What is the primary function of the paranasal sinuses?

The primary function of the paranasal sinuses is to moisten the nasal cavity, lighten the skull, and enhance voice resonance. These air-filled cavities are located within the bones of the skull and serve several important roles.

Firstly, by producing mucus, the sinuses help to keep the nasal passages moist, which is crucial for trapping dust, allergens, and pathogens, thereby aiding the respiratory system's filtering function. This moisture also helps maintain the health of the respiratory epithelium.

Secondly, the paranasal sinuses contribute to reducing the overall weight of the skull. Because the skull is relatively heavy, having hollow spaces within certain bones decreases the density of the skull, making it easier for the head to support its own weight and increasing mobility.

Lastly, the sinuses play a significant role in phonation. The resonance of the voice is enhanced by the sound waves reverberating within these cavities, contributing to the quality and richness of sound when speaking or singing.

In contrast, the other choices do not accurately represent the main functions of the paranasal sinuses. Storing spinal fluid pertains to the central nervous system, protecting the eyes from dust is primarily managed by the eyelids and lashes, and facilitating digestion relates to the gastrointestinal system