Hearing and Balance

Outer, middle

What part of the ear conduct vibrations in the air to sensory structures?

pitch

Characteristic of sound determined by wavelength (frequency)

loudness

Characteristic of sound determined by amplitude?

lower pitch

Longer sound waves would result in a:

louder sound

Taller sound waves would result in:

dB

Measurement of loudness

0 dB

What is the limit of hearing?

0-20kHz

Human Hearing Range

Outer ear

Funnels the vibration in the air to vibrate the tympanic membrane

auricle, external auditory canal, tympanic membrane

Parts of the outer ear

Auricle

Fleshy outer ear made of cartilage and a unique funnel shape.

external auditory canal

Outer ear piece lined with guard hairs and cerumen to make the hairs sticky

tympanic membrane

Outer ear piece vibrated by sound

5, 7, 9, 10

What nerve innervate the tympanic membrane

Tympanic cavity

The middle ear structure extending from the tympanic membrane

inner ear

The oval window represents the:

Ossicles

What transmits the vibrations from the tympanic membrane (outer ear) to the oval window (inner ear)

equalize pressure

What is the purpose for air passages in the middle ear, like the auditory tube?

auditory/eustachian

What air passage in the middle ear connects to the nasopharynx?

auditory tube

In babies, this tube is shorter and more horizontal, increasing the risk of ear infections

decreases

The surface area __________ from the tympanic membrane to the oval window.

ossicles (malleus, incus, stapes)

3 bones of the middle ear

amplify, dampen

The middle ear can ________ and _____________ intensity of sound

pressure

the oval window has a lower area, and therefore a larger ____________

mechanical advantage

The malleus acts as a lever, giving a greater ____________________ for transmitting the force applied to the ear

pressure

The middle ear must increase the ______________ in the ear in order to convert vibrations in the air to vibrations in the ear fluid and increase intensity

tensor tympani, malleus

What muscle is controlled by the trigeminal nerve (CN 5) and contracts to dampen vibrations in the tympanic membrane and decrease sound intensity? What bone is this muscle attached to?

stapedius, stapes

What muscle is controlled by the facial nerve (CN 7) and contracts to dampen vibrations in the oval window and decrease sound intensity? What bone is this muscle attached to?

Auditory

This reflex is triggered by loud sounds or vocalizations

Bony labyrinth

Hard outer covering of inner ear

perilymph

coming after the bony labyrinth, this portion of the inner ear is termed "extracellular fluid" because it is low in potassium.

membranous labyrinth

Site of the "magic" in the ear; where all the work happens, like signal transduction

endolymph

Inner portion of the inner ear, termed "intracellular fluid" because it is high in K+

Cochlea, vestibule, semicircular canals

What are the 3 inner ear divisions?

perilymph, endolymph, hair cells, CN8 communication

What are the common features among all three inner ear divisions?

Cochlea

What inner ear division is responsible for sound?

vestibule

What inner ear division is responsible for head position?

semicircular canals

What inner ear division is responsible for rotation ?

0

What is the net pressure produced in the cochlea due to the oval and round windows?

Organ of Corti

Center part of the cochlea, containing hair cells, canals, and membranes; auditory sense organ in scala media

Basilar membrane

Vibrations of what structure in the organ of corti move the hair cells?

inner, outer

Types of hair cells

Inner

Which hair cells are most responsible for sound transduction?

sound amplification

what is the main function of the outer hair cells?

attached to tectorial membrane

What is important to remember about the outer hair cells in the organ of corti?

tectorial membrane

When the basilar membrane vibrates, what structure is it pushed in to?

stereocilia

small hairlike projections on the tops of inner and outer hair cells

endolymph

What anatomical region of the inner ear are stereocilia located?

tip links

Structures at the tops of the cilia of auditory hair cells, which stretch or slacken as the cilia move, causing ion channels to open or close.

K+ flows in, depolarization

If stereocilia are physically pulled open, what happens?

CN 8

Stereocilia opening would cause an increase in which nerve?

perilymph

What anatomical region of the inner ear are cell bodies located?

cell body

what part of the hair cell communicated with CN8?

Ca2+ channels opening

When transducing sound, the mechanically gated ion channels opening, which also stimulate what other channel and action?

neurotransmitter release, opens Ca2+ gated K+ channels

What is calcium responsible for in transduction?

False (both passively)

In transduction, potassium is able to enter the cell passively and leave the cell actively. True or false?

location, firing rate

What two characteristics of the neuron does the frequency coding of sound depend on?

apex

Cochlear fibers of the basilar membrane are wider near the base or apex?

low

Wider basilar fibers at the apex would produce ________ frequency sounds compared to thinner thinner fibers at the base

hair cells

CN8 is stimulated when _______ __________ depolarize

place

location of the cochlear fibers (what part of the cochlea is active) would be the _________ code.

frequency

How rapidly the CN8 nerve is firing would be the ______________ code

pitch

Frequency code and place code determine what characteristic of sound?

tectorial

OHC attachment to the ___________ ______________ amplifies vibrations

depolarize

When the OHCs push up (pushing the smaller one to the taller one), does it depolarize or repolarize?

True

When the OHC hyperpolarize they are lengthening. True or false?

basilar membrane

OHCs amplify sound by moving the __________________ up and down.

superior olivary nucleus

Reflex to control loud sound amplification comes from the:

False? (Hyperpolarize)

The superior olivary nucleus inhibits the OHCs by depolarizing them and making them longer. True or False?

excitatory

The superior olivary nucleus has excitatory or inhibitory effects?

tectorial and basilar membrane

The superior olivary nucleus increases the distance between what two structures?

85

Sounds greater than _________ dB can cause damage to your hearing

tinnitus

Hair cell damage from excessive loudness causes ___________

outer, middle

Conduction deafness involves impairments in what sections of the ear?

external hearing aids

Amplify vibrations for conductive deafness

sensorineural deafness

Hearing loss involving hair cell loss

cochlear implants

Treatment for sensorineural deafness

spinal ganglion cells

primary afferent in auditory pathway

cochlear nuclei

secondary afferent in auditory pathway

inferior colliculus

3º afferent in auditory pathway

medial geniculate

4º afferent in auditory pathway

auditory pathway

Which pathway has an extra, fourth, neuron?

superior temporal lobe

Where is the sensory cortex information released in the brain?

superior olive

What can help with sound localization, but is technically not a part of the auditory pathway

Tonotopic maps

Maps in the brain that help us determine what a sound is by reading the pitch; every nucleus has one

Left superior olivary nucleus

when sound occurs on the left side of the body, what structure localizes sound by inhibiting the right side?

volume

Lateral sound localization from the SON is all based on the _____________ of sound

timing

Medial sound localization (sound between the left and right SONs) is based on the ______________ of sound

Mastoid cells

Structures in the middle ear that function as a buffer for air pressure

Vestibule

Senses head orientation and linear accelerations

otoconia

tiny calcium carbonate stones in the ear that provide inertial mass for the otolith organs, enabling them to sense gravity and linear acceleration

otolithic membrane

gelatinous layer located directly over hair cells in the vestibule

gravity, linear head displacement

the vestibule relies on what two things to sense head orientation and linear acceleration

maculae

oval structures in the vestibule where hair cells cluster

stereocilia

Maculae contain ___________ in the otolithic membrane

gravity

___________ pulls the otoconia in the maculae down so that the kinocilium (tallest stereocilia) goes toward the striola

utricle, saccula

Types of maculae

utricule

Horizontal macula, most sensitive when upright

saccula

Vertical macula, most sensitive while in supine

kinocilia

What is the tallest stereocilla in the macculae called?