Determine the muscles that power the ability to hold that position.

Description
Example: the upper extremities in the anatomical position are along the trunk lateral sides with the elbows extended and forearms supinated.

Repeat the above until you have each pose fully described in the static position.

Then determine the muscles that power the ability to hold that position. This is best done by assuming the pose yourself hold and feel the muscles at work.

Next move from pose #1 to pose #2 and describe the actions and planes, axis and muscles that do the work to get from #1 to #2.