nose [AS, nosu] , the structure that protrudes from the anterior part of the face and serves as a passageway for air to and from the lungs. The nose filters the air, warming, moistening, and chemically examining it for impurities that might irritate the mucous lining of the respiratory tract. The nose also contains receptor cells for smell, and it aids the faculty of speech. It consists of an internal and an external part. The external part, which protrudes from the face, is considerably smaller than the internal part, which lies over the roof of the mouth. The hollow interior part is separated into a right and a left cavity by a septum. Each cavity is divided into the superior, middle, and inferior meati by the projection of nasal conchae. The external part of the nose is perforated by two nostrils (anterior nares), and the internal part by two posterior nares. The pairs of sinuses that drain into the nose are the frontal, maxillary, ethmoidal, and sphenoidal sinuses. Ciliated mucous membrane lines the nose, closely adhering to the periosteum. The mucous membrane is continuous with the skin through the nares and with the mucous membrane of the nasal part of the pharynx through the choanae. The mucous membrane contains the olfactory cells that form the olfactory nerve that enters the cranium.
