N202 Ears and Hearing
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Name 3 parts of the ear
External, middle and inner ear
Name 3 parts of the external ear
auricle, external auditory canal, and tympanic membrane
Name 5 parts of the auricle (pinna)
helix, antihelix, tragus, antitragus, and lobe
How long is the External Auditory canal
2.5 to 3 cm long (terminates at the Tympanic membrane)
What is cerumen?
- yellow waxy substance that lubricates
- & protects the ear (ear wax); secreted by glands in the EAC
What is the tympanic membrane?
separates external ear canal from middle ear; ear drum
What is the normal color of the TM?
translucent; pearly gray
Name 7 landmarks of the tympanic membrane.
- Prominent cone of light (5 o’clock in
- right ear; 7 o’clock in left ear)
- Short process of malleus
- Manubrium (handle of malleus)
- Umbo (tip of malleus)
- Pars flaccida (slack superior section above the short process)
- Pars tensa (taut section)
- Annulus (fibrous outer ring)
Where is the middle ear located?
Air cavity inside temporal bone
Name 3 structures of the middle ear
malleus, incus, and stapes
What are 2 purpose of the middle ear?
- Equalizes pressure (opens to nasopharynx via eustachian tube)
- Conducts sound vibrations to inner ear
What is contained in the inner ear?
sensory organs for equilibrium and hearing
what structures are in the inner ear?
(vestibule, semicircular canals, cochlea)
What is the purpose of the Organ of corti
- transmits sound impulses to the 8th
- cranial nerve
What is the process behind hearing?
- Sound is transmitted through the
- external auditory cannel to the TM
- • Vibrations of the TM are transmitted by
- the middle ear bones to the oval window
- • From here, sound is transmitted to the
- sensory organs of the inner ear where the round window disperses the vibrations
- • Lastly, vibrations are converted to
- nerve impulses which are conducted by the 8th cranial nerve to the temporal lobe of the brain for
- interpretation of sound
List 2 types of conduction of sound
Air conduction and bone conduction
What is air conduction?
usual mechanism of hearing- most effective (Sound is transmitted through the external auditory cannel to the TM )
What is bone conduction?
- alternate route via vibration of skull
- bones (transmits sound directly to the
- inner ear & CN 8)
What is conductive hearing loss?
- obstruction in the external or middle
- ear); caused by cerumen, foreign body, perforated TM, fluid in middle ear, otosclerosis
What is sensorineural loss?
- pathology in the inner ear, CN 8, or
- auditory areas of the temporal lobe
- •presbycusis - gradual nerve degeneration (occurs with aging)
What is mixed hearing loss?
combination of conductive & sensorineural; e.g., presbycusis & ear wax
What is the purpose of the labyrinth in the ear?
constantly sends info regarding body position to the brain
What is vertigo?
Whirling sensation, staggering gait; caused by inflammation
When does a fetus develop its inner ear?
What disease during the first trimester damages the organ of corti in the fetus
When does a child develop an acoustic blink reflex
What is an acoustic blink reflex
infant stops movement & appears to listen
What age does a child "turn head to localize sound"
Why are children at higher risk for ear infections
shorter and wider eustachian tube
What are 4 signs of hearing loss in children?
- • Reacts more to movement & facial
- expression than to sound
- • Speech is monotonous or garbled;
- mispronounces sounds
• Appears shy & withdrawn
What is related to decreased hearing in aging adults?
- increase coarseness of cilia lining ear
cerumen is drier and more occlusive d/t atrophy of the apocrine glands
What is presbycusis?
• Begins when a person is in the 40s
- High frequency sounds are lost 1st (shouting increases high frequency &
- makes hearing worse)
Harder to hear consonants (speech may sound garbled)
Hearing difficulty increases with background noise
What are indications of hearing loss?
Inattentive in casual conversation
- • Lip reading (watching lips rather than
- • Facial expression is strained or
- • Posturing head (to hear sounds with the
- better ear)
- • Misunderstanding questions - confuses
- words that sound alike
- • Frequently asks to have statements
- • Speech sounds garbled &/or vowel
- sounds distorted
• Inappropriately loud voice
• Flat monotonous tone of voice
- • Hears better when the environment is
List types of ear wax (based on culture)
- • Moist/honey colored (African Americans
- & Caucasians)
Dry/flaky (Asians & Native Americans)
Who has increased incidence of middle ear infections?
