From the Greek and meaning “around”, or away from the centre, this word refers to those parts of the nervous system that lie outside the head and spine or, more accurately, outside the brain and the spinal cordThe main nerve trunk running down the spinal canal and connecting the individual’s mind and consciousness to the rest of his or her body. It is about the size of a person’s little finger, in diameter. It cannot repair itself if damaged.. Together they constitute the peripheral nervous system, which itself is made up of sensory nerves, nerves controlling motor functionsBy these we are referring to voluntary muscle or limb movements, including strength, co- ordination, dexterity and gait (walking). Eye movements, speaking, swallowing and breathing are also motor functions. and autonomicThat part of the nervous system that controls processes that are not under voluntary control, such as sweating, responses to exercise and digestive processes. components.