The sinuses are four hollow spaces filled with air in the skull that surround the eyes. Air passes in and out of these spaces, as well as mucus which drains through them and out of the nose. They also reduce the weight of the skull and give our voices a nicer sound.
The four sinus cavities are listed below:
- Maxillary - in the cheekbones
- Ethmoid - between the eye sockets
- Frontal - in the forehead and above the eyebrows
- Sphenoid - deep in the head at the back of the nose