Abstract
The purpose of this study was to confirm the existence of a rhythm for head movement during tapping movements, its coordination with jaw movements, and its functional significance.
A system that simultaneously tracks head and jaw movements was used.
Four normal adult males were selected as subjects.
The jaw range of motion and tapping frequency were designated according to tapping movements performed by the subjects.
During the experiment, the subjects' heads were not restrained.
The results were as follows:
1. During tapping movements, the head moved vertically and rhythmically, during jaw movements.
2. In average, the vertical range of head motion was about 6.5% of the range of jaw movement, and changes in the head's movement were proportional to those of the jaw.
3. The head moved in the opposite direction of jaw tapping movement, that is, when the jaw was in the opening phase the head moved upward, and when the jaw was in the closing phase the head moved downward.
4. It is considered that, in order to maintain balance and to smoothen functional jaw movement, the head moves cooperatively with the jaw.
5. Since head motion is considered as a cooperative and accompanying movement to that of the jaw, it may be affected by the conditions of jaw movement.
