筋
すじ · suji · JLPT N3 · noun
string
💪🧵 筋 = bamboo 竹 + flesh ⺼ + power 力: long fibres that pull, like muscle
Flesh ⺼ plus power 力 gives muscle, and bamboo 竹 adds its long fibres. From sinew the meaning extends to any line or thread: 筋書き (sujigaki) is a story's plot line, and 筋肉 (kinniku) is muscle.
筋 — bamboo 竹 + flesh 月(肉) + strength 力
A semantic compound: 月 (flesh) shows it relates to the body, 力 (strength) hints at muscular force, and 竹 (bamboo) suggests fibers like bamboo strands. Together they depict the sinews or tendons that give the body its strength.