26. Skeleton of the nasal cavity. Walls, communications and elements passing through them.

BONY NASAL CAVITY

• The smaller anterior regions of the cavities are enclosed by the external nose, where is the large posterior regions are more central within the skull.

Lateral wall:

• Vestibule: most anterior.
• Atrium: posterior to the vestibule.
• The three nasal conchae (turbinates): they are three shelf-like projections (superior, middle, and inferior). Superior and middle conchae are parts of the ethmoid bone, while the inferior concha is a separate bone, and it is the largest one.
• A groove is present under each concha which is called meatus (so there are 3 meatuses receiving the openings of the paranasal sinuses.

Structure:

• It divided by the nasal septum into right and left halves.
• Both halves open anteriorly on the face through anterior nasal apertures, and posteriorly into the nasopharynx through posterior nasal apertures.
• Each half is rectangular in shape, having roof, floor, medial (septal) wall, and lateral wall.

• Each half contains 3 regions:
• Nasal vestibule: dilated part just internal to the naris. It is lined by skin and contains hair follicles.

• Respiratory region: largest part. It is lined by respiratory epithelium and rich in neurovascular supply.
• Olfactory region: occupies the apex of the nasal cavity and lined by olfactory epithelium.
• The lateral wall of each half receives the drainage of the paranasal sinuses