Collateral ligaments of elbow joint

(A) The fan-like radial collateral is attached to the anular ligament of the radius, but its superficial fibers continue on to the ulna.
(B) The ulnar collateral ligament has a strong, round, cord-like anterior band (part), which is taut when the elbow joint is extended, and a weak, fan-like posterior band, which is taut when the joint is flexed. The oblique fibers merely deepen the socket for the trochlea of the humerus. The tubercle on the coronoid process is also known as the "sublime tubercle of the ulna."