14. Anatomy of the Nose, Nasal Cavity Paranasal Air Sinuses Flashcards
What are the functions of the nose and nasal cavity?
- Sense of smell
- Provides a route for inspired air
- Filters inspired air- trapping particles in nasal hair or mucous
- Moistens (humidifies) and warms inspired air
- Resonating chamber for speech
What doe the nasal cavity involve?
The nasal cavity extends from the nostrils anteriorly (anterior nasal apertures) to the posterior nasal apertures (also known as choanae) and has a roof, floor and two walls (medial and lateral). It opens into the most superior part of the pharynx, the nasopharynx.
what are the two apertures in the nasal cavity
anterior nasal aperture(nostril)
posterior nasal aperture(choanae)
What makes up the external nose?
Mostly cartilage, but also bone which forms the root of the nose (nasal bones and frontal processes of the maxillae)
What makes the nasal bone susceptible to fractures in facial injury?
the prominence of it
In nasal bone fracture, why is it hard to notice the fracture?
usually a lot of swelling
What is the vestibule of the nose ?
frontmost part of the nasal cavity, and is enclosed by cartilages.
What is the vestibule lined with?
skin containing sebaceous/ sweat glands and hair
What is the functions of the hairs in the vestibule?
Filters large molecules in inspired air
What forms the boundaries of the nasal cavity?
Lateral wall: maxilla
Medial wall: septum
Floor: hard palate
Roof: cribriform plate
What are the bony projections of the lateral walls called, how many and where do they come from?
Conchae/turbinates
- superior, middle (part of ethmoid bone)
- and inferior (bone in itself)
What are the spaces under the conchae called?
Meatuses
• Superior • Middle • Inferior
What is the functions of the turbinates/conchae?
- Slows airflow by causing turbulence of airflow
- Increases surface area over which air passes
Both of which means we can better humidify and warm the air
Which ducts drain into the nasal cavity and in which region do they drain?
Openings under the meatuses allow for drainage of
• Paranasal air sinuses into nasal cavity
• Nasolacrimal duct into nasal cavity
contents will then just be swallowed
which bones make up the roof of the nasal cavity?
nasal bone
frontal bone
ethmoid bone (cribriform plate)
sphenoid bone
What is the advantage of the close relationship with bones of roof of nasal cavity and floor of cranial fossa?
Can access structure in floor of cranial fossa through the nasal cavity for surgery - e.g accessing pituitary gland in surgery easier to go through nasal cavity
- Transsphenoidal surgical approach
What makes up the septum?
Perpendicular plate of ethmoid bone, vomer bone and cartilage
Where does the cartilage of nose receive blood supply from?
Cartilage is avascular, relies on overlying perichondrium for blood supply
What is a septal haematoma?
Blood between the septal cartilage and its perichondrium
What can cause septal haematoma?
- Injury to nose can buckle septum and shears blood vessels
* Blood accumulates sub-perichondrium…depriving underlying cartilage of its blood supply
What is the complication of septal haematoma and how does this occur?
Untreated septal haematoma leads to avascular
necrosis of cartilaginous septum and fibrosis, leading to a cosmetic distortion called saddle deformity - if
What can develop within the collecting blood in a septal haematoma?
Infection, causing a septal abscess further increasing likelihood of avascular necrosis of septum
How can a septal haematoma be identified?
look up into nose to look fro septal swelling
What carries general sensation from the nasal cavity?
Trigeminal nerve (branches of ophthalmic and maxillary), innervation extends to nasopharynx also