Nuclear chain fiber

Nuclear chain fiber
Nuclear chain fiber
	A muscle spindle, with γ motor and Ia sensory fibers
Details
Part of	Muscle spindle
Identifiers
Latin	myofibra catenaformis
TH	H3.03.00.0.00014
	Anatomical terms of microanatomy [edit on Wikidata]

A nuclear chain fiber is a specialized

organ contained within a muscle. Nuclear chain fibers are intrafusal fibers that, along with nuclear bag fibers, make up the muscle spindle

There are 3–9 nuclear chain fibers per muscle spindle that are half the size of the

The secondary nerve association involves an efferent and afferent pathway that measure the stress and strain placed on the muscle (usually the extrafusal fibers connected from the muscle portion to a bone). The afferent pathway resembles a spring wrapping around the nuclear chain fiber and connecting to one of its ends away from the bone. Again, depending on the stress and strain the muscles sustains, this afferent and efferent coordination will measure the "stretch of the spring" and communicate the results to the central nervous system.

A similar structure attaching one end to muscle and the other end to a tendon is known as a

nuclear bag fibers in that they are considered in series rather than in parallel

Innervation

As

static γ motor neurons. Stimulation of γ neurons causes the nuclear chain to shorten along with the extrafusal muscle fibers

v t e Sensory receptors
Touch	Mechanoreceptor Vibration Lamellar corpuscle Light touch Tactile corpuscle Pressure Merkel nerve ending Stretch Bulbous corpuscle
Pain	Free nerve ending Nociceptors
Temperature	Thermoreceptors
Proprioception	Golgi organ Muscle spindle Intrafusal muscle fiber Nuclear chain fiber Nuclear bag fiber
Other	Hair cells Baroreceptor