Motor Pathways Flashcards
What is functional segregation of motor control
Motor system organised in a number of different areas that control different aspects of movement
What is hierarchical organisation of motor control
High order areas of hierarchy are involved in more complex tasks (programme and decide on movements, coordinate muscle activity)
Lower level areas of hierarchy perform lower level tasks (execution of movement)
What modulates and adjusts commands from the motor cortex
Basal ganglia and cerebellum
Describe position of the primary motor cortex
Precentral gyrus, anterior to the central sulcus
Function of the primary motor cortex
Control fine, discrete, precise voluntary movement
Provides descending signals to execute movement
Type of organisation of the primary motor cortex?
Somatotopic
What’re the 2 descending motor pathways
LATERAL and ANTERIOR CORTICOSPINAL PATHWAYS
Describe the lateral corticospinal pathway starting from the primary motor motor cortex
Primary motor cortex motor neurones send their axons down through subcortical structures known as the internal capsule
Internal capsule becomes the cerebral penduncle
fibres pass through the pons and then reemerges at the pyramids in the medulla where 90-95% of fibres decussate.
the fibres then descend along the lateral corticospinal tract.
- At the appropriate level, the fibres synapse with alpha motor neurones in the ventral horn of the spinal cord
axons of those neurones go out through the ventral root to the spinal nerve and out to the muscle intended
Internal capsule becomes the XX
cerebral penduncle
Describe the anterior corticospinal pathway starting from the primary motor motor cortex
Primary motor cortex motor neurones send their axons down through subcortical structures known as the internal capsule
Internal capsule becomes the cerebral penduncle
fibres pass through the pons and then reemerges at the pyramids in the medulla
5-10% of fibres here DO NOT decussate and descend to form the anterior corticospinal tract
at the appropriate level the fibres then cross over (decussation is actually IN the spinal cord)- these fibres supply the axial musculature
Anterior corticospinal tract supplies the X muscles
axial muscles
What are the CORTICOBULBAR PATHWAYS, example?
The primary motor cortex’s projections to the motor nuclei within the brainstem e.g. hypoglossal nucleus
PREMOTOR CORTEX location?
Frontal lobe anterior to the primary motor on the lateral side of the head
PREMOTOR CORTEX function? Example of its action?
Planning of movements
Regulates externally cued movements
intra- and extra-personal space consideration
Resaching for an apple
SUPPLEMENTARY MOTOR AREA/CORTEX location?
Anterior to M1, medial to the premotor cortex (dorsal side of head)
SUPPLEMENTARY MOTOR AREA/CORTEX function?Example of its action?
Planning complex movements; programming sequencing of movements
Regulates internally driven movements
e.g. the mechanics of speech
SMA becomes active when thinking about a movement before executing that movement
the 2 ASSOCIATION CORTICES?
- POSTERIOR PARIETAL CORTEX
- PREFRONTAL CORTEX
POSTERIOR PARIETAL CORTEX location?
Behind the somatosensory cortex
PREFRONTAL CORTEX location?
Anterior side of brain
PREFRONTAL CORTEX location?
Involved in selection of appropriate movements for a particular course of action
POSTERIOR PARIETAL CORTEX function?
Ensures movements are targeted accurately to objects in external space
Which brain area has this function:
Ensures movements are targeted accurately to objects in external space
Ensures movements are targeted accurately to objects in external space
Which brain area has this function:
Involved in selection of appropriate movements for a particular course of action
Involved in selection of appropriate movements for a particular course of action
Which brain area has this function:
Planning complex movements; programming sequencing of movements
Regulates internally driven movements
SUPPLEMENTARY MOTOR AREA/CORTEX
Which brain area has this function:
Regulates externally cued movements
PREMOTOR CORTEX:
Which brain area has this function:
Control fine, discrete, precise voluntary movement
Provides descending signals to execute movement
Primary motor cortex
Which brain area has this function:
The primary motor cortex’s projections to the motor nuclei within the brainstem
Corticobulbar pathway
What/where is the:
LOWER MOTOR NEURON (3 places)
The α-motor neuron in the spinal cord, in the ventral horn- and its process out to the musculature (also in the brainstem e.g. the axon from the hypoglossal nucleus)
What is:
UPPER MOTOR NEURON
The motor neuron in the primary motor cortex- they have corticospinal or corticobulbur fibres projecting to the next neuron
What is:
PYRAMIDAL tract
Lateral corticospinal tract, main motor tract
what does the EXTRAPYRAMIDAL tract innervate
Basal ganglia and cerebellum
What is:
Paresis
Graded weakness of movements
What is:
Paralysis (plegia
Complete loss of muscle activity
What is:
Spasticity
Increased muscle tone
What is:
Hyper-reflexia
Exaggerated reflexes