N202 Ears and Hearing

External, middle and inner ear

auricle, external auditory canal, and tympanic membrane

helix, antihelix, tragus, antitragus, and lobe

2.5 to 3 cm long (terminates at the Tympanic membrane)

• yellow waxy substance that lubricates
• & protects the ear (ear wax); secreted by glands in the EAC

separates external ear canal from middle ear; ear drum

translucent; pearly gray

• 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)

Air cavity inside temporal bone

malleus, incus, and stapes

• Equalizes pressure (opens to nasopharynx via eustachian tube)
• Conducts sound vibrations to inner ear

sensory organs for equilibrium and hearing

(vestibule, semicircular canals, cochlea)

• transmits sound impulses to the 8th
• cranial nerve

• 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

Air conduction and bone conduction

usual mechanism of hearing- most effective (Sound is transmitted through the external auditory cannel to the TM )

• alternate route via vibration of skull
• bones (transmits sound directly to the
• inner ear & CN 8)

• obstruction in the external or middle
• ear); caused by cerumen, foreign body, perforated TM, fluid in middle ear, otosclerosis

perceptive loss;

• pathology in the inner ear, CN 8, or
• auditory areas of the temporal lobe
• •presbycusis - gradual nerve degeneration (occurs with aging)

combination of conductive & sensorineural; e.g., presbycusis & ear wax

constantly sends info regarding body position to the brain

Whirling sensation, staggering gait; caused by inflammation

4th week

rubella

3-4 months

infant stops movement & appears to listen

6-8 months

shorter and wider eustachian tube

Delayed speech

• • Reacts more to movement & facial
• expression than to sound

• • Speech is monotonous or garbled;
• mispronounces sounds

• Appears shy & withdrawn

• increase coarseness of cilia lining ear
• canal

cerumen is drier and more occlusive d/t atrophy of the apocrine glands

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

Inattentive in casual conversation

• • Lip reading (watching lips rather than
• eyes)

• • Facial expression is strained or
• puzzled

• • Posturing head (to hear sounds with the
• better ear)

• • Misunderstanding questions - confuses
• words that sound alike

• • Frequently asks to have statements
• repeated

• • Speech sounds garbled &/or vowel
• sounds distorted

• Inappropriately loud voice

• Flat monotonous tone of voice

• • Hears better when the environment is
• quiet

• • Moist/honey colored (African Americans
• & Caucasians)

Dry/flaky (Asians & Native Americans)

• Native Americans, Alaskan & Canadian
• Eskimos

Downs syndrome

• Bottle feed babies (lying down with bottle increases reflux through eustachian
• tube to middle ear)

Premature infants

earache

(ringing, crackling, buzzing)

Often 1st sign of hearing loss

Worse at night "white noise" (when room is quiet)

small ears <4cm

large ears >10cm

• 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

painless nodule on helix = norm variation)

otitis externa

otitis externa

otitis media

painful, swollen, erythematous mastoid region

• Adult- hold ear up and back
• child under 3 yo- hold ear down

• watery discharge, sometimes
• serosanguineous, pruritic) – commonly d/t pseudomonus & fungus

(may be CSF from basilar skull fracture)

Test fluid for glucose (via test strip) – positive glucose = CSF

Needs immediate attention (increased risk of meningitis)

boil from infected hair follicle

absence or closure of ear canal?

small hard bony nodules in ear canal)

hypertrophic bone which is more common in cold water swimmers

benign--doesn’t require treatment

fibrous outer ring of TM

triangular reflection on TM;


RT ear (5 o’clock)

LT ear (7 o’clock)

• 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

Yellow-amber color TM

Air bubbles behind drum

• 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

• 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
• problem)

• 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)

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)

benign tumor on the acoustic nerve

• • 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

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

• affects the vestibular labyrinth leading to profound sensorineural hearing loss

SXS: attacks of vertigo, tinnitis, progressive hearing loss

Unilateral or bilateral