Innervated muscle structure involved in reflex actions and proprioception
For the class of neurons characterized by a large spindle-shaped body, see Spindle neuron.
Muscle spindle
Mammalian muscle spindle showing typical position in a muscle (left), neuronal connections in spinal cord (middle) and expanded schematic (right). The spindle is a stretch receptor with its own motor supply consisting of several intrafusal muscle fibres. The sensory endings of a primary (group Ia) afferent and a secondary (group II) afferent coil around the non-contractile central portions of the intrafusal fibres. Gamma motor neurons activate the intrafusal muscle fibres, changing the resting firing rate and stretch-sensitivity of the afferents. [a]
Details
Part of
Muscle
System
Musculoskeletal
Identifiers
Latin
fusus neuromuscularis
MeSH
D009470
TH
H3.11.06.0.00018
FMA
83607
Anatomical terminology
[edit on Wikidata]
Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed by the brain as proprioception. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, for example, by activating motor neurons via the stretch reflex to resist muscle stretch.
The muscle spindle has both sensory and motor components.
Sensory information conveyed by primary type Ia sensory fibers which spiral around muscle fibres within the spindle, and secondary type II sensory fibers
Activation of muscle fibres within the spindle by up to a dozen gamma motor neurons and to a lesser extent by one or two beta motor neurons[citation needed]
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Musclespindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length...
muscles. However, their role is important in keeping musclespindles taut, thereby allowing the continued firing of alpha neurons, leading to muscle contraction...
make spindlesSpindle apparatus or mitotic spindle, a cellular structure in cell biology Musclespindle, stretch receptors within the body of a muscle Spindle...
of a stretch receptor called the musclespindle found in muscles, which constantly monitors the rate at which a muscle stretch changes. The information...
length (group II neurons). These two types of sensory neurons compose musclespindles. There is a similar division of encoding in invertebrates; different...
length of a muscle. They constitute the musclespindle, and are innervated by both sensory (afferent) and motor (efferent) fibers. Intrafusal muscle fibers...
generators (CPGs). At the base level, sensory input is relayed by musclespindles in the muscle and Golgi tendon organs (GTOs) in tendons, alongside cutaneous...
intrafusal muscle fibers thereby controlling musclespindle sensitivity. On examination a diminished resistance to passive movement will be noted and muscles may...
muscle length or velocity. It can also include a polysynaptic component, as in the tonic stretch reflex. When a muscle lengthens, the musclespindle is...
sensory fiber terminals within the musclespindle. Although delayed onset muscle soreness is a symptom associated with muscle damage, its magnitude does not...
the muscle called musclespindles. Each musclespindle consists of sensory nerve endings wrapped around special muscle fibers called intrafusal muscle fibers...
contained within a muscle. Nuclear chain fibers are intrafusal fibers that, along with nuclear bag fibers, make up the musclespindle responsible for the...
Golgi organ Musclespindle, sensory receptors within the belly of a muscle, which primarily detect changes in the length of this muscle Pulmonary stretch...
the motor root of the trigeminal nerve and terminate in the musclespindles in the muscles of mastication. They are proprioceptive fibers, conveying information...
fibers of the alternative classification system, and are the fibers from musclespindle endings and the Golgi tendon, respectively. Type Aβ fibres, and type...
muscle reflexes (patellar reflex, achilles reflex), brief stimulation to the musclespindle results in contraction of the agonist or effector muscle....
The multifidus (multifidus spinae; pl.: multifidi) muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side...
(CNS). Musclespindles are thought to be the main type of mechanoreceptor responsible for proprioceptive attributes from the ankle. The musclespindle gives...
neurons innervate intrafusal muscle fibers found within the musclespindle. They regulate the sensitivity of the spindle to muscle stretching. With activation...
A nuclear bag fiber is a type of intrafusal muscle fiber that lies in the center of a musclespindle. Each has many nuclei concentrated in bags and they...
of muscles into muscle compartments. Two types of sensory receptors found in muscles are musclespindles, and Golgi tendon organs. Musclespindles are...
excitability of musclespindles, and decreased synaptic inhibition. These consequences result in abnormally increased muscle tone of symptomatic muscles. Some authors...
example, a specific muscle fiber called an intrafusal muscle fiber is a type of afferent neuron that lies parallel to the extrafusal muscle fibers thus functions...
with a muscle. In contrast to musclespindles, which are sensitive to changes in muscle length, tendon organs detect and respond to changes in muscle tension...
resistance offered by the muscle is directly proportional to velocity of the passive movement. It is caused by increased musclespindle excitability and velocity...
doi:10.1038/nbt.3297. PMID 26237517. S2CID 21241434. "Chapter 1: The MuscleSpindle and the Central Nervous System". Neuromuscular Reeducation with Electromyometric...
Spindle cell sarcoma is a type of connective tissue cancer. The tumors generally begin in layers of connective tissue, as found under the skin, between...