Muscles muscle spindles. Medical search. Frequent questions

Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. (wikipedia.org)
Although desmoid tumors can arise in any skeletal muscle, they most commonly develop in the anterior abdominal wall and shoulder girdle. (medscape.com)
Although desmoid tumors most commonly arise from the rectus abdominis muscle in postpartum women and in scars due to abdominal surgery, they may arise in any skeletal muscle. (medscape.com)
Skeletal muscles are the largest cells in the body and are one of the few syncytial ones. (frontiersin.org)
Recently, two independent models, one from rodents and the other from insects, have demonstrated that nuclei are not lost from skeletal muscle fibers when they undergo either atrophy or programmed cell death. (frontiersin.org)
Skeletal muscle is the largest tissue in the body. (frontiersin.org)
Skeletal muscle is fairly unique in that the mature cells are syncytial and can contain hundreds of nuclei. (frontiersin.org)
Alpha a motor neurons of which stimulation of a single nerve fibre excites from 3 to 2000 skeletal muscle fibres which we call the motor unit. (positivehealth.com)
Gamma c motor neurons, which transmit impulses to special skeletal muscle fibres, called intrafusal fibres, part of the muscle spindle. (positivehealth.com)
Each muscle spindle is built around 3-10 small intrafusal muscle fibres attached to the sheaths of the surrounding extrafusal skeletal muscle fibres, the ends of which are excited by small gamma efferent motor nerve fibres. (positivehealth.com)
The muscles establish a tensile three-dimensional grid for the balanced support and movement of the skeletal structure by providing the elastic forces that move the bones through space. (bodymindcentering.com)
It has been my unique focus to study the mechanics of skeletal muscles, not in isolation but in their in vivo context. (vu.nl)
The goal is to improve our understanding of the changes in neural control of movement and secondary changes in skeletal muscle properties in response to a stroke. (vu.nl)
Proximal esophagus is skeletal muscle. (memory.com)

The muscle spindle has both sensory and motor components. (wikipedia.org)
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] Muscle spindles are found within the belly of a skeletal muscle. (wikipedia.org)
Primary type Ia sensory fibers (large diameter) spiral around all intrafusal muscle fibres, ending near the middle of each fibre. (wikipedia.org)
Fusimotor neurons are classified as static or dynamic according to the type of muscle fibers they innervate and their effects on the responses of the Ia and II sensory neurons innervating the central, non-contractile part of the muscle spindle. (wikipedia.org)
they make synapses at either or both of the ends of the intrafusal muscle fibers and regulate the sensitivity of the sensory afferents, which are located in the non-contractile central (equatorial) region. (wikipedia.org)
When a muscle is stretched, primary type Ia sensory fibers of the muscle spindle respond to both changes in muscle length and velocity and transmit this activity to the spinal cord in the form of changes in the rate of action potentials. (wikipedia.org)
Likewise, secondary type II sensory fibers respond to muscle length changes (but with a smaller velocity-sensitive component) and transmit this signal to the spinal cord. (wikipedia.org)
The function of the gamma motor neurons is not to supplement the force of muscle contraction provided by the extrafusal fibers, but to modify the sensitivity of the muscle spindle sensory afferents to stretch. (wikipedia.org)
Deletion of GDNF expression from muscle spindles results in the selective elimination of γ-MNs with preservation of the spindle and its sensory innervation. (biomedcentral.com)
But a small number of large sensory fibres from the muscle spindles terminate directly on the anterior motor neurons. (positivehealth.com)
Sensory fibres originate in this area and are stimulated by stretch of this mid-portion of the spindle. (positivehealth.com)
Muscle spindles emit sensory nerve impulses all the time when they are stretched the rate of firing increases, when they are shortened the rate of firing decreases. (positivehealth.com)
Currently, he studies the sensory encoding of mechanical interactions between neighboring muscles, the neuromechanical consequences of stroke and hemophilic arthropathy, the structure-function relationship and mechanobiology of tendons, and effects of muscle stretching using prosthetic devices in children with cerebral palsy. (vu.nl)

Muscle spindles are fusiform (spindle-shaped), and the specialized fibers that make up the muscle spindle are called intrafusal muscle fibers. (wikipedia.org)
The superior oblique is a fusiform (spindle-shaped) muscle belonging to the extraocular group of muscles. (healthline.com)

