The olecranon fossa of the humerus accommodates the olecranon process of the ulna.

The bone that contains the olecranon fossa is the humerus, which is located in the upper arm. The olecranon fossa is a depression on the posterior side of the humerus that accommodates the olecranon process of the ulna when the arm is extended.

The landmark that contacts with olecranon fossa to form its joint is the olecranon process of the ulna. It forms the elbow joint with the humerus at the olecranon fossa, providing stability and allowing for extension of the forearm.

the olecranon fossa

olecranon fossa