Muscles of Mastication — MFDS Part 1 MCQ

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EasyAnatomy (Head & Neck)Muscles of MasticationMFDS Part 1

Which muscle, when contracting bilaterally, is chiefly responsible for protrusion of the mandible?

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Correct answer: D — Lateral pterygoid

The lateral pterygoid is the principal muscle producing mandibular protrusion: bilateral contraction draws the mandibular condyles forwards. Unilateral contraction contributes to excursion of the mandible towards the opposite side. The masseter and medial pterygoid are primarily elevators, although their fibre orientation allows them to assist protraction; this is why the stem asks which muscle is chiefly responsible. Temporalis elevates the mandible, while its posterior fibres retract it. Geniohyoid is a suprahyoid muscle involved principally in moving the hyoid during swallowing and can assist mandibular depression when the hyoid is fixed.

Reference: Rathee M, Jain P. Anatomy, Head and Neck, Lateral Pterygoid Muscle. Structure and Function. Updated 2024. https://pubmed.ncbi.nlm.nih.gov/31747206/