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A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. [1] It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. [2] Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy.
Myasthenia gravis most commonly occurs in women under the age of 40 and in men over the age of 60. [1] [5] [14] It is uncommon in children. [1] With treatment, most live to an average life expectancy. [1] The word is from the Greek mys, "muscle" and asthenia "weakness", and the Latin gravis, "serious". [15]
At the nerve ending in the neuromuscular junction, where the impulse is transferred to the muscle cell, the nerve impulse leads to the opening of voltage-gated calcium channels (VGCC), the influx of calcium ions into the nerve terminal, and the calcium-dependent triggering of synaptic vesicle fusion with plasma membrane.
Upper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex and brainstem and carry information down to activate interneurons and lower motor neurons, which in turn directly signal muscles to contract or relax.
Neuromuscular junction diseases in this category include snake venom poisoning, botulism, arthropod poisoning, organophosphates and hypermagnesemia.(reference 13) Organophosphates are present in many insecticides and herbicides. They are also the basis of many nerve gases.(reference 27) Hypermagnesmia is a condition where the balance of ...
A neuronopathy affects the cell body of a nerve cell in the peripheral nervous system. [5] Amyotrophic lateral sclerosis; Spinal muscular atrophy; Spinal muscular atrophy with respiratory distress type 1; Atypical motor neuron diseases; Dorsal root ganglion disorders
Women’s bodies go through many changes in menopause and the years leading up to it, known as perimenopause. This natural step in the aging process marks the end of the reproductive years. In ...
Repetitive nerve stimulation is a variant of the nerve conduction study where electrical stimulation is delivered to a motor nerve repeatedly several times per second. By observing the change in the muscle electrical response (CMAP) after several stimulations, a physician can assess for the presence of a neuromuscular junction disease, and differentiate between presynaptic and postsynaptic ...