The sinuses are a system of hollow cavities in the skull. They are interconnected, and it is still uncertain why they exist. One theory is that they humidify the air that we breathe, another is that they reduce the overall weight of the skull. Another theory is that they enhance our voices.
The largest sinuses are about an inch across, the rest are much smaller.
- The maxillary sinus are in the cheekbones
- The frontal sinus are in the centre of the forehead
- The ethmoid sinus are between the eyes
- The sphenoid sinus are in the bones behind the nose
The sinus are lined with soft pink tissue called mucosa, and in a normal situation the sinus cavities are empty except for a thin layer of mucous.
The inside of the nose has ridges that humidify and filter air. A thin wall, called the septum, divides the nose. Most of the sinuses drain into the nose through a small channel or drainage pathway that is called the middle meatus.
Experts are not certain why we have sinuses, but some theories are that it was to help to humidify the air, to help to enhance our voices, or to help lighten the skull.
- Acute Sinusitis: Viruses, bacteria, or fungi infect the sinus cavity, causing inflammation. More mucous; nasal congestion; discomfort from the cheeks, forehead, or around the eyes; and headaches are common symptoms.
- Chronic Sinusitis (chronic rhinosinusitis): More than just a series of infections, chronic sinusitis is a persistent process of inflammation of the sinuses.
- Deviated septum: If the septum that divides the nose is too far to one side, airflow can be blocked
- Hay Fever (allergic rhinitis): Allergens like pollen, dust mites, and pet dander cause the defenses in the nose and sinuses to overreact. Mucus, nasal stuffiness, sneezing, and itching result.
- Nasal polyps: small growths in the nasal cavity. They can happen due to inflammation from asthma, chronic sinus infections, and nasal allergies (such as hay fever)
- Turbinate hypertophy: The ridges on the nasal septum are enlarged, which can block airflow.
Source: Web MD