Neuroanatomy 5 Flashcards
How does the Stapes transmit sound to the cochlea?
The flat bottom portion of the stapes moves in and out like a piston in the oval window, which transmits sound vibrations to the fluids of the cochlea
Which mechanisms allow amplification of sounds?
- Eardrum surface area to stapes footplate SA (20:1)
- Lever action of the eardrum (1.3:1)
- Buckling of ear drum (Doubles)
What is the structure of the basilar membrane?
Thick and taut near base
Thin and floppy near apex
How do kinocillium function?
Force towards them opens TRA1 channels and K+ enters, depolarising cell. Force away does opposite
What does the tectorial membrane do and where is it located?
It covers the Cilia in the organ of corti
It vibrates and causes cilia to bend, depending on how they bend the hair cells release neruotransmitter, which is captured in nerve fibres, neural energy is sent to the brain
What are the difference between inner and outer hair cells?
Inner- Main source of afferent signal in CN VIII (Auditory)
Outer- Efferent inputs, control stiffness and amplify membrane vibration
Which protein is responsible for changing the length of the outer hair cell?
Prestin
The vestibular organs have two main functions, what are they?
Semicircular canals- Head rotation
Utricle and saccule- Translational movement and gravity
Describe the vestibular anatomy and functions
Vestibular organs- Detects information about angular and linear velocity
Central processing system- processes info in conjunction with other sensory inputs
Motor output system- compensatory eye movement and body movement generation
The auditory system and vestibular system both have similar mechanisms of action, what are they?
both use hair cells which are deformed by either sound waves (Auditory) or movement (Vestibular)
Deformation of stereocilia towards the kinocilium causes what?
Depolarisation
Which planes do the utricle and saccule sense?
Saccule- Vertical/sagittal plane
Utricle- Horizontal plane
What is Otoconia?
Crystals of calcium carbonate that sit on the otolithic membrane (Otoliths= Ear dust)
