Organ of Sense of Smell
Dual function : sense of smell and respiration
Warms and moistens the inspired air
Cleans the air
Olfactory receptors are placed in it to perceive the odours borne by the air

The external nose
Largely cartilaginous
The external nose consists of the nasal bones ( the bridge of the nose)
Upper and lower nasal cartilages
Alar cartilage - forms the lateral boundary of the nostril  - elastic cartilage - moved by the compressor and dilator naris muscles
Covered by adherent skin containing numerous sebaceous glands
The skin extends into the vestibule within the nostrils - has stiff hairs

The floor of the nose is the hard palate
Soft palate acts as a flap valve; breathing is stopped during swallowing; the valve shuts off the nasopharynx from the oro pharynx
The nasal cavity- nasal septum - divides the nasal cavity into two halves
The nasal cavity opens posteriorly into the nasopharynx - choanae
The respiratory mucous membrane of the nasal cavity is very vascular and red in colour. (ciliated columnar epithelium)

Olfactory mucous membrane
The epithelium in non ciliated
Called the neuroepithelium
Olfactory fibres are formed from this epithelium and they pierce the cribriform plate and pass to the olfactory bulb
The cavity of the nose
Floor - roof of the mouth - hard palate
Lateral wall
orbit (the ethmoidal air cells intervening)
The maxillary antrum
Three nasal conchae (turbinate bones) project downwards
Beneath the free inferior border of each concha is a meatus, called superior, middle and inferior meatus respectively
Paransal sinuses and the lachrymal duct open into the nose.
Supplied by external nasal nerve

Paranasal sinuses

The ethmoid sinus opens into the superior meatus

The maxillary and frontal sinuses open into the middle meatus

The nasolacrymal duct opens into the inferior meatus

    Applied anatomy
The mucous membrane covering the inferior concha can swell and 'block the nose' instantaneously.
When there is collection of pus or mucus in the maxillary or frontal sinuses antral puncture at the middle meatus is done to let out the pus/mucus
Pituitary surgery - through nose - trans sphenoidal approach

Frontal sinus in the forehead
Ethmoid sinus between our eyes
Maxillary sinus in our cheek bones Sphenoid sinus at the back of the nose

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