Biomaterial Database

Variation of motor unit size in the human extensor digitorum brevis and thenar muscles. 1974

T E Feasby, and W F Brown

One physiological method for estimating the motor unit number in a muscle depends on dividing into the maximum compound muscle action potential, the potential average of the first few motor unit potentials excited by a motor nerve stimulus above motor threshold. To be valid, such an average unit potential size must be representative of the whole motor unit population. This assumption may not be justified. The present study has shown that there are single motor units in healthy and abnormal, thenar, and EDB motor unit populations, many times larger than any motor unit excited close to the motor threshold. This finding suggests that previously reported motor unit estimates may not only be an overestimate of the true motor unit population number, but have excluded much larger motor units with higher thresholds. Low motor unit estimates in neuropathies may result from a change in the order of activation of motor units with the appearance of larger motor units, normally of higher threshold among the first few just above the motor threshold.

UI	MeSH Term	Description	Entries
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009223	Myotonic Dystrophy	Neuromuscular disorder characterized by PROGRESSIVE MUSCULAR ATROPHY; MYOTONIA, and various multisystem atrophies. Mild INTELLECTUAL DISABILITY may also occur. Abnormal TRINUCLEOTIDE REPEAT EXPANSION in the 3' UNTRANSLATED REGIONS of DMPK PROTEIN gene is associated with Myotonic Dystrophy 1. DNA REPEAT EXPANSION of zinc finger protein-9 gene intron is associated with Myotonic Dystrophy 2.	Dystrophia Myotonica,Myotonic Dystrophy, Congenital,Myotonic Myopathy, Proximal,Steinert Disease,Congenital Myotonic Dystrophy,Dystrophia Myotonica 1,Dystrophia Myotonica 2,Myotonia Atrophica,Myotonia Dystrophica,Myotonic Dystrophy 1,Myotonic Dystrophy 2,PROMM (Proximal Myotonic Myopathy),Proximal Myotonic Myopathy,Ricker Syndrome,Steinert Myotonic Dystrophy,Steinert's Disease,Atrophica, Myotonia,Atrophicas, Myotonia,Congenital Myotonic Dystrophies,Disease, Steinert,Disease, Steinert's,Dystrophia Myotonica 2s,Dystrophia Myotonicas,Dystrophica, Myotonia,Dystrophicas, Myotonia,Dystrophies, Congenital Myotonic,Dystrophies, Myotonic,Dystrophy, Congenital Myotonic,Dystrophy, Myotonic,Dystrophy, Steinert Myotonic,Myopathies, Proximal Myotonic,Myopathy, Proximal Myotonic,Myotonia Atrophicas,Myotonia Dystrophicas,Myotonic Dystrophies,Myotonic Dystrophies, Congenital,Myotonic Dystrophy, Steinert,Myotonic Myopathies, Proximal,Myotonica, Dystrophia,Myotonicas, Dystrophia,PROMMs (Proximal Myotonic Myopathy),Proximal Myotonic Myopathies,Steinerts Disease,Syndrome, Ricker
D011128	Polyradiculopathy	Disease or injury involving multiple SPINAL NERVE ROOTS. Polyradiculitis refers to inflammation of multiple spinal nerve roots.	Polyradiculitis,Polyradiculopathy, Abdominal,Abdominal Polyradiculopathies,Abdominal Polyradiculopathy,Polyradiculitides,Polyradiculopathies,Polyradiculopathies, Abdominal
D011164	Porphyrias	A diverse group of metabolic diseases characterized by errors in the biosynthetic pathway of HEME in the LIVER, the BONE MARROW, or both. They are classified by the deficiency of specific enzymes, the tissue site of enzyme defect, or the clinical features that include neurological (acute) or cutaneous (skin lesions). Porphyrias can be hereditary or acquired as a result of toxicity to the hepatic or erythropoietic marrow tissues.	Porphyria,Porphyrin Disorder,Disorder, Porphyrin,Disorders, Porphyrin,Porphyrin Disorders
