I've been working on my anatomy, focusing on the muscles of the shoulder and upper back this week.
Tintoretto says, "Nature is always the same, and therefore the muscles of the figures are not to be varied at whim." True words, sir! I actually see a lot of superhero drawings with intensively muscle-bound characters that seem to have more muscles than everyone else, and I've suspected that some of them are the invention of the artist. There's only one way to know for sure!