The elbow joint is classified as a synovial hinge joint that is formed by three bones: The humerous bone (bone of the upper arm), the radius (the bone on the thumb side of the forearm) and the ulna (the longer of the two forearm bones, located medially from the radius).
The elbow joint is essentially made up of three smaller joints. The humeroulnar joint (formed by the humerous and ulna bones) functions like a door hinge, with the olecranon (pointy part of elbow) acting as the stopper. The humeroradial joint (formed by the humerous and radius) functions more like a ball and socket. There is also a pivot joint between the radius and ulna, called the proximal radioulnar joint (there is also a distal radioulnar joint in the wrist). This joint allows the radius bone to rotate over the ulnar bone when you change palm position.
The elbow joint is stabilized by the radial and ulnar collateral ligaments as well as the anular ligament. There is articular cartilage within the elbow joint to protect the bones from one another during movement. This joint is also an anchor point for both the triceps brachii and biceps brachii tendons which cause extension and flexion respectively. Blood to the elbow joint is supplied by branches of the brachial, radial and ulnar arteries.
Although the elbow joint is strong due to its structure and one-axis range of motion, it is susceptible to fractures and dislocations caused by blunt force.