Why is there bamboo in 筋?

Question

Why does 筋 have bamboo at the top part? Surely tendons and muscles are related to flesh 肉 and strength 力, and even looks a bit like muscle 肌, but I can't seem to find a reason why there is bamboo 竹 on top as it doesn't seem to contribute phonetically or semantically. Is it purely a decorative component to distinguish from 肋/肌?

Answer 1

Ji Xusheng's, A New Textual Research on Origin of Chinese Characters, p. 351 has the following entry:

Here it is shown that the original meaning was:

释义：竹筋

This is further referenced and translated in Outlier's Dictionary of Chinese Characters:

In 筋, 𥫗 “bamboo leaves hanging down; bamboo” is a  meaning component, pointing to the  original meaning “bamboo sinew.”

The extension of meanings from there is then fairly logical. See Outlier's meaning tree:

1 (orig.) bamboo sinew
2 → tendon
3 → muscle fiber
‎‎‏‏‎ ‎‏‏‎ ‎‏‏‎ ‎‏‏‎ ‎4 ⇒ muscle

Answer 2

Why does 筋 have bamboo at the top part?

To distinguish ribs, bone, from actual meat, which is muscles and tendons.

Mostly, bones and flesh come together.

筋骨：jīngǔ：physique
肋骨 lèi gǔ ：rib(s)
筋：jīn,qián：muscles; tendons
肋： lèi,lē,jīn：ribs; chest
肉：⺼：ròu,rù：ribs
力：lì：power, capability, influence
竹：zhú：bamboo （2个）

Imagine you are an ancient Chinaman. You want to represent meat with a little ideograph. What would you draw? A blob? But if you represent meat with bone, the task becomes easier: ⺼. Actually draw the bones and the infer the meat attached thereto, the poor pig split asunder!

肋骨骨折 fractured rib （ouch)

Answer 3

Let's trace the root word of 筋:

【集韻】筋，古文竻字。註見六畫。

竻 《康熙字典》- 【集韻】歷德切，音勒。竹根也。

Bamboo Roots: