The pyramidal decussation is the decussation of the corticospinal tract which connects the spinal chord with the motor cortex. The pathway starts in the motor cortex, passes through the internal capsule, cerebral peduncle, pons, and the medullary pyramids before getting to the pyramidal decussation, which connects motor neurons on one side of the body with the opposite cortical side. So the actual effect of decussation is connecting bodily areas with the opposite cortical areas.