Ulna and Radius

Are two bones found in the forearm.

The radius is found on the side of the thumb.

The ulna on the side of the small finger has a projection called the olecranon process.

This has a sigmoid notch which articulates with the Humerus forming a hinge joint.

The olecranon offers a large surface for attachment of tendons, and overstretching of the forearm at the joint.