Frontal sinuses are cavities of air that are located within the bones of a person’s forehead. These cavities may vary in size and shape from person to person. Interestingly, a person's frontal sinuses do not typically develop completely until he is at least 12 years old. In addition to the frontal sinuses, a person also has maxillary sinuses, which are positioned behind the cheeks, ethmoid sinuses, which are between a person’s eyes, and sphenoid sinuses, which are behind the ethmoid sinuses.
The frontal sinuses are open to a person's nasal airway via a hole or passageway that is referred to as an ostium. Together with a person’s other sinuses, the frontal sinuses make up a group or unit that is referred to as the paranasal sinuses. The sinuses are lined with cells that produce mucus as well as cells of the immune system. They are also lined with epithelial cells, which are cells that form the linings or surfaces of various parts of the body.
The frontal sinuses appear to have some important purposes, but scientists are not 100-percent certain of their primary purpose. They believe, however, that the sinuses help to decrease head weight since they are air-filled chambers. They also work to help warm the air that passes through a person’s nose and increase its humidity. The sinuses may also have an effect on the sound quality of a person’s voice. Additionally, sinuses help protect a person’s brain and eyes in the event of a blow in this area, acting as buffers.
Air flows through a person’s sinus cavities as he breathes normally. A person’s frontal sinuses drain through his ethmoid sinuses, which are located between his eyes, and into the nose itself. Sometimes, however, infection or irritation leads to the blockage of the opening through which the frontal sinuses drain, resulting in a sinus infection.
An individual may develop a sinus infection when a virus, bacterium, or fungus grows in the sinuses. This leads to swelling and inflammation of the sinus linings that can block the opening that drains the sinuses. The result is often pain or discomfort. For example, a person may develop a headache as well as stuffiness and a runny nose. While a person may develop a sinus infection because of a virus or other pathogen, similar irritation and symptoms can also develop as a complication of an allergy or other type of irritation.