AN UNUSUAL ANOMALY OF THE INFERIOR PORTION OF THE SCAPULA

Abstract

Hrdlicka and Gray have recently presented detailed studies of human scapula, including a resume of previous literature. Hrdlicka wrote: scapula of man is one of 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 Hrdlicka: body of scapula presents three main shapes or types, namely, triangular or wedge-shaped, with vertebral border straight; concave (or biconcave), with vertebral border (or both vertebral and axillary) concave; and convex, with its vertebral border markedly convex. The general shape of malformed scapula in case presented in this report would seem to conform to second main type of Hrdlicka, with mild concavity of axillary border. Hrdlicka also mentioned . inferior angle may present a distinct border (fourth border) instead of a point; and vertebral edge may definitely bend at terminal point of spine, which gives a fifth border above spine. The scapula in our case also presented a mildly evident fifth border above spine of scapula. Hrdlicka illustrated five variants of inferior angle (fourth border) of scapula. A comparison shows scapula in our case corresponded somewhat in appearance to of fourth variant of Hrdlicka, except in scapula of our patient central notching was deeper, and correspondingly larger and longer processes were present on each side; and, in addition, tiny projections were seen, arising from these processes. Since changes in our case were more pronounced than those which Hrdlicka would consider as vatiants, we feel 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 Hrdlicka. However, it will be pertinent to point out that, from an analysis of 1,285 scapulae of males of various nationalities, Hrdlicka found 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 specimens. He further stated although, in general, the two scapulae of same subject closely resemble each other, yet there are numerous small and occasionally even marked differences in shape as well as size of bones on two sides. Hrdlicka also found some sexual and racial differences; he discovered that juvenile scapula is far from finished in its form, but it changes in many respects during growth, and perhaps even during earlier adult period. He believed additional borders of scapula are of rather late development, and much of ultimate form which body of bone achieves is of functional nature and due to muscular activity.