Layer V cells project via long axons to the spinal cord. To red nucleus, b. Functionally the CST is most importantly involved in fine or precise movement of the distal muscles. The motor cortex is topographically organized. Each CST axon has many collaterals that may influence several muscles.
Distal muscles are over represented.
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.