Step 1 → Neurology and Special Senses Motor Neuron and Motor PathwaysPreview this topic sectionPreview the conditions. Plans unlock the full Step 1 details when you need them. Free Biochemistry Free Microbiology Plans Motor Neuron and Motor Pathways conditions Amyotrophic Lateral Sclerosis Lower Motor Neuron Lesion Spinal Muscular Atrophy Upper Motor Neuron Lesion