Which bone is primarily known for its role in the elbow joint?

The elbow joint is primarily formed by the interactions of three bones: the humerus, the radius, and the ulna. However, when focusing on the bone that plays a crucial role in the structure and function of the elbow joint, the ulna stands out as the most significant.

The ulna is one of the two long bones in the forearm, located on the inner side when in the anatomical position. It features a distinctive structure at its proximal end known as the olecranon process, which forms the bony prominence of the elbow. This structure fits into the olecranon fossa of the humerus when the arm is extended, allowing for a hinge-like movement at the elbow. This characteristic facilitates flexion and extension of the forearm relative to the upper arm.

While the humerus is also essential as it articulates with both the ulna and radius at the elbow, its role is more about providing the upper arm component rather than defining the elbow joint's articulation. The radius, on the other hand, allows for rotational movement of the forearm but does not provide the primary support for the elbow joint's hinge movement.

The scapula is not involved in the elbow joint at all, as it is part of the shoulder gird