Semicircular canals
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The semicircular canals are components of the bony labyrinth within the petrous temporal bone (PTB) along with the cochlea and vestibule. They contain the semicircular ducts, part of the membranous labyrinth which are responsible for kinetic balance.
Gross anatomy
There are three semicircular canals on each side, each forming two thirds of a full circle which are oriented perpendicular (at right angles) to each other. They all open into the vestibule. TheThey have differing and variable lengths but uniform diameters of approximately 1 mm.
Superior (anterior) semicircular canal (SSCC)
- oriented in the vertical plane perpendicular (transverse) to the long axis of the PTB
- it lies under the arcuate eminence on the anterior surface of the PTB
- hair cells of the superior semicircular duct supplied by the superior division of the vestibulocochlear nerve (CN VIII)
Posterior semicircular canal (PSCC)
- oriented in the vertical plane parallel to the long axis of the PTB
- hair cells of the posterior semicircular duct supplied by the inferior division of CN VIII
Lateral (horizontal) semicircular canal (LSCC)
- oriented 30 degrees to the horizontal
- shortest of the semicircular canals
- hair cells of the lateral semicircular duct supplied by the superior division of CN VIII
Related pathology
-<p>The <strong>semicircular canals</strong> are components of the <a href="/articles/bony-labyrinth">bony labyrinth</a> within the <a href="/articles/petrous-part-of-temporal-bone">petrous temporal bone</a> (PTB) along with the <a href="/articles/cochlea">cochlea</a> and <a href="/articles/vestibule-ear">vestibule</a>. They contain the <a href="/articles/semicircular-ducts">semicircular ducts</a>, part of the <a href="/articles/membranous-labyrinth">membranous labyrinth</a> which are responsible for kinetic balance.</p><h4>Gross anatomy</h4><p>There are three semicircular canals on each side, each forming two thirds of a full circle which are oriented perpendicular (at right angles) to each other. They all open into the vestibule. The have differing and variable lengths but uniform diameters of approximately 1 mm.</p><h5>Superior (anterior) semicircular canal (SSCC)</h5><ul>- +<p>The <strong>semicircular canals</strong> are components of the <a href="/articles/bony-labyrinth">bony labyrinth</a> within the <a href="/articles/petrous-part-of-temporal-bone">petrous temporal bone</a> (PTB) along with the <a href="/articles/cochlea">cochlea</a> and <a href="/articles/vestibule-ear">vestibule</a>. They contain the <a href="/articles/semicircular-ducts">semicircular ducts</a>, part of the <a href="/articles/membranous-labyrinth">membranous labyrinth</a> which are responsible for kinetic balance.</p><h4>Gross anatomy</h4><p>There are three semicircular canals on each side, each forming two thirds of a full circle which are oriented perpendicular (at right angles) to each other. They all open into the vestibule. They have differing and variable lengths but uniform diameters of approximately 1 mm.</p><h5>Superior (anterior) semicircular canal (SSCC)</h5><ul>
-<li><a title="Superior semicircular canal dehiscence syndrome" href="/articles/superior-semicircular-canal-dehiscence-syndrome">superior semicircular canal dehiscence syndrome</a></li>- +<li><a href="/articles/superior-semicircular-canal-dehiscence-syndrome">superior semicircular canal dehiscence syndrome</a></li>
-<li><a title="lateral semicircular canal dehiscence syndrome" href="/articles/lateral-semicircular-canal-dehiscence-syndrome">lateral semicircular canal dehiscence syndrome</a></li>- +<li><a href="/articles/lateral-semicircular-canal-dehiscence-syndrome">lateral semicircular canal dehiscence syndrome</a></li>
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