Elbow Bones, Ligaments, Muscles & Conditions

The elbow is composed of three separate joints, between three bones, and ligaments that provide stability. The three joints of the elbow complex work together, to allow bending (flexion) and straightening (extension). The joints also work together with the wrist joint to allow us to turn our hand palm up (supination) and palm down (pronation).

Bone and Joint

The three bones that make up the elbow joint are the humerus (upper arm,) and the two bones of the forearm, the radius and ulna. With your palm facing forward the radius is the bone that is most lateral and the ulna is the bone closest to your body.

The prominent part of the elbow on the posterior side (the pointed part) is called the olecranon, and is part of the ulna bone. On the inside and outside of the elbow lie the medial and lateral epicondyles. They are part of the distal humerus.

The three joints of the elbow are the ulnahumeral joint, the radiohumeral joint and the superior radioulnar joint. The superior radioulnar joint works with the inferior radioulnar joint of the wrist to turn our palm up and down. The osseous joint has articular cartilage, which covers the ends of the bones. The articular cartilage has a smooth and shiny surface that allows the ends of the bones to slide freely over each other.

Common elbow joint conditions include elbow fracture, olecranon fracture, radial head fracture, elbow dislocation, radial head dislocation, rheumatoid arthritis of the elbow and osteoarthritis of the elbow.

Muscles

The anterior muscles of the arm are the biceps, brachioradialis and brachialis. These muscles are strong flexors. The triceps muscle is the posterior muscle of the arm and extends or straightens the arm.

The medial epicondyle of the humerus serves as an attachment point for the tendons of the wrist flexors. The lateral epicondyle of the humerus serves as the attachment point for the tendons of the wrist extensors.

A tendon is the part of the muscle that attaches to a bone.  Common overuse injuries for these tendons are the medial epicondylitis (golfers elbow) and lateral epicondylitis (tennis elbow.) There are also deep muscles of the forearm that help to pronate (palm down) and supinate (palm up) the hand.

Common muscle conditions include biceps tendonitis, biceps tear, triceps tendonitis, lateral epicondylitis, medial epidcondylitis, golfers elbow and tennis elbow.

Ligaments

Ligaments are strong connective tissue structures that join bone to bone, providing stability to the elbow. There are four main ligaments in the elbow. The ulna collateral ligament, on the medial side of the elbow, connects the ulna to the humerus. The radial collateral ligament, on the lateral elbow, connects the radius to the humerus. The last two ligaments connect the radius to the ulna, and are the anular and quadrate ligaments.

Common elbow ligament conditions include elbow dislocation, anular ligament tear, radial head dislocation, UCL tear, ulna collateral ligament tear, ulna collateral ligament sprain and little league elbow.

Burse

A burse is a fluid filled sac that decreases friction between two tissues. In its normal state it has very little fluid. When it is irritated the burse fills with fluid and becomes painful. A burse can also protect boney structures or prominences. There are several bursae at the elbow. The olecranon burse is the most commonly irritated.

Common conditions affecting the burse include Elbow Bursitis and Olecranon Bursitis