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circle

 [ser´k'l]
a round figure, structure, or part.
Berry's c's charts with circles on them for testing stereoscopic vision.
cerebral arterial circle circle of Willis.
Minsky's circle a device for the graphic recording of eye lesions.
sensory circle a body area within which it is impossible to distinguish separately the impressions arising from two sites of stimulation.
circle of Willis the anastomotic loop of blood vessels near the base of the brain. Called also cerebral arterial circle.

cir·cle

(ser'kĕl),
1. anatomy a ring-shaped or anular structure or group of structures, as formed by anastomosing arteries or veins, or by connected (communicating) nerves.
2. A line or process with every point approximately equidistant from the center.
Synonym(s): circulus [TA]
[L. circulus]

circle

/cir·cle/ (ser´k'l) a round structure or part.
cerebral arterial circle  c. of Willis.
Berry's circles  charts with circles on them for testing stereoscopic vision.
defensive circle  the coexistence of two conditions which tend to have an antagonistic or inhibiting effect on each other.
circle of Haller  a circle of arteries in the sclera at the site of the entrance of the optic nerve.
Minsky's circles  a series of circles used for the graphic recording of eye lesions.
circle of Willis  the anastomotic loop of vessels near the base of the brain.

circle

Etymology: L, circulus
(in anatomy) a circular or nearly circular structure of the body, such as the circle of Willis and circle of Zinn. circular, adj.

cir·cle

(sĭr'kĕl)
1. A ring-shaped structure or group of structures.
Synonym(s): circulus (1) [TA] .
2. A line or process with every point equidistant from the center.
[L. circulus]

cir·cle

(sĭr'kĕl)
anatomy ring-shaped or anular structure or group of structures, as formed by anastomosing arteries or veins, or by connected (communicating) nerves.
[L. circulus]

circle

a round figure, structure or part.

circle block
see ring block.
ciliary arterial circle
formed from the anterior ciliary arteries; lies within the ciliary muscle.
iridial arterial circle
formed from the posterior long ciliary arteries and supplying blood to the iris.
iridial vascular circle
a ring of vessels formed by the anterior ciliary arteries; provide fine branches to the iris and ciliary body.
circle of safety
circle system
see breathing circuit.
circle test
walking a horse in a small circle, first one direction then the other, is used in a neurological examination to detect ataxia and abnormalities in proprioception.
circle of Willis
anastomotic loop of vessels near the base of the brain. See cerebral arterial circle.
References in classic literature ?
Yet so long as it is the highest circle in the imagination of the best heads on the planet, there is something necessary and excellent in it; for it is not to be supposed that men have agreed to be the dupes of anything preposterous; and the respect which these mysteries inspire in the most rude and sylvan characters, and the curiosity with which details of high life are read, betray the universality of the love of cultivated manners.
He pointed them out significantly to Borckman, who stood outside the circle so that no black should be able to come at his back.
At this moment the projectile hung perpendicularly over the circle.
on the other side rises also a man and draws a circle around the circle we had just pronounced the outline of the sphere.
The circle had tightened till he could feel the breaths of the huskies on his flanks.
Then the old woman, with an air of mystery which drew the circle closer round the fire, informed them that she had provided her graveclothes some years before,--a nice linen shroud, a cap with a muslin ruff, and everything of a finer sort than she had worn since her wedding day.
One by one the tribe swung down from their arboreal retreats and formed a circle about Tarzan and his vanquished foe.
Not letting the abbe and Pierre escape, Anna Pavlovna, the more conveniently to keep them under observation, brought them into the larger circle.
Again and again the Arabs charged, at last forming a stationary circle about the little fortress, and outside the effective range of the defenders' arrows.
A shadow swung slowly across the ground beside him, and looking up, the ape-man saw Ska, the vulture, wheeling a wide circle above him.
Now and again we could hear the crashing of heavy bodies in the thickets and underbrush, and from the darkness of the other side, across the circle, we could see eyes gleaming in the firelight.
And for twelve years Elam Harnish had continued to grope for gold among the shadows of the Circle.