Middle Ear

Where does the Oval window enter to?

Cochlea

What does the stapes footplate connect to?

Oval window

Where is the ossicle transferring sound energy?

From the air-filled external auditory canal to the fluid- filled inner ear.

What connects to the tympanic membrane?

ossicles (the 3 bones)

_____ embedded in fibrous layer of TM

A) Incus B) Manubrium (malleus)

Manubrium (malleus)

What is attach to the TM through the manubrium?

A.Stapes

B.Malleus

C.Incus

b. Malleus

What is connected to the malleus?

A.Stapes

B.Malleus

C.Incus

C. Incus

What is connected to the incus?

stapes

Why is footplate important?

contacts oval window of cochlea

Name the non-auditory structure at the middle ear

Stapedius muscle, tensonr tympani muscle, eustachian tube , cranial nerve VII (facial nerve) and bloody supply, portions of CN IX (Glossopharyngeal nerve)

stapedius is part of what?

A. Incus

B. Malleus

C. Stapes

C. stapes

tympani is is part of what?

A. Incus

B. Malleus

C. Stapes

B. malleus

what is the purpose of tympani?

to drecrase sound transmission

Where is stapedius and tensor tympani muscles located at?

Middle Ear or Inner Ear

Middle ear

Eustachian Tube (ET) (power point definition)

maintaining equal pressure between the ear canal & middle ear space

In the eustachian tube why is it important for pressure be equal on both side of the tympanic membrane?

to maximize it’s mobility for the passage of sound. Called __pressure equalization.__

what is the tympanic membrane connect to?

Manubrium

the eustachian tube passes down to?

ear canal and middle ear space.

When does the ET open( how to remove it)?

yawning, sneezing, swallowing or when excessive air pressure is applied from the nose.

T/ F Does the ET open about once per minute while awake and once every 5 minutes while asleep?

True

Name the two structures of the tympanic cavity after elevation of the tympano-metal flap.

Facial Nerver and Internal Carotid Artery

Name the Prussak space & the surrounding ligamental folds of the malleus.

Chorda tympani

what does the facial nerve lead to?

trauma

Define ET

are the reason when your ear pop on airplane and in elevator. feeling comes from when theres a build up of pressure in the middle ear.

What is the main role of the middle ear?

serves as an impedance matcher

when sound travels from the outer ear to the inner ear, it must transition from what?

Air to fluid without losing energy

What is the problem about impedance maismatch?

__**Fluid has a much higher**__ impedance __than air__

Impedance

opposition to energy flow; influenced by mass, stiffness, and frictional resistance of the system

the anatomical structure of the middle ear ______ the force of sound wave so that energy is NOT lost when the __sound travels from air to fluid__

A) increases B) decreases

increases

why does the middle ear increase the force sound wave

so, we don’t lose sound

what happens with out the ossicle?

__*air to fluid impedance mismatch*__ between the outer ear & inner ear would result in a __**28 dB loss of sound pressure.**__

What are the two ways that the middle ear compensate for loss of sound pressure?

area ratio and lever action

Is the tympanic membrane much larger than the oval window? yes/no

yes

Area Ratio Mechanism

energy increases because the energy from larger tympanic membrane onto a smaller oval window, which increases sound.

Through leverage, the force received at the _____ footplate is greater than that applied at the malleus

A) Stapes B) incus

A) stapes

the mass of the ossicular chain is poised to take advantage of the?

physical laws of leverage

lever increases pressure at the ____ arm (incus)

A) long B) short

B) short

in the physical laws of leverage the ratio of tympanic membrane displacement to oval window displacement is increased by about ___

1\.3:1

in the lever action mechanism what happens?

the ossicles rock back & forth on an axis and the action of the stapes in the oval window is like that of a pivot

What is our primary tool for assessing middle ear health?

Immittance

Immittance test

measure how successfully energy is transferred through the middle ear

What are the two primary components to immittance testing?

