Paranasal sinus

Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the sphenoidal sinuses are behind the eyes. The sinuses are named for the facial bones in which they are located.

Structure

The paranasal sinuses are lined with respiratory epithelium. They are a combination of many smaller cells, including pseudostratified columnar epithelial cells, goblet cells, basal cells, and small granular cells. The paranasal sinuses form developmentally through excavation of the surrounding bone by air-filled sacs (pneumatisation) from the nasal cavity. This process begins prenatally, and the sinuses continue to develop throughout childhood.

Function

The function of the sinuses is unclear. One theory is that they function in humidifying and warming of inhaled air because of the large surface area provided by the ciliated epithelium. Another is that they give resonance to the voice. Other proposed functions include aiding in buoyancy and decreasing the weight of the front of the skull.

Clinical significance

Inflammation of the paranasal sinuses is known as sinusitis. Sinusitis can be caused by infection, allergies, and chemical or particulate irritation of the sinuses. Most viral sinus infections resolve without treatment. However, severe, progressive or persistent symptoms might require antibiotics. In rare cases, sinus infections can spread to the eyes or brain.

See also

• Nasal cavity
• Sinusitis
• Maxillary sinus
• Frontal sinus
• Ethmoid sinus
• Sphenoid sinus

References

Paranasal sinus Resources
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