neurilemma
C1/C2Highly technical/scientific
Definition
Meaning
The outer sheath or membrane surrounding a peripheral nerve fiber (axon).
In neuroanatomy, it is a specialized structure, also known as the sheath of Schwann, that provides insulation and support to nerve axons. It plays a crucial role in the regeneration of damaged peripheral nerves.
Linguistics
Semantic Notes
Primarily used in anatomy, neurology, and medical contexts. The term is often used interchangeably with 'neurolemma' and specifically refers to the plasma membrane of a Schwann cell, which envelops the axon.
Dialectal Variation
British vs American Usage
Differences
No significant difference in usage or meaning. The spelling is consistent.
Connotations
Purely scientific/medical in both variants.
Frequency
Extremely low frequency in general discourse, but standard in relevant technical fields in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
The [axon] is surrounded by a [neurilemma].Damage to the [neurilemma] impairs [nerve function].Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Not used.
Academic
Core term in medical, biological, and neuroscience textbooks and research papers.
Everyday
Virtually never used.
Technical
Essential terminology in neurology, histology, and related surgical or clinical fields.
Examples
By Part of Speech
adjective
British English
- The neurilemmal sheath was clearly visible under the microscope.
American English
- Neurilemmal repair is critical for nerve regeneration.
Examples
By CEFR Level
- The doctor explained that the neurilemma helps protect the nerve.
- Injury can damage the neurilemma surrounding the nerve fibres.
- The regenerative capacity of peripheral nerves is largely dependent on an intact neurilemma.
- Histological examination revealed proliferation of Schwann cells within the neurilemma.
Learning
Memory Aids
Mnemonic
Think: 'NEURon' + 'LEMMA' (like a lemma in mathematics is a helper theorem). The NEURILEMMA is the 'helper sheath' for the neuron.
Conceptual Metaphor
A protective insulating sleeve or casing for a nerve wire.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid confusing with 'нейролемма' (direct equivalent) and 'миелиновая оболочка' (myelin sheath, which is a layer *within* the neurilemma). The neurilemma is the outermost cell membrane.
Common Mistakes
- Misspelling as 'neurolemma' (acceptable variant) or 'neuralemma'.
- Confusing it with the endometrium or perineurium (other nerve sheaths).
- Using it in non-scientific contexts.
Practice
Quiz
What is the primary function of the neurilemma?
FAQ
Frequently Asked Questions
No. The myelin sheath is a fatty insulating layer *inside* the neurilemma. The neurilemma is the outermost plasma membrane of the Schwann cell that also encloses the myelin sheath.
Exclusively in peripheral nerves (outside the brain and spinal cord). Central nervous system axons are not ensheathed by neurilemmas.
Damage can impair nerve signal conduction and hinder the nerve's ability to regenerate, potentially leading to loss of function or sensation.
The structure is closely associated with Theodor Schwann (1810-1882), a founder of cell theory, hence the synonym 'sheath of Schwann'.