The jerk made as a reflex action by the knee, when the legs are crossed and the patellar tendon is tapped sharply.
Deep tendon reflex in which tapping the tendon below the patella causes a contraction of the quadriceps muscle of the thigh and extension (kicking) of the lower leg; used diagnostically to test nerve function; also called knee-jerk reflex.
Striking the patellar ligaments resulting in extension of the lower leg.
The knee jerk, in which stretching the muscle at the front of the thigh by tapping its tendon below the knee cap causes a reflex contraction of the muscle, so that the leg kicks. This is a test of the connection between the sensory nerves attached to stretch receptors in the muscle, the spinal cord, and the motor neurons running from the cord to the thigh muscle, all of which are involved in the reflex. Disease or damage may result in absence of the reflex.
The reflexive movement of the lower leg triggered by striking just below the kneecap with a reflex hammer, often referred to as the knee jerk.