The humerus joins the radius and ulna (forearm) to form the elbow.
The forearm contains two long bones, the radius and the ulna, forming the radioulnar joint.
The radius and ulna (forearm bones) locked together so that there was no possibility of pronation or supination (twisting) as in human forearms.
Proximally, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus.
The best examples of ginglymus are the interphalangeal joints and the joint between the humerus and ulna.
At its lower end, the humerus has a larger facet contacting the radius than contacting the ulna.
The ulna is slender and cylinder-shaped with a length of 70% of that of the humerus.
It is the proximal extremity of the ulna which is articulated with the humerus and constituting a part of the elbow articulation.