retinal cone

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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retinal cone

n.

See cone cell.

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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.