Myofunctional appliances are sometimes referred to as the appliances that depend upon the orofacial musculature for their actions. In contrast to active removable appliances that make use of active components like springs, elastics and screws, the force components of myofunctional appliances are derived from the oro-facial musculature. The appliance either transmit, eliminate or guide the natural forces of the musculature.Functional appliances are used for growth modification procedures thatare aimed at intercepting and treating jaw discrepancies. They can bringabout certain changes such as an increase or decrease in jaw size, a changein spatial relationship of the jaws, change in direction of growth of the jaws, acceleration of desirable growth.