Peripheral motor axons are the long neural tracts that connect the spinal cord to muscle. When the spinal cord is traumatized, these tracts can degenerate from lack of input and activation, leading them to become weak and inactive.
Using compound muscle action potentials, a tool that (in simple terms) measures the ability of the motor axon to activate when stimulated, a research team found significant decreases in remote peripheral nerves in spinal cord injury patients. These peripheral nerves included the abductor digiti minimi and the abductor hallucis. This decrease, however, could be significantly recovered within 5-12 months after injury.
Since recovery was associated with increased muscle strength, spinal cord injury rehabilitation efforts should focus on these specific peripheral nerves.
Van De Meent H, Hosman AJF, Hendriks J, Zwarts M, & Schubert M. Severe degeneration of peripheral motor axons after spinal cord injury: A European multicenter study. Neurorehabilitation and Neural Repair. (May 2010).