A patient has an abnormal right biceps deep tendon reflex. This finding localizes to which spinal segments?

A patient has an abnormal right biceps deep tendon reflex. This finding localizes to which spinal segments?

• A. Lumbar 2, 3, and 4
• B. Cervical 6 and 7
• C. Cervical 5 and 6
• D. Sacral 1

Answer: (C)

The biceps deep tendon reflex is driven mainly by the C5–C6 nerve roots. Its reflex arc begins with the muscle spindle in the biceps sending afferent signals into the spinal cord at C5–C6, and information then travels back out via the musculocutaneous nerve to elicit elbow flexion. So an abnormal biceps reflex localizes to the C5–C6 level. For context, other reflexes map to different segments: the triceps reflex tests C7–C8, the knee (patellar) reflex tests L4, and the ankle (Achilles) reflex tests S1.

The biceps deep tendon reflex is driven mainly by the C5–C6 nerve roots. Its reflex arc begins with the muscle spindle in the biceps sending afferent signals into the spinal cord at C5–C6, and information then travels back out via the musculocutaneous nerve to elicit elbow flexion. So an abnormal biceps reflex localizes to the C5–C6 level.

For context, other reflexes map to different segments: the triceps reflex tests C7–C8, the knee (patellar) reflex tests L4, and the ankle (Achilles) reflex tests S1.