What is Ankle jerk (Achilles)?

Ankle jerk (Achilles) is when your foot suddenly moves because of a special signal from your brain.

Imagine you're playing with your favorite toy car on the floor. You sit still, and then, BOOM!, your foot flicks upward as if it was pushed by an invisible friend. That’s what happens during an ankle jerk: your brain sends a quick message to your leg muscles through a nerve, telling them to move. The nerve involved is called the Achilles nerve because it’s connected to your Achilles tendon, the strong band of tissue at the back of your heel that helps you jump and run.

Your brain is like a boss giving orders. When the boss says, “Jump!” your foot moves. In an ankle jerk test, doctors or nurses tap your Achilles tendon with a little hammer, which acts like a boss shouting, “Move now!” The nerve sends the message up to your brain and back down to your leg in a flash, that’s why your foot jerks!

It's like when you're waiting for your turn on the swing. Just as you're about to push off, someone gives you a little nudge, and WHOOSH! You’re swinging higher than ever!