3.Degenerated fibers crossed to the opposite side in the pyramidal decussation and lay within the gray matter of the dorsal horn in segments C_1～C_5. In segment C_1 heavy degenerated fibers mainly distributed in laminae Ⅲ～V of the spinal cord.
4.Amyotrophic lateral sclerosis(ALS)) is one of the motor neural diseases, which selectively affects motor neurons in the anterior horn of spinal-cord, and the motor nuclei of brainstem and the pyramidal cells in the motor cortex of brain.
