How can mouth breathing cause changes to the structure of the mouth & face?

Keeping an open mouth posture can cause dry and chapped lips, diminished strength of the muscles of the lips, cheeks, jaw and tongue; a lowered and anterior oral rest posture of the tongue which leads to an elongated, narrow face and retruded mandible; changes in the position of teeth/malocclusion (improper fit of the teeth), and a narrow, high palate.