patellar reflex, a deep tendon reflex, elicited by a sharp tap on the tendon just distal to the patella, normally characterized by contraction of the quadriceps muscle and extension of the leg at the knee. The reflex is hyperactive in disease of the pyramidal tract above the level of the second lumbar vertebra. Also called knee-jerk reflex, quadriceps reflex. See also deep tendon reflex.
