We went to the consultation with our back or neck pain. We have told our doctor our problem and then the physical exam begins. During the exploration the doctor takes out a hammer and hits us in some areas of the body to remove the reflexes. What is the doctor doing? What is this for?
What are reflexes?
The hammer is used to evaluate the reflexes. To understand the information that can bring us we must understand what a reflection is. We are going to put an example. Imagine that we are cooking and unwittingly lean one finger on the frying pan. Automatically we withdraw our hand when we feel the burning.
Let’s analyze what has happened. Normally if we want to move the arm, in a part of our brain we generate the idea and we send it to another part of the brain called motor cortex that will activate the signal. This signal travels through the brain, then through the marrow and finally, through the nerve root and nerve, reaches the muscle we want to move. In this way we think of moving the arm and finally moving it.
Returning to the example, one might think that by noting that the pan was hot decided to remove the hand and, as explained above, the signal sent from the brain to your arm to do it. This is not so because it is very slow and it would take too long to remove the hand from the fire. So, how does it work? We remove the hand quickly thanks to the reflexes, as we will see now.
The skin receptors detect the excess heat and the damage it is doing to the finger. These sensors send a signal traveling through the sensory nerve to the spinal cord that is in the column. The bone will interpret this damage and automatically sends the signal to the muscles that will remove the hand from the fire. This is called a reflex arc and is one of the functions of the spinal cord.
Why do we use a hammer for reflexes?
In the example we have mentioned, we are talking about removing the hand to avoid a burn but there are more types of reflexes. Let’s put more examples. If we are walking and we step on a stone, our foot twists and the position of the ankle changes abruptly. The sensors that are in the ligaments of the ankle joint detect this and activate a reflex arc to contract the muscles that stabilize the foot and ankle again. Without this reflex, instead of a sprain or a fright, we would have a severe ankle fracture.
There are other sensors that are in the tendons of the muscles and that activate the reflex arc when the tendon is stretched and it collaborates in the control of the contraction. This reflex is the one we use to perform part of the neurological study in the consultation. With the hammer we give a dry blow on the tendon and we cause the contraction of the muscle. It is a simple gesture that allows us to evaluate the nervous pathway described above.
If the reflex is normal we know that the receptor, the sensory nerve, the marrow and the motor nerve involved are healthy. But not only that. The reflex can be increased, diminished or even absent and each has its meaning. In addition, having two arms and two legs, we can compare one side to the other, which gives more value to the test.
The reflexes we can take in different tendons of the body as can be for example the elbow or the tendon of Achilles. Each reflex explores a different nervous pathway and the conclusions have a different sense as to the cause and location of the damage we are seeking.
In summary, we take reflexes with a hammer to help us explore the nerve pathways that come and go from the arms and legs to the spinal cord. In future posts I will explain the concrete meaning of each reflection that is explored in the arms and legs.
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