Subcortical And Cortical Control Of Movement Flashcards
What three parts make up the brainstem?
• Medulla
• Pons
• Midbrain
What are the two important brainstem nuclei group?
• Reticular formation
• Vestibular nuclei
What is the function of the vestibulospinal tract?
It provides the sense of balance and spatial orientation for the purpose of coordinating movement with balance
What is the function of the reticulospinal tract?
Maintaining tone, balance and posture (internal)
Give an example of the reticulospinal tract in action
The calf muscles contracting to stabilise the body before the voluntary action of pulling against the wall with the biceps
What are the three parts of the cerebellum?
• Superior cerebellar peduncle
• Middle cerebellar peduncle
• Inferior cerebellar peduncle
What is the function of the superior cerebellar peduncle?
It’s an efferent (out) pathway to the red nucleus, the cortex (via the thalamus) and the superior colliculus
What is the function of the inferior cerebellar peduncle?
It carries information to and from the spinal cord (and the body) and vestibular nuclei
What is the red nucleus and why is it called that?
• A roughly spherical collection of cell bodies in the midbrain
• Called red because it’s extremely vascular - in fresh tissue it is distinctly pinker than the surrounding tissue
Where does the red nucleus receive its input from?
Cerebellum and primary motor cortex
What part of the spinal cord are the rubrospinal fibres in?
Ventrolateral part
Where do the rubrospinal fibres terminate?
Primarily in the cervical and lumbar enlargements of the spinal cord
What are the two pathways through the basal ganglia?
• Direct
• Indirect
What is the function of the direct loop through the basal ganglia?
• Has an excitatory effect on cortex
• Net effect is pro-movement
What is the function of the indirect loop through the basal ganglia?
• Has an inhibitory effect on cortex
• Net effect is anti-movement
What does damage to the basal ganglia cause?
States where there is too much or too little movement (especially self-generated movements)
What does damage to the cerebellum cause?
States where movements can still be made, but they are uncoordinated
How can you demonstrate somatotropin of the motor cortex with modern equipment?
• Transcranial magnetic stimulation
• Stimulates the motor cortex and produces twitches of movement
What are the four ways the main motor regions of the cerebral cortex can be identified?
• Neurones increase their firing rates before movements and specific features of this activity are often closely related to specific movement features
• Neurones send their axons to terminate in motor centres in the brainstem and spinal cord
• Electrical stimulation in these areas elicits movements
• Neurones send their axons to connect most densely with other motor areas
What is the function of the primary motor cortex?
• Code for basic parameters of movement (i.e. force, direction, extent and speed)
• Fires around 5-100ms before movement onset
• Touch - vibration, heat, pain, pressure
• Proprioception - afferent information, including joint position sense, kinaesthesia and sensation of resistance
What do neurones in the non-primary motor cortex do?
Code for the more complex aspects of movement
What are the three parts of the motor cortex?
• Primary motor cortex
• Pre-motor cortex
• Supplementary motor cortex
What is the function of the pre-motor cortex?
• Planning movement
• Spatial guidance of movement
• Sensory guidance of movement
What is the function of the supplementary motor cortex (SMA)?
• Coordinating temporal sequences of actions
• Bimanual coordination
• Initiation of internally generated (as opposed to stimulus driven) movement
What is the function of the posterior parietal cortex?
• Integration of sensory, visual information to execute complex movement in the environment
• Representations for different motor effectors (e.g. arm vs eye)
• A command apparatus for operation of the limbs, hands and eyes within immediate extrapersonal space
What are the origins of the corticospinal tract?
• Primary motor cortex (30%)
• Premotor and supplementary motor cortex (30%)
• Somatosensory, parietal, cingulate cortex (40%)
How does complexity change as you go up the brain?
Complexity increases
