Nasal Anatomy and Function

Abstract

At the fourth week of gestational growth, the cells of the neural crest (where the nose will be formed) begin to migrate caudally towards the midface. Two symmetrical nasal placoderms (rudiments of the olfactory epithelium) develop; afterwards, they will be divided by the nasal pits into medial and lateral processes (rudiments of the superior lip and nose). The medial processes will form the septum, filter and nasal premaxilla; the lateral ones, instead, will form the lateral nose structure; finally, the stomodeum (the anterior ectodermal portion of the intestinal tract) will develop to form the mouth below the nasal structure. A nasobuccal membrane separates the mouth (lower oral cavity) from the nose (upper nasal cavity). When the olfactory pits deepen, the choanae develop, putting in communication the nasal cavity with the nasopharinx (Fig. 3.1).