Sinuses are air-filled sacs (empty spaces) on either side of the nasal cavity that filter and clean the air breathed through the nose and lighten the bones of the skull. There are four paired sinuses ...

Sinuses are air-filled sacs (empty spaces) on either side of the nasal cavity that filter and clean the air breathed through the nose and lighten the bones of the skull. There are four paired sinuses ...

The function of the paranasal sinuses is not clear, but theories include humidification and warming of inspired air, lightening of the skull, improvement of vocal resonance, absorption of shock to the ...