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1、第4课 肌电测量及仪器（Fourth lesson EMG measurement and instrument）The fourth class of EMG measurement and instrument.Txt if the heart is clean, one world, a bird and a heaven. I used to love you, now I still love you want to get to where the moon can leave you smile those snowy winter, the umbrella of youth,
2、 that is blocking the door to the oath, the string of snow covered goodbye bio electrical measurement and instrument - EMG measurement and instrumentLouis LiuQSchool of life science and technology, Huazhong University of Science and TechnologyBIoMedical, Measurements, and, Instrumentation (BMI)conte
3、ntBioelectric potential in muscle cellsEMG guidance and recordingThe structure and index of typical electromyographyElectromyographyMuscle systemThe muscle is connected by muscle cells through connective tissue, and the ends are connected with the tendonEach muscle is attached to the bones and other
4、 connective tissues and, under the management of the nervous system, constitutes a mechanical effector system that performs certain motor functions.Skeletal muscle structure pattern0.010.1cmBioelectric potential in muscle cellsExcitation and contraction are the basic functions of skeletal muscles an
5、d the basis of EMG production. Electromyogram is the record of the change of skeletal muscle potential under different functional status.Changes in the recording potential of skeletal muscles are related to muscle structure, contractile mechanics, and chemical changes during contraction.Electromyogr
6、aphy is the technique of recording the electrophysiological properties of muscle during quiet and voluntary contraction and stimulation of the peripheral nerveBioelectric potential in muscle cells4 kinds of bioelectric potential of muscle cell weight:Resting potential (Resting, Potential, RP): trans
7、membrane potential, the resting potential of frog skeletal muscle cells ranged from -50 to -70mV, and the muscle and nerve cells in mammals ranged from -70 to -90mVAction potential: the potential that occurs when the membrane potential is depolarized and repolarization and transmitted around. The du
8、ration is 0.51ms.-90mV0mV+40mV+30mV0.51msBioelectric potential in muscle cells4 kinds of bioelectric potential of muscle cell weight:End plate potential: the mammalian neuromuscular junction is a plate joint (motor end plate), and the motor end plate has spontaneous potential, EPP (End Plate, Potent
9、ial). EPP is caused by depolarization of the motor end plate by acetylcholine, and the amount of EPP that is synchronized near the sum of the above exceeds the critical potential, causing action potential (local, not propagating)Injury potential (Injury potential, IP): somewhere such as muscle damag
10、ed, will cause the damage of membrane polarization weakened or disappeared, so the damage on the surface of the organization (-) and (+) surface integrity of the Department will have a potential difference between the potential of IP.EMG formation principleThe EMG signals originate from motor neuron
11、s in the spinal cord, part of the central nervous system, and the motor neuron axons extend to the muscle fibers and are coupled with the muscle fibers through the endplate region. Neurons and muscle fibers constitute the motor unit.From the brain excited conduction down, motor neurons generate acti
12、on potentials, along the axon to peripheral motor endplates and muscle, the action potential to release acetylcholine, acetylcholine causes endplate ion permeability changes, the potential to produce endplate potentials, muscle cell depolarization and action potential of muscle fibers, and along mus
13、cle fiber spreading to both sides, the changes occur within muscle fiber contraction, a large number of muscle fiber contraction of muscle forceEMG formation principleEMG measurement history1791 Galvani through the contraction of frog muscle, muscle contraction and electric proof are closely related
14、, is the earliest recognition of EMGIn 1851, the French Dubois-Reymond first detected the electrical signals produced by contraction of the human bodys musclesIn 1907, Piper potential using string galvanometer record to the arm musclesEMG measurement historyIn 1922, Gasser and Erlangre observed the
15、EMG with a cathode ray oscilloscope and won the 1944 Nobel prizeSciatic, Nerve, Action, Potential, from, Gasser & Erlanger, Am, J, Physiol, 62:, 496-524, 1922Herbert Gasser1874-1965Joseph Erlanger1888-1963EMG guidance and recordingEMG electrodeNeedle electrodeUnipolar concentric needle electrode, bi
16、polar concentric needle electrode, and multi concentric needle electrodePlatinum wire material is inserted into the muscle to guide the EMG signal after disinfectionAnalysis of motor unit potentialSurface electrodeSilver and stainless steel are used as materials to be placed on the surface of the sk
17、in, and the electrical activity of the lower part of the electrode is measured without any damageThe utility model is suitable for the change of muscle during the evoked potential or movement, and leads to the combined potential of a plurality of muscle fibers, and can not be used as a motion unit p
18、otential analysisMonopolar NeedlesModern Concentric NeedleRecording, Intramuscular, EMG, Signals, Using, Surface, ElectrodesRehabilitation, Institute, of, Chicago, ChicagoNikolay, S., Stoykov, Madeleine, M., Lowery, et, AlElectromyogram instrumentElectromyographic EMG (Electromyography) is the recor
19、ding of physiological electrical signals produced by the muscles. It can be measured by the surface electrodes placed on the skin, or by the insertion of needle electrodes through the skin. The magnitude of the EMG is related to the location of the electrodes, with a range of about 20 V50mV and a ba
20、ndwidth of 205000Hz.EMG consists of electrodes, preamplifier and main amplifier, oscillograph, waveform display and recorder. Modern EMG apparatus is often combined with an evoked potential instrument, controlled by a microcomputer, is a pen free recording type, uses a television monitor to display
21、the waveform, and a waveform is printed by a hot array printer or a laser printer.Electro = electricityMyo= muscleGraphy= drawing or recordingSystem diagram of EMG measurementTypical EMG amplifier filter circuitEMG characteristics: 20 V50mV, bandwidth 205000Hz (with the anatomy of the muscle, the ty
22、pe of electrode, size and location)Electromyograph circa 1946 with 35 mm recordingCamera, and, loudspeaker, from, Huddleston & GolsethArch, Phys, Med, 29:92-98, 1948The structure of typical electromyographyElectromyogram instrumentThe EMG instrument above can acquire and measure spontaneous EMG and
23、evoked EMG signals in real time and under stimulation. The electrodes in the diagram can be made of two types of electrodes: needle electrodes and surface electrodes.Needle electrodes are used to record the action potentials of the motor units for clinical diagnosis of neuromuscular diseases; surfac
24、e electrodes are used to understand the kinematics of the whole muscle activity.Typical EMG indicators (1)Preamplifier noise: should be less than 5uV.Sensitivity: 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000uV / cmScanning speed: 1, 2, 5, 10, 20, 50, 100, 200ms / cmStimulation frequency: 0.
