Anterior Horn CellsSpinal Muscular Atrophies of ChildhoodMuscular Atrophy, SpinalNeuronal Apoptosis-Inhibitory ProteinSMN Complex ProteinsSpinal CordSurvival of Motor Neuron 1 ProteinSpinal Cord DiseasesMuscular AtrophyMotor NeuronsElectromyographyHornsMusclesPosterior Horn CellsMenisci, TibialArthrogryposisNeuromuscular DiseasesParalysisMuscle ProteinsMuscle, SmoothMotor Neuron DiseaseMuscle, SkeletalMuscle Fibers, SkeletalMuscle, Smooth, VascularAmyotrophic Lateral SclerosisNeural ConductionSpinal Nerve RootsMuscle DevelopmentMuscle Contraction