Brachioradialis

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Brachioradialis is a muscle of the forearm that acts primarily in the flexion of the elbow joint. It is unique among the muscles in the forearm in that it is a flexor that is located in the posterior compartment. The brachioradialis is a superficial muscle that extends from the lower part of the humerus to the distal radius of the forearm. Its primary function is to flex the forearm at the elbow, especially when the forearm is in a mid-position between pronation and supination.

Anatomy

The brachioradialis originates on the lateral supracondylar ridge of the humerus, just above the lateral epicondyle, and inserts on the lateral surface of the radius, near the styloid process. Unlike other muscles in the posterior compartment of the forearm, which are primarily involved in extension, the brachioradialis is a flexor. It is innervated by the radial nerve, specifically the C5-C6 spinal nerve roots.

The muscle is easily visible under the skin of the forearm, especially when the forearm is flexed. It acts as a stabilizer for the elbow during rapid flexion and extension movements.

Function

The primary function of the brachioradialis is to flex the forearm at the elbow. It is most effective when the forearm is in a neutral position, midway between pronation and supination. The muscle can also assist in the pronation and supination of the forearm when these movements are resisted.

In addition to its role in forearm flexion, the brachioradialis helps to stabilize the elbow joint during various activities, providing a balance between the forces produced by the flexor and extensor muscles.

Clinical Significance

Injury to the brachioradialis can result from overuse, strain, or direct trauma. Symptoms of injury may include pain, swelling, and weakness in the forearm, particularly during movements that involve flexing the elbow. Treatment typically involves rest, ice, compression, and elevation (RICE), along with physical therapy to restore strength and flexibility.

The brachioradialis reflex is a clinical test used to assess the integrity of the radial nerve and the C5-C6 spinal nerve roots. This reflex is elicited by striking the brachioradialis tendon directly with a reflex hammer, which should cause a quick flexion of the forearm at the elbow.

See Also

• Muscular system
• Forearm
• Elbow
• Radial nerve