Control of movement Flashcards
What regions of the brain give information to the primary motor cortex in order to allow effective movement?
Prefrontal cortex
Premotor cortex
Supplementary motor cortex
What is the function of the prefrontal cortex in movement?
Planning of movement
Specifies goal of movement.
What is the function of the premotor cortex in movement?
Organises the sequence of movements
What is the function of the supplementary mortor cortex in movement?
Coordination of complex learned responses such as throwing or typing
Coordination of large muscles for typing
What is the function of the primary motor cortex in movement?
Intention produce outcomes,
Produce output to the spinal cord to cause the motor outcome.
What are the pyrimidal tracts?
Pass through the pyrimid of the medullar
Includes the corticospinal tract and the corticobular tract
Give an overview of the corticobular tract.
Corticobular tract originates in the primary motor cortex
innervates the cranial nerves, hence effects the head, neck and face
Axons for each cranial nerve pass through the brainstem until in level with the desired cranial nerve, where they synapse bilaterally with the target nerve
Tract is bilateral so is mirrored on the opposite side of thebody
Ends in the meduallary region
Before synapse is the UMN below synpase is the LMN
Give an overview of the corticospinal tract.
Originates in the primary motor cortex, descending white matter tract.
Innervates the limbs and trunk
Passess through the brain stem to te medulla, 80% of fibres cross the midline to the contralateral side, continue onwards to target
Fibres on the lateral side are called the lateral corticospinal tract, and fibres that continue on are called the anterior corticospinal tract.
Synpases with lower motor neurons in the ventral grey horn.
Note their are multiple upper and lower motor neurons in one spinal tract.
Is a bilateral structure
What are the signs of an upper motor neuron lesions?
Weakness
No atrophy
no fasiculations
increases reflexes
increased tone
What are the signs of a lower motor neurone lesion?
Weakness
Atrophy
Fasiculations
decreased reflexes
decreased tone
What is ankle clonus?
Involuntary and rhythmic muscle contractions caused by a permanent lower motor lesion
often seen when the foot is relaxed, rotate the ankle then suddenly dorsiflex, foot will repeatedly give small twtiching dorsiflexions, if more than twice this is a sign of clonus.
What does hemiplegic meaning?
Affecting one side of the body
often muscle weakness, wasting or flexion.
What does quadriplegia mean?
Affecting all limbs and trunks
What does paraplegia mean?
Paralysis of the lower legs and body, often due to spinal cord injury.
What are the different lobes of the cerebellum?
The anterior lobe
The posterior lobe
The flocculonodular lobe.
What is the purpose of the cerebellum?
Coordination
Maintains balance and posture
Tone of muscles
Motor learning
Maps original to intended position
All subconscious
*Note does not intiiate movement, uses sensory information and other inputs to fine tune motor activity.
What movement are indiactors of movement disorders caused by the cerebellum?
Impairment is ipsilateral to the lesion
Most apparent on movement not rest
No numbness or paralysis
Ataxia - coordination, balance and speech, affects force range and direction of movement
Past pointing - finger touch test
Intention tremor
Dysdiadochokinesis - difficulty with repetitive supination/pronation
Scanning speech - break or pause between sylables, not change in tone
What are the key features of an intention tremor in cerebellum damage?
Tremor starts small and becomes more noticeable just before action is complete
Tremor stops when the action is completed.
Give an overview of the structure of the cerebellum?
Inferior to the occipital and temporal lobes, seperated from them by the tentorium cerebelli.
Located within the posterior cranial fossa
Same level but posterior to the pons
Contains white and grey mater, white matter has deep nuclei.
What is dysmetria?
Inability to control the distance, speed and range of motion required for a co-ordinated task.
What are the key clinical signs to indicate a problem with the cerebellum?
Intention tremor
Loss of balance when walking heal to toe
What are the key clinical signs of a problem with the dorsal column?
Fall when eyes are shut
What is cerebellar gait ataxia?
Poor muscle control that causes clumsy voluntary movements, often appear drunk when they walk.
What three different loops summarise the roles of the basal ganglia?
The motor loop - plan movement, selecting and inhibiting specific motor activty to create a purposeful and co-ordinated movement without unneeded activity.
Cogintive/association loop - muscle memory, learning patterns, training brain to favour a certain pattern of movement, reward feeling when successfully complete a task.
limbic circuit - links to emotion centre, motor expression of emotion, hunched when sad etc.
What is the main difference between the direct and indirect basal ganglia pathway?
The direct pathway initiates movement
The indirect pathwat inhibits movement
Both circulate symptoms to and from the cortex.
What is the indirect basal ganglia pathway?
What is the direct basal ganglia pathway?
What are the hyperkinetic signs of a basal ganglia disorder?
Hyperkinetic - increased contraction
Athetosis - involuntary writing movements, slow writing with hands and fingers
Chorea - fidgety distal limbs, patients often hide this by sitting on their hands, looks like very expressive when talking
Hemiballismus - sudden flinging
Resting tremor - rhymtic oscillating movement
What are the hypokinetic signs of a basal ganglia disorder?
Bradykinesia/slowness
Rigid increase in muscle tone
What is the common symptoms seen in a Parkinsons case?
Bradykinesia
Rigidity
Tremor - pill rolling tremor, at rest
Postural instability
What region of the brain if often associated with Parkinsons disease?
Diminished substantia niagra, decreased levels of dopamine, appears less black.
What are the different classifications of parkinsons like diseases?
