Brachioradialis muscle

The brachioradialis muscle serves as an important elbow flexor and a key anatomical landmark.

Origin and Insertion

This muscle originates from the proximal two-thirds of the lateral supracondylar ridge of the humerus. It then extends distally to insert onto the lateral surface of the distal radius, just above the styloid process.

Innervation

The radial nerve innervates the brachioradialis muscle. This specific branch typically arises before the radial nerve divides into its superficial and deep branches distal to the elbow. Notably, the superficial branch of the radial nerve runs deep to the brachioradialis throughout the forearm, positioned lateral to the radial artery. It then emerges superficially between the tendons of the brachioradialis and extensor carpi radialis longus in the distal forearm.

Action

Functionally, the brachioradialis primarily acts as an elbow flexor, especially effective when the forearm is in a neutral (thumb-up) position. It also helps stabilize the forearm during elbow flexion. Interestingly, the muscle can both pronate the forearm when it's supinated and supinate it when it's pronated, helping to bring the forearm back to a neutral position.

Relations

Anatomically, the brachioradialis muscle is found along the lateral (radial) aspect of the forearm and forms the lateral border of the cubital fossa. Although it receives innervation from the radial nerve, it's not considered a true extensor compartment muscle. Its unique position and actions set it apart functionally from the posterior compartment extensors, which are supplied by the posterior interosseous nerve.