Motor Function Of Spinal Cord Physiology

Question 1

building blocks for the movements

Answer 1

motor units.

Question 2

final common pathway out of the CNS

Answer 2

motor neurons

Question 3

Why are motor neurons the final common pathway of CNS

Answer 3

because all neural influences on skeletal muscle meet on the motor neurons and can only affect skeletal muscle through them.

Question 4

The cell bodies of the motor neuron pool for a given muscle are close to each other either in

Answer 4

ventral horn of the spinal cord or in the brainstem.

Question 5

Within the brainstem or spinal cord, the axons of many neurons synapse on a motor neuron, why

Answer 5

to control its activity.

Question 6

Although no single input to a motor neuron is essential for contraction of the muscle fibers it innervates, a balanced input from all sources is necessary to

Answer 6

provide the precision and speed of normally coordinated actions

Question 7

All body movements are achieved by

Answer 7

activation, in a precise sequence, of many motor units in various muscles.

Question 8

To begin a movement, a general intention is generated attention

Answer 8

the highest level of the motor

control hierarchy.

Question 9

Motor control of the skeletal system is orgainzed like ….. and the levels are

Answer 9

Pyramid
Highest level
Middle level
Local level

Question 10

Highest levels

Answer 10

Higher centers (regions of the brain, including those involved in memory, emotions, and motivation)

Question 11

Middle levels

Answer 11

Sensorimotor cortex
Basal nuclei
Thalamus
Cerebellum
Brainstem

Question 12

Local levels

Answer 12

Brainstem and spinal cord

Receptors

Question 13

Information is relayed from these higher-center “command” neurons to

Answer 13

parts of the brain that

make up the middle level of the motor control hierarchy.

Question 14

The middle-level hierarchical structures are located in

Answer 14

parts of the cerebral cortex as well as in the cerebellum, subcortical nuclei, and brainstem and thalamus

Question 15

The basal ganglia are

Answer 15

Cluster of sub cortical ganglia

Question 16

The structures of the middle level have

Answer 16

extensive interconnections

Question 17

The middle-level structures function

Answer 17

specify the individual postures and movements needed to carry out the intended action.

Question 18

The neurons in the middle level of the hierarchy receive ……
from receptors in …….

Answer 18

afferent information

the muscles, tendons, joints, and skin, as well as from the vestibular apparatus and eyes.

Question 19

middle level of the hierarchy relay information about

Answer 19

the nature of the space just outside the body in which a movement will take place.

Question 20

The information determined by the motor program is transmitted via …… pathways to the………

Answer 20

descending

local level of the motor control hierarchy

Question 21

In the local level of the motor control hierarchy the motor neurons to the muscles

Answer 21

exit the brainstem or spinal cord

Question 22

The local level of the hierarchy includes what neurons

Answer 22

afferent neurons, motor neurons, and the interneurons whose function is related to them.

Question 23

Local level neurons determine

Answer 23

exactly which motor neurons will be activated to achieve the desired action and when this will happen

Question 24

The descending pathways to the local level arise only in

Answer 24

sensorimotor cortex and brainstem

Question 25

Other brain areas exert their effects on the local level only indirectly, via the descending pathways from the cerebral cortex and brainstem. What are those brain areas

Answer 25

the basal nuclei (also referred to as the basal ganglia), thalamus, and cerebellum

Question 26

The motor programs are continuously adjusted during

Answer 26

the course of most movements.

Question 27

As the initial motor program begins and the action gets underway, brain regions at the middle level of the hierarchy continue to receive

Answer 27

a constant stream of updated afferent information about the movements taking place.

Question 28

proprioception

Answer 28

Afferent information about the position of the body and its parts in space is called