Tympanometry and acoustic reflex testing

tympanometry (immittance bridge)

measures __**middle ear pressure**__ by determining the flexibility of the tympanic membrane in response to various amounts of __positive & negative__ __air pressure__ sent through the ear canal

Acoustic reflex testing

measures __**contraction of the middle ear**__ muscles in response to loud sounds, which has the effect

What are the three small tubes attached to a metal probe, which is fitted into the ear canal with an airtight seal?

miniature loudspeaker, tiny microphone and air pressure pump.

miniature loudspeaker

presents a pure tone to the ear typically 226 Hz (low frequency)

tiny microphone

measures the intensity of the tone as it is reflected from the tympanic membrane

air pressure pump

can vary the pressure within the ear canal (creates either positive or negative pressure)

Immittance measures are based on principles what are they?

* when any sound wave is delivered to the ear, some energy is transferred through the __middle ear,__ reaches the __inner ear__ and is perceived as sound.
* some of the sound energy is reflected back out from the tympanic membrane
* the amount of reflected energy will vary depending on the __impedance__ of the system

___ is the dominant factor that determines __**how much sound reaches the inner ear**__ and how much is reflected __back out__

stiffness

when the system ( outer ear & middle ear structures) are stiffer (less compliant/less mobile), ___ energy will be reflected

A) more B) less

more

when the system is __**less stiff**__ (more compliant/more mobile), ___ energy will be transmitted to inner ear ( less energy is reflected back out)

A) more B) less

more

What determines the point and magnitude of greatest compliance/flexility of the tympanic membrane?

tympanometry

Tympanometry

* A 226 Hz probe tone is presented, and the tympanic membrane is loaded with ____ daPa of pressure.
* then, tympanic membrane is measured successively as the pressure in the ear canal is ___
* after the pressures reaches __daPa _ (atmospheric pressure), the pump creates __**negative pressure**__, and additional tympanic membrane compliance measurements are made

\+200 daPa

decrease

0 daPa

in a healthy ear, the tympanic membrane is most compliant/flexible near the ____?

atmospheric pressure (0daPa)

an unhealthy ear has __

a-lot of fluid

what are the two tympanogram types that have a normal peak?

* Type A, Ad

type A

normal middle ear pressure/ Tm mobility

type Ad

normal middle ear pressure, overly mobile TM

type As

normal middle ear pressure, less mobile TM than avergare

type B

Flat, __no TM mobility__; middle ear pressure cannot be ascertained

type C

negative middle ear pressure ; normal TM mobility

Which tympanogram type indicates that no TM mobility was measured?

A) type C

B) type B

C) type As

D) type A

type BIn a healthy ear, the TM is most compliant near atmospheric pressure

In a healthy ear, the TM is most compliant near atmospheric pressure. True/False

true

The eustachian tube is positioned more horizontally in children than it is in adults. True/false

true

What type of tympanogram has no peak?

A) Type As

B) Type C

C) Type B

D Type Ad

E) Type A

\

type b

What type of tympanogram has peak?

A) Type As

B) Type C

C) Type B

D Type Ad

E) Type A

type As, type c, type Ad, type A

Ear canal __**Volume**__ (ECV)

volume of the ear canal, usually in mL

Peds: 0.3 to 0.9

Adults: 0.9 to 2.0

peak pressure (in daPa)

the pressure at which maximum TM flexibility/compliance occurs

* 50 to -200 daPa (for kid & adult)

compliance (in mL)

the “height” at the point of maximal TM flexibility/compliance

Peds: 0.25 to 1.05

Adults: 0.30 to 1.70

tympanometric width (TW)

the interval between the 50% most __positive__ & the 50% most __negative__ point of the peak height

Peds: 80 to 159 daPa

Adults: 51 to 114 daPa

Disorders of the middle ear

abnormalities of the middle ear can led to _____ (air bone gaps > 10 dB)

A) Conductive

B) Sensorineural

conductive

Name the disorders of the middle ear

Negative middle ear pressure (infection)

Eustachian tube dysfunction

Ottis media

Cholesteatoma

Facial palsy

Otosclerosis

Negative middle ear pressure

unequal air pressure- the eardrum is bulging inward, the eustachian tube is blocked which means is not opening properly

Negative middle ear pressure can lead to a ____

retracted TM (draw back)

What are the common causes of ETD?

