This study uses ultrasound to evaluate the function of the masseter, temporalis, and lateral pterygoid muscles in 30 Class II Division 1 hypodivergent patients between 10-14 years old during protrusion, lateral excursion, and clenching. It finds that each patient has a dominant and non-dominant chewing side, with the dominant side showing greater stretch but the non-dominant side showing more contraction to maintain occlusion. It also notes a shift in the midline during forward mandibular posturing toward the dominant side.