Sinuses are air-filled spaces located within the bones of the face and skull. The human body has 4 pairs of sinuses, which are named based on their location: beneath the eyes (maxillary), forehead (frontal), between the eyes (ethmoid), and deep in the skull behind the ethmoid sinuses (sphenoid).
The sinuses are lined with a thin layer of tissue called the mucous membrane, which produces mucus to help trap and remove particles like dust and allergens from the air we breathe. The sinuses also play a role in regulating the temperature and humidity of the air we inhale.
