Anterior Wrist

Articular Surfaces

Posterior Wrist

Radiocarpal Ligaments

Wrist Joint

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Anterior Wrist

The carpal tunnel is formed by the concave surface that results from the interaction of the carpal bones and is bridged by the flexor retinaculum, the thickened distal fibers of the deep antebrachial fascia. Most of the tendons of finger and wrist flexor muscles (the flexor carpi radialis and flexor digitorum profundus muscles are identified in this picture) run through this tunnel. The other important structure that is found here is the median nerve. The carpal tunnel is a narrow space with many structures passing through it. Because of the proximity of these tendons to the median nerve, it is easy to see how this nerve is compromised in people suffering from carpal tunnel syndrome.

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Posterior Wrist

The extensor retinaculum is an important structure on the posterior surface of the wrist. All of the tendons that function to extend the wrist or fingers (the tendons of the extensor digitorum communis muscle are clearly seen in this picture) run under this tough band. It is important biomechanically in that it prevents "bowstringing" of the extensor tendons, which would effectively decrease the ability of these muscles to produce the desired action.

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Radiocarpal Ligaments

This image shows the palmar radiocarpal ligaments. They run in an oblique direction from the distal radius to various carpal bones. It is an important anterior stabilizer of the articular joint capsule. It helps prevent excessive anterior dislocation of the carpal bones. The pronator quadratus muscle is also visible in this image. It is the main pronator of the radioulnar joints. It is the deepest muscle of the forearm and, therefore, cannot be palpated.

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Articular Surfaces

This image demonstrates the concave surface of the distal radius and the articular disc as they would interact with the convex surface formed by the scaphoid and lunate bones of the proximal row of carpals. It is important to remember that the ulna plays no true part in the formation of this joint. Note the ulnar collateral and radial collateral ligaments on each side of the joint. These ligaments provide medial and lateral stability to the joint as well as strengthening the articular joint capsule on their respective side.

In this image the wrist is flexed. This allows a better view of the posterior articular surface of the lunate and scaphoid bones with the ulna and radius.

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Wrist Joint

When speaking of the wrist joint, individuals are usually referring to the radiocarpal joint between the distal radius and the proximal row of carpals, mainly the scaphoid and lunate bones. It is a synovial joint that allows flexion, extension, abduction (radial deviation), and adduction (ulnar deviation). From this image you can also view the other bones from the proximal row of carpals, the pisiform and triquetrum. The pisiform is nothing more than a sesamoid bone that lies in the tendon of the flexor carpi ulnaris muscle. Also note that the triquetrum is not involved in the wrist joint.