Victor Forge
The Golgi tendon organ (GTO) is a sensory receptor organ that exists in the musculotendinous junction, where the muscle connects to the tendon, and the tendon connects to the bone. GTOs sense muscular tension within muscles when they contract or are stretched. When a GTO is stimulated, it causes its associated muscle to relax by interrupting its contraction. This process is called autogenic inhibition. When a muscle is stretched, the spindle around the intrafusal fiber sends an afferent signal to the spinal cord, stimulating the muscle to cause a stretch reflex, which will have an inhibitory effect on the antagonistic muscle being stretched. This is the opposite of the myotatic reflex (or stretch reflex), in which stretch elicits a reflex contraction.
| Characteristics | Values |
|---|---|
| GTO function | GTOs detect and respond to changes in muscle tension caused by muscular contraction, but not passive stretch. |
| GTO location | GTOs are located in the musculotendinous junctions. |
| GTO role | GTOs send information to the brain when they sense an overload. |
| GTO and muscle spindle | GTOs and muscle spindles work together reflexively to regulate muscle stiffness. |
| Muscle spindle function | Muscle spindles monitor muscle length and induce contraction to protect the muscle from tearing. |
| Muscle spindle location | Muscle spindles are wrapped around muscle fibres near the muscle belly. |
| Autogenic inhibition | When a GTO is stimulated, it causes its associated muscle to relax by interrupting its contraction. |
| Stretch reflex | When a muscle spindle is stretched, it causes a contraction to protect the muscle from being overstretched. |
| Myotatic reflex | The myotatic reflex is caused by a stretching in the muscle spindle, leading to a reflex contraction. |
| Muscle energy technique (MET) | A technique that uses a muscle's own energy in the form of gentle isometric contractions to relax and lengthen the muscle. |
| Proprioceptive neuromuscular facilitation (PNF) | A stretching practice that promotes the response of neuromuscular mechanisms through the stimulation of proprioceptors. |
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What You'll Learn
GTOs are nearly as common as muscle spindles
GTOs, or Golgi Tendon Organs, are nearly as common in most muscles as muscle spindles. They are proprioceptors that are located in the tendon adjacent to the myotendinous junction. In humans, some 10 to 20 muscle fibres are connected to one tendon organ.
GTOs and muscle spindles work together to help you stretch safely and effectively. When a GTO is stimulated, it causes its associated muscle to relax by interrupting its contraction. This process is called autogenic inhibition. The function of the GTO can be considered opposite to that of the muscle spindle, which serves to produce muscle contraction.
When a muscle is stretched, the muscle spindle is also stretched, causing it to lose its spiral shape. This signals the muscle to contract, which in turn protects the muscle from being overstretched. This process is called the stretch reflex.
GTOs are sensitive to changes in tension and rate of tension. They are responsible for sending information to the brain when they sense an overload. For example, when a low-force stretch is held for more than seven seconds, the increase in muscle tension activates the GTO, which temporarily inhibits muscle spindle activity, thus reducing tension in the muscle and allowing for further stretching. This is an important concept in muscle stretches, such as PNF and static stretching.
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GTOs detect muscle tension
GTOs, or Golgi Tendon Organs, are sensory organs that detect muscle tension. They are located in the musculotendinous junctions, where muscles connect to tendons, and tendons connect to bones. GTOs are nearly as common in muscles as muscle spindles, and they work together reflexively to regulate muscle stiffness.
When a muscle is stretched, the muscle spindle, which exists around the intrafusal fibre, sends an afferent signal to the spinal cord. This signal stimulates the muscle to cause a stretch reflex, which has an inhibitory effect on the antagonistic muscle that is being stretched. The greater the stretch, the greater the contraction from the muscle.
GTOs are activated when they are pinched by collagen during the stretching of a muscle and its connective tissue. This excites the afferent signal, which is sent to the spinal cord. The GTO then sends information to the brain when it senses an overload or excessive tension. This causes the muscle to relax, preventing it from being overstretched or torn. This reflex is called the inverse stretch reflex, or tendon reflex, and it operates as a negative feedback mechanism to control muscle tension.
The tendon reflex helps regulate muscle force and maintain steady levels of tension and stable joints. It can also override the stretch reflex when tension is great, for example, causing a person to drop a very heavy weight.
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GTOs send signals to the spinal cord
GTOs, or Golgi Tendon Organs, are sensory receptor organs that exist in the musculotendinous junction, where the muscle connects to the tendon, and the tendon connects to the bone. GTOs sense muscular tension within muscles when they contract or are stretched. They are sensitive to changes in tension and the rate of tension.
