Chap. 9 PROTECTION, SUPPORT, AND MOVEMENT SKELETONS 



151 



Stflrnoclgidomostoid i 



/ 



Tropezius — ^ 



Temporol 



Massefer 



Extensors ': jl 

 of 

 fingers 



Gluteus 



moximus, 



Tendons 



Flexor of hond 



Rectus obdominus 

 External oblique 



ist ligoment 



Broad fascio of leg 



> Quodnceps 



Biceps 



Fig. 9.16. Principal muscles of the human body. The names and uses of the 

 muscles are given in Table 1. (Courtesy, Etkin: College Biology. New York, 

 Thomas Y. Crowell & Co., 1950.) 



lifted. Human clavicles stand out like slender bridges from shoulder to sternum, 

 easily broken and dislocated. The whole shoulder girdle is turned and shifted 

 in playing a piano, washing windows, driving a car. Clavicles are often re- 

 duced or lacking, as in cats and some other mammals that run and pounce, 

 in horses that run, and in deer that leap. 



The radius and ulna of the forearm, chiefly the ulna, articulate with the 

 humerus at the elbow in a hinge joint. The upper end of the ulna is called the 

 funny bone or crazy bone, because of the sharp pain which occurs when it is 

 struck. This is due to the stimulation of the ulnar nerve which passes over a 

 knob or condyle on the end of the humerus. At their opposite ends the bones 

 o'' the forearm are jointed to the short wrist bones (carpals). Most of them 



