Meaning & use
chiasm
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Meanings
nouncountablemedicaltechnical
A place where two nerves or structures cross each other, especially the optic chiasm where fibers from the eyes meet.
Grammar: Countable: an optic chiasm.
Patterns
- the optic chiasm
- a chiasm in something
Nerve fibers from both eyes cross at the optic chiasm.
A tumor pressing on the chiasm can affect vision.
The surgeon located the chiasm before operating.
nouncountablebiologytechnical
A point at which paired chromosomes touch and exchange material during cell division.
Grammar: Usually written chiasma in biology; the plural is chiasmata.
Patterns
- a chiasm forms
A chiasm forms where chromatids cross during meiosis.
Students counted each chiasm under the microscope.
Word forms
| plural | chiasms |
|---|
Common combinations
- optic chiasm
- The optic chiasm sits just below the brain.
- compress the chiasm
- A growth can compress the chiasm and blur vision.
- cross at the chiasm
- Visual signals cross at the chiasm.
- chiasm syndrome
- A rare chiasm syndrome affected his sight.
Synonyms and how they differ
- crossing
- Crossing is the plain word, while chiasm names a particular crossing in the body.
- chiasma
- Chiasma is the more common form in biology texts and has the plural chiasmata.
- decussation
- Decussation is a technical word for a crossing of nerve fibers, usually within the brain.
Word family
Commonly confused: chiasm or chiasmus?
chiasm vs chiasmus
Chiasmus is a figure of speech with reversed phrase order, while chiasm is a crossing in the body.
Practice
Where do nerve fibers from the two eyes cross each other?
Choose one answer.
The optic chiasm is where fibers from the eyes cross. The other places are unrelated to vision.
Make it your own
Write a sentence using “chiasm”, then check it and compare it with the examples above.