PSL300 - Motor, ANS & Muscle Exam
Questions and Answers Graded A+
Simple reflexes - Correct answer-Sensory neurons make synapses with spinal cord
motoneurons to mediate simple reflexes. This is the simplest form of motor control
Central Pattern Generators (CPGs) - Correct answer-Networks of interneurons in
the spinal cord and brainstem coordinate the interaction of many different motor
groups (locomotion, respiration)
Complex/Volitional Movement - Correct answer-Motor output that is planned and
refined by the motor cortex, basal ganglia and cerebellum
Monosynaptic reflex - Correct answer-- Has a single synapse between the afferent
and efferent neurons
- Stimulus to receptor to sensory neuron to CNS to efferent neuron to target cell to
response
Polysynaptic reflexes - Correct answer-- Have two or more synapses. This somatic
motor reflex has both synapses in the CNS.
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
,- Stimulus to receptor to sensory neuron to interneuron in CNS to efferent neuron
to target cell to response
Stretch Reflex - Correct answer-- You stretch it, it will contract"
- operates at subconscious level
- stimulus: passive stretch of a muscle by applied load or contraction of antagonist
muscle
- response: active contraction of muscle; e.g. patellar tendon reflex
- very sensitive and fast due to muscle spindle afferents, and monosynaptic
connection to motoneurons
Stretch Reflex Properties - Correct answer-- essential for stabilizing posture
- reflex strongest in postural muscles
- latencies of about 25ms for forearm muscles, 37ms for ankle extensors
- parallel multisynaptic paths through spinal cord (branches up to somatosensory
cortex as well)
- stretch reflex and all other reflexes are designed for a specific function (e.g.
stabilizing a joint)
- during movement, reflex suppressed
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
,Golgi Tendon Reflex - Correct answer-- "You contract it, it will relax"
- GTO (Golgi tendon organ) afferents synapse on interneurons in intermediate zone
of spinal cord
- interneurons inhibit motoneurons of same muscle
- stimulus: active tension in muscle
- response: relaxation or reduction of tension
- it regulates the level of activity by inhibition - complementary to stretch reflex
- over exertion of the muscle => activates GTO => activates interneurons
- interneurons => inhibit motoneurons (reduce contraction): to regulate the amount
of force
- excessive load => muscle relaxes => load is dropped but muscle is saved
Golgi Tendon Reflex Properties - Correct answer-- Prevents movement
- Acts in concert with stretch reflex to stabilize posture
- Suppressed when net motion is desired
Stretch and Golgi Tendon Reflexes - Correct answer-- if there is overactivation of
biceps
- GTR will reduce activity in biceps
©COPYRIGHT 2025, ALL RIGHTS RESERVED 3
, - if there is overactivation of biceps
- triceps (antagonistic muscle) stretches
- stretch reflex
- contraction of triceps
Flexion Withdrawal Reflex - Correct answer-- "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 joint and extension
of the distal joint
Reciprocal inhibition - Correct answer-- activation of one motor nucleus is coupled
to inhibitoin of antagonistic motor nucleus
- e.g. activation of flexor motoneurons elicits inhibition of antagonist extensors
©COPYRIGHT 2025, ALL RIGHTS RESERVED 4
Questions and Answers Graded A+
Simple reflexes - Correct answer-Sensory neurons make synapses with spinal cord
motoneurons to mediate simple reflexes. This is the simplest form of motor control
Central Pattern Generators (CPGs) - Correct answer-Networks of interneurons in
the spinal cord and brainstem coordinate the interaction of many different motor
groups (locomotion, respiration)
Complex/Volitional Movement - Correct answer-Motor output that is planned and
refined by the motor cortex, basal ganglia and cerebellum
Monosynaptic reflex - Correct answer-- Has a single synapse between the afferent
and efferent neurons
- Stimulus to receptor to sensory neuron to CNS to efferent neuron to target cell to
response
Polysynaptic reflexes - Correct answer-- Have two or more synapses. This somatic
motor reflex has both synapses in the CNS.
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
,- Stimulus to receptor to sensory neuron to interneuron in CNS to efferent neuron
to target cell to response
Stretch Reflex - Correct answer-- You stretch it, it will contract"
- operates at subconscious level
- stimulus: passive stretch of a muscle by applied load or contraction of antagonist
muscle
- response: active contraction of muscle; e.g. patellar tendon reflex
- very sensitive and fast due to muscle spindle afferents, and monosynaptic
connection to motoneurons
Stretch Reflex Properties - Correct answer-- essential for stabilizing posture
- reflex strongest in postural muscles
- latencies of about 25ms for forearm muscles, 37ms for ankle extensors
- parallel multisynaptic paths through spinal cord (branches up to somatosensory
cortex as well)
- stretch reflex and all other reflexes are designed for a specific function (e.g.
stabilizing a joint)
- during movement, reflex suppressed
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
,Golgi Tendon Reflex - Correct answer-- "You contract it, it will relax"
- GTO (Golgi tendon organ) afferents synapse on interneurons in intermediate zone
of spinal cord
- interneurons inhibit motoneurons of same muscle
- stimulus: active tension in muscle
- response: relaxation or reduction of tension
- it regulates the level of activity by inhibition - complementary to stretch reflex
- over exertion of the muscle => activates GTO => activates interneurons
- interneurons => inhibit motoneurons (reduce contraction): to regulate the amount
of force
- excessive load => muscle relaxes => load is dropped but muscle is saved
Golgi Tendon Reflex Properties - Correct answer-- Prevents movement
- Acts in concert with stretch reflex to stabilize posture
- Suppressed when net motion is desired
Stretch and Golgi Tendon Reflexes - Correct answer-- if there is overactivation of
biceps
- GTR will reduce activity in biceps
©COPYRIGHT 2025, ALL RIGHTS RESERVED 3
, - if there is overactivation of biceps
- triceps (antagonistic muscle) stretches
- stretch reflex
- contraction of triceps
Flexion Withdrawal Reflex - Correct answer-- "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 joint and extension
of the distal joint
Reciprocal inhibition - Correct answer-- activation of one motor nucleus is coupled
to inhibitoin of antagonistic motor nucleus
- e.g. activation of flexor motoneurons elicits inhibition of antagonist extensors
©COPYRIGHT 2025, ALL RIGHTS RESERVED 4
