筋 is a Japanese kanji written with 12 strokes, listed here under the keyword “muscle”. It is built from 竹 (bamboo) and 肋 (rib). In Remembering the Kanji by James W. Heisig it is frame 1012.
On KumiJi Glyph Explorer, open the parts search and type “bamboo” + “rib”. 筋 is among the results, together with every other character containing the same shapes.
Open 筋 in the interactive kanji search
to expand every part down to its smallest pieces, add your own names and mnemonic stories,
or search for other characters by their parts.