The Nasal Cavity

The nasal cavity connects the nares to the nasopharynx by way of the posterior nasal aperture (Cooper, 1994). In humans the nasal cavity is estimated to be 16 cm3 in volume (Harkema, 1992). The cavity is divided laterally by the nasal septum, which is comprised of cartilage more distally and bone more proximally. The cavity itself is enclosed by the lateral walls, a complicated structure containing portions of several bones; three of which form the foundation for the nasal turbinates (see Fig. 1.1). These turbinates (conchae) are rounded protrusions of these three bones and extend and furl throughout the nasal cavity. They function to direct air through the hollow space, promoting filtration, humidification, and temperature regulation (Dykewicz, 2003). The bottom most of these three protrusions is the inferior turbinate, which is the largest of the three and contains numerous venous spaces in its tissues. The other two turbinates, middle and superior (with the superior being smaller and located above the middle), are formed from portions of the ethmoid bone and actually form two of the four paranasal sinus cavities. Located between each of the turbinates lies an open air space called a meatus. Each is named for the analogous turbinate (inferior, middle, or superior), and contains openings from different sources of the nasal cavity. Though each meatus serves a specific role, their general function is receiving drainage from the sinus cavities and

Figure 1.1. Diagram of human nasal architecture.

providing passageway for blood vessels and nervous tissue. An example of this process is the nasolacrimal duct that opens to the inferior meatus. This duct functions to drain tears away from the orbits, resulting in congestion when an individual cries (Cooper, 1994; Citardi, 2003; Dykewicz, 2003).

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