English: The TOF-Watch is an acceleromographic quantitative neuromuscular function monitor. It may be used to assess the effects of muscle relaxants when used as part of general anaesthesia. The black negative stimulating electrode is placed over the distal part of the ulnar nerve and the white positive electrode 3 cm proximally over the same nerve. A piezoelectric crystal is placed on the thumb and acceleration of the crystal caused by contraction of the muscle when the nerve is stimulated generates a voltage that is proportional to the force of the muscle contraction. Force = mass X acceleration.Quantitative neuromuscular monitors can assess the depth of neuromuscular blockade and exclude the residual effects of muscle relaxants when used in combination with general anaesthesia.