<P> There are two passages in the nasal cavity, not to be confused with nostrils. The entire nasal cavity is innervated by autonomic fibers . Sympathetic innervation to the blood vessels of the mucosa causes them to constrict, while the control of secretion by the mucous glands is carried on postganglionic parasympathetic nerve fibers originating from the facial nerve . </P> <P> The two nasal cavities condition the air to be received by the other areas of the respiratory tract . Owing to the large surface area provided by the nasal conchae (also known as turbinates), the air passing through the nasal cavity is warmed or cooled to within 1 degree of body temperature . In addition, the air is humidified, and dust and other particulate matter is removed by vibrissae, short, thick hairs, present in the vestibule . The entire mucosa of the nasal fossae is covered by a blanket of mucus, which lies superficial to the microscopic cilia and also filters inspired air . The cilia of the respiratory epithelium move the secreted mucus and particulate matter posteriorly towards the pharynx where it passes into the esophagus and is digested in the stomach . The nasal cavity also houses the sense of smell and contributes greatly to taste sensation through its posterior communication with the mouth via the choanae . </P> <P> Cilia and mucus along the inside wall of the nasal cavity traps and removes dust and pathogens from the air as it flows through the nasal cavity . The cilia move the mucus down the nasal cavity to the pharynx, where it can be swallowed . </P> <Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (February 2011) </Td> </Tr> </Table>

The function of mucus in the nasal cavities is to