Assertion: tract's axon | /r/CapableOf | descend into the brain stem
Facets:
value: to synapse on lower motor neurons
type: TRANSITIVE-OBJECT
Source sentences:
text: This system begins in the pyramidal cells of the primary motor cortex, and the axons of these upper motor neurons descend into the brain stem and spinal cord to synapse on lower motor neurons, depicted in red, that control skeletal muscles.