EXTERNAL, LATERAL AND NASAL CAVITY - ANATOMY 2021

 EXTERNAL NOSE AND NASAL CAVITY
EXTERNAL NOSE

It is a visible part of the face. 

SURFACE APPERANCE

The external nose is compromised of pyramidal shape.

The root is situated superiorly and it is continuous with the forehead.

 Apex - inferior. 

Lateral wall

The lateral wall of the nose is complicated by various bones and cartilages.

The bones forming the lateral wall are:

  • Nasal,
  • Frontal process of maxilla,
  • Lacrimal,
  • Conchae and labyrinth of ethmoid,
  • Inferior nasal concha,
  • Perpendicular plate of palatine, and
  • Medial pterygoid plate of sphenoid


The cartilages forming the lateral wall are:

  • Upper nasal cartilage
  • Lower nasal cartilage and
  • 3 to 4 minor alar cartilages

Blood supply of Lateral Wall


1. Anterosuperior quadrant - It is supplied by the anterior ethmoidal artery.

2. Anteroinferior quadrant - It is supplied by branches of facial and greater palatine arteries.

3. Posterosuperior quadrant - It is supplied by sphenopalatine artery.

4. Posteroinferior quadrant - It is supplied by branches of greater palatine artery,  that pierces the perpendicular plate of palatine


Nerve supply of Lateral Wall

1. Olfactory nerves - It supply the upper part, just under the cribriform plate of ethmoid up to the superior concha.

2. Anterior ethmoidal nerve - It supplies the Anterosuperior quadrant.

3. Anterior superior alveolar nerve: Which is a branch of infraorbital nerve - supplies the anteroinferior quadrant.

4. Posterior superior and lateral branches of pterygopalatine ganglion - It supplies the posterosuperior quadrant.

5. Nasal branches of greater palatine nerve supply posteroinferior quadrant.


NASAL CAVITY

The nose is a respiratory organ and it is known to be an olfactory organ too.

The nasal cavity has 4 functions: 

  • warms and humidifies the inspired air,
  • Sense of smell ,
  • Removes and traps the pathogen and other dust particle when inhaled,
  • It helps in draining and clearing the paranasal sinuses and lacrimal ducts.

DIVISIONS

Nasal cavity is the superior part of the respiratory tract. 

It extends from the vestibule to the nasopharynx and, 

It has 3 divisions.

  • vestibule
  • respiratory region
  • olfactory region

  • Vestibule:

This area is in the anterior part of nasal cavity.

  • Respiratory region:
It is lined by the ciliated pseudostratified epithelium and scattered with mucus producing goblet cells.

  • Olfactory region:
It is located at the apex of the nasal cavity.

it is lined by the olfactory cells and olfactory receptors

NASAL CONCHAE

Projecting out of lateral walls of the nasal cavity are curved selves of bone

These are called conchae or turbinates.

There are 3 conchae: inferior, middle and superior.

They project into nasal cavity. 

These cavity create 4 pathways: these pathways are called meatuses.

  • Interior meatus: It is situated between the inferior concha and floor of the nasal cavity.
  • Middle meatus: It is situated in between the inferior and middle concha.
  • Superior meatus: It is situated in between the middle and superior meatus.
  • Spheno-ethmoidal recess: It is superior and posterior to the superior concha.

The main function of the conchae: increase the surface area of the nasal cavity which helps in increase the inspiration of air.


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