UNDERSTANDING SINUS ANATOMY
Imagine walking into a very tall and narrow cave. As you look to one side of the cave, you see a sheer, solid wall rising steeply from the floor. You then look to the other side of the cave. The opposite wall is very irregular in shape. Rock formations hang down from the wall.
You climb the wall and find very constricted, small spaces in between the rock formations and the wall they are attached to. You wedge yourself into these spaces and shine a flashlight. You see very small holes in the wall that the rock formations nearly cover. You manage to position yourself next to these little holes and you shine your flashlight into them. You find that these tiny holes lead to large unexplored caverns. Congratulations! You now have a good idea what the internal anatomy of your nose looks like.
The sheer wall on one side of the cave is the nasal septum. You can touch the front part of your septum inside your nostrils and move it around, because it is made of very bendable cartilage (so as not to fracture when you bump it on something). Further back in the nose, the septum is made of bone.
The septum is a solid wall that divides the right and left sides of the nose. It is supposed to be dead straight but in the vast majority of people, it is at least a little bit wavy. If the septum is excessively bent one way or the other, it will block or restrict the empty space on either side of the “cave” and prevent adequate airflow on that side of the nose. A “deviated” septum can be surgically corrected to restore normal airflow.
The “rock formations” on the wall opposite the septum are called turbinates. They exist to interrupt the smooth flow of air into the nose. They cause the air to become turbulent (that’s why they’re called turbinates). Their presence also increases the total surface area of the lining of the nose. Why is this anatomy so complicated?
Besides allowing you detect substances floating in the air around you (your sense of smell), your nose functions mainly as a “reverse air conditioner” and the turbinates are critical for this function.
In your home or car, you use a/c to both cool and dry the air. That feels great on your skin, but your lungs don’t like cool, dry air. They like warm, wet air.
The inside of the nose is lined with special tissue called mucosa which is just like the lining of your mouth. The mucosa is very moist and warm. As cool/dry air enters the nose, the turbinates make the air swirl, and the air contacts the mucosa. The mucosa then imparts both warmth and moisture to the air. The air is then much more to your lungs’ liking. The only time you should breathe through your mouth is when the volume of air your lungs require cannot be handled by your nose alone – mainly during heavy exercise.
The tiny holes underneath the rock formations on the wall opposite the septum (the turbinates) are called ostia. The ostia lead to the hidden caverns. The hidden caverns are the sinuses.
The sinuses are cavernous, empty spaces in the face that surround the inside of the nose. These caverns lie above, below, between, and behind the eyes. No one is sure why we have sinuses, but it is likely that they exist to lighten and strengthen the facial bones.
The sinuses are lined with the same mucosa tissue that lines the inside of the nose and mouth. The mucosa is a very thin layer of cells which constantly make mucus. This “carpet” of mucus is pushed by tiny hairs embedded in the mucosa lining toward the holes leading out of the sinus. The mucus then drains into the nose through these tiny holes (the ostia).
Each sinus has a single small passageway for drainage. These small passageways also serve as a way for air to flow freely between the sinus and the inside of the nose. A root cause of sinus problems occurs when these small passageways are too small, and effective surgical treatment is designed to increase the size of the passageway to a normal, healthy diameter.
Any time you see “itis” at the end of a word, it means inflammation. Sinusitis (sine-you-site-us) is inflammation of the sinus cavities. The sinuses can be inflamed for any number of reasons. Most commonly, allergies will inflame both the inside of the nose and the sinus cavities. Allergic symptoms are most often relatively mild and well controlled with appropriate medications.
Sometimes, bacteria can cause an infection which inflames of the sinuses. This can happen if the ostia or tiny passageways between the nose and sinuses are narrowed or blocked for any reason. Blockage of the ostia will prevent the mucus that the sinus lining constantly produces from draining into the nose — the sinus will continuously try to push the mucus up against what amounts to a “closed door.”
Mucus which is then built up within the sinus provides a food source for bacteria to grow. This creates an infection which can become chronic or may resolve and then recur over and over again.
Often, repeated or chronic sinus infections will cause new bone growth around the tiny holes between the sinuses and nasal cavity, resulting in permanent narrowing of the sinus drainage pathways. Progressive narrowing of these passageways encourages new or worsened infections, which can narrow the drainage pathways further — a vicious cycle of infection and inflammation.
When the sinuses are inflamed, symptoms typically can include any of the following:
- Nasal stuffiness – congestion — trouble breathing through the nose, requiring a person to breathe through the mouth
- Drainage through the front or back of the nose (postnasal drip)
- Headache and/or pain/pressure/discomfort in the nose or around the eyes
- Pain in the upper teeth
- Reduction in the ability to smell
- Ear Pressure/trouble equalizing the ears/fluid in the ears
- Pain or pressure around the eyes with barometric pressure changes, such as when flying or diving, or with weather changes
These symptoms, particularly involving chronic fatigue or trouble breathing through the nose, can be extremely debilitating and dramatically affect a person’s quality of life. A recent publication concluded that chronic sinusitis can result in a level of suffering comparable to severe heart disease or emphysema.
A validated measure of sinusitis symptoms is used commonly by sinus surgeons and is called a SNOT-22 questionnaire. This can be found in the forms section of this website. A score of more than 7-10 is considered suggestive of significant sinus/nasal disease.