olecranon

The olecranon is the proximal, posterior projection of the ulna that forms the tip of the elbow. It is a large bony prominence at the upper end of the forearm bone, extending into the soft tissues and serving as a key lever for elbow movement. The olecranon, together with the coronoid process, forms the trochlear notch of the ulna, which articulates with the trochlea of the humerus. The articulation is mainly with the humerus at the trochlear notch when the elbow is extended, while the posterior surface of the olecranon serves as the attachment site for the triceps brachii tendon.

The triceps brachii tendon inserts on the superior posterior aspect of the olecranon, making it central to elbow extension. The bone is subcutaneous at the elbow, with a superficial olecranon bursa separating it from the skin; this bursa can become inflamed or swollen in olecranon bursitis, commonly known as “student’s elbow.”

Clinical significance arises from the olecranon’s role as a prominent extensor lever and its exposure to trauma. Falls on an outstretched hand can cause olecranon fractures, which may be displaced and require immobilization or surgical fixation. Avulsion injuries of the triceps at the olecranon can also occur. Osteoarthritic changes or inflammatory processes involving the elbow joint may involve the olecranon and its articular relationships.

In summary, the olecranon is the prominent, posterior part of the ulna essential for elbow extension, articulation with the humerus, and as the insertion point for the triceps tendon, with clinical relevance in fractures and bursitis.