noun, plural: Achilles reflexes
A stretch reflex wherein the foot jerks towards the plantar surface by reflex as a response to a tap on the Achilles tendon while the foot is dorsiflexed
A stretch reflex is a reflex reaction characterized by muscle contraction due to the stimulation of the muscle proprioceptors. When the muscle is stretched, the body reacts by resisting the stretch by reflex. Some of the stretch reflexes are jaw jerk reflex, biceps reflex, brachioradialis reflex, triceps reflex, patellar reflex, and ankle jerk reflex.
The Achilles reflex is a form of stretch reflex in which the foot jerks towards its plantar surface when the Achilles tendon is tapped while the foot is dorsiflexed. It is also applied in neurologic tests to examine the nerve status and the gastrocnemius muscle. The S1 spinal segment of the spinal cord controls this reflex. It is monosynaptic, meaning it involves only one synapse between the sensory neuron and the motor neuron. The test is done by tapping the Achilles tendon with a reflex hammer. A positive result is a brisk plantarflexion of the foot. The absence of or a slight Achilles reflex reaction may indicate a medical condition, e.g. lumbar herniated disk syndrome, hypothyroidism, sciatic neuropathy, hypothermia, etc.
- ankle jerk reflex