Which reflex corresponds to the L2-L4 nerve roots?

• A. Biceps (C5-6)
• B. Triceps (C7-8)
• C. Brachioradialis (C5-6)
• D. Patellar (L2-4)

Answer: (D)

The knee-jerk (patellar) reflex is the one tied to L2-L4. When the patellar tendon is tapped, the quadriceps muscle is stretched, and muscle spindles send signals to the spinal cord via the femoral nerve. The L2-L4 motor neurons respond by triggering quadriceps contraction, producing knee extension. This reflex arc specifically tests the L2-L4 level.

For context, the biceps reflex involves C5-6, the brachioradialis also involves C5-6, and the triceps reflex tests C7-8. So the reflex corresponding to L2-L4 is the patellar reflex.