Utricle ( ear ) - wikipedia Utricle ( ear ) For other uses, see Utricle. Utricle Posterior Canal Superior Canal Utricle Horizontal Canal Vestibule Cochlea Saccule Components of the inner ear including the utricle Details Identifiers Latin utriculus TA A15. 3.03. 063 FMA 61113 Anatomical terminology ( edit on Wikidata ) The utricle, or utriculus ( Latin : utriculus, diminutive of uter, meaning `` leather bag '' ), along with the saccule, is one of the two otolith organs located in the vertebrate inner ear. The utricle and the saccule are parts of the balancing apparatus ( membranous labyrinth ) located within the vestibule of the bony labyrinth ( small oval chamber ). These 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. Contents 1 Structure 1.1 Histology 2 Function 3 See also 4 References 5 External links Structure Inner ear, showing utricle near centre 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. The macula of utricle is a thickening in the wall of the utricle where the epithelium contains vestibular hair cells that allows a person to perceive changes in longitudinal acceleration as well as effects of gravity. The gelatinous layer and the statoconia together are referred to as the otolithic membrane, where the tips of the 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. Within the utricle is a small 2 by 3 mm patch of hair cells called the macula of utricle. The macula of utricle, which lies horizontally on the floor of the utricle, contains the hair cells. These hair cells are mechanoreceptors which consist of 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 otolithic membrane. 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. Histology The macula consists of three layers. The bottom layer is made of sensory hair cells which are embedded in the 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. 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. 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. 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. 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. Function See also : Balance ( ability ) Illustration of otolith organs showing detail of utricle, otoconia, endolymph, cupula, macula, hair cell filaments, and saccular nerve 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. 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. See also Wikimedia Commons has media related to Utricle ( ear ). This article uses anatomical terminology ; for an overview, see Anatomical terminology. References This article incorporates text in the public domain from the 20th edition of Gray 's Anatomy ( 1918 ) Jump up ^ Moores, Kieth L. `` Essential Clinical Anatomy '' Lippincott Williams & Wilkins ; Second Edition ( 2002 ). Jump up ^ Johnsson, LG ; Hawkins JE, Jr ( Sep 22, 1967 ). `` Otolithic membranes of the saccule and utricle in man. ''. Science. 157 ( 3795 ) : 1454 -- 6. PMID 5341324. doi : 10.1126 / science. 157.3795. 1454. Jump up ^ Saladin, Kenneth S. ( 2010 ). Anatomy & physiology : the unity of form and function ( 5th ed. ). Dubuque : McGraw - Hill. ISBN 0073525693. Jump up ^ Cohen, B ; Suzuki, JI ; Raphan, T ( Oct 3, 1983 ). `` Role of the otolith organs in generation of horizontal nystagmus : effects of selective labyrinthine lesions. ''. Brain Research. 276 ( 1 ) : 159 -- 64. PMID 6626994. doi : 10.1016 / 0006 - 8993 ( 83 ) 90558 - 9. Jump up ^ Saladin, Kenneth S. Anatomy & Physiology : the Unity of Form and Function. Dubuque : McGraw - Hill, 2010. Print. External links Diagram at ipfw.edu Anatomy of hearing and balance Outer ear Auricle helix antihelix tragus antitragus intertragic notch earlobe Ear canal Auricular muscles Eardrum umbo pars flaccida Middle ear Tympanic cavity Medial structures oval window round window secondary tympanic membrane prominence of facial canal promontory of tympanic cavity Posterior structures mastoid cells aditus to mastoid antrum pyramidal eminence Ossicles Malleus superior ligament lateral ligament anterior ligament Incus superior ligament posterior ligament Stapes annular ligament Muscles stapedius tensor tympani Auditory tube / Eustachian tube Torus tubarius Inner ear / ( membranous labyrinth, bony labyrinth ) Auditory system / Cochlear labyrinth General cochlea Vestibular duct Helicotrema Tympanic duct Modiolus Cochlear cupula Perilymphatic space Perilymph Cochlear aqueduct Cochlear duct / scala media Reissner 's / vestibular membrane Basilar membrane Reticular membrane Endolymph Stria vascularis Spiral ligament Organ of Corti stereocilia tip links Tectorial membrane Sulcus spiralis externus internus Spiral limbus Cells Claudius cell Boettcher cell Vestibular system / Vestibular labyrinth Vestibule Utricle macula Saccule macula Kinocilium Otolith Vestibular aqueduct endolymphatic duct endolymphatic sac Ductus reuniens Semicircular canals Superior semicircular canal Posterior semicircular canal Horizontal semicircular canal Ampullary cupula Ampullae crista ampullaris Retrieved from `` https://en.wikipedia.org/w/index.php?title=Utricle_(ear)&oldid=782561113 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Ear Vestibular system Hidden categories : Medicine infobox template using GraySubject or GrayPage Articles containing Latin - language text Talk Contents About Wikipedia Català Čeština Euskara Italiano Polski Português Српски / srpski Edit links This page was last edited on 27 May 2017, at 18 : 26. 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Question: the major function of the utricle and saccule in the vestibule is
Answer: to detect motion and orientation