6. Movement disorders

Question 1

what is the source of dopamine in the midbrain?

Answer 1

substantia nigra pars compacta

Question 2

what is the striatum made of?

Answer 2

caudate nucleus and putamen

Question 3

what is the role of the striatum?

Answer 3

receives input from the substancia nigra pars compacta and the cortex

Question 4

what are the two parts of the globus pallidus?

Answer 4

internal and external segment

Question 5

what is the lentiform nucleus formed from?

Answer 5

putamen and globus pallidus

Question 6

what is the basal ganglia made up of?

Answer 6

SNc, striatum, caudate nucleus, putamen, globus pallidus, lentiform nucleus, subthalamic nucleus

Question 7

what is the role of the basal ganglia?

Answer 7

communicates with the motor cortex via the thalamus. increasing thalamic activity causes increased cortical activity and vice versa. role in reinforcing appropriate movements and removing inappropriate

Question 8

what do direct pathways do?

Answer 8

reinforces appropriate movements so excites the motor cortex

Question 9

what do indirect pathways do?

Answer 9

edits out inappropriate movements so inhibitory to motor cortex

Question 10

how does dopamine facilitate movement?

Answer 10

exciting the motor cortex - excites direct pathway by stimulating D1 receptors on striatal neurones taking part in direct pathway, inhibits indirect by activating inhibitory D2 receptors

Question 11

what does the basal ganglia regulate?

Answer 11

ipsilateral motor cortex

Question 12

what is parkinson’s disease caused by?

Answer 12

degeneration of dopaminergic neurones in the SNc

Question 13

what are the signs and symptoms of parkinson’s disease?

Answer 13

tremor (may be due to dysfunction of indirect pathway which would normally supress unwanted movements)
rigidity (lack of coordination between agonist and antagonists)
bradykinesia (due to loss of cortical excitation)
hypophonia (bradykinesia of larynx and tongue)
decreased facial movements (bradykinesia of face)
micrographia (bradykinesia in hands)
dementia (possible progression)
depression (as basal ganglia have role of in cognition and mood)

Question 14

what is the presentation of huntington’s chorea?

Answer 14

autosomal dominant
onset at 30-50
hyperkinetic features - increased movement as loss of inhibition on thalamus

Question 15

what is huntingtons caused by?

Answer 15

loss of inhibitory projections from striatum to GPe

Question 16

what are signs and symptoms of huntington’s chorea?

Answer 16

chorea (dance like movements due to increased motor cortex activation)
dystonia (uncomfortable contractions of agonists and antagonists leads to odd postures to over activity in muscle circuits and loss of coordination)
loss of coordination ^
cognitive decline and behaviour disturbances

Question 17

what is hemiballismus?

Answer 17

a rare disorder caused by damage to the subthalamic nucleus which normally inhibits the thalamus via GPi resulting in unilateral explosive (ballistic) movements

Question 18

what is a cause of hemibasillismus?

Answer 18

sub cortical stroke

Question 19

what is the cerebellum made of?

Answer 19

midline vermis and two laterally placed hemispheres

Question 20

what are the roles of the different parts of the cerebellum?

Answer 20

vermis - trunk

hemispheres - ipsilateral side of the body

Question 21

how does the cerebellum communicate with the rest of the CNS?

Answer 21

via the cerebellar peduncles:
superior cerebellar peduncles - midbrain
middle - pons
inferior - medulla

Question 22

what is a consequence of cerebellar tumours and why does this occur?

Answer 22

can cause hydrocephalus as it sits above the fourth ventricle

Question 23

what is the role of the cerebellum?

Answer 23

sequencing and coordination of movements by using sensory information and deciding upon the most appropriate sequence of movements to perform the action

Question 24

how do the cerebellum and basal ganglia work together?

Answer 24

basal ganglia decides the most appropriate movements and the cerebellum then sequences these

Question 25

what inputs and outputs does the cerebellum receive?

Answer 25

sensory inputs from the ipsilateral spinal cord and contralateral sensory cortices
outputs are to the contralateral motor cortex

Question 26

on what side would you get a cerebellar lesion presentation?

Answer 26

ipsilateral
its outputs are to contralateral mtoor cortex but then the due to the decussation of corticospinal pathway
https://www.getbodysmart.com/motor-system/pyramidal-tract-pathway
its a double crossing over

Question 27

what are the signs of cerebellar disease?

Answer 27

dydiadochokinesia (difficulty with rapidly alternating mvoemnts - sup to prone to sup to prone)
ataxia(unsteady gait due to difficulty sequencing lower limb muscle contractions and loss of unconscious proprioception from lower limbs)
nystagmus (flickering eye movements due to malcoordination of extra ocular muscles)
intention tremor (tremor gets worse as target approaches)
slurred speech - dysarthria due to malcoordination of laryngeal and tongue musculature
hypotonia