Lower Extremity of Radius - Non-articular Surfaces

Non-articular Surfaces

This end of the bone has three non-articular surfaces - volar, dorsal, and lateral.

• The volar surface, rough and irregular, affords attachment to the volar radiocarpal ligament.

• The dorsal surface is convex, affords attachment to the dorsal radiocarpal ligament, and is marked by three grooves. Enumerated from the lateral side:
  • The first groove is broad, but shallow, and subdivided into two by a slight ridge; the lateral of these two transmits the tendon of the extensor carpi radialis longus muscle, the medial the tendon of the extensor carpi radialis brevis muscle.
  • The second is deep but narrow, and bounded laterally by a sharply defined ridge; it is directed obliquely from above downward and lateralward, and transmits the tendon of the extensor pollicis longus muscle.
  • The third is broad, for the passage of the tendons of the Extensor indicis proprius and Extensor digitorum communis.

• The lateral surface is prolonged obliquely downward into a strong, conical projection, the styloid process, which gives attachment by its base to the tendon of the brachioradialis, and by its apex to the radial collateral ligament of the wrist joint. The lateral surface of this process is marked by a flat groove, for the tendons of the abductor pollicis longus muscle and extensor pollicis brevis muscle.