Parkinsonism - disorders that produces basal ganglia disfunction
Parkinsons disease or idiopathic parkinsonism - most common form, from damage to substantia niagra
Secondary parkinsonism - results from identifiable causes such as a virus, toxin, drug or tumour, type of parkinsonism
Parkinsonism plus syndromes - symptoms mimic parkinsonis but is caused by some other neurological disorder.
What is often the history of a parkinsons patient?
Gradual onset
Tremor at rest, first noticed in hands
Stiffness and slowness of movement
Difficulty initiating movements
Falls - not frequent early on
Hand writing that gets smaller as goes on
What are signs in the gait that a person has parkinsons disease?
Hunced
Small shuffling steps
Slow
Marche a petit pieds - abnormally small steps when stood up straight
Reduced arm swing
What is punch drunk syndrome?
Repeated damage to the brain from head bangs (football , rugby, boxing etc)
result in neurological damage
Symptoms similar to dementia, behvaioural and mood changes, problems with movement, planning is difficult, easily get lost.
What is the face of a person with parkinsons often like?
An expressionless face
Often mask like with reduce blinking
Movements are rigid or slow to response
How does a person who has suffered from a stroke often walk?
Why?
Elbows and hands flexed
Swinging legs
- upper limb flexors are stronger than extensors
-lower limb extensors are stronger than flexors
What clues in an examination might indicate Parkinson disease?
Monotonous or slurred speech
tremor
Increased tone or cogwheeling
Normal power, reflexes, sensation and co-ordination
Co-ordination might be slow
Patient is unable to draw a smooth spiral
Unable to open and close hands quickly and easily
What is levodopa induced dyskinesias?
Prolonged treatment with levodopa or too high doses, results in involuntary rapid swinging movements or too much movement in parkinsons patients
Patients often prefer this to be unable to move.
Shows the importance of tailoring treatment.
What is the functional difference between the lateral and anterior corticospinal tract?
Lateral corticospinal tract typically provides motor innervation to the peripheral or extermities muscles
Anterior corticospinal tract typically supplies the trunk or axial muscles with motor innervations
Give a description of the mechanism of the lateral corticospinal tract.
Originates in the primary motor cortex of the brain.
Primary neuron’s axon travels through the internal capsule in the cerebrum, then travels through the crus cerebri in the mid brain and down the pyramids of the medulla.
Finally travels through the contralateral lateral corticospinal tract region of white matter.
At the correct vertebral level the axon will enter the ventral horn and synpase with a secondary neurone which leaves by the ventral root and travels to innervate the intended muscle.
Give a description of the journey of the anterior corticospinal tract.
Originates in the primary motor cortex of the brain.
Primary neuron’s axon travels through the internal capsule in the cerebrum, then travels through the crus cerebri in the mid brain and down the pyramids of the medulla.
Continues on the ipsilateral side down the anterior corticospinal tract white matter region
At the correct vertebral level the axon enters the ventral horn on the contralateral side of the spinal cord and synapses with a secondary neurone which then carries information to the desired muscle
Describe the pathway of the corticobulbar tract.
Primary neurons originate in the primary motor cortex and travel through the internal capsule.
Synapses at the cranial nerve nuclei for cranial nerves that require motor innervation (CN3 -7, then 9-12), mostly located in the brainstem.
Note the primary motor neurones and nuclei are bilateral structures, and most neurons synapse bilaterally.
What cranial nerve nuclei have unique synapse patterns with the corticobulbar tract?
The facial nuclei (CN7) is divided into upper and lower nuclei, the primary neurone fuses bilaterally with the upper nuclei and contralaterally with the lower nuclei , this mirrors the sections of the face.
The nucleus ambiguus, innervates the CN1X, X and XI bilateral.
Hypoglossal CN12 is contralateral only.
Indicate how you can tell the difference between an upper and a lower motor neuron lesion in the facial cranial nerve.
This is an important clinical distinction between Bells Palsy and stroke
An upper motor neuron lesion loses ability to move lower face but maintain movement in the upper face (still able to move eyebrows up)
A lower motor neuron loses ability to move upper and lower face.
What is the function of CN1 Olfactory?
Sense of smell
What is the function of CN2 Optic?
Vision
What is the function of CN3 Oculomotor?
Motor innervation to all eye rectus muscles, NOT the superior oblique and the lateral rectus
What is the function of CN4 Trochlear?
Motor innervation to the superior oblique muscle in the eye, move the eye down and in
What is the function of CN5 trigeminal?
Sensory to face and muscles of masication,
Minor roles in hearing, swallowing and soft palate function
What is the function of CN6 abducens?
Motor to the lateral rectus muscle of the eye
What is the function of CN7 facial?
Provides motor to the facial expression, parasympathetic supply to salivation and lacrimation, some taste to the tongue and sensation of the ear
What is the function of CN8 vestibulocochlear?
Aids balance and hearing
What is the function of CN9 glassopharangeal?
Taste
Some sensory to the tongue and ear, parasympathetic salivation, visceral sensation to the carotid body.
What is the function of CN10 vagus?
Motor to pharangeal muscles, uvula at the back of the soft palate.
parasympathetic to some abdominal and thoracic organs.
Some sensation from the ear
What is the function of CN11 spinal accessory?
Motor to sternoclasdomastoid and the trapezius (shoulder shrugging muscles and head rotation)
What is the function of CN12 hypoglossal?
Motor to the tongue.
