The motoneuronal outputs from cortex and spinal cord have quite different patterns of organisation. The cortex consists of a highly intermixed mosaic of small output zones whereas the motoneurones in the cord are located in clearly defined columns of cells, that all project to the same muscle. I describe the pattern of innervation between cortex and cord, indicate the importance of cortical plasticity in allowing flexible control of spinal circuits, and show how these inputs interact. Finally I discuss some of the new methods of stimulating descending motor pathways in humans.