Motor System Flashcards
Are roles in movement More complex and abstract moving anteriorly or posteriorly through the frontal lobe
Anteriorly
Most important 2 lobes in motor control
Frontal
Posterior parietal
Does each cerebral hemisphere control the ipsilateral or contralateral side of the body
Contralateral
3 levels of motor control
Conceptual level - goal of action
Response level - goal translated to effector system
Motor implementation level - translate movement into pattern of muscular activation
Which brain areas planning movement
Posterior parietal cortex
Frontopolar cortex
Brain areas that organise movement
Supplementary motor area
Premotor cortex
Brain area that executes movement
Primary motor cortex
Which brain area controls intention/desire to move
Posterior parietal cortex
Which brain area controls the decision to move
Frontopolar cortex
Which brain area controls sequences of motion
Supplementary motor area
Which brain area is involved in learning and executing complex movement guided by sensory info
Premotor cortex
Which brain area causes movement of particular body parts
Primary motor cortex
Location and role of Broadmann areas 39-40
Posterior parietal cortex
Form intentions
Use of cognitive control/ executive function
Override automatic thoughts and behaviours
Decision making
Perception
Knowledge
Goals
Change form habitual response
Bias selection of actions and thoughts from all possibilities
Effects of prefrontal cortex lesions
Unilateral - mild defects
Bilateral - dramatic behavioural and personality changes, loss of goal orientated behaviour
Which Brodmann areas plan goal directed behaviour
9 10 46
Effects of lesions in brodmann area 46
Attention
Working memory
Decr Ability to inhibit a motor response to a stimulus
Role of medial prefrontal cortex in movement
Monitor ongoing activity
Modulate degree of cognitive control needed to continue behaviour
Orbitofrontal cortex role in movement
Reward mediated behaviours
Which brodmann area in the orbitofrontal cortex controls reward mediated behaviour
11
Brodmann area 11 lesion effects
Pseudopsychopathic behaviour
Impulsiveness, jugular attitude, puerility, sexual disinhibition, complete lack of concern for others
Which boadmanns areas make up Broca’s area and which hemisphere is it in
44 45
Left hemisphere
Does Broca’s area or wernickes area control production of speech movements
Broca’s
Broca’s area lesion effects
Motor aphasia -
Short/incomplete sentences
Writing difficulty
Substituting words/sounds
Speak sentences that dont make sense
Retain reading and speech understanding
Which brodmann area makes up the frontal eye fields and what is their function
8
Control of visual attention and eye movements
Effect of frontal eye field lesion
Ipsilateral - Eye deviates toward side of lesion
Bilateral - oculomotor apraxia
Oculomotor apraxia
Pt cannot move eyes horizontally or quickly
Pt must turn head when following moving object to compensate for lack of eye movement
Supplementary motor area role in movement
Organises internally guided actions according to preferences and goals
Proactive Control of motor readiness
Reactive inhibition of unwanted movements
Determines response threshold
Plans future elements in movement series
Which part of the brain allows sudden urgent movements/delays, eg running away or unforeseen stops
Supplementary motor area
Premotor cortex role in movement
Organises externally sensory guided actions
Lesion of secondary motor areas effects
Motor Apraxia
Motor apraxia
Difficulty performing complex motor tasks including skilled movements and gestures, desire to perform movement, reflexes and muscle strength uneffected
What is the milder version of motor ataxia
Dyspraxia
Why is only minimal damage caused by unilateral secondary motor area lesions
Contralateral area can take over function
Primary motor cortex function and brodmann area
Execution of movements
4
Which brain area does the corticospinal tract connect to
Primary motor cortex
Axons of Which cells in the Cortex form the corticospinal tract
Pyramidal cells
What is represented by size of a body part on the motor homunculus
Complexity of movement
Lesion of primary motor cortex effects
Paralysis
Hemiplagia
Loss of voluntary movement on the Contralateral side of body
Why are the lower limbs not effected by MCA strokes
Lower limbs motor region supplied by Anterior cerebral artery
Why is an MCA infarction at at proximal M1 segment more dangerous than at the distal M3 segment
M1 effects supply to basal ganglia as well as motor cortex
M3 only effects motor cortex
What do corticospinal and corticobulbar axons from the somatosensory cortex do
Modulate somatosensory input, eg suppress nocioceptive reflexes
Do the basal ganglia and cerebellum impact lower motor neurones directly or indirectly
Indirectly through UMNs in VL thalamus and pri motor cortex
Where does the corticospinal tract decussate
C1-c5
Which tracts make up the pyramidal tracts
Corticospinal and corticobulbar
Do injuries effecting the corticospinal tract cause motor defects on the same or opposite side
Opposite if injury above spinal cord medulla junction
Same if below spinal cord medulla junction
Where does the anterior corticospinal tract terminate and what does it control
Cervical cord
Voluntary movements of neck
What does the lateral corticospinal tract comptroller
Thumb and digit movements
Spinal reflexes
What does the corticobulbar tract control
Eye and face muscles
Where does the corticobulbar tract terminate
Cranial nerve III IV V VI VII nuclei
Pontine nuclei
Reticular formation
Red nucleus
Why do upper motor neurone lesions in the corticobulbar tract cause forehead sparing
Forehead has bilateral innervation
What are the main 3 extrapyramidal tracts
Reticulospinal
Lateral vestibulospinal
Rubrospinal
What does the reticulospinal tract control
Autonomic control of sympathetic pre ganglionic neurons
Drives respirations
General arousal of spinal cord
What does the lateral vestibulospinal tract control
Posture and balance
Antigravity muscles of lower body
What does the rubrospinal tract control
Muscle tone in upper limb flexor muscle groups
Inhibits extensor tone
Where does the rubrospinal tract terminate
Cervical and thoracic spinal cord
2 minor extrapyramidal tracts
Medial vestibulospinal - reflex coordination of head and neck muscles with extra ocular eye muscles
Tectospinal - coordinates voluntary head and eye movement
Spasticity
Abnormally increased muscle tone
Clonus
Series of jerky contractions of a muscle following sudden stretching of the muscle
Hyperreflexia
Abnormally brisk tendon reflex
Is spasticity characteristic of upper or lower motor neurone lesions
Upper
Are tendon reflexes increased or decreased in spasticity
Increased
Does the motor cortex activate or inhibit the extrapyramidal tracts
Inhibit
What does extrapyramidal system hyperactivity cause
Hyperactive stretch reflexes
Spasticity
Decorticate posturing
Addicted and flexed arms
Wrists and fingers flexed on chest
Legs internally rotated and stiffly extended
Plantarflexion
What does decorticate posturing indicate damage to
Corticospinal tract above or in midbrain
Decerebrate posturing
Arms addicted and extended
Wrists pronated and fingers flexed
Legs internally rotated and stiffly extended
Plantarflexion
What does decerebrate rigidity indicate damage to
Brain injury at upper brainstem level
What causes decerebrate and decorticate rigidity
Hyperactive stretch reflexes and spasticity caused by loss of motor cortex inhibition to extrapyramidal system
