Ankle jerk reflex

The Achilles tendon reflex ( ASR, also Triceps surae reflex) is a reflex, which belongs to the group of reflexes.

The reflex is triggered by a light tap on the Achilles tendon. The afferent limb of the reflex arc is the tibial nerve, which passes the stimulus to the spinal cord, more precisely to its cross section ( sacral section, S1 and S2). Here is switched over to the efferent limb, which also triggers a reflex contraction of the triceps surae muscle on the tibial nerve. This results in an extension of the ankle joint ( plantarflexion of the foot).

In case of malfunction of the thyroid gland of this reflex is particularly lively triggered and can provide a diagnostic indication here. Severe damage to the spinal cord can broaden the reflex triggering zone.

The absence of the reflex is an indication of damage to the anterior cruciate area of the spinal cord, such as occur for example in a trauma, the polio and neurosyphilis. Furthermore, a lack of Achilles tendon reflex occur with lesions of the corresponding nerve roots, for example as a result of a herniated disc.

• Proprioceptive reflex
• Spinal cord