PSYC1002 Lecture Notes - Lecture 15: Semicircular Canals, Inner Ear, Eardrum
19 May 2018
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Screen clipping taken: 15/11/2017 11:05 PM
Assists with control of gaze and posture
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Sensory structures with receptor cells that detect gravitational forces incl angular and
linear head accelerations in space
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Inner ear - contains labyrinth
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Houses 5 sensory organs which provide input to vestibular system
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Fluid filled, bends cupula and underlying hair cells
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e.g. still dizzy after stop spinning
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3 semicircular canals (angular accelerometers)
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Sense gravity
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2 otoliths (linear accelerometers)
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Screen clipping taken: 15/11/2017 11:07 PM
Bending vestibular hair-cell receptor in its preferred direction EXCITES NEURON (in opp
direction INHIBITS neuron)
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Labyrinth
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Gaze, posture, balance - Inner ear , Vestibular system
L4 - the ear
Wednesday, 15 November 2017
11:05 PM
perception Page 1
Screen clipping taken: 15/11/2017 11:14 PM
Mechanical problem in inner ear
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Due to calcium carbonate crystals normally embedded in gel in utricle, becoming
dislodged and migrate into one or more of the semicircular canals (NOT SUPPOSED TO
BE HERE)
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When enough crystals accumulate, interfere with normal fluid movements which canals
use to sense head motion
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Cause inner eat to send false signals to brain that create sensation of vertigo
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Screen clipping taken: 15/11/2017 11:17 PM
e.g. Benign Paroxysmal Positional Vertigo (BPPV)
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Angular and linear
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When moving ourselves we generate large, rapid and complex head movements
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Consequences on motion of objects in our visual field
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Need info about head movement to make precise and rapid compensatory eye
movements to stabilise images of objects on retina
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Vestibuloocular reflex (VOR)
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Effect of head movements
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perception Page 2
Screen clipping taken: 15/11/2017 11:19 PM
Sound and hearing- Middle ear, inner ear
Middle ear
Transmits eardrum's vibrations to the oval window, which transmits them through the fluid
filled cochlea
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Ossicles - 3 smallest bones in body: Malleus, incus, stapes
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Greater mechanical energy needed to transmit sound waves through the denser fluid
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Perilymphatic fluid - fills cochlea, denser than ear offering more resistance
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At the air fluid filled boundary, most of the incoming sound reflected, rather than
transmitted
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Ossicles transfer energy generated by air pressure applied to the larger SA of the
eardrum to the 20x smaller oval window
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Eustachian tube equalises pressure everytime you swallow or yawn, connected to
throat
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For transduction - air pressure in middle ear = atmospheric pressure outside eardrum
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Main function: impedance matching
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perception Page 3
Document Summary
Gaze, posture, balance - inner ear , vestibular system. Sensory structures with receptor cells that detect gravitational forces incl angular and linear head accelerations in space. Houses 5 sensory organs which provide input to vestibular system. Fluid filled, bends cupula and underlying hair cells e. g. still dizzy after stop spinning. Bending vestibular hair-cell receptor in its preferred direction excites neuron (in opp direction inhibits neuron) perception page 1. Screen clipping taken: 15/11/2017 11:14 pm e. g. benign paroxysmal positional vertigo (bppv) Due to calcium carbonate crystals normally embedded in gel in utricle, becoming dislodged and migrate into one or more of the semicircular canals (not supposed to. When enough crystals accumulate, interfere with normal fluid movements which canals use to sense head motion. Cause inner eat to send false signals to brain that create sensation of vertigo. When moving ourselves we generate large, rapid and complex head movements. Consequences on motion of objects in our visual field.
