EARS

• Functionof ear

  Hearing; sustaining equilibrium
• Ear


  • Three distinct portions
• External ear development


  1. Starts at sixth week of gestation

  2. Includes external auditory canal, tympanic membrane
• Cerumen


  Ear wax
• Middle ear


  • Dampens volume
  • Has four openings
  • Contains bones: malleus, incus, and stapes
  • Openings: tympanic membrane, cochlear window: oval window, eustachian tube
• Anatomy of the ear

  • Helix
  • Antihelix
  • Concha
  • Antitragus
  • Tragus
  • Lobule
• Middle ear


  • Begins at the medial or inner side of the eardrum
  • Separated from external ear by the eardrum
  • Contains the epitympanum with the eustachian tube opening and the three ossicles: malleus, incus, and stapes
• Eardrum


  • Transparent, opaque, or pearly gray
  • Moves when air is infected into the external canal
  • Landmarks: annulus, pars flaccida, pars tensa
  • Attached to the malleus at the umbo
• Middle ear


  • Separated from inner ear by the round window and the oval window
  • Eustachian tube begins at the floor and extends to the throat
• Inner ear


  • Responsible for sound translation to cranial nerve (CN) VIII
  • Responsible for vestibular function
  • Maintained in semicircular canals, vestibule
  • Bony labyrinth with semicircular canals, vestibule, cochlea
• Semicircular canals


  • Tubes made of cartilage containing fluid and hair cells
  • Connected to vestibular portion of 8th cranial nerve
  • Help maintain sense of balance
• Cochlea


  • Spiral organ of hearing
  • Divided into scala tympani and scala vestibuli
  • Filled with endolymph and perilymph to protect and cushion
  • Contains organ of Corti with hair cells that detect vibration and stimulate 8th cranial nerve
• Vestibule


  • Small, oval-shaped, bony chamber between semicircular canals and cochlea
  • Contains utricle and saccule, important for balance
• Amplitude (volume)


  • Change of atmospheric pressure against tympanic membrane = intensity of sound
  • Measured in decibels
• Frequency (pitch)


  • Sound waves
  • Measured in Hertz
• Normal conversation: 10 to 60 dB and 200 to 5,000 Hz
• Sound perception


  Air conduction, bone conduction
• Voice, whisper, and balance test

  1. Test hearing acuity: Observe behavioral response to conversational speech

  2. Voice test: Whisper two-syllable words, patient repeats

  3. Romberg test: Stand with feet together, eyes closed, maintain balance for 20 seconds
• Auditory acuity testing


  1. Test each ear independently

  2. Finger rub test: Patient indicates when they hear it

  3. Whisper test: Patient repeats whispered numbers/letters
• Bone conduction testing


  1. Use oscillator to send pure tones to inner ear

  2. Patient signals when they hear a sound
• Tuning fork tests


  1. Weber test: Vibrating tuning fork on midline, patient indicates if sound is equal bilaterally

  2. Rinne test: Vibrating tuning fork near ear canal, patient indicates when sound can no longer be heard
• Normal tuning fork test findings

  • Weber test: Able to hear sound equally in both ears
  • Rinne test: Air conduction > bone conduction
• Sensorineural hearing loss


  • Gradual damage to hair cells in cochlea
  • Causes: Excessive noise, diseases, ototoxic drugs, genetic, maternal rubella
• Conductive hearing loss


  • Inability to effectively transfer sound between outer, middle, and inner ear
  • Causes: Ear wax, infections, perforated eardrum, otosclerosis
• Sensorineural hearing loss


  • Dysfunction of cochlea and/or vestibulocochlear nerve
  • Causes: Age, noise, genetics, infections, ototoxic agents
• Vestibular function evaluation


  1. Romberg test: Maintain balance with feet together, eyes open then closed

  2. Normal: No stepping or widening base

  3. Abnormal: Stepping or widening base
• Rinne tuning fork test

  1. Place tuning fork on mastoid bone, then 1 cm from ear

  2. Normal: Louder 1 cm from ear (positive Rinne)

  3. Abnormal: Louder on mastoid (conductive hearing loss)
• Abnormal ear findings


  • Otalgia (earache)
  • Otorrhea (ear discharge)
  • Presbycusis (age-related hearing loss)
  • Tinnitus (ringing in ears)
  • Vertigo (room spinning)
  • Microtia (small ears)
  • Macrotia (large ears)
  • Impacted cerumen
  • Otitis media (middle ear infection)
  • Otitis externa (outer ear infection)