To better understand sinusitis, it helps to understand the anatomy of the nasal passages and sinuses.
The sinuses are open cavities inside the bones of the face. Sinuses are located between the eyes, under the cheekbones, and in the forehead. They are connected by small channels that run between the sinuses. Normally, the sinuses do not contain fluid. There are four main sinus cavities.
The four main sinuses include:
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