608 



ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 



parts, executed upon the spot, by a distin- 

 guished artist. On removing the integuments 

 of the axilla, the cellular membrane, which 

 was extensively ecchymosed, formed a kind of 

 cap, closely embracing the head of the os 

 humeri, which, when the axilla was cleared, 

 was seen lodged on the inferior costa of the 

 scapula, or rather, on its neck ; the head of the 

 bone, in escaping from its socket, had pushed 

 the teres minor downwards, and burst through 

 the lower part of the subscapularis muscle, some 

 of the fibres of which closely embraced the 

 neck of the bone, while the bulk of the us- 

 cle was pushed upwards, and detached from 

 the inner surface of the scapula (Jig. 434-.). 



Fig. 434. 



Axillary dislocation ; recent case. (After Sir P. 

 Crampton.) 



The neck of the humerus, therefore, was in 

 some degree embraced by the divided fibres of 

 the subscapularis muscle, while a portion of 

 its head rested on the neck and part of the 

 venter of the scapula, without the interven- 

 tion of any muscular substance. The short 

 head of the biceps, and the coraco-brachialis, 

 were forced to describe a curve outwards, 

 over the neck of the humerus on the sternal 

 side, while the long head of the triceps crossed 

 the neck of the bone obliquely on the dorsal 

 side ; this strangulation of the head of the 

 bone, by the surrounding muscles, was made 

 most apparent when extension was applied 

 to the fore-arm. The biceps and triceps 

 seemed then to close behind the head of the 

 bone, and interpose themselves between it. 

 and the glenoid cavity ; the tendon of the 

 long head of the biceps remained in its groove, 

 but the sheath in which it runs was partially 

 ripped up. The capsular ligament was com- 

 pletely torn from the lower part of the neck 

 of the humerus, to the extent of more than 

 half its circumference, the torn edge appear- 

 ing like a crest over the head of the bone. 

 The great nerves and blood vessels of the arm 

 were forced to describe a curve backwards, 

 by the pressure of the head of the bone, which 



was in contact with them. But the greatest 

 injury had been sustained by the 'articular 

 muscles] as the} 1 have been called, which lie on 

 the back of the scapula. The tendons of the 

 supra-spinatus, the infra-spinatus, and the 

 teres minor, were completely torn oft" from 

 the humerus, carrying with them, however, a 

 scale of bone, which was ascertained to be the 

 surface of the greater tubercle into which 

 they are inserted." 



In order to ascertain the nature of the ob- 

 stacles which oppose the reduction of the 

 dislocated humerus, the scapula was fixed, 

 and the arm being raised to nearly a right 

 angle with the body, extension was slowly ap- 

 plied to the arm by pulling at the wrist; it 

 then appeared that so long as the hand was 

 held supine, the head of the bone remained 

 immovable; the chief resistance appearing to 

 be caused by the closing of the biceps and 

 triceps behind the head of the bone. The 

 muscles of the back of the scapula being de- 

 tached from the greater tubercle, could of 

 course afford no resistance ; but, on turning 

 the hand into the prone position, and giving a 

 motion of rotation inwards to the whole limb, 

 the extension being still maintained, the head 

 of the bone glided easily into its socket. The 

 appearances observed in this case are nearly 

 identical with those which are described by 

 Mr. Henry Thompson, in the Medical Ob- 

 servations and Inquiries, while they differ 

 materially from those which were found by 

 Sir Astley Cooper ; establishing an important 

 fact, which, indeed, might have been inferred 

 a priori, that in apparently similar dislocations 

 of the humerus, there may be very different 

 kinds as well as degrees of lesion, and conse- 

 quently very different causes of resistance to 

 reduction. " In Mr. Thompson's case," Sir P. 

 Crampton adds, " as in mine, the head of the 

 bone was found lodged on the inside of the 

 neck of the scapula, between the subscapu- 

 laris and teres major muscles ; but during the 

 eighteen days which had elapsed since the 

 injury had been received, the cellular substance 

 of the axilla had formed a kind of capsular 

 ligament, which embraced the head of the 

 bone, and contained a small quantity of mucus 

 resembling synovia. In Mr. Thompson's 

 case, the capsuiar ligament was completely 

 torn from the whole circumference of the 

 humerus. In mine it was detached to the 

 extent of more than half the circumference. 

 In both cases, the attachments of the ten- 

 dons of the supra- and infra-spinatus muscles 

 were torn off" with the part of the bone they 

 were inserted into ; in both cases, some 

 fibres of the subscapularis muscle embraced 

 the neck of the bone." In Sir Astley 

 Cooper's cases, on the contrary, although the 

 tendon of the subscapularis was torn through, 

 the supra- and infra-spinatus muscles retained 

 the connection with the greater tubercle, and 

 " until tliis muscle was relaxed, by raising the 

 arm, the humerus could not. be reduced by any 

 efforts which he (Sir Astley) could make." In 

 cases of dislocation of the humerus into the 

 axilla, which have been left long unreduced, 



