MODEL RELEASED. Laboratory test of a myoelectric" prosthetic arm. This artificial arm fitted with a hand and rotating wrist, is battery powered. It has electrodes which connect with the patient's skin at the site of amputation, and sense the electrical activity of the remaining arm muscle. These muscle signals are electronically amplified and are used to move the prosthetic arm and hand as required. It gives the user fine control over the limb, and the ability to use the arm slowly or quickly, with precision and varying strength. The "myoelectric" arm was developed at the University of Utah, USA. Here it is being tested in the Laboratories of Iomed Inc., Salt Lake City."