Tongue, lips, and cheeks are in a state of balance and harmony with one another. This biomechanical equilibrium is reflected in the morphology of the dental arch in any case. It is imperative that the circumoral muscle band be taken into consideration as a significant component of the functional matrix that is accountable for the development of the dentoalveolar process. It appears that the form of the dental arches dictates the functional pattern of the tongue and lips to a much greater extent than the ideology that function alters form. As far as the musculature is concerned, it appears that resting pressures and the resting position of the tongue and lips are more essential than pressures during swallowing or speech in determining the shape of the dental arches.