Anatomy of the nose, nasal cavities and paranasal sinuses Flashcards
What structures make up the external nose?
Cartilage and Bone (nasal bone and maxilla)
What is the vestibule of the external nose lined with?
- Skin containing sebaceous / sweat glands
- Hair
What are the boundaries of the nasal cavity?
Roof: Cribiform palate
Floor: Hard Palate
Medial wall: nasal septum
What are the projections that come out of the lateral wall of the nasal cavity and what is their function?
Projections = bony conchae (Superior, Middle and Inferior)
Meatus= spaces between projections
Function: Slows airflow by causing turbulent airflow
Increases surface area over which air passes
What lines the lateral wall of the nasal cavity?
Respiratory epthelium
Why does your nose run when crying?
Tears from the lacrimal gland spill into the nasal cavity
Which meatus of the nasal cavity do the paranasal air sinuses open into?
Middle Meatus
What components make up the nasal septum?
A bony and cartilaginous part:
Bone: Vomer bone and Perpendicular plate (of ethmoid bone)
Cartilage: Septal cartilage
Where does the nasal cartilage recieve its blood supply from?
How can this be problematic in injury to the nose?
Nasal cartilage recieves blood supply from overlying perichondrium
Injury to nose can buckle the septum, shearing blood vessels →blood accumulates in subperichondrium →septal haematoma → underlying cartilage deprived of blood supply
How would you treat a septal haematoma?
By tamponade
Drain the haematoma and apply cotton wool forcing the perichondrium back onto cartilage
What is the consequence of an untreated sepatal haematoma and why does this happen?
Saddle Nose Deformity
Untreated haematoma causes avascular necrosis of septal cartilage
Haematoma is also a site for infection which further increases changes of avascular necrosis
Which cranial nerve carries general sesnation from the nasal cavity?
Trigeminal (Maxillary Vb branch)
The nasal cavity is lined with 2 mucus membranes, describe the 2 membranes and the function of each
- Olfactory mucus membrane - houses Olfactory receptor neurones for sense of smell (CN1)
-
Respiratory mucus membrane - pseudostratified columnar ciliate epithelium, rich in goblet cells
- filters air (mucus and cilia)
- Humidifies air (watery secretions)
- Warms air (rich blood supply)
What are nasal polyps and what do they look like?
Fleshy, benign swellings of nasal mucosa
Can be pale or yellow and are fleshy in appearance (can be reddened)
Are nasal polys usually bilateral or unilateral?
Bilateral
If unilateral and blood tinged this is more concerning - may suggest a tumour
Which arteries supply the nasal cavity?
What is the most common source for bleeding in epistaxis?
Branches of opthalmic and maxillary arteries
Anastamoses in the anterior septum form Kiesselbach’s plexus (or Little’s area)- the main site for nose bleeds
Bleeding from which artery in the nose is not easily treatable by first aid and may require surgery to ligate?
Bleeding from Spehnopalatine artery (a branch of maxillary)
At the posterior of the nasal cavity so cannot be reached by tamponade
Identify the paranasal air sinuses
Why is the maxillary sinus the most commonly affected paranasal air sinus?
It’s ostia is located high on the wall of the nasal cavity therefore drainage from the sinus is harder
Why is a rare, but serious consequence of ethmoidal sinus infection, sight threatening?
- Infection in air cells of ethmoid sinus can break through the thin, medial wall of the orbit
- Infection can spread to the orbit causing orbital cellulitis
- Infection sight threatening as it may involve the optic nerve or track back to involve intracranial structures
