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What Are the Sinuses?

The sinuses are mucus-lined, air-filled cavities within the bones of the face. They surround and connect to the nasal cavity.

The Four Types of Sinuses

The sinus system consists of four pairs of cavities in the skull, which mirror each other on the right and left sides of the face. The sinuses, named according to their locations, vary in size:

  • The frontal sinuses are located above the eyes, in the lower part of the forehead.
  • Maxillary sinuses, the largest, are located in the cheek bones.
  • Ethmoid sinuses are located between the eyes, near the inside corner of each eye.
  • Sphenoid sinuses are located in behind the ethmoid sinuses, in the bones behind the nasal cavity.

The Sinuses and How They Connect to the Nasal Cavity

The sinuses are connected to the nasal cavity by an opening called the ostium. The nose contains two nasal passages, which are separated by the nasal septum, a bone and cartilage wall. Along the of sides of each nasal passage, opposite the nasal septum, are three soft-tissued covered bones called nasal turbinates (inferior, middle and superior). Nasal turbinates are also referred to as nasal concha. Beneath each turbinate is an area called a meatus (inferior, middle and superior). Air flows through the crevice-like spaces between the turbinates and the septum.

The Role and Function of the Sinuses

The sinuses decrease the weight of the skull and also affect the quality of the voice.

Their main function, however, relates to immunological defense. The sinuses play a role in protecting the nose from pollutants, microbes, dust, and other foreign matter. Mucus, produced by the thin pink membrane that lines the sinuses, acts as a barrier to bacteria, disease germs, and particulates. Mucus is cleared out via tiny hair-like projections (cilia) that are embedded in the membrane.

As mucus is removed from the sinus cavities, it enters the nose via the ostium. The sinuses drain into an area beneath the middle meatus called the osteomeatal complex, the most important “hub” for the sinus openings. The mucus is moved to the back part of the nose (the nasopharynx), where it can be deposited into the throat and swallowed.

If the sinuses become infected due to allergies, bacteria, fungi or a virus, they can become inflamed. A sinus infection can cause nasal stuffiness, pressure, and serious discomfort in the forehead, around the eyes, and in the cheeks.

Your Sinus Evaluation with Dr. Alexis D. Furze, Orange County, CA

Dr. Alexis D. Furze is a California board-certified head & neck and facial plastic surgeon who specializes in treating sinus problems. If you are experiencing sinus irritation, contact Dr. Furze’s Newport Beach office today to make an appointment.


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Patients Say

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"Dr. Furze is a wonderful, thorough, intelligent, conservative, approachable, doctor with an excellent bedside manner. I had a sinus procedure done last year with Dr. Furze and he did an excellent job."

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