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