Protrusion of the mandible is produced by which muscle group?

• A. Lateral pterygoid assisted by medial pterygoid
• B. Lateral pterygoid alone
• C. Medial pterygoid alone
• D. Temporalis

Answer: (A)

Protrusion of the mandible happens when the jaw is moved forward within the temporomandibular joint. The main movers are the lateral pterygoid muscles, especially their inferior heads, which attach to the neck of the mandible and to the articular disc. When both lateral pterygoids contract, they pull the condyle and disc anteriorly, translating the mandible forward. The medial pterygoid assists by providing an added forward pull on the mandible, helping to push it further forward and stabilize the movement. The temporalis primarily elevates and can retract the mandible, so it does not drive protrusion. Hence, protrusion is produced by the lateral pterygoids with assistance from the medial pterygoid.