The paranasal sinuses are air-filled spaces located within the bones of the skull, surrounding the nasal cavity. They are named for the bones in which they are found: the frontal, maxillary, ethmoid, and sphenoid sinuses. These sinuses help to lighten the weight of the skull, produce mucus to keep the nasal passages moist, and enhance the quality of the voice. Each sinus is lined with a mucous membrane that helps trap dust and pathogens, preventing them from entering the respiratory system. The sinuses also play a role in regulating air pressure and temperature as we breathe. Proper drainage of the sinuses is essential for maintaining respiratory health.