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{{short description|Membranous labyrinth in the vestibule of ear}} |
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{{Other uses|Utricle (disambiguation){{!}}Utricle}} |
{{Other uses|Utricle (disambiguation){{!}}Utricle}} |
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{{Infobox anatomy |
{{Infobox anatomy |
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| Name = Utricle |
| Name = Utricle |
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| Latin = utriculus |
| Latin = utriculus |
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| GraySubject = 232 |
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| GrayPage = 1051 |
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| Width = 280 |
| Width = 280 |
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| Image = {{Inner ear map|Utricle|Inline=1}} |
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| Caption = Components of the inner ear including the utricle |
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| System = |
| System = [[Equilibrioception|Balance]] |
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| part_of = [[Inner ear]] of [[vertebrate]]s |
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The '''utricle''' |
The '''utricle''' and [[saccule]] are the two [[otolith]] organs in the [[vertebrate]] [[inner ear]]. The word utricle comes {{ety|la|uter|leather bag}}. The utricle and saccule are part of the balancing system ([[membranous labyrinth]]) in the vestibule of the [[bony labyrinth]] (small oval chamber).<ref>Moores, Keith L. "Essential Clinical Anatomy" Lippincott Williams & Wilkins; Second Edition (2002).</ref> They use small stones and a viscous fluid to stimulate hair cells to detect motion and orientation. The utricle detects linear accelerations and head-tilts in the horizontal plane. |
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==Structure== |
==Structure== |
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⚫ | The utricle is larger than the saccule and is of an oblong form, compressed transversely, and occupies the upper and back part of the [[Vestibule of the ear|vestibule]], lying in contact with the [[recessus ellipticus]] and the part below it. |
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⚫ |
[[File:Blausen 0329 EarAnatomy InternalEar.png|thumb| |
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⚫ |
The utricle is larger than the saccule and is of an oblong form, compressed transversely, and occupies the upper and back part of the [[Vestibule of the ear|vestibule]], lying in contact with the [[recessus ellipticus]] and the part below it |
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===Macula=== |
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The gelatinous layer and the [[statoconia]] together are referred to as the [[otolithic membrane]], where the tips of the [[Stereocilia (inner ear)|stereocilia]] and [[kinocilium]] are embedded. When the head is tilted such that gravity pulls on the statoconia the gelatinous layer is pulled in the same direction also causing the sensory hairs to bend. |
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{{Infobox anatomy |
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| Name = Macula of utricle |
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| Latin = macula utriculi |
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| Image = bigotolith.jpg |
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⚫ | | Caption = illustration of otolith organs showing detail of utricle, [[otoconia]], [[endolymph]], cupula, [[macula]], [[hair cell]] filaments, and [[saccular nerve]] |
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The macula of utricle ('''macula acustica utriculi''') is a small (2 by 3 mm) thickening lying horizontally on the floor of the utricle where the epithelium contains vestibular hair cells that allow a person to perceive changes in latitudinal acceleration as well as the effects of gravity; it receives the utricular filaments of the [[acoustic nerve]]. |
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The hair cells are mechanoreceptors which have 40 to 70 stereocilia and only one true cilium called a [[kinocilium]]. The kinocilium is the only sensory aspect of the hair cell and is what causes hair cell polarization. The tips of these stereocilia and kinocilium are embedded in a gelatinous layer, which together with the [[statoconia]] form the [[otolithic membrane]].<ref>{{cite journal|last=Johnsson|first=LG|author2=Hawkins JE, Jr|title=Otolithic membranes of the saccule and utricle in man.|journal=Science|date=Sep 22, 1967|volume=157|issue=3795|pages=1454–6|doi=10.1126/science.157.3795.1454|pmid=5341324|bibcode=1967Sci...157.1454J|s2cid=39417066}}</ref> This membrane is weighted with calcium carbonate-protein granules called otoliths. The otolithic membrane adds weight to the tops of the hair cells and increases their inertia. The addition in weight and inertia is vital to the utricle's ability to detect linear acceleration, as described below, and to determine the orientation of the head.