What are muscle spindles?

Muscle spindles are sensorimotor organs located in the skeletal muscle. Each muscle spindle consists of three to five specialized muscle cells known as intraphuse cells . These cells associated with the connective tissue sheath lay next to the rest of the skeletal muscle fibers. When intrafusion cells detect muscle length, reflexively stimulate muscle contraction to prevent excessive stretching and damage to muscle fibers. This is known as Stretch Reflex and is most often illustrated by a classic reflective test for a knee click performed during physical tests.

intrafusal cells are similar to structures to standard or extrafusal muscle cells. Both are long, roughly cylindrical cells consisting mainly of saromers. It differs in the fact that the center of the intrafusion cell lacks a contractile element of myosin in its center, so that the contraction occurs only at the ends. The passive central area is packed in specialized nerve endingsand flower spray. These nerve endings enter muscle spindles and branches within intrafusal cells, wrap each cell in a spiral arrangement, or extends to the surface of the fibers like spray flowers.

When the ends of intrafusion cells are withdrawn, or when the muscle abdomen itself is prolonged, it creates a passive section in the center of the muscle spindles. The nerve endings detect this section and signal motor neurons of neighboring extrafusal muscle fibers to download. After contraction, muscle fibers are shortened and a section of muscle spindles stops. This causes muscle spindles to end the contraction signal and release the muscles.

During physical tests, the doctor tests reflex stretching as an indicator of the overall functioning of the nervous system. The well -known knocking on the knee briefly pulls to the patellar tendon, the cord of connective tissue tklobouk runs from the four -headed muscle to the tibia just below the knee. That passIt stretches the muscle fibers of the thighs and activates the stretch response from the intrafus fibers inside the quadrilateral muscle. The fiber stretching stimulates the reflexive contraction of the same muscle, resulting in a small kick associated with the test.

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knee test or test patellar tendons acts as a sampling of the nervous system as a whole. Doctors can assess various nerve and muscle systems by testing the stretch reflex. This includes the functioning of motor neurons, inhibitory or excitation effects from higher levels of the nervous system and the efficiency of muscle spindles, as well as activation of the muscles themselves. Testing the performance of one reflex helps doctors in finding tracks in terms of the presence of various disorders of the central or peripheral nervous system.