Biceps Reflex Test

Biceps reflex or C5 nerve root reflex is a deep tendon reflex test that evaluate the function of the C5 and C6 reflex arcs.

How to perform the Biceps Reflex?

The patient is position in sitting looking away from the tested side, while the examiner stands to the side of the patient, cradling the forearm with the thumb placed over the tendon. With the arm relaxed and the forearm slightly pronated and midway between flexion and extension, the examiner places the palmar surface of her extended thumb or finger on the patient’s biceps tendon and then strikes the extensor surface with the reflex hammer.

Pressure on the tendon should be light; too much pressure exerted with the thumb or finger against the tendon makes the reflex much harder to obtain. The hands may lie in the patient’s lap, or the examiner may hold the patient’s arm with the elbow resting in her hand. The major response is a contraction of the biceps muscle with flexion of the elbow.

Because the biceps muscle is also a supinator, there is often a certain amount of supination. If the biceps reflex is exaggerated, the reflexogenic zone is increased and the reflex may even be obtained by tapping the clavicle; there may be abnormal spread with accompanying flexion of the wrist and fingers and adduction of the thumb.

See Also: Deep Tendon Reflex Testing

The outcome of the Biceps Reflex Test can vary based on the individual’s reflex response:

• Normal Response: A mild contraction of the biceps muscle and a slight elbow flexion. This is a sign that the C5 and C6 nerve roots are functioning normally.
• Hyperreflexia (Exaggerated Response): An overly strong reflex may suggest central nervous system involvement, such as upper motor neuron lesions. Conditions like multiple sclerosis or a stroke might present with hyperreflexia.
• Hyporeflexia or Areflexia (Diminished or Absent Response): Weak or absent reflexes can indicate peripheral nerve damage or lower motor neuron issues. Possible causes include radiculopathy, peripheral neuropathy, or neuromuscular junction disorders.

References & More

1. Walker HK. Deep Tendon Reflexes. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 72. Available from: Pubmed
2. DeJong’s The Neurologic Examination – 8th Edition