The developmental precursors of the nose are the neural crest cells, which begin their caudad migration towards the midface around the fourth week of gestation (see Image 1). Two nasal placodes develop inferiorly in a symmetrical trend. Nasal pits divide the placodes into medial and lateral nasal processes. The medial processes become the septum, philtrum, and premaxilla of the nostril; whereas the lateral processes type the sides of the nose. Inferior to the nasal advanced, the stomodeum, or future mouth, forms.
