ANS

Question 1

1. There is a hierarchical level of organization of how different groups of neurons (nuclei) control motor movement
   a) Simple reflexes: **. This is the ** form of motor control
   b) Central Pattern Generators (CPGs): **
   c) Complex/Volitional Movement: **

Answer 1

1. There is a hierarchical level of organization of how different groups of neurons (nuclei) control motor movement
   a) Simple reflexes: Sensory neurons make synapses with spinal cord motoneurons to
   mediate simple reflexes. This is the simplest form of motor control
   b) Central Pattern Generators (CPGs): Networks of interneurons in the spinal cord and brainstem coordinate the interaction of many different motor groups (locomotion,
   respiration)
   c) Complex/Volitional Movement: Motor output that is planned and refined by the motor cortex, basal ganglia and cerebellum

Question 2

1. Reflexes
   a) **
   b) ‘** of a sensory stimulus within the CNS to **
   c) Perform a specific task; often a f** regulating **, **, etc.
2. Reflect Loop
   a) Monosymnaptic reflex **
   b) Polysynaptic refleces have **

Answer 2

1. Reflexes
   a) Basic element of motor control
   b) ‘Bending back’ of a sensory stimulus within the CNS to produce a motor response
   c) Perform a specific task; often a feedback loop regulating force, position, etc.
2. Reflect Loop
   a) Monosymnaptic reflex has a single synpase between the afferent and efferent neurons
   b) Polysynaptic refleces have two or more synpases. this somatic motor reflex has both synpases in the CNS

Question 3

1. Stretch Reflex
   a) You , it will **”
   b) Operates at ** level
   c) Stimulus: **
   d) Response:**; e.g. patellar tendon reflex
   e) Very sensitive and fast due to ** **, and **
   connection to **
2. steps
   a) **
   b) **
   c) **
3. Stretch Reflex Properties
   a) Essential for **
   b) Reflex strongest in **
   c) Latencies of about ** ms for forearm muscles, ** ms for ankle extensors
   d) ** paths through spinal cord (branches up to **as well)
   e) Stretch reflex and all other reflexes are designed for a ** (e.g.
   **)
   f) During movement, ** suppressed

Answer 3

1. Stretch Reflex
   a) You stretch it, it will contract”
   b) Operates at subconscious level
   c) Stimulus: passive stretch of a muscle by applied load or contraction of antagonist muscle
   d) Response: active contraction of muscle; e.g. patellar tendon reflex
   e) Very sensitive and fast due to muscle spindle afferents, and monosynaptic
   connection to motoneurons
2. steps
   a) Place a load on the hand
   b) Load > will activate muscle spindle
   (direct connection with the motoneuron)
   c) Activate the motoneuron > contraction of the same muscle that was stretched
3. Stretch Reflex Properties
   a) Essential for stabilizing posture
   b) Reflex strongest in postural muscles
   c) Latencies of about 25 ms for forearm muscles, 37 ms for ankle extensors
   d) Parallel multisynaptic paths through spinal cord (branches up to somatosensory
   cortex as well)
   e) Stretch reflex and all other reflexes are designed for a specific function (e.g.
   stabilizing a joint)
   f) During movement, reflex suppressed

Question 4

1. Golgi Tendon Reflex
   a) “You contract it, it will relax”: Muscle contraction ** Goldi tendon organ, if excessive load is placed on muscle, Goldi tendon reflex causes **thus **
   b) ** synapse on ** in i** of **
   c) Interneurons inhibit ** of ** muscle
   d) Stimulus: **
   e) Response: **
   *Regulate the ** –Complementary to **
   * Over exertion of the muscle > activates ** > activate **
   * Interneurons > inhibit ** (reduce **) – To regulate the **
   * Excessive load > muscle **
   * Load is ** but muscle is **
   Step 1. **
   Step 2. **
   Step 3. **
   Step 4. **
2. Golgi Tendon Reflex Properties
   * Prevents **
   * Acts in concert with ** to **
   * Suppressed when **

Answer 4

1. Golgi Tendon Reflex
   a) “You contract it, it will relax”: Muscle contraction stretches Goldi tendon organ, if excessive load is placed on muscle, Goldi tendon reflex causes relaxtion thus protecting muscle
   b) GTO afferents synapse on interneurons in intermediate zone of spinal cord
   c) Interneurons inhibit motoneurons of same muscle
   d) Stimulus: active tension in muscle
   e) Response: relaxation or reduction of tension
   *Regulate the level of activity –Complementary to stretch reflex
   * Over exertion of the muscle > activates GTO > activate interneurons
   * Interneurons > inhibit motoneuron (reduce contraction) – To regulate the amount of force
   * Excessive load > muscle relaxes
   * Load is dropped but muscle is saved
   Step 1. Neuron from Goldi tendon organ fires
   Step 2. Motor neuron is inhibited
   Step 3. Muscle releases
   Step 4. Load is dropped
2. Golgi Tendon Reflex Properties
   * Prevents movement
   * Acts in concert with stretch reflex to stabilize posture
   * Suppressed when net motion is desired

