Do you think it's even possible to describe the body skill...the "how it's being done?" I mean, the way I see it, there's the left-brained-type (abstract modeling) of conceptualizing the series of events which constitute aiki waza and then there's the right-brained-type (spacial interaction) of sensing and performing the skills themselves. Thinking about how things are moving within the body (left-brained/physical mechanics description) serves as a guide for where to place the awareness so one can then sense and learn how to purposefully engage those skills in the space of reality.
There's also the cerebellum, a part of the brain that takes care of translating the request signals of the conscious brain into the complex patterns/signals to all the various muscle groups that need to fire in harmony for nearly all of out macroscopic movements. This is also why knowing exactly which muscle you need to fire is almost useless unless you have trained the cerebellum to fire that muscle exclusively.
For kicks and giggles sometime, try tightening the muscles of the forearm/wrist and shoulder while relaxing the muscles around the elbow. It's entirely possible to do, but until your cerebellum figures it out, you can wish all you want to do this seemingly simple task. When you try to relax your arm above the elbow, I guarantee you'll relax the muscles of the shoulder and wrist, at least if this is the first time you've tried this.
Intellectualization is great, but words are words.