Hearing and Balance

Question 1

What muscle pulls the handle of the malleus that is attached on the tympanic membrane?

Answer 1

Tensor tympani

Question 2

The subsequent movement of the ____ and the movement of the fluid will be converted to signals which will be sent to the CNS.

Answer 2

stapes

Question 3

The force generated by the tympanic membrane as well as the malleus and incus will provide what is called ________ that will allow stapes to transmit vibration to the inner ear

Answer 3

Impedence matching

Question 4

A system of coiled structure in the inner ear that is enclosed in a bony matrix

Answer 4

Cochlea

Question 5

Number of coils of the cochlea

Answer 5

2 and 1/2 turns

Question 6

The cochlea coils around what bone?

Answer 6

modiolus

Question 7

Fluid contained in the scalae tympani and vestibuli

Answer 7

Perilymph

Question 8

Fluid within scala media

Answer 8

endolymph

Question 9

Separation of the scala media and scala vestibuli that has minimal role in sound conduction

Answer 9

Reissner’s membrane

Question 10

Part of the inner ear responsible for conduction of sound from external ear to the Organ of Corti

Answer 10

Cochlea

Question 11

This converts sound waves to electrical signals

Answer 11

Organ of Corti

Question 12

Fibrous membrane separating scala media and tympani

Answer 12

Basilar membrane

Question 13

True or False:

The stapes region of the basilar membrane has longer basilar fibers

Answer 13

False:
▪ Stapes - base (short fibers) (wider in diameter)
▪ Helicotrema - apex (longer fibers) (narrower in diameter) (12x longer than the base or oval window)

Question 14

True/False:

The helicotrema has basilar fibers that have narrower diameter

Answer 14

True:
▪ Stapes - base (short fibers) (wider in diameter)
▪ Helicotrema - apex (longer fibers) (narrower in diameter) (12x longer than the base or oval window)

Question 15

True or false:

The apex of the cochlea has longer basilar fibers

Answer 15

True:
▪ Stapes - base (short fibers) (wider in diameter)
▪ Helicotrema - apex (longer fibers) (narrower in diameter) (12x longer than the base or oval window)

Question 16

Which part of the basilar membrane has a natural resonance to high frequency sound waves?

Answer 16

Base

Question 17

Area where sounds of different frequencies are detected and converted to nervous signals

Answer 17

Organ of Corti

Question 18

Which part of the basilar membrane has a natural resonance to low frequency sound waves?

Answer 18

Apex

Question 19

The actual sensory receptors within the Organ of Corti

Answer 19

Hair cells

Question 20

Outer hair cell occurs in how many rows near the saccule?

Answer 20

3 rows

Question 21

Outer hair cell occurs in how many rows near the apex?

Answer 21

5 rows

Question 22

What controls the sensitivity of the inner hair cells by passing to the outer hair cells?

Answer 22

Retrograde nerve fibers from the brainstem

Question 23

Inner hair cell occurs in how many rows?

Answer 23

Single row only

Question 24

To which ganglia do the short cilia of the inner hair cells synapse?

Answer 24

Spiral ganglion and cochlear ganglion (95% of nerve endings in this ganglia synapse with inner hair cells)

Question 25

Bending of which structure of the hair cells excites the auditory nerves?

Answer 25

Stereocilia which either touch or are embedded in the surface gel coating of the tectorial membrane

Question 26

A rigid, flat plate where the outer ends of the hair cells are tightly fixed

Answer 26

Reticular lamina

Question 27

Structures that are attached tightly to the basilar fibers and support the reticular lamina

Answer 27

Rods of Corti

Question 28

What secretes the endolymph contained by the scala media?

Answer 28

Stria vascularis

Question 29

Which ions are of high and low concentration in the endolymph, respectively?

Answer 29

High K+

Low Na+

Question 30

The perilymph within the scala vestibuli and scala tympani is almost identical to which ECF?

Answer 30

CSF due to their direct communication with the subarachnoid space

Question 31

Hair cells at the endolymph have a negative intracellular potential of ___ millivolts with respect to the perilymph

Answer 31

−70 mV

Question 32

Hair cells at the perilymph have a negative intracellular potential of ___ millivolts with respect to the endolymph

Answer 32

-150mV

Question 33

The possible rapidly acting neurotransmitter release by hair cells at their synapses causing depolarization:

Answer 33

Glutamate

Question 34

Sequence of Hair cell receptor excitation:

Answer 34

Bending of basilar fibers upwards (towards the scala
vestibuli) >
Bending of stereocilia towards the kinocilium
stereocilia towards the kinocilium (away
from the modiolus) >
Opening Opening of 200 to 300 cation cation-conducting (K+) channels >
Rapid movement of K+ ions from the surrounding scala media fluid into the stereocilia >
Depolarization of the hair cell membrane >
Opening of Ca2+ channels >
Influx of Ca2+ >
Release of vesicles containing neurotransmitter (glutamate) at the base of the hair cells >
Stimulation of the cochlear nerve ending

Question 35

Sound localization is more precise discriminating:

direction or intensity?

Answer 35

Direction than detecting intensities as it does not depend on external factors and is only concerned with time.

Question 36

Specific nuclei responsible for detecting time lag of sound entering the ears.

Answer 36

Medial Superior Olivary nucleus

Question 37

Specific nucleus responsible for detecting direction of sounds by comparing the intensities of the sounds reaching the ears.

Answer 37

Lateral Superior Olivary Nucleus

Question 38

Sound waves cause basilar fibers from the base of cochlea to move towards which window of the ear?

Answer 38

Round window