Which of the muscles show least EMG activity, when mandible is in centric relation?: (A) Posterior fibres of temporalis, (B) Middle fibres of temporalis, (C) Medial pterygoid muscle, (D) Lateral pterygoid muscle
Answer is D. The anatomic attachments of posterior and middle parts of temporalis, masseter and medial pterygoid muscle are actively involved in holding mandible in its centric relation. Most relaxed muscle out of given options is lateral pterygoid muscle and hence it will show least EMG activity.