The supratrochlear foramen of the humerus in a South African dry bone sample.

The supratrochlear foramen (STF) of the humerus is the aperture that forms when the septum separating the coronoid and olecranon fossa is perforated. There are no known studies in the literature on the STF among various South African ethnic groups. The presence and shapes of the STF were established by visual observation from a sample of 538 skeletonized individuals with paired humeri (1,076) and of equal numbers between the sexes. Measurements of the transverse (TD) and vertical (VD) distance of the STF were obtained using extended jaw calipers. An osteometric board was used to measure the epicondylar breadth (EB). Sliding calipers were used to measure the distance of the medial epicondyle to medial aspect of the STF (MB) and that of the lateral epicondyle to lateral border of the STF (LB). The prevalence of STF in the South African population was 32.5% and predominantly on the left with the highest incidence among the Sotho population (41%) and the lowest incidence in Whites (16%). Females (19.5%) had a higher frequency of the STF compared with males (13%). The STF occurred in oval (136), round (77), triangular (9), and irregular (34) shapes. The average EB in this study was 56.1 mm, whereas the average MB and LB were 25.4 mm and 26.3 mm, respectively. The average TD was 6.3 mm and average VD was 4.3 mm. These findings may be of clinical significance to surgeons and osteologists and may have anthropological or forensic importance.