A powered artificial substitute for a missing hand that may be attached to a natural arm or used as part of an upper-limb external prosthetic system, and is designed to replace the appearance and some of the function of the hand. The device features an integral or proximally mounted motor (e.g., electric, hydraulic) which actuates hand/finger movements (e.g., gripping, pinching, pointing). The control of movement is achieved through amplified muscle action potentials from voluntary contracting muscle in the residual limb/trunk, transmitted via surface electrodes in the device that make contact with the skin, which turn on the motor to provide a function.