The Nature of Clefts

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Published: June 20, 2007
Updated: June 20, 2007

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The word "cleft" refers to an opening or space. We know that all clefts are different. They can occur at one or more different places on the face, such as the lips, the palate, or the gum ridge (alveolus). In human development, the right and left sides of the face fuse near the midline. A cleft results when this fusion does not properly occur. Clefts can be of different sizes; some are more severe than others.

Cleft of the Lip

A cleft lip appears as a gap in the upper lip. This opening can occur on the left or right side, or on both sides. A cleft that occurs only on one side is called a unilateral cleft. In a bilateral cleft, openings are present on both sides of a central upper lip segment, called the prolabium.

Not all lip clefts appear the same. There may be a barely noticeable notching of the red part of the lip, a ridge down extending down the lip from the nasal base, a partial division of the lip, or a complete division of the lip up into the floor of the nose.

You will hear us discuss the appearance of the nose because the anatomic changes that occur in cleft lip also affect the appearance of the nose. The growth, development, and correction of the nose in children with cleft lip is a specific area of interest to the Duke team’s surgeons.

Clefts of the Palate

The palate separates the nasal cavity from the oral cavity: "The floor of the nose is the roof of the mouth." A cleft palate is an opening in the palate that allows communication between the oral and nasal cavity. The palate is important for swallowing and the development of speech.

Like the cleft of the lip, cleft palate results from an alteration in the sequence of events that lead to fusion of right and left sides in the midline. The extent of the cleft will again vary from person to person. The palate, or roof of the mouth, is composed of two sections. The front half, just behind the teeth, is a bony section called the hard palate. Behind this is the soft palate containing muscles used in swallowing, eating, and speech. A cleft can occur in the soft palate only or extend forward through part or all of the hard palate.

Both the hard and soft palate are covered by a mucous membrane. In certain cases, the mucous membrane may appear intact, but the bones and/or muscles beneath it may not be appropriately fused in the midline. Despite its almost normal surface appearance, the underlying changes still can create functional problems, particularly for speech. This type of cleft is known as a submucous cleft palate.

Cleft of the Alveolar Ridge

The alveolar ridge, in front of the hard palate, is the bony ridge just above the gums. Your baby's upper teeth will erupt through this bony ridge. As with the lip and palate, clefts here can also occur on the right, the left, or both sides. If the cleft affects the alveolar ridge, whether completely or as a minor notch, it can affect the teeth. Sometimes extra teeth are seen; sometimes teeth will be missing. Often, the alignment of the teeth is affected. This is the very important reason that your cleft team includes dental specialists. They can provide needed treatment or work with your own local dentists and orthodontists to find the best treatment plan for your child.


Cleft of the soft palate only.

Cleft of the soft and hard palate.

Complete unilateral cleft of the lip, alveolus, and palate.


Complete bilateral cleft of the lip, alveolus, and palate.

Duke Guide to Care of Children with Cleft Conditions