While men may have a reputation as the more thick-headed of the sexes, women actually have the thicker skulls, a new imaging study finds.

Jesse Ruan of the Ford Motor Company and colleagues at Tianjin University of Science and Technology in China examined head-scan images of 3,000 patients at the Tianjin Fourth Central Hospital and found some interesting differences between men and women that could have impacts on research and design efforts to protect the head in vehicle collisions.

The average thickness of a male skull was 0.25 inches (6.5 millimeters), while the average thickness of a female skull was 0.28 inches (7.1 millimeters).

Women had smaller skulls than men on average though, with an average front to back measurement of 6.7 inches (171 millimeters) and width of 5.5 inches (140 millimeters). men's skulls averaged 6.9 inches (176 millimeters) by 5.7 inches (145 millimeters).

"Skull thickness differences between genders are confirmed in our study," Ruan said. "The next step will be to find out how these differences translate into head impact response of male and female, and then we can design the countermeasure for head protection."

While a thicker skull provides more protection in a head injury, skull shape is also a factor. It will take more research to determine which feature is more important, the researchers said.

Another finding of the study, detailed in the most recent issue of the International Journal of Vehicle Safety, was that skulls thin with age.