Which of the following describes the olecranon?

The olecranon is anatomically defined as a large bony projection of the ulna that forms the prominent point of the elbow joint. It serves as a key structural component, providing leverage for the muscles that extend the forearm. This projection not only plays a significant role in the movement and stability of the elbow joint but also serves as an attachment point for the triceps brachii muscle, which is responsible for elbow extension.

In contrast, the other options describe different anatomical structures or locations. A small bony structure in the wrist does not correlate with the olecranon, which is specifically associated with the elbow. The joint connecting the arm and shoulder refers to the glenohumeral joint, while a muscle in the forearm would pertain to various muscles that facilitate movement in that region, neither of which relate to the olecranon. Thus, the role of the olecranon as a bony projection of the ulna that forms the elbow joint is both anatomically and functionally distinct from the alternatives provided.