抄録
The balance of cervical muscle groups is easily destroyed because the head and cervical vertebrae do not exist en bloc, and are bound by the craniospinal joint through soft tissues. Thus, it is very important to elucidate the activity patterns of muscle groups that connect the head and neck during occlusion and mastication, and the mechanics of the skull and cervical vertebrae induced by activities of these muscle groups. In this study, we investigated the mechanics of the head and neck region during occlusion and mastication using rabbits. A triaxial strain gauge was attached to the occipital squama and bilateral parietal bones under anesthesia. After sufficient masticatory movement was confirmed following arousal from anesthesia, the animals masticated pellets, carrots, and cabbages, and the strain of each bone was measured. As results, it was clarified that the activities of the muscle groups of the occipital bone and 1st cervical vertebra are for maintaining the head at a position easier for mastication, and those of the 2nd cervical vertebra are for dislocation of the head to the masticatory side for efficient mastication, which leads to dislocation and deformation of the bones composing the skull for masticatory efficiency. [J Physiol Sci. 2007;57 Suppl:S244]
