I have been sharing a series of publications in which I am talking about the Nervous System from different points, trying to make the subject as pleasant and easy to understand as possible, considering that when talking about this system we are facing one of the most complex of the organism but at the same time the most intriguing.
Much has been discovered in recent years, thanks to the development and progress that has been made in the field of imaging studies and the increased ability to study nerve impulses, so in this third publication I would like to socialize a topic that I know can be very striking for people, because at some point they may have seen it, but do not understand the justification for this routine study, such as reflections.
Let's start by defining what a reflex arc is, as they are usually called:
"Can be defined as an involuntary, qualitatively invariable nervous system response to a stimulus."Source
The most interesting thing, in my opinion, is that this is involuntary, since the impulse does not reach the brain but the spinal cord, which causes an immediate reaction to the stimulus. We have all at some point, surely, gone through the fact that we hit our elbow and feel a "rush " in the whole arm that makes us move quickly and involuntarily the whole arm, I guess with this example everyone knows what I'm talking about.
To the right there is a very well known "Hammer " that has a rubber band on its end, it is the one indicated to perform the respective physical examination that evaluates the reflexes.
There are specific points of our body where very well known nerves pass, which are known to trigger this Reflex Arc when gently hit with this medical instrument.
The exploration of this part of the nervous system is fundamental in the physical examination of the patient, and can give us very important data on the functioning of the nervous system by assessing the response and the strength of this response (if any).
The question in this case, which is likely to be asked by many people is What does this test say?, for example, if a certain area is stimulated and the expected reflex does not appear What does it mean?. I will explain the purpose below.
As I recently explained in Part two of this series, when a stimulus is received, the signal is sent through the nerves to the spinal cord, which carries it to the brain where it is processed, sending a specific response, in which consciousness will often be involved, but in the case of the reflex arc it is different.
As you can see in the image above, once the rubber hammer makes contact with the knee (for the case of the example) the nerve is stimulated which immediately sends the signal to the spinal cord, from where an automatic response, a reaction, comes out, demonstrating that all that nerve pathway is undamaged, this is the main result in which this test makes us think about.
We cannot see the nervous system in a direct way, unless it is in full surgery, which is not usual, besides that to know how it is working there are many non-invasive tests nowadays, such as electromyography, which could define exactly if a nerve is transmitting the information in an adequate way.
This is when a basic study such as this one, with the use of the rubber hammer that I have shown previously, can give us an orientation regarding the functioning of a specific nerve. As you have been able to see, when the nerve receives the gentle blow it immediately emits the signal that returns quickly saying that "you have to move the affected limb ", if this reaction, this reflex arc does not occur, we can have an indication that there is a nerve injury somewhere along the nerve pathway.
I must say that at the level of expression the reflexes like the patellar (of the knee) are the ones that can be perceived more easily or the amplitude of its movement, but there are many others, like for example the corneal reflex, which is done with an Izopo or with a small piece of cotton, passing it gently through the eye, and what is expected is that the rapid closure of the eye occurs, that is the most logical response, but it could not occur, which in turn would speak to us of a lesion at the level of some of the nerves of the eye, including the palpebral (of the eyelids).
Conclusion
As you can see, it is a very used way to quickly assess the functioning of the nervous system in a patient, and that without many tools allows the doctor to know in a simple way more about an important organic system.
Thank you for reading the publication, any questions, doubts or suggestions will be welcome.
I invite you to read the first two parts of this series:
Understanding our nervous system - Part One
Understanding our nervous system - Part two
Links consulted
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