The Ear Flashcards
What does the outer ear consist of? (From outermost to inner most)
Pinna
Auditory Canal
Skull and bone
What does the middle ear consist of? (From outermost to innermost)
Tympanic membrane (eardrum)
Malleus
Incus
Stapes
Oval window (between middle and inner ear)
Round window (between middle and inner ear)
Eustachian tube
What does the inner ear consist of? (From outermost to innermost)
Oval window and round window connect middle and inner ear
Semicircular canals
Cochlea
Auditory nerve to brain
What is the perilymph
Fluid in the vestibular and tympanic canals
What is the endolymph, and give a difference to perilymph composition
Fluid in the cochlear duct
More K+ than perilymph
True or false:
Organ of Corti rests on the Basilar membrane?
True
True or false:
The Basilar membrane has stiff fibres near the apex to detect high frequency?
False, the Basilar membrane has stiff fibres near the OVAL WINDOW to detect high frequency
True or false:
The Basilar membrane has floppy fibres near the apex to detect low frequency?
True
True or false?
The Basilar membrane detects low frequency (low notes) at the apex and high frequency (high notes) at the base near the oval window?
True
In the Basilar membrane what are the lengths of basilar fibres related to where they are positioned?
Basilar fibres are shorter near the oval window than the apex
How many rows of outer hair cells in the Organ of Corti?
Three
How many rows of inner hair cells in the Organ of Corti?
One
Fill in the gaps:
Stereocilia on the _____ surface of the hair cells project into the ____ membrane.
How many stereocilia are there on this surface for each hair cell?
Stereocilia on the APICAL surface of the hair cells project into the TECTORIAL membrane
40-80 stereocilia on the apical surface of each hair cell.
What is the difference between the tympanic membrane and the tectorial membrane?
Tympanic membrane is the eardrum (middle ear).
Tectorial membrane is present in the cochlea (inner ear), and runs parallel with the basilar membrane.
How are the sensory neurones activated in the Organ of Corti?
Fluid movement in the cochlear duct causes part of the basilar membrane to vibrate.
Stereocilia on the hair cells bend, depolarising the hair cells.
Neurotransmitter is released.
Sensory neurones activated.
Cochlear branch of vestibulo-cochlear nerve conveys message to brain.
Fill in the gaps:
Sound waves are transmitted from the scala ____ to the scala ____ via the _______
Sound waves are transmitted from the scala VESTIBULI to the scala TYMPANI via the HELICOTREMA
What is the scala tympani?
The lower bony passage of the cochlea.
What is the scala vestibuli?
The upper bony passage of the cochlea.
True or false:
Semicircular canals are bony on the outside?
True
What fills the membrane inside the semicircular canals?
Endolymph
What is the vestibular apparatus?
Three semicircular canals in the inner ear. They are important for balance.
What are otoliths?
A calcium carbonate structure in the saccule or utricle of the inner ear. Motions of the head cause the otoliths to pull on the hair cells, stimulating the vestibular nerve. - Internet
Where are the utricle and saccule found?
What do they contain?
What is their function?
Located in semi-circular canals.
Contain maculae & otoliths for detecting head movement in forwards/backwards rotation.
Responsible for maintenance of balance.
What are maculae?
Receptors in wall of saccule and utricle.
Generate impulses carried by Vestibular branch of Vestibulochlear nerve in response to changes in the pull of gravity.
Important for detecting head movement in forwards/backwards rotation.
