CHAPTER VII 

 MUSCLES OF THE EXTREMITIES 



The muscles of the extremities are frequently named for their 

 use, and they may all be grouped according to their action; as 

 flexors, to bend the joints over which they pass, and extensors to 

 straighten them; pronators and supinators; abductors and adduc- 

 tors; and rotators, inward or outward. Their origins are not only 

 from bones, but from fascia, and the fibrous septa between them. 

 This is true of most muscles to some extent, but particularly so 

 in the extremities. 



The principal bony attachments only are given here. 



MUSCLES OF THE UPPER EXTREMITY 



SHOULDER MUSCLES 



Supraspinatus. On the dorsal surface of the scapula. Origin. 

 The supraspinous fossa, the tendon passing over the head of the 

 humerus to the insertion on the top of the greater tubercle. 



Action. It lifts the arm away from body (abduction). 



Infraspinatus. Also on the dorsal surface of the scapula. 

 Origin. The infraspinous fossa. Insertion. The greater tu- 

 bercle of the humerus (below the supraspinatus). 



Action. It rotates humerus outward (the palm turns forward) . 



Nerve, both muscles. Suprascapular. 



Teres minor. Origin. The axillary border of the scapula. Insertion. 

 The greater tubercle, just below the infraspinatus. 



Action. It rotates humerus outward (palm turns forward). 



Nerve. A xillary. 



Teres major. Origin. Near the ' inferior angle of the scapula (on 

 axillary border.) Insertion. The shaft of the humerus (crest of lesser tuber- 

 cle), joining the tendon of the latissimus dorsi and acting with it (Fig. 84). 



Action. It draws the arm backward, and rotates it inward (the palm 

 turns backward}. 



Nerve. Subscapular (lower). 



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