• Degenerative: Endomysial Fibrosis; Disuse Atrophy; Juvenile/Adult Spinal Muscular Atrophy; Myotonia
• Developmental: Dystrophinopathies (i.e. Muscular Dystrophies: BMD, DMD, EMD); Congenital myopathies: Ion channel dysfunction; Nemaline myopathy, Fibrodysplasia Ossificans Progressiva; Autophagic Vacuolar Myopathy

A

• Autoimmune: Polymyositis, Myasthenia Gravis; Immune Mediated Necrotizing Myopathy
• Anomalies: Anomalous T Tubule Network; Absent Muscles (associated with CHARGE syndrome); Structural Differences (origin/insertion); Presence of Peroneous Quartus Muscle (associated with peroneous longus and brevis)

M

• Metabolic: Metabolic Myopathies: Inborn Errors of Metabolism (glycogen); Mitochondrial Myopathies; Acid Maltase Deficiency, Carnitine Palmityl Transferase Deficiency; Myoadenylate Deaminase Deficiency; Debrancher Enzyme Deficiency; Phosphoglycerate Kinase Deficiency; Ion changes (Hypokalemia, Hypocalcemia, Hypernatremia); Hyperkalemic periodic paralysis; Hyper- & Hypo thyroidism; Hyper- & Hypo- adrenocorticism; Primary hypoparathyroidism; Lipid Storage myopathy
• Mechanical: Rhabdomyolitis

N

• Neoplastic: Rhabdomyosarcoma; Large Cell Lymphoma, Fibrosarcoma, Malignant Fibrous Histiocytoma
• Nutritional: Selenium Deficiency; Starvation (Anorexia, Bulemia)
• Neurologic: Muscle Fiber Atrophy, Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease); Charcot-Marie Tooth Disease; DeJerine-Sottas Disease; Friedreich's Ataxis

I

• Inflammatory: Dermatomyositis, Inclusion Body Myositis; Polymyositis
• Infectious: Lyme Disease (Borrelia); Influenza, Herpes, Legionella, Salmonella, Poliovirus; Toxoplasmosis; Trichenella
• Idiopathic: Fibromyalgia; Myotonia; Myofascial Pain Syndrome

T

• Trauma: Rhabdomyolysis, Cerebral Palsy, Compartment Syndrome, Ruptured Tendon
• Toxin: Toxic Myopathies (Thyrotoxic, Ethanol, Statin Drugs)
• Temperature: Central Core Disease (Malignant Hyperthermia)

V

• Vascular: Aquired Metabolic Myopathy secondary to atherosclerosis; Ischemic myopathy