Motor systems II: Descending (cortical) systems
Summary view of descending pathways, showing multiple projections and different laminar locations of cortical output neurons. Note that superficial cortical laminae (II, III) project to other cortical areas, whereas deep cortical laminae (V, VI) give rise to descending projections, both pyramidal and extrapyramidal. Lamina IV (granule layer) is poorly developed in most parts of primary and secondary motor cortex.