Vestibulo cochlear system. Audition and balance Flashcards
What are the orientations of the 3 semicircular canals?
Lateral, posterior and superior
What is immediately below the middle ear?
Bulb of the internal jugular vein
What does the Eustachian tube connect?
Nasopharynx and middle ear
What is the order of the ossicles from lateral to medial?
Malleus, incus, stapes
How does the stapes connect to the cochlea?
Oval window
Which nerve innervates the outer surface of the tympanic membrane?
V3 division of trigeminal nerve.
Where can pain of the tympanic membrane refer to?
Jaw
Why is otitis media more common in infants?
The eustachean tube is more hosizontal => harder for bacteria in middle ear to drain => easier for bacteria in nasopharynx to migrate to middle ear
How are the ossicles joined?
With synovial joints
What are the 2 muscles in the middle ear that regulate movement of the ossicles?
Tensor tympani and stapedius
Which nerve innervates tensor tympani?
Trigeminal
Which nerve innervates stapedius
Seventh
Which branch of CN7 runs through the middle ear?
Chorda tympani
The bony labyrinth of the inner ear is contained within which bone?
Petrous temporal bone
Which fluid fills the bony labyrinth of the inner ear?
Perilymph
What do we call the swelling of each of the semicircular canals of the vestibular apparatus?
Ampulla
What are the 2 components that are within the vestibule of the inner ear?
Saccule and utricle
What do the saccule and utricle sense?
Static equilibrium (ie orientation of head in space)
What do the semicircular canals sense?
Dynamic equilibrium (ie movement of the head in space)
Which fluid is within the semicircular canals of the inner ear?
Endolymph
Which chamber of the cochlea is the middle one?
Scala media
What joins the scala vestibuli and the scala tympani
The helicotrema
Which fluid is contained in the scala media?
Endolymph
What is unique about endolymph as an extracellular fluid?
It is rich in potassium
What do the stereocilia of inner and outer hairs cells of the organ of Corti sit in?
Tectorial membrane
What is the function of inner hair cells of the organ of Corti?
Conduct afferent auditory signal to brainstem
What is the function of outer hair cells of the organ of Corti?
Amplify movements of the basilar membrane
What is the auditory pathway?
Inner hair cells => bipolar cell => cochlear nuclei => (decussate and ipsilateral) => superior olivary complex => (lateral lemniscus) => inferior colliculus => MGN => A1
What pathway is from the superior olivary complex to the MGN?
Lateral lemniscus
What is the function of the superior olivary complex?
Uses interaural discrepanicies in timing and intensity to localise stimuli in the horizontal plane
Which end of the basilar membrane is wider?
The apex
