In this post I want to explain the reflexes that we evaluate when there is a cervical injury. To understand the osteotendinous reflexes that we take with a hammer in the consultation, I recommend going to the post of the link before continuing reading. Also the post in which I speak of the reflexes in the legs can help us to understand everything better. Between the cervical vertebrae come the nerve roots that will form the nerves that go by the arm. Through these nerves travels the signal that allows us to move the muscles of the upper limbs.
In cervical lesions, such as a hernia, we are concerned that there may be a nerve root injury. Taking reflexes helps us know how the nerve pathways are. Let’s look at the reflexes that we explored the doctors in the consultation:
– The bicipital reflex: To take this reflex we hit the anterior part of the elbow, in the flexor zone. When you hit, you will flex your elbow slightly. With this gesture we are evaluating the roots C5 and C6 that are involved in this reflex arc. It has more prominence C5 contrary to the following reflection that we are going to explain.
– The brachioradial reflex: This reflex will be achieved by tapping the long supinator muscle tendon on the lateral and distal side of the forearm. In other words, at the root of the big toe but higher up, above the wrist. When taking the reflex flexes the elbow, which is the main function of this muscle which is the long supinator. With this maneuver we will evaluate the roots C5 and C6 as with the anterior reflex but this time predominates C6.
– Tricipital reflex (initial image of the post): The triceps is a muscle that is in the back of the arm and is the one that is in charge of that we can extend the elbow, that is to say, to have the arm straight. The extension of the elbow is in favor of gravity so the arm posture needs to be changed to evaluate the reflex and see the elbow extension movement during the maneuver. When taking the tricipital reflex we are fundamentally evaluating the C7 root, although it has some C6 component.
The most important thing when interpreting the reflexes is perhaps the comparison with the other arm that is supposed to be healthy. We are going to put an example. If the reflex does not come out we can interpret that the pathway has been affected at some point and assume that there is a neurological injury. If we do not get the reflex on the healthy side, things change. Maybe we are not able to get it out for some reason (this happens) or that there is another reason, such as medication for example, that causes them not to go out.
It can also happen that a reflex looks normal and that when compared to the healthy side we notice that it is more muted than on the healthy side. This may indicate that we are facing an injury.
If the result of the maneuver is a reflex that is exalted, then the cause of the injury will probably no longer be in the nerve root and will be found in the upper pathways that regulate this response. The brain sends a series of nerve pathways to the marrow that have the function of regulating the intensity of motor responses. If these pathways are damaged, we may have an exalted reflex, greatly increased. In other words, hyperreflexia may be due to medullary or brain injury. We should not be frightened by this fact, with a single reflex we cannot draw these conclusions. They are suggestive data that must match the rest of the exploration and the tests that we have.
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