Definition of Knee jerk

Knee jerk: The reflex that is tested by tapping just below the bent knee on the patellar tendon. Normally this causes the quadriceps muscle to contract and bring the lower leg forward. It has given rise to the saying 'a knee-jerk reaction.' Also known as patellar reflex.


Last Editorial Review: 3/19/2012

Search MedTerms:


Back to MedTerms online medical dictionary A-Z List
Pill Identifier Tool

Need help identifying pills and medications?
Use the pill finder tool on RxList.


STAY INFORMED

Get the Latest health and medical information delivered direct to your inbox!