CST fibers arising from the primary motor cortex plays a preeminent role in controlling distal muscles. Functional relationships of the corticospinal tract. Proximal muscles can still be made to contract but with higher stimulation currents. Efferents of the premotor cortex are mainly to the medullary reticular formation and from there to the spinal cord. The supplementary and primary motor cortex project directly to the spinal cord.
Voluntary movements require a plan of action.
The supplementary motor cortex and premotor cortex produce movements and contractions following stimulation and are somatotypically organized. These movements are often bilateral following stimulation of the supplementary motor cortex. The supplementary and premotor cortices receive inputs from areas 5 and 7. Area 5 receives input from the somatosensory cortex and area 7 receives visual inputs. Both the supplementary motor cortex and the premotor cortex project somatotypically to the primary motor cortex.