Most of the time, the skeletal muscles are under voluntary, or conscious, control. However, their movement can also be induced by involuntary reflexes. Reflexes are involuntary reactions to a stimulus. In this example, the sensation of hot oatmeal on the skin causes this man’s hand to quickly withdraw to prevent further injury.

Let’s look at an instant replay to see how this reflex response works.

As soon as the hot oatmeal contacts the hand, the pain receptors send a signal to the spinal cord. In turn, the spinal cord sends a signal back to the arm muscles that make him pull his hand away. Because the arm flexed as it withdrew, this reflex is really known as a flexor, or withdrawal, reflex. There are many other reflexes that protect the body as well.

If this man didn't have the reflexes to let him withdraw quickly from a painful stimulus, he would be at risk for serious injury.