The regular muscle fibers outside of the spindle are called extrafusal muscle fibers. (wikipedia.org)
Muscle spindles have a capsule of connective tissue, and run parallel to the extrafusal muscle fibers. (wikipedia.org)
Muscle spindles are composed of 5-14 muscle fibers, of which there are three types: dynamic nuclear bag fibers (bag1 fibers), static nuclear bag fibers (bag2 fibers), and nuclear chain fibers. (wikipedia.org)
Activation of the neurons causes a contraction and stiffening of the end parts of the muscle spindle muscle fibers. (wikipedia.org)
The dynamic axons innervate the bag1 intrafusal muscle fibers. (wikipedia.org)
The reflexly evoked activity in the alpha motor neurons is then transmitted via their efferent axons to the extrafusal fibers of the muscle, which generate force and thereby resist the stretch. (wikipedia.org)
Upon release of acetylcholine by the active gamma motor neuron, the end portions of the intrafusal muscle fibers contract, thus elongating the non-contractile central portions (see "fusimotor action" schematic below). (wikipedia.org)
Gamma motor neurons (γ-MNs) selectively innervate muscle spindle intrafusal fibers and regulate their sensitivity to stretch. (biomedcentral.com)
They constitute a distinct subpopulation that differs in morphology, physiology and connectivity from α-MNs, which innervate extrafusal muscle fibers and exert force. (biomedcentral.com)
Fusimotor axons originate either from gamma motor neurons (γ-MNs), which only innervate intrafusal fibers of the muscle spindle, or from alpha motor neurons (α-MNs), which innervate extrafusal muscle and also send a β-skeletofusimotor collateral axon to innervate the muscle spindle [ 2 - 4 ]. (biomedcentral.com)
The advantages of a γ-fusimotor system to control spindle sensitivity independently of force-generating extrafusal muscle fibers are not fully understood, nor are the mechanisms that generate the distinct γ- and α-MN subtypes in mammals. (biomedcentral.com)
Local cold also has a direct effect on the conduction velocities of the afferent and efferent fibers, which further decreases muscle spasm. (medscape.com)
Muscle spindle fibers in the muscles communicate information to allow the muscles to maintain proper muscle tension to support the joints. (yang-sheng.com)
These nerve endings and muscle spindle fibers degenerate without regular use. (yang-sheng.com)
Within your muscle fibers, theirs an optimal length for force production. (scienceofrunning.com)
The anterior (ventral) horns of the "H" contain lower motor neurons, which receive impulses from the motor cortex via the descending corticospinal tracts and, at the local level, from internuncial neurons and afferent fibers from muscle spindles. (msdmanuals.com)

Muscle spindles provide proprioceptive information required for motor control. (biomedcentral.com)

The Ia afferent signals are transmitted monosynaptically to many alpha motor neurons of the receptor-bearing muscle. (wikipedia.org)
The Ia afferent signal is also transmitted polysynaptically through interneurons (Ia inhibitory interneurons), which inhibit alpha motorneurons of antagonist muscles, causing them to relax. (wikipedia.org)

Muscles and Tendons have an abundance of two special types of receptors. (positivehealth.com)
The somatosensory system may be thought of as having its beginnings in receptors located in the skin, joints, ligaments, muscles, and fascia. (medscape.com)

The receptor portion of the muscle spindle is located midway between its to ends where the intrafusal muscle fibres have no contractile element. (positivehealth.com)
This causes both the extrafusal & intrafusal muscle fibres to contract at the same time. (positivehealth.com)

They increase the firing rate of Ia and II afferents at a given muscle length (see schematic of fusimotor action below). (wikipedia.org)
This raises the resting potential of the endings, thereby increasing the probability of action potential firing, thus increasing the stretch-sensitivity of the muscle spindle afferents. (wikipedia.org)

This article provides insight into the importance of a voltage-gated sodium channel in proprioceptors, a group of mechanosensory neurons that target muscle. (elifesciences.org)
The embodied functions of proprioceptors (muscle spindles and Golgi tendon organs). (bodymindcentering.com)

The motor part of the spindle is provided by motor neurons: up to a dozen gamma motor neurons also known as fusimotor neurons. (wikipedia.org)
Gamma motor neurons supply only muscle fibres within the spindle, whereas beta motor neurons supply muscle fibres both within and outside of the spindle. (wikipedia.org)

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. (wikipedia.org)

There is a general agreement that hypertrophy is accompanied by the addition of new nuclei from stem cells to help the muscles meet the enhanced synthetic demands of a larger cell. (frontiersin.org)

Unlike other mechanoreceptors, the sensitivity of muscle spindles is actively regulated by a specialized fusimotor system. (biomedcentral.com)
This allows for continuous control of the mechanical sensitivity of spindles over the wide range of lengths and velocities that occur during normal motor behaviors [ 1 ]. (biomedcentral.com)
Phylogenetically, γ-MNs are best developed in mammals, whereas lower vertebrates (for example, amphibians) use a β-skeletofusimotor system alone to control the sensitivity of their muscle spindles. (biomedcentral.com)

