cone of light

cone (kōn)

1. a solid figure or body having a circular base and tapering to a point.

2. retinal c.

3. in radiology, a conical or open-ended cylindrical structure used as an aid in centering the radiation beam and as a guide to source-to-film distance.

4. in root canal therapy, a solid substance with a tapered form, usually made of gutta-percha or silver, fashioned to conform to the shape of a root canal.

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cone of light  the triangular reflection of light seen on the tympanic membrane.

retinal cone  one of the specialized conical or flask-shaped outer segments of the visual cells, which, with the retinal rods, form the light-sensitive elements of the retina.

twin cones  retinal cone cells in which two cells are blended.

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cone of light

n.

The bright triangular area of reflected light on the tympanic membrane during examination. Also called light reflex.

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cone of light,

1 a triangular reflection observed during an ear examination when the light of an otoscope is focused on the image of the malleus.

2 the group of light rays entering the pupil of the eye and forming an image on the retina.

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cone [kōn]

1. a solid figure or body having a circular base and tapering to a point.

2. one of the conelike structures which, with the rods, form the light-sensitive elements of the retina; the cones make possible the perception of color. See also eye and vision. Called also retinal cone.

3. in radiology, a conical or open-ended cylindrical structure formerly used as an aid in centering the radiation beam and as a guide to source-to-film distance. Cones were commonly attached to the x-ray tube prior to the use of the collimator.

4. in root canal therapy, a solid substance with a tapered form, usually made of gutta-percha or silver, fashioned to conform to the shape of a root canal.

ether cone a cone-shaped device used over the face in administration of ether for anesthesia.

gutta-percha cone in root canal therapy, a plastic radiopaque cone made from gutta-percha and other ingredients, available in standard sizes according to the dimensions of root canal reamers and files; used to fill and seal the canal along with sealer cements. Called also gutta-percha point.

cone of light the triangular reflection of light seen on the tympanic membrane.

pressure cone the area of compression exerted by a mass in the brain, as in transtentorial herniation.

retinal cone cone (def. 2).

silver cone silver point.

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cone

1. a solid figure or body having a circular base and tapering to a point, especially one of the conelike structures of the retina, which, with the retinal rods, form the light-sensitive elements of the retina. The cones make possible the perception of color.

2. in radiology, a conical or open-ended cylindrical structure used as an aid in producing high detail x-rays.

3. surgical cone.

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cone cells (1)

the commonest, if not the sole, photoreceptors in the central area of the retina, where the function of acute vision is located. See also cone (1) above.

cone down

in radiology, to restrict the x-ray beam. See also collimation.

cone dysplasia (1)

progressive dysplasia of retinal cones in Alaskan malamute dogs; causes impaired day vision from an early age. The rods are normal.

ether cone

a cone-shaped device used over the face in administration of ether for anesthesia.

cone flower

see rudbeckia.

cone of light

the triangular reflection of light seen on the tympanic membrane.

pressure cone

the area of compression exerted by a mass in the brain, as in transtentorial herniation.

retinal c's

see cone (1) above.

cone shellfish

see conus.