Flexor Carpi Radialis

Origin

The flexor carpi radialis muscle originates from the:

- medial epicondyle of humerus, via the common flexor tendon;

- adjacent antebrachial fascia.

The common flexor tendon is the combined tendon for all five superficial muscles in the anterior compartment of the forearm, which are the:

- pronator teres muscle;

- flexor carpi radialis muscle;

- palmaris longus muscle;

- flexor carpi ulnaris muscle;

- flexor digitorum superficialis muscle.

Insertion

The fibers of the flexor carpi radialis muscle travel inferiorly to the hand and insert, via a long tendon, onto the palmar aspects of the bases of the second and third metacarpal bones.

Key Features & Anatomical Relations

The flexor carpi radialis muscle is one of the muscles of the superficial part of anterior compartment of the forearm. It is a fusiform type of skeletal muscle.

In the middle of the forearm, the muscle belly gives rise to a long tendon, which travels inferolaterally. At the wrist, the tendon travels deep to the flexor retinaculum of hand, where it passes through the tendinous sheath of flexor carpi radialis. The tendon then travels to the palm of the hand and to its insertion sites.

The flexor carpi radialis muscle is located:

- anterior (superficial) to the flexor digitorum superficialis muscle;

- medial to the pronator teres muscle (at its muscle belly) and the radial artery (at its distal tendon);

- lateral to the palmaris longus muscle (at its muscle belly) and the median nerve (at its distal tendon).

Actions & Testing

The flexor carpi radialis muscle is involved in multiple actions:

- flexes the hand at the radiocarpal (wrist) joint, which occurs when the flexor carpi ulnaris muscle contracts simultaneously with it;

- abducts the hand at the radiocarpal and midcarpal joints, which occurs when the extensor carpi radialis longus and brevis muscles contract simultaneously with it.

The flexor carpi radialis muscle can be tested by flexing the hand at the radiocarpal joint against resistance, during which its tendon can be palpated (Standring, 2016).

List of Clinical Correlates

- Medial epicondylitis (golfer’s elbow)

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.