Nose, Nasal Cavity And Paranasal Sinuses Flashcards
What do the nose and nasal cavity do?
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 is the external nose made from?
Cartilage
Nasal bone - susceptible to fracture because is very prominent
What is the vestibule?
Space inside external nose.
Lined with skin containing sebaceous glands and hair.
This is where inspired air enters.
Hairs assist in filtering trapped air.
What are the boundaries of the nasal cavity?
Roof: Cribiform plate
2 x lateral walls: with bony projections on
Floor: Hard palate (roof of the oral cavity)
Medial: Nasal septum
Why is the lateral wall irregular?
Because it contains 3 bony projections called conchae.
Superior conchae
Middle conchae
Inferior conchae
Why are the conchae in the lateral wall important?
They slow airflow by causing turbulence to allow for the air to be humidified. They also increase the surface area over which air passes and create 3 meatuses.
Why do you normally breath out of nose?
As nose allows you to modify the air so you don’t dry out the mucosa.
Other than conchae and meatuses, what else does the lateral wall contain?
Openings under the meatuses to allow for the drainage of paranasal air sinuses and the nasolacrimal duct into nasal cavity.
What does the nasal septum consist of and how does this structure allow for the formation of a septal haematoma?
Cartilage and bone
Cartilage of nasal septum receives blood supply from overlying perichondrium
Injury to nose can buckle septum and shear blood vessels.
Blood accumulates sub-perichondrium depriving underlying cartilage of it blood supply -septal haematoma.
What is a saddle nose deformity?
The consequence of an untreated septal haematoma.
It is avascular necrosis of cartilaginous septum causing saddling of nasal dorsum.
Can also develop infection in the collecting haematoma - septal abscess formation further increases the likelihood of avascular necrosis of septum.
What cranial never carries general sensation from the nasal cavity?
Trigeminal (Va and Vb) -ophthalmic and maxillary
Why is the nasal cavity highly vascular and lined with a mucous membrane?
Olfactory mucous membrane houses the olfactory receptor neurones to allow for smell.
The respiratory mucus membrane is made from pseudostratified columnar ciliated epithelium rich in goblet cells.
Mucus and cilia allow for air to be FILTERED, watery secretions allowed for air to be HUMIDIFIED and the rich blood supply allows for air to be WARMED.
What are nasal polyps?
Fleshy, benign swellings of nasal mucosa.
Usually bilateral and common in over 40yrs
Pale or yellow in appearance / fleshy and reddened
What are symptoms of nasal polyps?
Blocked nose and watery rhinorrhoea Post-nasal drip Decreased smell and reduced taste Snoring Unilateral polyp +/- blood tinged secretions may suggest tumour.
What is rhinitis?
A cold - an inflammation of the nasal mucosal lining
Commonly caused by acute infection or an allergic reaction
What are the symptoms of rhinitis?
Nasal congestion Rhinorrhoea (runny nose) Sneezing Nasal irritation Postnasal drip
What is the arterial supply to the nasal cavity?
Branches of ophthalmic artery (from internal carotid) and maxillary artery (from external carotid).
They anastomose in the anterior septum in Keisselbach’s plexus (little’s area)
where does Epistaxis most commonly come from?
Little’s area - plexus of blood vessles in vestibule.
What is the venous drainage of the nasal cavity?
Pterygopalatine venous plexus.
What are paranasal air sinuses?
Air filled spaces that are extensions of nasal cavity.
They are lined with respiratory mucosa and are named according to the bone in which they are found.
What do the paranasal sinuses do?
Help humidify and warm inspired air - reduce the weight of the skull.
They all drain into the nasal cavity via small channels called ostia. Most drain into the middle meatus.
What are the four paranasal air sinuses?
Frontal
Ethmoid
Sphenoid
Maxillary
What is acute sinusitis?
Symptomatic
inflammation of mucosal lining of nasal cavity and paranasal air sinuses often secondary to a viral infection of the nasal cavity.
It is self-limiting and so treatment is symptomatic.
What are the symptoms of acute sinusitis?
This is a clinical diagnosis based on history and examination,
Recent upper respiratory tract infection,
Blocked nose and rhinorrhoea +/- green/yellow discharge,
Pyrexia,
Headache / facial pain in area of affected sinus and worse on leaning forward.
What is the pathophysiology of acute sinusitis?
Primary infection leads to reduced ciliary function, oedema of nasal mucosa and sinus ostia and increased nasal secretions.
Drainage from sinus is impeded.
Stagnant secretions within the sinus become ideal breading ground for bacteria- secondary infection.
What makes it more likely to be an acute bacterial sinusitis?
Symptoms particularly severe at onset
Symptoms over 10 days without improvements (under 4 weeks)
Symptoms that worsen after initial improvement - secondary bacterial infection.
What are some common bacteria for acute bacterial sinusitis?
Steptococcus pneumonia,
Haemophilus influenza,
Moraxella catarrhalis