They lie within the muscle tendons. (positivehealth.com)

They are tiny parts of each muscle fiber that takes information from nearby skin and joints to assist in communication with the control center, or the brain. (athletico.com)
This balance center works with your eyes, muscles, joints and brain to keep you upright even when you are turning your head to scan your environment. (athletico.com)
For instance, when the joints don't perceive relative motion, the muscle doesn't feel elongation. (athletesacceleration.com)

However, extraocular muscle function testing showed notable changes ( Fig. 1 ). (aao.org)

This information helps the brain know where your head and neck are located in space and can adjust muscle tightness in response to the information. (athletico.com)
Stretching exercises should not be instituted acutely because they may cause reactive paraspinal muscle spasm and tightness. (medscape.com)
Whether it be muscle or joint tightness or a combination of the two, we'll need to get this part of the body moving again. (athletesacceleration.com)

Immunostaining with vimentin, alpha smooth muscle actin, muscle actin, and desmin are helpful in distinguishing the tumors in the differential diagnosis of desmoid tumors. (medscape.com)
Embodying muscles and initiating movement at the molecular level (actin and myosin). (bodymindcentering.com)

These activate the muscle fibres within the spindle. (wikipedia.org)
An average of 10 -15 muscle fibres are usually connected with each Golgi Tendon Organ (GTO) which are stimulated by tension from the muscle fibres. (positivehealth.com)

Local application of cold causes vasoconstriction, lowers cell metabolism, decreases extensibility of collagen tissue, decreases muscle contractility, decreases nerve conduction velocity, and increases the pain threshold. (medscape.com)
Nociceptors for pain also appear to be "free nerve" endings in skin and muscle. (cdc.gov)

Therefore when a muscle is suddenly stretched a strong signal is transmitted to the spinal cord causing an instant v strong reflex contraction of the same muscle from which the signal originated. (positivehealth.com)
1. Golgi Tendon Organs that detect tension applied to the muscle tendon during muscle contraction/stretch. (positivehealth.com)
The posteffects are possibly dependent on the repeated voluntary contraction of leg and foot intrarotating pelvic muscles that rotate the trunk over the stance foot, a synergy common to both protocols. (hindawi.com)

The __________ __________ carries motor (__________) information to muscle and glands. (flashcardmachine.com)

Its function is manifested in the form of the muscle stretch reflex, which consists of static & dynamic reflexes. (positivehealth.com)
The dynamic stretch reflex is caused by the potent dynamic signal transmitted via the primary endings of the muscle spindles. (positivehealth.com)
With the dynamic stretch reflex over within a few a fraction of a second after the muscle has been stretched to its new length, a much weaker static reflex continues after for as long as the muscle is maintained at an excessive length. (positivehealth.com)
Thus this negative stretch reflex opposes the shortening of the muscle in the same way that the positive stretch reflex opposes lengthening of the muscle. (positivehealth.com)
Thus sudden stretch of muscle spindles is all that is required to elicit a stretch reflex. (positivehealth.com)

The aim is to assess to what extent the subtendons arising from each of the three triceps surae muscles act independently. (vu.nl)

We do know there are a lot more of these spindles in the neck contributing to balancing our big heads on our shoulders. (athletico.com)
These work together with your muscles to tell your brain where your head and neck are located in space, and they work a little more at the end ranges of your movements to provide more information. (athletico.com)
however, a mask and snorkel should be used to avoid aggravation of the cervical muscles that is encountered as the neck is rotated during breathing when swimming. (medscape.com)

Thus the major difference between the GTO and the muscle spindle is the spindle detects relative muscle length & the GTO detects muscle tension. (positivehealth.com)
If I knew exactly, I'd be a genius, but one thing that could play a role is muscle tension. (scienceofrunning.com)
One of the reasons is muscle tension. (scienceofrunning.com)
So, what is this mysterious muscle tension? (scienceofrunning.com)
We can get incredibly complex on explaining what resting muscle tension is and how it can be altered, but when we do that it loses it's practicality in application to the real world. (scienceofrunning.com)
With that in mind, here's the useful simplified way to look at muscle tension. (scienceofrunning.com)
Your body controls the resting tension through a variety of mechanisms, mainly through muscle spindles. (scienceofrunning.com)
Because these muscles have been in shortened state for a while the body adjusts the resting tension. (scienceofrunning.com)
That's muscle tension. (scienceofrunning.com)

