神経

1. Origins, structure, and basic meaning

• Structure: 神経 (しんけい) is a noun for bodily nerves and, figuratively, mental attention spent on fine details.
• Basic usage: 歯の神経に触れる identifies bodily tissue painfully touched by something cold, while 音に神経を使う describes excessive mental attention to small sounds.

2. Common pitfalls and similar expressions

• Anatomical nerve and mental vigilance
  • 歯の神経 is anatomical, whereas 神経を使う is an idiom for exercising care and attention. The latter does not physically consume nerve tissue.