Each skeletal muscle fiber is innervated by a single motor axon. The same axon may also innervate other muscle fibers. All the fibers innervated by the same axon are called a motor unit.
In this "color coded" image, the green bands are motor axons labelled with yellow fluorescent protein. Red along the edges of the axon terminals shows the location of acetylcholine receptors in the muscle membrane. (Muscle striations reveal the scale of this image, approximately 2µm per sarcomere.) (Image courtesy Jeff Lichtman, used with permission.) |
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Last updated: 13 August 2021 / dgk