What is the muscle involved in ankle jerk flex?

The muscle involved in the ankle jerk reflex, also known as the Achilles reflex, is the gastrocnemius muscle, along with the soleus muscle, which collectively make up the calf muscles. When the Achilles tendon is tapped, these muscles contract, causing the foot to point downward. This reflex is mediated by the S1 and S2 spinal nerves.