Which muscle contributes most to unilateral mandibular translation during chewing?

• A. Masseter
• B. Medial pterygoid
• C. Temporalis
• D. Lateral pterygoid

Answer: (D)

When you chew on one side, the jaw moves laterally and the condyle translates forward on the working side. The lateral pterygoid is the primary muscle that drives this movement. Its fibers pull the condyle and the articular disc anteriorly, enabling the mandible to translate toward the opposite side as the jaw opens and shifts during chewing. Other muscles like the masseter and temporalis mainly elevate and stabilize the mandible, while the medial pterygoid assists with grinding but does not produce the same unilateral forward translation of the condyle. So, the lateral pterygoid best accounts for the unilateral translation observed during chewing.