Opening of jaw is done by -

Ans. is 'b' i.e., Lat pterygoid o Opening of jaw is caused by depression of mandible, which is mainly caused by lateral pterygoid. MovementsMechanism of movementMuscles involvedDepressionGliding movement in meniscotemporal compartment and rotatory movement in menisco mandibular compartment* Lateral ptery goids mainlyQ* Suprahyoid muscles namely, geniohyoid, mylohyoid, and digastricProtrusionGliding movement inmeniscotemporalcompartment* Medial pterygoids* Lateral pterygoidsRetractionReversal of protrusion* Posterior fibers of temporalis* Geniohyoid and digastricChewing involves vertical and lateral movements of the jawsGliding movement in meniscotemporal compartment of one joint and rotatory movement in meniscomandi bular compartment of other joint simultaneously# Alternate action of medial and lateral pterygoids of each side