Audition + Vestibular

Normal TM

Perforation

Otitis Media

Otitis Externa

Scarring of TM

Attic cholesteatoma

Pinna, external auditory canal

Tympanic membrane, malleus, incus, stapes, oval window

Semicircular canals, oval window, cochlea, vestibular n, facial n, auditory n

Structures + nerves of inner ear

External Ear

Funnel sound waves to tympanic membrane via pinna and external auditory canal

Otitis Externa

Inflammation of external ear and tympanic membrane “swimmer’s ear”

Middle ear

Normally filled with air, Tympanic M vibrates and small muscles modulate vibrations

(general ear landmark)

Malleus, incus, stapes, oval window

Order of Middle Ear Bones

1. __

2. __

3. __

4. __ __

Eustachian tube

Middle ear structure connects to nasal pharynx

Pressure, equilibration

Changes to outside __ directly impact eustachian tube __

(i.e. airplane ascending)

Otitis Media

Inflammation of middle ear

Acute otitis media sx

Bulging ear drum, dull/absent light reflex

Inner Ear

For sensing movement/body position/sound perception

(general ear landmark)

Bony labyrinth, VIII, 3

Inner Ear

• Filled with fluid, encased in “__ __” 

• Innervated by CN _

• Composed of vestibular organ and cochlea

  • Cochlear with _ chambers separated by membranes

Vestibular Organ

Sensing movement and body position from inner ear

Cochlea

Perception of sound to electrical signals from inner ear via the…

Organ of corti, stiff base, flexible apex

The __ __ __ is an Inner ear structure responsible for sensing sound

• high frequencies stimulate the __, narrow __ of the cochlea (near the oval window)

• low frequencies resonate with the __, wide __ (the tip of the spiral)

Basilar Membrane

Contains hair cells and relatively flexible

Frequency, amplitude, timbre, frequency

Basilar membrane

• Vibrates according to sound __, __, and __

• Specific hair cells along organ of corti signal electrical single that correlates to specific __

tectorial membrane, fluid

Organ of corti

• Hair cell cilia either lodged in rigid __ __ OR free in the __

Sound Waves

Literal definition of changes in air compression

Frequency

Number of oscillations per second; pitch

Pitch, Hertz

Frequency

• correlated with __

• Units are in __

Volume, decibels, 100

Amplitude

• correlated with __

• Units are in __

• Over __ lead to damage

Amplitude

Height of sound wave; volume

Timbre

Quality of sound determined by specific harmonic vibrations, vibrato

Air, waves, pinna, vibrates, malleus, attenuate, oval window, electrical

Auditory transduction

1. __ is compressed

2. __ captured by the __ of ear and funneled into external auditory meatus

3. Tympanic membrane __ back and forth

4. __ (attached to tympanic M) vibrates and transmits those vibrations through incus and stapes

5. Small muscles tense and relax to __ the vibrations

6. Stapes vibrates __ __ of cochlea, causing vibrations in organ of corti

7. Organ of corti then processes vibration to become __ signals

Hair cells, cilia, first

Why do people lose their high-frequency/pitch hearing first?

• High amplitudes damage __ __ and __ (more fragile high-frequency cells)

• Organ of corti topographically experience high frequencies __ (order)

Mechanoreceptors, Ca2+, K+, cochlear, vestibulocochlear, bilaterally

Hair cells to brain

• Bending of cilia open __ that depolarize the cell (__- 2 ions)

• Signal conducted through __ nerve to __ nerve

• First order neurons synapse in brainstem and send info to temporal lobe(s) __ (uni/bilaterally)

Conductive Hearing Loss

External sound block, fluid in middle ear, fixation of middle ear bones (hearing loss)

Sensorineural Hearing Loss

Damage to inner ear, cochlea, auditory nerve going to brain (hearing loss)

Conductive, sensorineural

• In __ hearing loss, sound is adequately transmitted through bones of skull

• In __ hearing loss, sound is not adequately transmitted through bones of skull

Weber and Rinne Tests

Tests for conductive vs sensorineural hearing loss AFTER already determining the good and bad ears

AC > BC

Normal Rinne

BC > AC

Abnormal Rinne

Conductive, bad, sensorineural, good

Weber Test

• In __ loss - BC > AC for bad ear; lateralizes to the __ ear

• In __ loss - AC > BC for both ears; lateralizes to the __ ear

Speech, behavioral, dementia, social

Manifestations of Hearing Loss

• Children - Present with delayed __, __ problems, inattentive, ignoring

• Elderly - Present like __, __ withdrawal

Vestibular Organ

Senses equilibrium and balance via movement of head

Cerebellum, brainstem, extraocular

Vestibular organ

• Coordinates with the __ and __ (brain regions) medial motor tracts for balance

• Coordinates with the __ muscles to maintain a stable visual field

Angular, linear

The Semicircular Canals are for __ acceleration

Whereas the Otolith Organs are for __ acceleration

Rotation, tilt, delayed, fixed, normal, rotation, lags, opposite, fall, electrical

Angular Acceleration

1. Sense head __ and __ (front to back and side to side)

2. As head is turned, fluid in canal is slightly __ and pushes against __ hair cells

3. Eventually fluid starts to move as well “catches us” → Results in hair cells to return to __ position even though __ may still happen

4. When rotation stops, fluid __ behind and bends hairs in __ direction

• Makes us perceive spinning in opposite direction and sometimes __

5. Info is then converted from __ info about movement

Utricle, saccule, linear

Otolith organs

• __ and __ contain gelatinous layer embedded with otoliths (crystals)

• Movement (particularly __ acceleration) moves otolith mass and bends the hairs

Benign Paroxysmal Positional Vertigo (BPPV)

Calcium carbonate debris within semicircular canals leads to inappropriate bending of hair cells with movement, signaling spinning

Angular, semicircular canal, posterior

• Vertigo with spinning relates to __ circulation

  • __ __ pathology

• BPPV usually affects the __ canal

Dix-Hallpike Maneuver

Reproducible vertigo and nystagmus when head tilted toward dysfunction side to dx BPPV

Eply Maneuver

Therapeutic rotation of head in different planes to move crystals out back to correct site

posterior vertigo, antihistamines

Eply Maneuver

• Only 2% of patients require more than 3 treatments for __ __ (vertigo type)

• __ (i.e. meclizine, diphenhydramine) help with sx after this maneuver