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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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Forming a half circle or an incomplete circle.
Synonym(s): semiorbicular
Farlex Partner Medical Dictionary © Farlex 2012


(sĕm″ē-sŭr′kū-lăr) [″ + circulus, a ring]
In the form of a half circle.
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
After 2015's The Scene Between (essentially a solo project), Brighton-based Parton began working on Semicircle with current live band members and previous contributors, such as guitarist Sam Dook and rapper Ninja.
The renormalisation group has been used to derive the semicircle law for random matrices in the pioneering work of Brezin and Zee [4].
The semicircle on the sides can be moved up and down to where users find it most convenient.
The 19 performers-11 males and eight females in barong Tagalog and jewel-toned gowns, respectively-were seated in a semicircle at the office's second floor landing.
Others focus on one species, like the Azalea Crescent, a semicircle plot on which Marino has painstakingly cultivated the notoriously slow-growing shrub.
Ace in particular was laid out in nine banks radially on a semicircle. Glowing thyristors stood 3ft tall amongst many other valves, each in themselves an impressive piece of work.
The whole of the British Front that night seemed to be in a semicircle. We had sent up some SOS rockets and no matter where we looked we could see our SOS rockets going up in the air: they were only used when the situation was deemed critical and everybody seemed to be in the same plight as ourselves.
" On the basis of feasibility report, NHAI has made detail project report of semicircle outer ring road comprising 90 metres wide two lanes from each side of the road, including the divider, followed by 30 metres of green belt on the both sides of the road.
Summary: In one classroom, boys and girls aged 9 to 12 sit in a semicircle, small fingers fumbling with their trumpets as their teacher vacillates between words of encouragement and constructive instruction.
Based on orthogonal experiment theory, with the help of theoretical analysis and finite element method software ANSYS, Gao and Li [19, 20] calculated and compared the bearing capacities of U-type steel support in horseshoe roadway, circular roadway, and semicircle arch roadway under different load.
It's like describing a rainbow as just a 'coloured semicircle in the sky', the love you feel for your newborn as 'sort of strong' or Idris Elba massaging your feet as 'ok'.
New Zealand took the lead in the sixth minute as Harry Miskimmnim scored from the top of the semicircle after picking up a rebound.