I see all these of anatomical drawings in ppl's sketchbooks. Some of them show joints that are partially mechanical to show how they work... Where are they drawing these from? Hopefully, it's an online source..
If memory serves you also see plenty such drawings in Bammes' book. I never could make head or tails of Bridgman - the drawings aren't detailed enough to be useful, at least to me.
My sketchbook thread: