Motor System Disorders Flashcards
Where is the cerebellum located?
Posterior cranial fossa
What is the role of the cerebellum?
Motor control and coordination
How does the cerebellum communicate with the brainstem and cortex?
Superior = cerebellar peduncle attaches cerebellum to midbrain
Middle = cerebellar peduncle attaches cerebellum to pons
Inferior = cerebellar peduncle attaches cerebellum to medulla
Cerebellum communicates with the cortex via the thalamus
Outline the tracks of the cerebellum
Lateral cerebellar hemispheres regulate distal structures – limbs
Tracts are ipsilateral = ipsilateral symptoms
Explain how a lesion in the cerebellum can result in hydrocephalus
Extension of midline lesions can cause compression of the 4th ventricle
What is the function of the vermis?
Regulating trunk musculature
What do lesions in the vermis result in?
Truncal ataxia and abnormal gait
What occurs to the cerebellar tonsil when ICP raises?
If ICP increases the tonsil can herniate though foramen magnum = compression of medulla
Describe the symptoms of a cerebellar disease - DANISH
D = dysdiadochokinesis – impaired ability to perform rapid movements
A = ataxia – lack of voluntary coordination of muscle movements including gait
N = nystagmus – rapid eye movements when awake
I = intention tremor – finger nose point with tremor
S = slurred speech
H = hypotonia
What structures make up the basal ganglia?
Lentiform nucleus = putamen, globus pallidus external and internal
Caudate nucleus
Thalamus
Substantia nigra (2 parts: pars compacta, pars reticulata)
Subthalamic nucleus
What is the striatum?
Putamen + caudate nucleus
What are the layers of the lentiform nucleus?
Putamen (lateral)
Globus pallidus external
Globas pallidus internal (medial)
What is the role of the basal ganglia?
Stimulate the motor cortex
In the absence of dopamine what does the direct pathway result in?
Stim the thalamus
In the absence of dopamine what does the indirect pathway result in?
Inhib the thalamus
What is the overall effect of dopamine in the direct and indirect pathway?
Motor cortex stimulation via the thalamus
Where are the dopaminergic neurones found that deteriorate in parkinsons?
Substantia nigra – pars compacta
How can dopamine cause both an excitatory and inhibitory effect on the putamen?
Diff sub types of receptors lead to either excitatory or inhibitory results
What are the symptoms of basal ganglia disorder?
Abnormal motor control
Altered posture
Affects muscle tone
Dyskinesia
Describe Parkinson’s
Degeneration of substantia nigra causes deficiency of dopamine
Chronic, progressive movement disorder
Triad of bradykinesia, tremor and rigidity
What are the cardinal features of parkinsons?
Tremor-Resting – on movement the tremor disappears
Bradykinesia – slow movement
Hypertonia- Rigidity
What are the associated features of Parkinson’s?
Hypophonia
Reduced facial expression
Micrographia
Dementia
Depression
What is Huntington’s disease?
Autosomal-dominant, progressive neurodegenerative disorder
Loss of GABA neurones within the Striatum =
Loss of the indirect pathway = over-stimulation of the motor cortex = chorea
What are the symptoms of Huntington’s disease?
Chorea
Dystonia
Incoordination
Cognitive decline
Behavioural difficulties
What is Hemiballismus?
Dysfunction contralateral subthalamic nuclei damage = over-stim of motor cortex
Results in unilateral abnormal movement
Often secondary to sub-cortical stroke
