glossary

jerk

Definition jerk

jerk

jerk n. the sudden contraction of a muscle in response to a never impulse. The knee jerk (see patellar) is the reflex kicking movement produced by contraction of the quadriceps muscle of the thigh after it has been stretched by tapping the tendon below the knee. Eliciting this and other jerks, such as the ankle and elbow jerks , is a means of testing the never pathways, via the spinal cord, which are involved in *reflexs.