Yes, today we have a word for muscle - in mandarin it's ji rou - ji means "flesh"; rou means "meat". Of course, there are anatomical names for individual muscles too now, same as in western medicine oviously, since they have western medicine doctors in China. But in ancient times, there was no specific word for muscle. If you really want to research this seriously, I suggest you examine The Expressiveness of the Body, and the Divergence of Greek and Chinese Medicine by Shigehisa Kuriyama, but I warn you that this is a fairly scholarly work, not an easy read at all. I've only looked at it in a most cursory manner.