Hearing and Balance Flashcards
What muscle pulls the handle of the malleus that is attached on the tympanic membrane?
Tensor tympani
The subsequent movement of the ____ and the movement of the fluid will be converted to signals which will be sent to the CNS.
stapes
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
Impedence matching
A system of coiled structure in the inner ear that is enclosed in a bony matrix
Cochlea
Number of coils of the cochlea
2 and 1/2 turns
The cochlea coils around what bone?
modiolus
Fluid contained in the scalae tympani and vestibuli
Perilymph
Fluid within scala media
endolymph
Separation of the scala media and scala vestibuli that has minimal role in sound conduction
Reissner’s membrane
Part of the inner ear responsible for conduction of sound from external ear to the Organ of Corti
Cochlea
This converts sound waves to electrical signals
Organ of Corti
Fibrous membrane separating scala media and tympani
Basilar membrane
True or False:
The stapes region of the basilar membrane has longer basilar fibers
False:
▪ Stapes - base (short fibers) (wider in diameter)
▪ Helicotrema - apex (longer fibers) (narrower in diameter) (12x longer than the base or oval window)
True/False:
The helicotrema has basilar fibers that have narrower diameter
True:
▪ Stapes - base (short fibers) (wider in diameter)
▪ Helicotrema - apex (longer fibers) (narrower in diameter) (12x longer than the base or oval window)
True or false:
The apex of the cochlea has longer basilar fibers
True:
▪ Stapes - base (short fibers) (wider in diameter)
▪ Helicotrema - apex (longer fibers) (narrower in diameter) (12x longer than the base or oval window)
Which part of the basilar membrane has a natural resonance to high frequency sound waves?
Base
Area where sounds of different frequencies are detected and converted to nervous signals
Organ of Corti
Which part of the basilar membrane has a natural resonance to low frequency sound waves?
Apex
The actual sensory receptors within the Organ of Corti
Hair cells
Outer hair cell occurs in how many rows near the saccule?
3 rows
Outer hair cell occurs in how many rows near the apex?
5 rows
What controls the sensitivity of the inner hair cells by passing to the outer hair cells?
Retrograde nerve fibers from the brainstem
Inner hair cell occurs in how many rows?
Single row only
To which ganglia do the short cilia of the inner hair cells synapse?
Spiral ganglion and cochlear ganglion (95% of nerve endings in this ganglia synapse with inner hair cells)
Bending of which structure of the hair cells excites the auditory nerves?
Stereocilia which either touch or are embedded in the surface gel coating of the tectorial membrane
A rigid, flat plate where the outer ends of the hair cells are tightly fixed
Reticular lamina
Structures that are attached tightly to the basilar fibers and support the reticular lamina
Rods of Corti
What secretes the endolymph contained by the scala media?
Stria vascularis
Which ions are of high and low concentration in the endolymph, respectively?
High K+
Low Na+
The perilymph within the scala vestibuli and scala tympani is almost identical to which ECF?
CSF due to their direct communication with the subarachnoid space
Hair cells at the endolymph have a negative intracellular potential of ___ millivolts with respect to the perilymph
−70 mV
Hair cells at the perilymph have a negative intracellular potential of ___ millivolts with respect to the endolymph
-150mV
The possible rapidly acting neurotransmitter release by hair cells at their synapses causing depolarization:
Glutamate
Sequence of Hair cell receptor excitation:
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
Sound localization is more precise discriminating:
direction or intensity?
Direction than detecting intensities as it does not depend on external factors and is only concerned with time.
Specific nuclei responsible for detecting time lag of sound entering the ears.
Medial Superior Olivary nucleus
Specific nucleus responsible for detecting direction of sounds by comparing the intensities of the sounds reaching the ears.
Lateral Superior Olivary Nucleus
Sound waves cause basilar fibers from the base of cochlea to move towards which window of the ear?
Round window