\

* Edema (swelling) of the ET secondary to infection or allergy
* Blockage of the ET opening by hypertrophied (overgrown) adenoids
* Structural abnormalities in the mechanism involved in opening the ET

Negative middle ear pressure

__air trapped__ within the __middle ear__ becomes absorbed by the middle ear tissue without normal replenishment through the eustachian tube

what type of typanometry is eustachian tube dysfunction (ETD)?

A) Type As

B) Type C

C) Type B

D Type Ad

E) Type A

type c

tympanic membrane retraction

can interfere with the __normal vibration of the tympanic membrane__ and may produce a slight conductive hearing loss

what is the purpose of Pressure equalizing tubes?

to equalize pressure

Otitis media

infection of the mucous membrane lining of the middle ear space

what does the serous otitis media (otitis media with effusion) include?

A) fluid in the middle ear

B) fluid build-up in the middle ear with pus formation; purulent (pus-producing) organism

fluid in the middle ear

what is the suppurative otitis media?

A) fluid in the middle ear

B) fluid build-up in the middle ear with pus formation; purulent (pus-producing) organism

fluid build-up in the middle ear with pus formation; purulent (pus-producing) organism

what type of typanometric is otitis media?

A) Type As

B) Type C

C) Type B

D Type Ad

E) Type A

type B (flat)

what is the audiometric findings of otitis media?

A) mixed

B) conductive

C) Sensorineural

conductive

what are some of the risk factor of otitis media?

eustachian tube dysfunction (ETD), barotrauma, anatomical deformities of middle ear structures, age, immune system integrity, __exposure to tobacco smoke,__ winter season and socioeconomic status

____ is seen in nearly 70% of children born in the US before age 2 years, with >50% of them experiencing multiple episodes

A) cholesteatoma

B) otitis media

Otitis media

Name the treatments for middle ear fluid and otitis media

Wait and see approach, Myringotomy, PE tube, Antibiotics

Treatment for middle ear fluid and otitis media: wait and see approach

\~ 90 of ear infections resolve on their own in 90 days

Treatment for middle ear fluid and otitis media: Myringotomy

incision into the tympanic membrane to relieve pressure and suction out remaining fluid

Treatment for middle ear fluid and otitis media: PE tube

a small tube is inserted through the myringotomy to keep the middle ear patent and allow ventilation (artificial ET) (maintain equal pressure)

Treatment for middle ear fluid and otitis media: Antibiotics

Important to avoid over use and development antibiotics resistant bacteria.

\~ American Academy of Pediatrics recommends limiting use to children with severe infection. (significant pain or fever of >= 102.2 degrees F or whose infection persist for 72 hours)

Is Cholestestoma a cancer tumor?

True/False

False

Cholesteatoma

A pseudotumor that forms from __**keratin**__ (an insoluble protein) mixed with squamous epithelium (skin) and fats (cholesterol)

Can __form when skin enters the middle ear space__.

__Highly erosive__; can cause destruction of bone and other tissue

how can cholesteatoma be treated?

through surgery

Otosclerosis

Formation of new growth of spongy bone, usually over the stapedial __**footplate**__ of one or both ears. The footplate becomes partially fixed in the oval window, __**stiffening the ossicular chain.**__

Which disorder is common of hearing loss in __adults__ that is often hereditary (70% of cases)?

A) Negative middle ear pressure (infection)

B) Eustachian tube dysfunction

C) Ottis media

D)Cholesteatoma

E) Facial palsy

F) Otosclerosis

Otosclerosis

which disorder is observed in Caucasians and twice as common in women as in men?

A) Negative middle ear pressure (infection)

B) Eustachian tube dysfunction

C) Ottis media

D)Cholesteatoma

E) Facial palsy

F) Otosclerosis

Otosclerosis

which disorder is common in children?

A) Negative middle ear pressure (infection)

B) Eustachian tube dysfunction

C) Ottis media

D)Cholesteatoma

E) Facial palsy

F) Otosclerosis

Ottis media and Eustachian tube dysfunction