What are the sinuses?

Sinuses of the face are cavities or spaces within the bones that help humidify air and secrete mucus to help with air filtration. Additionally, they contribute to the strength of the skull and its ability to resist trauma and allow more resonance in the voice.

The sinuses are often referred to as the paranasal sinuses because of their location and connection to the back of the nose. The sinuses develop as air sacs within the bones of the skull and are named by their location:

Frontal sinus: located above the eyes within the frontal bone of the skull

Maxillary sinus: located beneath the eyes under the cheekbones within the maxilla bone of the face

Ethmoid sinus: located in the ethmoid bone separating the eyes from the nose

Sphenoid sinus: located in the sphenoid bone at the base of the skull


What is a sinus headache?

Should the ducts that connect the sinuses to the back of the nose become inflamed, the ability of the sinuses to drain is decreased, and pressure builds within the affected sinus. There may also be associated swelling and inflammation of the lining of the sinuses, possibly resulting in increased mucus and fluid secretion. This increase in fluid and pressure causes the pain of a sinus headache. The term sinusitis is used to describe inflammation of the sinus (sinus + itis = inflammation).

What causes a sinus headache?

While a sinus infection (sinusitis) can be due to a viral infection much like a cold that causes swelling in the nose and decreases drainage of the sinuses, an allergic reaction (such as hay fever) may also begin the process of inflammation. As with any inflammation, there is swelling that in this case decreases the ability of the sinuses to drain and increased inflammatory fluid production (just like the weeping observed with a skin injury). The combination of more fluid and less drainage leads to the pain and pressure of a sinus headache.

Nature does not like stagnant fluid, and after a period of time bacteria and viruses can travel from the nasal cavities into the fluid and cause an infection. Less commonly, fungal infections may cause a sinus infection, and even more rarely, tumors can invade the sinus.

The maxillary sinus sits underneath the eye within the cheekbone. The upper teeth attach to the lower portion of this bone, and dental infections can travel up the root of the tooth and infect the sinus directly.