, and 

 in other ways. 



Experiment 24. With the head slightly bent forward, grasp 

 between the fingers and thumb of the right hand the edge of the 

 left sterno-cleido-mastoid muscle, just above the collar bone. Raise 

 the head and turn it from left to right, and the action of this 

 important muscle is readily seen and felt. 



87. Muscles of the Chest and Back. The chest is sup- 

 plied with numerous muscles which move the ribs up and 

 down in the act of breathing. A great fan-shaped muscle, 

 called the pectoralis major, lies on the chest. It extends from 

 the chest to the arm and helps draw the arm inward and 



