The lower end of humerus has numerous fossae which play a significant role during extreme movements. Coronoid fossa and olecranon fossa are separated by a delicate supratrochlear septum; occasionally septum has perforation and form an aperture, named as Supratrochlear foramen (STF). The knowledge of this foramen will be beneficial for anatomists, anthropologists, orthopedic surgeons, and radiologists. The aim of the present study was to establish the prevalence and morphometry of STF of the humerus in South Indian population and to correlate with the previous studies. The present prospective study was carried out with 274 (146 left sided + 127 right sided) dried humeri of unknown sex and age. The distal humeri were examined for the presence of STF, morphometry such as diverse shapes, vertical and horizontal diameters, and distance from STF to medial, lateral epicondyle and also to the inferior margin of trochlea using digital vernier caliper. In the present study, out of 274 dried humeri, 69 showed presence of STF, 163 were translucent and 42 were opaque. The prevalence of STF was 25.18%. After keen observation, shapes of the STF were categorized accordingly. The oval (42%) showed higher percentage whereas the other shapes showed as follows: - irregular (12%), round (19%), rectangular (12%), reniform (9.7%), sieve (7.3%) and triangular (2%). The mean vertical and transverse diameters of STF on the right side were 3.12 ± 1.09 and 5.5 ± 1.83mm and on the left side, it was 3.47± 1.32 and 4.9± 1.5mm respectively. The mean distance from STF to medial and lateral epicondyle on the right side was 25.12± 3.1 and 28.09± 2.3mm and for the left side 24.97± 2.9mm and 27.16± 2.4mm respectively. The anatomical knowledge regarding the supratrochlear foramen is much promising for the orthopaedic surgeons during intramedullary nailing for supracondylar fracture of humerus. STF appears as a radiolucent area in radiographs, which may pose a difficulty for the radiologist in differentiating it from an osteolytic or cystic lesion. In addition, STF is predominantly found in the primates, it may act an evolutionary link between the humans and lower animals.
