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.
A motor neuron, sometimes combined into the singular term motoneuron, is a nerve cell. Its basic structure includes a receptor on one end and a transmitter on the other, connected by an elongated body called the axon, some of which can be 39 inches (1m) long in humans.