THE PRINCIPLES OF MYODYNAMICS. 89 



(4.) The extensors of the arm are the triceps 

 brachii, the posterior part of the deltoid, the 

 infraspinatus, the teres minor, the teres major, 

 the subscapularis, and the latissimus dorsi. 



(5.) The out-rotators of the arm are the teres 

 minor, the infraspinatus, the supraspinatus, and 

 the posterior part of the deltoid. 



(6.) The rota tors of the arm are the sub- 

 scapularis, the pectoralis major, the anterior part 

 of the deltoid, the teres major, and the latissi- 

 mus dorsi. 



(7.) The circiLindiLctors of the arm comprise, 

 in one way or another, all the muscles that span 

 the shoulder-joint and move the arm. 



82. In an average-sized specimen of an adult 

 humerus, the followino- measurements were 

 made : 



(i.) The entire length was about 13 inches. 



(2.) The length of the anatomical neck was 

 about three-eighths of an inch. 



(3.) The depth of the head was about five- 

 eighths of an inch. 



(4.) The diameter of the head was about one 

 and three-eighths inches. 



