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This CT scan of a deviated septum also reveals some of the paranasal sinuses.

This CT scan of a deviated septum also reveals some of the paranasal sinuses.

What Are the Sinuses?

A sinus is a cavity—a space—within flesh or a bone. For instance, in my post about ear infection, I mention the mastoid sinus, which is a little space in our skull behind each ear.

But when most of us talk about our sinuses, we mean our paranasal sinuses. There are four pairs of these that connect to each other through small openings. They’re lined by mucous membranes similar to the ones in our nostrils. And, just like in our nose, these linings produce mucus, which drains out through these openings. Also like in our nostrils, they can get inflamed and swollen.

What are sinuses good for?

Good question. Scientists can only speculate. Take your pick of any or all of these choices. Sinuses may:

  • Insulate or cushion our brain.
  • Aid in the resonation of our voices.
  • Help keep the air moist that goes into our lungs.
Side note

Children only start developing paranasal sinus cavities around six years old. The sinuses aren’t fully developed until the late teens.

Why Do Sinuses Get Infected?

Since the parasinuses (sinuses around your nose) connect to each other and your nostrils by small openings, they’re also connected to the outside air and all of its germs.

If you get some kind of upper respiratory infection it can inflame and swell the membranes that line the sinuses. This can stop up the small openings that connect the sinuses. Without an opening, a sinus can no longer drain. Pressure builds, and the stopped-up sinus becomes a warm, moist breeding ground for viruses or bacteria—the same sort of breeding ground I explained in my post on skin abscesses. (In fact, sometimes, they do form abscesses that have to be drained by a doctor.)

And it’s not only colds and flu that can stop these sinuses up. Allergies can do it, or irritants, such as smoke.


>> Next: Sinus infection remedies.

The Survival Doctor's Guides to Burns and Wounds, by @James Hubbard


Photo by iamdonte on Flickr.