This is another one of the 'self-challenges' that I used to do to improve my poor skills.
My target here was to paint anatomy from memory but involving possibly some aspect that I never painted before.
So I've started this hunting at down scene with naked massive torso...from back....and black!
(Dudes, render that skin it was a pain, but really instructive and amusing)

Finished in about two days and obviously without references at all, so I bet you'll find some 'spare' muscle here and there LOL

Crits are always welcome (and please, forgive my english)