Week 2-2 Flashcards
divergence
a single neuron synapses on multiple neuron
convergence
multiple neuron converge on fewer neurons (alpha motor neron)
extrafusal
skeletal
intrafusal
muscle spindles
afferent
to the CNS
efferent
away from the CNS
where is the cell body located
dorsal root ganglion
sensory afferent labeling
afferent are labels based on cross sectional diameter I largest IV smallest
what does conduction depend on
diameter
larger diameter =
faster conduction
Group 1a (primary)
muscle spindles
length and velocity
Group II
length or (static length of the muscle)
do muscle spindles lie in parallel or series the the skeletal muscle
parallel
what is the shape of a muscle fiber
football (fusiform shaped)
why do hand muscle have a higher density of spindles?
the hands are important for fine motor task and we dont know what length and where the muscle are in space
bag 1
dynamic (length change of the muscle
bag 2
static (coding for the static length)
chain
static (coding for the static length)
afferent type 1A
primary (length and velocity of stretch)
innervate bag 1,2 and chain
type II
secondary static length
innervates bag 2 and chain
la primary send info from
all muscle spindles rectors
II secondary send info from
static receptors (bag 2 and chain)
how do we record?
microneurigraphy (single unit action potential with needle)
what happens when the stretch gets quicker
the action potential get closer together (Ia are firing faster)
plateaus in the middle
have a faster firing rate because of the length tension relationship
as the length of the muscle decreases the
AP rate also decreases
what does the tendon tap activate
primaries Ia they are very sensitive to vibration and taps and can stop firing on release
what is the efferent system of the motor neuron called
gamma system
E alpha motor neurons send info to
extrafusal muscle fibers (skeletal)
E gamma motor neurons send info to
muscle spindles
dynamic gamma sends info to
Bag 1
static gamma sends info to
bag 2 and chain
why do we have the gamma motor system
maintains sensitive of the spindle when there is slack in the muscle and prevents the spindle from coming unloaded
gamma dynamic makes the spindle
more velocity sensitive
gamma static makes the spindle
more length sensitive
co activation
alpha and gamma are at the same time
without co activation
the muscle would become unloaded so it will not fire while it is shortened
