When a physician taps the patellar tendon with a hammer, it causes a knee jerk reflex by sending stretch signals to:
A)motor neurons in the spinal cord that cause muscles to contract.
B)motor neurons in the cortex that cause muscles to contract.
C)the thalamus, which sends signals to motor neurons to contract.
D)the cerebellum, which sends signals to motor neurons to contract.

Question

Quizplus · Accepted Answer

The knee jerk reflex is a simple spinal reflex that involves sensory neurons sending signals to the spinal cord, which then directly communicate with motor neurons to cause muscle contraction, bypassing the brain.

When a Physician Taps the Patellar Tendon with a Hammer