ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 



609 



the head of the bone is found altered in its the longitudinal axis of the limb passing from 

 form, the surface towards the scapula being below upwards, is much altered, being thrown 

 flattened, a complete capsular ligament en- 



Fig. 436. 

 Fig. 435. 



Axilla? y dislocation; case of long standing. 



virons the head of the os humeri. The glenoid 

 cavity is filled entirely by ligamentary matter, 

 in which are to be found small portions of 

 bone. These must be of new formation, as 

 no portion of the scapula or humerus is 

 broken. A new cavity is formed for the head 

 of the os humeri on the inferior costa of the 

 scapula, but this is shallow, like that from 

 which the os humeri had escaped. 



2. Dislocation forwards. This species of 

 dislocation is much more distinctly marked than 

 the former. The acromion is more pointed, 

 and the hollow below it, from the depression 

 of the deltoid, is more considerable. The 

 head of the os humeri can be felt through 

 the skin and pectoral muscle, and its con- 

 vexity seen, in thin persons, just below 

 the clavicle ; and when the arm is rotated, 

 the protuberance may be observed also to 

 rotate and accompany the motions of the 

 arm. The coracoid process of the scapula 

 is placed above and on the outside of the 

 head of the bone, which we know is covered 

 by the pectoris major muscle. The elbow is 

 thrown out more from the side, and further 

 back than it is in the case of dislocation into 

 the axilla (fig. 436.). 



Much difference of opinion seems to pre- 

 vail as to whether the arm is lengthened or 

 shortened, as the result of this dislocation of 

 the head of the humerus forwards. Mal- 

 gaigne and Dupuytren both assert that the 

 arm on the dislocated side is longer than na- 

 tural ; Sir A. Cooper expresses himself in 

 opposite terms ; he says, that in the disloca- 

 tion forwards and inwards of the head of 

 the humerus, the arm is shortened. In our 

 experience we have never found in the living 

 subject the arm shortened ; and in the speci- 

 men from which fig. 436. has been taken, the 

 centre of the new glenoid cavity is several 

 lines below the centre of the original cavity, 

 and the arm therefore must have been by, so 

 much, longer than natural. The direction of 



VOL. IV. 



v 



Dislocation of the head of the humerus forwards and 

 inwards. 



inwards towards the middle of the clavicle. 

 The pain attending this accident is less than 

 it is in the case where the head of the bone 

 is thrown into the axilla, because the nerves 

 of the axillary plexus are less compressed ; 

 but the motions of the joint are much more 

 materially affected. The strongest diagnostic 

 marks of the dislocation are these. The 

 elbow is separated from the side and thrown 

 backwards, and the head of the humerus can 

 be felt to move below the clavicle when the 

 arm is rotated. Sir Philip Crampton has 

 adduced the following example of the ordinary 

 dislocation forwards, in which the head of 

 the bone was thrown at once on the neck of 

 the scapula, without previously passing into 

 the axilla. 



" James Wilson, aet. 30, fell into a lime- 

 kiln, in the immediate neighbourhood of 

 the Meath Hospital, while the lime was still 

 burning ; he was drawn up by ropes, but just 

 as he reached the top of the shaft, the rope 

 broke, and he again fell to the bottom, a dis- 

 tance of about fifteen feet, on the ignited stones. 

 It appeared, on examination, made in the Mea' h 

 Hospital, that in addition to several extensive 

 burns and lacerations, there was a dislocation 

 of the humerus, under the pectoral mus- 

 cle. Mr. Macnamara, without assistance, re- 

 duced the dislocation, by merely drawing 

 the arm gently forwards and downwards 

 with one hand, while he pushed the head 

 of the bone towards the glenoid cavity with 

 the other. The man died in the course of 

 the day, from the conjoint effects of the burn 

 and the fall. Eighteen hours after death the 



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