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Flashcards in Proprioception Deck (17)

What are proprioceptors?

Mechanoreceptors that signal body or limb position


Give three examples of proprioceptors

Muscle spindles- monitor muscle length and rate of change of muscle length - control reflexes and voluntary movements
Golgi tendon organs - monitor tension on muscles
Joint receptors - Monitor joint angle, rate of angular movement, and tension on the joint


Which proprioceptors are involved with sending sensory information for spinal cord reflexes?

Golgi tendon organs and muscle spindles


What is a muscle spindle?

Intrafusal fibres with special sensory and motor innervation contained within a capsule, they lie in parallel with extrafusal muscle fibres


What are the two different types of intrafusal fibre?

Nuclear bag fibres - bag shaped, nuclei are all grouped together
Nuclear chain fibres - nuclei are lined up in a chain


What is contained at the ends of the muscle spindle?



What do gamma motoneurones innervate?

Innervate ends of intrafusal fibres which contract


What do alpha motoneurones innervate?

The extrafusal muscle fibres, they are larger than gamma motoneurones


How are regenerative action potentials in the muscle spindles created?

Muscle stretch stimulates the stretch receptors, stretch sensitive ion channel opens causing local generator potential - causing regenerative action potentials


Stretch receptors can monitor the rate of change of muscle length, how is this done

The rate of action potential formation reflects the velocity of change of muscle length


How is muscle length determined by the muscle stretch receptors?

The resting rate of action potential formation at one muscle length will be different to the resting rate of action potential formation at another length


How can spindle discharge be increased?

Stretching the agonnist


Describe the structure of the golgi tendon organ

Nerve endings mingle with tendon bundles at the end of the muscle


How are golgi tendon organs activated?

Contraction of the muscle, passive stretch doesn't affect them much


Are GTO's in series of parallel with the muscle?



Which proprioceptors are activated during isometric contraction?

Only GTO's since tension is increased but length of the muscle is kept constant


What is the purpose of gamma motor neurones?

Makes the intrafusal muscle contract in time with the extrafusal muscle, this restores sensitivity of the central part of the intrafusal fibres at a new muscle length - maintains spindle sensitivity