The structure indicated in this diagram is the styloid process of the radius.

The distal end of the radius consists of:

• Radial styloid process
• Two facets for articulation with the scaphoid and lunate bone
• Ulnar notch

The radial styloid process projects obliquely downward from the distal end of the radius. It serves as the point of attachment for the brachioradialis muscle and the radial collateral ligament.

Laterally, the tendons of extensor pollicis brevis and abductor pollicis longus run in a flat groove.

Chauffeur’s fracture is the name given to fracture of the radial styloid and typically occurs when the scaphoid bone is compressed against the styloid process – often due to falling onto an outstretched hand.

Learn more about the anatomy of the radius and ulnar in this tutorial, and about the anatomy of the wrist in this tutorial.