Class notes ears Flashcards
Overall ear function:
hearing; equilibrium
External auditory canal terminates at the?
Tympanic membrane (TM)
Internal ear is made of?
Outer 1/3 is cartilage
Inner 2/3 tunnels through temporal bone
tympanic mem. separates?
TM separates external and middle ear.
Lymphatic drainage of external ear flow is?
to the parotid, mastoid, and superficial cervical nodes
Middle ear is:
Air-filled cavity inside temporal bone
Eustachian tube
connects middle ear with nasopharynx and allows passage of air. Normally closed—opens with swallowing or yawning.
3 functions of middle ear:
Conducts sound vibrations from outer to inner ear.
Protects inner ear by reducing sound amplitude.
Eustachian tube allows equalization of air pressure on each side of the TM so TM does not rupture.
Inner ear contains:
Contains bony labyrinth which holds sensory organs for equilibrium and hearing.
Cochlea contains:
contains central hearing apparatus (inner ear)
Function of hearing (3 levels):
peripheral; brainstem; cerebral cortex
Peripheral level:
Sound transmission
Vibrations converted into electrical impulses for analysis by the brain.
Electrical impulses conducted by the auditory portion of CN VIII to the brainstem.
Brainstem function:
binaural interaction—locating direction of sound in space—identifying the sound
Cerebral cortex:
interprets the meaning of the sound and begins the appropriate response.
Normal pathway of hearing is
by air conduction.
Alternative route is
by bone conduction (through vibration of skull bones).
Conductive loss caused by:
impacted cerumen; foreign body; perforated TM; pus/blood in middle ear; otosclerosis (↓ mobility of the ossicles). Can by treated by increasing amplitude.
Sensorineural (perceptive) loss caused by:
patho of inner ear, CN VIII, or auditory areas of cerebral cortex; gradual nerve degeneration that occurs with age.
Three semicircular canals (labyrinth) in inner ear function:
input to brain about your postion in space
Inflamed labyrinth causes:
wrong signals to brain—vertigo
Infants and young children eustachian tube is:
shorter, wider, more horizontal
Cause of otitis media in children:
shorter, wider, more horizontal eustachian tube
easier for pathogens from nasopharynx to get to the middle ear,
Increased risk for middle ear infection in children:
Absence of breastfeeding first 3 mo. of life Exposure to secondhand smoke Daycare attendance Male sex Pacifier use Seasonality (fall, winter) Bottle feeding in the supine position
For ear symptoms obj data:
Ask about recent URI, history of ear infections
Otalgia is:
earache
Otorrhea is:
ear discharge?
tinnitus is:
ringing in the ears
caused by noise-induced hearing loss.
Other causes include: ear infections, disease of the heart or blood vessels, Ménière’s disease, brain tumors, emotional stress, exposure to certain medications, a previous head injury, and earwax
What increases risk for recurrent OM in children?
First episode of OM that occurs within first 3 mo. of life
Infants at risk for hearing deficit are those who were/have:
Exposed to maternal rubella Exposed to maternal ototoxic drugs in utero Premature infants Low birth weight infants Trauma or hypoxia at birth Congenital liver or kidney disease
Children at risk for hearing deficit are those who have:
Meningitis Measles Mumps OM Any illness with persistent high fever
Incidence and severity of OM increased in indigenous children from:
No. America, Australia, New Zealand, and Northern Europe.
Aging adult may have increased amount and drier ____ , which become impacted
cerumen
Presbycusis is:
gradual sensorineural loss caused by nerve degeneration in the inner ear
Presbycusis in aging adult: % and age:
hearing loss in 60% older than 65 years
Clues to hearing loss:
Lip reading Frowns, leans forward to hear Postures head to catch sound Misunderstands questions Frequently asks you to repeat questions Acts irritable or startled when you raise your voice Speech is garbled Inappropriately loud voice Flat, monotonous tone of voice
Testing hearing acuity in newborn:
Newborn: startle (Moro) reflex; acoustic blink reflex
Testing hearing acuity 3-4 m:
Acoustic blink reflex; Infant stops moving and appears to “listen”. Stops sucking. Quiets if crying. Cries if quiet.
Testing hearing acuity in 6-8m:
Infant turns head to localize
Testing hearing acuity in preschool/school-age:
need to screen with audiometry
In infants, children, and adults, how can hearing loss affect quality of life
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