rachis
Học thuậtThân thiện
Definition
- Noun:
- The series of vertebrae forming the axis of the skeleton and protecting the spinal cord; the spine or backbone. This is the primary anatomical meaning, referring to the central supporting column of a vertebrate.
- The axis or central stem of a compound leaf or a compound inflorescence (a flower cluster). This is a botanical meaning, referring to the main stem from which leaflets or flowers arise.
Usage Examples
Anatomical Meaning:
- The injury affected several vertebrae along the rachis.
- In birds, the rachis is the central shaft of a feather.
Botanical Meaning:
- The leaflets are arranged on either side of a long rachis.
- The botanist examined the rachis of the fern frond.
Advanced Usage
In Zoology/Ornithology: The term is often used specifically to describe the hollow, central shaft of a contour feather, to which the vanes are attached.
- The primary flight feather's strength depends on its rachis.
In Paleontology: Used to describe the fossilized spinal column of ancient vertebrates.
- The fossil's remarkably preserved rachis provided new insights.
Variants and Related Words
- Rachial (adj): Pertaining to the spine or rachis.
- Rachidian (adj): Another term meaning spinal or relating to the rachis.
- Rachilla (n): In botany, a secondary axis, especially the axis of a spikelet in grasses.
Synonyms
- Spine: The vertebral column.
- Backbone: The spine, especially as a symbol of strength or resolve.
- Vertebral column: The technical term for the series of vertebrae.
- Axis: The central line of a structure (more general, used in the botanical sense).
Related Phrases/Compounds
- Rachis length: A common measurement in botany and biology.
- Rachis fracture: A medical term for a break in the spinal column.
Notes on Meaning
The word rachis is a technical term used primarily in scientific contexts (anatomy, zoology, botany). Its meaning is highly specific and context-dependent. In everyday language, "spine" or "backbone" is used for the anatomical structure, and "stem" or "central stalk" is often used for the botanical structure.
Noun
- the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
- the fall broke his back
- axis of a compound leaf or compound inflorescence