Flail limb

A flail limb, or "flail arm", is a medical term which refers to an extremity in which the primary nerve has been severed, resulting in complete lack of mobility and sensation. Although blood typically continues to flow through the limb, it is completely useless and generally cannot be surgically repaired. The muscles soon wither away from atrophy, and the arm swings loosely at the side like a literal "dead weight."