Sensory coding of muscles (365/351) Flashcards
what types of intrafusal fibres do primary afferents wrap around
all types - commonly nuclear bag type
what does the muscle spindle primary ending include
primary afferent and the intrafusal fibres it wraps around
what type of intrafusal fibres do secondary afferents attach to
nuclear chain type - with flower spray endings
what does the muscle spindle secondary ending include
secondary afferent and the intrafusal fibres it contacts
is nuclear bag type 1 or 2 more dynamic
1 = more dynamic
what do larger muscle stretches lead to
larger receptor potentials
(more stretch = more ion flow)
what does the firing rate (AP/s) of muscle spindles most closely correspond to
changes in length of muscle
how does the CNS receive a sensory input proportional to the length of muscle
difference in firing rate between the initial and final length of the muscle
how does the CNS receive a sensory input proportional to the velocity of muscle stretch
difference in firing rate of muscle spindles during the dynamic phase of muscle stretch
do primary or secondary endings have a higher dynamic index
primary endings
which phase of movement are primary endings more sensitive to
dynamic phase - velocity of muscle stretching
which phase of movement are secondary endings more sensitive to
muscle length (NOT velocity)
when are firing rates in primary endings high
when stretch increases
(low firing rate during holds and releases)
when are firing rates in secondary endings high
during stretch holds
(low during dynamic / changing phases)
why are muscle spindles so important for proprioception
most important source of sensory info used to perceive limb position and movement
