Semicircular canals

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Semicircular canals
Exterior of labyrinth.
Latin	canalis semicircularis
Gray's	subject #232 1049
System
MeSH	A09.246.631.663
Inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid

The semicircular canals are three half-circular, interconnected tubes located inside each ear. The three canals are the horizontal semicircular canal, superior semicircular canal (aka anterior semicricular canal), and the posterior semicircular canal.

The canals are aligned approximately orthogonally to one another. The horizontal canal is aligned roughly horizontally in the head. The superior and anterior canals are aligned roughly at a 45 degree angle to a vertical plane drawn from the nose to the back of the skull. ^[1] Thus, the horizontal canal detects horizontal head movements (such as when doing a pirouette), while the superior and posterior canals detect vertical head movements.

Each canal is filled with a fluid called endolymph and contains a motion sensor with little hairs (cilia) whose ends are embedded in a gelatinous structure called the cupula. As the skull twists in any direction, the endolymph is thrown into different sections of the canals. The cilia detect when the endolymph rushes past, and a signal is then sent to the brain.

The Semicircular canals are a component of the Labyrinth.

Contents 1 Additional images 2 See also 3 References 4 External links

[edit] Additional images

Gray927.png Transverse section of a human semicircular canal and duct

Illustration of otolith organs

[edit] See also

[edit] References

[edit] External links

v·d·e Sensory system: Auditory and Vestibular systems
Outer ear	pinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) • Ear canal
Middle ear	Eardrum (Umbo) • Ossicles (Malleus, Incus & Stapes) • Stapedius • Tensor tympani • Eustachian tube (Torus tubarius)
Inner ear/Labyrinth	Bony labyrinth (Vestibule) • Membranous labyrinth Oval window • Helicotrema • Round window Cochlea: Spiral ganglion • Modiolus • Cochlear duct/scala media (Endolymph, Stria vascularis, Spiral ligament, Organ of Corti) • Scala vestibuli and Scala tympani (Perilymph) Reissner's/vestibular membrane • Basilar membrane • Tectorial membrane Organ of Corti: Hair cells • Stereocilia • Sulcus spiralis (externus, internus) • Limbus spiralis
Vestibular system	Static/translations: Utricle (Macula) - Saccule (Macula, Endolymphatic sac, Endolymphatic duct) - Kinocilium - Otolith Kinetic/rotations: Semicircular canals (Superior, Posterior, Horizontal) • Cupula • Ampullae (Crista ampullaris)
Brain (auditory)	Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex

This page uses content from the English-language version of Wikipedia. The original article was at Semicircular canal. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.