The radius is the larger bone which articulates with the ulna on the lower half of the arm (on the thoracic limb just distal to the patella, proximal to the carpal). Pay attention to the radial tuberosity and the capitular fossa labeled here.

The ulna lies parallel to the radius and contains the olecranon tuber and olecranon process, the anconeal process, and the trochlear notch on its proximal end. It also has the styloid process on the distal portion of the bone.