PROPRIOCEPTORS Flashcards
What does the muscle spindle detect?
Muscle length
What is the structure of the muscle spindle?
Small sensory organs enclosed in a capsule. They have contractile proteins (thick and thin filaments) at either end. The central region is wrapped by sensory dendrites.
They are found in parallel with extrafusal fibres.
What MN innervates the muscle spindle?
Gamma MNs
What is the benefit of the alpha-gamma coactivation?
It keeps the central region on the muscle spindle taut and responsive.
(When extrafusal fibres have been stimulated to contract by alpha MN activation, the gamma MN is also activated. The gamma MN stimulates contraction in the two ends of the intrafusal fibre readjusting the length keeping it taut and responsive)
When is the muscle spindle afferent activated, during muscle stretch or during muscle contraction?
Muscle Stretch
When is the gamma MN activated, during muscle stretch or muscle contraction?
muscle stretch (gamma MN innervate muscle spindle which detects muscle length)
When is the Golgi tendon organ afferent activated, during muscle stretch or muscle contraction?
Muscle contraction (golgi tendon measures muscle tension)
Activation of the gamma MN causes muscle contraction: true or false?
False. The gamma MN activates contraction of the intrafusal fibers, which do not produce enough force to have any effect on the muscle as a whole.
It is the alpha MNs that innervate the typical muscle fibers (extrafusal fibers) that produce contractions. Because of alpha-gamma coactivation, activation of the gamma motor neuron will occur at the same time as contraction of the muscle (but it doesn’t cause the contraction).
Where is the golgi tendon located?
In the tendons (attach bone to muscle), the sensory dendrites are interwoven with collagen fibrils.
What does the golgi tendon provide information on?
Muscle tension
