Embryonic development of the head and neck: part 2, the branchial region.

The embryology of the branchial (pharyngeal) region is reviewed in terms of the embryonic pharynx, branchial apparatus and derivatives, tongue, larynx, and trachea. Derivatives of the branchial pouches, grooves (clefts), and arches are analyzed in relation to each other and to the first arch syndrome. Other common head and neck defects attributable to abnormal development of the branchial region are also discussed, particularly those defects involving the incomplete degeneration or the abnormal migration of branchial tissues.