Auditory Physiology Flashcards
What is the outer ear for?
Helps you collect sound
What is the middle ear for?
Transmission of sound
What is the inner ear for?
The conversion of sound into neural impulses
What is the transmission of sound thru the external part of the ear?
Enters via pinna (auricle) and into the external auditory canal
Then from the canal, where do vibrations reach?
The tympanic membrane
What bone Is the middle ear?
Temporal bone of skull
Sensation to the middle ear is provided by which nerve?
Glossopharngeal nerve (CN9)
What does vibrations of the tympanic membrane cause?
The ossicles to vibrate
What are the ossicles?
3 bones Malleus Incus Stapes MIS
Ossicles
What bones are they?
What do they have between them?
Smallest bones of the body
Synovial joints between them
What do the ossicles then hit on?
Transfer the vibrations to the oval window of the scala vestibuli
The amount of energy transmitted to the inner ear can be lessened by contraction of what 2 small muscles?
What are they innervate by?
What do they connect to?
Tensor tympani
Mandibular division of trigeminal
Attaches to malleus
Stapedius
Facial nerve (CN7)
Stapes
These muscles protect the inner ear from….
But can’t protect it from….
Continuous loud noise
Sudden intermittent loud sounds
What is the inner ear called?
The cochlea (organ of hearing)
What is the cochlear duct filled with?
Endolymph
Extracellular fluid with high conc of K+ & low Na+
What is scala vestibuli and tympani filled with?
Perilymph
Similar to CSF
When waves of pressure get to the oval window of the scala vestibuli, where does it go?
Scala vestibuli—-> helicotrema —-> scala tympani —-> round window (relieves pressure)
Where is the Basilar membrane?
Above scala tympani and below cochlear duct
The base of the Basilar membrane is….. thus sensitive to …..
Narrow and stiff
High frequency’s
The apex of the Basilar membrane is….. thus sensitive to …..
Wider and less stiff
Low frequency’s
What happens to the stereocilia on basilar membrane?
Bent against stationary tectorial membrane
What neurotransmitter is released by the hair cells?
Glutamate onto afferent neurones
This results in APs in the neurons, the axons of which join to form the….
Cochlear branch of the vestibulocochlear nerve
What is the path of the vestibulocochlear nerve, the cochlear branch?
Cochlear nuclei Superior olivary nucleus Inferior colliculus Medial geniculate body Primary auditory cortex, in wernickes area
Where is the primary auditory cortex found and why?
Temporal lobe
Surrounded by wernickes area
Auditory info is interpreted and understood here
What is a way to remember the pathway?
I’M Auditory
Inferior colliculus
Medial geniculate body
Auditory info
Then what must the pathway be for vision?
Superior colliculus
Lateral geniculate body
What does the Corda tympani do and run through?
Branch of the CN5
Conveys taste info from tongue
Runs through middle ear to carry taste messages to brain
Inflammation of the facial nerve can lead to pain where?
Behind the ear
Also paralysis of facial muscles and failure to close eye
What is wernickes area important for?
What happens if wernickes area is damaged?
Processing and understanding language in the brain
Not able to understand questions and speech will be incomprehensible
What does the vestibular system comprise of?
3 semicircular canals filled with endolymph
2 sac like swellings, the utricle and saccule (otolithic organs)
Hair cells
What do the otolithic organs provide info about?
Linear acceleration
Changed in head position in relation to gravity
What nerve is supplied by the vestibular system?
Vestibular branch of the vestibulocochlear nerve (CN8)
What is vestibular info used for?
Control of eye muscles
Reflex mechanisms of maintaining upright posture and balance
Conscious awareness of the position and acceleration of the body - proprioception
