So I'm trying to describe someone loosening up their neck, you know, when they tilt their head to the side and kind of roll it around? My dude is getting ready to go into battle, for some background. Anyway, does this description work for that action? "He squared his shoulders and rolled his head around his neck, loosening up." You know, this in case I was unclear.
I'd suggest it doesn't work, makes it sound like head and neck are no longer connected. I've gone with head tilt to either side, stretching the neck until the satisfying click of vertebrae realigning into position. Neck roll works better than head roll, unless there's a guillotine nearby.
Honestly, I'd just skip it. That's one of those visual cues that works in movies but not so much in literature. The context of the scene will already illustrate that the character is heading into battle and whatnot, so you'd be edging into the redundant at that point. And it's one of those things that requires more words to describe than it's worth probably worth. I'm not saying it can't be effective, but I've gotten into trouble trying to do movie things in print.
He switched back and forth on the balls of his feet, with a nervous energy that switched to his neck. He was envisioning the fight, getting his body ready for action, or possibly death. You just need to ad enough visuals to make it part of the story.