Ear & Audition Flashcards
What is the outer ear called?
Auricle
What is the pinna?
Part of the outer ear that creates a funnel approx 1 inch or 25mm. Close by the tympanic membrane (eardrum)
What closes the pinna?
Tympanic membrane (eardrum)
What is the role of the outer ear?
To direct and amplify sound further into the ear
What is the resonant frequency of the ear?
3,430 Hz
What the role of the Middle Ear?
Transmits sound from the tympanic membrane from the air into fluid in the inner ear (labyrinth)
What are the smallest bones in the body, found in the body?
Malleus (hammer), Incus (anvil), stapes (stirrup)
What is the oval window?
Membrane covered opening leading to the inner ear
What’s the round window?
Vibrates with opposite phase vibrations entering the inner ear via the oval window
What is the eustachian tube?
It is a tube in the middle ear connecting to the nasal pharyngeal regions thats role is to equalise atmospheric pressure from outside to inside the ear
What is a disease of the middle ear?
Otitis Media (OM)/Glue Ear
What is otitis media (OM) or Glue Ear?
Inflammation and fluid accumulation in the middle ear. Can cause conductive hearing loss as it makes it harder for sound to be conducted from the outer to inner ear
What are the muscles that regulate the middle ear?
Tensor malleus and stapideus
What are the tensor malleus and stapideus?
The smallest striated muscles in the body that regulate middle-ear function. They attenuate transmission by 30%
What part of the ear is an impedance transformer or amplifer?
The middle ear
What is the cochlea?
A structure in the inner ear that is a fluid filled coiled tube with 2.75 turns.
What are the sensory organs for balance?
Semicircular ducts
What are semi-circular ducts in the inner ear?
Sensory organs for balance
What joins the foremen ovale (oval window)?
Scala vestibuli
Where is the organ of corti located in the inner ear?
In the scala media
What does the organ of corti do?
Transduces electrical impulses; transduces vibrational energy from a sound into an action potential (nerve impulse)
Where do hair cells in the inner ear sit?
On the basiliar membrane in the organ of corti in the cochlea
The cochlea/basilar membrane is wider and then gets narrower and less stiff at the end. What is this called?
Tonotopic as it resonates higher frequencies at the wider side and lower frequencies at the narrower end
How does the vibration get transduced in the inner ear?
Vibrations at the basilar membrane transfer a ‘shearing’ force on the hair cells above it by movement of the tectorial membrane bending the stereocilia on hair cells. It has a single K+ channel that opens in the shearing process causing an action potential down afferent signals (as it depolarises) and releases neurotransmitters to CN VII (vestibulocochlear nerve).
What is the sylvian fissure and where is it?
It’s surrounded by the secondary auditory cortex and organised into frequency columns, tonotopically like the cochlea
How many types of hearing loss are there and what are they?
4 types;
1) Auditory Processing Disorders
2) Conductive Hearing Loss
3) Sensorineural Hearing Loss
4) Mixed Hearing Loss
What is Auditory Processing Disorder?
The brain having issues processing the information contained in sound like understanding speech or working out the location of sounds
What is conductive hearing loss?
Problem with the outer or middle ear that interferes with passing sound to the inner ear
What is sensorineural hearing loss?
When the cochlea and/or auditory nerve is unable to send accurate electrical information to the brain.
What form of hearing loss is almost always permanent?
Sensorineural
What is mixed hearing loss?
Both conductive and sensorineural hearing loss
