Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Nose and Sinuses

By

The Manual's Editorial Staff

Last full review/revision May 2022| Content last modified May 2022
CLICK HERE FOR THE PROFESSIONAL VERSION
Get the full details
Topic Resources

What is the nose?

The nose is one of your sensory organs and has 2 important jobs:

  • Breathing

  • Smelling

The top of the nose is made of bone. The bottom of the nose is made of cartilage. Cartilage is a smooth, tough tissue.

Inside your nose is an open space called the nasal cavity. It's lined with a membrane with many blood vessels. The cells of this membrane make mucus (a wet sticky substance). They also have tiny hairs (cilia) that help filter dirt from the air.

What are the sinuses?

Your sinuses are hollow spaces behind and around your nose. Because the sinuses are hollow, your skull isn't as heavy as it would be if it were solid bone.

Like your nasal cavity, your sinuses are lined with a membrane that makes mucus and has tiny hairs to trap dirt.

Each of your sinuses have small openings that connect into your nasal cavity. These openings allow air pressure to be the same in your sinuses as in the air outside so pressure doesn't build up and cause pain.

Locating the Sinuses

Locating the Sinuses

How does the nose work?

As the air passes through your nose:

  • The nose warms and moistens the air

  • The mucus and cilia filter out dirt so it doesn't reach your lungs

  • Receptor cells at the top of your nasal cavity detect odors

The sense of smell is complicated. There are many possible smells, many more than tastes.

When you sniff in air, the air passes over the receptor cells at the top of your nasal cavity. The cells are each sensitive to different chemicals. When the cells sense a chemical, they send a nerve message to the brain along the olfactory nerves. Your brain interprets this message as a smell.

The flavor of food involves both smell and taste. When your nose is stuffy, less air may reach your smell receptor cells. This is why, when you have a cold, food may not taste as good as usual.

What can go wrong with the nose and sinuses?

NOTE: This is the Consumer Version. DOCTORS: CLICK HERE FOR THE PROFESSIONAL VERSION
CLICK HERE FOR THE PROFESSIONAL VERSION
quiz link

Test your knowledge

Take a Quiz!
iOS ANDROID
iOS ANDROID
iOS ANDROID
TOP