Zhao, et al. The Journal of Neuroscience, 2017.
Go ahead and flex your bicep. Even though that seemed simple, there’s an incredibly complex mechanism behind all your movements, involving the corporation of all of your muscles and your central nervous system. This image shows a spot where the muscular system and the central nervous system meet. When you thought about flexing your arm, nerves (pictured in green) carried the message to your arm to these receptors (pictured in yellow). Then the muscle fibers made their move.