Brachioradialis Reflex Test

The brachioradialis reflex or C6 Nerve Root Reflex is a deep tendon reflex involving the C5 and C6 nerve roots through its innervation by the radial nerve.

How to perform the Brachioradialis Reflex Test?

Tapping just above the styloid process of the radius with the forearm in semiflexion and semipronation causes flexion of the elbow, with variable supination. The supination is more marked with the forearm extended and pronated, but there is less flexion.

The tendon can be percussed not only at its insertion on the lateral aspect of the base of the styloid process of the radius but also at about the junction of the middle and distal thirds of the forearm or at its tendon of origin above the lateral epicondyle of the humerus.

See Also: Deep Tendon Reflex

The most common error is hitting the muscle belly rather than the tendon. The muscle becomes tendinous at about midforearm. A local contraction can be elicited from any muscle by directly striking the muscle belly. The point in eliciting a deep tendon reflex is to lengthen the muscle by stretching its tendon. An idiomuscular contraction can be obtained by striking the brachioradialis muscle belly in the proximal third of the forearm; this is not a deep tendon reflex.

If the reflex is exaggerated, there is associated flexion of the wrist and fingers, with adduction of the forearm. When the afferent limb of the reflex is impaired, there may be a twitch of the flexors of the hand and fingers without flexion and supination of the elbow; this is termed inversion of the reflex.

See Also: Brachioradialis Muscle Anatomy

References & More

1. Cao T, Tadi P. Brachioradialis Reflex. [Updated 2023 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed
2. DeJong’s The Neurologic Examination – 8th Edition