neuro lab reflexes Flashcards
where are muscle spindles located
located deep w/in the muscle belly
what do muscle spindles detect
sensitive to stretch or change in muscle length
what is the significance of muscle spindles in the jerk response
when muscle is stretched the muscles spindles are also stretched hence activating Ia fibers in the spindle
these fibers synapse directly with the efferent motor neuron in SC there by eliciting a contraction in response to stretch stimulus
stretch in muscle spindle = contraction of same muscle
what do GTO detect
degree of tension or the contraction of a muscle
what is the significance of GTO
if tension is too high it will trigger Ib fibers of the GTO to send signal received by the inhibitory interneuron in the SC which synapses c efferent motor neuron causing the muscle to relax
tension in muscle = relaxation of muscle
what is the structure of an intrafusal m fiber
central (dilated) - non contractile portion
polar ends - contractile portion
what is the structure of the central portion
has 2 large myelinated afferent nerve fibers
Ia - annulospiral
II - flowerspray
what does the Ia fibers detect
static and dynamic stretch bcs present in both nuclear bag and nuclear chain
what does the II fibers detect
static stretch only bcs connected lang sha c nuclear chain
what is the significance of nuclear bag and chain
NB - for dynamic response
NC - static response
what is the structure of the polar ends
may gamma motor efferent fibers
in what fiber is dynamic stretch present
Ia only bcs NB
in what fiber is static stretch present
Ia and II bcs NC
compare intra and extra fusal m fibers in terms of nuerons present
intra - gamma
extra - alpha
examples of dynamic stretch
DTR and sudden stretch
stretching used if there are contractures
positional stretching
examples of static stretch
usual na stretching; slow
explain the process of stretch reflex
lengthened muscle = excites NB and NC - type Ia and II to signal SC
signal goes to SC and synapse c DRG = coactivation of gamma and alpha motor neuron
gamma - gives efferent signal to polar end if IMF
alpha - stimulate EMF
= muscle contracts
explain the process of inverse stretch reflex
when muscle contracts = tension = GTO stretch on both sides = Ib fibers stimulated
Ib fibers synapse c DRG = alpha motor neuron will be inhibited = no signal to extrafusal
= muscle does not contract = relax
explain autogenic inhibition
GTO - relax of agonist; contraction of antagonist
explain reciprocal inhibition
muscle spindle - contraction of agonist; relax antagonist
what is monoreflex and give an example
one pathway lng daan gang spinal cord lang - knee jerk
what is polyreflex and give an example
aakyat pa reflex sa brain ma pprocess gannun may multiple pathways - withdrawal reflex
what is arreflexia
pure absence of DTR - cut both efferent and afferent pathways
what is hyporeflexia
diminished reflex - may blockage lng sa conduction
what is hyperreflexia
very brisk or conus reflex - UMN lesion maaffect corticospinal tract so ma sstop conductio of renshaw cells that will inhibit or control the reflex
explain conus reflex
rhythmic involuntary contraction - spasticity usually seen in stroke patients
significance of jendrassik maneuver
will elicit true reflex kase mappunta renshaw sa upper half ng body
what are primitive reflexes
survival reflex and can be seen sa bata or sa stroke pt
what are physiological reflex
survival reflex of adults
what is palmomental reflex
primitive reflex - twitch yung chin when stroked thenar eminence of palm
