Are action potentials used to control voluntary muscle contractions?

I always learn about the term action potential in relation to reflexes (i.e. your hand is on a hot stove and you must move it using your muscles). Are action potentials also the means of transmission of nerve impulses that control voluntary muscle contraction (i.e. walking) or sensation detection on the skin or even the contraction of some involuntary muscles (i.e. the heart and digestive tract)?