2015 Hearing & Balance

Semicircular canals

Crista ampullaris Schematic of Ampulla Vestibular Hair Cell Em
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  • in contrast to the otoliths, the semicircular canals detect the rate of head rotation (angular acceleration), and are therefore dynamic in function

  • when the head is initially moved, the ampullary crest (and therefore the hair cells) turns with it

  • the endolymph remains in its initial position due to inertia, causing movement of the stereocilia against the cupula and altering the receptor potential (could be depolarizing or hyperpolarizing, depending upon direction)

  • once the head is moving at a constant velocity, the duct fluid moves at the same rate as the hair cells, and the stereocilia are not deflected

  • when the head stops moving, the fluid keeps moving (inertia again), and the receptor potential is again altered, this time in the opposite direction to what occurred at the start of the rotation
Email: Dr. Janet Fitzakerley | ©2015 University of Minnesota Medical School Duluth | Last modified: 7-feb-15 4:45 PM