What Is a Fibrous Joint?

The neuromuscular junction is the contact point of the axonal tip of the motor neuron on the skeletal muscle fiber. Motor neurons located in the anterior horn of the spinal cord and in some of the nucleus of the brainstem send out a long axon, the nerve fiber, to each of the muscles under their control. These nerve fibers are divided into dozens or more branches near the muscle cells, that is, the muscle fibers. A branch usually terminates on only one muscle fiber, forming a one-to-one neuromuscular junction. The signal from the nerve fiber is transmitted to the muscle fiber through the joint, causing the muscle to contract. In addition, the other role of the neuromuscular junction is that its presence can maintain a certain degree of muscle tension and inhibit muscle atrophy; if this connection is broken, then muscle atrophy will occur. ^{[1] The} neuromuscular junction is a specialized chemical synapse whose transmitter is acetylcholine (ACh). The neurotransmitter of invertebrates such as crawfish is glutamate (transmitter of excitatory fibers) or -aminobutyric acid (transmitter of inhibitory fibers).

Neuromuscular junction

motion

Excitatory transmission at the neuromuscular junction

under normal circumstances

There has been a long debate about whether neuromuscular junction transmission is electrical or chemical. Austrian scientist O. Levy first demonstrated experimentally the synaptic chemical transmission theory on frog heart perfusion specimens, and applied this theory to neuromuscular junctions by British scientist HH Dale et al. (1936 year). But it was not until the early 1950s that microelectrode technology was applied to the joint research, and its chemical transfer theory was finally established.