Morphometric analysis of foramen magnum in human skull for sex determination

Identification of human skeletal remains is the most important task for a forensic anthropologist during forensic examinations. The need for methods to estimate sex from cranial fragments becomes apparent when only a part of skull is brought for identification. In the present study, the morphometric measurements taken on foramen magnum in a documented Indian collection were analyzed for sex differences using standard osteometric techniques. Fifty adult skulls of known sex were included in the study. Morphometric analysis of foramen magnum was conducted using digital vernier calipers. Six standard parameters were measured and analyzed by discriminant function analysis using SPSS 16. Males displayed larger mean values than females for all measured variables but only one of the variables (maximum bicondylar breadth) exhibited statistically significant differences between the sexes. The results demonstrated a low level of sexual dimorphism in the cranial base of this sample. Based on sectioning point derived by the discriminant function, a value higher than the sectioning point was deemed to be male and value below it deemed to be female. The accuracy of sex prediction based on discriminant function analysis ranged from 66% to 70%. In stepwise analysis, maximum bicondylar breadth was found to be more discriminating variable providing an accuracy of 66%.