What is a Reflex?

Most of us have had the experience where we are sitting on an examination table at the doctor’s office and the doctor uses a funny looking rubber hammer to hit our knee. Followed by, that well-known and almost comical response of kicking our legs out. I’ve noticed, from a practitioner’s point of view, that this is one of the times where I get the biggest reactions from patients. The literal “knee-jerk” reaction sometimes is met with immediate laughs or other times it’s met with gasps of surprise. But jokes and funny feelings aside, why does a doctor do this? What are they even looking for? What is a reflex? Where we can use reflexes in treatment? Read more to find out.

What is a reflex?

Reflexes, by definition, are responses from our body that are involuntary as a direct reaction to a stimulus. In everyday terms they are actions in our bodies that happen without our control. Reflexes are present all over our bodies constantly aiding in things like the size of our pupils, “tightness” of our muscles, going to the bathroom, and even our blood pressure. Some reflexes should only be seen in babies.

Often-time’s reflexes exist when one nerve in our body detects something, and directly tells another nerve to do something. In the case of the knee, nerves that measure the tension of a muscle are being stimulated with the tap of the hammer. That nerve travels like a long wire up the leg to the spinal cord where it communicates to a different nerve. The second nerve travels back down the thigh and its function is to activate the very muscle that was stimulated in the beginning. The muscle twitches as a response to the increase in tension. If you’re still following with me, this is where it gets interesting.

The signal creates a response before it gets to our brain. This is why it can be so startling to get your reflexes tested. So in the simplest form, reflexes operate as a direct function of our nerves ability to communicate. There are instances where reflexes in the body can increase, decrease, or even disappear. Applying anatomical knowledge of where the nerves travel, and what they control, doctors can use reflexes like a road map back to find where certain injuries are.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4540252
https://www.ncbi.nlm.nih.gov/books/NBK562238/

Why does a doctor test my Reflexes?

We’ll get further into the hammer tap or muscle stretch reflex, but I think the most familiar example is something that people wouldn’t realize is even testing for a reflex. You’ve probably seen on a medical drama, or maybe an EMT in real life who shines a flashlight in someone’s eyes. This is an instance of testing a reflex. Nerves in our eye that detect light communicate with nerves that control our iris, and change the size of our pupils. Since these nerves that control our eyes are cranial nerves, it can be a great screening tool in head traumas.

In the sense of a chiropractic evaluation it is very important to assess the communication of nerves that exit from our spine. Often times if I suspect that a patient may have a “pinched nerve”, in the neck or the back, testing reflexes in the arms and legs is prudent and this is where the hammer comes in. Because the nerves involved in the muscle reflexes communicate in our spinal cord, testing reflexes of different muscles can give a road-map back to exactly where the issue is at. When a reflex in the knee is diminished, it could be evidence that the nerves in their lower back are not functioning properly.

Finally testing reflexes can be a good indicator for overall health. There are conditions that decrease our reflexes overall such as diabetes, peripheral neuropathy, and Guillain-Barre Syndrome. There are also conditions that can increase our reflexes. Disorders of the spinal cord such as multiple sclerosis, cerebral palsy, and strokes can increase our reflexes.

https://www.ncbi.nlm.nih.gov/books/NBK553169/
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Motor-Neuron-Diseases-Fact-Sheet
https://www.ncbi.nlm.nih.gov/books/NBK539814/

Reflexes in treatment

While the simple explanation of the muscle stretch reflex is that when a muscle is stretched, reflexively our body contracts that muscle, there is also a reflex that results in muscle relaxation. In our body, wehave little sensors called Golgi Tendon Organs (GTO’s) which can detect how much tension is on the muscle. In order to protect it, when the Golgi Tendon Organ is stimulated it reflexively causes muscle relaxation. This is a reflex that is activated during a chiropractic adjustment or spinal manipulation. This neurological response is so much greater than “putting bones back in place”. It uses our bodies own systems to make us feel better, and that’s pretty awesome!

https://pubmed.ncbi.nlm.nih.gov/31228207/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3399029/

Reflexes are fascinating

Reflexes comprise a fascinating aspect of our physiology. They are an excellent tool in the screening process for evaluating an injury, or assessing overall health. The strongest recommendation that I can give to anyone reading, is to make sure that you seek out a practitioner who thoroughly evaluates your specific condition. I encourage patients to ask their providers what the tests they are performing are looking for. Gravitate towards providers who can concisely explain why they are doing certain tests. Remember that healthcare is your right and your responsibility. Find a practitioner who will work with you in order to find the treatment that is best for you.