68 



ANATOMY FOR NURSES. 



[Chap. VI. 



The deltoid is a coarse triangu- 

 larmuscle which gives the rounded 

 outline to the shoulder; it extends 

 downwards and is inserted into 

 the middle of the sliaft of tlie 

 humerus. It raises the arm from 

 the side so as to bring it at right 

 angles to the trunk. 



The biceps is a long fusiform 

 muscle, occupying the whole of 

 the anterior surface of the arm; 

 it is divided above into two por- 

 tions or heads, from which cir- 

 cumstance it has received its 

 name. It arises by these two 

 heads from the scapula, and is 

 inserted into the radius. It flexes 

 and supinates the forearm on the 

 arm. 



The triceps is situated on the 

 back of the arm, extending the 

 whole length of the posterior sur- 

 face of the humerus. It is of 

 large size, and divided above into 

 three heads; hence its name. It 

 is inserted into the ulna. It is 

 the great extensor muscle of the 

 forearm, and is the direct antago- 

 nist of the biceps. 



The muscles covering the fore- 

 arm are disposed in groups, the 

 pronators and flexors being placed 

 on the front and inner part of the 

 forearm, and the supinators and 

 extensors on the outer side and 

 back of the forearm: they antag- 

 onize one another. The prona- 

 FiG. 59. — Muscles in Fnofir of i r i i j 



Forearm. (52, pronator teres ; 63, (55, torS turn the palm ot the hand 



^^ I'!' i'^^^^'"!' 70, .supinator lonsus; fo^vvards, and, when the elbow 



71, 77, 78, extensors; a, annular liga- ' 



ment. is flexed, downwards or prone. 



