The spinal cord contains CPG's that can produce locomotor patterns without descending influence.
What are the three brain centres that can be imposed on SC circuitry?
Motor cortex
Visual cortex
Cerebellum
Cerebral cortex
Parietal cortex
Lateral pathways are associated with control of?
Distal flexor muscles
Proximal/axial extensors to control posture
Ventromedial pathways control what?
Ventromedial pathways are under control of the brainstem, whereas lateral pathways execute voluntary actions.
Name the lateral motor pathways
Corticospinal
Rubrospinal
Reticulospinal
Tectospinal
Vestibulospinal
Name the ventromedial motor pathways
Where does the vestibulospinal tract run from and what is its function?
Vestibular nucleus to the spinal cord
Solitary nucleus to the spinal cord
It relays gravitational sensory information from CN VIII and co-ordinates postural responses such as the balance of the head and neck
It relays gravitational sensory information from CN X and co-ordinates postural responses such as the balance of the head and neck
Where does the tectospinal tract run from and what is its function?
Superior colliculus to the spinal cord
It relays visual information from the visual cortex and retina and orientates the head and eyes
The reticulospinal tract originates from the reticular formation.
The pontine reticulospinal tract modulates voluntary override of the medullary reticulospinal tract.
The pontine reticulospinal tract modulates posture via leg extensors.
The motor cortex is the only brain centre required for co-ordinated movement.
What is the function of the supplementary motor area (SMA)?
Planning and initiation of the final action to be taken
Bimanual coordination
Control of movement sequencing
Control of the distal musculature
What is the function of the pre-motor cortex?
What is the function of the primary motor cortex?
The motor homunculus (the somatotopic arrangement) is evenly distributed for all areas of the body.
The SMA, Pre-motor cortex and Primary motor cortex contribute what percentage of motor fibres to the corticospinal tract?
50%
25%
40%
70%
Corticospinal tract fibres innervate small groups of muscle instead of single muscles and encode the force and direction of movement.
Stroke/tumours may damage UMN, what can this lead to?
Hypertonia
Hypotonia
Hyperreflexia
Hyporeflexia
UMN damage will affect the side of the body contralateral to the damage. This means UMN damage will affect the same side that the damage occurs.
What is the output of the spino-cerebellum pathway?
Reticular nucleus
Red nucleus
Vestibular nucleus
Pre-motor cortex
What is the output of the cerebro-cerebellum pathway?
What is the output of the vestibulo-cerebellum pathway?
What does the spino-cerebellum tract help to control?
Axial musculature and posture
Sends compensatory signals to the primary motor cortex
Control over posture, balance and eye movement.
What does the cerebro-cerebellum tract help to control?
What does the vestibulo-cerebellum tract help to control?
Damage to the spino-cerebellum pathway could lead to what?
Hypotonia, Ataxia, Dysmetria
Asynergy, Ataxia, Dysarthia
Slow saccade impairment, nystagmus
Damage to the cerebro-cerebellum pathway could lead to what?
Slow saccades, nystagmus
Damage to the vestibulo-cerebellum pathway could lead to what?
The vestibulo-ocular reflex is performed by the vestibulo-cerebellum pathway and samples visual disparities. It then provides a correction signal to do what?
Keep an observed image on the retina as the head moves via oculomotor muscles
Make sure the oculomotor muscles contract to a proper extent
Turn the eyes in the same direction as head movement
The function of the cerebellum overall is to act as...?
A sampler - compare inputs and make necessary changes
A timer - coordinating smooth movements
A predictor - executing movements from learnt behaviour
To modulate posture
Name 1. on the cortico-basalgangliga-cortical loop.
Stratium
Globus Pallidus external
Sub thalamic nucleus
Cortex
Name 2. on the cortico-basalgangliga-cortical loop.
Name 3. on the cortico-basalgangliga-cortical loop.
Name 4. on the cortico-basalgangliga-cortical loop.
Striatum
Name the hypokinetic disorder
Parkinsons
Huntingtons
Name the hyperkinetic disorder
In parkinsons, the death of SNc dopaminergic neurons has what effect on cortex feedback?
Decreased stimulation of the striatium leads to less inhibitory drive and therefore higher excitatory drive from the sub-thalamic nucleus, leading to excessive stimulation of an inhibitory signal to the thalamus and thus excitatory signals back to the cortex are reduced. (hypokineticism)
Decreased stimulation of the striatium leads to less inhibitory drive and therefore higher excitatory drive from the sub-thalamic nucleus, leading to excessive stimulation of an inhibitory signal to the thalamus and thus excitatory signals back to the cortex are increased. (hyperkineticism)
In huntingtons, the lack of an inhibitory striatum signal to the GPe leads to what?
Lack of an inhibitory signal to the GPe means that the GPe sends out excess inhibitory signals to the STN. The STN is therefore inhibited and sends out fewer excitatory signals to the SNr/GPi. This in turn causes fewer inhibitory signals to the thalamus and therefore excitatory signals from the thalamus to the cortex increase.
Lack of an excitatory signal to the GPe means that the GPe sends out excess inhibitory signals to the STN. The STN is therefore inhibited and sends out fewer excitatory signals to the SNr/GPi. This in turn causes fewer inhibitory signals to the thalamus and therefore excitatory signals from the thalamus to the cortex increase.
What are the symptoms of parkinsons?
Tremor
Akinesia
Bradykinesia
Excessive movement
Rapid motor patterns
What are the symptoms of huntingtons?
What is ataxia and is it usually associated with basal ganglia or cerebellar dysfunction?
Basal ganglia
Cerebellar dysfunction
Slow movement
Lack of voluntary coordination of muscle movements
Basal ganglia disorders such as Parkinson's have symptoms such as an intention tremor.
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