Lab 5 Flashcards
3 ossicles of the inner ear
MIS malleus, incus, stapes
list flow of sound to brain
sound –> ear canal –> tympanic membrane –> 3 ossciles –> oval window –> vibration of fluid in cochlea –> round window aids vibration –> hair cells vibrate –> mechanically gated ion channels open –> AP generated to cochlear nerve –> cranial nerve 8 to brain
name of nerve carrying sound to brain
cranial nerve 8 = vestibular cochlear nerve
purpose of ossicles
amplify vibration caused by sound - especially stapes
name of middle ear infection, why, and what it can cause
otitis media, eustachian/auditory tube conncts pharynx to middle ear so upper respiratory infections can easily lead to middle ear infections
vestibular apparatus
sends information about relative body position of the entire body
Rinne test how to do
strike tuning fork –> hold against mastoid process of temporal bone –> wait until sound no longer heard –> hold near ear and ask if sound is still heard
positive Rinne test and meaning
normal! air conduction > bone conduction, sound is heard when bringing it to ear
negative Rinne test and meaning
abnormal, sound is not heard again after bringing it to ear, indicates conductive hearing loss
conductive hearing loss meaning and causes
air conduction < bone conduction, problem with outer ear, middle ear, oval or round window and vibrations
webers test how to do
hit tuning fork –> place on top of skull –> see if sound is conducted through bone evenly on both sides
lateralization of webers test meaning
right/left lateralization means sound is heard LOUDER on that side
2 explanations for lateralization in webers
- ear that hears louder has conductive hearing loss (sound gets trapped, background noise is cancelled, ear becomes more sensitive to bone conduction)
- sensorineural hearing loss on quieter side
weber lateralized to the right and Rinne negative on the right
conductive hearing loss on right
Weber no lateralization and Rinne positive bilaterally
normal or sensorineural hearing loss equal on both sides
weber lateralized to the right and Rinne positive bilaterally
sensorineural hearing loss on left
weber no lateralization and Rinne negative bilaterally
conductive hearing loss on both sides
cochlear implant - how it works and what it treats
generates electrical signals, treats conductive hearing loss although cochlear nerve still has to work, mimics hair cells which generate AP
hearing aid - how it works and what it treats
makes sound louder, treats conductive hearing loss
24 year old who listens to loud music - what type of hearing loss?
sensorineural hearing loss
child with otitis media and hearing loss - what type of hearing loss
conductive hearing loss
pathway of light through 3 main parts of the eye
light –> pupil –> lens –> retina
visual acuity
sharpness and clarity of the image
myopia
nearsightedness, eye ball is too long, image falls in front, object must be brought closer to see
hyperopia
farsightedness, eye ball is too short image falls behind, object must be brought further away to see
presbyopia
caused by old age, lens is not flexible enough so accommodation to see close object fails, reading glasses needed
accommodation
ability of eye to change curvature of lens to see close/far objects clearly
astigmastism
abnormal curvature of lens, creates distorted vision, also corrected with glasses
20/40 meaning
you see clearly at max 20 feet what others see clearly at max 40 feet
snellen chart - how to do
person stands 20 feet away, read line with one eye at a time then both
blind spot cause
optic nerve leaves at optic disc, no photoreceptors there
why are we not aware of blind spot
small, located at peripheral vision, brain join eye from both eyes and resolves the blind spot
2 point discrimination / threshold test - how to do
caliper with 2 points, decrease distance until only 1 point can be felt
meaning of 1 vs 2 point felt
1 point = points are on same receptor field, 2 points = on different receptor fields
purpose of 2 point discrimination test
measure receptor density
referred pain meaning
pain from an internal visceral organ is felt in another region of the body
cause fo referred pain
sensory neurons from visceral organ and other body parts synapse with the same interneuron so brain can’t distinguish the location its coming from
angina pectoris
heart pain/damage felt in chest wall or shoulder
phantom limb pain
amputation –> postcentral gyrus and sensory neuron cell body in spine still alive –> temperature, touch, stress activates neurons causing pain that seems to come from amputated limb
otosclerosis
calcification of ossicles caused by repeated otitis media, leads to conductive hearing loss
