Achilles tendon reflex

In which Achilles reflex or Triceps surea reflex it is a reflex. It belongs to the group of so-called self-reflexes and describes the body's reaction to a blow on the Achilles tendon. After this blow, stimuli are passed on in the body, which leads to the ankle being stretched.

What is the Achilles reflex?

The Achilles tendon or Tendo musculi tricipitis sureae is the strongest tendon in the human body and connects the calf muscles, which are also known as the triceps surea muscles, with the heel.

These calf muscles consist of three muscle groups, the two calf muscles (gastrocnemius muscle) and the clod muscle or soleus muscle. The length of this tendon is about 20 to 25 cm. The calf muscles are controlled by the Achilles tendon. In this way, movements such as pulling the foot in, similar to a ballerina when she stands on tiptoe, or twisting the foot outwards, can be generated.

The Achilles tendon reflex is triggered by a light tap on the Achilles tendon. A stimulus signal is passed on via afferent nerve fibers. Afferent nerve fibers are those nerve fibers that transmit incoming signals, in this case the blow to the Achilles' eyes, which occurred from outside, to the respective destination in the body.

In this case, the afferent nerve is the tibial nerve. He conducts the signal to the spinal cord. There the incoming signal is passed on to the efferent nerve fibers. These nerve fibers transmit the signal to the outside. In the case of the Achilles tendon reflex, this also happens through the tibial nerve. The incoming signal from the efferent nerve fibers creates a contraction of the triceps aurea muscle, i.e. the calf muscles. This will stretch the ankle. This whole process is also described as a reflex arc.

Function & task

The Achilles tendon reflex is just one of several reflexes in the human body. It belongs to the group of self-reflexes and is often used to protect the body from damage. The self-reflex is a reflex in which a reaction of the organ in question to a stimulus is resolved, which means that the reaction takes place exactly where the stimulus arrived. In the case of external reflexes, the reaction takes place at a different location than that of the stimulus input.

A stimulus is sent from afferent nerve fibers to the spinal cord and then returned via efferent nerve fibers and the affected muscle to trigger a response from the muscle. In addition to the Achilles tendon reflex, there are a few others, such as the abdominal skin reflex. If the abdominal wall is hit, the abdominal wall contracts immediately, causing the abdominal wall to harden. This protects the internal organs from damage caused by external blows.

Another reflex is the toe flexion reflex. This is also known as the Rossolimo reflex and describes the reaction to a blow on the toe berries. In response, the toes are flexed. This reflex is usually only present in newborns and provides information about a possible disease of the nervous system or the motor system.

A well-known self-reflex is the adductor reflex. This is a reflex triggered by the blow on the adductor tendons on the knee joint. The affected leg kicks out. The reflexes are supposed to protect certain areas such as the internal organs of humans, but also, for example, from hot or sharp objects or from falling, which could cause damage.

Illnesses & ailments

Another reason for a defective reflex arc is damage to the spinal cord or the nerve fibers that transmit the signals. The Achilles tendon reflex arch is passed on by afferent nerve fibers over the spinal cord and the efferent nerve fibers. These then pass the signal on to the calf muscle. If this signal transmission is disturbed, this may be due to insufficient signal transmission, i.e. defects in nerve fibers or in the spinal cord. As a result, the signal may not be able to travel from the afferent nerve fibers to the efferent nerve fibers through the spinal cord.

Damage to the spinal cord can have various reasons. A trauma to the spinal cord is possible, i.e. damage to the spinal cord as a result of violence, such as in a car accident.

In addition, a defective Achilles tendon reflex can also indicate a herniated disc, in which the intervertebral discs between the vertebrae are damaged and lose their dampening effect.

A defective Achilles tendon reflex can also indicate polio, which is also known as polio. Polio is caused by the poliovirus and causes paralysis by infecting nerve cells and the spinal cord.

In addition, a non-functioning Achilles tendon reflex can also indicate neurosyphilis. This is damage to the nerves caused by an unhealed syphilis disease. This disease was common in the 18th century, but is no longer common today.