背中

1. Origins, structure, and basic meaning

• Structure: 背中 is a noun read せなか for the back of the torso.
• Basic usage: It identifies the back as a body surface, such as where one sweats or what a child clings to.
  • In 坂道を歩いていると背中に汗をかいた。, the speaker's back becomes sweaty while walking on a slope; in 子どもは父の背中にしっかりつかまった。, the child holds tightly to the father's back.

2. Common pitfalls and similar expressions

• Location marked by に
  • In 背中に汗をかく, に marks the body area where the sweat appears.
• 父の背中につかまる
  • の identifies whose back it is, while に marks what the child clings to.
• 背中 and 腰
  • 背中 broadly denotes the back of the torso, while 腰(こし) focuses on the waist or lower-back area. Keep the body regions distinct.