The Gamma Loop System

The muscle spindle not only serves as a feedback system to the alpha motor neuron, but has within it a separate feedback system of its own called the gamma loop system. This system operates to maintain tension on the intrafusal muscle fibers. To provide information about static or changing muscle length, the annulospiral ring must be under some minimal amount of tension; otherwise, the stretch-sensitive channels remain closed, and no action potentials are generated. A correction for this potential problem is achieved through motor innervation of the small intrafusal muscle fibers themselves, specifically near the ends of the fiber, so that a minimum amount of tension can be maintained on the fibers within the capsule at all times (Fig. 2). The motor neurons innervating the muscle spindle fibers are not the large

Ia afferents from annulospiral stretch receptors

Ia afferents from annulospiral stretch receptors

a motor neurons to extrafusal muscles

FIGURE 2 Innervation of the muscle spindle by gamma motor neurons. As gamma motor neurons become active, they cause greater contraction of intrafusal fibers and greater stretching of the annulospiral ring. This increased tension on the ring makes it more sensitive to any further change in length caused by contraction or stretching of the extrafusal muscle fibers. Less activity in the gamma motor neurons decreases the sensitivity of the annulospiral ring. Upper motor neurons, most of which have fibers in the corticospinal tract, can control activity in both alpha and gamma motor neurons.

a motor neurons to extrafusal muscles

FIGURE 2 Innervation of the muscle spindle by gamma motor neurons. As gamma motor neurons become active, they cause greater contraction of intrafusal fibers and greater stretching of the annulospiral ring. This increased tension on the ring makes it more sensitive to any further change in length caused by contraction or stretching of the extrafusal muscle fibers. Less activity in the gamma motor neurons decreases the sensitivity of the annulospiral ring. Upper motor neurons, most of which have fibers in the corticospinal tract, can control activity in both alpha and gamma motor neurons.

alpha motor neurons that innervate the main muscle mass but a different set of smaller cells, the gamma motor neurons. The role of the gamma system is to allow the spindle to maintain high sensitivity over a wide range of muscle lengths during contraction and relaxation. Like alpha motor neurons, the gamma motor neurons are located within the ventral horn of the spinal cord; they also receive substantial input from higher motor centers. A number of descending pathways indirectly influence motor activity through control of the drive on the gamma loop system, thus making muscles more or less susceptible to myotactic reflex responses.

Get Rid of Gallstones Naturally

Get Rid of Gallstones Naturally

One of the main home remedies that you need to follow to prevent gallstones is a healthy lifestyle. You need to maintain a healthy body weight to prevent gallstones. The following are the best home remedies that will help you to treat and prevent gallstones.

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