Anatomy and physiology of the nose and paranasal sinuses

The primitive nasal cavity forms as the maxillary process of the first branchial arch and grows anteriorly and medially, fusing with the medial nasal folds and the frontonasal processes. The bucconasal membrane initially separates the primitive nasal cavity from the mouth, but it eventually breaks down, forming the primitive choanae. The palatal processes derived from the lateral maxillary mesoderm grow medially, fusing in the midline with each other and the septum to separate the nasal and oral cavities anteriorly. Posteriorly, this midline floor separates the nasopharynx and oral cavities and forms the soft palate.1