The movement structure of the mandible and alignment of the neck

The motion patterns of mandibular points were recorded in vivo in closed free movements of the mandible in the sagittal-vertical plane. The points ran along closed loops, which were evaluated by their area and length. All points whose loops showed areas of the same size regarding the sense of circulation formed straight lines. When the absolute area of the loops was taken into account, a valley with two minima was found in the function "absolute area versus position of the point", the point which showed the deepest minimum tallied with the position of the neuromuscular mandibular rotation axis. The points with loop lengths of same size formed elliptical lines, the perimeter of which was minimal for a point below the condyle. Morphological relations: the row of teeth in the upper jaw was found to be located below the line of minimal path lengths on the straight lines with constant areas, and the cervical spine was found to be arranged along the valley of the minimal absolute areas where the path lengths have their maximum.