Spinal Reflexes

Question 1

What do reflexes provide information about?

Answer 1

Peripheral and spinal circuits

Question 2

What role does the brain play in reflexes?

Answer 2

Does not require the brain (it may have some influence over background level activity of spinal cord)

Question 3

What are the Phasic stretch reflexes?

Answer 3

Muscle stretch or DTR (patellar reflex)

Monosynaptic reflex

Abnormal myotatic reflex

Question 4

What is the pathway of a DTR? (Brief response)

Answer 4

Ia afferents

Spinal cord

Synapse

Alpha motor neuron(which then depolarizes and stimulates muscle fibers to contract)

Question 5

Where are tonic stretch reflexes present?

Answer 5

UMN

Question 6

What is a sustained stretch?

Answer 6

Ia and II afferent neurons

Spinal cord

Multiple interneurons

LMN

Question 7

How does a sustained stretch work in an undamaged nervous system?

Answer 7

Does not elicit reflexive contraction due to Presynaptic inhibition

Question 8

How does a sustained stretch work in a damaged nervous system?

Answer 8

Sustained firing of spindle due to loss of Presynaptic inhibition

Question 9

What can affect reflexive response?

Answer 9

Arousal levels

Relaxed- diminished

Anxious- exaggerated

Question 10

What is reciprocal inhibition?

Answer 10

Inhibit antagonist muscle during agonist contraction (done by inhibitory neuron)

Question 11

What are muscle synergies?

Answer 11

Coordinated muscular action (help eachother)