Anatomy of Clefts
A cleft – or a gap – in the upper lip and/or palate is one of the most common birth defects among humans. The cleft results from the failure of the fetal tissue and bone to fuse and close together during the tenth to twelfth week of pregnancy. Clefts can involve the lip, the roof of the mouth, and the soft tissue in the back of the mouth.
Cleft lips come in a broad range of severity and disfigurement. It can be as mild as a slight cut in the upper lip, to a severe cleft lip involving total separation of the lip all the way up into the nose. Cleft lips can involve a single cleft (which is known as a unilateral cleft), or a double cleft (bilateral cleft). A cleft invariably occurs on the upper lip.
Cleft Palates can range from a tiny little hole in back of the roof of the mouth, to a major cavity that runs all the way from the front to the back of the mouth.