Movement 

Muscles 

Depression of Jaw

Lateral pterygoid assisted by digastric, geniohyoid and mylohyoid

Elevation of Jaw

Masseter, temporalis and medial pterygoid of both sides

Protrusion

Lateral and medial pterygoid

Retraction

Posterior fibres of temporalis and may be assisted by masseter, digastric and geniohyoid

Lateral or side to side movements

Medial and lateral pterygoid acting alternatively