<ref>{{cite book|last=Saladin|first=Kenneth S.|title=Anatomy & physiology : the unity of form and function|year=2010|publisher=McGraw-Hill|location=Dubuque|isbn=978-0073525693|edition=5th}}</ref> When the head is tilted such that gravity pulls on the statoconia, the gelatinous layer is pulled in the same direction also, causing the sensory hairs to bend. Labyrinthine activity responsible for the [[nystagmus]] induced by off-vertical axis rotation arises in the otolith organs and couples to the oculomotor system through the velocity storage mechanism.<ref>{{cite journal|last=Cohen|first=B|author2=Suzuki, JI |author3=Raphan, T |title=Role of the otolith organs in generation of horizontal nystagmus: effects of selective labyrinthine lesions.|journal=Brain Research|date=Oct 3, 1983|volume=276|issue=1|pages=159–64|doi=10.1016/0006-8993(83)90558-9|pmid=6626994|s2cid=20083626}}</ref> |
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{{Clear}} |
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===Histology=== |
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The macula consists of three layers. The bottom layer is made of sensory hair cells which are embedded in bottom of a gelatinous layer. Each hair cells consists of 40 to 70 steriocilia and a kinocilium, which lies in the middle of the steriocilia and is the most important receptor. |
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On top of this layer lie calcium carbonate crystals called [[statoconia]] or [[otoconia]]. The otoliths are relatively heavy, providing weight to the membrane as well as inertia. This allows for a greater sense of gravity and motion. |
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Labyrinthine activity responsible for the [[nystagmus]] induced by off-vertical axis rotation arises in the otolith organs and couples to the oculomotor system through the velocity storage mechanism.<ref>{{cite journal|last=Cohen|first=B|author2=Suzuki, JI |author3=Raphan, T |title=Role of the otolith organs in generation of horizontal nystagmus: effects of selective labyrinthine lesions.|journal=Brain Research|date=Oct 3, 1983|volume=276|issue=1|pages=159–64|doi=10.1016/0006-8993(83)90558-9|pmid=6626994}}</ref> |
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That portion which is lodged in the recess forms a pouch or cul-de-sac, the floor and anterior wall of which are thickened and form the '''macula acustica utriculi''', which receives the utricular filaments of the [[acoustic nerve]]. |
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===Microanatomy=== |
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The cavity of the utricle communicates behind with the [[semicircular ducts]] by five orifices. |
The cavity of the utricle communicates behind with the [[semicircular ducts]] by five orifices. |
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==Function== |
==Function== |
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{{See also|Balance (ability)}} |
{{See also|Balance (ability)}} |
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⚫ | The utricle contains mechanoreceptors called hair cells that distinguish between degrees of tilting of the head, thanks to their apical [[stereocilia]] set-up. These are covered by [[otolith]]s which, due to gravity, pull on the stereocilia and tilt them. Depending on whether the tilt is in the direction of the [[kinocilium]] or not, the resulting hair cell polarisation is excitatory (depolarising) or inhibitory (hyperpolarisation), respectively. Any orientation of the head causes a combination of stimulation to the utricles and saccules of the two ears. The brain interprets head orientation by comparing these inputs to each other and to other input from the eyes and stretch receptors in the neck, thereby detecting whether only the head is tilted or the entire body is tipping. The inertia of the otolithic membranes is especially important in detecting linear acceleration. Suppose you are sitting in a car at a stoplight and then begin to move. The otolithic membrane of the macula utriculi briefly lags behind the rest of the tissues, bends the stereocilia backward, and stimulates the cells. When you stop at the next light, the macula stops but the otolithic membrane keeps going for a moment, bending the stereocilia forward. The hair cells convert this pattern of stimulation to nerve signals, and the brain is thus advised of changes in your linear velocity.<ref>Saladin, Kenneth S. Anatomy & Physiology: the Unity of Form and Function. Dubuque: McGraw-Hill, 2010. Print.</ref> This signal to the vestibular nerve (which takes it to the brainstem) does not adapt with time. The effect of this is that, for example, an individual lying down to sleep will continue to detect that they are lying down hours later when they awaken. |