When the GTO is activated during contraction, it causes inhibition of the contraction, which is an automatic reflex called autogenic inhibition. When the GTO is activated during stretching, it inhibits muscle spindle activity within the working muscle so a deeper stretch can be achieved. This is also an automatic response.
GTOs are responsible for sending information to the brain as soon as they sense an overload. They also send force information to the spinal cord, where interneurons receive input from the brain that specifies the amount of force a muscle should produce. The Ib sensory fibres are sent through the dorsal root into the spinal cord to synapse on Ib inhibitory interneurons that, in turn, terminate directly on the motor neurons that innervate the same muscle. This causes a reflex inhibition of the muscle.
The GTOs' inhibitory effects are due to their reflex arcs. The tendon reflex operates as a negative feedback mechanism to control muscle tension and prevent too much tension on the muscle and tendon. The tendon reflex may help spread muscle load throughout the muscle fibres, thereby preventing damage to isolated fibres.
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GTOs can be stimulated by muscle contraction
GTOs, or Golgi Tendon Organs, are proprioceptors located in the tendons near the myotendinous junction. They are activated by stretch or active contraction of a muscle and transmit information about muscle tension. GTOs are nearly as common in most muscles as muscle spindles.
When GTOs are stimulated by muscle contraction, they cause the associated muscle to relax by interrupting its contraction. This process is called autogenic inhibition. GTOs are sensitive to changes in tension and rate of tension. They send information to the brain as soon as they sense an overload. For example, when lifting weights, the GTO tells how much tension the muscle is exerting. If there is too much tension, the GTO will inhibit the muscle from creating any force, thus protecting against injury.
Muscle contraction straightens the collagen fibres surrounding the GTO and compresses and depolarises the sensory ending. Ib axons are fast-conducting (72-120 m/s) and send branches rostrally and caudally via the dorsal columns. They then innervate premotor interneurons, causing a reflex inhibition of the muscle.
GTOs and muscle spindles work together reflexively to regulate muscle stiffness and prevent injury. Muscle spindles are considered to be the opposite of GTOs as they serve to produce muscle contraction. When a muscle is stretched, it pulls on the spindle, causing it to stretch as well. This signals the muscle to contract, protecting it from being overstretched.
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GTOs can be stimulated by stretching
GTOs, or Golgi Tendon Organs, are sensory receptor organs that exist in the musculotendinous junction, where the muscle connects to the tendon, and the tendon connects to the bone. GTOs are important proprioceptors that play a role in flexibility and work together with muscle spindles to regulate muscle stiffness.
When GTOs are stimulated by stretching, they cause the stretched muscle to relax, which is the opposite of the myotatic reflex, where stretch elicits a reflex contraction. This reflex, called the inverse stretch reflex, connects high force in the GTOs with relaxation. When a muscle is stretched, the GTO is pinched by collagen, exciting the afferent signal sent to the spinal cord. This signal activates the GTO, which then inhibits muscle spindle activity within the working muscle, allowing a deeper stretch to be achieved.
Static stretching is an example of how muscle tension signals a GTO response. When a low-force stretch is held for more than seven seconds, the increase in muscle tension activates the GTO, which temporarily inhibits muscle spindle activity, thereby reducing tension in the muscle and allowing for further stretching. This process is known as autogenic inhibition, where the GTO causes its associated muscle to relax by interrupting its contraction.
GTOs are also important in preventing injury by detecting and responding to changes in muscle tension. If a muscle is put under excessive tension, the GTOs are excited, and the deep tendon reflex is activated, causing the muscles to relax and protecting them from being overstretched or torn. This reflex arc is a negative feedback mechanism that prevents too much tension on the muscle and tendon.
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Frequently asked questions
GTO stands for Golgi Tendon Organ, a sensory receptor organ that exists in the musculotendinous junction.
GTOs sense muscular tension within muscles when they contract or are stretched. When the GTO is activated during contraction, it causes inhibition of the contraction, which is an automatic reflex. When the GTO is activated during stretching, it inhibits muscle spindle activity within the working muscle so a deeper stretch can be achieved.
The purpose of the GTO is to detect tension and potentially send inhibitory information to the motor neuron that innervates the muscle. This helps prevent injury by enabling a muscle to respond to increases in tension.
Muscle spindles are sensitive to changes in muscle length, whereas GTOs detect and respond to changes in muscle tension caused by muscular contraction but not passive stretch.
When a muscle is stretched, the GTO is pinched by collagen and this excites the afferent signal, which is sent to the spinal cord. This is how the GTO is activated. When the GTO is activated during stretching, it inhibits muscle spindle activity within the working muscle so a deeper stretch can be achieved.
