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Motor neurons innervate muscle and are responsible motor function.Damage to axons of motor neurons,such as in peripheral nerve injury,results in degeneration of distal axons,denervation of muscle and loss of motor function.Peripheral nerve injury is common in patients with trauma.Recovery of muscular innervation and motor function is dependent on the correct regeneration of injured motor neurons.In the present presentation,we report our studies on how motor neurons respond to axonal injury in terms of neuronal survival and axonal regeneration,what mechanisms are underlying axonal regeneration and guiding axon growth to muscle.Spinal motor neurons die after axonal injury if the injured side is close to spinal cord and if there is not peripheral nerve component nearby.However,most motor neurons survive if a limit axon (> 2 mm in rats) remains after axonal injury.Injured motor neurons are able to regenerate their axons into the denervated muscle if a peripheral nerve graft is provided to bridge the gap due to injury.Schwann cells and neurotrophic factors produced by Schwanns cells play a critical role for axonal regeneration.Peripheral nerve graft from motor branch has a better effect for guiding motor axon regeneration.Motor neurons are also able to regenerate their axons into a biomaterial bridge if Schwanns cells are seeded in the bridge.Regenerated axons can reach their target muscle and re-innervate skeletal muscle fibers.They form new neuromuscular junction and restore motor function.In conclusion,spinal motor neuron are able to regenerate their axons after been injured.Schwann cells or/and neurotrophic factors play an important role for axonal regeneration.Regenerated axons are able to re-innervate muscles and restore motor function.