räpäytysrefleksi

Räpäytysrefleksi, also known as the knee-jerk reflex, is a rapid, involuntary contraction of the quadriceps muscle in response to a stimulus applied to the patellar tendon. This reflex is mediated by the stretch reflex arc, a neural pathway that includes sensory receptors, motor neurons, and interneurons. The sensory receptors are located in the muscle spindle, which detects changes in muscle length. When the patellar tendon is tapped, the muscle spindle is stretched, sending an impulse to the spinal cord. This impulse is then transmitted to the motor neurons, which innervate the quadriceps muscle, causing it to contract rapidly. The purpose of the räpäytysrefleksi is to maintain muscle tone and posture by providing immediate feedback to the central nervous system. It is commonly tested in clinical settings using a reflex hammer, and abnormal results can indicate various neurological conditions. The räpäytysrefleksi is an essential component of the body's reflex system, ensuring smooth and coordinated movement.