Electromyographic Response of the Inferior Head of the Human Lateral Pterygoid Muscle during Mastication

Abstract

I investigated the activity of the inferior head of the lateral pterygoid muscle during masticatory movement and during application of the occlusal force during occlusion. The muscle activity of the lateral pterygoid, masseter, anterior temporal and posterior temporal muscles was recorded in eight adult males using electromyography, while at the same time recording the movement of the mandibular incisor region with a mandibular kinesiograph. The relation of muscle activity and mandibular position over time were analysed in detail.
It was found that the activity of the lateral pterygoid muscle played an important role during mastication. It was related to inferior and lateral shifts of the mandible during opening and to lateral shift during the early closing phase. This muscle also appears to play an important role in horizontal masticatory force during the latter part of the occlusal phase.