What causes Laryngeal cleft ?
What causes laryngeal cleft? During fetal development, the trachea and esophagus begin as one tube.  They later separate when a wall of tissue known as the tracheoesophageal septum forms, dividing the original tube into the trachea and esophagus.  If the tracheoesophageal septum fails to form, the trachea and esophagus may remain open to each other or abnormally shaped, causing abnormalities such as a laryngeal cleft, tracheoesophageal fistula, or esophageal atresia.  Exactly why these abnormalities occur is unknown.