UMNs and Control of Movement Flashcards
What is the function of a simple spinal central pattern generator?
Can command rhythmic, alternating activity that moves a limb
What is the essential features of a simple spinal central pattern generator?
Excitatory interneuron displays oscillatory (pacemaker) activity
How many levels are involved in the motor control hierarchy?
At least three levels
How are controlled movements initiated and influenced?
By multiple sensory inputs and a need to move using internal mechanisms
What is the motor control hierarchy at its simplest?
High = neocortical association areas and basal ganglia Middle = motor cortex and cerebellum Low = brainstem and spinal cord
Where do the descending spinal tracts arise from?
Cerebral cortex and brainstem
What are the descending spinal tracts involved in?
Control of movement, muscle tone, spinal reflexes, spinal autonomic functions and modulation of sensory transmission to higher centres
What are the two important divisions of the descending spinal tract?
Lateral and ventromedial
What is the lateral pathway of the descending spinal tract involved in?
Voluntary control of distal musculature = under control from cerebral cortex
What is the ventromedial pathway of the descending spinal tract involved in?
Control of posture and locomotion = under control of brainstem
What is the major lateral pathway of the descending spinal tract?
Corticospinal tract = longest and one of largest CNS tract
Where are the cell bodies of the corticospinal tract located?
Motor cortex (BA4 and BA6) and somatosensory areas of the parietal cortex
Where do the axons of the corticospinal tract flow?
To the base of the medulla forming a tract (the medullary pyramid)
Where do most fibres of the corticospinal tract cross?
At the pyramidal decussation = forms the lateral corticospinal tract
What happens to fibres of the corticospinal tract that don’t cross at the pyramidal decussation?
Stay ipsilateral to form the ventral corticospinal tract and decussate more caudally