612 



ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 



imperfect and irregular union. The muscles of 

 the dorsum scapulae were diminished, by being 

 thrown out of use, and the tendon of the long 

 head of the biceps muscle was entire, but 

 glued down by adhesion." Upon further ex- 

 amination of the scapula and os humeri, Sir 

 A. Cooper found the muscles and the situation 

 of the bones to be as follows: " The head 

 of the os humeri was placed behind the glenoid 

 cavity of the scapula, and rested upon the 

 posterior edge of that articular surface, and 

 upon the inferior costa of the scapula, where 

 it joins the articulation. When the scapula 

 was viewed anteriorly, the head of the os hu- 

 meri was placed in a line behind the acromion 

 but below it, and a wide space intervened be- 

 tween the dislocated head of the bone and the 

 coracoid process, in which the fingers sunk 

 deeply towards the glenoid cavity of the sca- 

 pula. When viewed posteriorly, the head of 

 the os humeri was found to occupy the space 

 between the inferior costa and spine of the 

 scapula, which is usually covered by the infra- 

 spinatus and teres minor muscles. The tendon 

 of the subscapularis muscle, and the internal 

 portion of the capsular ligament, had been 

 torn at the insertion of that muscle; but the 

 greater part of the posterior portion of the 

 capsular ligament remained, and had been 

 thrust back with the head of the bone, the 

 back part of which it enveloped. The supra- 

 spinatus muscle was put upon the stretch, the 

 subscapularis was diminished by want of ac- 

 tion, and the infra-spinatus, and teres minor 

 muscles were shortened and relaxed, as the 

 head of the bone carried their insertions back- 

 wards. The tendon of the long head of the 

 biceps muscle was carried back with the head 

 of the bone, and elongated ; but it was not 

 torn. As to the changes in the bones, the 

 head of the os humeri, and the outer edge of 

 the glenoid cavity of the scapula, were in di- 

 rect contact, the one bone rubbing upon the 

 other when the head of the os humeri was 

 moved ; and this accounted for the sensation 

 of crepitus at the early period of the disloca- 

 tion, as there was no fracture. The glenoid 

 cavity was slightly absorbed at its posterior 

 edge, so as to form a cup, in which the head of 

 the bone was received, and this latter bone and 

 the articular cartilage had been in some degree 

 absorbed where it was in direct contact with the 

 scapula, as well as changed by attrition during 

 the seven years the patient lived." The surface 

 of the original glenoid cavity, instead of being 

 smooth and cartilaginous, was rough and irre- 

 gular, having elevations at some parts, and 

 depressions at others. The extremity of the 

 acromion was sawn off, to look for any little 

 fragment of bone which might have been broken 

 off, but not the smallest fracture could be per- 

 ceived. 



Mr. Key, in his account of another case of 

 dislocation of the os humeri backward on the 

 dorsum of the scapula, writes as follows : 

 *' I found a very stout man sitting up in bed 

 in great pain, and complaining more than 

 patients commonly do under dislocation, and 

 1 concluded it to be some fracture about the 



cervix, especially as at first view nothing could 

 be seen of a hollow under the deltoid muscle, 

 the joint appearing round as usual. On pass- 

 ing to the man's side to examine the limb, the 

 deformity of the shoulder became visible, the 

 forepart appeared flattened, and the back of 

 the joint fuller than natural : the head of the 

 bone could be seen as well as felt, resting on 

 the posterior part of the cervix scapulae. The 

 elbow could be brought to the side, or raised 

 on a level, with the acromion. Rotation out- 

 wards was entirely impeded, in consequence of 

 the subscapularis being stretched, all motions 

 of the limb giving him extreme pain, which 

 was referred to the lower part of the deltoid 

 muscle, in the direction of the articular nerves, 

 which were probably injured by the pressure 

 of the head of the bone." 



The dislocation of the head of the hu- 

 merus backwards on the dorsum of the 

 scapula is said to be very easily recognised, 

 yet the writer has seen two examples of it 

 which had been overlooked at the moment of 

 the accident, and he has heard of two others. 

 When the swelling, the result of the lacera- 

 tion of parts, has subsided, the nature of the 

 injury becomes very evident indeed. A gentle- 

 man, Mr. A. F., aged about 35 years, called 

 upon the writer four years ago to examine his 

 shoulder. He stated that he was thrown off a 

 jaunting car about three months previously, 

 and injured his shoulder, and that ever since 

 he had had but very imperfect use of his arm. 

 The patient had been educated as a medical 

 man, had practised surgery, but did not him- 

 self suspect the nature of the injury, when, 



Fig. 440. 



Case of Mr. A. F. Dislocation of the head of the 

 humerus backwards on the dorsum of the scapula. 



about ten weeks after the accident, he called 

 upon the writer. The nature of the injury 



