Which muscle is a pure elevator of the jaw?

The medial pterygoid muscle, which originates on the medial side of the lateral pterygoid plate, and the masseter muscle, which originates from the zygomatic arch, pass medially and laterally to the ramus of the mandible to form a sling about the angle of the mandible. These muscles are powerful elevators of the jaw. The muscle bundles of the anterior portion of the temporalis muscle run nearly vertically into the coronoid process of the mandible, acting as a jaw elevator. The lateral pterygoid muscles run from the lateral side of the pterygoid plate and from the infratemporal fossa to the head of the mandible and the articular disk of the temporomandibular joint. Contraction of the lateral pterygoid muscles bilaterally protrudes the jaw. Unilateral contraction swings the jaw toward the opposite side. The submental muscles, assisted by gravity, are the primary depressors of the jaw. These include the geniohyoid and mylohyoid muscles as well as the anterior belly of the digastric muscle, all of which function in conjunction with the infrahyoid strap muscles.