8. paranasal sinuses (lecture) Flashcards
what are paranasal sinuses?
air filled spaces that are extensions of nasal cavity
what are paranasal sinuses lined with?
respiratory mucosa (also ciliated and secrete mucus) pseudostratified ciliated columnar epithelium with goblet cells
function of paranasal sinuses?
humidify and warm inspired air
reduce weight of skull
where do all paranasal sinuses drain into?
nasal cavity via small channels (ostia) - most into middle meatus
what can infections in the nasal cavity involve?
sinuses (sinusitis)
maxillary sinus most commonly affected
what are the 4 pairs of paranasal sinuses?
frontal
ethmoidal
sphenoidal
maxillary
how are paranasal sinuses named?
according to which bone they are found in
what do important anatomical relations of the paranasal sinuses include?
the orbit
anterior cranial fossa (ethmoidal air cells and frontal sinus)
roots of upper teeth can sometimes project in maxillary sinus
what is acute sinusitis?
acute inflammation of lining of sinus lasting (<4 weeks)
what are common causes of acute sinusitis?
commonly infective,
often secondary to viral infection of nasal cavity (common cold)
what is diagnosis of acute sinusitis based on?
history and examination:
- non-resolving cold / flu-like illness
- pyrexia
- rhinorrhoea +/- green / yellow discharge
- headache / facial pain (in area of affected sinus)
- blocked nose
when is headache / facial pain worse in acute sinusitis?
on leaning forward
what are ostia?
small channels in which paranasal sinuses drain in nasal cavity (commonly middle meatus)
what are conditions which may block ostia of sinuses?
e.g. nasal polyps
what increases the risk of sinusitis?
deviated septum
what is another cause of sinusitis?
dental infection (involving upper teeth)
how is acute sinusitis usually treated?
normally self-limiting
usually 1 week, sometimes 2-3 weeks
what can primary (viral) infection e.g. rhinitis lead to?
reduced ciliary function,
oedema of nasal mucosa and sinus ostia,
therefore: increased nasal secretions
what is impeded in acute sinusitis?
drainage from sinus
what can stagnant secretions within the sinus in acute sinusitis lead to?
ideal breading ground for bacteria-secondary infection
commonly strep / haemophilus
what are symptomatic treatments of acute sinusitis?
nasal decongestants (from increased secretions) pain killers may be helpful
what is done in severe / prolonged episodes of acute sinusitis?
antibiotics may be given
what is the nerve innervation of nasal cavity and paranasal sinuses to the antero-superior portion? including what?
including most of PARANASAL sinuses:
ophthalmic nerve (CN V1/a)
branches of ophthalmic artery (anterior + posterior ethmoid)
what is the nerve innervation of the nasal cavity and paranasal sinuses to posterio-inferior portion? including what?
including MAXILLARY sinus:
maxillary nerve (CN V2/b)
branches of maxillary artery (sphenopalatine artery)
what is sphenopalatine artery’s origin?
external carotid > maxillary > sphenopalatine
what are anterior and posterior ethmoidal arteries’ origin?
inferior carotid > ophthalmic artery > anterior and posterior ethmoidal arteries
management of epistaxis?
initial: pinching Kisselbach’s area
later: merocel nasal tampon
