Structure and functions of our nose
The nose serves two purposes. It filters, warms and humidifies the air we breathe thus protecting the airways and lungs. Cold and dry air irritates the lungs.
It also enables us to appreciate smell. The latter can be life saving at times. Imagine cooking gas leaking from the pipe and a person trying to switch on the gas stove.
From outside the organ looks very simple. But it is a complicated structure inside. Several bones contribute to its boundaries.
The nasal cavity is divided into two nearly equal halves by the nasal septum. This division increases the surface area of the organ and improves the filtering efficiency.
The lining of the nasal cavity (mucous membrane) secretes a sticky substance called mucus which traps dust particles and microorganism.
The cells of the mucus membrane have fine projections called cilia which sweep away trapped dust and microorganisms by their movements. Multiple hairs crisscross the nasal cavity and contribute to its filtering function.
The bridge of the nose is formed by bones and cartilages. The two nasal bones meet in midline forming the body walls. The frontal processes of the maxillary bones also contribute to the bony framework.
This is the hard structure you feel if you press on the sides of the upper nose. Below that it is made of cartilages and fibrous tissue and is flexible.
The sidewalls of the nasal cavity are irregular due to bony projections. There are three projections on each side. They are called turbinates-superior (upper) middle and inferior (lower).
The projections are caused by the underlying bony structures called superior, middle and inferior nasal choncha. The superior and middle nasal loncha are parts of the ethmoid bone and the inferior nasal concha is a separate bone.
In between the turbinates are narrow spaces. The space below the superior turbinate is called superior meatus, that below the middle turbinate is called the middle meatus and the one below the inferior is called the inferior meatus.
The bones forming the nasal boundaries contain air filled spaces called sinuses (singular=sinus). The sinuses open into the nasal cavity on the side walls in between the turbinates.
Just above the superior concha is a narrow space into which the sphenoid sinus opens.
The posterior ethmoid cells open into the superior meatus.
The anterior and middle ethmodal cells open into the middle meatus. The frontal sinus and the maxillary sinus also open into the middle meatus.
The nasolacrimal duct carrying tears from the eye opens into the inferior meatus. That is why the nose becomes stuffy when a person cries.
The floor of the nasal cavity is formed in front by the palatine processes of the maxillary bones. Behind, the floor is completed by the palatine bones .
The roof of the nasal cavity is narrow. It is formed by the sphenoid bone , horizontal plate of the ethmoid bone which has perforations, frontal and nasal bones from behind forwards.
The fibers of the olfactory nerve which carry the sense of smell traverse through the perforations in the ethmoid bone to reach the brain where the impulses are interpreted by the brain.
This part of the brain is called the olfactory lobe. It is situated on the lower surface of the brain.
The nasal septum is formed by the vomer bone and the perpendicular plate of ethmoid. Some cartilages also contribute to the nasal septum. The septum is often deviated to one side of midline. Severe deviation of the septum may require surgical correction.
The lining of the superior nasal concha and the upper part of the nasal septum contain specialized cells called olfactory cells which can detect smell. Stimulation of these cells generates electrical impulses which are carried by the olfactory nerve to the brain.
Nose bleeds are common in children. This is commonly due to nose picking. Infection and inflammation of the nose can also cause nose bleeding. Occasionally nose bleeds occur during hot weather because the blood vessels dilate and rupture. Dry air can also irritate the nasal mucus membrane and cause bleeding.
Nose bleeds are usually not due to any serious disease. When there is nose bleeding the child should be asked to sit and slightly lean forward so that the blood can flow out. If the blood goes to the back of the throat and is swallowed it can cause nausea and even vomiting.
The vomited material may also cause some blood adding to the anxiety. Applying pressure over the soft part of the nose on the side of bleeding for a few minutes may be enough to stop bleeding. Keeping cold compress or ice on the bridge of the nose may also help.
Rarely nose bleeding can be due to some systemic disease like bleeding disorders.
Page last reviewed on 2nd January 2011
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