THE SHOULDER-GIRDLE. 



235 



follows the head without being detached from its connections. The subscapularis 

 muscle not infrequently has its lower edge torn. 



The brachial plexus and blood-vessels are pushed inward by the head, but when 

 the arm is abducted they are stretched over it, running close to the coracoid process. 



FIG. 247. Subcoracoid dislocation of the humerus, showing the position of the bones in relation to each other and 



to the soft parts. 



As the circumflex nerve winds around the surgical neck of the humerus, it may be 

 ruptured or tightly stretched over the head of the bone. 



Hyperabduction stretches the vessels and nerves so forcibly over the head just 

 prior to its leaving the socket as sometimes to produce serious injury to them. 



SIGNS AND SYMPTOMS. 



There is (i) at first elevation then lowering of the shoulder, (2) flattening of the 

 deltoid muscle, (3) projection of the elbow away from the side. (4) The normal 

 hollow below the outer third of the clavicle is filled up ; the head, covered by the deltoid, 

 may sometimes even make a rounded prominence at this point which can frequently be 

 felt. (5) If the elbow is raised and the hand placed on the opposite shoulder and held 

 there the elbow cannot be brought flat on the chest (Dugas's sign), (6) with the 



