Control of Body Movement
3. Picking up a book, for example, has both voluntary and
involuntary components. List the components of this action
and indicate whether each is voluntary or involuntary.
4. List the inputs that can converge on the interneurons active in
local motor control.
5. Draw a muscle spindle within a muscle, labeling the spindle,
intrafusal and extrafusal muscle ﬁ bers, stretch receptors,
afferent ﬁ bers, and alpha and gamma efferent ﬁ bers.
6. Describe the components of the knee jerk reﬂ ex (stimulus,
receptor, afferent pathway, integrating center, efferent pathway,
effector, and response).
7. Describe the major function of alpha-gamma coactivation.
8. Distinguish among the following areas of the cerebral cortex:
sensorimotor, primary motor, premotor, and supplementary
9. Contrast the two major types of descending motor pathways in
terms of structure and function.
10. Describe the roles that the basal nuclei and cerebellum play in
11. Explain how hypertonia might result from disease of the
12. Explain how hypotonia might result from lower motor neuron
13. Explain the role the crossed-extensor reﬂ ex plays in postural
14. Explain the role of the interneuronal networks in walking,
incorporating in your discussion the following terms:
interneuron, reciprocal innervation, synergist, antagonist, and
e. Afferent neurons to the sensorimotor cortex stimulate
the agonist muscle to contract and the antagonist
muscle to be inhibited.
3. Which would result in reﬂ ex contraction of the extensor
muscles of the right leg?
a. stepping on a tack with the left foot
b. stretching the ﬂ exor muscles in the right leg
c. dropping a hammer on the right big toe
d. action potentials from Golgi tendon organs in extensors of
the right leg
e. action potentials from muscle-spindle receptors in ﬂ exors of
the right leg
4. If implanted electrodes were used to stimulate action
potentials in gamma motor neurons to ﬂ exors of the left arm,
which would be the most likely result?
a. inhibition of the ﬂ exors of the left arm
b. a decrease in action potentials from muscle-spindle
receptors in the left arm
c. a decrease in action potentials from Golgi tendon organs in
the left arm
d. an increase in action potentials along alpha motor neurons
to ﬂ exors in the left arm
e. contraction of ﬂ exor muscles in the right arm
upper motor neuron
Chapter 10 Test Questions
(Answers appear in Appendix A.)
1. Which is a correct statement regarding the hierarchical
organization of motor control?
a. Skeletal muscle contraction can only be initiated by neurons
in the cerebral cortex.
b. The basal nuclei participate in the creation of a motor
program that speciﬁ es the pattern of neural activity required
for a voluntary movement.
c. Neurons in the cerebellum have long axons that synapse
directly on alpha motor neurons in the ventral horn of the
d. The cell bodies of alpha motor neurons are found in the
primary motor region of the cerebral cortex.
e. Neurons with cell bodies in the basal nuclei can either form
excitatory or inhibitory synapses onto skeletal muscle cells.
2. In the stretch reﬂ ex:
a. Golgi tendon organs activate contraction in extrafusal
muscle ﬁ bers connected to that tendon.
b. Lengthening of muscle-spindle receptors in a muscle leads
to contraction in an antagonist muscle.
c. Action potentials from muscle-spindle receptors in a muscle
form monosynaptic excitatory synapses on motor neurons to
extrafusal ﬁ bers within the same muscles.
d. Slackening of intrafusal ﬁ bers within a muscle activates
gamma motor neurons that form excitatory synapses with
bers within that same muscle.
stretch reﬂ ex
supplementary motor cortex
upper motor neurons
withdrawal reﬂ ex
1. Describe motor control in terms of the conceptual motor
control hierarchy. Use the following terms: highest, middle,
and local levels; motor program; descending pathways; motor
2. List the characteristics of voluntary actions.