<prompt> The number of muscle fibers innervated by a motor axon is smallest in:GastrocnemiusOrbicularis oculiSingle-unit smooth muscleSoleus  <response>: The extraocular and hand muscle has a ratio of 3-6 total 3000 motor units whereas gastrocnemius and back muscle concern with posture has a innervation ratio of 2000 total 600 units. 