Ears

External auditory canal

Functions to let sound waves in

S-shaped, 2.5-3 cm long

Terminated at the tympanic membrane (TM)

Cerumen

Ear wax; purpose is to protect and lubricate the ear

Malleus

A small bone in the middle of the ear which transmits vibrations of the eardrum to the incus

Umbo

The central point of maximum depression on the TM, formed by the distal end of the malleus bone’s handle (manubrium)

Manubrium

Handle

Attached to the medial surface of the TM and it pulls its anterior an inferior portion medially giving it a conical shape

Anterior short process

Also known as processus gracilis

A finger-like projection of the malleus that extends forward to the petrotympanic fissure and is held in place by ligaments

Works with the incus and stapes bones to transmit sound vibrations to the inner ear

Middle ear

Tiny air-filled cavity

Contains the auditory ossicles, the malleus, incus, and staples

Openings into the middle ear

Oval window, round window, eustachian tube

Eustachian tube

Connects the middle ear with the nasopharynx

Usually closed, but opens with swallowing and yawning

Three functions of the middle ear

Conducts sound vibrations from the outer ear to the central hearing apparatus in the inner ear

Protects the inner ear by reducing the amplitude of loud sounds

Eustachian tube: Allows equalization of air pressure on each side of the TM (prevents rupture)

The body labyrinth of the inner ear

Sensory organs for equilibrium and hearing

Vestibular apparatus 

Vestibule

Semicircular canals 

Cochlea (central hearing apparatus)

Peripheral

The ear transmits sound and converts vibrations into electrical impulses to be analyzed by the brain

The organ of Corti

Sensory organ of hearing

What cranial nerve is responsible for conducting nerve impulses to the brain to the organ of corti?

CN III

CN VIII

Vestibulocochlear nerve

Brainstem

Permit the location of sound in space through binaural interaction and identifies the sound

Cerebral cortex

Interprets the meaning of sound and begins the appropriate response

Air conduction (AC)

Normal pathway/most efficient; relies on sound traveling through the ear canal

Bone conduction (BC)

The bones of the skull vibrate, and the vibrations are transmitted directly to the inner ear and CN VIII

Conductive loss

Involves dysfunction of the external or middle ear

A partial loss if amplitude is increased enough, the person will hear that sound 

Etiology of conductive loss

Impacted cerumen?

Foreign body?

Perforated TM?

Pus or serum in the middle ear?

Otosclerosis?

Sensorineural loss

Perceptive

Involves pathology of the inner ear, CN VIII, or the auditory areas of the cerebral cortex

Presbycusis

Gradual nerve degenerations the occurs with aging, and ototoxic drugs

Otosclerosis

Abnormal bone growth that impedes vibration

Equilibrium

Labyrinth in the inner ear continuously provides information to the brain about the body’s position in space

What happens if the labyrinth becomes inflamed?

The messages sent are incorrect and can result in staggering gait and vertigo 

Developmental considerations: Presbycusis

Type of hearing loss that occurs with aging, even in people living in quiet environment

Gradual sensorineural loss caused by nerve degeneration of ear or auditory ear

Documented in 2/3 of the population over age 70

First notice of high-frequency tone loss

Ability to localize sound is impaired 

Infants: Eustachian tube

Shorter, wider and more horizontal than the adult’s

Infants: EAC

Shorter and has an opposite slope compared to the adult

How would you tug the ear in an adult when examining it?

Pull the auricle up and back

How would you tug the ear in children when examining it?

Pull the auricle down and back

Dry cerumen 

Gray, flaky, and frequently forms a thin mass in the EAC

Wet cerumen

Honey brown to dark colored and moist

Otitus media (OM)

High incidence among Native Americans, Alaskan, and Canadian Natives

Down syndrome

Premature syndrome

Premature infants

Infants bottle-fed in supine position

Persistence of middle ear effusion after tx

Subjective data: Ear

Otalgia- Ear pain 

Infections, discharge (external otitis), hearing loss, environmental noise, tinnitus, vertigo, self-care behaviors

For infants and children: When, what first infection? Secondhand smoke? Daycare? Bottle fed?

Perforated eardrum s & symptoms

Ear pain

Discharge (clear, yellow, or bloody)

Objective assessment: Ear

External ear: Size and shape

Skin condition

Tenderness

EAC

Objective data: Ear

Otoscopic exam 

Purulent otorrhea (ear drainage) in the EAC

Frank blood or CSF? 

TM- Color? Position? Integrity? 

Whisper test

Whisper=High frequency

Have patient cover one ear. In the other ear (5-6 feet away) whisper three random words. The patient should be able to repeat them correctly. Repeat on both ears

Weber test

Sound lateralized to one ear with a conductive or sensorineural loss

Tuning fork on the top of the head and patient says whether the sound is equal in both ears

Rinne test 

A positive Rinne=a normal test result (AC>BC)

Activate tuning fork, then place on mastoid process and instruct patient to alert screener when they stop hearing the sound (screener is counting how many seconds it took). Screener then moves fork in front of EAC and instructs the patient to say when they stop hearing the sound (again counting how long this takes). 

Healthy ear

TM should appear pearly gray and slightly concave