Flashcards in Spinal Level Reflexes Deck (16)
Characteristics of Spinal level reflexes?
1. Involuntary responses to stimuli
2. Monosynaptic or polysynaptic (involve interneurons)
3. Basis for unconscious motor function and basic defense mechanisms
What is the stimulus for Stretch (myotactic) Reflexes?
What is the function of Myotatic Reflexes?
Functions for Maintenance of (1) muscle tone (2) support agonist muscle contraction and (3) provide feedback about muscle length
Describe the reflex arc for myotatic reflexes.
Afferent (away from brain) Ia fiber from muscle spindle to alpha motor neurons projecting back to muscles of origin (monosynaptic)
Who is the stretch reflex clinically tested?
Apply stretch to deep tendons
Describe Reciprocal inhibition
Via an inhibitory interneuron. The same stretch stimulus inhibits the ANTAGONIST muscle
Reciprocal innervation describes what?
Describes the effect of a stretch stimulus on agonist (autogenic facilitation), antagonist (reciprocal inhibition), and synergistic muscles (facilitation)
What is the stimulus for Inverse Stretch (Myotatic) Reflex?
What is the Reflex arc for inverse stretch reflex?
Multiple sensory receptors and corresponding fiber types activate inhibitory interneuron to muscle of origin (polysynaptic)
What is the function of the inverse stretch reflex?
Provide agonist inhibition, diminution of force of agonist contraction, stretch-protection reflex
True or false: the stretch reflex forms part of the gamma reflex loop
What does the gamma reflex loop allow?
Allows muscle tension to come under control of descending pathways (reticulospinal, vestibulospinal, and others)
True or false: descending pathways excite gamma motor neurons, causing contraction of muscle spindle, and in turn increased stretch sensitivity and increased rate of firing form spindle afferents; impulse are then conveyed to alpha motor neurons
What is the stimulus for the Flexor (withdrawal) reflex?
Cutaneous sensory stimuli
What is the function of the flexor (withdrawal reflex)?
Functions as protective withdrawal mechanism to remove body part from harmful stimuli