DISLOCATION OF THE ARM. 



53 



Fig. 10. 



immobility ; the elbow 

 stands out from the 

 body ; there is a hoi- 

 low under the acro- 

 mion process, and a 

 prominence in the 

 axilla. 



In dislocation back- 

 ward, which is most 

 rare, the elbow is in- 

 clined inward and for- 

 ward, the head of the 

 bone forms a promi- 

 nence beneath the 

 spine of the scapula, 

 and there is a hollow 

 beneath the acromion, 

 together with rigidity 

 and immobility. 



Violence and con- 

 traction of the mus- 

 cles pectoralis major, 



latissimus dorsi, teres major, and deltoid, are the causes of disloca- 

 tion of the arm. The immediate injury is a laceration of the capsule, 

 contusion of the muscles, and effusion of blood, and often paraly- 

 sis of the deltoid muscle from compression of the axillary nerve. 

 Unless reduction is effected the parts become united by adhesions, — 

 after which reduction cannot be produced without danger of lacerating 

 the artery. 



Fig. 11. 



