The glenoid cavity of the scapula, under the influence of this disease, is generally much en larged ; and by becoming wider above, it loses much of its ordinary ovoidal figure, approach ing in its outline more to a circular form. The surface of the cavity appears preternatu rally excavated, its brim being elevated into a sharp margin. The cartilage of incrustation, as well as the glenoid ligament, are generally removed altogether, some parts of the surface are porous, and some covered with porcelain like enamel. Near the margins of the glenoid cavity, %here the capsular ligament arises, we may often find osseous productions attached to the capsular ligament, adding depth to the receptacle for the enlarged head of the humerus. The glenoid cavity will of course be found to present niuch variety of form. Sometiines the head of the humerus occupies its upper portion, and habitually remains in contact with the under surface of the acro mion and coracoid process, thus leaving the lower part of the glenoid cavity unoccupied.
Sometimes part of the head of the hume rus remains within the glenoid cavity, while the remaining portion of it occupies the neigh bouring part of the subscapular fossa. Occa sionally the head of the humerus will be found to have descended on the axillary mar gin of the scapula*; while in other cases equally rare, which Nye shall hereafter have occasion to refer to, the head of this bone may, under the influence of this disease, pass backwards on the dorsum of the scapula: under all these circumstances, the glenoid cavity must undergo special changes of form adapted to each variety.
Those who carefully study the anatomical characters of chronic rheumatic arthritis of the shoulder, cannot fail in the course of' their investigation to observe many deviations from the normal state of the joint, the result of this disease, which are well calculated to mislead those who are unacquainted with it ; to which we may here advantageously advert.
It has been repeatedly remarked, that one of the most constant anatomical observations we had to make in post-mortem examinations of the shoulder joints of those who had been is thinner than natural, and in a state of atrophy.* The coracoid process is not usually found so much altered by the existence of this peculiar disease in the shoulder joint as the acromion; but we have found its under concave surface in some cases to have entered into the forma tion of the shoulder joint, and to have pre-' sented a broad glenoid-shaped surface, which had been smoothed off from frequent contact with the head of the humerus, while the breadth of the process had been at the same time much increased.
We have thought it necessary to enter into this subject thus minutely', because we are convinced that, up to the present hour, these remarkable appearances, when met with, have been misunderstood even by some of the most intelligent anatomists and physicians. This circumstance may appear perhaps ca pable of explanation, by recollecting that the disease generally runs a long course, is not in itself fatal ; and hence, although the practical medical man may have had nutnerous oppor tunities of witnessing the symptoins of this disease in the living, he may never have had any opportunity in any case of informing himself of the true relation subsisting between the symptoms of this disease of the shoulder joint as observed in the living patient, and the phenomena which the post.mortem examina
tion of the same shoulder joint might have presented. On the other hand, when anato mists have heretofore discovered in dissection appearances which are stated to be truly those of chronic rheumatic arthritis of the shoulder, they have not at that time been able to learn the previous history of the case.
The following case may contribute some what to supply this deficiency :— Case. Chronic rheumatic arthritis of the shoulder. — J. Byrne, a servant, wt. 55, was admitted into the Whitworth Hospital House of Industry in 1834. Dr. Mayne, at that time resident clinical clerk in the hospital, informed the writer that, besides the disease of the lungs, for which the man was admitted, he also had an affection of the right shoulder joint, which presented all the characters at tributed to the case of partial luxation of the humerus, and was kind enough to invite the writer to examine him.
The man complained of an inability to use his right arm well, in consequence of his having for some years an affection of his right shoulder joint, in which he felt almost con tinually a dull boring pain. He could how ever perform, without much inconvenience, all those motions of the arm which did not require it to be raised near to the horizontal line. The joint felt to his own sensation somewhat stiff; and he was conscious, under certain movements of the arm, of a sense of something crepitating or crackling in the joint. -Upon viewing the shoulder in front, it had a wasted appearance; the acromion process was more prominent, rendering the bony eminences around very conspicuous ; the head of the humerus seemed to be a little higher than usual, and to have advanced somewhat forwards. The amount of advance was best seen by viewing the joint in profile or laterally. In this aspect a slight elevation and the increase of the antero-posterior measure ment of the joint became very obvious. When the arm was pressed by the surgeon, and very slight force used, the humerus could be easily made to descend somewhat, and at the same time to pass a little beneath the outer margin of the coracoid process ; and the finger could be readily pressed into the outer half of the glenoid cavity, into the space which the head of the humerus was found to have aban doned. When again the shaft of the humerus was elevated vertically, its superior extremity could be felt to strike against the under sur face of the acromion. In a word, the symp toms strongly resembled those usually as signed to the partial luxation forwards and inwards.