ICD-10-CM > M00-M99 > M60-M63 > M63 > M63.8 > M63.83 M63.83 Disorders of muscle in diseases classified elsewhere, forearm Non-Billable/Non-Specific Codes M63.831Disorders of muscle in diseases classified elsewhere, right forearmM63.832Disorders of muscle in diseases classified elsewhere, left forearmM63.839Disorders of muscle in diseases classified elsewhere, unspecified forearm