semicircular canals


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Related to semicircular canals: utricle

semicircular

 [sem″e-ser´ku-lar]
shaped like a half-circle.
semicircular canals the passages in the bony labyrinth of the inner ear that control the sense of equilibrium. Each ear has three semicircular canals (anterior, lateral, and posterior), at approximately right angles to each other, which are filled with fluid and have ampullae (enlarged portions) at one end that contain nerve endings. (See also Plates.)

The semicircular canals respond to movement of the head. When the head changes position in any direction, the fluid in the canal that lies in the plane of movement also moves, but because of its inertia the fluid flow lags behind the head movement. Thus the fluid presses against the delicate hairs of the nerves in the ampulla, and the nerves then register the fact that the head is turning in a given direction so that the body can seek to maintain its equilibrium.

It is the fluid movement in the semicircular canals that causes the feeling of dizziness or vertigo after spinning. When the spinning stops, the fluid in the horizontal canal continues to move for a moment in the direction of the spin, giving a temporary false reading that the head is turning in the other direction. motion sickness is caused by the unusual and erratic motions of the head in an airplane, car, or ship, and the resulting stimulation of the semicircular canals.

semicircular canals (of bony labyrinth)

[TA]
the organ of balance; the three bony tubes of the labyrinth of the inner ear within which the membranous semicircular ducts are located; they lie in planes at right angles to each other and are known as anterior semicircular canal [TA] (canalis semicircularis anterioris [TA]), posterior semicircular canal [TA] (canalis semicircularis posterioris [TA]), and lateral semicircular canal [TA] (canalis semicircularis lateralis [TA]).

semicircular canals

The three tubular structures of the labyrinth of the inner ear, which lie in three different planes and which contain fluid. Movement of the head leads to differential stimulation of nerve endings within the canals and provides the brain with information about orientation.

semicircular canals

the fluid-filled canals present in the inner ear of vertebrates. Usually there are three canals on each side of the head, one in each plane - two vertical and at right angles to each other, and one horizontal and at right angles to the other two. Any movement causes the fluid in the canals to stimulate the receptors (see CRISTA AMPULLARIS) in the AMPULLA at the end of each canal, so that the group of semicircular canals is sensitive to the movements of the head and serves to maintain BALANCE.

semicircular

shaped like a half-circle.

semicircular canals
the passages in the inner ear, in the bony labyrinth concerned with the sense of balance, especially the detection of movement. Each ear has three semicircular canals (anterior, lateral and posterior) situated approximately at right angles to each other. They contain the semicircular ducts.
semicircular ducts
the membranous tubes housed within the semicircular canals.They have enlarged portions at one end, called ampullae, which contain nerve endings, and which are filled with fluid.
The semicircular ducts respond to movement of the head. When the head changes position, the fluid in the duct that lies in the plane of movement also moves but, because of its inertia, the fluid flow lags behind the head movement. Thus the fluid presses against the delicate hairs of the nerves in the ampulla, and these nerves then register the fact that the head is turning in such a direction.
It is the fluid movement in the semicircular ducts that causes the feeling of dizziness or vertigo after spinning. When the spinning stops, the fluid in the horizontal canal continues to move for a moment in the direction of the spin, giving a temporary false reading that the head is turning in the other direction. Motion sickness is caused by the unusual and erratic motions of the head in an airplane, car or ship, and the resulting stimulation of the semicircular ducts. Many animals, even fish, can experience motion sickness.
References in periodicals archive ?
9) In this article, we report the long-term results of our study of the Epley maneuver in the treatment of posterior semicircular canal BPPV.
Free-floating endolymph particles: A new operative finding during posterior semicircular canal occlusion.
Anterior semicircular canal BPPV (AC-BPPV), diagnosed by observation of a similar nystagmus but in a downbeating direction, is not frequent and therapeutic information on this condition is extremely scarce (Epley, 2001; Epley 1992; Semont, Freyss, Vitte, 1988).
Clinical, experimental, and theoretical investigations of the effect of superior semicircular canal dehiscence on hearing mechanisms.
Anytime you're upside down or on your back, the fluid in the semicircular canal has to shift, so it's essentially like practice, and I think that makes sense.
BPPV is often accompained with nausea, vomiting, (27) and is usually caused by dislodged otoconia in the posterior semicircular canal.
Displacement of otoconia from utricle to semicircular canals is held responsible for the development of BPPV.
It's thought that the movement of small, naturally occurring crystals, called otoconia, from one part of the inner ear to another, interfere with the semicircular canals in the inner ear that affect balance, and cause the condition.
To work out if you are moving, the brain relies on information sent by the semicircular canals.
The bony labyrinth of the inner ear is made up of the cochlea, the major organ of hearing, the vestibule and the three semicircular canals which sense head motion and provide input to synchronize movement with visual stimuli.
With T2-weighted image it is possible to assess the cochlea, the semicircular canals, the internal acoustic meatus and the cerebello-pontine angle.
In the presented patient the main risk factor was the Mondini's dysplasia, which is a developmental anomaly of the middle ear characterized by cochlear malformation with dilation of the vestibular aquaduct, vestibule and ampullar ends of the semicircular canals (7).