抄録
To investigate the mechanical responses of the cranium and the cervical vertebrae during application of occlusal force to the teeth, occlusal force was applied to the teeth in a Japanese monkey fixed in a standing position under anesthesia, by electrically stimulating the central area of the bilateral masseter muscles. The following results were obtained:1. The sphenoid bone in the cranium was pressed by the zygomatic bone, which is anterior to the sphenoid bone, from the antero-superior direction, and was pressed by the temporal bone, which is posterior to the sphenoid bone, from the postero-inferior direction. Since the sphenoid bone is a single bone, and is anatomically located at the center of gravity of the cranium, the sphenoid bone was regarded as the mechanical center in the cranium.2. When the first molar on a unilateral side was forced to bite substances, the lamina of the vertebral arch of the second cervical vertebra on the non-working side was markedly extended in the supero-inferior direction. This suggested that the second cervical vertebral dens adjusts the cranial position to prevent the cranium from excess tilting to the working side. These results revealed that when occlusal force was applied to the teeth, the sphenoid bone controls the antero-posterior and bilateral movements of the cranium, and the second cervical vertebral dens controls the balance of the movement of the whole cranium. [J Physiol Sci. 2006;56 Suppl:S247]
