chiasm

Thân thiện

The optic chiasm is a crucial structure in the brain where the optic nerves cross.

Definition

1. Noun:
   • A crossing or intersection of two structures, especially nerves or tracts, in the shape of the letter X: In anatomy and biology, a chiasm is the point where two parts, such as optic nerves, cross over each other, forming an X-shaped structure.
   • A rhetorical or literary structure involving the inversion of the order of words in parallel phrases: In rhetoric and literature, a chiasm (or chiasmus) is a figure of speech where the second part of a phrase is syntactically balanced against the first, but with the parts reversed (e.g., "Do not live to eat, but eat to live").

Usage Examples

• Noun (Anatomical):
  • The optic chiasm is a critical structure where nerve fibers from each eye partially cross.
  • Damage to the chiasm can result in specific visual field deficits.
• Noun (Rhetorical):
  • The poet used a chiasm to create a memorable and balanced phrase.
  • "Ask not what your country can do for you—ask what you can do for your country" is a famous example of a chiasm.

Advanced Usage

• "chiasmal" or "chiasmic" (adjective): Pertaining to or resembling a chiasm.
  • The surgeon studied the chiasmal region before the operation.
• "chiasmatically" (adverb): In a manner involving or relating to a chiasm.
  • The clauses were arranged chiasmatically for rhetorical effect.

Variants and Related Words

• Chiasma: A variant spelling, often used interchangeably with "chiasm," particularly in genetics to describe the point where chromatids cross over during meiosis.
  • Genetic recombination occurs at the chiasma.
• Chiasmus: The specific term for the rhetorical device. While "chiasm" can be used in this context, "chiasmus" is more precise.
  • The speech was full of clever chiasmus.

Synonyms

• Crossing: The point where two things intersect (general/anatomical).
• Decussation: A more technical anatomical term for a crossing, especially of nerve fibers, in the form of an X.
• Inversion: A reversal of position, order, or relationship (rhetorical).

Related Phrases

• Optic chiasm: The specific anatomical structure where the two optic nerves cross.
  • The tumor was located near the optic chiasm.
• Form a chiasm: To create or constitute such a crossing or rhetorical structure.
  • These neural tracts form a chiasm at the base of the brain.

Related Idioms

(Note: "Chiasm" itself is a technical term and is not commonly used in idiomatic expressions. However, the concept is central to specific fields.) - Chiasmic structure: A term used in literary criticism to describe a work or passage built around this inverted parallelism. - The entire sonnet has a chiasmic structure, mirroring themes in the first and last quatrains.

Học thuật

Noun

1. an intersection or crossing of two tracts in the form of the letter X

Từ đồng nghĩa

• chiasma
• decussation