Cleft palate occurs when the 2 sides of the palate (roof of the mouth) do not join together during embryonic development, leaving an opening in the roof of the mouth. This creates a gap in the roof of the mouth that runs along its midline from behind the teeth to the nasal cavity. Many people with cleft palate are partially deaf and may have another birth defect. The opening in the palate permits communication between the nasal passages and the mouth. Surgery is needed to close the palate. Cleft palate is a common physical birth defect, although not as common as a cleft lip.