WHAT ARE SINUSES?
Sinuses are air pockets that are located within the bones of the skull and face and are connected to your nasal passages by small tubes or channels, the osteomeatal complex. These channels permit air to flow from the nose into the sinuses and allow drainage of mucous from each sinus into the nose.
Sinuses actually begin to develop during the early years of life from an initial small pocket or pouch within the bones of the face. This pocket, which is connected to either the right or left nasal passage by the above channels, slowly enlarges and expands within the bone filling with air during this process. The air within our sinuses exchanges constantly with air flowing through the nose.
The growth of each sinus is variable, therefore, each of our sinuses are different in size and shape. This variation depends upon individual genes just as we all have different fingerprints. In fact, in each individual the right and left sinuses are generally different in size and shape.
The osteomeatal channel, or the connection from the sinus to the nose, can also vary substantially in its length or width. This difference can impact greatly on the ability of this channel to function properly. It may be very narrow or tortuous and therefore easily become blocked by swollen tissue such as occurs with sinusitis. Healthy sinuses have a constant exchange of air and simultaneous flow of mucous out. All of this occurs through the osteomeatal channels. Each sinus cavity has one connection to our nasal passage. We have 4 major sinuses on each side. Frontal, Ethmoid, Maxillary and Sphenoid. Blockage of these channels, partial or complete, by either structural conditions or swollen membranes is the cause of Sinusitis.
The nasal passages, the sinuses and their connecting channels are lined by tissue or membrane called respiratory mucosa. In the healthy state this tissue is very thin and light pink in color. Respiratory tissue produces mucous all the time. In fact many quarts of such fluid are produced in each of us every day. This mucous is moved by small hair like structures within the nose and sinuses, called cilia, to the back of the nose, down to the throat where it is then swallowed. We are not aware of this process because the mucous is thin and watery. In the condition called sinusitis the mucosa becomes very thick and even can form round or oval structures called polyps. This thickening can occur due to many factors which are discussed later. The mucous also can thicken and be difficult to clear from our nose and throat creating symptoms and feelings such as "post nasal drip," clearing of the throat and cough. Such are some of the symptoms of Sinusitis.