motor function Flashcards
Where do the corticospinal and corticobulbar tract arise from?
corticospinal- primary motor cortex
corticobulbar- somatosensory cortex
Describe the pathway of the corticospinal tract?
Upper motor neurons in the brain go to cerebral peduncles, then go into pyramids where they swap sides. lateral corticospinal tract goes to limbs and anterior goes to trunk
What are the extrapyramidal tracts and what do they each do?
Vestibulospinal- stabilises head during body and eye movements
Reticulospinal-controls muscle tone
Tectospinal-orientates head and neck during eye movements
Rubrospinal-taken over by corticospinal tract
What are the negative and positive signs of an upper motor neuron lesion?
Positive- hyperreflexia, spasticity, clonus (involuntary muscle contraction), babinskis sign
Negative- paresis, paralysis
what are the signs of a lower motor neuron lesion?
Weakness
hypotonia
hyporeflexia
muscle atrophy
fasciculations
fibrillations
= (both of these are muscle twitches, but fasciculations are much bigger)
What is motor neurone disease? How does it present?
neurodegenerative disorder of the motor system
Presentation:
upper motor neuron signs: spasticity, babinskis sign, dysarthria (inability to speak due to muscles) dysphagia
lower motor neuron signs: tongue wasting, nasal speech (sounds like a blocked nose when you speak) weakness, fasciculations
What is Parkinson’s disease and how does it present?
Its a degeneration of dopaminergic neurons originating from the substantia nigra
Presentations: Bradykinesia, hypomimic, Akinesia, Rigidity, Tremor at rest
FREEZING GAIT
TREMOR AT REST
What is Hungtington’s disease and how does it present?
What is the sequence of body parts affected?
Its a degeneration of GABAnergic neurons (inhibitory) originating from the striatum (caudate + putamen)
Presentation: Choreic movements, rapid jerky movements starting at hands and face followed by rest of body, dysphagia, dementia
What is Ballism and how does it present?
A stroke affecting the subthalamic nucleus
Presentations: Tingling of extremities, contralateral symptoms, involuntary movements of limbs
What is the function of the cerebellum?
What are the 3 parts of the cerebellum, what do they do and how does damage to each of them present?
Coordinates movement and balance
Vestibulocerebellum- regulates gait, posture and equilibrium. damage presents as gait ataxia (drunken gait) and tendency to fall TUMOUR
Spinocerebellum- coordinates speech and muscle tone. damage presents as unsteady gait and wide stance ALCOHOL
Cerebrocerebellum- coordinates skilled movements and cognitive function and language. damage presents in arms and skilled movements and speech (slurred speech) DYSMETRIA
What is a motor unit?
the term used to refer to a motor neuron and the muscle fibres it innervates
What are the types of motor units and which one exerts the most force?
Slow
Fast fatiguable- this one exerts the most initial force
Fast fatigue resistant
How is muscle force regulated?
Recruitment- smaller motor units are fired up first allowing for a controlled firing rate
Rate coding- different units fire at different frequencies
can motor units change properties and if so which ones and how?
fast fatiguable can change to fast fatigue resistant through training
slow to fast can happen via spinal cord injuries or severe deconditioning (spacemen)
ageing causes loss of fast muscle units
What is a reflex?
an automatic movement that does not use the CNS or conscious part of CNS
what is Babinskis sign?
When is this normal?
sole of foot is stimulated by stimulus, toe should curl downwards
if toe curls upwards, this is a positive babinksis sign (in infants its normal)
