Measurements on the grade of the human skull base and angle determinations]

1. The angle between the Os sphenoidale and the Clivus has been determined on 106 skulls. The mean was 117.68 degrees. 2. The altitude of the Foramen magnum with respect to the Frankfort plane was determined at -1.96 cm on the average. 3. The angle of inclination of the Foramen magnum to the Frankfort plane was determined from the altitude of the Basion and Opisthion and from the length of the Foramen magnum. The mean was -13.71 degrees. 4. In the inner base of the skull the altitudes of following structures have been determined: Planum sphenoidale (mean 2.34 cm), ground of the Fossa hypophysialis (1.32 cm), ground of the middle cranial fossa (-0.03 cm), ground of the posterior cranial fossa (-2.30 cm), upper edge of the Os petrosum (1.12 cm), Tuberculum jugulare (-0.21 cm), ground of the Meatus acusticus internus (0.45 cm). 5. In order to provide numerical data for the step-like building of the inner base of the skull, the differences between the altitudes of important structures from the inner base have been determined: Margo superior partis petrosae - Tuberculum jugulare (mean 1.35 cm). Opisthion - ground of the posterior cranial fossa (0.11 cm), Planum sphenoidale - ground of the middle cranial fossa (2.38 cm), ground of the middle cranial fossa - ground of the posterior cranial fossa (2.27 cm), Margo superior partis petrosae - ground of the posterior cranial fossa (3.35 cm), Margo superior partis petrosae - ground of the middle cranial fossa (1.15 cm).