The Wrist (Radio-Carpal) Joint between the distal end of the radius and the triangular fibro-cartilage, and the proximal row of carpal bones.

The joint is a condyloid one, capable of movement through two axes:

Antero-posterior - flexion and extension.

Transverse - abduction and adduction.

In the ordinary position of the hand the end of the radius and articular disc are in contact with the scaphoid and semilunar bones, but in adduction (the hand bent to the ulnar side) the cuneiform bone is pushed outward and comes in contact with the triangular fibro-cartilage instead of the capsule of the joint.

Ligaments

A capsule completely surrounds the joint, and is attached to the edges of the articular surfaces, and is carried up to the edge of the lower end and styloid process of the ulna. It has well-defined strengthened portions.

Anterior Carpal ligament, attached above, to the lower edge of the radius, the styloid process of the ulna, and the anterior border of the triangular fibro-cartilage; below, to the palmar surfaces of the scaphoid, semilunar, and cuneiform bones. Some fibres may be carried on to the os magnum.

Posterior-carpal ligament, attached above to the lower end of the radius and below to the dorsal surfaces of the proximal row of bones.

Fig. 9. - Muscles of the Forearm (Dorsal Aspect).

Internal Lateral ligament, attached above to the styloid process of the ulna, and below to the ulnar side of the cuneiform and pisiform bones.

External Lateral ligament, attached above to the styloid process of the radius, and below to the tubercle of the scaphoid.

The synovial membrane completely lines the joint cavity, and may be continuous with that of the inferior radio-ulnar joint if the articular disc be perforated.