Stop Hitting Me! A Brief Look At Reflexes
Have you ever wondered why we tap your knees to make you kick? đ¤ Weâre testing your reflexes!
Pictured are three different types of reflex hammers. Youâre probably most familiar with the one on the right. We use them to test your deep tendon reflexes (aka stretch reflexes). The one youâre likely familiar with is where we tap your knee (specifically your patellar tendon) while itâs relaxed, causing your leg to kick.
Whatâs interesting is that this all happens without any input from the brain! After tapping your knee, a signal travels up your leg to the spinal cord about as high as your lower back and then is transferred directly back down to the quad muscles causing a kick. That specific signal never makes its way to the brain; thatâs why itâs called a reflex. Your leg kicked on autopilot without your brain telling it to. Thatâs part of the reason why reflexes are so fast!
So why do we check this? Well, itâs not all just for fun. đ There are some problems that can alter your bodyâs reflexes. Testing them can not only help us identify potential problems, but can also help us identify where the problem is located…
Firstly, the âknee reflexâ is only one of many reflexes we can tap throughout your arms and legs. Each reflex correlates to a specific group of nerves and spinal level, so that helps us pinpoint an area in your body.
Secondly, the intensity of your reflex is telling as well. If you have little or no reflex (response to the tap) that can indicate the problem likely involves whatâs called a lower motor neuron. But if I tap your knee and you nearly kick me in my face that typically indicates the problem involves something called an upper motor neuron.
Therefore, itâs important to try and relax and certainly donât make yourself kick just because you know thatâs what weâre looking for. (We can tell when you fake it, BTW. đ) And donât get worried if you feel like your reflexes are weak, absent, or really strong because some people naturally have those too and it doesnât always means that something is wrong. Your doctor/PA/NP will let you know if theyâre concerned about it. Or you can ask them if itâs worrying you!
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