Most nerve impulses move up spinal cord to brain and back down thru spinal cord to peripheral nerves…however, some merely enter thru dorsal root of cord, synapse, and exit thru ventral root of cord. (ie. the knee jerk reflex)
-Intact cord have message sent to brain at same time
-Some SCI have reflexes without voluntary muscle control (UMN) and some don’t have any reflexes below level of injury (LMN)
Reflex Arc