Voluntary Movement

Question 1

what are the three types of movement

Answer 1

involuntary actions
semi automatic actions
voluntary actions

Question 2

what are semi automatic actions

Answer 2

these are actions that are voluntary and we could adapt but we usually dont even think about them, like walking, chewing and breathing.
they are usually repeated movement sequences and appear stereotyped but could change them if we wanted to

Question 3

what drives semi automatic actions

Answer 3

central pattern generators, which are collections of neurons specific to the action they initiate or maintain

Question 4

what is the typical nerve cell structure

Answer 4

• cell body that houses the nucleus. from the cell body there are projections of the cell extension called dendrites that act as antennas to increae the surface area of the cell itself to allow it to receive input from various other cells to allow it to input the information
  they are innervating other distinct circuits and will not be found in isolation

Question 5

what does the output of CGPs do

Answer 5

innervate an effector organ which will allow the individual to repond in a particular way to their environment

Question 6

what are central pattern generators

Answer 6

collections of neurons with a rhythmic output that will influence motor patterns of particular muscle groups

Question 7

why is there reflex feedback in effector organs

Answer 7

this allows for the CGP ouput to be monitoried at all times to make sure it is relevant to the needs of that environment

Question 8

describe sensory feedback sysems

Answer 8

this is where the environment can influence the CGP directly or indirectly through innervation of higher control neurons which in turn feedback to the CGP

Question 9

what is the central feedback loop of the CGP

Answer 9

higher cortical regions can modifty the CGP using a voluntary response

Question 10

what are the different feedback loops associated with CGPs

Answer 10

• reflex feedback
• central feedback loop
• sensory feedback system

Question 11

what are voluntary actions

Answer 11

self initiated actions that are goal directed and learned. they can be adapted and improved with practice

Question 12

where is the primary sensory cortex

Answer 12

posterior to the central sulcus

Question 13

where is the motor cortex

Answer 13

anterior to the central cortex

Question 14

describe the motor homunculus

Answer 14

areas in the homunculus that correspond to the face and hands are large because the motor units for these areas are small and highly packed to allow precision in movement.
limbs have a smaller area because the muscles are large and produce larger, less concise movements

Question 15

what are the two descending pathways for voluntary movement

Answer 15

corticospinal and corticobulbar

Question 16

describe the neuronal element of the descending motor pathways for voluntary movment

Answer 16

• only two
• upper neuron with cell bodies in motor cortex that has an axon that descends through the cortex to the brain stem to innervate muscle in the head and neck or to the spinal cord for the body
• lower neuron sends axon out to peripheral nerve to innervate the muscle for the actual contraction for movement

Question 17

what are the three regions of white matter

Answer 17

dorsal funiculus
lateral funiculus
ventral funiculus

Question 18

which funiculus are important when looking at descending motor pathways

Answer 18

the dorsolateral funiculus and the ventromedial funiculus

Question 19

what is the motor innervation of trigeminal

Answer 19

muscle of mastication

Question 20

what is the motor innervation of the facial nerve

Answer 20

muscle of facial expression

Question 21

what is the motor control of the vagus nerve

Answer 21

soft palate
larynx
pharynx

Question 22

what is the motor innervation of the hypoglossal

Answer 22

extrinsic muscles of the tongue

Question 23

describe the corticobulbar pathway

Answer 23

this is the pathway for the recruitment of lower motor neurons comprising cranial nerves.
cortical portion is the location of the upper neuron and the bulbar is the relative position of the motor nuclei throughout the brainstem for each corresponding cranial nerve

Question 24

where do cell bodies originate for the corticobulbar pathway

Answer 24

the motor cortex, and their axon goes down through the internal capsule through the basis pedunculi in the midbrain to give off branches that innervate the distinct motor neuron groups

Question 25

where are the cell bodies for the trigeminal motor neuron bodies

Answer 25

trigeminal nucleus in the pons

Question 26

what is the facial nerve cell body in the brainstem

Answer 26

the facial motor nucleus at the pontomedullary junction

Question 27

where is the cell body of the vagus nerve

Answer 27

nucleus ambiguus in the medulla

Question 28

where is the cell body of the hypoglossal nerve

Answer 28

nucleus ambiguus

Question 29

how can we carry out simulataneous bilateral muscle contraction

Answer 29

the projections of lower motor neurons bifurcate to inneravate both sides of the neuroaxis to carry out the contraction on both sides

Question 30

how does the spinocortical pathway differ from the corticobulbar pathway

Answer 30

axons project much further as they go own the spinal cord the axons cross over to the other side of the spinal cord

Question 31

what is the pyramidal dessucation

Answer 31

this is where majority of the axons in the spinocortical pathway will cross over to the other side of the neuroaxis at the level of the medulla

Question 32

how many axons will remain on the same side of the neuroaxis at the pyramidal dessucation, and where do they cross over instead

