Usually when I'm practicing, I'm not mindlessly doodling because I'm actively trying to improve or refine my skills or knowledge of the human body. With these sketches, I was focusing mainly on the connection between arm and torso, as well as the connection between arm and forearm.
I think most artists are familiar with enough anatomical knowledge to use shorthand techniques to imply certain features. However, with these drawings I wanted to push myself and see how much I could indicate without going overboard and still make it an aesthetically pleasing sketch.
What's interesting is that even if I'm looking at parts of a photo or an anatomical diagram, I still need to edit and articulate that information in my drawing with respect to my pose. Sometimes just a line will do, other times, a combination of lines or even broken lines are necessary. So far, it's been fun trying to figure out WHAT lines will communicate which muscles are doing what.
I've been keeping up with my New Year's goal so far, I just have way too many sketches to scan than I have time to scan them. Hopefully I'll do a massive post soon and just get them up here. Until then, hope you enjoy!