Normally, the coordinated action of the muscles of the stomach and small intestine propels the food from the stomach, through the small intestine and into the colon. This muscular action also sweeps bacteria out of the small intestine and limits the numbers of bacteria in the small intestine.
The term 'motor neuron' is usually restricted to the efferent neurons that actually innervate muscles (the lower motor neurons). A single motor neuron may innervate many muscle fibres and a muscle fibre can undergo many action potentials in the time taken for a single muscle twitch.
The function of a motor neuron is to carry an electrical signal to a muscle, triggering it to either contract or relax. In vertebrate animals, including humans, movement of the articulated internal skeletal structure is enabled by coordinating the contractions of the many muscles attached to it.