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⚫ |
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⚫ | The utricle contains mechanoreceptors called hair cells that distinguish between degrees of tilting of the head, thanks to their apical [[stereocilia]] set-up. These are covered by [[otolith]] which, due to gravity, pull on the stereocilia and tilt them. Depending on whether the tilt is in the direction of the [[kinocilium]] or not, the resulting hair cell polarisation is excitatory (depolarising) or inhibitory (hyperpolarisation), respectively. Any orientation of the head causes a combination of stimulation to the utricles and saccules of the two ears. The brain interprets head orientation by comparing these inputs to each other and to other input from the eyes and stretch receptors in the neck, thereby detecting whether only the head is tilted or the entire body is tipping. The inertia of the otolithic membranes is especially important in detecting linear acceleration. Suppose you are sitting in a car at a stoplight and then begin to move. The otolithic membrane of the macula utriculi briefly lags behind the rest of the tissues, bends the stereocilia backward, and stimulates the cells. When you stop at the next light, the macula stops but the otolithic membrane keeps going for a moment, bending the stereocilia forward. The hair cells convert this pattern of stimulation to nerve signals, and the brain is thus advised of changes in your linear velocity.<ref>Saladin, Kenneth S. Anatomy & Physiology: the Unity of Form and Function. Dubuque: McGraw-Hill, 2010. Print.</ref> This signal to the vestibular nerve (which takes it to the brainstem) does not adapt with time. The effect of this is that, for example, an individual lying down to sleep will continue to detect that they are lying down hours later when they awaken. |
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Unbent and at rest hairs in the macula have a base rate of depolarization of 90-100 action potentials a second. The brain suppresses this, and we ignore it and know that our body is stabilized. If the head moves or the body accelerates or decelerates, then bending occurs. Depending on the direction of bending, the hair cells will either be excited or inhibited resulting in either an increase or decrease in firing frequency of the hair cells. |
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The macula is also sensitive to linear acceleration as the inertia possessed by the statoconia can also shift the gelatinous layer during increases and decreases in linear velocity. |
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⚫ | [[File:Blausen 0329 EarAnatomy InternalEar.png|thumb|right|[[Inner ear]], showing utricle near centre]] |
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==See also== |
==See also== |
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== References == |
== References == |
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{{Gray's}} |
{{Gray's}} |
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{{ |
{{Reflist}} |
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== External links == |
== External links == |
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* [http://alpha.ipfw.edu/histo-embryo/wwwimagefolder/utricsac.jpg Diagram at ipfw.edu] |
* [http://alpha.ipfw.edu/histo-embryo/wwwimagefolder/utricsac.jpg Diagram at ipfw.edu] |
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* [https://web.archive.org/web/20161209194748/http://www.neurophys.wisc.edu/h%26b/textbook/chap-7.html#Obj2 THE INNER EAR: THE VESTIBULAR APPARATUS] |
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{{Vestibular system}} |
{{Vestibular system}} |
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{{Portal bar|Anatomy}} |
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{{Authority control}} |
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[[Category:Ear]] |
[[Category:Ear]] |
Utricle | |
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Utricle
Components of the inner ear including the utricle
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Details | |
Part of | Inner earofvertebrates |
System | Balance |
Identifiers | |
Latin | utriculus |
TA98 | A15.3.03.063 |
TA2 | 6999 |
FMA | 61113 |
Anatomical terminology |
The utricle and saccule are the two otolith organs in the vertebrate inner ear. The word utricle comes from Latin uter 'leather bag'. The utricle and saccule are part of the balancing system (membranous labyrinth) in the vestibule of the bony labyrinth (small oval chamber).[1] They use small stones and a viscous fluid to stimulate hair cells to detect motion and orientation. The utricle detects linear accelerations and head-tilts in the horizontal plane.
