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September 17, 2021

Muscle Fiber Spindle

Muscle fiber spindle, nerve fibers

Toluidine blue-stained thick section prepared from glutaraldehyde-fixed EPON embedded tissue (400x original magnification)

muscle fiber spindle, Function of Muscle Fiber Spindle

What of the following single choices regarding this structure is false?

A. Generates contraction

B. Senses muscle stretch

C. Common in muscle

D. Part of myotatic reflex


Answer: Generates contraction

The muscle fiber spindle detects length and rate of muscle stretch, is the most frequently found sense organ in skeletal muscle, and is part of the deep tendon reflex (monosynaptic stretch reflex/myotatic reflex).

It does not contribute significantly to the force of muscle contraction.


Banks RW. The innervation of the muscle spindle: a personal history. J Anat. 2015 Aug;227(2):115-35. doi: 10.1111/joa.12297. Epub 2015 Jun 19. PMID: 26095428; PMCID: PMC4523316.

Kröger S, Watkins B. Muscle spindle function in healthy and diseased muscle. Skelet Muscle. 2021 Jan 7;11(1):3. doi: 10.1186/s13395-020-00258-x. PMID: 33407830; PMCID: PMC7788844.

Thornell LE, Carlsson L, Eriksson PO, Liu JX, Österlund C, Stål P, Pedrosa-Domellöf F. Fibre typing of intrafusal fibres. J Anat. 2015 Aug;227(2):136-56. doi: 10.1111/joa.12338. PMID: 26179023; PMCID: PMC4523317.

Walkowski AD, Munakomi S. Monosynaptic Reflex. 2021 Feb 8. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 31082072.