Where does everything originate in the operation of the human body?
In the human body, all operation originates in the brain and mind—the head. Paul uses this to illustrate that Christ is the head of the body, and the body receives its marching orders from Him, not from any denominational hierarchy, as He speaks through the Word.
Les explains from Ephesians 4 that Paul consistently uses the human body as an illustration. After warning against being children tossed to and fro by every wind of doctrine, Paul says that speaking the truth in love causes growth into Him who is the head, Christ. In the physical body, the fingers, legs, toes, and everything else operate from the brain, the mind, the head. So Christ is the head of the body, and as the body functions even in this world, its marching orders come from the head. They do not come from some denominational hierarchy. The head, Christ, speaks through the Word.