The maxillary sinuses are cavities in the skull located behind the cheekbones, directly above the upper teeth. They are larger than the other paranasal sinuses and are more prone to infection. The actual evolutionary purpose of sinuses is unknown to science, but there are several theories. Some researchers believe sinuses work as sound chambers to make the voice louder, while others think they exist to reduce the weight of the skull; they may also help to humidify the air a person breathes, or even work as crumple zones to protect the brain from trauma in the event of an injury. Sinuses help the immune system function by facilitating the flow of mucus, but it is debatable whether they actually evolved for that purpose.
All sinuses are lined with a mucus membrane and covered with tiny hairs called cilia. The mucus collects foreign debris that a person breathes in and the cilia move back and forth, thereby helping to keep mucus flowing in the proper direction. This action helps to keep the airways clean and protect the body from disease.
In the maxillary sinuses, there are small openings called ostium that allow the mucus produced within the sinus to drain into the nose. If the cilia stop functioning properly, or if the openings become too small due to tissue inflammation, mucus is trapped in the sinus, and begins to attract bacteria. The result typically is a sinus infection.
One of the main reasons the maxillary sinuses are especially prone to infection is their close proximity to the teeth. Most sinus infections are caused by either head colds or allergies that linger, thereby resulting in backed up mucus. The maxillary sinuses are vulnerable to this as well, but they can also be infected due to dental inflammation, or even bacterial contamination directly from the teeth. If the teeth are the source of infection, dealing with dental issues can be an important part of the treatment.
Symptoms of maxillary infection include a feeling of pressure in the face, sharp pains in the cheeks, toothache, nasal congestion, fever, and fatigue. For mild sinus infections, most people rely on over-the-counter pain medication and decongestants. If the symptoms are more severe, doctors may prescribe antibiotic medications to kill the bacteria. Depending on the severity of the case, other treatments may also be used, including nasal sprays, nasal irrigation, steam therapy, prescription decongestants, and steroids. In extreme cases, surgery may be performed to enlarge the sinus openings to make it easier for the mucus to pass.