What are the sinuses?
Sinuses are spaces in the skull that are lined with tissue (mucosa). Small passages (osteomeatal complexes) connect the sinuses with the inside of the nose. The sinuses are shown below:
What is sinusitis?
When allergies, a deviated septum, or common cold prevent the sinuses from draining normally, a sinus infection (sinusitis) can occur. Because the draining spaces inside the nose are millimeters or less in size, even a small amount of swelling can cause sinusitis. A head cold that lasts more than a few days may be undiagnosed sinusitis. Click here to read more about sinusitis.