Motor systems and controls Flashcards
What is motor control?
the ability to make dynamic postural adjustments and direct body and limb movement in purposeful activity
What components are necessary for motor control?
- Normal muscle tone
- Normal postural tone and postural mechanisms
- Selective movement
- Co-ordination
What affects motor control?
Neurological insults (stroke, TBI, Parkinsons, MS)
What are the 3 functions of the motor system?
- Controls a complex neuromuscular network
- Sends movement commands to muscles and joints that must be stabilised.
- Movement whether voluntary or involuntary or reflexive is achieved by contraction of skeletal muscles
What makes up the Motor System?
- Cortical and subcortical areas of grey matter
- Grey matter of the spinal cord
- Cerebellum and Basal Ganglia
- Direct pathways nerve tracts
- Indirect pathways nerve tracts
- Efferent nerves
What are the properties of neurons?
Excitation - generate impulses in response to stimulation and conduction of impulses between neurons.
What are the properties of neural networks?
Processing of activity directed to a particular end and relay of output of processing to other centres in the nervous system.
What are the 3 neurones?
- Motor neurons
- Sensory neurons
- Interneurons
Are motor neurons efferent or afferent?
efferent (send message away)
Are sensory neurons efferent or afferent?
afferent (send message towards)
What are interneurons?
Neurons that transmit impulses between other neurons
What are the 3 levels of hierarchy of motor control?
- Cerebral cortex
- Brain stem
- Spinal cord
What is the function of the cerebral cortex?
Externally guided movements eg. picking up objects, using tools, moving eyes to explore faces, making gestures
What are the 3 major areas of the frontal lobe?
- Primary motor cortex - major control region for initiation of voluntary movements
- Premotor cortex
- Supplementary motor cortex
What does the brain stem consist of?
- Midbrain
- Pons
- Medulla Oblongata
What is the function of the brain stem?
- Axons project and regulate the segmental networks of the spinal cord
- Controls posture and stabilisation of muscles during movement
- Integrates visual and vestibular information with somatosensory input to modify movements initiated by the cortex.
What is the function of the spinal cord?
neurons mediate automatic reflexes eg. stretching
What is the function of the cerebellum?
Projects to both brainstem and thalamus and improves accuracy of movement
What is the function of the basal ganglia?
Receives inputs from all cortical areas. Projects to thalamus and then to areas of the cortex involved in motor planning
What can result from damage to the basal ganglia?
Too much activation = twitches and movement bursts eg. Huntington’s Chorea
Too little force = rigidity eg. parkinsons disease
What does hyperkinetic mean?
Too much activation
What does hypokinetic mean?
Too little force
Does the spinal cord contain interneurons?
Yes
What is the white matter tract?
Located in spinal cord, provides a path for nerve impulse propagation
What is the grey matter tract?
Located in the spinal cord, Receives and integrates all of the outgoing information.
How many pairs of spinal nerves are there?
31
Is the spinal cord part of the PNS or CNS?
PNS, it connects the CNS to receptors, muscles and glands
What are the 2 points of attachment to the cord?
Posterior root and Anterior root
Describe the posterior root?
Contains sensory nerve fibers and conducts nerve impulses from the periphery into the spinal cord.
Describe the anterior root?
Contains motor neuron axons and conducts impulses from the spinal cord to the periphery
What are the 3 different systems spinal nerves are distributed in?
- Branches
- Plexuses
- Intercostal nerves
What is a complete spinal injury?
Total loss of movement or sensation - permanent paralysis
What is an incomplete spinal injury
Incomplete injury can result in movement and sensation abnormalities
What is paraplegia?
Retain use of hand, arms and shoulders, damage to spinal cord located in thoracic, lumbar or sacral regions
What is quadriplegia?
Limited use of hands, arms and shoulders, damage to the cervical region
Which age group has the highest number of SCI?
15-24 years, predominantly male
Which SCI is the most common?
Quadriplegia (incomplete)
What is the primary cause of SCI in Australia?
Traffic accidents
What are the 2 motor descending pathways?
Direct (Cortex of brain to skeletal muscles) and indirect (synapses, basal ganglia, thalamus, reticular formation and cerebellum)
What is a direct motor pathway?
Upper motor neuron system facilitates or inhibits the lower motor neuron system
What parts of the body are controlled by direct pathways?
The face, vocal cords, hands and feet
What are the potential movement impairments caused by damage to the upper motor neuron system?
Upper and/or lower limb paralysis or impairment, spasticity, impaired balance and impaired co-ordination
Name 3 upper motor neuron conditions?
- Stroke
- TBI
- Brain tumours
- Cerebral palsy
- MS
What are lower motor neurons?
Spinal cord and the motor nuclei in the cranial nerves located in the brain stem
What are lower motor neuron systems responsible for?
Posture and movement
What are the potential movement impairments caused by damage to the lower motor neuron system?
partial damage - weakness/paresis of muscles
Complete severing - paralysis, hypotonicity/flaccidity of muscles and absence of spinal reflexes
Name 2 lower motor neuron system conditions?
- Lesions eg. tumours of spinal cord
- Poliomyelitis
- MND
- Guillian Barre
What are the 3 indirect (extrapyramidal) nerve pathway tracts?
- Synapses in the basal ganglia, thalamus, reticular formation and cerebellum.
- All descending motor tracts other than the corticospinal and corticobulbar tracts
- The motor cortex, nuclei in the brain stem
