List the 3 fxns of the middle ear
1- conducts sound vibrations from the outer ear to the central hearing apparatus in the inner ear
2-protects the inner ear by reducing the amplitude of loud sounds
3-its eustachian tube allows equalization of air pressure on each side of the tympanic membrane
Contrast the 2 pathways of hearing
(AC) Air conduction- most efficient
-vibrations (sound waves produce with tympanic membrane) carried by middle ear ossicles to oval
window
(BC) Bone conduction- bones of the skull vibrate and these vibrations are transmitted directly to the
inner ear to the CN VIII
Differentiate among the types of hearing loss and give examples
-Conductive: mechanical dysfunction of the external or middle ear
--> partial loss bc person is able to hear if sound amplidtude increases enough to reach nerve ending
-->CAUSES: impacted cerumen, foreign bodies, perforated tympanic membrane, pus or serum in the
middle ear, or otosclerosis
-Sensorineural(perceptive): pathology of the inner ear, CN VIII, or the auditory areas of cerebral cortex
-->increasing amplitude may not enable person to understand words
--> CAUSES: prebycusis, ototoxic drugs
-Mixed: Combination
Relate the anatomic differences that place the infant at greater risk for middle ear infxns
-The infant's eustachian tube is relatively shorter and wider, and its position is more horizontal. therefore
it is easier for pathogens from the nasopharynx to migrate through middle ear
Positioning of normal ear alignment in the child
External ear canals are shorter and have a slope
otosclerosis
gradual bone formation that causes the footplate of the stapes to become fixed in the oval window
presbycusis
Gradual sensorineural loss caused by nerve degeneration in the inner ear that slowly progress
-->occurs with 60% of >65 year olds
Contrast the motions used to straighten the ear canal when using the otoscope with an infant versus an
adult
INFANT: pull pinna straight down
ADULT: pull pinna up and back
Describe the appearance of these nodules that could be present on the external ear:
Darwin's tubercle
sebaceous cyst
tophi
chondrodermatitis
keloid
carcinoma
Darwin's tubercle-small painless nodule at helix
sebaceous cyst- commonly behind lobule in the post auricular fold
-->filled with sebaceous material and can be painful if infected
tophi- small, whitish, yellow, hard, nontender nodules in or near helix
-->contains greasy, chalky, material
chondrodermatitis- painful nodules develope on rim of helix
-->small, indurated, dull red, poorly defined and very painful
-->result of repetitive mechanical pressure or environmental trauma (sunlight)
keloid- overgrowth of scar tissue which invades original site of trauma
carcinoma-ulcerated, crusted nodule with indurated base that fails to heal
-->bleeds intermittenly
Describe the appearance of these conditions that could appear in the ear canal:
osteoma
exostosis
furuncle
polyp
osteoma- single, stoney hard, rounded nodule that obscures the drum
-nontender, benign
exostosis- small, boney hard, rounded nodules of hypertrophic bone, convered with normal epithelium
-frequently in cold water swimmers
-no treatment needed but can cause cerum accumulation
furuncle- PAINFUL. reddend, infected hair follicle
polyp-arises in canal from graulomatous (mucosal tissue) redder then surrounding skin. bleeds easily
-indicates chronic ear disease
-Benign!
annulus
outer fibrous rim encircling the eardrum
atresia
congenital absence or closure of ear canal
cerumen
yellow waxy material that lubricates and protects the ear canal
cochlea
inner ear structure containing the central hearing apparatus
Eustachian tube
connects the middle ear with the nasopharynx and allows passage of air
helix
superior posterior free rim of the pinna
incus
"anvil"
middle of the 3 ossicles of the middle ear
malleus
"hammer"
first of the 3 ossicles of the middle ear
mastoid
bony prominence of the skull located just behind the ear
organ of corti
sensory organ of hearing
otalgia
pain in the ear
otitis externa
inflammation of the outer ear and ear canal
otitis media
inflammation of the middle ear and tympanic membrane
otorrhea
discharge from the ear
pars flaccida
small, slack, superior section of tympanic membrane
pinna
auricle or outer ear
stapes
"stirrup"
inner of the 3 ossicles of the middle ear
tinnitus
ringing in the ears
tympanic membrane
"eardrum"
thin, translucent, oval membrane that stretches across the ear canal and separates the middle ear from
the outer ear
umbo
knob of the malleus that shows through the tympanic membrane
vertigo
a spinning, twirling sensation
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