A computer model of jaw and hyoid movement in the cat.

A digital model was used to study the varying movements of the feline jaw and hyoid in the sagittal plane. The effect of mandibular movement on the path of movement of the hyoid relative to the palate was investigated for model paths of movement of the hyoid, i.e. paths of movement that were always elliptical relative to the mandible. Major effects upon the path of movement of the hyoid relative to the palate were produced by two factors: (1) the presence of a fast open/fast close complex within the profile of jaw movement; (2) the time relationship of the backwards movement of the hyoid relative to that of the fast open/fast close complex. The average antero-posterior position of the hyoid in the mandibular plane and the angle of the major axis of the ellipse to that plane were less important factors. Within limits (relative to the mandible), the overall amplitude of the hyoid movement, its vertical position and the direction in which the ellipse was travelled were all unimportant factors in determining the general nature of hyoid movement relative to the palate.