This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Temporomandibular Joint, Subject name: Anatomy
Opening of the jaw is done by the: 
Select and explain. 
A. Medial pterygoid, B. Lateral pterygoid, C. Masseter, D. Temporalis
B: Lateral pterygoid
Answer: B: Lateral pterygoid 
Explanation: Ans: b (Lateral pterygoid) Ref.: BDC, 4th ed, VoL III, p. 152Depressing the jaw, ie. opening wide of the mouth is brought about mainly by the lateral pterygoid. The muscles which assist are the digastric, geniohyoid and mylohyoid.Movements that occur at the temporo-mandibular joint and muscles responsible:MOVEMENTMUSCLESDepressionLateral pterygoidElevationMasseter, temporalis, Medial pterygoidProtrusionLateral and medial pterygoidsRetractionTemporalis (posterior fibres)Lateral movementsTo the left: Lt. Lateral PterygoidRt. Medial Pterygoid To the right: Rt. Lateral PterygoidLt. Medial Pterygoid