Motor birimler ve bunların elektromiyogramlarla ilişkisi
Motor birim::
Tek bir motor nöron ve onun aksonu birçok kas lifini donatır. Bir motor nöronun dallarla birlikte tek aksonu aracılığıyla donattığı kas liflerine motor birim denir. Bir motor birimdeki kas lifi sayısı değişkenlik gösterir. Kedi bacak kaslarında bir motor birimde yaklaşık 120-165 lif olduğu gözlenmiştir.
Elektromiyografi:
Motor birim aktivitesi, çalışılacak kasa bir koaksiyel elektrot yerleştirilerek ölçülür. Daha sonra elektrot bir elektromiyografa bağlanır ve kas aktivitesi sırasında elektromiyogram adı verilen bir kayıt alınır.
İçi boş bir iğne, içine yalıtılmış bir iç tel sokularak bir koaksiyel elektrot haline getirilebilir. İğne ucunun hemen yakınındaki küçük kas hacimlerinden değişiklikler kaydedilir. Dolayısıyla, en yüksek elektriksel aktivite elektrotların yakınındaki aktif liflerde gözlenir. Bazen derin kas koaksiyel elektrotları yerine yüzey elektrotları kullanılır. Bu kayıt yönteminde, çalışılacak kas üzerine uygun bir mesafeden iki yüzey elektrodu yerleştirilir.
Dinlenme halindeki kasta aksiyon potansiyeli kaydedilmez; ancak kas aktif hale gelir gelmez, , elektrotların yakınındaki motor nöronlardaki asenkron deşarj aksiyon potansiyeli oluşturur. Minimum istemli aktivite sırasında, sadece birkaç motor birimde boşalma gözlenir ve istemli aktivite arttıkça daha fazla birim aktive olur. Bu, motor birim katılımı olarak adlandırılır.
Kas aktivitesinin derecelendirilmesi, aktive edilen motor birim sayısının bir fonksiyonudur. Elektromiyografik çalışmalar, periferik sinir yaralanmaları ve miyotoni ve myastenia gravis dahil nöromüsküler bozukluklar gibi motor birim bozukluklarının tanısında klinik olarak önemlidir.
Motorunit’s relation with electromyogram (EMG)
Motorunit:
A single motor neuronmotoneuronand it’s axonaxons innervate1supply not onlyjust a muscle fiber, but also several muscle fibers. The mMusclefibersthatis supplied innervated by one motor neuron throughits single axon along with branches are called a MmotorUunit.ThenumberA variety of musclefibers ina motor unit variesare present2 .It is has been observedin cat leg muscles that approximately 120–, 165fibers are present in one motor unit.
EMG
A motor unit
activity is measured through inserting3 a coaxial electrode in tothe muscle that is to be studied. Next, theelectrode isthey areconnected to an electromyographelectromyography(EMG)4. A recording is obtained during muscular activity. Thisrecording is called an electromyogram (EMG).
A hypodermic hollow5needle can be made in to a coaxial electrode by introducing aninsulated inner wire with in into it. Possiblechanges are recorded from small volume of the muscles in immediate neighbourhoodof the tip of the needle. Thus, it is has been observed that most of theelectrical activity is from the active fibers near the electrodes. Sometimes,surface electrodes is used instead of deep muscle coaxial electrode. In thisrecording method, two surface electrodes are placed over the muscle to bestudied at a reasonable distance.
When themuscle is at rest, no action potential is recorded; however, as soon as themuscle becomes active, action 6potentials are recorded. Thepotential recorded during activity is as a result of the asynchronous dischargeof motoneurons in the vicinity of the electrodes. During minimal voluntaryactivity, only a few number of motor units aredischargeddischarges, and as voluntary effort activity increases,the morenumberof units areis activated.This is called recruitment of motor units.7
Gradation ofmuscular activity is a function of thea part of thefunction of a number of motor units activated. Electromyographic8Electrographic studies have clinicallyimportance in diagnosis of motor unit disorders including peripheral nerveinjuries, neuromuscular disorders such as myotonia and myasthenia gravis, so onand so forth.
Motor unit’s and their relationwith electromyograms (EMG)1
Motor unit :
A single motor neuronmotoneuronand its it’s2axonaxonsinnervate3supply not onlyjust a muscle fiber, but also several muscle fibers; these fibers constitute The mMuscle fibersthatis supplied innervated by one motor neuron throughits single axon along with branches are called MmotorUunit.The numberA variety of musclefibers ina motor unit variesare present4 .It The motor unit of cat legmuscles is has been observedin that hasapproximately 120–, 165 fibers are present in one motor unit5.
Electromyography: EMG
A Mmotor unit activity is recorded by measured throughinserting6a coaxial electrode in to the muscle of interest that isto bestudied. Next, the electrode isthey areconnected to an electromyographelectromyography(EMG)7. A and a recording isobtained during of muscularactivity. knownas an electromyogram is obtained. Thisrecording is called an electromyogram (EMG).8
A hypodermic hollow9 needlecan be made in to converted into a coaxial electrode by introducingan insulated inner wire with in into it. Possible Cchangesare recorded from the small volume of themuscles are recorded in the immediate vicinityneighbourhood of the tip of the needle tip.Thus, it is has been observed that most the highest ofthe electrical activity is observedfrom inthe active fibers near the electrodes. Sometimes, surface electrodes are is10used instead of deep muscle coaxial electrodes.In this recording method, two surfaceelectrodes are placed at a reasonable distance onthe skin overlying over themuscle to be studied at a reasonable distance.
When themuscle is at rest, no action potential is recorded;11 however, as soon as themuscle becomes active, action potentials results fromare recorded. The potential recorded duringactivity is as a result of the asynchronous discharge of motor neurons12motoneuronsin the vicinity of the electrodes. During minimal voluntary activity, only afew numberof motor units are dischargeddischarges,and as voluntary effort activity increases,the morenumberof units areis activated.This is called motor unit recruitment of motor units.13
The Ggradation of muscular activity is a functionof thea part of the function of anumber of activated motor units activated. Electromyographic Electrographic14studies are clinically importanthave clinically importance in the diagnosis of motor unit disorders, including peripheral nerve injuries, and neuromuscular disorders, such asincluding myotonia and myasthenia gravis, so on and so forth15.
Motor units and their relation with electromyograms
Motor unit:
A single motor neuron and its axon innervate several muscle fibers; these fibers constitute a motor unit. The number of muscle fibers in a motor unit varies. The motor unit of cat leg muscles has approximately 120–165 fibers.
Electromyography:
Motor unit activity is recorded by inserting a coaxial electrode into the muscle of interest. Next, the electrode is connected to an electromyograph and a recording of muscular activity, known as an electromyogram, is obtained.
A hypodermic needle can be converted into a coaxial electrode by introducing an insulated inner wire into it. Changes from the small volume of muscles are recorded in the immediate vicinity of the needle tip. Thus, the highest electrical activity is observed in the active fibers near the electrodes. Sometimes, surface electrodes are used instead of deep muscle coaxial electrodes. In this method, two surface electrodes are placed at a reasonable distance on the skin overlying the muscle to be studied.
When the muscle is at rest, no action potential is recorded; however, as soon as the muscle becomes active, action potential results from the asynchronous discharge of motor neurons in the vicinity of the electrodes. During minimal voluntary activity, only a few motor units are discharged, and as voluntary activity increases, more units are activated. This is called motor unit recruitment.
The gradation of muscular activity is a function of the number of activated motor units. Electromyographic studies are clinically important in the diagnosis of motor unit disorders, including peripheral nerve injuries, and neuromuscular disorders, including myotonia and myasthenia gravis.