Answer 32

15%, and they will only cross over once they reach the level of the motor neurons that they are due to innervate

Question 33

which descending motor neurons in the spinocortical pathway are found in the lateral corticospinal tract

Answer 33

those that crossed at the pyramidal dessucation

Question 34

which descending motor neurons in the spinocortical pathway are found in the anterior corticospinal tract

Answer 34

those that are confined to the same side of the neuroaxis until they cross over at their own level

Question 35

which region of the spinal cord houses the lateral corticospinal tract

Answer 35

the dorsolateral funiculus

Question 36

which region of the spinal cord houses the anterior corticospinal tract

Answer 36

the ventromedial funiculus

Question 37

which pathways to motor neurons originate from the opposite side of the brain

Answer 37

the pathways to motor neurons controlling distal muscles originate from the opposite side of the brain.

Question 38

what are distal muscles

Answer 38

hands feet lower half of the face tongue

Question 39

what is the command of the gag reflex

Answer 39

bilateral descending cortical demand

Question 40

what happens if the lower motor neurons are damaged

Answer 40

we will not be able to initiate any movement at all because the final output to muscles are lost

Question 41

describe bells palsy

Answer 41

they lose capacity to engage and contract muscles of facial expression some think this could be due to inflammation dissipates within two weeks with no long lasting effect

Question 42

what is the purpose of additional descending motor projections

Answer 42

they serve to coordinate movement, help maintain posture and balance, and they help to integrate the actions of several muscles

Question 43

where do additional descending motor projections arise from

Answer 43

various areas of the cerebrum and brainstem like the basal ganglia, cerebellum and brainstem

Question 44

describe basal ganglia

Answer 44

these are comprised of several interconnected subcortical nuclei that link to the cerebral cortex via feedback loops

Question 45

what does the basal ganglia do

Answer 45

influence and regulates output from the motor cortex acts to initiate actions and switch from one action to another

Question 46

what structure links the two hemispheres of the brain

Answer 46

corpus callosum

Question 47

what can allow for the identification of the basal ganglia

Answer 47

the ventricles and associated bundles of white matter

Question 48

where is the body of the caudate nucleus found

Answer 48

the lateral protrusion at the lateral aspect of the lateral ventricle

Question 49

where is the putamen

Answer 49

the internal capsule of white matter, where there is a cluster of cells forming a grey matter

Question 50

where is the globus pallidus

Answer 50

medial to the putamen

Question 51

where is the thalamus

Answer 51

protrusion in the lateral aspect of the third ventricle

Question 52

where is the substantia nigra

Answer 52

speckled grey matter posterior to the thalamus

Question 53

what are the components of the basal ganglia

Answer 53

- body of caudate nucleus - putamen - globus pallidus - thalamus - substantia nigra

Question 54

what makes up the corpus striatum

Answer 54

the caudate nucleus putamen globus pallidus

Question 55

what makes up the sub thalamic nuclei

Answer 55

the thalamus

Question 56

what are the three action selection centres formed from the basal ganglia

Answer 56

corpus striatum subthalamic nuclei substantia nigra

Question 57

which region of the brain is affected by parkinsons disease

Answer 57

the substantia nigra

Question 58

which region of the brain is affected by huntingtons disease

Answer 58

the corpus striatum

Question 59

what causes parkinsons

Answer 59

dopamine deficiency in the substantia nigra

Question 60

describe parkinsons disease

Answer 60

- hypokinetic disorder leading to reduced movements - leads to a resting tremor due to paralysis agitans - poverty of movement - mask like face - difficulty in initiating movements

Question 61

what is the actual reason for the symptoms from parkinsons

Answer 61

deterioration of nerve cells in the substantia nigra

Question 62

describe huntingtons disease

Answer 62

hyperkinetic disorder leading to excessive and uncontrolled movements happens due to an imbalance in neurotransmitter (decreased GABA levels) in the striatum

Question 63

describe the cerebellum

Answer 63

this region is important for coordinating movements and regulates actions of antagonistic muscle groups it is important in maintaining balance and receives input from proprioceptors acts to compare the actual performance with what is intended

Question 64

where is the cerebellum

Answer 64

at the back of the brain behind the brainstem at the pons and fourth ventricle occipital lobe found behind it

Question 65

describe voluntary actions muscle usage

Answer 65

it is very rare for only one set of muscles to be involved in an action action by one set of muscles are often accompanied by actions of other muscles therefore they are coordinated to ensure posture and balance are maintained

Question 66

what happens to maintain posture if we lean forward and stretch our calf muscles

Answer 66

the stretch reflexes that are mediated by muscle spindles will allow for contraction and this will return our posture back to normal

Question 67

what maintains upright posture

Answer 67

series of small correcting actions that keep the head in position with the body's centre of gravity

Question 68

what initiates and refines motor output

Answer 68

initiated from activity from the motor cortex refined from regions of the associated cortex and subcortical areas