EMG & NCV & Biofeedback Test Questions and Answers

motor unit A motor neuron and all of the muscle fibers it innervates and composed of: 1. anterior horn cells 2. axon 3. neuromuscular junction 4. muscle fiber innervated by nerve motor neurons neurons that carry signals from the spinal cord to the muscles to produce movement MUAP the summation of electrical potential from all the fibers of that unit close enough to the electrode artifact unwanted electrical activity that arise outside the tissue bring examined True or False: the muscle should be relaxed during insertion of EMG needle True to avoid pain Spontaneous burst of Potential when insert needle are called - insertional activity, - cause: due to needle breaking through the muscle fibres membrane, - duration: last less than 300 milliseconds and described as: 1. normal 2. reduced 3. absent 4. prolonged or increased in normal relaxed muscle, followed the insertional activity is electrical silent, (absent of electrical potential) and if there is any activity in this period it indicates an abnormality after observing the muscle electrical silent activity, patient should contract the muscle minimally, and this weak contraction lead to individual motor unit contraction and characterize according to 1. amplitude (5-100 microvolt) 2. duration ( from time of onset to cessation of electrical potential =2-14 milliseconds) 3. shape (1-4 phases) 4. sound (clear distinct thump) 5. frequency after the minimal contraction phase, the patient should increase the level of contraction to the maximum to determine the recruitment pattern in the muscle: normally the number of motor unit contraction will increase until reaching the interference pattern (normally with maximum contraction) interference pattern (normally with maximum contraction)