Sexing the human skull through the mastoid process.

OBJECTIVE The purpose of this study was to evaluate the significance for sex determination of the measurement of the area formed by the xerographic projection of 3 craniometric points related to the mastoid process: the porion, asterion, and mastoidale points. METHOD Sixty skulls, 30 male and 30 female, were analyzed. A xerographic copy of each side of the skull was obtained. On each xerographic copy, the craniometric points were marked to demarcate a triangle. The area (mm ) of the demarcated triangle for each side of the skull (right (D) and left (E) sides) was determined, and the total value of these measures (T) was calculated. RESULTS Concerning the right area of the male and female skulls, 60% of the values overlapped; for the left area, 51.67% overlapped, and for the total area, 36.67% overlapped. The analysis of the differences between the sexes in the areas studied was significant for the 3 areas. Regarding the total area, which is the preferred measurement because of the asymmetry between the sides of the skull, the value of the mean was 1505.32 mm for male skulls, which was greater than the maximum value obtained in the female skulls. The value of the mean for female skulls was 1221.24 mm , less than the minimum value obtained for the male skulls. CONCLUSIONS This study demonstrates a significant result in the 3 studied areas, (D), (E), and (T). The total area values show less overlapping of values between the sexes, and therefore can be used for sexing human skulls. For the population studied, values of the total area that were greater than or equal to 1447.40 mm belonged to male crania (95% confidence). Values for this area that were less than or equal to 1260.36 mm belonged to female crania (95% confidence).