What are sinuses?

Sinuses are paired air cavities/spaces (pockets) found in the cranial (head) bones. Sinuses are also referred to as "paranasal sinuses". They are connected to the nose on the facial part of the skull where air passes and mucus drains.

We have four paired sinus cavities. Each sinus cavity has an opening (ostium), which opens into the nasal passages for free exchange of air and mucus. The mucus linings have ciliated epithelium (cells with fines hairs) that moves dirty mucus from the sinus cavities which drains into the nasal passages.

Sinuses are often confused with sinusitis. Sinusitis is a condition that occurs when your sinuses become inflamed and infected. Click here to learn more about sinusitis.

The four types of sinuses cavities

Sinus cavities vary according to location in the facial bones of the skull - they can become inflamed individually or collectively.
When these sinuses become infected it is known as sinusitis.

There are four pairs of sinus cavities:

• Ethmoid (between the eyes) sinuses. These sinuses are located behind the bridge of the nose and at the "root" of the nose between the eyes. We are all born with ethmoid sinuses and as we grow, they also grow. When these cavities become inflamed, you have a condition called ethmoiditis.
• Frontal (forehead) sinuses. These sinus cavities are located above the eyes in the region of the forehead and only develop around seven years of age. When the frontal cavities become inflamed, you have a condition called frontal sinusitis.
• Maxillary (cheekbones) sinuses. These sinus cavities are found on either side of the nostrils in the cheek bones. They are present at birth and grow as we grow. Inflammation of maxillary cavities due to bacterial, viral and other irritants is called antritis.
• Sphenoid (behind the eyes) sinuses. These sinus cavities lie deeper in the skull behind the ethmoid sinuses and the eyes. We only develop sphenoid sinus cavities during adolescence. Inflammation of these cavities due to any irritant is called sphenoiditis.

Why do we have sinus cavities?

• They lighten the weight of the skull and this is the reason why your head feels heavy and you feel tired and sleepy during a sinus attack.
• They give resonance to your voice.
• They also filter and moisten the air that we breathe.
• They also remove unwanted air particles.

Here are more topics on sinus and sinus problems that might be of interest:

• Causes and types of sinusitis.
• What is Rhinosinusitis?
• How can I prevent sinusitis?
• What remedy is for my condition?