D003929	Diabetic Neuropathies	Peripheral, autonomic, and cranial nerve disorders that are associated with DIABETES MELLITUS. These conditions usually result from diabetic microvascular injury involving small blood vessels that supply nerves (VASA NERVORUM). Relatively common conditions which may be associated with diabetic neuropathy include third nerve palsy (see OCULOMOTOR NERVE DISEASES); MONONEUROPATHY; mononeuropathy multiplex; diabetic amyotrophy; a painful POLYNEUROPATHY; autonomic neuropathy; and thoracoabdominal neuropathy. (From Adams et al., Principles of Neurology, 6th ed, p1325)	Diabetic Amyotrophy,Diabetic Autonomic Neuropathy,Diabetic Neuralgia,Diabetic Polyneuropathy,Neuralgia, Diabetic,Asymmetric Diabetic Proximal Motor Neuropathy,Diabetic Asymmetric Polyneuropathy,Diabetic Mononeuropathy,Diabetic Mononeuropathy Simplex,Diabetic Neuropathy, Painful,Mononeuropathy, Diabetic,Symmetric Diabetic Proximal Motor Neuropathy,Amyotrophies, Diabetic,Amyotrophy, Diabetic,Asymmetric Polyneuropathies, Diabetic,Asymmetric Polyneuropathy, Diabetic,Autonomic Neuropathies, Diabetic,Autonomic Neuropathy, Diabetic,Diabetic Amyotrophies,Diabetic Asymmetric Polyneuropathies,Diabetic Autonomic Neuropathies,Diabetic Mononeuropathies,Diabetic Mononeuropathy Simplices,Diabetic Neuralgias,Diabetic Neuropathies, Painful,Diabetic Neuropathy,Diabetic Polyneuropathies,Mononeuropathies, Diabetic,Mononeuropathy Simplex, Diabetic,Mononeuropathy Simplices, Diabetic,Neuralgias, Diabetic,Neuropathies, Diabetic,Neuropathies, Diabetic Autonomic,Neuropathies, Painful Diabetic,Neuropathy, Diabetic,Neuropathy, Diabetic Autonomic,Neuropathy, Painful Diabetic,Painful Diabetic Neuropathies,Painful Diabetic Neuropathy,Polyneuropathies, Diabetic,Polyneuropathies, Diabetic Asymmetric,Polyneuropathy, Diabetic,Polyneuropathy, Diabetic Asymmetric,Simplex, Diabetic Mononeuropathy,Simplices, Diabetic Mononeuropathy
D004576	Electromyography	Recording of the changes in electric potential of muscle by means of surface or needle electrodes.	Electromyogram,Surface Electromyography,Electromyograms,Electromyographies,Electromyographies, Surface,Electromyography, Surface,Surface Electromyographies
D006429	Hemiplegia	Severe or complete loss of motor function on one side of the body. This condition is usually caused by BRAIN DISEASES that are localized to the cerebral hemisphere opposite to the side of weakness. Less frequently, BRAIN STEM lesions; cervical SPINAL CORD DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; and other conditions may manifest as hemiplegia. The term hemiparesis (see PARESIS) refers to mild to moderate weakness involving one side of the body.	Monoplegia,Hemiplegia, Crossed,Hemiplegia, Flaccid,Hemiplegia, Infantile,Hemiplegia, Post-Ictal,Hemiplegia, Spastic,Hemiplegia, Transient,Crossed Hemiplegia,Crossed Hemiplegias,Flaccid Hemiplegia,Flaccid Hemiplegias,Hemiplegia, Post Ictal,Hemiplegias,Hemiplegias, Crossed,Hemiplegias, Flaccid,Hemiplegias, Infantile,Hemiplegias, Post-Ictal,Hemiplegias, Spastic,Hemiplegias, Transient,Infantile Hemiplegia,Infantile Hemiplegias,Monoplegias,Post-Ictal Hemiplegia,Post-Ictal Hemiplegias,Spastic Hemiplegia,Spastic Hemiplegias,Transient Hemiplegia,Transient Hemiplegias