Spinal root nerves. Coloured scanning electron micrograph (SEM) of a sectioned spinal root nerve bundle, showing individual axons, extensions of nerve cells). Spinal root nerves are bundles of nerves that connect the spinal cord (part of the central nervous system, CNS) with the neural network in the rest of the body. Like all nerves outside the CNS, they are part of the peripheral nervous system (PNS). Axons are extensions of nerve cells, transmitting nerve impulses between the nerve cell bodies. Magnification: x1600 when printed at 10 centimetres wide.