Asked by: Olivia Mack, Newick

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That random little twitch that you sometimes get in your eyelid is an example of fasciculation. It happens when one of the lower motor neurons in your spine spontaneously fires a signal. These nerves control an entire block of muscle fibres, so they all contract at once. Because it’s benign, there hasn’t been much research into the causes, but magnesium deficiency is thought to be one factor.


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luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.

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