On what two structures does the radial head pivot during movements such as turning a doorknob

The two structures that the radial head pivot during turning are the capitulum and radial notch of humerus. The Capitulum is known as the elbow joint consist of the upper arm bone called the humerus and two forearm bones called the radius and the ulna. The Radial Notch of Humerus is a slender, oblong, articular depression on the adjacent side of the coronoid process.