Bilaterally, the medial pterygoid is one of the muscles of mastication. It originates from two sites:
- superficial head from the pyramidal process of the palatine bone and the tuberosity of the maxilla
- deep head from the medial surface of the lateral pterygoid plate and the fossa separating this and the medial plate
From these origins, muscle fibres pass inferiorly, laterally and posteriorly. They insert into the medial surface of the angle of the mandible posterior to the mylohyoid groove.
Innervation is from the nerve to medial pterygoid, a branch of the mandibular nerve (Vc).
Medial pterygoid has several actions:
- elevation of the mandible
- protraction of the mandible when medial and lateral pterygoid muscles contract bilaterally
- displacement of the mandible to the contralateral side when the just the ipsilateral medial and lateral pterygoid muscles contract
It has a key role in mastication.