Cortical Motor Control Flashcards
What is hierarchial organisation?
Areas of higher order are involved in more complex tasks
What are the 2 types of descending tracts?
Pyramidal
Non-pyramidal
What are the 2 pyramidal tracts?
Corticospinal
Corticobulbar
What are the 4 non pyramidal tracts
Tectospinal
Rubrospinal
Reticulospinal
Vestibulospinal
What are pyramidal tracts for?
Voluntary movement of the head and face
What are non-pyramidal tracts for?
Non voluntary movements for balance locomotion etc
Describe how pyramidal tracts decend
Through pyramidal cells pf medulla
From the motor cortex to the spinal chord or cranial nerve nuclei in the brainstem
Describe how non-pyramidal tracts decend
Not through the pyramidal cells of the medulla
From brainstem nuclei to spinal chord
What is the vestibulospinal tract for?
Stabilises head during body movements
Coordinates head movements with eye movements
What is the reticulospinal tract for?
Changes muscle tone associated with voluntary movement and postural stability
What is the rubrospinal tract for?
Innervate lower motor neurons of flexors of the upper limb
What is the tectospinal tract for?
Orientation of the head and neck during eye movements
What is the role of the primary motor cortex?
Controls fine, discrete, precise voluntary movements
What is the role of the supplementary area?
Involved in planning complex movements (e.g. internally cued, speech), is active prior to voluntary movement
What is the role of the premotor area?
Involved in planning externally cued movements
Where does the corticospinal tract decussate?
Pyramidal cells of the medulla
What symptoms are associated with an upper motor neuron lesion?
Loss of voluntary motor function Graded weakness of movement Paralysis Increased abnormal motor function (due to loss if inhibition) Increased muscle tone Hyper reflexia Babinskis sign Apraxia
What is Babinski’s sign?
Big toe curls upwards instead of down when sole of the foot is stroked (note this is normal for babies but in anyone older they should curl down)
What is apraxia?
Patients have lost information about how to perform skilled movements.
What symptoms are associated with a lower motor neuron lesion?
Weakness Hypotonia Hyporeflexia Muscle atrophy Fasciculations Fibrillations
In MND, what upper motor neuron lesion symptoms do patients have?
Spasticity (increased tone of limbs and tongue) Brisk limbs and jaw reflexes Babinski’s sign Loss of dexterity Dysarthria (difficulty speaking) Dysphagia (difficulty swallowing)
In MND, what lower motor neuron lesion symptoms do patients have?
Weakness Muscle wasting Tongue fasciculations and wasting Nasal speech Dysphagia
Where is the basal ganglia located?
Caudate nucleus
What are the functions of the basal ganglia?
Decision to move, elaborating associated movements, moderating and coordinating movement, performing movements in order
What happens in Parkinsons?
Degeneration of the dopaminergic neurons that originate in the substantia nigra and project to the striatum
How does Parkinson’s present?
Bradykinesia Hyponomic (expressionless face) Akinesia Rigidity Tremor at rest (starts in one hand)
What happens in Huntingtons?
Degeneration of GABAergic neurons in the striatum, caudate and then putamen due to chromosome 4 CAG repeat (autonomic dominant)
How does Huntington’s present?
Choreic movements
Speech impairment
Dysphagia
Unsteady gait
What is ballism?
Sudden flinging of extremities, happens contralaterally
Why does ballism arise?
Due to stroke in subthalamic nucleus
Where is the cerebellum located?
Posterior cranial fossa
What is the role of the cerebellum?
Coordinator and predictor of movements
What are the 3 subparts of the cerebellum?
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
How does damage to the vestibulocerebellum usually occour?
Tumor
How does damage to the spinocerebellum usually occour?
Chronic alcoholism causes degeneration and atrophy
How does damage to the vestibulocerebellum present?
Gait ataxia and tendency to fall
How does damage to the spinocerebellum present?
Affects mainly legs, causes abnormal gait and stance
How does damage to the cerebrocerebellum present?
Affects mainly arms/skilled coordinated movements (tremor) and speech
What are the main signs of cerebellar dysfunction? When do they present?
Only apparent on movement: Ataxia Dysmetria Intention tremor Dysdiadochokinesia Scanning speech
