1 — Head of radius; Articular circumference; 2 — Proximal radio-ulnar joint; 3 — Coronoid process; 4 — Olecranon; 5 — Trochlear notch; 6 — Radial notch; 7 — Articular fossa; 8 — Carpal articular surface; 9 — Radial styloid process; 10 — Dorsal tubercle; 11 — Articular circumference; 12 — Ulnar styloid process; 13 — Head of ulna; 14 — Distal radio-ulnar joint; 15 — Head of radius; 16 — Anular ligament of radius; 17 — Posterior surface; 18 — Ulna; 19 — Medial surface; 20 — Anterior surface