AN UNUSUAL ANOMALY OF THE INFERIOR PORTION OF THE SCAPULA


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Abstract

Hrdlička and Gray have recently presented detailed studies of the human scapula, including a résumé of the previous literature. Hrdlička wrote: "The scapula of man is one of the most interesting bones of his skeleton. It presents numerous features and dimensions, . . . and many variations. Being essentially a functional product its anthropological value could hardly be expected to be very great, nevertheless its variants have more or less of phylogenic, ontogenic and racial significance."According to Hrdlička: "The body of the scapula presents three main shapes or types, namely, the triangular or wedge-shaped, with the vertebral border straight; the concave (or biconcave), with the vertebral border (or both vertebral and axillary) concave; and the convex, with its vertebral border markedly convex". The general shape of the malformed scapula in the case presented in this report would seem to conform to the second main type of Hrdlička, with mild concavity of the axillary border. Hrdlička also mentioned that ". . . the inferior angle may present a distinct border (fourth border) instead of a point; and the vertebral edge may definitely bend at the terminal point of the spine, which gives a fifth border above the spine". The scapula in our case also presented a mildly evident fifth border above the spine of the scapula.Hrdlička illustrated five variants of the inferior angle (fourth border) of the scapula. A comparison shows that the scapula in our case corresponded somewhat in appearance to that of the fourth variant of Hrdlička, except that in the scapula of our patient the central notching was much deeper, and correspondingly larger and longer processes were present on each side; and, in addition, tiny projections were seen, arising from these processes. Since the changes in our case were much more pronounced than those which Hrdlička would consider as vatiants, we feel that the scapula described here could reasonably be considered as showing a developmental anomaly rather than just a developmental variation.Many statistical figures of intetest, too numerous to be discussed here, are supplied by Hrdlička. However, it will be pertinent to point out that, from an analysis of 1,285 scapulae of males of various nationalities, Hrdlička found that a fourth border was present in 37.5 pet cent. of all specimens, a fifth border in 10.4 per cent., and a combination of fourth and fifth borders in 24.0 per cent.; neither border was present in 28.1 per cent. of the specimens. He further stated that although, in general, "the two scapulae of the same subject closely resemble each other, yet there are numerous small and occasionally even marked differences in the shape as well as the size of the bones on the two sides". Hrdlička also found some sexual and racial differences; he discovered "that the juvenile scapula is far from finished in its form, but that it changes in many respects during the growth, and perhaps even during the earlier adult period". He believed that the additional borders of the scapula are of rather late development, and that "much of the ultimate form which the body of the bone achieves is of functional nature and due to muscular activity".

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