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.
moÂ·tor. 1. In anatomy and physiology, denoting neural structures, that because of the impulses generated and transmitted by them, cause muscle fibers or pigment cells to contract or glands to secrete. See also: motor cortex, motor endplate, motor neuron.2. the entity consisting of the lower motor neuron, motor end-plate, and muscle fibers supplied by the end-plate. The final motor activity resulting from a sequence of stimulations to the lower motor neuron is considered a function of the motor unit.