NEUR 2026 Exam 2 Material Questions
and Graded Answers.
Where do upper motor neurons reside? - Neurons that reside in higher motor centers
(cortex)
What is the function of the upper motor neurons? - they regulate movement by
influencing lower motor neuron circuits in the brain stem and spinal cord
Where do lower motor neurons reside? - somas are in the spinal cord and brainstem
What is the function of the lower motor neurons? - reside in ventral horn of spinal cord
and send efferent fibers out to musculature and viscera; directly innervate skeletal muscles
Where are motor neurons that control proximal muscles found in the spinal cord and what do
they control? - They are located medially in the spinal cord and they control the neck
shoulders, back, etc.
Where are motor neurons that control distal muscles found in the spinal cord and what do they
control? - They are located laterally in the ventral horn of the spinal cord and are
responsible for controlling arms, hands, legs, etc.
Motor unit - a particular a-motor neuron and all the muscle fibers it innervates (motor
neurons branch their fibers and synapse onto several muscle fibers)
Motor neuron pool - all the a-motor neurons that innervate a single muscle.
Motor endplate - region of the muscle fiber where the motor neuron axon terminates.
, NMJ - synapse at the motor endplate
Describe the function and properties of fast fatigable motor units. - They are used for
strenuous activities like jumping
-show a very fast, strong increase in force
-response quickly dwindles due to fatigue (~1 minute)
Describe the function and properties of fast fatigue-resistant motor units. - intermediate
force required for walking or running
-slower and have intermediate force
-intermediate force response that maintains over time (6 min)
Describe the function and properties of slow motor units. - provide low level force, but
sufficient for prolonged standing
-slow and minimally forceful
-maintain for 60+ minutes
reflexes - rapid, stereotyped, involuntary movements; an automatic response, always the
same, over and over again.
What are examples of relfexes? - knee-jerk reflex
- tapping the patellar tendon stretches the quadriceps extensor muscle --> triggers activation of a-
motor neuron to contract the same neuron
flexion withdraw reflex
-nociceptive stimulus leads to flexion/withdrawal of the affected limb and extension of the
opposite limb.
rhythmic motor patterns - voluntarily initiated and terminated, maintained through reflex
and Graded Answers.
Where do upper motor neurons reside? - Neurons that reside in higher motor centers
(cortex)
What is the function of the upper motor neurons? - they regulate movement by
influencing lower motor neuron circuits in the brain stem and spinal cord
Where do lower motor neurons reside? - somas are in the spinal cord and brainstem
What is the function of the lower motor neurons? - reside in ventral horn of spinal cord
and send efferent fibers out to musculature and viscera; directly innervate skeletal muscles
Where are motor neurons that control proximal muscles found in the spinal cord and what do
they control? - They are located medially in the spinal cord and they control the neck
shoulders, back, etc.
Where are motor neurons that control distal muscles found in the spinal cord and what do they
control? - They are located laterally in the ventral horn of the spinal cord and are
responsible for controlling arms, hands, legs, etc.
Motor unit - a particular a-motor neuron and all the muscle fibers it innervates (motor
neurons branch their fibers and synapse onto several muscle fibers)
Motor neuron pool - all the a-motor neurons that innervate a single muscle.
Motor endplate - region of the muscle fiber where the motor neuron axon terminates.
, NMJ - synapse at the motor endplate
Describe the function and properties of fast fatigable motor units. - They are used for
strenuous activities like jumping
-show a very fast, strong increase in force
-response quickly dwindles due to fatigue (~1 minute)
Describe the function and properties of fast fatigue-resistant motor units. - intermediate
force required for walking or running
-slower and have intermediate force
-intermediate force response that maintains over time (6 min)
Describe the function and properties of slow motor units. - provide low level force, but
sufficient for prolonged standing
-slow and minimally forceful
-maintain for 60+ minutes
reflexes - rapid, stereotyped, involuntary movements; an automatic response, always the
same, over and over again.
What are examples of relfexes? - knee-jerk reflex
- tapping the patellar tendon stretches the quadriceps extensor muscle --> triggers activation of a-
motor neuron to contract the same neuron
flexion withdraw reflex
-nociceptive stimulus leads to flexion/withdrawal of the affected limb and extension of the
opposite limb.
rhythmic motor patterns - voluntarily initiated and terminated, maintained through reflex
