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Signal transmission from nerve to muscle at the motor end plate. The neuromuscular junction is the synapse that is formed between an alpha motor neuron (α-MN) and the skeletal muscle fiber. In order for a muscle to contract, an action potential is first propagated down a nerve until it reaches the axon terminal of the motor neuron.
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 .
As a result, normal functioning can be completely or partially inhibited, with the symptoms largely presenting themselves as problems in mobility and muscle contraction as expected from disorders in motor end plates. Neuromuscular junction diseases can also be referred to as end plate diseases or disorders. [citation needed]
A neuroeffector junction is a site where a motor neuron releases a neurotransmitter to affect a target—non-neuronal—cell. This junction functions like a synapse . However, unlike most neurons, somatic efferent motor neurons innervate skeletal muscle, and are always excitatory.
A single motor neuron may innervate many muscle fibres and a muscle fibre can undergo many action potentials in the time taken for a single muscle twitch. Innervation takes place at a neuromuscular junction and twitches can become superimposed as a result of summation or a tetanic contraction. Individual twitches can become indistinguishable ...
Groups of motor units often work together as a motor pool to coordinate the contractions of a single muscle. The concept was proposed by Charles Scott Sherrington. [2] Usually muscle fibers in a motor unit are of the same fiber type. [3] When a motor unit is activated, all of its fibers contract.
The ability of a motoneuron to branch at the neuromuscular junction represents the pre-synaptic plasticity of the motor unit. The ability of acetylcholine receptors to increase and decrease in number on the motor end plate of the effector muscle represents the post-synaptic plasticity of the motor unit. Studies have shown that with increased ...
In some invertebrates, glutamate is the main excitatory transmitter at the neuromuscular junction. [3] [4] In the neuromuscular junction of vertebrates, EPP (end-plate potentials) are mediated by the neurotransmitter acetylcholine, which (along with glutamate) is one of the primary transmitters in the central nervous system of invertebrates. [5]