It is not known why we have sinuses. One theory is that they help humidify the air we breathe in, and another is that they enhance our voice.
Sinuses are a system of connected hollow cavities in the skull. They are lined with a soft, pink tissue called the mucosa. Except for a thin layer of mucus, the sinuses are empty.
- The maxillary sinuses are the largest, about 2.5 cm across, located between the nose and the cheekbones.
- The frontal sinuses are located in the low centre of the forehead.
- The ethmoid sinuses are located between the eyes.
- The sphenoid sinuses are located on the interior side of the bone of the nose.