Chap, xi.] REGION OF THE SHOULDER. 163 



front of the arm. A prominence is sometimes felt 

 about this joint in place of the level surface that it 

 should present. This is due to an enlargement of the 

 end of the clavicle, or to a thickening of the fibro- 

 cartilage sometimes found in the joint. In many 

 cases it has appeared to me to be due to a trifling 

 luxation upwards of the clavicle depending upon some 

 stretching of the ligaments. It is certain that the 

 dry bone seldom shows such an enlargement as to 

 account for this very common prominence at the 

 acromial articulation. The sternal end of the clavicle 

 is also, in muscular subjects, often large and unduly 

 prominent, and sufficiently conspicuous to suggest a 

 lesion of the bone or joint when none exists. 



The roundness and prominence of the point of the 

 shoulder depend upon the development of the deltoid 

 and the position of the upper end of the humerus. 

 The deltoid hangs like a curtain from the shoulder 

 girdle, and is bulged out, as it were, "by the bone 

 that it covers. If the head of the humerus, there- 

 fore, be diminished in bulk, as in some impacted 

 fractures about the anatomical neck, or be removed 

 from the glenoid cavity, as in dislocations, the 

 deltoid becomes more or less flattened, and the acro- 

 mion proportionately prominent. The part of the 

 humerus felt beneath the deltoid is not the head, 

 but the tuberosities, the greater tuberosity externally, 

 the lesser in front. A considerable portion of the 

 head of the bone can be felt by the fingers placed 

 high up in the axilla, the arm being forcibly abducted 

 so as to bring the head in contact with the lower 

 part of the capsule. The head of the humerus faces 

 very much in the direction of the internal condyle. 

 As this relation, of course, holds good in every 

 position of the bone, it is of value in examining 

 injuries about the shoulder, and in reducing disloca- 

 tions by manipulation, the condyle being used as 



