Semicircular canal

Semicircular canal
Balance Disorder Illustration A.png
Exterior of labyrinth.
Vestibular system's semicircular canal- a cross-section.jpg
Inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid
Latin canalis semicircularis
Gray's subject #232 1049
Artery stylomastoid artery
MeSH Semicircular+Canals

A semicircular canal is one of three semicircular, interconnected tubes located inside each ear. The three canals are the horizontal semicircular canal (also known as the lateral semicircular canal), superior semicircular canal (also known as the anterior semicircular 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 posterior 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 bony labyrinth.

Among species of mammals, the size of the semicircular canals is correlated with their type of locomotion. Specifically, species that are agile and have fast, jerky locomotion have larger canals relative to their body size than those that move more cautiously.[2]

Additional images

Transverse section of a human semicircular canal and duct  
Illustration of otolith organs  
Semicircular canals on skull X-ray  

References

  1. ^ Orientation of Human Semicircular Canals Measured by Three-Dimensional Multiplanar CT Reconstruction, Journal of the Association for Research in Otolaryngology, 6 (3), 2005.
  2. ^ Spoor, F.; T. Garland, Jr., G. Krovitz, T. M. Ryan, M. T. Silcox, and A. Walker (2007). "The primate semicircular canal system and locomotion". Proceedings of the National Academy of Science U.S.A. 104 (26): 10808–10812. doi:10.1073/pnas.0704250104. PMC 1892787. PMID 17576932. http://www.biology.ucr.edu/people/faculty/Garland/Spoor_et_al_2007.pdf. 

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Look at other dictionaries:

  • semicircular canal — n. any of the three loop shaped, tubular, fluid filled structures of the inner ear that serve to maintain balance in the organism: see EAR1 …   English World dictionary

  • semicircular canal — noun one of three tube loops filled with fluid and in planes nearly at right angles with one another; concerned with equilibrium • Hypernyms: ↑sense organ, ↑sensory receptor, ↑receptor • Part Holonyms: ↑inner ear, ↑internal ear, ↑labyrinth, ↑ …   Useful english dictionary

  • semicircular canal — UK / US noun [countable] Word forms semicircular canal : singular semicircular canal plural semicircular canals medical one of the three tubes in your inner ear that is shaped like half of a circle and is important for balance …   English dictionary

  • semicircular canal — semi·cir·cu·lar canal .sər kyə lər n any of the loop shaped tubular parts of the labyrinth of the ear that together constitute a sensory organ associated with the maintenance of bodily equilibrium, that consist of an inner membranous canal of the …   Medical dictionary

  • semicircular canal — each of the three fluid filled sections of the ear canal that assist in maintaining balance and hearing …   English contemporary dictionary

  • semicircular canal — semicir′cular canal′ n. anat. any of the three curved tubular canals in the inner ear, associated with the sense of equilibrium …   From formal English to slang

  • semicircular canal — noun Date: 1748 any of the loop shaped tubular parts of the labyrinth of the ear that together constitute a sensory organ associated with the maintenance of bodily equilibrium see ear illustration …   New Collegiate Dictionary

  • semicircular canal — Anat. any of the three curved tubular canals in the labyrinth of the ear, associated with the sense of equilibrium. See diag. under ear. [1740 50] * * * …   Universalium

  • semicircular canal — /sɛmiˌsɜkjələ kəˈnæl/ (say semee.serkyuhluh kuh nal) noun any of three curved tubular canals in the labyrinth of the ear, concerned with equilibrium …   Australian English dictionary

  • Horizontal semicircular canal — Infobox Anatomy Name = PAGENAME Latin = canalis semicircularis lateralis GraySubject = 232 GrayPage = 1049 Caption = Interior of right osseous labyrinth. MapPos = Cochlea System = Artery = stylomastoid artery MeshName = Semicircular+Canals… …   Wikipedia

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