Hearing Practical Flashcards
What do you use otitis media
Grommits used to treat inner ear infection
What is conductive hearing loss
Loss of stereocilia (hair cells)
What is sensoineural hearing loss
Issue with spinal ganglia (nerves)
Describe Rinne’s test method
Strike the tuning fork to get it vibrating. Place the end of the stem on the mastoid bone until the sound becomes inaudible. Bring the fork close to the hear canal and listen
Describe Rinne’s test results
If the sound appears louder on the bone than the air it indicates conductive hearing loss. You would get a positive result in sensorineural hearing loss
Describe Weber’s test method
Strike the tuning fork so that it is vibrating and place the stem against the vertex of the skull
Describe Weber’s test results
In normal hearing you can hear the sounds equally in both ears. In sensorineural hearing loss the sound is louder in the ear that isn’t affected (normal ear). In conductive hearing loss the sound is louder in the ear that has conductive hearing loss (quieter in the normal ear)
What do you need to determine if someone has sensorineural or conductive hearing loss
A combination of results from both Weber’s and Rinne’s tests
What is presbycusis
Age related deafness
What are the features of presbycusis
Lose higher frequencies, range is now more to do with consonants
What natural mechanism protects the ear from loud noise
Stapedius contracts
Why is stapedius contracting not effective for a gun shot
It is for continuous and loud noise, not sudden
Which frequency is the stapedius contraction most effective for
Low frequencies
How long can a person spend in an environment of 85 dB
8 hours
How do you work out how long someone can spend in an environment
8 divided by 2 to the power of (ndB-81)/3. ndB is the number of dB
Which bone contains inner ear
Pectous part of temporal bone
What effects does severing the corda tympani have
Bell’s palsy and loss of taste
What is the role of the ear ossicles
Reduces amplitude, increases pressure, allows for impedence matching i.e. transduction of sound from air filled middle ear to fluid filled inner ear
What is the role of the round window
Fluid in the inner ear is compressible. Vibrations of the scapes pushes into the tympanic membrane which pushes into the round window which acts as a pressure release valve so that waves can propagate to the organ of corti
How does the fluid composition in the scala vestibuli and scala tympani differ from the scala media
Scala vestibuli and scala tympani contain perilymph which has more sodium and less potassium. Scala media contains endolymph which has more potassium and less sodium
Describe the endocochlear potential
Endolymph secreted fluid high in potassium so that potassium concentration is higher outside the hair cells than inside so that when potassium channels open in response to sound potassium is released into the cell resulting in an action potential
What secretes potassium into the endolymph
Stria vascularis
What is the role of the inner hair cells
Transfer sound waves in the fluid of the cochlear into electrical signals. Detect waves as sound and send this information to the CNS via electrical signals
What is the role of the outer hair cells
Amplifier
What is ototsclerosis and what type of patient is most likely to be susceptible
Calcification of the ossciles. Women 15-35 most vulnerable, can be brought on by pregnancy
Under what circumstances are cochlear implants an appropriate treatment
When hair cells are damaged but the nerves (spinal ganglia) are still intact
Why can cochlear implant use in young children raise ethical issues
They can be cut off from the silent community
What ability do Wernicke’s and Broca’s areas support
Linguistics
What artery supplies Wernicke’s and Broca’s area
Middle cerebral artery
How would the consequence of stroke damage to the middle cerebral artery on the left side differ from the same lesion on the right
No linguistic problems caused by a lesion on the right
Why is gentamicin prescribed in endocarditis
It is an antibacterial which can be used to treat the bacterial infection endocarditis
