Motor Control Flashcards
What are the two types of major descending tracts?
-Pyramidal tracts
-Extra pyramidal tracts
What do the pyramidal tracts pass through?
The pyramids of the medulla
What are the two main pyramidal tracts.
-Corticospinal
-Corticobulbar
What are the pyramidal tracts involved in.
Voluntary movements of the body and face.
What are the 4 main extra pyramidal tracts.
-Vestibulospinal
-Tectospinal
-Reticulospinal
-Rubrospinal
What are the extra pyramidal tracts involved in.
involuntary (automatic) movements for balance, posture and locomotion
Which tracts do not pass through the pyramids of the medulla.
Extra pyramidal tracts:
-Vestibulospinal
-Tectospinal
-Reticulospinal
-Rubrospinal
What is the vestibulospinal tracts involved in.
To maintain head and eye coordination, upright posture and balance.
What is the tectospinal tracts involved in. + origin
From superior colliculus of midbrain.
Orientation of the head and neck during eye movements
What is the reticulospinal tracts involved in and where does it originate from?
- Most primitive descending tract- from medulla and pons
- Changes in muscle tone associated with voluntary movements
- postural stability
What is the rubrospinal tracts involved in and where does it originate from?
- From red nucleus of midbrain
- In humans mainly taken over by corticospinal tract
- Innervate lower motor neurones of flexors of upper limb
Where is the primary motor cortex located.
In the precentral gyrus, anterior to the central sulcus.
Where is the premotor area located.
Anterior to the primary motor cortex.
Where is the supplementary motor area located.
Located anterior and medial to primary motor cortex.
Where does the corticospinal tract decussate.
In the medulla.
What muscle groups does the lateral corticospinal tract innervate.
Limb muscles
What muscles groups does the anterior corticospinal tract innervate.
Trunk muscles.
What are three negative signs of an upper motor neuron lesion.
-Loss of voluntary motor function
-Paresis: graded weakness of movements
-Paralysis (plegia): complete loss of voluntary muscle activity
What are three positive signs of an upper motor neuron lesion.
-Increased abnormal motor function due to loss of inhibitory descending inputs
-Spasticity: increased muscle tone
-Hyper-reflexia: exaggerated reflexes
-Clonus: abnormal oscillatory muscle contraction
-Babinski’s sign
how is apraxia best described?
A disorder of skilled movement.
What are the two most common causes of apraxia.
STROKE & DEMENTIA
Symptoms of a lower motor neuron lesion.
-Weakness
-Hypotonia (reduced muscle tone)
-Hyporeflexia (reduced reflexes)
-Muscle atrophy
-Fasciculations: damaged motor units produce spontaneous action potentials, resulting in a visible twitch
-Fibrillations: spontaneous twitching of individual muscle fibres; recorded during needle electromyography examination
Motor neuron disease is best described as.
A progressive neurodegenerative disorder of the motor system.
What is motor neuron disease also known as?
Amyotrophic Lateral Sclerosis (ALS)
What is Babinski’s sign
Reversed plantar reflex, (extension of toes rather than curling downwards after sole of foot is stimulated).
What is Babinski’s sign indicative of.
Upper motor neuron disease/ lesion.
What is parkinsons?
Degeneration of the dopaminergic neurones that originate in the substantia nigra and project to the striatum
What are the symptoms of parkinsons?
- Bradykinesia- Slowness of small movements (doing up buttons, handling a knife)
- Akinesia- Difficulty in initiation of movements because can’t initiate movements internally
- Hypomimic face- Expressionless, mask-like (absence of movements that normally animate the face)
- Rigidity- Muscle tone increase, causing resistance to externally imposed joint movements
- Pill rolling tremor
What is huntington’s
Degeneration of inhibitory GABAergic neurones in the striatum → caudate and then putamen
Describe the aetiology, (inheritance pattern) of huntingtons
It’s genetic- autosomal dominant, chromosome 4 has a CAG repeat
What are the symptoms of huntington’s
- Choreic movements (chorea is dance)- rapid jerky involuntary movements of body
- Hands and face affected first
- Then legs
- Then rest of body
- Speech impairment
- Dysphagia
- Unsteady gait
- Later stages has cognitive decline and dementia
What is ballism?
- usually from stroke affecting subthalamic nucleus
- generally one sided and causes uncontrolled flinging of extremities
- Symptoms occur contralaterally
What does the vestibulocerebellum do? And what does a lesion in this area do?
- Regulation of gait, posture and equilibrium
- Coordination of head movements with eye movements.
Damage (tumour) causes syndrome similar to vestibular disease leading to gait ataxia (unsteady, staggering gait) and tendency to fall (even when patient sitting and eyes open)
What does the spinocerebellum do? (3)
- Coordination of speech
- Coordination of limb movements
- Adjustment of muscle tone
What does damage to the spinocerebellum do?
Damage (degeneration and atrophy associated with chronic alcoholism) affects mainly legs, causes abnormal gait and stance (wide-based)
What does the cerebrocerebellum do? (5)
- Coordination of skilled movements
- Cognitive function
- Attention
- Processing of language
- Emotional control
What does damage to this section do? (Cerebrocerebellum)
Damage affects mainly arms/skilled coordinated movements (tremor) and speech
A person experiencing these symptoms most likely has what?
-Ataxia
-Dysmetria
-Intention tremor
-Dysdiadochokinesia
-Scanning speech
cerebellar dysfunction
What do alpha motor neurones do?
They are the lower motor neurones of the brainstem and spinal cord
They innervate the extrafusal muscle fibres of the skeletal muscle and their activation causes muscle contraction
What is the motor neuron pool?
Contains all alpha motor neurones innervating a single muscle
Where are alpha motor neurones located?
In the anterior horn of grey matter of spinal cord
also located in the brainstem
What is the Jendrassik manouevre?
If you clench your teeth, make a fist or pull against locked fingers when your patellar tendon is tapped, the reflex becomes larger
What is hyperflexia associated with?
UMN lesion, loss of descending inhibition
What is clonus?
- A sign of UMN dysfunction
- Involuntary and rhythmic muscle contractions
- Loss of descending inhibition
What is hypoflexia associated with
LMN diseases
What is the most common muscle type change after training?
Type IIB (Fast fatigue able) to type IIA (Fast fatigue resistant)
When is type I to type II muscle fibre change common?
After severe deconditioning or spinal cord injury.
What kind of muscle fiber changes is associated with aging?
loss of type I and II fibres but also preferential loss of type II fibres.
What are the two mechanisms by which the brain regulates the amount of force a single muscle can produce?
-Recruitment
-Rate coding
What is the factor called that prevents neuronal death and promotes growth of neurons after injury?
Neurotrophic factors
What are fasiculations and what kind of motor neurone disease do you get them in?
Tiny muscle twitches, you get them in lower motor neurone disease
