EARS - Structure, Function, and Abnormalities

middle ear functions

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 so the membrane does not rupture

Branchial Remnant and Ear Deformity

A facial remnant or leftover of the embryologic branchial arch usually appears as a skin tag; in this case, one containing cartilage

fungal infection (otomycosis)

Colony of black or white dots on drum or canal wall suggests yeast or fungal infection

otosclerosis

Common cause of conductive hearing loss in young adults between ages of 20 and 40 years Gradual hardening that causes foot plate of stapes to become fixed in oval window, impeding transmission of sound and causing progressive deafness

scarred drum

Dense white patches on the eardrum are sequelae of repeated ear infections. They do not necessarily affect hearing.

pathway of hearing

Ear canal, tympanic membrane, ear bones, oval window, cochlear fluid/hair cells, brainstem (8th optic nerve)

furuncle

Exquisitely painful, reddened, infected hair follicle. May occur on tragus on the cartilaginous part of ear canal.

conductive hearing loss

Hearing loss or impairment resulting from interference with the transmission of sound waves to the cochlea

cellulitis

Inflammation of loose, subcutaneous connective tissue. Shows as thickening and induration of auricle with distorted contours

Otitis Externa (Swimmer's Ear)

Inflammation of the outer ear and ear canal due to infection

sebaceous cyst

Location is commonly behind lobule, in the postauricular fold. A nodule with central black punctum indicates blocked sebaceous gland. Filled with waxy sebaceous material and is painful if it becomes infected.

tuning fork test

Measures hearing by air conduction or bone conduction. Sound vibrates through the cranial bones to the inner ear.

cholesteatoma

Overgrowth of epidermal tissue in the middle ear or temporal bone may result over the years after a marginal TM perforation. it has pearly white, cheesy appearance

Chondrodermatitis Nodularis Helicus

Painful nodules develop on rim of helix (where there is no cushioning subcutaneous tissue) as a result of repetitive mechanical pressure or environmental trauma (sunlight). They are small, indurated, dull red, poorly defined, and very painful.

acute otitis media

Results when middle ear fluid is infected; absent light reflex from increasing middle ear pressure is early sign

Sensorineural (perceptive) hearing loss

Signifies the pathology of the inner ear, cranial nerve VIII, or the auditory areas of the cerebral cortex. a simple increase in amplitude may not enable the person to understand words

osteoma

Single, stony hard, rounded nodule that obscures the drum; nontender; overlying skin appears normal

Bullous Myringitis

Small vesicles containing blood on the drum; accompany mucoplasma pneumonia and virus infections

tophi

Small, whitish yellow, hard, nontender nodules in or near helix or antihelix; contain greasy, chalky material of uric acid crystals and are a sign of gout.

whispered voice test

Test one ear at a time while masking hearing in the other ear. Head should be 30-60cm from the person's ear, exhale and whisper slowly a set of 3 random numbers and letters, such as "5, B, 6". Normally person repeats correctly after you say it. -nonquantitative; this test documents the presence of hearing loss but does not measure the degree of loss.

carcinoma

Ulcerated, crusted nodule with indurated base that fails to heal. Bleeds intermittently

Darwin's tubercle

a small painless nodule at the helix. congenital variation and is not significant

basliar membrane

a structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid

macrotia

abnormally large ears

otitis media with effusion

amber-yellow drum suggests serum in middle ear that transudes to relieve negative pressure from the blocked eustachian tube

bone conduction (BC)

an alternative route of hearing where the bones of the skull vibrate. the vibrations are transmitted directly to the inner ear and to cranial nerve VIII

polyp

arises in canal from granulomatous or mucosal tissue; redder than surrounding skin and bleeds easily; bathed in foul, purulent discharge; indicated chronic ear disease

