The CNS communicates with peripheral body structures through pathways. These conduct either sensory nerve signals from or motor nerve signals to ; processing and integration occur along them. These pathways travel through the white matter of the spinal cord as they connect various CNS regions with spinal nerves. A pathway consists of a(n) (groups or bundles of axons that travel together in the CNS) and a(n) nucleus (a collection of neuron cell bodies located within the CNS).