What are the regions of the nasal cavity?
Vestibule, olfactory region, respiratory region
What are the nasal conchae and how many are there?
Curved shelves of bone which project out the lateral walls
Three -inferior -middle -superior
What are the pathways that the nasal conchae create called and how many are there and there location?
Inferior meatus: between the inferior concha and the floor of the nasal cavity
Middle meatus: between the inferior and middle conchae
Superior meatus: between middle and superior conchae
Spheno-ethmoidal recess: lies superiorly and posteriorly to the superior concha
Function of the nasal conchae?
Increase the surface area of the nasal cavity
Make airflow turbulent so it stays longer in the nasal cavity so it can be humidified
Which paranasal sinuses open up into the middle meatus and what is the opening marked by?
Semilunar hiatus - a crescent shaped groove on the lateral walls of NC
What do the middle ethmoidal sinuses drain into and what is it?
A bulge in the lateral wall formed by the sinus
Where does the posterior ethmoidal sinus drain into?
Level of the superior meatus
Where does the sphenoid sinus drain into?
Where does the nasolacrimal duct drain into?
The inferior meatus
Where does the Eustachian tube open into?
Nasopharynx at the level of the inferior meatus
Which bone is the cribriform plate a part of and what is does it allow?
Forms a portion of the nasal cavity
Contains small perforations allowing fibres of the olfactory nerve to enter and exit
Where is the sphenopalatine foramen located and what does it allow?
At the level of the superior meatus
Allows communication between the nasal cavity and the pterygopalatine fossa
Sphenopalatine artery, nasopalatine nerve and superior nasal nerves pass through here
What is the incisive canal?
A pathway between the nasal cavity and the incisive fossa of the oral cavity.
Transmits the nasopalatine nerve and the greater palatine artery
Why is it useful that the nose has a very rich blood supply?
Effectively change humidity and temperature of inspired air
Where does the nose receive blood from?
Internal carotid branches
-anterior ethmoidal artery
-posterior ethmoidal artery
These are branches of the ophthalmic artery, descend into the nasal cavity through the cribriform plate
External carotid branches -sphenopalatine artery -greater palatine artery -superior labial artery -lateral nasal arteries
Where do the veins of the nose drain into?
Follow the arteries
Into the pterygoid plexus, facial vein or cavernous sinus
In some individuals, a few nasal veins can join into which sinus and be a pathway for infection to spread into the cranial cavity?
The saggital sinus - a dural venous sinus
How can infection of the auditory tube diminish hearing?
Get swelling of the mucous linings, blocking the tube
Which nerves are for special sensory innervation of the nose?
Olfactory nerves from the olfactory bulb, which lies on the superior surface of the cribriform plate, above the nasal cavity
Which nerves supply general sensory innervation to the nose?
Nasopalatine nerve (branch of maxillary) and nasociliary nerve (branch of ophthalmic) - septum and lateral walls
Trigeminal nerve - external skin
How can a fracture of the cribriform plate occur?
As a result of nose trauma
Either fractured directly by the trauma or fragments of the ethmoid bone
What can a fracture of the cribriform plate lead to?
The plate can penetrate the meningeal linings of the brain, causing leakage of cerebrospinal-spinal fluid Increases the risk of meningitis, encephalitis and brain abscesses because the brain is exposed to the outside environment
Olfactory bulb which lies on it can be irreversibly damaged leading to anosmia
Where does the nasal cavity extend from and to?
Vestibule to nasopharynx
Which bones make up the bony part of the nasal skeleton?
Maxillae frontal processes
Frontal bone (nasal part and nasal spine)
Name the cartilgaes that make up the cartilaginous part of the nose
2 lateral cartilages
What are the parts of the nasal septum?
Anterior portion - cartilaginous
Middle portion - perpendicular plate of ethmoid bone
Posterior portion - vomer
Which bones is the hard palate made up of?
Palatine and maxillary bones
Complication of a fracture to the nasal cavity?
Structure of the olfactory cells?
Axonal process of the cells pass through the cribriform plate and penetrate the meninges before entering the olfactory bulb
Where is the area where nosebleeds usually occur? Why?
Rich in capillaries where all the arteries supplying the septum anastamose
Which artery is the cause of posterior bleeds?
Causes of rhinitis?
- Respiratory syncytial virus
What can nasal polyps lead to?
Where are they normally found?
Snoring/obstructive sleep apnoea
Close to the ostiomeatal complex of the nasopharynx
What are the different types of sinusitis?
Acute: 7-30 days
Sub-acute: 4-12 weeks
Chronic: >90 days
Causes of sinusitis?
Viral with secondary infection
- Streptococcus pneumoniae
- Haemophillus influenzae
What complications can an ethmoidal sinus air cell infection cause?
May break through the medial wall of the orbit
Close proximitiy to the optic canal which transmits the optic nerve and ophthalmic artery causing visual disorders
Why can sinusitis be perceived as toothache?
Superior alveolar nerve branches of the maxillary nerve (V2) supply both the maxillary teeth and the mucous membrane of the maxillary sinuses