Sinusitis (cont.)

A sinus is a hollow, air-filled cavity. For the purposes of this article, a sinus will referred to those hollow cavities that are in the skull and connected to the nasal airway by a narrow hole in the bone (ostium). Normally all are open to the nasal airway through an ostium. Humans have four pair of these cavities each referred to as the:

1. frontal sinus (in forehead),
2. maxillary sinus (behind cheeks),
3. ethmoid sinus (between the eyes), and
4. sphenoid sinus (deep behind the ethmoids).

The four pair of sinuses are often described as a unit and termed the "paranasal sinuses." The cells of the inner lining of each sinus are mucus-secreting cells, epithelial cells and some cells that are part of the immune system (macrophages, lymphocytes, and eosinophils).

Functions of the sinuses include humidifying and warming inspired air, insulation of surrounding structures (eyes, nerves), increasing voice resonance, and as buffers against facial trauma. The sinuses decrease the weight of the skull.

A sinus infection occurs when a pathogenic microorganism (virus, bacterium, or a fungus) grows within a sinus and causes intermittent blockage of the sinus ostium. Drainage of mucus and pus often occur when the blockage is relieved. The drainage usually goes from the nasal passages to the throat or out the nostrils. Such infections also cause inflammation (an influx of immune cells and swelling of the sinus tissue) of one or more sinuses. This can to block the openings of the sinuses and leads to discomfort.

Inflammation of the air cavities within the passages of the nose (paranasal sinuses) is referred to as sinusitis. Sinusitis can be caused by infection, but can also be caused by allergy and irritation of the sinuses.

Sinusitis is one of the more common conditions that can afflict people throughout their lives. Sinusitis commonly occurs when environmental pollens irritate the nasal passages, such as with hay fever. Sinusitis can also result from irritants, such as chemicals or the use and/or abuse of over-the-counter (OTC) nasal sprays, and illegal substances that may be snorted through the nose. About 30 million adults have "sinusitis."

2011 was a year that sinus infections are getting much lay press as sinus infections have been reported in several sports figures in basketball and baseball. The sinus infections have been reported to alter the ability of the athletes to play at their peak performance. One young (18yr old) professional baseball player reportedly died from a bacterial sinus infection that spread to his brain. Also, about 15 trauma victims of the May 2011 tornado disaster in Joplin, Missouri developed fungal infections that are rarely seen (some of them in the sinuses).

Source: MedicineNet.com
http://www.medicinenet.com/sinusitis/article.htm