Your elbow joint is where three bones in your arm meet: your upper arm bone (humerus) and the two bones in your forearm (radius and ulna). It is a combination hinge and pivot joint. The hinge part of the joint lets the arm bend and straighten; the pivot part lets the lower arm twist and rotate.
At the upper end of the ulna is the olecranon, the bony point of the elbow that can easily be felt beneath the skin.
On the inner and outer sides of the elbow, thicker ligaments (collateral ligaments) hold the elbow joint together and prevent dislocation. The ligament on the inside of the elbow is the ulnar collateral ligament (UCL). It runs from the inner side of the humerus to the inner side of the ulna, and must withstand extreme stresses as it stabilizes the elbow during overhand throwing.
Several muscles, nerves, and tendons (connective tissues between muscles and bones) cross at the elbow.The flexor/pronator muscles of the forearm and wrist begin at the elbow, and are also important stabilizers of the elbow during throwing.
The ulnar nerve crosses behind the elbow. It controls the muscles of the hand and provides sensation to the small and ring fingers.