/ic/ - Artwork/Critique

So I'm trying to learn anatomy and, as a first step, how to build the skeleton in 3D. Proko's lessons are great but holy shit the spine is kicking my ass. I feel like most of the battle is just getting the ribcage and pelvis blocked in while properly visualizing the flow of the spine in 3D space.

I've read enough Robertson to know how to approach such things technically, if I need to project a curve into a well-defined cube or plane or whatever I can do it. But a tube fluidly curving and flowing through space at all sorts of angles is a different beast. Is there some exercise or technique that helps visualize this sort of thing intuitively?

The ribcage is the worst because I know it's rigid, but I swear it really can look like it bends or twists or whatever