M+O 5 - proprioception Flashcards
What is proprioception?
awareness of position of body parts in relation to each other and surroundings
What is kinaesthesia?
movement awareness
What receptors are involved in proprioception?
- muscle spindles
- golgi tendon organs
- joint receptors
What 2 types of fibres are in muscles?
- extrafusal
- bulk of the muscle fibres
- contractile
- intrafusal
- muscle spindles
- specialised muscle fibres
- within a ct capsule
Where would you find the intrafusal muscle fibres?
within the extrafusal fibres
What are the majority of muscle fibres?
extrafusal
What portion(s) of the intrafusal fibres are contractile?
the end portions
- central portion is non-contractile, it can be stretched
What are the afferents of the intrafusal fibres activated by?
activated by stretch
What are the 2 types of nerve endings in the intrafusal fibres?
- secondary (flower-spray) nerve endings
- primary annuli-spiral nerve endings
What do secondary (flower-spray) nerve endings detect?
length of fibres
What do primary annulo-spiral nerve endings detect?
length of fibres and speed of change of length
What kind of neurones are the efferent nerves of the intrafusal fibres?
gamma motor neurones
What kind of neurones are the afferent nerves of the intrafusal fibres?
A alpha afferent
What type of neurone supplies the extrafusal fibres?
alpha motor neurone
What happens to spindle activity when muscle is stretched?
spindle activity increases
What is the role of muscle spindles?
- information about muscle length
- act to maintain muscle length
- load compensation
Where do the afferent neurones of the intrafusal fibres synapse?
synapse directly with nerve that causes the muscle to contract, causing muscle to contract and bring it back to where it was before
Where are the masticatory muscle spindle cell bodies?
trigeminal mesencephalic nucleus
Where do masticatory muscle spindle afferents synpase?
- in V motor nucleus and
- other areas linked to sensorimotor regulation:
- cerebellum
- cerebral cortex
What happens to muscle spindles if the muscle shortens (contracts)?
spindle collapses if loses tension and won’t work
What maintains spindle tension so they don’t collapse?
gamma motor neurones
What do gamma motor neurones cause contraction of?
the ends of intrafusal fibres
- maintain tension in spindle
- maintain spindle afferent activity
- alpha-gamma co-activation
What happens to the muscles and spindles during alpha-gamma co-activation?
- muscle shortens (alphas)
- spindle tension maintained (gammas)
- spindle activity maintained (gammas)
What happens to the muscles and spindles during load compensation/ resistance when biting?
- muscle doesn’t shorten
- gamma activity stretches spindle
- spindle activity increased
- alpha drive to muscle increases
