Item no.: P4030211
Principle
Tapping the Achilles tendon stretches the calf muscle and causes a reflex contraction in the muscle. This happens because the spindles sense the stretch and send an action potential to the motor neurons which then cause the muscle to contract. The amplitude of the muscle action potential is higher with tensed arm musculature than with relaxed arm musculature (approx. 3 mV compared to approx. 2 mV). The cause of this so-called Jendrassik effect is that, as a result of the tensing of the arm musculature, the other motoneurons of the spinal cord are innervated (facilitation).
Tasks
- Trigger a stretch reflex in the lower leg musculature by tapping the Achilles tendon (Achilles tendon reflex)
- Record the compound action potential and determine the reflex latency and the conduction velocity.
What you can learn about
- Electromyogram
- Muscle stretch reflex
- Achilles tendon
- Reflex latency
- Conduction velocity
- Jendrassik effect
- Facilitation