- Native Americans, Alaskan & Canadian
- Bottle feed babies (lying down with bottle increases reflux through eustachian
- tube to middle ear)
What is tinnitus?
(ringing, crackling, buzzing)
Often 1st sign of hearing loss
Worse at night "white noise" (when room is quiet)
What is microtia?
small ears <4cm
What is macrotia?
large ears >10cm
How should the pinna be positioned?
- the top of the pinna should touch (or be above) an imaginary line drawn
- from the inner canthus of the eye to the most prominent area of the occipital bone
the tilt of the pinna should be within 10o of vertical
abnormal positioning may indicate a chromosomal abnormality & GU problems
What are Darwin tubercles?
painless nodule on helix = norm variation)
Tophi: yellow non tender nodules on helix 2o to gout (contain uric acid crystals)
What is indicated with a tender pinna
What is indicated with a tender/painful tragus?
What is indicated with pain/tenderness when pressing the mastoid
What are signs of mastoiditis?
painful, swollen, erythematous mastoid region
How should the ear be positioned (for each age group) for an otoscope exam?
- Adult- hold ear up and back
- child under 3 yo- hold ear down
What are signs of otitis externa?
- watery discharge, sometimes
- serosanguineous, pruritic) – commonly d/t pseudomonus & fungus
what would clear fluid s/p head trauma indicate when inspecting the ear.
(may be CSF from basilar skull fracture)
Test fluid for glucose (via test strip) – positive glucose = CSF
Needs immediate attention (increased risk of meningitis)
What is a furuncle?
boil from infected hair follicle
What is atresia?
absence or closure of ear canal?
What is exostosis?
small hard bony nodules in ear canal)
hypertrophic bone which is more common in cold water swimmers
benign--doesn’t require treatment
What is the annulus?
fibrous outer ring of TM
Where can the cone of light be seen?
triangular reflection on TM;
RT ear (5 o’clock)
LT ear (7 o’clock)
What is the indication of a retracted drum?
- vacuum in middle ear from blocked eustachian
- tube &/or serous otitis media
- evidenced by prominent landmarks,
- distorted or absent light reflex, decreased mobility of drum
What are signs of serous otitis?
Yellow-amber color TM
Air bubbles behind drum
What are signs of otitis media?
• Bright red TM
Loss of landmarks
- Symptoms of acute TM perforation
- (1)Ear pain
- (2) Pain stops with popping sensation
- (3)Purulent drainage seen in ear canal
What is the Weber test?
- Place the tuning fork on top of head
- (should hear sound in both ears equally) – describe as “sound equalizes bilaterally”
- • Conductive Loss (sound lateralizes to
- the “bad” ear)
- With a blocked ear drum, the outside noise does not mask sound, thus, sound is conducted through bone to the “bad” ear.
- (e.g., otitis media)
• Sensorineural Loss (sound lateralizes to the “good” ear)
Sound lateralizes to the good ear when the “bad’ ear can't conduct sound (either by bone or air conduction)
- • If sound goes to the good ear—that’s
- bad (this indicates that the bad ear is not conducting sound (through bone or air) & may
- have a sensorineural problem
- • If sound goes to the bad ear—that’s
- good (this indicates that the bad ear is able to conduct sound and does not have a sensorineural
How is the rinnae test conducted
• Place the tuning fork over the mastoid bone, then at the external auditory canal
• Norm: AC > BC (~ 2 : 1)
• Conductive Loss: BC > AC (can't hear sound when tuning fork is placed by external ear canal)
• Sensorineural Loss: AC > BC (but, both are diminished)
What is Romberg test?
tests cerebellum proprioception (vestibular apparatus in inner ear)
- Stand with feet together, arms at sides, eyes closed approx 20 sec.
- Observe balance
Positive Romberg = unsteady balance (falling out of stance)
What is an acoustic neuroma?
benign tumor on the acoustic nerve
What is otosclerosis?
- • Hereditary
- condition resulting in fixation of the stapes (doesn’t conduct sound through oval window to inner ear)
SXS: tinnitis, progressive conductive hearing loss
Occurs in late teens to early 30s
What is labyrithitis
inflammation of the labyrinth of inner ear (may cause total sensorineural hearing loss on the affected side)
complication of URI
S/S: vertigo (increases with head movement) & nystagmus
What is Meniere Disease?
• affects the vestibular labyrinth leading to profound sensorineural hearing loss
SXS: attacks of vertigo, tinnitis, progressive hearing loss
Unilateral or bilateral
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