Brachioradialis Muscle

The brachioradialis, a fusiform muscle, lies superficially on the anterolateral surface of the forearm. It forms the lateral border of the cubital fossa.

The brachioradialis is exceptional among muscles of the posterior (extensor) compartment in that it has rotated to the anterior aspect of the humerus and thus flexes the forearm at the elbow. It is especially active during quick movements or in the presence of resistance during flexion of the forearm (e.g., when a weight is lifted), acting as a shunt muscle resisting subluxation of the head of the radius.

The brachioradialis and the supinator are the only muscles of the compartment that do not cross the wrist and therefore are incapable of acting at the wrist. As it descends, the brachioradialis overlies the radial nerve and artery where they lie together on the supinator, pronator teres tendon, FDS, and FPL. The distal part of the tendon is covered by the abductors pollicis longus and brevis as they pass to the thumb.

See Also: Forearm Muscles Anatomy & Function

Brachioradialis Muscle Anatomy

Origin

The Brachioradialis muscle arises from the proximal 2/3 of lateral supracondyle ridge of humerus.

Insertion

It rotates to the anterior aspect of the humerus, crossing the elbow joint and inserts on the lateral surface of distal end of radius.

Innervation

It’s innervated by the radial nerve (C5, C6, C7).

Blood Supply

Blood supply to the Brachioradialis muscle comes from the radial recurrent artery.

Action

Functionally, the brachioradialis is a flexor of the forearm, but it is located in the posterior (posterolateral) or extensor compartment and is thus supplied by the radial nerve. Therefore, the brachioradialis is a major exception to the rule that the radial nerve supplies only extensor muscles and that all flexors lie in the anterior (flexor) compartment.

The brachioradialis is an important muscle in the volar approach to the radius (Henry approach), where the surgeon must take care not to damage the superficial radial nerve that runs along the undersurface of the brachioradialis.

To test the brachioradialis, the elbow joint is flexed against resistance with the forearm in the midprone position. If the brachioradialis is acting normally, the muscle can be seen and palpated.

References & More

1. Clinically Oriented Anatomy – 8th Edition
2. Lung BE, Ekblad J, Bisogno M. Anatomy, Shoulder and Upper Limb, Forearm Brachioradialis Muscle. [Updated 2023 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526110/