OUR BODIES AND HOW WE LIVE 



76. Some Muscles about the Shoulder and Chest. The 



large muscle on each side of the chest is fan-shaped, and 

 powerfully developed in strong men (pectoralis major). It 

 helps draw the arm inward and forward. 



The large, thick muscle covering the shoulder is thought 

 to resemble the Greek letter A (delta). A military officer 



2^.'#%; 



FIG. 42. Principal Muscles on the Left Side of the Neck. 



wears his epaulet over this muscle. The action of the 

 two-headed muscle (biceps) which bends the forearm, and 



the three-headed (triceps) which straightens it, is familiar 

 under the name of "trying your muscle." 



A three-sided muscle (trapezius) covers the shoulder 



blade, like a monk's hood, and helps move the shoulder. 



