The
Anatomy of a Sinus: How the Sinuses Work
Sinuses are air pockets in the bones behind the face and
jaw. There are four such chambers. The first two exist at
or shortly after birth:
- Maxillary sinus - behind the cheeks
- Ethmoid sinus - between the eyes behind
the bridge of the nose
The other two develop later:
- Frontal sinus - Developed around the age
of seven, these are located in the area of the forehead, over
the brow.
- Sphenoid sinus - Developed during adolescence,
located behind the ethmoids and eyes, deep in the face.
The
sinuses, which make the mucus that is intended to clean
out trapped particles and bacteria, all lead to the nasal
passages. They are linked by a mucous membrane. When the
mucus is thin (under healthy circumstances), it is swept
out by miniscule hairs along the sinuses called “cilia”,
and draws bacteria and fungus out of the body through the
nose.
Why
do sinuses get infected?
When
the sinus passages become narrow, swollen and/or constricted,
the mucus collects, thickens, becomes very attractive to
bacteria and fungus lurking in the environment, the flow
doesn’t happen properly, and the problem mounts up.
Many
things can contribute to the narrowing of the sinuses:
- Consistent exposure to smoky, chemical and toxic environments,
or even short-term exposure depending on the circumstances.
A good example is working with harsh cleaning products
in a room with no circulating air.
- Stuffy noses from cold and flu
- Allergic reactions - see our Sinusitis vs. Rhinitis
page (Link)
- Over-use of or dependency on decongestant sinus sprays.
- Chronic medical conditions which require long-term medications.
- Long-term water sports involvement, especially in chlorinated
pools
- Anatomical irregularities, broken bones or crushed cartilage
in the nose, or previous rhinoplasty (nose reconstruction).
Some
of these in turn can result in polyps forming in the nasal
passages or sinuses. These are generally soft non-cancerous
growths, but nevertheless bothersome.
Bad
sinuses can also affect the ear tunnels, especially in children.
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