13 Motor System

Question 1

-system that directs the voluntary control of muscles, from the simplest movements to the most complex.

-the simplest movement is highly integrated here and requires inputs from different areas of the central and peripheral nervous systems.

-It is the system behind the initiation and regulation of locomotion.

Answer 1

motor system

Question 2

The motor system includes?

Answer 2

cerebral motor cortex

basal nuclei

cerebellum

brainstem

spinal cord

peripheral nerves

Question 3

Locomotion relies on three key components of body movements:

Answer 3

voluntary

reflex

rhythmic

Question 4

-is directed by the primary motor cortex

-Its task is to synthesize numerous signals into patterns of action in coordination with the cerebral cortex, basal nuclei, and cerebellum.

Answer 4

Voluntary movement

Question 5

-The motor cortex and brainstem motor centers give rise to the ____ that control motor neurons innervating skeletal muscles.

-also act on the local reflex circuitries to maintain posture and muscle tone, and on the central pattern generator in the spinal cord to initiate, modify, or terminate the locomotor activity.

Answer 5

descending motor tracts

Question 6

what initiates voluntary movements

Answer 6

Cerebral cortex

Question 7

three descending motor tracts of the cerebral motor cortex:

Answer 7

corticonuclear

corticopontine

corticospinal

Question 8

What tract descends to reach its target nuclei in the brainstem. This tract mediates such voluntary actions as eye movements, mastication, facial expression, swallowing, neck movement, and tongue movement.

Answer 8

Corticonuclear tract

Question 9

What tract terminates in the pons and synapses with neurons that send their axons, as the pontocerebellar fibers, to the contralateral cerebellum. This is one of several ways the cerebellum monitors cerebral motor activities.

Answer 9

Corticopontine tract

Question 10

What tract is a crossed pathway, as most of its fibers cross (75% or so in dogs) at the pyramidal decussation and descend as the lateral corticospinal tract in the contralateral side of the spinal cord. The remaining fibers stay in the ipsilateral side of the spinal cord and descend as the ventral corticospinal tract.

Answer 10

Corticospinal tract

Question 11

Three key motor nuclei in the brainstem?

Answer 11

red nucleus of the midbrain

pontine and medullary reticular formation

vestibular nuclei in the medulla oblongata

Question 12

gives rise to the rubrospinal tract, which is functionally similar to the lateral corticospinal tract. In animals, the rubrospinal tract is a key motor tract for voluntary movement. The primary role of this tract is to control the flexor motor system and fine movements of the extremities.

Answer 12

red nucleus of the midbrain

Question 13

gives rise to the pontine and medullary reticulospinal tracts. These descending motor tracts maintain the muscle tone necessary for supporting the body against gravity, as well as postural adjustment and synergic movements of the body.

Answer 13

reticular formation

Question 14

facilitates spinal motor neurons (alpha, gamma) that supply the extensor muscles, but it simultaneously inhibits motor neurons to the flexor muscles.

Answer 14

pontine reticulospinal tract

Question 15

opposes the pontine reticulospinal tract by inhibiting spinal motor neurons (alpha, gamma) that supply the extensor muscles and simultaneously facilitate motor neurons for flexor muscles.

Answer 15

medullary reticulospinal tract

Question 16

give rise to two descending tracts, the medial and lateral vestibulospinal tracts. They descend in the ventral funiculus of the spinal cord. They maintain the balance of the body by facilitating lower motor neurons for extensor muscles and inhibiting lower motor neurons for flexor muscles.

Answer 16

vestibular nuclei in the medulla oblongata

Question 17

Motor neurons are classified as

Answer 17

Upper motor neurons

Lower motor neurons

Question 18

What motor neurons are responsible for voluntary muscle control, regulation of muscle tone, and maintenance of posture against gravity. They do not innervate the skeletal muscle directly but influence the lower motor neurons.

Answer 18

Upper motor neurons

Question 19

What motor neurons leave the central nervous system (CNS) and innervate skeletal muscles

Answer 19

Lower motor neurons

Question 20

The basal nuclei consist of

Answer 20

caudate nucleus

putamen

globus pallidus

Question 21

-coordinates complex movements of the body by influencing the cerebral motor cortex and other major motor centers (e.g., red nucleus, reticular formation) in the brainstem.

-modulate cerebral motor outputs by acting on the primary motor cortex via the thalamus.

-regulates the learning of motor skills

Answer 21

Basal nuclei

Question 22

-a relatively simple involuntary response to a specific sensory stimulus.

-an integral part of maintaining muscle tone and posture.

-is either monosynaptic or polysynaptic in type

Answer 22

Reflex

Question 23

It is the simplest type reflex. It requires peripheral sensory neurons that bring sensory signals
from sensory receptors to the spinal cord and central motor neurons that respond to sensory signals by triggering the contraction of skeletal muscles.

Answer 23

monosynaptic reflex

Question 24

type of reflex that involves one or more interneurons connecting afferent (sensory) and efferent (motor) signals.

Answer 24

polysynaptic reflex

Question 25

The voluntary and reflex motor control produce coordinated patterns of?

Answer 25

rhythmic activity

Question 26

cycle that is used to describe the complex activity of locomotion, from the initial placement of the supporting heel on the ground to when the same heel contacts the ground for a second time.

Answer 26

Gait cycle

Question 27

step cycle of locomotion consists of

Answer 27

the swing phase

the stance phase

Question 28

Rhythmic pattern of walking relies on the central pattern generator in the:

Answer 28

Thoracolumbar spinal cord