Motor Control

Question 1

What is hierarchical organisation?

Answer 1

Higher orders do higher level of tasks which are more complicated and lower orders do lower tasks

Question 2

What is functional segregation?

Answer 2

Motor system organised in a number of different areas that control different conckecst of movement

Question 3

What are the pyramidal tracts and why are they called pyramidal tracts?

Answer 3

Pass through the pyramids of the medulla

• Corticospinal
• Corticobulbar

Go from motor cortex to the spinal cord or cranial nerve nuclei in brainstem

Question 4

What are the Extrapyramindal tracts?

Answer 4

Do not pass through the pyramids of medulla

• Vestibulospinal
• Tectospinal
• Reticulospinal
• Rubrospinal

Brainstem nuclei to spinal cord

Question 5

What does the primary motor cortex control?

Answer 5

Controls fine, discrete, precise voluntary movements

Descending signals to execute movements

Question 6

What are premotor area control?

Answer 6

Involved in planning movements

Externally cued movement e.g. seeing and apple and reaching for it

Question 7

What does the supplementary motor area do?

Answer 7

Planning complex movements which are internally cued e.g. speech

• becomes active prior to voluntary movement

Question 8

What percentage of fibres from corticospinal tract is responsible for trunk muscles?

Answer 8

10-15% uncrossed fibres = anterior corticospinal tract

Question 9

What do the motor nerves from the corticobulbar tract do?

Answer 9

Synapse with brainstem cranial nerve nuclei

Question 10

What is the corticobulbar tract responsible for?

Answer 10

principle motor pathway for voluntary movements of face + neck

Question 11

What does vestibulospinal tract control?

Answer 11

head movement with eye movement coordination
Stablise head during body movements

postural adjusting

Question 12

What does reticulospinal tract control?

Answer 12

arises from medulla and pons

changes muscle tone with voluntary movement
+
postural stability

Question 13

What does the tectospinal tract control?

Answer 13

arises from superior colliculus of midbrain

head and neck orientation during eye movements

Question 14

What does the rubrospinal tract control?

Answer 14

Arises from red nucleus of midbrain

mainly taken over by corticobulbar tract

Innervate lower motor nuerones of flexors of upper limb

Question 15

What negative signs are seen with upper motor neuron lesions? (3)

Answer 15

Loss of : voluntary movement

Paresis : graded weakness of movements

Paralysis : complete loss of voluntary muscle activity = plegia

Question 16

What are the positive signs seen with upper motor nueron tract? (4)

Answer 16

- increased function abnormally
Spasticity = increased muscle tone
- Hyper-reflexia
- Clonus
- Babinski's sign

Question 17

Why is increased motor function seen in upper motor neurone lesions?

Answer 17

Less descending inhibition inputs

Question 18

What is clonus? Why is this relevent?

Answer 18

Abnormal oscillatory muscle contraction :

seen in upper motor neurone lesions

Question 19

What is Apraxia?

Answer 19

A consequence of U.M.N.L

disorder of skileld movements

Meaning px will not have paralysis but lost information about how to perform skilled movements

Question 20

What are common causes of apraxia?

Answer 20

Stroke and dementia

Question 21

What symptoms and signs are seen in lower motor neurone lesions? (6)

Answer 21

• Weakness
• Hypotonia
• Hyporeflexia
• Muscle atrophy
• Fasciculations
• Fibrillations

Question 22

Why do fasciculations result in a twitch?

Answer 22

Damaged motor units produce spontaneous APs at NMJ = twitch

Question 23

What are fibrillations and how can we record these?

Answer 23

Spontaneous twitching of individual muscle fibres

• use needle electromyography examination

Question 24

What is Motor neuron disease - MND and what is it also known as?

Answer 24

Progessive neurodegenerative disorder of motor system

ALS = amyotrophic lateral sclerosis

Affects both upper and lower neurones

Can cause a spectrum of disorders affecting intercostal muscles, lower and upper limb muscles, tongue

Question 25

Why can ALS cause death?

Answer 25

Over time it gets worse | - affects respiration due to muscles

Question 26

What are the UMN signs in ALS/MND?

Answer 26

- Spasticity (increased tone of limbs and tongue) - Brisk limbs and jaw reflexes - Babinski’s sign - Loss of dexterity - Dysarthria (difficulty speaking) - Dysphagia (difficulty swallowing)

Question 27

What are the LMN signs in ALS/MND?

