Three fossa: Olecranon Fossa, Radial Fossa, & Coronoid Fossa
All three shallow depressions are located on the distal end of the humerus. The Olecranon fossa is on the posterior side and fits the olecranon process of the ulna. It is the deeper, larger depression. The radial fossa is located on the anterior side. It is a smaller depression located on the lateral side. The coronoid fossa is anterior and is medial to the radial fossa. It articulates with the coronoid process of the ulna.