Ear Physiology Flashcards
What role does the external ear play in hearing?
Collects sound
What role does the middle ear play in hearing?
Amplifies sound
What role does the inner ear play in hearing?
Transduces sounds
What is the speed of sound in air?
330m/s
Does sound travel faster or slower in water than air?
Faster
What frequencies should humans hear ?
20Hz to 20 000 Hz
What range of frequencies are tested on an audiogram?
250Hz to 6000Hz
What does the frequency of a sound wave do?
Dictates how high or low
What does the amplitude of a sound wave do?
Dictates loudness
In the middle ear, how is sound amplified?
Stapes hits against the oval window with greater force when vibrations are higher
What ligament suspends the stapes bone?
Annular ligament
What muscles are related to the stapes bone?
Stapedius
Tensor tympani
What muscles open the Eustachian tube?
Tensor veli palatini
Levator palatine
What manoeuvre can be done to equalise the ears?
Valsalva manoeuvre
What can cause glue ear to be more common?
Cleft palate which causes the muscles which open the eustachian tube to be dysfunctional
Through which window is sound waves transmitted?
Oval
What is the round window for?
Allows pressure to leave
Where is the sound actually perceived?
The fine hairs on the cochlea
What nerve transmits the sound vibrations to the brain?
Cochlear nerve
What bone is the inner ear located in?
Petrous part of the temporal bone
Where is perilymph?
Within the bony labyrinth
Where is the endolymph?
Within the membranous labyrinth
What makes up the membranous labyrinth?
3 semicircular ducts- anterior, posterior and lateral
What connects each semicircular duct to its base- the utricle?
The ampulla
What sensory organ is contained within the ampulla?
Cristae ampullaris
What happens when endolymph moves against the cristae ampullaris?
Hair cells become depolarised which sets up an action potential
What separates the endolymph and perilymph?
Basilar membrane
How does gentamicin cause tinnitus?
It causes damage to the outer hair cells
What is another name for stereo cilia?
Inner hair cells
What is meant by tonotopic organisation of the cochlea?
Different areas of the basilar membrane are responsible for different frequencies of sound
Where it the apex of the cochlea?
Furthest from the round window i.e. centre of spiral
What are the two otolith organs called?
Utricle
Saccule
What structure is responsible for vertigo and what are they made of?
Otoconia
Calcium carbonate crystals
What is special about the orientation of the semicircular canals?
They are orientated at 90 degrees to each other and are paired.
What causes deflection?
Movement of endolymph by bodily movement causes the stereocilia to deflect
What is spontaneous nystagmus?
Movement of the eye without a stimulus
