膝小僧

1. Origins, structure, and basic meaning

• Structure: 膝小僧(ひざこぞう) denotes the rounded front of the knee.
• Basic usage: It describes scraping the front of the knee in a fall.
  • 転んで膝小僧をすりむいてしまった。

2. Common pitfalls and similar expressions

• Scope compared with 膝
  • 膝(ひざ) broadly refers to the knee. 膝小僧 is a familiar expression specifically for its protruding front.