August 29, 2016
font size

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.

Source: MedTerms™ Medical Dictionary
Last Editorial Review: 5/13/2016

Drug Medical Dictionary of Terms by Letter

Top RxList Drug News

WebMD Daily

Get breaking medical news.

Use Pill Finder Find it Now See Interactions

Pill Identifier on RxList

  • quick, easy,
    pill identification

Find a Local Pharmacy

  • including 24 hour, pharmacies

Interaction Checker

  • Check potential drug interactions
Search the Medical Dictionary for Health Definitions & Medical Abbreviations