Extrafusal muscle fiber

Extrafusal muscle fiber
Details
Part of Skeletal muscle
Identifiers
Latin myofibra extrafusalis
TH H3.03.00.0.00007
Anatomical terminology

Extrafusal muscle fibers are the skeletal standard muscle fibers that are innervated by alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement. They make up the large mass of skeletal muscle tissue and are attached to bone by fibrous tissue extensions (tendons).

Each alpha motor neuron and the extrafusal muscle fibers innervated by it make up a motor unit.[1] The connection between the alpha motor neuron and the extrafusal muscle fiber is a neuromuscular junction, where the neuron's signal, the action potential, is transduced to the muscle fiber by the neurotransmitter acetylcholine.

Extrafusal muscle fibers are not to be confused with intrafusal muscle fibers, which are innervated by sensory nerve endings in central noncontractile parts and by gamma motor neurons in contractile ends and thus serve as a sensory proprioceptor.

Extrafusal muscle fibers can be generated in vitro (in a dish) from pluripotent stem cells through directed differentiation.[2] This allows study of their formation and physiology.

See also

References

  1. ↑ Purves, Dale (2011). Neuroscience (5th ed.). Sunderland, Mass.: Sinauer. pp. 355–358. ISBN 978-0-87893-695-3.
  2. ↑ Chal J, Oginuma M, Al Tanoury Z, Gobert B, Sumara O, Hick A, Bousson F, Zidouni Y, Mursch C, Moncuquet P, Tassy O, Vincent S, Miyanari A, Bera A, Garnier JM, Guevara G, Hestin M, Kennedy L, Hayashi S, Drayton B, Cherrier T, Gayraud-Morel B, Gussoni E, Relaix F, Tajbakhsh S, Pourquié O (August 2015). "Differentiation of pluripotent stem cells to muscle fiber to model Duchenne muscular dystrophy". Nature Biotechnology. 33: 962–9. doi:10.1038/nbt.3297. PMID 26237517.
  • "Chapter 1: The Muscle Spindle and the Central Nervous System". Neuromuscular Reeducation with Electromyometric Feedback (PDF). Advanced Therapy Institute. Retrieved 30 November 2013.
  • Smith, RS; Ovalle, Jr, WK (October 1973). "Varieties of fast and slow extrafusal muscle fibres in amphibian hind limb muscles". J. Anat. 116 (Pt 1): 1–24. PMC 1271546. PMID 4273105.


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