LXXIX Congenital Posterior Cleft Larynx (Laryngotracheo-esophageal cleft)

The larynx and trachea develop from a groove first seen in the foregut of the 4 mm embryo (28 days). Tracheo-esophageal separation begins caudally by a septum which extends rostrally to the larynx in the 9 mm embryo (33 days}.' The cricoid cartilage, formed much later, is a branchial derivative, which begins as a cartilaginous center on each side of the primitive glottis. During differentiation of the larynx, dorsal and ventral fusion occurs and development is complete in the 30 mm embryo (45 days}."