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.
Noun. 1. motor neuron-a neuron conducting impulses outwards from the brain or spinal cord. efferent neuron, motoneuron, motor nerve fiber. nerve cell, neuron-a cell that is specialized to conduct nerve impulses. efferent, efferent nerve, motor nerve-a nerve that conveys impulses toward or to muscles or glands.otor neuron. (or motoneuron) A nerve cell that carries messages from the central nervous system to a muscle or gland. See efferent.