Muscles of Mastication — MFDS Part 1 MCQ

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ModerateAnatomy (Head & Neck)Muscles of MasticationMFDS Part 1

Which listed muscle acts bilaterally to protrude the mandible and contributes to its depression during active mouth opening?

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Correct answer: B — Lateral pterygoid

The lateral pterygoid is the correct answer. Acting bilaterally, particularly through its inferior component, it draws the mandibular condyles forwards and produces protrusion while contributing to mandibular depression during mouth opening. The digastric is an important accessory depressor when the hyoid is stabilised, but it does not protrude the mandible; this distinction makes A uniquely correct. The medial pterygoid can assist protrusion but primarily elevates the mandible. Masseter is chiefly an elevator, with its superficial fibres also assisting protrusion. Temporalis elevates the mandible, and its posterior fibres retract it.

Reference: Rathee M, Jain P. Anatomy, Head and Neck, Lateral Pterygoid Muscle. StatPearls, 2026 edition. https://pubmed.ncbi.nlm.nih.gov/31747206/