Which muscle assists lateral pterygoid during protrusion?

• A. Medial pterygoid
• B. Lateral pterygoid
• C. Digastric
• D. Mylohyoid

Answer: (A)

Protruding the mandible is a coordinated action of jaw muscles, with the lateral pterygoid acting as the main forward mover. When both sides contract, the mandible translates anteriorly. The medial pterygoid can contribute to this forward glide by working together with the lateral pterygoid, providing additional forward pull on the ramus and helping stabilize and refine the protrusive movement, especially as the teeth come into or move apart in contact. The other muscles listed—digastric and mylohyoid—primarily depress the mandible to open the mouth rather than promote forward movement; they don’t drive protrusion. So the medial pterygoid best fits as the muscle that assists lateral pterygoid during protrusion.