释义 |
optic chiasma
optic chiasman. A structure in the brain formed by the partial intersection or crossing of the optic nerve fibers on the underside of the hypothalamus. Also called optic chiasm.op′tic chias′ma (or chi′asm), n. a site at the base of the forebrain where the inner half of the fibers of the left and right optic nerves cross to the opposite side of the brain. [1870–75] ThesaurusNoun | 1. | optic chiasma - the crossing of the optic nerves from the two eyes at the base of the brainchiasma opticum, optic chiasmchiasm, chiasma, decussation - an intersection or crossing of two tracts in the form of the letter X |
optic chiasma
optic chiasma[′äp·tik kī′az·mə] (neuroscience) The partial decussation of the optic nerves on the undersurface of the hypothalamus. optic chiasma
optic chiasman. A structure in the brain formed by the partial intersection or crossing of the optic nerve fibers on the underside of the hypothalamus. Also called optic chiasm.optic chiasma The junction of the two OPTIC NERVES lying under the brain. In the chiasma optic nerve fibres from the inner half of each RETINA cross over. Those from the outer half do not. Thus fibres from the inner half of each retina run out of the chiasma in close association with fibres from the outer half of the retina on the other side. The two optic tracts so formed run into the brain. This arrangement ensures that input to both eyes from the right field of vision causes signals that pass to the left half of the brain, and vice versa.optic chiasma a point under the hypothalamus of the brain where the two optic nerves meet and cross over, so that stimuli from each eye are interpreted in the OPTIC LOBE of the opposite side of the brain.chiasma, optic A structure located above the pituitary gland and formed by the junction and partial decussation (crossing-over) of the optic nerves. The fibres from the nasal half of the retina of the left eye cross over to join the fibres from the temporal half of the right retina to make up the right optic tract and vice versa. About 53% of the axons of the optic nerves cross to the opposite tract (Fig. C9). A lesion of the chiasma produces a typical field defect (heteronymous hemianopia). Note: also spelt chiasm. See circle of Willis; decussation; visual pathway; stereo-blindness; optic tracts." >Fig. C9 An illustration of the decussation of the optic nerve fibres occurring in the optic chiasmaoptic chiasma Related to optic chiasma: corpus callosum, optic tractSynonyms for optic chiasmanoun the crossing of the optic nerves from the two eyes at the base of the brainSynonyms- chiasma opticum
- optic chiasm
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