semicircular


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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.

sem·i·cir·cu·lar

(sem'ē-sir'kyū-lăr),
Forming a half circle or an incomplete circle.
Synonym(s): semiorbicular

semicircular

(sĕm″ē-sŭr′kū-lăr) [″ + circulus, a ring]
In the form of a half circle.

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 ?
They found that the inner ears of living cheetahs differ markedly from those of all other felids alive today, with a greater overall volume of the vestibular system and longer anterior and posterior semicircular canals.
Of the three cases of unsteady walking, one had left-side semicircular canal paresis, 1 had bilateral semicircular canal paresis and another who had normal vestibular function was complicated with severe visual loss.
Os sintomas da Sindrome da Deiscencia do Canal Semicircular Superior podem ser semelhantes aos sintomas de doencas como: otosclerose e disfuncao tubaria, doenca de Meniere, disfuncao temporo-mandibular [8], o que pode retardar o diagnostico.
sup][14] Briefly, under general anesthesia, cortical mastoidectomy was performed with identification of the horizontal semicircular canal, tegmen, sigmoid sinus, and mastoid antrum after making a postauricular incision.
When you move your head, fluid in the semicircular canals moves around.
The contract is to perform the responsibilities of the investor~s supervision of construction works on: "construction of two reservoirs, reservoir deluge defenses concave edges with spurs, strengthening the outlet of the culvert, the reconstruction of five culverts on semicircular, execution spurs of rip-rap, the reconstruction of three degrees with beards on the rapids and securing landslide in the village of posada rybotycka and boryslawka, fredropol municipality "includes the following scope of work:
1) The relationship between the initial operating frequency f and the height of the semicircular combinatorial symmetrical radiators H is:
Of the surgical options available most popular is the posterior semicircular canal occlusion technique which has high success rates with low post-operative complications (5,6).
The Epson 1815 projectors are mounted on the ceiling in a semi-circular formation and are controlled by a single computer, and a 180-degree interactive computer screen, which consists of nine individual screens also arranged in a semicircular shape.
Going upstairs via the magnificent sweeping semicircular staircase, there is a a galleried landing.
La nueva sede de la Academia de Ciencias de California cuenta con uno de los museos mas sorprendentes del mundo: el Living Museum de San Francisco, dedicado a la historia natural e integrado por un planetario con un sistema Imax con una pantalla semicircular de 180[grados], una pequena selva tropical, un pantano y un arrecife con mas de 4,000 peces.