proprioception Flashcards
what is the meaning of proprioception ?
sense of relative position of neighbouring parts of the body
what does modern evidence suggest about joint capsules? (2)
good for injury prevention
people with hip replacements still have good sense of joint placement despite new joint
describe characteristics of a muscle spindle
bundle of fibres in a capsule
parallel with main extrafusal
wrapped around sensory axons
gamma neurons cause contraction of spindle
alpha neurones innervate the muscle
what do the sensory axons do in terms of the muscle spindle
detect the stretch
detects mechanical deformation
what’s meant by intrafusal and extrafusal ?
intra - sindle itself
extra - main body of muscle
what does the muscle spindle detect ? (2)
static length of muscle - position
rate of change of muscle stretch - velocity
position + velocity
what happens when length of muscle fibre changes in muscle spindles ?
mechanical deformation of axons
opens ion channels
changes membrane potential and firing rate of axon
what are primary endings in the muscle spindle ? (3)
signal position and velocity
transmitted via 1a afferents
sensitive to vibrations
what are secondary endings in the muscle spindle ? (2)
control position only
transmitted via group 2 afferents
what are gamma fibres in the muscle spindle ? (3)
contractile element of spindle
no useful force output
keep spindle taught
what is alpha- gamma coactivation ?? (2)
maintains sensitivity of spindle in the face of changing the muscle length
helps keep taut to be sensitive and stop slack
what happens during alpha gamma coactivation ? (4)
1a spindle afferent continuously fires to signal muscle length
contraction of muscle causes spindle to slacken
this reduces firing rate and loss of sensitivity
gamma activation keep spindle taut
how does vibration effect muscles ?
activates 1a afferents
creates illusion of muscle stretch - position and velocity illusions
explain characteristics of the Golgi tendon organ (3)
indirectly contributes to rotation sense - signals force + heaviness
in series w muscle
on interface w tendon and muscle
what is a difference between golgi organ tendon and muscle spindle ?
(GTO) records tension compared to recording length (MS)
why is golgi tendon rogan useful when muscle movement is ambiguous ?
helps brain realise how force is being used
e.g. concentric vs eccentric movement in muscles can indicate why body is swaying
if the GTO and MS where artificially stimulated what is the main difference when the muscle contracts ?
MS goes quiet due to slack
GTO shows increased firing rate
when conducting experiments into why proprioception is useful, what did they find ?
testing sensory thresholds help detects which sense is more important
proprioception can allow you to keep boy upright using just your ankles
why is interaction with vestibular system important ?
allows connect of head orientation
proprioception using neck muscles help with head orientation
what was found about age and proprioception ?
no strong link between falls and proprioception
ankle proprioception declines with ages
why is peripheral neuropathy associated with falls ?
blow blood flow from e.g. diabetes can reduce sensation in limbs which can lead to falls
what was found in research about postural sway w eyes open and eyes closed? (3)
people say more with eyes closed
disproportional increase in sway in weaker people - can’t use proprioceptive sense
stronger muscles help w proprioception
