Relationship Between Semicircular Canals and Extraocular Muscles

Update item information
Identifier SCC_stimulation
Title Relationship Between Semicircular Canals and Extraocular Muscles
Subject Extraocular Muscles
Creator Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, Emergency Medicine, and Medicine, The Johns Hopkins School of Medicine
Description Figure 1: When stimulated, each of the 6 angular acceleration detecting semicircular canals (3 on the right and 3 on the left) responds with a conjugate eye movement, with the vector(s) indicated below. PC=posterior canal; HC=horizontal (also known as lateral) canal; AC=anterior (also known as superior) canal. Figure 2: When the right AC is stimulated as in right AC benign paroxysmal positional vertigo (BPPV), excitatory slow phases that are upward and torsional (towards left ear) are generated. This is due to contraction of the right superior rectus (up and incycloduction OD) and left inferior oblique (up and excycloduction OS) muscles. Fast phases in the opposite direction - downbeat and torsional towards the right (ipsilateral) ear - are then seen clinically. Figure 3: When the right HC is stimulated as in a rapid righward head turn, the vestibulo-ocular reflex (VOR) results in the eyes moving conjugately to the left (to avoid retinal/foveal slippage off the intended target) via contraction of the right medial rectus and left lateral rectus muscles. Figure 4: When the right PC is stimulated as in right PC benign paroxysmal positional vertigo (BPPV), excitatory slow phases that are downward and torsional (towards left ear) are generated. This is due to contraction of the right superior oblique (down and incycloduction OD) and left inferior rectus (down and excycloduction OS) muscles. Fast phases in the opposite direction - upbeat and torsional towards the right (ipsilateral) ear - are then seen clinically. Figure 5: Figures 2, 3, and 4 are combined here so that the extraocular muscles stimulated with excitation of the right PC, HC, and/or AC can be seen simultaneously.
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 2017-11
Type Image
Format image/jpeg
Relation is Part of NOVEL: Neuro-ophthalmology Virtual Education Library Examination Collection
Rights Management Copyright 2017. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright
Holding Institution Spencer S. Eccles Health Sciences Library, University of Utah, 10 N 1900 E, SLC, UT 84112-5890
Collection Neuro-ophthalmology Virtual Education Library: NOVEL http://NOVEL.utah.edu
Language eng
ARK ark:/87278/s6bk593f
Setname ehsl_novel_gold
Date Created 2017-11-29
Date Modified 2021-05-06
ID 1282767
Reference URL https://collections.lib.utah.edu/ark:/87278/s6bk593f
Back to Search Results