Physiology and clinical aspects of hearing and balance Flashcards
Does the middle ear transform acoustic energy from the medium of fluid –>air or air–>fluid?
air –> fluid
middle ear should be air - atmospheric pressure
inner ear (cochlear) - fluid filled
How does the middle ear act as a sound amplifier?
area effect of tympanic membrane
lever action of ossicular chain
What type of hearing loss do otitis media, perforation of ear drum, eroded incus and otosclerosis cause?
conductive hearing loss
otitis media with effusion - what is the problem with this?
middle ear filled with fluid
middle ear works optimally with being air filled to facilitate better pushing of ear drum
What is a hole in the ear drum called?
perforation
What can cause an eroded incus?
chronic infection eg vasculitis
What part of the middle ear does otosclerosis most commonly affect?
stapes footplate
What is otosclerosis?
bony deposition in the annular ligament
2 parts of the cochlea
scala vestibule
scala tympani
The part of the basilar membrane which vibrates more is in relation to what?
frequency
What do assessments of hearing loss determine?
degree of hearing loss
describe the 2 tuning fork tests
webers - test of lateralisation, midline and assess hearing comparison on both sides which should be equal
rinne’s - compares loudness of perceived air conduction to bone conduction in one ear at a time
puretone audiometry
air conduction to determine faintest sounds heard at different frequencies
earphones worn
What is presbyacusis?
age related hearing loss
tympanometry - what does it measure, detect and how?
measures mobility of the ear drum
pushes air pressure into ear canal causing the drum to move
detect wax, fluid and perforation
What are autoacoustic emissions?
sounds given off by the inner ear when the cochlea are stimulated by a sound
the hair cells vibrate and measured with a probe
Auditory brainstem response
cochlea and brain pathways used with disabled/young
electrodes on the head record brain wave activity in response to sound
Hearing aid - parts, what frequencies used for and how is it operated?
speaker, microphone, amplifier, ear hook and mould
low and mid frequencies
battery operated
What type of hearing aid is used for high frequencies?
open fit
Bone anchored hearing aid
through the bone and into the inner ear to bypass the external and middle ear in conductive hearing loss
name the 2 hearing implants
middle ear and cochlear
name the 3 parts of the inner ear concerned with balance
utricle, saccule and semi circular canals
What do utricle and saccule detect?
utricle - horizontal
saccule - vertical
how are the cilia arranged in the otolith organ?
sensory epithelium with cilia in a gel matrix with calcium carbonate crystals on top
What is the vestibule-ocular reflex?
stabilises gaze by moving eyes in order to compensate for head and body movements
fixes image on retina for clear sight
What are the 3 body balancing regulating inputs?
peripheral vestibular apparatus
visual
pressure
Ear conditions affecting balance (3)
benign paroxysmal positional vertigo
vestibular neuritis
Meniere’s disease
BPPV - what causes it, diagnosis and treatment
utricle crystals float into semicircular canal
dix hallpike test and Epley manoeuvre
Vestibular neuritis cause
reactivation of latent virus eg HSV causing neuritis of vestibular nerve
Meniere’s disease cause
increase in endolymph
Non ear common condition causing balance problems
migraine
