7-2

Question 1

Primary motor cortex:

Answer 1

stimulation of this area elicits movements, although it is not directly connected to the muscles.
Axons from the primary motor cortex go to the brainstem and spinal cord
particularly important for complex actions such as writing, and less important for coughing, sneezing
Stimulation of the motor cortex can elicit complex movement patterns.
Imagining a movement can also activate it.

Question 2

Two Dorsolateral

Answer 2

Corticospinal

Corticorubrospinal

Question 3

Two Ventromedial

Answer 3

Corticospinal

Cortico-brainstem-spinal tract

Question 4

Corticospinal - DT

Answer 4

descend through the medullary pyramids, then decussate

• Betz cells
• Control of wrist, hands, fingers, toes

Question 5

bets cells

Answer 5

synapse on motor neurons projecting to muscles

Question 6

Corticorubrospinal

Answer 6

synapse at red nucleus and cross before the medulla

• Some control muscles of the face
• Distal muscles of arms and legs

Question 7

Corticospinal - VT

Answer 7

Descends ipsilaterally

Axons branch and innervate interneuron circuits bilaterally in multiple spinal segments.

Question 8

Cortico-Brainstem-Spinal

Answer 8

Interacts with various brainstem structures and descends bilaterally, carrying information from both hemispheres
Synapses on interneurons of multiple spinal segments controlling proximal trunk and limb muscles

Question 9

Dorsolateral

Answer 9

• One direct tract, one that synapses in the brain stem
• Terminate in one contralateral spinal segment
• Distal muscles
• Limb movements

Question 10

Ventromedial

Answer 10

• One direct tract, one that synapses in the brain stem
• More diffuse
• Bilateral innervation
• Proximal muscles
• Posture and whole body movement

Question 11

All animal movement depends on

Answer 11

muscle contractions

Question 12

Muscle

Answer 12

muscle fibers bound together by a tendon

Question 13

Smooth Muscle

Answer 13

control the digestive system and other organs

Question 14

Skeletal muscles/striated muscles

Answer 14

control movement of the body in relation to the environment

Question 15

Cardiac muscles

Answer 15

heart muscles that have properties of skeletal and smooth muscles

Question 16

Motor units

Answer 16

a motor neuron plus muscle fibers; all fibers contract when the motor neurone fires
- Number of fibers per unit varies

Question 17

fine control

Answer 17

= fewer fibers/neuron

Question 18

Acetylcholine

Answer 18

released by motor neurons at the neuromuscular junction causes contraction.

Question 19

flexors

Answer 19

bend or flex a joint

Question 20

extensors

Answer 20

straighten or extend

Question 21

Synergistic muscles

Answer 21

any two muscles whose contraction produces the same movement

Question 22

Antagonistic muscles

Answer 22

any two muscles that act in opposition

Question 23

Skeletal muscle types range from

Answer 23

Fast-twitch

Slow-twitch

Question 24

Fast-twitch

Answer 24

fibers produce fast contractions but fatigue rapidly

Question 25

Slow-twitch

Answer 25

fibers produce less vigorous contraction without fatigue

Question 26

Golgi Tendon Organs

Answer 26

Embedded in tendons (tendons connect muscle to bone)

Detect muscle tension

Question 27

Muscle Spindles

Answer 27

Embedded in muscle tissue
Detect changes in muscle length
Intrafusal muscle within each muscle spindle is innervated by its own intrafusal motor neuron.
Keeps tension on the middle, stretch-sensitive portion of the muscle spindle to keep it responsive to changes in the length of the extrafusal muscle

Question 28

Central pattern generator:

Answer 28

creates stereotypical movements

e.g., wing flapping in birds or “wet dog shake”

Question 29

A motor program:

Answer 29

refers to a fixed sequence of movements that is either learned or built into the nervous system
Once begun, the sequence is fixed from beginning to end
Automatic in the sense that thinking or talking about it interferes with the action
e.g., mouse grooming itself; yawning

Question 30

Response Chunking

Answer 30

Practice combines the central programs controlling individual response.

Question 31

Shifting Control to Lower Levels

Answer 31

Frees up higher levels to do more complex tasks

Permits greater speed

Question 32

The basal ganglia

Answer 32

is a group of large subcortical structures in the forebrain

Responsible for initiating an action not guided by a stimulus

Question 33

Basal ganglia Comprises the following structures

Answer 33

Caudate nucleus
Putamen
Globus pallidus

Question 34

How do we learn new motor skills?

Answer 34

• The learning of new skills requires multiple brain areas involved in the control of movement
• Basal ganglia are critical for learning motor skills, “automatic” behaviors, and new habits
  Example: driving a car
• Primary motor cortex: The pattern of activity becomes more consistent as a new skill is learned

Question 35

Movement Disorders

Answer 35

Parkinson’s Disease
Huntington’s Disease
Multiple Sclerosis

Question 36

Parkinson’s Disease

Answer 36

Characterized by muscle tremors, rigidity, slow movements, and difficulty initiating physical and mental activity
Symptoms also include depression, memory and reasoning deficits

Question 37

Immediate Cause of Parkinson’s

Answer 37

Caused by gradual and progressive death of neurons, especially in the substantia nigra
Substantia nigra sends dopamine-releasing axons to the caudate nucleus and putamen, exciting them

Question 38

Treatment of Parkinson’s Disease

Answer 38

The drug L-dopa is the primary treatment for Parkinson’s and is a precursor to dopamine that easily crosses the blood-brain barrier
Often ineffective and especially for those in the late stages of the disease
Does not prevent the continued loss of neurons
Enters other brain cells, producing unpleasant side effects

Question 39

Other Possible Treatments for Parkinson’s

Answer 39

Drugs that directly stimulate dopamine receptors
Implanting electrodes to stimulate areas deep in the brain
Experimental strategies such as:
Transplanting brain tissue of aborted fetuses
Implantation of stem cells that are programmed to produce large quantities of L-dopa

Question 40

Huntington’s Disease

Answer 40

Associated with gradual and extensive brain damage especially in the basal ganglia but also in the cerebral cortex

Question 41

Heredity and Presymptomatic Testing - huntingtons

Answer 41

Presymptomatic tests can identify with high accuracy who will develop the disease
Controlled by an autosomal dominant gene on chromosome #4
The higher the number of consecutive repeats of the combination C-A-G (cytosine, adenine, guanine), the more certain and earlier the person is to develop the disease

Question 42

Multiple sclerosis(MS)

Answer 42

• Anautoimmune disorder—a disorder in which the body’s immune system attacks part of the body, as if it were a foreign substance.
• A progressive disease that attacks the myelin of axons in the CNS.
• Typically attacks young people just as they are beginning their adult life.
• First, there are microscopic areas of degeneration on myelin sheaths but eventually damage to the myelin is so severe that the associated axons become dysfunctional and degenerate