Answer 27

- Weakness - Muscle wasting - Tongue fasciculations and wasting - Nasal speech - Dysphagia

Question 28

What structures are found in the basal ganglia?

Answer 28

- Caudate nucleus - Lentiform nucleus ( made of putamen and external pallidus ) *together caudate and putamen are known as striatum - Nucleus accubens - Subthalamic nuclei - Substantia nigra (midbrain) - ventral pallidum, claustrum, nucleus basalis ( of meynert )

Question 29

What is the function of the basal ganglia?

Answer 29

Make the decision to move Elaborating associated movements e.g. swinging arms when walking, changing facial expressions to match emotions Suppressing unwanted movements Performing movements in order

Question 30

What abbreviation is used to remember the parts of the basal ganglia?

Answer 30

``` C - caudate nucelus P - putamen G - external Globus pallidus T - Thalamus Acc - nucelus accumbens Am - Amygdala Ac - Anterior commisure ```

Question 31

Why are there so many complications with the basal ganglia?

Answer 31

A big circulitry with many input and output paths (slide 20)

Question 32

What is Parkinson's caused by?

Answer 32

Degeneration of the dopamingergic nuerones that orginate in the substania niagra and project to the striatum

Question 33

What are the signs and symptoms of parkinsons?

Answer 33

Bradykinesia - slowness of (small) movements (doing up buttons, handling a knife) Hypomimic face - expressionless, mask-like (absence of movements that normally animate the face) Akinesia - difficulty in the initiation of movements because cannot initiate movements internally Rigidity - muscle tone increase, causing resistance to externally imposed joint movements Tremor at rest - 4-7 Hz, starts in one hand (“pill-rolling tremor”); with time spreads to other parts of the body

Question 34

What is Huntingtons disease caused by?

Answer 34

Denegeration of GABAergic neurons in the striatum, caudate and putamen It is a chromosome 5 authosomal dominent CAG repeat disorder

Question 35

What are the signs and symptoms of Huntingons disease?

Answer 35

Choreic movements (chorea - dance) rapid jerky involuntary movements of the body; hands and face affected first; then legs and rest of body Speech impairment Difficulty swallowing Unsteady gait Later stages, cognitive decline and dementia

Question 36

What is Ballism?

Answer 36

Sudden uncontrolled flinging of the extremties Symptoms occur contralaterally

Question 37

What is Ballism caused by?

Answer 37

usually from stroke affecting subthalamic nucelus

Question 38

Where is the cerebellum located?

Answer 38

Posterior cranial fossa Sepreated from cerebrum above by tentorium cerebelli It is the coordinator and predictor of movement

Question 39

What is the vestibulocerebellum ?

Answer 39

Regulation of gait, posture and equilibrium | Coordination of head movements with eye movements

Question 40

What does a damage such as tumour affecting the vestibulocerebellum do to the px?

Answer 40

Damage (tumour) causes syndrome similar to vestibular disease leading to gait ataxia and tendency to fall (even when patient sitting and eyes open

Question 41

What is the spinocerebellum?

Answer 41

Coordination of speech Adjustment of muscle tone Coordination of limb movements

Question 42

What does damage to the spinocerebellum do to a px?

Answer 42

affects mainly legs, causes abnormal gait and stance (wide-based)

Question 43

Why may the spinocerebellum be damaged?

Answer 43

Degeneration and atrophy associated with chronic alcoholism

Question 44

What does the cerebrocerebellum do?

Answer 44

Coordination of skilled movements Cognitive function, attention, processing of language Emotional control

Question 45

What does damage to the cerebroccerebellum do to the px?

Answer 45

affects mainly arms/skilled coordinated movements (tremor) and speech

Question 46

What are the mains signs of cerebellar dysfunction? (5)

Answer 46

These are apparanet only on movement: Ataxia General impairments in movement coordination and accuracy. Disturbances of posture or gait: wide-based, staggering (“drunken”) gait Dysmetria Inappropriate force and distance for target-directed movements (knocking over a cup rather than grabbing it) Intention tremor Increasingly oscillatory trajectory of a limb in a target-directed movement (nose-finger tracking) Dysdiadochokinesia Inability to perform rapidly alternating movements (rapidly pronating and supinating hands and forearms) Scanning speech Staccato, due to impaired coordination of speech muscles