Answer
Upper motor neurons may synapse directly with lower motor neurons; alternatively they may synapse with local circuit neurons which then synapse with lower motor neurons.
Cererbro-cortical UMNs are concerned with the execution of voluntary movements. UMNs that originate in brain stem areas have different functions: thy regulate muscle tone, control postural muscles, and maintain balance and orientation of head and body.
Work Step by Step
UMNs from the cerebral cortex influence local circuits in the brain and spinal cord. They also influence upper motor neurons of the brain stem as well as lower motor neurons(LMNs) of the final common pathway. UMNs of the brain stem also influence local circuits, and the LMNs that form the final common pathway. The sites of origins of brainstem UMNs include the red nucleus, the vestibular nucleus, the superior colliculus and the reticular formation(RF).
