Main Page | See live article | Alphabetical index A motor unit is a group of cells under the control of a motor neuron; groups of motor units work together, as a single muscle. The number of cells within each unit can vary: thigh muscles can have a thousand cells in each unit, eye muscles might have ten. See also: motor unit recruitment, contractile summation, tetanic contraction, zootomy This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.