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Elbow joints and ligaments
Other Terms: Elbow, Ligaments of the elbow joint
The elbow joint is a complex joint comprised of multiple articular surfaces within one articular capsule. The elbow joint can be subdivided into three distinct articular interfaces — the humero-ulnar joint, the humeroradial joint, and the proximal radioulnar joint. Two distinct pairs of movement occur as a result of the articulations within the elbow joint — the hinged movements of flexion and extension, which bend and straighten the elbow, and the rotational movements of pronation and supination, which roll the hand palm up and palm down. Unlike the shoulder joint, the elbow joint has strong extrinsic ligaments that limit movements and stabilize the articulating bones.
Humero-ulnar joint – hinge joint Humeroradial joint – combined hinge and pivot joint Proximal radio-ulnar joint – pivot joint
Humero-ulnar joint – trochlea of the humerus with the trochlear notch of the ulna Humeroradial joint –capitulum of the humerus with the head of the radius Proximal radio-ulnar joint – head of the radius with the radial notch of the ulna
Humero-ulnar and humeroradial joints - extension
The fibrous capsule is thin anteriorly and posteriorly allowing for free range of motion of flexion and extension in the hinge plane. On both lateral and medial sides strong extrinsic ligaments, the ulnar collateral and radial collateral ligaments, reinforce the capsule. These ligaments course from the epicondyles of the humerus to the respective sides of the ulna and radius where they stabilize the joint from side to side movements. Wrapping from the back of the ulna at the base of the olecranon to the front of the ulna at the lateral surface of the coronoid process is the semicircular annular ligament. With the radial notch of the ulna this ligament forms a fibro-osseous ring for the pivoting action of the radial head.