The nasal cavity is divided into left and right halves by the nasal septum. Each nasal cavity has a roof and a lateral wall. The roof is formed by the cribriforrn plate of the ethmoid bone, through which olfactory nerves enter the nasal cavity. The lateral walls are formed from several different bones, but their most striking features' their three conchae or turbinates, are formed primarily from the ethmoid bone and a separate bone known as the inferior nasal concha. The conchae are large, medially-directed bony elements which are covered with highly vascular mucous membranes.
Air is thought to be heated and humidified as it is drawn past the conchae during breathing.
Beneath each shelf-like concha is a meatus. The meatuses serve as the openings of communications between the nasal cavity and the paranasal sinuses The paranasal sinuses are a series of membrane lined cavities within the bones of the face. Four pairs of sinuses are recognized and each is named by the bone in which it lies. The frontal sinuses lie in the frontal bones above the orbit and can be quite extensive. They communicate with the nasal cavity by an opening in the anterior end of the middle meatus.