The sinuses are a network of hollow cavities at the front of the skull, around the nose, cheekbones, and forehead. These cavities connect to the nasal airways and are part of the body’s respiratory system.
Human sinuses have a variety of functions, which are discussed later in this article. We also explore some common sinus problems and when you should speak to your doctor.
What Are the Sinuses?
Sinuses come in pairs, or paired groups, and are positioned symmetrically on the skull. The different types of sinuses are:
- Frontal Sinuses: Cavities in the forehead, just above each eye.
- Maxillary Sinuses: The two largest sinuses. They sit just behind the cheekbones.
- Sphenoid Sinuses: Located near the option nerve and the pituitary gland.
- Ethmoid Sinuses: A cluster of small air cells rather than a single air-filled cavity. Located in the bone between the brain and the nasal cavity.
The edges of the sinus cavities are lined with delicate tissue and a thin layer of mucus. The mucus is designed to catch bacteria, particles, and other foreign invaders that enter when we breathe.
Mucus in the sinuses drains into the nose via a narrow drainage tube called the middle meatus. From there, it is directed into the back of the throat by small hair cells called cilia. Mucus is swallowed with saliva, allowing potentially harmful bacteria to be destroyed by your stomach acid.