@timsdeece I had these contractions too, and they were being caused by spinal cord compression in my neck. My C5/C6 was ruptured and bone spurs were growing into my spinal cord and those got worse in time until there was no space left around my spinal cord. It was the compression causing them, and having spine surgery made it stop. At one point, i could bend my neck and send an electric bolt down my entire body. I was trying to get surgical help, but couldn't find that until I came to Mayo.

A twitch response is caused by an electrical impulse, and when it is repeating, the muscle twitches every time there is an impulse. When impulses get fast enough, the contraction is sustained as tetany which can be a muscle spasm. This is an experiment we did in high school advanced biology lab by shocking a classmates leg and turning up the speed of the impulses to find the speed at which the contraction became sustained. Compression of a nerve does cause twitches as it did for me. I responded to your other post with information about entrapment of the lumbar plexus as a possible cause. I had a similar video of muscles jumping in my leg that I recorded when my doctors hadn't figured out the connection with my symptoms and my spine problem. Muscle contraction also depends on chemistry that moves ions across the muscle cell membranes as it propigates the conduction of the electrical impulse along the muscle fiber.