Optic chiasm

Encyclopedia : O : OP : OPT : Optic chiasm

Gray's Fig. 773 - The left optic nerve and the optic tracts.

Gray's FIG. 722– Scheme showing central connections of the optic nerves and optic tracts.

The optic chiasm (Greek χίασμα, "crossing", from the Greek χλαζειν 'to mark with an X', after the Greek letter 'Χ', chi) is the part of the brain where the optic nerves partially cross. Specifically, the nerves connected to the right eye that attend to the right visual field cross with the nerves from the left eye that attend to the left visual field. The parts of both eyes that attend to the right visual field are processed in the left visual system in the brain, and vice versa.

In Siamese cats with certain genotypes of the albino gene, this wiring is disrupted, with less of the nerve-crossing than is normal, as a number of scholars have reported. ([OMIA]) To compensate for lack of crossing in their brains, they cross their eyes (strabismus.) This is also seen in albino tigers, as Guillery & Kaas report.

References

R. W. Guillery; J. H. Kaas. Genetic Abnormality of the Visual Pathways in a "White" Tiger. Science. 1973 Jun 22;180(92):1287-9. [GS]

Guillery, R. Visual pathways in albinos. Scientific American 1974 May;230(5):44-54. [PubMed]

Sensory system - Visual system - [http://encycl.opentopia.com/ edit]
Eye > Optic nerve | Optic chiasm | Optic tract | Lateral geniculate nucleus | Optic radiation | Visual cortex

Diencephalon - [http://encycl.opentopia.com/ edit]

third ventricle, interventricular foramina, optic chiasm, subfornical organ epithalamus: pineal body, habenula, habenular nuclei anterior hypothalamus: paraventricular nucleus, supraoptic nucleus, suprachiasmatic nucleus intermediate/middle/tuberal hypothalamus: infundibulum, median eminence, arcuate nucleus, ventromedial nucleus pituitary gland: anterior pituitary, posterior pituitary posterior hypothalamus: posterior nucleus, mammillary body subthalamus: subthalamic nucleus thalamus: pulvinar,medial geniculate nucleus, lateral geniculate nucleus, list of thalamic nuclei

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.