Figure 1

Ultrasound image paired with a schematic diagram of ultrasound observation of the main masticatory muscles—masseter and temporalis muscles. Thickness measurement of (A) masseter muscle in the upright position, (B) temporal muscle in the upright position, (C) masseter muscle in the supine position, and (D) temporal muscle in the supine position. Muscle thickness was measured sequentially in both resting and clenching conditions of the face and teeth for each position.