[Facial morphology and the size and activity of the masseter muscle].

The study presented here was conducted for the purpose of investigating the possible relationship of masseter muscle size and activity to facial morphology. The study examined 50 adults, 25 males and 25 females, by means of electromyography, ultrasonography, and facial photography. The following results were obtained. There was considerable variation in masseter muscle activity and size both between the 2 groups and among individuals in each group. Partly there were strong differentiation's between the males and the females. The interrelationships between masseter muscle activity and size and facial morphology in both groups were generally weak, however, the links were more discernible in the women than in the men. Female subjects with thin faces and large mandibular planes had reduced masseter thickness, whereas women with a small anterior facial height index displayed when relaxed less masseter muscle activity and a smaller masseter width.