Extrafusal muscle fibers
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Extrafusal_muscle_fibers".

Extrafusal muscle fibers are a class of muscle fiber innervated by alpha motor neurons.

They generate tension, do mechanical work and allow for movement by contracting.

Compare with intrafusal muscle fiber - is of sensory type and innervated by gamma motor neurons.

Extrafusal muscle fibers and associated alpha motor neurons are called a motor unit. The connection between alpha motor neuron and extrafusal muscle fiber is a neuromuscular junction, and the neurotransmitter responsible for contraction is acetylcholine.

External links

• Cartoon of intrafusal vs. extrafusal fibers

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