In primates,[1] including humans, the elbow joint is the synovial hinge joint[2] between the humerus in the upper arm and the radius and ulna in the forearm which allows the hand to be moved towards and away from the body.[3] The superior radioulnar joint shares joint capsule with the elbow joint but plays no functional role at the elbow.[4] The elbow region includes prominent landmarks such as the olecranon (the bony prominence at the very tip of the elbow), the elbow pit, and the lateral and medial epicondyles. Terminology Ligaments Left elbow-joint Left: anterior and ulnar collateral ligaments Right: posterior and radial collateral ligaments The ligaments on either side of the elbow are triangular bands which blend with the joint capsule. They are positioned so that they always lie across the transverse joint axis and are, therefore, always relatively tense and impose strict limitations on abduction, adduction, and axial rotation at the elbow.[8] The ulnar collateral ligament has its apex on the medial epicondyle. Its anterior band stretches from the anterior side of the medial epicondyle to the medial edge of the coronoid proc

ss, while the posterior band stretches from posterior side of the medial epicondyle to the medial side of the olecranon. These two bands are separated by a thinner intermediate part and their distal attachments are united by a transverse band below which the synovial membrane protrudes during joint movements. The anterior band is closely associated with the tendon of the superficial flexor muscles of the forearm, even being the origin of flexor digitorum superficialis. The ulnar nerve crosses the intermediate part as it enters the forearm.[8] The radial collateral ligament is attached to the lateral epicondyle below the common extensor tendon. Less distinct than the ulnar collateral ligament, this ligament blends with the annular ligament of the radius and its margins are attached near the radial notch of the ulnaThe now obsolete length unit ell relates closely to the elbow. This becomes especially visible when considering the Germanic origins of both words, Elle (ell, defined as the length of a male forearm from elbow to fingertips) and Ellbogen (elbow). It is unknown when or why the second "l" was dropped from English usage of the word.