The depressor anguli oris muscle is one of the muscles of the mouth. It arises from the lateral surface of the mandible posterior to the oblique line. It inserts into the modiolus at the angle of the mouth.
Its action is to depress and laterally displace the angle of the mouth. This action may be assisted by posterior fibres of platysma.
Depressor anguli oris is innervated by the mandibular branch of the facial nerve (VII).