10) Motor Disorders Flashcards
What are the major motor pathways?
Corticospinal, corticobulbar and extrapyramidal tracts
What is the function of the cerebellum?
Motor control and coordination
How is the cerebellum separated from the occipital and parietal lobes?
Tentorium cerebelli
How is the cerebellum separated from the pons?
4th ventricle
Describe the structure of the cerebellum?
Consists of vermis (midline) and two lateral hemispheres
How does the cerebellum communicate with brainstem?
Cerebellar puduncles:
Superior to midbrain
Middle to pons
Inferior to medulla
What would be the effect of a midline lesion in the cerebellum?
Truncal ataxia and abnormal gait
A 45 year old man has a left cerebellar hemisphere lesion, list the effects:
Ipsilateral signs
DANISH - dysdiadochokinesia, ataxia, nystagmus, intention tremor, scanning dysarthria, heel shin test positive/hypotonia
What is the function of the basal ganglia?
Stimulates motor activity in cerebral cortex
What are some structures in the basal ganglia?
Caudate, lentiform nucleus, substantia nigra
What neurotransmitter do the majority of neurones in the striatum use?
GABA
Describe the structure of the substantia nigra and the neurotransmitters used:
Made up of pigmented neurones with pars compacta dorsally and pars reticularis ventrally
Dopamine
What is the overall net effect of the basal ganglia direct and indirect pathways on the thalamus?
Thalamic stimulation of motor cortex
Describe the direct pathway in the basal ganglia:
PC of SN sends excitatory dopaminergic connections to putamen which inhibits the globus pallidus interna which would normally inhibit the thalamus
Describe the indirect pathway in the basal ganglia:
PC of SN sends inhibitory dopaminergic connections to putamen which inhibits inhibitory connections to globus pallidus externa which in turn inhibits connections to subthalamic nucleus. STN doesn’t activate PR of SN and GPI so less inhibition of thalamus
How do disorders of the basal ganglia present?
Abnormal motor control, altered posture, muscle tone affected, dyskinesia
What is Parkinson’s disease?
Chronic, progressive, movement disorder due to degeneration of substantia nigra causes deficiency in dopamine
What is the triad of symptoms in Parkinson’s disease?
Bradykinesia, tremor and rigidity
What are some other symptoms of Parkinson’s disease?
Hypophonia, reduced facial expression, micrographia, LB dementia, depression, shuffling gait, visual hallucination
Describe the features of Huntingdon’s disease:
Autosomal dominant, progressive neurodegenerative disorder
Cell loss in basal ganglia and cortex
What are some symptoms of Huntingdon’s disease?
Dystonia, in-coordination, cognitive decline, behavioural difficulty, chorea
What is the function of the vermis and lateral hemispheres of the cerebellum?
Vermis regulates trunk musculature
Lateral hemispheres regulate distal structures
What is dysdiadochokinesia?
Inability to perform and sustain a series of rapidly alternating muscle movements (typically flipping one hand rapidly in the palm of the other)
What is ataxia?
Gross incoordination of muscle movements. May be very unsteady on their feet towards the side of the lesion
What is nystagmus?
Repetitive, involuntary oscillation of the eyes
