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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.
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]
The opposite can happen when the opening of ion channels results in the flow of negatively charged ions, like chloride (Cl −), into the cell, or positively charged ions, like potassium (K +), to flow out of the cell, creating inhibitory postsynaptic potentials (IPSP) that hyperpolarize the cell membrane, decreasing the likelihood of an action ...
A special case of a chemical synapse is the neuromuscular junction, in which the axon of a motor neuron terminates on a muscle fiber. [ae] In such cases, the released neurotransmitter is acetylcholine, which binds to the acetylcholine receptor, an integral membrane protein in the membrane (the sarcolemma) of the muscle fiber.
The time between a stimulus to the motor nerve and the subsequent contraction of the innervated muscle is called the latent period, which usually takes about 10 ms and is caused by the time taken for nerve action potential to propagate, the time for chemical transmission at the neuromuscular junction, then the subsequent steps in excitation ...
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.
In biology, a motor unit is made up of a motor neuron and all of the skeletal muscle fibers innervated by the neuron's axon terminals, including the neuromuscular junctions between the neuron and the fibres. [1] Groups of motor units often work together as a motor pool to coordinate the contractions of a single muscle.
Denervation studies at the neuromuscular junction of vertebrates have shown that the axon removal mechanism closely resembles Wallerian degeneration. [13] However, the global and simultaneous pruning seen in Drosophilia differs from the mammalian nervous system pruning, which occurs locally and over multiple stages of development. [6]