25、2, 0.5, 1, 2, 5, 10, 20, 50HzPulse duration (duration):0.1, 0.2, 0.5, and 1msStimulus range: * 1, 050V, x 10, 0500Computer functions: recording, stacking, signal delay and conduction velocity calculationIndexes of typical electromyography (two)Stacking times: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, a
26、nd 1024.Recording speed: 1. Real time record: 25, 50, 100, 250, 500 mm/s, memory record: 20 m/s single.Record content: real record: two line signal, time scale, sensitivity, speed, patient records: single; the two line signal, time scale, patient, sensitivity, scanning speed, distance, stimulus late
27、ncy and conduction velocity etc.In line with the national medical general electric safety standard GB9706.1Specific safety standard for international EMG evoked potential IEC60601-2-40Abnormal electromyogramThe beam tremor potential consisted of two groups: simple beam frontal potential and compound
28、 beam frontal potentialSimple twitch potential is an action potential of a single motor potential of the anterior horn cell or external nerve lesionThe complex beam quiver potential is the action potential of polyphase motion when the synchronous excitation of the muscle fiber group belongs to a sin
29、gle motion unit.Single motor unit potentialSimple twitch potentialCompound beam flutter potentialAbnormal electromyogramFibrillation potentials, including evoked and spontaneous fibrillation potentials, are two types of motor neuron degeneration or injury, and fibrillation potential is easily produc
30、ed by denervation of muscle fibers.When the denervated muscle fibers relax, the positive phase waves of the denervated muscle fibers are often accompanied by fiber potentials, which are called positive sharp wavesFibrillation potentialPositive sharp waveEvoked electromyographyReflex electromyography
31、Under different frequency and intensity stimulation, the waveform, stimulation threshold and latency (M wave) of the muscle evoked potential were observedAfter the electric stimulation of the peripheral nerve, the M wave is evoked by the EMG, and the reflected wave (H wave) appearsH wave is an impor
32、tant index to detect the wind in the anterior horn of spinal cord,H/M ratio is one of the important indexes of the diagnosis of upper motor neuron lesion, and the normal value is 0.650.75Evoked electromyographyDetermination of nerve conduction velocityWith pulse duration of 0.20.5ms short pulse by p
33、utting in a cover on the skin above the nerve above the electrodes on the skin to stimulate the nerve, which is caused by impulses in nerve fibers, when excited to the muscles, muscle is a short contracture, will produce EMG signal.Nerve damage, slow, or even complete loss of conduction. The normal
34、speed is 50m/s, if lower than 40m/s, it is pathological. For example, complete paralysis of the nerve, 0m/s speed, nerve impulse can not be transmittedNerve regeneration can restore conductionSurface EMG parameterDifferential Electrode Configuration:Detection, surfaces, two, parallel, bars, 1, cm, a
35、partBandwidth of 20-500HzCommon, Mode, Rejection, Ratio 80 dBNoise 100 MegaOhmsA, Classification, Method, of, Hand, Movements, Using, Multi, Electrode, ChannelKentaro NAGATA, 900. JapanMulti-channel signal analysisApplication of electromyographyElectromyography is of great value in the differential
36、diagnosis of neurogenic and myogenic diseases, as well as in the location, extent of damage and prognosis of neuropathy:Neurogenic disease: peripheral neuropathy (including diabetes, alcoholism, uremia) cervical disease, venereal disease, paralysis of moving element facial paralysis, polyneuritis, s
37、pinal cord lesions, demyelinating disease, cross paralysis and diagnosis of neurogenic sexual dysfunction etc.Myogenic disorders: muscular dystrophy, muscle atrophy, periodic paralysis, myasthenia gravis, myotonic syndrome, nerve and muscle joint disease.Connective tissue disease, polymyositis, derm
38、atomyositis, multiple sclerosis, systemic lupus erythematosus disease, disuse muscular atrophy, rheumatoid arthritis and other diseases.Application of electromyographySports ResearchQuantitative relationship between muscle strength and electromyographyThe amplitude and frequency of EMG changes durin
39、g muscle fatigue under the same working loadStudy the coordination ability of muscle movement: the athletes with the training level discharge the muscles neatly and have certain regularity when they perform the same actionApplication of electromyographyMan-machine intelligent systemHAL-3/HAL-5 devel
40、oped by University of Tsukuba, Japan, uses sEMG signals as feedback control signals, adjusts the exoskeleton torque, and achieves the purpose of power assistanceIn the prosthetic system, the EMG is applied to the prosthetic hand as the control signal source, and the prosthesis is realized according to the human consciousnessTwo. Exercise unit (MU)NConcept: a motor unit, a muscle fiber that is dominated by an anterior horn cell and its axon, is the smallest functional unit of muscle contraction.NMotor unit size (innervation ratio): related to fine movements of muscle.