Sinuses are a part of the respiratory system. They pockets of air that connect to your nasal cavities, They produce mucus which is responsible for keeping your nose moist and collect dirt particles, germs, allergens, etc They also help in lightening the weight of the head, increasing the resonance of speech, and heating and humidifying the air we inhale. There are 4 paranasal sinuses, named- maxillary, ethmoid, sphenoid, and frontal sinuses.