13 - Anatomy of the Ear Flashcards
What can be some signs and symptoms of ear disease?
How can the different parts of the ear be split up?
External, Middle, Inner
What nerves carry general sensation to the ear and why is this important?
- Referred pain to the ear for lots of disorders
- CN VIII carries special sensory
If you had otalgia but a normal ear examination what are some differentials you can suspect?
-
What is the function of the external ear?
What are some causes of pinna abnormalities and using the pictures what would be the diagnosis?
What is Ramsey Hunt syndrome?
- Shingles of the facial nerve (V.Zoster)
- Facial nerve palsy always check ear
What can be the complications of a pinna haematoma and how do you treat it?
- Blunt injury can cause subperichondrial haematoma, stripping perichondrium and blood supply from cartilage
- Pressure necrosis
- Need to drain and reappose two layers using rolls otherwise will get fibrosis and asymmetrical cartilage formation so cauliflower ear
What is the structure of the external acoustic meatus?
- Lined with same epithelia as skin to lateral surface of tympanic membrane
- Outer third cartilage, inner two thirds bony
- Sigmoid so pull back, up and out to straighten to see tympanic membrane
- Hair, sebaceous and ceruminous glands on cartilage part not bony
- Epithelial migration to clean
Label the following pathology of the tympanic membrane.
What is the angle of the tympanic membrane normally and what is some pathology that can affect this angle?
If you see this when examining a tympanic membrane what should you suspect, and what is the pathogenesis of this disease?
Cholesteatoma
- Chronic ET dysfunction causes -ve pressure to pull pocket into middle ear as no equillibrium of pressure
- Retraction of pars flaccida forms pocket trapping keratin and stratified sqaumous epithelium which proliferates and forms cholesteatoma
- Painless, smelly ottorrhea +/- hearing loss*
- Slow grows and can enzymatically destroy bones like ossicles, mastoid, cochlea to brain
What is the function of the middle ear?
- Amplify and vibrate fluid from TM to oval window of cochlea
- Ossicles connected by synovial joints and tampered by tensor tympani and stapedius in accoustic reflex
What nerves are involved in the acoustic reflex?
What is otosclerosis?
- Common cause of acquired hearing loss in middle ear in young adults, ?genetic and environmental viral causes
- Ossicles fuse at articulations due to abnormal bone growth, usually at base plate of stapes
- Sound vibrations cannot be transmitted as well
- Gradual uni/bilateral conductive hearing loss
What are some symptoms of otosclerosis?
- Usually bilateral
- Will become totally deaf if not treated
Why is there a negative pressure in the middle ear and how is this equalised with atmospheric pressure?
What is the presentation and treatment of otitis media with effusion?
- Not infection (glue ear)
- ET dysfunction so fluid and pressure in middle ear so hearing issues
- Resolve spontaneously within 2-3 months or if affecting S+L or persisting put grommets in untill they fall out
What is the presentation and cause of acute otitis media?
- Usually viral but give delayed prescription for antibiotics in case bacteria
- S.Pneumoniae and H.Influenzae common
Why are children more susceptible to middle ear infections and glue ear?
What are some complications of acute otitis media?
- TM popping with lots of discharge
- Facial nerve involvement (chorda tympani and nerve to stapedius) as runs with middle ear
What is mastoiditis, how does it present and how do you treat it?
Middle ear cavity communicates via mastoid antrum with mastoid air cells so can cause spread of infection
IV antibiotics
What is the function of the inner ear (labyrinth) and what can inner ear pathology present with?
- Hearing: cochlea converts endolymph movement into action potentials CNVIII
- Position and balance: vestibular apparatus lined with hairs convert endolymph movement.
- External and middle ear pathology have no issue with balance and position
How do we hear?
- Auricle and external auditory canal focus and funnel sound waves to TM which vibrates
2. Stapes vibrates on oval window so movement of fluid in cochlear
- Fluid movement sensed by stereocilia in cochlear duct (spiral organ of corti)
- Movement of fluid triggers action potentials in cochlear part of CN VIII
5. Primary auditory cortex in temporal lobe
What is the vestibular apparatus made up of?
What is presbycusis?
- Sensorineural hearing loss associated with old age
- Bilateral and gradual
- Treated with hearing aids
What is benign paroxysmal positional vertigo?
- Vertigo
- Short lived (seconds) triggered by movement of hear, e.g turning over in bed
- Due to crystals in semicircular canal getting dislodged and causing fluid movement
- Dix Hallpike (with nystagmus) and Epley maneouvre to diagnose and treat
What is Meniere’s disease?
- Vertigo, hearing loss and tinnitus (usually unilateral)
- Aural fullness and nausea/vomiting
- Longer lasting 30 mins - 24 hours
- Recovery in between
- Hearing may deteriorate over time
What is acute labrynthitis?
- History of URTI
- Involves all inner ear structures so hearing loss, tinnitus, vomiting, vertigo
What is acute vestibular neuronitis and how does it differ to acute labrynthitis?
- History of URTI
- Usually suddent onset of vomiting and severe vertigo for days but no hearing disturbance like in AL
What should you do if a patient presents with hearing loss?
What is the difference between conductive and sensorineural hearing loss?
How do you figure out if a patient’s hearing loss is sensorineural or conductive?
Webers and Rinnes test
Label the following parts on the ear.
What carries general sensation from the middle ear?
- Middle ear lined with respiratory epithelium
- Sensory via glossopharyngeal nerve
What triggers stereocilia to fire an action potential?
- Utricle and saccule: rotational acceleration and static pull of gravity
- Semicircular canals: rotational acceleration in three planes
Where is the oval and round window?
Label this normal tympanic membrane and explain how you would carry out an exam with an otoscope?
- Inspect pinna and mastoid and palpate
- Pull pinna out, up and back
- Should be translucent pearly grey and oblique
- If dull, red, yellow or bulging or white plaque (tympanosclerosis) then not normal
Why does conductive hearing loss lead to hearing a louder noise in the affected ear on the Weber’s test?
There is no background noise dampening the sound down as ear is blocked
What is the most likely causative organism in a middle and external ear infection?
Middle: H.Influenzae or S.Pneumonia
Outer: P.Aeruginosa then Staph aureus
What are the three common courses of vertigo and how can you choose which one is the cause?
When looking at the tympanic membrane how can you tell if it is a left or right ear?
- Cone of light
- If points to 5 o clock it is right ear
- If points to 7 o clock it is left ear
