Nuclear bag fiber
Intrafusal muscle fiber / From Wikipedia, the free encyclopedia
A nuclear bag fiber is a type of intrafusal muscle fiber that lies in the center of a muscle spindle.[1] Each has many nuclei concentrated in bags and they cause excitation of the primary sensory fibers.[2]
This article relies largely or entirely on a single source. (October 2020) |
Quick Facts Details, Identifiers ...
Nuclear bag fiber | |
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Details | |
Identifiers | |
Latin | myofibra sacculiformis |
TH | H3.03.00.0.00013 |
Anatomical terms of microanatomy |
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There are two kinds of bag fibers based upon contraction speed and motor innervation.
- BAG2 fibers are the largest. They have no striations in middle region and swell to enclose nuclei, hence their name.
- BAG1 fibers, smaller than BAG2.
Both bag types extend beyond the spindle capsule.
These sense dynamic length of the muscle. They are sensitive to length and velocity.