<P> The elbow undergoes dynamic development of ossification centers through infancy and adolescence, with the order of both the appearance and fusion of the apophyseal growth centers being crucial in assessment of the pediatric elbow on radiograph, in order to distinguish a traumatic fracture or apophyseal separation from normal development . The order of appearance can be understood by the mnemonic CRITOE, referring to the capitellum, radial head, internal epicondyle, trochlea, olecranon, and external epicondyle at ages 1, 3, 5, 7, 9 and 11 years . These apophyseal centers then fuse during adolescence, with the internal epicondyle and olecranon fusing last . The ages of fusion are more variable than ossification, but normally occur at 13, 15, 17, 13, 16 and 13 years, respectively . In addition, the presence of a joint effusion can be inferenced by the presence of the fat pad sign, a structure that is normally physiologically present, but pathologic when elevated by fluid, and always pathologic when posterior . </P> <P> The function of the elbow joint is to extend and flex the arm grasp and reach for objects . The range of movement in the elbow is from 0 degrees of elbow extension to 150 of elbow flexion . Muscles contributing to function are all flexion (biceps brachii, brachialis, and brachioradialis) and extension muscles (triceps and anconeus). </P> <P> In humans, the main task of the elbow is to properly place the hand in space by shortening and lengthening the upper limb . While the superior radioulnar joint shares joint capsule with the elbow joint, it plays no functional role at the elbow . </P> <P> With the elbow extended, the long axis of the humerus and that of the ulna coincide . At the same time, the articular surfaces on both bones are located in front of those axes and deviate from them at an angle of 45 ° . Additionally, the forearm muscles that originate at the elbow are grouped at the sides of the joint in order not to interfere with its movement . The wide angle of flexion at the elbow made possible by this arrangement--almost 180 °--allows the bones to be brought almost in parallel to each other . </P>

What are the parts of the elbow called