The Region of the Shoulder. 29 



wards, partly from mechanical causes and partly from the 

 contraction of the pectoralis major, with the result that 

 the subcoracoid displacement is produced. 



Symptoms of Dislocation. In each variety of dis- 

 location the following symptoms are present : 1. Flatten- 

 ing of the shoulder. If the ringer of the surgeon be pass- 

 ed downwards from the acromion, in examining a normal 

 arm, it comes in contact with the greater tuberosity. This, 

 along with the head of the bone beneath the deltoid, forms 

 the graceful outline of the prominence of the shoulder. 

 In dislocation, however, with the head absent from its 

 normal position, the finger feels a marked depression be- 

 low tihe acromion. 2. The elbozu is abducted, i.e., raised 

 from the side, and the patient cannot voluntarily press it 

 inwards so as to touch his side, and if the surgeon alt- 

 tempts it, it springs out again. This is due to the tension 

 of the deltoid, the supra-spinatus and ,the untorn part of 

 the capsular ligament, since in each variety these struc- 

 tures are put on the stretch. In addition to .the above, we 

 find, in the subglenoid form, other muscles more or less 

 affected, such as the subscapularis and the infra-spinatus, 

 which are overstretched and tense ; the biceps is rigid, 

 thus producing flexion with supination of the forearm, or 

 it may possibly be torn out of the groove, increasing-, 

 therefore, the present deformity and interfering with the 

 future usefulness of the arm ; while the teres major, teres. 

 minor and the latissimus dorsi are more or less relax- 

 ed. In the subcoracoid dislocation the deltoid, supra-spi- 

 natus and biceps are as tense as in the subglenoid, and tihe 

 additional structures affected would be the subscapularis, 

 pushed up and tense, or possibly wrenched from the lesser 

 tuberosity; while the infra-spinatus and the teres minor 

 are overstretched. The axillary nerves and vessels are 

 more liable to be injured in this form than in either of the- 



