Voluntary Movement

Question 1

Describe voluntary actions

Answer 1

Self-initiated
Purposeful - goal directed
Learned
Improved with practice
Adaptable

Question 2

What are semi-automatic actions

Answer 2

Voluntary - but you don’t have to think about them

Often they are repeated movement sequences

Question 3

Give examples of semi-automatic actions

Answer 3

Walking, breathing, chewing

Question 4

What are CPGs

Answer 4

Central pattern generators
Initiate and maintain a specific action
May be synchronised eg - swinging arms and legs

Question 5

Why are feedback loops important in CGPs

Answer 5

Constant feedback of info ensures that the reaction we have to our environment is appropriate

Question 6

Describe the corticobulbar pathway

Answer 6

Arises from the primary motor cortex
Fibres converge and pass through the internal capsule to the brain stem
The neurons terminate on the motor nucleu of the cranial nerves where they synapse with lower motor neurons which carry the motor signals to the muscles of the face\

Question 7

What is an important feature of the corticobulbar pathway

Answer 7

Often axons bifurcate meaning it can recruit muscles on both sides of the body allowing synchronised muscle contraction

Question 8

Describe the corticospinal pathway

Answer 8

Originate in the motor cortex and axons project right through the brainstem to the pyramids in the medulla oblongata
Here the axons split, 85% cross over to the opposite side and project down the spinal cord to innervates their appropriate lower motor groups

Question 9

What is the lateral corticospinal pathway

Answer 9

The 85% of the axons that cross over to the other side of the body

Question 10

What is the anterior corticospinal pathway

Answer 10

The 15% of the axons which do not cross over to the other side of the body

Question 11

What happens if a descending pathway is damaged

Answer 11

Damage (lesions) to pathway impairs their normal functions

Question 12

What is a palsy

Answer 12

Paralysis to motor pathways caused by lesions

Question 13

What are some causes of paralysis in lower motor neurons

Answer 13

Damage to LMN
Nerve injury
Viral infection (polio)

Question 14

Describe paralysis in upper motor neurons

Answer 14

Damage in corticospinal and corticobulbar tracts
Damage to UMN
CNS injury (stroke)

Question 15

What are some results of paralysis in lower motor neurons

Answer 15

No reflexes
No voluntary movement
Muscle atrophy

Question 16

What are some results of paralysis in upper motor neurons

Answer 16

No voluntary movement

Reflexes present but exaggerated

Question 17

What are additional descending motor projections

Answer 17

Arise from various areas of the cerebrum and brainstem

Basal ganglia, cerebellum and brainstem

Question 18

What is the function of additional descending motor projections

Answer 18

Serve to co-ordinate movements
Help maintain posture/balance
Help integrate actions of several muscles

Question 19

What is the basal ganglia

Answer 19

Comprised of several interconnected sub-cortica nuclei
Link to cerebral cortex via feedback loops
Influence/regulate output from the motor cortex
Act to initiate actions and to switch from one action to another

Question 20

What makes up the basal ganglia

Answer 20

Body of caudate nucleus
Putamen
Globes Pallidus
Thalamus
Substantial Nigra
Corpus callosum

Question 21

What is the corpus callosum

Answer 21

Allows the two sides of the Brian to communicate

Question 22

What are the action selection centres

Answer 22

Corpus striatum
Sub-thalamus nuclei
Substantial nigra

Question 23

What makes up the corpus striatum

Answer 23

Caudate nucleus
Putamen
Globes pallidus

Question 24

What does damage/disease to the substantial nigra result in

Answer 24

Parkinson’s disease

Question 25

What does damage/disease to the corpus striatum result in

Answer 25

Huntington’s disease

Question 26

Give examples of some basal ganglia disorders

Answer 26

Parkinson’s disease

Huntington’s disease (Chorea)

Question 27

What do patients with Parkinson’s disease usually present with

Answer 27

Hypokinetic disorder so decreased movements
Resting tremor
Poverty of movements
Mask-like face
Difficulty initiating movements
Domapine deficiency in substantial nigra

Question 28

What do patients with Huntington’s disease usually present with

Answer 28

Hyperkinetic disorder so increased movements
Excessive, uncontrolled movements
Imbalance of neurotransmitter
Decreased levels of GABA

Question 29

What are the functions of the cerebellum

Answer 29

Co-ordinating movements
Regulates actions of antagonistic muscle groups
Important in maintaining balance - receives inputs from proprioceptors
Acts to compare actual performance with what is intended

Question 30

Describe cerebellum disorders

Answer 30

Characterised by loss of co-ordination
Unsteady gait (ataxia)
Imprecise actions
Inability to co-ordinate altering contractions of antagonistic muscles
Intention tremor (resting tremor in Parkinson’s)

Question 31

Why are actions usually co-iordinated

Answer 31

To ensure that posture/balance is maintained

Question 32

Describe how posture is maintained

Answer 32

Forward sway stretches muscles in the back of the leg
Upright posture is maintained by a series of smaller correcting actions
These help keep the position of the head inline with gravity