The Region of the Shoulder. 3 1 



Signs of Dislocation. Signs of Fracture of Neck of Scapula. 



Flattening" below acromion. Flattening- below acromion. 



Head felt in axilla or elsewhere. Head felt in axilla. 

 Arm held directly or obliquely " Arm hang's vertically. 



outward. 



Dugas' sig-n holds g-ood. Dugas' sign does not hold good. 



Straight edge touches acromion. Straight edge touches acromion. 

 No bony crepitus. Bony crepitus. 



When reduced remains in position. When reduced is spontaneously 



displaced when unsupported. 

 Coracoid process normal position. Coracoid moves separately from 



scapula. 



The rent in the capsule is generally at the lower and 

 anterior part, as above mentioned, although Hamilton 

 states that in subspinous -dislocations the head of the bone 

 may leave the cavity, posteriorly, between the infra-spina- 

 tus and the teres minor. 



Atrophy of Deltoid Muscle. Impaired action of 

 .the arm may be caused by atrophy of the deltoid muscle, 

 the result of injuries to the circumflex nerve from blows, 

 falls, etc., or from pressure and laceration by the head of 

 the bone in dislocation. In the former instance, it may be 

 subsequent to a blow or fall, directly injuring the circum- 

 flex .nerve, where it winds around the humerus, or causing 

 inflammation and swelling of the muscle, which would 

 compress the nerve ; in the latter, it would be due to the 

 head of the bone pressing directly on the nerve. It is 

 worthy of note that the joint, the muscle chiefly affecting 

 the joint, i.e., the deltoid, and the skin over it, .have a com- 

 mon nerve supply, viz., the circumflex. This relationship 

 holds good also for the ,supra-acromial nerve, which sup- 

 plies the skin over the upper part of the deltoid muscle, 

 since the fourth cervical forms the supra-acromial, and 

 the fourth sends filaments through the fifth to the circum- 

 flex nerve. 



