Achilles Tendon

The Achilles Tendon reflex (also known as the ankle jerk reflex) is a reflexive reaction that occurs when the Achilles Tendon (the tendon that runs down he back of the leg and attaches to the heel) is tapped while the foot is dorsi-flexed (flexing your foot upward). The foot jerking towards the plantar surface (bottom of the foot or instep) is considered a positive result. This reflex tests the function of the gastrocnemius muscle and the nerve that supplies it.