This reaction is a reflex: it was not a direct command. However, if a person's reflex pathway was or becomes disrupted in some way, they may not be able to transmit the information to the brain fast enough to avoid getting burned, or they may not even be able to sense heat until it's too late Furthermore, there are several reflex reactions that respond to instability, such as the knee instinct. The knee reflex is a sudden kicking movement made when something or someone sharply taps on the patellar tendon, which is located just below the kneecap. The touch causes a slight stretch of the quadriceps, which is the front part of the upper leg. This causes the muscles to contract in reaction and then straighten the leg through a kicking motion. The absence of the reaction indicates that the central nervous system may be damaged. Doctors also use the instinctive reflex to help recognize thyroid disease. The knee reflex, also known as the patellar reflex, is one of many forms of spinal reflex. A spinal reflex is thought to be important because of its automatic responses to stimuli that do not require thinking activity and is a form of protection