When the receptor portion of the muscle spindle is stretched slowly, the number of impulses transmitted from both the primary & secondary endings increases virtually in proportion to the degree of stretch. (positivehealth.com)

We have our abdominal and lower back muscles in addition to the majority of our scapular muscles attaching to this area of the spine. (athletesacceleration.com)
11: Gunnarsson U, Stark B, Dahlstrand U, Strigård K. Correlation between abdominal rectus diastasis width and abdominal muscle strength. (cancercentrum.se)

Innovative muscle principles (proximal and distal initiation, muscle coupling and currenting, A and B muscles, four stages of a muscle action, eight functions of a muscle). (bodymindcentering.com)

Similarly these reflexes can be obtained from almost any muscle of the body by striking its tendon, i.e. eliciting a knee jerk. (positivehealth.com)
Aim is to investigate how different stretching protocols affect muscle morphology and joint, muscle and tendon mechanics in people with joint and muscle contractures of the extremities. (vu.nl)

With these markers of γ-MN identity, we show after conditional elimination of GDNF from muscle spindles that the survival of γ-MNs is selectively dependent on spindle-derived GDNF during the first 2 weeks of postnatal development. (biomedcentral.com)

Loss of muscle spindles also results in the downregulation of Gfrα1 expression in some large diameter MNs, suggesting that spindle-derived factors may also influence populations of α-MNs with β-skeletofusimotor collaterals. (biomedcentral.com)
However, since there are many different non-muscle cell populations that reside within the tissue, these experiments cannot easily distinguish true myonuclei from those of neighboring mononuclear cells. (frontiersin.org)

The first system is muscle spindles. (athletico.com)

1. Muscle spindles that detect change in muscle fibre length & rate of change in length. (positivehealth.com)
Following a change in the anatomy, length changes of the transffered muscle with joint movements are reversed compated to the normal case. (vu.nl)

Under the curved walking condition, the control of the muscle synergies takes into account not only the obligatory propulsion but also the equilibrium constraints connected to body rotation. (hindawi.com)
1987), y el Modelo de Control de Locomoción Visual (Lee & Lishman, 1977b) se integran en un solo modelo, que todavía incorpora desarrollos recientes en la investigación empírica. (bvsalud.org)

The trapezius muscle is innervated by nerves from which plexus? (brainscape.com)

This suggests that while a combination of Piezo2 and other Na V isoforms is sufficient to elicit activity in response to transient stimuli, Na V 1.1 is required for transmission of receptor potentials generated during sustained muscle stretch. (elifesciences.org)

GFP display structural and synaptic features of γ-MNs and are selectively lost in mutants lacking target muscle spindles. (biomedcentral.com)

Analyzing the actions of individual muscles and of groups of muscles from the perspective of one's position in relation to gravity. (bodymindcentering.com)

Interrelationships between muscles in different parts of the body and as they pass through different fascial planes. (bodymindcentering.com)

As well, many older individuals suffer from sarcopenia, a protracted muscle wasting disorder that typically begins after the age of 50 and involves a loss of about 1% of muscle mass per year ( Woo, 2017 ). (frontiersin.org)

When movement is negligible, muscles literally can't work to produce force. (athletesacceleration.com)

Hence, if no motion is happening at the thoracic spine, these powerful and important muscles can't contract to help provide mobility, stability, or power. (athletesacceleration.com)

Effects of low-load-prolonged-stretching on muscle properties and joint mobility. (vu.nl)

Desmoid tumors tend to infiltrate adjacent muscle bundles, frequently entrapping them and causing their degeneration. (medscape.com)

Taiji works many muscle groups to restore and improve function. (yang-sheng.com)

Anatomy74

Organisms10

Diseases9

Chemicals and Drugs27

Analytical, Diagnostic and Therapeutic Techniques and Equipment14

Psychiatry and Psychology5

Phenomena and Processes45

Disciplines and Occupations3

Anthropology, Education, Sociology and Social Phenomena1

Information Science4

Skeletal14

Sensory13

Fusiform2

Fibers16

Proprioceptive1

Afferent2

Receptors2

Intrafusal2

Afferents2

Proprioceptors2

Gamma2

Neurons1

Nuclei1

Sensitivity3

Tendons1

Joints3

Extraocular1

Tightness3

Actin2

Fibres2

Nerve2

Contraction3

Glands1

Stretch reflex5

Independently1

Neck3

Tension9

Secondary1

Abdominal2

Distal1

Tendon2

Conditional1

Populations2

System1

Length2

Control2

Plexus1

Potentials1

Target muscle1

Actions1

Parts1

Loss1

Movement1

Provide1

Mobility1

Degeneration1

Groups1