Sex determination of the human skull based upon line drawing from roentgen cephalograms.

The shape of the human skulls was studied with the aid of a personal computer to establish sex differences in quantitative anatomical terms. On the roentgen cephalograms from 50 adult males and 50 adult females, the lateral profile was transcribed onto an acetate sheet, on which the contour from the nasal apex to the forehead was digitized on a tablet digitizer into a series of dots which were input into the computer system. After this chain of dots was simulated by a spline function, the places most typically reflecting sex difference were determined in the profile based on the radius of curvature computed at each dot. The eminence of glabella and the nasal root, shown to be the places of skull apparently most characteristic of sex, were approximated to circular arcs with the least squares method, the radii of which were expected to serve for sexing. In both places, Student's t-test revealed a significant difference between the male and female groups (p less than 0.01). It was thus demonstrated that in male the eminence of glabella and the nasal concavity develop much more markedly than in female, presenting as a clear skeletal difference between both sexes.