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ENT
Auditory Physiology Inner Ear
Built from Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
What’s inside
8 sections · 91 slides
Overview
- Scope of this topic
- Sound energy to neural signal
Cochlear anatomy
- Location of the inner ear
- Bony and membranous labyrinth
- Divisions of the membranous labyrinth
- Dimensions of the human cochlea
- The two cochlear windows
- Basal and apical turns
- The modiolus
- Osseous spiral lamina and the scalae
- Basilar membrane and the cochlear partition
- Reissner's membrane and scala media
- Lateral wall of the membranous labyrinth
- The helicotrema
- Cross-section of the cochlear duct
- Path of the inner ear traveling wave
- Pressure gradient across the cochlear partition
- Gradients of the spiral lamina and basilar membrane
- Stiffness of the basilar membrane
Organ of Corti and inner ear fluids
- Organ of Corti
- The tectorial membrane
- Mechano-transduction by shearing force
- Sensitivity of the cochlea
- Pillars and tunnel of Corti
- The reticular lamina
- Inner versus outer hair cell position
- High magnification of the organ of Corti
- Perilymph
- Endolymph
- Longitudinal flow of endolymph
- Rate of endolymph flow and the endocochlear potential
Traveling wave and tonotopy
- Fluid configuration and the traveling wave
- Tonotopic organisation of the cochlea
- Characteristic frequency
- Unrolled cochlea and the traveling fluid wave
Hair cell function
- Hair cell populations
- Purpose of the hair cells
- Course of the cochlear nerve fibres
- Apical structure of the hair cell
- Arrangement of the stereocilia
- Cross-links and tip links
- Morphology of the inner hair cell
- Inner hair cells as passive transducers
- Positive deflection and depolarisation
- Negative deflection and hyperpolarisation
- Stereocilia, kinocilium and the receptor potential
- Morphology of the outer hair cell
- Outer hair cells as cochlear amplifiers
- Prestin and electromotility
- Inner versus outer hair cell function
Synaptic activity and innervation
- Afferent innervation of the cochlea
- Course of the afferent fibres
- Type I and type II cochlear afferents
- Type I innervation of inner hair cells
- Neurotransmitter release and frequency selectivity
- Evidence base for hair cell synapse physiology
- Glutamate and AMPA receptors
- Spontaneous discharge rates of type I neurons
- Calcium nanodomains at the synaptic ribbon
- Quantal size and multi-vesicular release
- Calcium dependence and phase constancy
- Type II fibres and outer hair cell synapses
- Synaptic ribbons and vesicles at outer hair cells
- Release probability at outer hair cell synapses
- Synaptic dynamics compared
Functional differences between hair cell types
- Basis of the functional differences
- Olivocochlear efferent supply
- Sound encoding by type II afferents
- Central convergence of type I and type II afferents
- Shared and divergent molecular markers
Conclusions
- Summary of inner ear function
- Tonotopy as the organising principle
- Directions for future study
- References
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- Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
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