ear disease (see DM) Flashcards
what section of the ear is the tympanic membrane part of
the middle ear - although embryological is is both middle and external ear
what is migration (ear)
the outer layer of the skin lining the ear canal very gradually migrates outwards -> this is how wax and dead skin is naturally removed from the canal
function of the Eustachian tube
equalise the pressure between the middle and outer ear
what epithelium lines the middle ear
respiratory epithelium
what nerve traverses the middle ear
chorda tympani (branch of CN VII) => facial nerve palsies can arise due to ear surgery
what nerves innervate the inner ear
- The auriculotemporal nerve (branch of CN V mandibular) - general sensory innervation to the meatal side of tympanic membrane
- vagus nerve (CN X) - general sensory innervation to the meatal side of tympanic membrane
- The tympanic branches of the glossopharyngeal nerve - general sensory impulses of the mucosal side of the tympanic membrane transmitted
what are the 5 main symptoms of ear disease
- hearing loss
- otalgia (pain)
- otorrhoea (dishcarge)
- vertigo
- tinnitus
what other class of disease can affect the external ear
derm diseases -> the external ear is skin lined and so may present w itchiness, redness, scales, lumps, ulcerations and even skin cancers
5 acquired diseases of the external ear
- haematoma
- exostosis (benign outgrowth of cartilaginous tissue on a bone)
- osteoma
- infection
- foreign body
4 common external ear dformaties
- prominent cup - abnormally protuding ear, may have an incomplete opening of the ear (cup ear deformity)
- stahl’s ear - helix not formed properly, often in combination w other deformities
- lidding/lop ear - folding over the helical rim/upper third of the ear
- helical rim deformity - irregularities or compressions that may occur anywhere along the helix
what is microtia and what are the grades
a congenital condition in which the cartilage of the outer ear is underdeveloped or absent (but normal middle + inner ear)
grade 1 - small but almost normal
grade 2 - some recognisable anaotmy present
grade 3 - small rudiment of soft tissue and no ear canal
grade 4 - no external ear and no ear canal
congenital abnormalities of the external ear (3)
- microtia
- pinna abnormalities
- external canal stenosis
what is an auricular haematoma an what is the consequence of this
the stripping of the perichondrium off the cartilage by blood => nutrients and oxygen can’t reach cartilage (it is avascular itself) -> ischaemia and necrosis leading to permanent deformity
what is perichondritis
an infection of the skin and tissue surrounding the cartilage of the outer ear -> just the cartilaginous part, sparing of the lobe and tragus
what is acute otitis externa
inflammation of the external auditory meatus lasting <6wks
2 common causes for otitis externa
- self cleaning -> cotton buds leading to trauma or foreign body blockage
- swimming (swimmer’s ear -> diffuse bacterial otitis externa)
2 common bacteria causing otitis externa
- pseudamonas aeruginosa
- staphylococcus aureus
what is furunculosis (ear)
acute localised otitis externa
what is otomycosis
fungal otitis externa
what is a severe complication of otitis externa
necrotising otitis externa
what is chronic otitis externa
inflammation of the external ear lasting >3 months