How does the reflex beneath the knee cap make your leg “swing” when you hit it?

Question

How does the reflex beneath the knee cap make your leg “swing” when you hit it?

In: 136

Answer 1

The sensory nerve terminating at the knee runs all the way up the leg to the spinal cord, synapses with the motor nerve there, and then the motor nerve runs back down the leg to trigger the muscle. So the reason the reflex test is useful is that it shows how well your nerves are conducting over a relatively large distance.