chiasm


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chiasm

 [ki´azm]
a decussation or X-shaped crossing.
optic chiasm a structure in the forebrain formed by the decussation of fibers of the optic nerve from each half of each retina.

chi·asm

(kī'azm),
1. An intersection or crossing of two lines.
2. In anatomy, a decussation or crossing of two fibrous bundles, such as tendons, nerves, or tracts.
3. In cytogenetics, the site at which two homologous chromosomes make contact (thus appearing to be crossed), enabling the exchange of genetic material during the prophase stage of meiosis.
Synonym(s): chiasma [TA]
[G. chiasma]

chi·asm

(kīazm)
1. An intersection or crossing of two lines.
2. anatomy a decussation or crossing of two fibrous bundles, such as tendons, nerves, or tracts.
Synonym(s): chiasma.
3. cytogenetics the site at which two homologous chromosomes make contact (thus appearing to be crossed), enabling the exchange of genetic material during the prophase stage of meiosis.
Synonym(s): Budd syndrome.
[G. chiasma]

chi·asm

, chiasma (kīazm, kī-azmă)
In anatomy, decussation or crossing of two fibrous bundles, such as tendons, nerves, or tracts.
[G. chiasma]
References in periodicals archive ?
Additionally and concurrent with rotatory visual pathway shift, there is depression of the optic chiasm relative to the diaphragma sella line.
(b) Imaging one month later with T1-weighted MRI demonstrating a 22.0 x 12.0 mm bilobed mass with 8 mm suprasellar extension exerting mass effect on overlying optic chiasm.
In the present study, we demonstrate that CRMP4 is critical for the proper direction of retinal axons in the chiasm. Knocking down CRMP4 causes retinal axons to misproject to the ipsilateral side of the brain.
From autopsy findings in acute demyelinating disease, the spinal cord and optic chiasm reveal patches of demyelination and axonal degeneration associated with necrosis and cavitation.
He demonstrated that contrast material tracked proximally along the nerve to the optic chiasm, ultimately reaching the pons and midbrain.
(c) Coronal T2 weighted image demonstrates the mass abutting the lateral margin of the third ventricle and the superior margin of the optic chiasm (red arrow).
Half-field pattern reversal that is used for localization of lesions behind the optic chiasm has reduced clinical application in modern imaging procedures [1].
This suggests microglial activation in both eyes upon unilateral optic nerve damage, pointing towards cross-talk between both eyes, which may be orchestrated via the optic chiasm or hematogenous transference [53, 55].
The MR imaging of this patient revealed a macroadenoma with a size of 3x3.5x3 cm compressing the left optic nevre and the optic chiasm on the left side.
Emotions are likely not humanoid and wearing trousers and getting in physical conflicts with one another behind our optic chiasm. Memories we can no longer retrieve have likely not been shoved over the edge of a cerebral cliff by a bulldozer.
I then arrived at a 'stunning glimpse of the obvious': optometrists deal with conditions that go as far as the back of the eye; opthalmologists tend not to look beyond the optic chiasm; while occupational therapists deal with the whole spectrum, from the front of the eye to the back of the brain.