Biomechanics and Biometry of the Anterior Skull Base

INTRODUCTION In the opinion of the famous anatomist Testut, the skull base is similar to a ship. This illustrative image obviously takes into consideration the existence of a bow designed to balance the undulatory movements caused by the C1 – C2 occipital articulations. It’s about the exoskull, which allows through its apophyses the insertion of various muscle groups which ensure the equilibrium of this unstable system at the first sight, should we consider the static equilibrium. The development symmetry of the skull base ensures the motion symmetry, the asymmetric development generating compensatory movements at the level of the calvarium but also in the C0 – C1 – C2 movement system (4, 7, 10). One can notice that the symmetry is given by the sagittal plane on the nasion – opistion direction, while the spheno – occipital articulation is similar to a torsion pushrod whose modification may generate various aspects of asymmetry: -torsion -lateral rotation -front-posterior rotation Similarly, a malposition of the temporal bone between the sphenoid and the occipital may generate forms of asymmetry through the difference of the semicircular channels.