Romberg test

assesses ability of vestibular apparatus in inner ear to help maintain standing balance

mastoid process

bony prominence of the skull located just behind the ear

atresia

congenital absence or closure of ear canal

Eustachian tube

connects the middle ear with the nasopharynx and allows passage of air

external ear - auricle (pinna)

consists of movable cartilage and skin external auditory canal: 2.5-3 cm long in the adult and terminates at the tympanic membrane (eardrum). lined with glands that secrete cerumen

otorrhea

discharge from the ear

microtia

ears smaller than 4 cm vertically

malleus (hammer)

first of the bony ossicles that transmits and amplifies sound waves; connected to the tympanic membrane

dry cerumen

gray, flaky, and frequently forms thin mass in ear canal; occurs more often in Asians and American Indians

wet cerumen

honey brown to dark brown and moist occurs more often in Caucasians and African Americans

perforation

if the acute otitis media is not treated, the drum may rupture from increased pressure. Perforations also occur from trauma. Usually the perforation appears as a round or oval darkened area on the drum. Central perforations occur in the pars tensa. Marginal perforations occur at the annulus. Marginal perforations are called attic perforations when they occur in the superior part of the drum, then pars flaccida

cochlea

inner ear structure containing the central hearing apparatus

stapes (stirrup)

inner of the 3 ossicles of the middle ear

umbo

knob of the malleus that shows through the tympanic membrane

retracted drum

landmarks look more prominent and well defined. Malleus handle looks shorter and more horizontal than normal. Short process is very prominent. Light reflex is absent or distorted. The drum is dull and lusterless and does not move.

Incus (anvil)

middle of the 3 ossicles of the middle ear

air conduction (AC)

normal pathway of hearing, most efficient

Otitis Media (Middle Ear Infection)

occurs because of obstruction of the eustachian tube or passage of nasopharyngeal secretions into the middle ear

annulus

outer fibrous rim encircling the eardrum

keloid

overgrowth of scar tissue, which invades original site of trauma

otalgia

pain in the ear

binaural interaction

permits locating the direction of a sound in space and identifying the sound

Insertion of tympanostomy tubes

polyethylene tubes are inserted surgically into the eardrum to relieve middle ear pressure and promote drainage of chronic or recurrent middle ear infections. Tubes extrude spontaneously in 12 to 18 months

excessive cerumen

produced or is impacted because of narrow, tortuous canal or poor cleaning method.

Frostbite

reddish-blue discoloration and swelling of auricle after exposure to extreme cold

tinnitus

ringing in the ears

Organ of Corti

sensory organ for hearing

semicircular canals and vestibule

sensory organs of balance; contain receptors and endolymph that provide sensory information about the body's position to maintain equilibrium

exostosis (osteoma)

small, bony hard, rounded nodules of hypertrophic bone, covered with normal epithelium

pars flaccida

small, slack, superior section of tympanic membrane

helix

superior posterior free rim of the pinna

children's ear

the lumen is surrounded by lymphoid tissue, which increases during childhood; thus the lumen is easily occluded. this places the infant at greater risk for middle ear infections than the adult. their ear canals are shorter and have a slope opposite of an adult

pars tensa

thick, taut, central-inferior section of tympanic membrane

tympanic membrane (eardrum)

thin, translucent, oval membrane that stretches across the ear canal and separates the middle ear from the outer ear. pearly gray color and a prominent cone of light in the anteroinferior quadrant (reflection of the otoscope light). the drum is oval and slightly concave, pulled at its center by the malleus

Blue Drum (Hemotympanum)

this indicates blood in the middle ear, as in trauma resulting in skull fracture

battle sign

trauma to the side of the head may lead to a basilar skull fracture involving the temporal bone

foreign body

usually occurs in children who place a foreign body in the ear (toy, jewelry beads, cereal, corn. cotton is most common in adults, from Q-tips Also, trapped insects

ceruminolytics

wax-softening agents that expedite removal with electric or manual irrigators

cerumen

yellow waxy material that lubricates and protects the ear canal by forming a sticky barrier that helps keep foreign bodies from entering and reaching the sensitive tympanic membrane. migrates out of the meatus by movement such as chewing and talking