What type of reflex is tested by tapping below the kneecap?

The reflex tested by tapping below the kneecap is known as the patellar reflex. This is a classic example of a monosynaptic reflex arc, which involves a direct connection between the sensory and motor neurons. When the patellar tendon is tapped, it stretches the tendon as well as the quadriceps muscle just above the knee. This stretching stimulates sensory receptors called muscle spindles, sending a signal to the spinal cord.

In response, the spinal cord sends an immediate signal back through the motor neuron to the quadriceps muscle, causing it to contract. This contraction results in the leg kicking outward. The patellar reflex is commonly assessed during physical examinations because it helps evaluate the integrity of the nervous system, particularly the L2 to L4 segments of the spinal cord.

Understanding this reflex is important, as it serves as a fundamental component of neuromuscular function assessment in clinical practice.