It is worth thinking about without obsessing, if you are just riding to work on your Raleigh 'all steel' then the advice given above is what you need, on the other hand a little thought might help prevent injury or help deal with one when it arrives.
The items on your list (knees feet and thighs) are mechanical or skeletal parts of your body and cannot move unassisted, although 'thighs' is vague and you may mean the muscles. It is the muscles that are the movers and knowing what muscles move the knees may help with your enquiry, the legs move from the hips and what muscles do this may also help, the same with the ankles. One part of the leg plays a bigger part than the others when engaging in a variety of speed terrain etc but this comes automatically and most people don't think about it.
If considering these things increases your enjoyment of riding I say go for it.