[Human frontal inclination of the skull as a trait of sexual dimorphism--terminology and quantification]

The skull presents a variety of morphological traits suitable for sex discrimination due to the degree of their development. The vertical frontal inclination has been established. as another marker of sex discrimination, as a steep forehead is considered as a female and a receding frontal inclination as a male attribute. In the literature, there are many different ways to define the morphognostic term "frontal inclination" and "forehead profile" respectively. As part of the project "Digital Forensic Osteology" definitions of the frontal inclination commonly found in the literature have been tested with regard to their applicability to virtual skulls based on post-mortem CT data. The actual angle measurements were carried out automatically using software developed by the authors of this article. For the investigations, profile images of skulls generated from volume-rendered CT data were used in which anthropometric measuring points had been set manually. With the help of discriminant analysis it was tested whether sex discrimination on virtual skulls based on defined variables can be carried out with sufficient sensitivity. The measurement accuracy of the defined variables on the volume-rendered images turned out to be good. No significant sex differences regarding the tested variables were found. Using all the four selected variables the sensitivity for female skulls was only about 66%, whereas for male skulls it was not much higher than the rate of coincidence (53%). The results of this pilot study suggest that apart from extending the sample size the inclusion of additional variables based on strict consideration of validity and reliability criteria should be critically tested.