Motor system FINAL Flashcards
Motor control organisation
2 types
1) Functional segregation
2) Hierarchial organisation
1) Functional segregation: Organised in no of different areas that control different aspects of mvmt
2) Hierarchial organisation:
High order areas of hierarchy involved in more complex tasks (programme, coordinate)
Lower level areas- perform lower level tasks (Execution of mvmt)
Function of brain stem in motor organisation
Passes commands from cortex to spinal cord
Function of motor cortex in motor organisation
Receives info from other cortical areas and sends commands to brainstem and thalamus
Which organs adjusts commands received from other parts of motor control
Function of basal ganglia and cerebellum in motor organisation
Location of motor cortex
Function
Precentral gyrus, anterior to central sulcus
Control fine, discrete, precise VOLUNTARY mvmt
Penfield motor hommunculus: where are legs and head
Legs at midline Head lateral
Which artery supplies the medial part of brain
Lateral corticospinal tract:
Legs at midline (this part of brain in supplied by anterior cerebellar artery– stroke in this area=difficulty walking)
1) Betz cell project from primary motor cortex through internal capsule of basal ganglia
2) Pass through midbrain at cerebral peduncle
3) Through pons
4) Into pyramids of medulla, followed by decussation
5) Descend into lateral corticospinal tract
6) At appropriate level project to ventral horn of spinal cord
7) Synapse with alpha motor neuron which leaves through ventral root, out through spinal nerves to musculature
Anterior corticospinal tract
what muscles
CN nuclei located where
Decussate at level of spinal cord
–> largely input to muscles of thorax, axial musculature
in brainstem
Corticobulbar pathway
1) Head region of motor cortex (think of homonculus-lateral) fibres pass through internal capsule of basal ganglia
2) Synapse in brainstem at CN nucleus
3) CN nerve pass out
Premotor cortex located at
Function
Frontal lobe anterior to M1 (Primary motor cortex)
Planning of movement
Regulates externally cued mvments
-Requires awareness of intrapersonal space and extrapersonal space
Supplementary motor area
function
Frontal lobe, anterior to primary motor medially– closer to midline
- Planning complex movements and programming sequences of mvmts
- Regulates internally driven movements
Association cortex
Which areas
Not strictly motor areas,
Why is the association cortex not regarded as a motor area
Which areas
their activity doesn’t correlate with motor output
> Posterior parietal cortex: ensures movements are TARGETED ACCURATELY to objects in external space
Prefrontal cortex: Involved in SELECTION OF APPROPRIATE movements for a particular course of action
Lower motor neurons refers to those in
Upper motor neurons refers to those in
Spinal cord and brainstem
corticospinal, corticolobular
Pyramidal
Lateral cortcospinal tract
Extra-pyramidal
Basal ganglia + Cerebellum – Adjust commands received from other parts of motor control
Upper motor neuron lesions effects
Negative signs: LOSS OF FUNCTION
- Paresis:Graded weakness of movements
- Paralysis: Plegia
Postive signs: INCREASED ABNORMAL MOTOR FUNCTION
-Spasticity: increased muscle tone
-Hyper-reflexia: Exaggerated reflexes
-Clonus: Abnormal oscillatroy muscle contraction
:Babinski sign
Apraxia
Lesions where result in this? what might these be caused by?
Disorder of skilled movements, not paretic but lost information how to perform
Lesions–STROKE+DEMENTIA of inferior parietal lobe, frontal (Premotor cortex, supplementary area)
Lower motor neuron lesion effects
Weakness Muscle wasting Tongue fasciculations and wasting Nasal speech Dysphagia
Motor neuron disease is what?
Example
Progressive neurodegenerative disease of the motor system
ALS
Structures of basal ganglia include
Caudate nucleus
Lentiform nucleus (putamen + external globus pallidus)
Subthalamic nucleus
Substantia nigra
Ventral pallidum, claustrum, nucleus accumbens, nucleus basalis of Meynert
Basal ganglia function
Elaborating associated movements (e.g. swinging arms when walking; changing facial expression to match emotions)
Moderating and coordinating movement (suppressing unwanted movements)
Performing movements in order
Symptoms of Parkinsons
Cognitive decline
Bradykinesia
Hypomimic face
expressionless, mask-like (absence of movements that normally animate the face)
Akinesia
difficulty in the initiation of movements because cannot initiate movements internally
Rigidity
muscle tone increase, causing resistance to externally imposed joint movements
Tremor at rest
4-7 Hz, starts in one hand (“pill-rolling tremor”); with time spreads to other parts of the body so bilateral
Neuropathology of parkinsons
neurodegeneration of the dopaminergic neurons that originate in the substantia nigra and project to the striatum
