Help with posing

So I just rigged up my first model ever, and i’m starting to do an animation. However, when I pose, say, the whole left arm (including left hand, left arm, left shoulder) There is a sort of valley on the underside of the arm mesh where the middle vertexes get sucked in (i think - see picture). Is this a problem with how i rigged the bones? Please help, I’m eager to start animating. :slight_smile:


I am so sorry, I just realized that i posted this in the wrong place. Forgive me (and delete) as i will move it.