]> 2026-07-31T10:04:31+00:00 WBR0937 0 en Masseter The masseter is one of the muscles of mastication, but it is responsible for closing the jaw. Lateral pterygoid The lateral pterygoid is the only muscle of mastication with two heads, and the only muscle responsible for opening the jaw. Medial pterygoid The medial pterygoid is responsible for closing the jaw. Temporalis The temporalis is a large muscle on the lateral edge of the skull responsible for closing the jaw. Mylohyoid The mylohyoid muscle is not classically considered a muscle of mastication. It serves to elevates the hyoid and the tongue during swallowing and speaking. Anatomy William J Gibson (Reviewed by Serge Korjian) An anatomy PhD student is performing an experiment to determine the muscles involved in mouth opening and clenching. He records electromyographic (EMG) activity from the inferior and superior heads of muscle A. Little EMG activity was noted in the inferior head during clenching of the mandible. However, strong activity was recorded from the inferior head during opening of the jaw. Which of the following does muscle A most likely represent? B Head and Neck Musculoskeletal/Rheumatology 2020-10-28T02:07:40Z 2459150.5886574 WBR0937