The paranasal sinuses are air-filled extensions of the nasal cavity. They are located in the face/skull and connect directly or indirectly to the nasal cavity and nose through narrow drainage pathways. The frontal sinuses (purple) are located in the forehead region, the ethmoid sinuses (blue) are located between the nasal septum and the eye and just below the brain, and the maxillary sinuses (green) are located in the cheek region below the eyes. The sphenoid sinuses (red) are located behind the ethmoid sinuses and are closely related to important anatomical structures such as the optic nerves that are required for vision, the pituitary gland, and the carotid arteries that carry blood to the brain.
Although there is much debate about the actual purpose of the sinuses they do serve three main functions:
- Resonance of the spoken voice – helps make our pitch and timbre unique
- Protection of surrounding vital structures (crumple-zones)
- Lighten the weight of the skull
Mucus is produced in the nasal cavity and sinuses by the lining called mucosa. Along this mucosa are cells which have small hair-like projections called cilia that push the mucus out of the narrow sinus openings. Other cells help filter the inspired air and prime the immune system. Normally, nasal mucosa produces roughly a cup of mucus a day that is pushed into the back of the nose and eventually swallowed.
Sinusitis is a term that refers to inflammation of the paranasal sinuses, a major health problem in the United States that substantially affects up to 1 in 7 adults. The effects of sinusitis can be disabling in many respects, and have been shown to affect the quality of life, productivity, & finances. Symptoms of sinusitis may include nasal blockage/congestion, facial pain and pressure, nasal drainage, post-nasal drip, and decreased sense of smell and taste. In addition, some patients experience fatigue, headaches, low-grade fevers, tooth pain, eye pressure, and trouble concentrating.
The cause of sinusitis can be infectious or noninfectious. Regardless of the cause, inflammation leads to swelling of the nasal lining and the already narrow openings of the sinuses are made smaller– mucus production is increased and adequate drainage is limited. With long-term swelling and inflammation, the cells of the mucosa are also damaged and cilia can no longer work as effectively. This can lead to a prolonged chronic sinus infection and/or recurrent sinus infections.