The ankle reflex, also known as the Achilles tendon reflex, is a deep tendon reflex tested to assess the function of the S1 nerve root (and to some extent, S2). Here's how to perform it:
Steps to Elicit the Ankle Reflex
- Patient Positioning: Have the patient sit with their legs dangling freely or lie down with one leg flexed at the knee and externally rotated. Dorsiflex the foot at the ankle.
- Tendon Identification: Locate the Achilles tendon, which runs from the calf muscle to the heel.
- Tapping: Use a reflex hammer to sharply tap the Achilles tendon.
- Observation: Observe for plantar flexion of the foot (the foot moves downwards). This indicates a normal ankle reflex.
- Repeat: Flex the foot and perform the tap again to ensure the reflex is accurate.
The presence of plantar flexion after tapping the Achilles tendon indicates an intact reflex arc. Absence or diminution of the reflex can suggest neurological issues.
