Figure 4.

Relative frequency distribution of foramen magnum (a) transverse diameter and (b) sagittal diameters between males and females. Histogram bin centers were spaced at every 2 mm. With regard to transverse length, most female crania had foramen magnums lengths between the bin centers of 30 and 32 mm (28.57% and 39.68%, respectively, for a total of 68.25% of the female sample). Male foramen magnum lengths also peaked at 32 mm (31.14%); however, a greater distribution of male foramina had longer transverse lengths (26.23% at 34 mm and 19.67 at 36 mm). Therefore, 77.04% of males had transverse lengths in the bin center range between 32 and 36 mm. With regard to sagittal length, the greatest portion of female foramina measured between bin centers 36 and 40 mm, each bin center accounting for 17.46% of the sample for a total of 52.38%. The greatest male relative distribution of sagittal lengths were in the bin centers of 38 (22.95%) and 40 mm (22.95%), accounting for 45.9% of male foramina