All About Sinuses: Anatomy, Function, Common Conditions, and Why They Become Congested

Your sinuses play an important role in keeping your body healthy and free of bacteria and invaders like dust, germs, and dirt by creating a thin layer of mucus that's constantly draining through your nasal passages. In this article, we will discuss what sinuses are, where the four types of sinuses are located, how they function, common sinus conditions, and ways to relieve congestion.

What Are Sinuses?

Your sinuses (also called paranasal sinuses) are hollow spaces or air-filled cavities in the skull and the bones around your nose. They are part of your nose and respiratory system, and they connect to your nasal passages. The air you breathe in moves through these passages, sometimes accompanied by unwanted invaders. The sinuses produce the helpful mucus that lubricates your nasal passages and the sinuses themselves.1,3

The Anatomy of the Paranasal Sinuses


There are four types of sinuses named for the bones that they're located in. Collectively, they're called paranasal sinuses.

Frontal Sinuses

You have two large frontal sinus cavities. Both your right and left frontal sinuses are in the center of your forehead (called the frontal bone) directly above each eye.

Maxillary Sinuses

The largest pair of sinuses located behind your cheekbones near the maxillae, commonly referred to as the upper jaw.

Sphenoid Sinuses

Located in the butterfly-shaped sphenoid bone, the two sphenoid sinuses are the deepest in the nasal cavity and can be found behind the eye near the optic nerve and the pituitary gland on the side of the skull.

Ethmoid Sinuses

Are made up of several discrete air cells within the ethmoid bone located between the nose and the eyes.

How Healthy Sinuses Function


The nose and sinuses are lined with a layer of mucous-producing cells. Here’s how they function:

  • They secrete mucus to protect against infection and humidify the air you breathe before it reaches the lungs. The thin mucus traps dirt, dust, and pollutants and drains out into the throat where stomach acid ultimately destroys it when it's swallowed.
  • Sinuses help to lighten the weight of the skull. Each sinus opening is inside the cranial bone which makes it partly hollow, so the head is lighter.
  • When you have nasal congestion or if your sinuses are obstructed, the reduced airflow can affect the quality of your voice resulting in hyponasal speech (or not enough nasal resonance).
  • They act as a crumple zone to safeguard the skull in case of an injury to the face. Think of sinuses like air pillows, which may be used to protect the face from trauma.

Common Sinus Problems and Symptoms


Sinuses can present a range of conditions requiring relief when the cavities around the nasal passages become inflamed or obstructed.


when fluid builds in in the sinuses, it allows germs to grow. Viruses cause most sinus infections, but bacteria also can cause some. Symptoms include a stuffy nose, pain or pressure in the face and teeth, fatigue, cough, sore throat, headache, and fever.

Sinus Headache

happens when your sinuses become inflamed due to an allergy or infection. It can cause deep pain in your cheekbones, forehead, and the bridge of your nose that usually worsens when you move your head.

Allergic Rhinitis

or Hay Fever is the body's reaction to allergens in the air that can cause a stuffy or runny nose.


can cause inflammation of sinus tissue which may create a breeding ground for sinus infections. Clogged sinuses can slow the usual flow of mucus which clears out bacteria and may make your sinuses more prone to infections.

Sinus Congestion Relief

There are a few ways to help relieve sinus pressure and nasal congestion—from home remedies to over-the-counter (OTC) medicines. Talk to your doctor if you have any questions or concerns.

Here are some Do-It-Yourself (DIY) ways to keep nasal passages moist:

  • Use a humidifier
  • Breathe in steam from a pot of warm water
  • Drink plenty of fluids
  • Use a nasal saline spray

Also, check out these tips from TYLENOL® on How To Clear a Stuffy Nose.

OTC medicines and decongestants can provide much-needed relief. We recommend TYLENOL® Sinus + Headache for powerful, nasal congestion, sinus pressure and pain relief. Please read and follow the product label. As always, talk to your doctor if the pain persists or if you are taking other medications.