括約筋

1. Origins, structure, and basic meaning

• Structure: 括約筋, read かつやくきん, is a sphincter muscle that encircles an opening or passage and controls it by tightening and relaxing.
• Basic usage: Its function may be studied in anatomy, and its position can be identified on a digestive-system model.

2. Common pitfalls and similar expressions

• An anatomical muscle that closes a passage
  • This is the anatomical name of a muscle whose function is explained with a model or whose location is identified around digestive organs. It is not a symptom or the name of the whole organ.