ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 



610 



shoulder joint was dissected by Mr. Macna- 

 mara, from whom I take the description of 

 the appearances, with the advantage of having 

 the preparation before me while I write. 



The dislocation was unattended with rup- 

 ture of any muscle, or the separation of any 

 tendon from its insertion into the bone ; by a 

 slight effort the dislocation was reproduced, 

 and the pectoral muscles being removed, the 

 polished head of the bone was now seen 

 lodged on the cervix of the scapula, at 

 the'root of the coracoid process, but extend- 

 ing nearly as far as the notch in the superior 

 margin of the scapula. The head of the bone 

 had passed out through a rent in the capsu- 

 lar ligament, over the upper edge of the tendon 

 of the subscapularis, detaching this muscle 

 from its connection, which is at this point 

 but slight, with the inner surface of the 

 scapula, and pushing its fibres downwards, 

 so that they formed a curve, which partly 

 embraced the neck of the humerus (fig. 

 437.). The supra- and infra-spinatus mus- 

 cles were on the stretch, but had suffered 

 no injury. The cellular substance cover- 

 ing their tendons was deeply ecchymosed, 

 so as to mark their course most distinctly. 

 On replacing the head of the bone, the open- 

 ing in the capsular ligament through which it 



Fig. 437. 



Dislocation forwards and inwards. ( Sir P. Cramp- 

 tons case.) 



had escaped from its socket, could be dis- 

 tinctly seen. It was formed, by a separation 

 of the ligament from the interior side of the 

 brim of the glenoid cavity from top to bottom, 

 it was bounded at the top by the tendon of 

 the supra-spinatus, and at the bottom by the 

 inferior edge of the tendon of the subscapu- 

 laris ; the rent was continued as far as the root 

 of the lesser tubercle of the os hunieri, and 

 was of sufficient extent, but no more, to per- 

 mit the head of the bone to pass easily through 

 it. The inferior part of the capsular liga- 

 ment, however, the part corresponding to the 

 axilla, was perfect. The great blood vessels 



and nerves lay to the sternal side of the head 

 of the humerus, and were forced a little out 

 of their course. The axis of the head of the 

 bone in its disturbed position was scarcely a 

 quarter of an inch higher than the axis of the 

 glenoid cavity. 



Sir P. Crampton observes, " the anatomy 

 of the recent case of dislocation forwards set- 

 tles the long disputed question as to whether 

 or not the humerus can be dislocated primi- 

 tively in any other direction than downwards, or 

 into the axilla ; it is plain, that in the case of 

 Wilson, the head of the bone was thrown at 

 once forwards, into the situation into which 

 it appears under the clavicle ; as the inferior 

 portion of the capsular ligament was not 

 ruptured, and the attachment of the sub- 

 scapularis and teres minor muscles to the in- 

 ferior costa of the scapula remained undis- 

 turbed." 



Mr. Key has given the following account of 

 the appearances observed in dissection of the 

 right shoulder joint of a patient who had had 

 for seven years an unreduced dislocation of the 

 head of the humerus, in the direction for- 

 wards and inwards. The specimen is pre- 

 served in the museum attached to St. Thomas's 

 Hospital. The head of the bone was thrown 

 on the neck and part of the venter of the 

 scapulas, near the edge of the glenoid cavity, 

 and immediately under the notch of the su- 

 perior costa : nothing intervened between the 

 head of the humerus and the scapula, the 

 subscapularis muscle being partly raised from 

 its attachment to the venter. The head was 

 situated on the inner side of the coracoid 

 process, and immediately under the edge of 

 the clavicle, without having the slightest con- 

 nection with the ribs; indeed, this must have 

 been prevented by the situation of the sub- 

 scapularis and serratus magntis muscles be- 

 tween the thorax and humerus. The tendons 

 of all the muscles attached to the tubercles of 

 the humerus were perfect, and are shown in 

 the specimen preserved. The tendon of the 

 biceps was not torn, and it adhered to the 

 capsular ligament. The glenoid cavity was 

 completely filled up by ligamentous structure, 

 still however preserving its general form and 

 character ; the tendons of the supra- and infra- 

 spinati and teres minor muscles adhered by 

 means of bands to the ligamentous structure 

 occupying the glenoid cavity, and, to prevent 

 the effects of friction between the tendons 

 and the glenoid cavity in the motions of the 

 arm, a sesamoid bone had been formed in 

 the substance of the tendons ; the newly 

 formed socket reached from the edge of the 

 glenoid cavity to about one-third across the 

 venter; a complete lip was formed around the 

 new cavity, and the surface was irregularly co- 

 vered with cartilage. The head of the bone 

 had undergone considerable change of form, 

 the cartilages being in many places absorbed, 

 and a complete new capsular ligament had been 

 formed." 



The accompanying wood-cut (fig- 438.) is 

 taken from a scapula preserved in the museum 

 of the College of Surgeons in Dublin, and re- 



