Motor Disorders Flashcards
Where is the cerebellum located within the cranium?
Posterior cranial fossa
How is the cerebellum separated from the occipital and parietal lobes?
By the tentorium cerebelli
How is the cerebellum separated by the pons?
4th ventricle
The cerebellum consists of the _____ and two _________ ___________
Vermis
Lateral hemispheres
The Vermis regulates which structures?
Trunk musculature
Lateral cerebral hemispheres regulate which structures?
Distal structures i.e. limbs
Are tracts in the cerebellum contralateral or ipsilateral?
Ipsilateral
Which structure attaches the cerebellum to the midbrain?
Superior cerebellar peduncle
Which structure attaches the cerebellum to the pons?
Middle cerebellar peduncle
Which structure attaches the cerebellum to the medulla?
Inferior cerebellar peduncle
Midline cerebellar lesions can cause what clinical presentations?
Truncal ataxia
Abnormal gait
Extension of cerebellar midline lesions can cause what?
4th cranial nerve lesions
Ipsilateral arm tremors
Compression of 4th ventricle
Obstruction of CSF flow—> Hyrdocephalus
Do cerebellar lesions cause ipsilateral or contrlateral symptoms?
Ipsilateral symptoms
What are the 6 symptoms of cerebellar pathology?
Disdiadochokinesis - abnormal repetitive movement
Ataxia - abnormal movement
Intention tremor
Slurred speech
Hypotonia- decreased muscle tone compared to normal, floppy
“DANISH”
What is the name of the area of the brain known to be involved in motor function?
Basal Ganglia
Name three important overall structures of the basal ganglia.
Caudate
Lentiform nucleus
Substantia nigra
The lentiform nucleus is made up of what?
Putamen
Globus pallidus externa
Blobus pallidus interna
Substantia nigra can be separated into which two parts?
How do they differ?
Pars compacta - dorsal, dopaminergic nerurones
Pars reticularis - ventral
Output of the basal ganglia is to the cerebral cortex via _________.
The thalamus
The caudate nucleus and the putamen make up what?
Striatum
What is the overall net effect of direct and indirect pathways in the basal glanglia with regard to the motor cortex.
Thalamic stimulation of the motor cortex
Disorders will present in the same or different side of the body to the affected basal ganglia?
Same side as the abnormal basal ganglia
What 4 features might imply disorders of the basal ganglia?
Abnormal motor control
Altered posture
Muscle tone
Dyskinesia
What is Parkinson’s disease?
How is the disease characterised (triad of features)?
Chronic, progressive movement disorder characterised by a triad of bradykinesia, tremor and rigidity
Parkinson’s disease is caused by what?
Degeneration of substantia nigra pars compacta which causes deficiency in dopamine production
Using reference to both the direct and the indirect pathways, explain why Parkinson’s disease presents as it does when the substantia nigra pars compacta is degenerated.
Without dopamine, the direct pathway is stimulatory and therefore inhibits the thalamus—> Causes bradykinesia
Without dopamine, the indirect pathway is inhibitory and therefore—> Further causes bradykinesia
Besides the three cardinal signs, what are some other associated features of Parkinson’s disease
Hypophonia
Reduced facial expression
Micrographia
Dementia
Depression
What is Huntington’s disease?
At what age does it usually present?
An autosomal, dominant, progressive disorder
Associated with cell loss within the basal ganglia and cortex 30-50 years
Give some defining symptoms of Huntington’s disease.
Chorea - abnormal, jerky movements of the body
Dystonia - repetitive muscle cramping
Incoordination
Cognitive decline
Behavioural difficulties
Describe the pathogenesis of Huntington’s disease.
Loss off GABAergic neurones from the putamen of the basal ganglia.
Lose inhibiton of globus pallidus externa which in turn leads to less inhibtion of the subthalamic nucleus —> less stimulation of the globus pallidus interna.
The globus pallidus interna is usually responsible for inhibition of the thalamus, loss of this inhibition.
This explains the excessive, jerky, uncoordinated movements.
The cerebellum can be divided into how many functional lobes?
3
- Anterior
- Posterior
- Flocculonodular
Give some examples of conditions that may cause cerebellar signs.
Posterior fossa tumour
Alcohol
MS
Trauma
Rare
Inherited
Epilepsy medication
Stroke
“PASTRIES”
