gastrocnemius reflex

ankle reflex

An abrupt plantar jerk of the ankle, evoked by tapping the Achilles tendon with an unrestricted forefoot.

Method
Slightly externally rotate at the hip and gently dorsiflex the foot, tapping the Achilles tendon with a reflex hammer; there should be a reflex contraction of the gastrocnemius muscle (plantar flexion).

gastrocnemius reflex

a spinal reflex, elicited by tapping the gastrocnemius tendon. A normal response is extension of the hock. Depressed by lesions in the spinal cord from L6 to S2 and of the sciatic and peroneal nerves; increased in spinal cord lesions above L6.