Question 5

1. Stretch & Golgi Tendon Reflexes
   * Over activation of biceps > ** >
   reduce activity in biceps
   * Over activation of biceps > **) >
   ** > **

Answer 5

1. Stretch & Golgi Tendon Reflexes
   * Over activation of biceps > GTR >
   reduce activity in biceps
   * Over activation of biceps > stretch of
   the triceps (antagonistic muscle) >
   stretch reflex > contraction of triceps

Question 6

1. Flexion Withdrawal Reflex
   * “You touch hot stove, ”
   * Stimulus: **
   * Response: ** (extension distal to stimulus)
   * ** synapse on ** in sn – Slowly conduction afferents
   * Multi-synaptic path to **
   * Activate ** in ** >
   flexion of the ** & extension of the **

Answer 6

1. Flexion Withdrawal Reflex\
   * “You touch hot stove, flex your arm”
   * Stimulus: noxious injury of limb
   * Response: flexion of joints proximal to stimulus (extension distal to stimulus)
   * Nociceptor afferents synapse on interneurons in superficial dorsal horn – Slowly conduction afferents
   * Multi-synaptic path to motoneurons
   * Activate pain receptors in forearm >
   flexion of the proximal join & extension of the distal joint

Question 7

1. Reciprocal Inhibition
   * Activation of ** is coupled to **
   * e.g. activation of flexor motoneurons
   elicits **
   * When co-contraction of antagonists
   desired (for joint stiffness) this **

Answer 7

1. Reciprocal Inhibition
   * Activation of one motor nucleus is coupled to inhibition of antagonistic motor nucleus
   * e.g. activation of flexor motoneurons
   elicits inhibition of antagonist extensors
   * When co-contraction of antagonists
   desired (for joint stiffness) this circuit
   is suppressed

Question 8

1. Patellar Tendon Reflex
   * “You bang your knee, you kick”
   * Tap on patellar tendon > stretch
   quads > contraction of quads
   * Simultaneously inhibit hamstrings
   contraction
2. Cross Extension Reflex
   * “You step on something sharp, flex your leg where there is pain & extend the other leg”
   * Full expression of the flexion withdrawal reflex involves contralateral extension for increased postural support > mainly seen in
   legs
   * Commissural interneurons carry signal to contralateral spinal cord
3. Extensor Thrust Reflex
   Stimulus: pressure on sole of foot (innocuous)
   * Response: activation of leg extensors
   * Mechanoreceptors project to intermediate zone interneurons > extensor motoneurons
   * Reflex operates only during stance

Answer 8

1. Patellar Tendon Reflex
   * “You bang your knee, you kick”
   * Tap on patellar tendon > stretch
   quads > contraction of quads
   * Simultaneously inhibit hamstrings
   contraction
2. Cross Extension Reflex
   * “You step on something sharp, flex your leg where there is pain & extend the other leg”
   * Full expression of the flexion withdrawal reflex involves contralateral extension for increased postural support > mainly seen in
   legs
   * Commissural interneurons carry signal to contralateral spinal cord
3. Extensor Thrust Reflex
   Stimulus: pressure on sole of foot (innocuous)
   * Response: activation of leg extensors
   * Mechanoreceptors project to intermediate zone interneurons > extensor motoneurons
   * Reflex operates only during stance

Question 9

1. Babinski Sign
   * Extensor thrust reflex is influenced
   by **
   * Can be elicited at ** (in the **) by
   **
   * If ** tract is damaged
   (stroke, spinal injury), the reflex pattern is **

Answer 9

1. Babinski Sign
   * Extensor thrust reflex is influenced
   by corticospinal tract
   * Can be elicited at rest (in the toes) by
   vigorous stroking of sole of foot
   * If corticospinal tract is damaged
   (stroke, spinal injury), the reflex pattern is switched to flexion withdrawal

Question 10

Vestibulo-Spinal Reflex
* Stimulus: **  activates **
* Response: **
* Otolith afferents activate **: **
projection to **
* Postural reflex - **

Answer 10

Vestibulo-Spinal Reflex
* Stimulus: downward deviation of
head on one side  activates otolith
afferents
* Response: ‘downhill’ limbs extend
* Otolith afferents activate lateral
vestibulo-spinal tract: ipsilateral
projection to extensor (antigravity)
motor nuclei
* Postural reflex - Reflex latency in legs
about 80 ms