The metamera is a fragment of the spinal cord that contains a pertinence and aforementioned of a nerve root. The metamera is a transverse segment of the medulla spinal which arise two bundles of nerve fibrils. These fibrils anastomosed and give rise to the left and right spinal nerves of the same level. Each of these nerves is related to a spinal ganglion and they give rise to two nerve roots, anterior and posterior. The metameras acting alone deal with reflex acts, which they do in partnership is thanks to Interneurons or association neurons.