The technical term for the way of assessing the muscle contraction is called acceleromyography (AMG). AMG relies on 2 stimulating electrodes usually placed along the ulnar nerve at the wrist and a sensor that is placed in the groove between the thumb and the index finger; the sensor detects the acceleration of movement (bending) that is produced by the thumb in response to electrical stimulation of the ulnar nerve (TOF-Watch® SX Monitor). When the thumb contracts and accelerates the piezoelectric sensor, the degree of movement is sensed, and it is converted into electrical signals that are proportional to the force of thumb contraction. AMG can yield signals that can be measured and that can give an indication of the degree of neuromuscular block.