ABSTRACT
This chapter discusses congenital midface anomalies, particularly relating to the nasal cavity, nasolacrimal apparatus, and craniofacial syndromes. Craniofacial development follows closure of the anterior neuropore approximately 25 days after conception. Neural crest cells are important in the understanding of the embryology of the face. An alternative theory to explain the pathogenesis of choanal atresia is the abnormal migration of neural crest cells to form the skull base/nasal cavities. Nasolacrimal duct stenosis is common in neonates and is caused by partial persistence of Hasner's membrane. Dacryocystoceles are rare masses manifesting at the medial canthus or in the nasal cavity. They may be unilateral or bilateral. Mesenchymal structures are formed from several elements that eventually fuse and begin to ossify to form the skull base and the nose. Before they fuse, there are recognized spaces between these elements, which are important in the development of congenital midline nasal masses.
