Which of the following is a function of the ethmoid sinuses?

The ethmoid sinuses play a significant role in the respiratory system, primarily by filtering and humidifying the air we breathe. Located between the nasal cavity and the orbits of the eyes, these sinuses are lined with mucous membranes that produce mucus. This mucus traps dust, pollutants, and pathogens, preventing them from entering the lungs. Additionally, as air passes through the ethmoid sinuses, it becomes humidified, which is essential for maintaining the moisture levels in the respiratory tract and ensuring optimal functioning of the delicate tissues involved in gas exchange.

This function supports overall respiratory health and contributes to olfactory perception, improving the sense of smell. In contrast, the other options refer to functions not associated with the ethmoid sinuses. Cerebrospinal fluid production is related to the brain's ventricles, balance is primarily managed by the vestibular system in the inner ear, and while the sinuses can provide some structural support, their main function is not protecting the brain directly. Therefore, the primary and most accurate description of the function of the ethmoid sinuses is their role in filtering and humidifying the air.