The utricle is larger than the saccule and is of an oblong form, compressed transversely, and occupies the upper and back part of the vestibule, lying in contact with the recessus ellipticus and the part below it.
Macula of utricle | |
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![]()
illustration of otolith organs showing detail of utricle, otoconia, endolymph, cupula, macula, hair cell filaments, and saccular nerve
| |
Details | |
Identifiers | |
Latin | macula utriculi |
TA98 | A15.3.03.063 |
TA2 | 6999 |
FMA | 61113 |
Anatomical terminology |
The macula of utricle (macula acustica utriculi) is a small (2 by 3 mm) thickening lying horizontally on the floor of the utricle where the epithelium contains vestibular hair cells that allow a person to perceive changes in latitudinal acceleration as well as the effects of gravity; it receives the utricular filaments of the acoustic nerve.
The hair cells are mechanoreceptors which have 40 to 70 stereocilia and only one true cilium called a kinocilium. The kinocilium is the only sensory aspect of the hair cell and is what causes hair cell polarization. The tips of these stereocilia and kinocilium are embedded in a gelatinous layer, which together with the statoconia form the otolithic membrane.[2] This membrane is weighted with calcium carbonate-protein granules called otoliths. The otolithic membrane adds weight to the tops of the hair cells and increases their inertia. The addition in weight and inertia is vital to the utricle's ability to detect linear acceleration, as described below, and to determine the orientation of the head.[3] When the head is tilted such that gravity pulls on the statoconia, the gelatinous layer is pulled in the same direction also, causing the sensory hairs to bend. Labyrinthine activity responsible for the nystagmus induced by off-vertical axis rotation arises in the otolith organs and couples to the oculomotor system through the velocity storage mechanism.[4]
The cavity of the utricle communicates behind with the semicircular ducts by five orifices.
The ductus utriculosaccularis comes off of the anterior wall of the utricle and opens into the ductus endolymphaticus.
The utricle contains mechanoreceptors called hair cells that distinguish between degrees of tilting of the head, thanks to their apical stereocilia set-up. These are covered by otoliths which, due to gravity, pull on the stereocilia and tilt them. Depending on whether the tilt is in the direction of the kinocilium or not, the resulting hair cell polarisation is excitatory (depolarising) or inhibitory (hyperpolarisation), respectively. Any orientation of the head causes a combination of stimulation to the utricles and saccules of the two ears. The brain interprets head orientation by comparing these inputs to each other and to other input from the eyes and stretch receptors in the neck, thereby detecting whether only the head is tilted or the entire body is tipping. The inertia of the otolithic membranes is especially important in detecting linear acceleration. Suppose you are sitting in a car at a stoplight and then begin to move. The otolithic membrane of the macula utriculi briefly lags behind the rest of the tissues, bends the stereocilia backward, and stimulates the cells. When you stop at the next light, the macula stops but the otolithic membrane keeps going for a moment, bending the stereocilia forward. The hair cells convert this pattern of stimulation to nerve signals, and the brain is thus advised of changes in your linear velocity.[5] This signal to the vestibular nerve (which takes it to the brainstem) does not adapt with time. The effect of this is that, for example, an individual lying down to sleep will continue to detect that they are lying down hours later when they awaken.
Unbent and at rest hairs in the macula have a base rate of depolarization of 90-100 action potentials a second. The brain suppresses this, and we ignore it and know that our body is stabilized. If the head moves or the body accelerates or decelerates, then bending occurs. Depending on the direction of bending, the hair cells will either be excited or inhibited resulting in either an increase or decrease in firing frequency of the hair cells.
The macula is also sensitive to linear acceleration as the inertia possessed by the statoconia can also shift the gelatinous layer during increases and decreases in linear velocity.
This article incorporates text in the public domain from page 1051 of the 20th edition of Gray's Anatomy (1918)
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Outer ear |
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Middle ear |
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Inner ear |
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