Muscle stretch reflex

The muscle stretch reflex is a quick, automatic response that helps muscles maintain their length and tension. When a muscle is stretched suddenly—for example, tapping the knee with a reflex hammer—special sensory receptors in the muscle called muscle spindles detect the stretch. This information is sent to the spinal cord, which instantly sends a message back to the same muscle to contract. This reflex helps protect muscles from overstretching and maintains muscle tone, allowing your body to respond rapidly to sudden movements or changes in position without needing conscious effort.