括約筋 (katsuyakukin: sphincter) to constrict + to shrink + muscle
The first kanji, 括 (KATSU, kuku(ru): to constrict), seems to break down as hand + tongue! What’s going on with that? Something about a hand-to-mouth existence?
Henshall says 舌 doesn’t actually mean “tongue” in this case. Rather, it’s an altered form of a shape that once meant “hollowed-out space.” In 括, the 舌 acts phonetically to express “to bind” and doesn’t necessarily contribute to the meaning. So 括 is either about binding the hands or binding something with the hands.
