Child Growth and Development researchers provide X-rays for the appearance and union sequences for the epiphyses of the hand and wrist.   In 1955, S. Idell Pyle and Norman L. Hoerr published X-rays that show the appearance and union sequences for the epiphyses of the knee.   However, no one has reported on the appearance and union sequences for the epiphyses of the elbow.

     By adolescence, diaphysial centers spread almost to the ends of the long bones.   The epiphysial centers appear in their cartilaginous locations and readily enlarge towards the diaphysial ossification center.   Consequently, X-rays show open areas only between diaphysial and epiphysial ossification centers.   These are metaphysial growth plates.   Long bone growth in length occurs on the diaphysial edge of these metaphysial growth plates.   When metaphysial growth plates ossify, long bone length growth stops.   However, bones are living tissue and, depending on the frequencies, directions and intensities of the mechanical stresses with which they must contend, continue to grow (hypertrophy) or shrink (atrophy).

     While evaluating epiphyses growth and development, remember that muscles attach to them.   The pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris and a slip of the flexor digitorum superficialis muscles attach to medial epicondyle epiphyses.   During forearm accelerations, these muscles exert tremendous stresses.   The extensor carpi radialis longus and extensor carpi radialis brevis muscles attach to lateral epicondyle epiphyses.   During decelerations, these muscles exert tremendous stresses.   The triceps brachii I and II muscles attach to the olecranon process epiphysis.   During forearm accelerations, these muscles exert tremendous stresses.

     Bi-lateral elbow X-rays taken on the tenth through sixteenth birthdates demonstrate elbow skeletal growth and development.   One subject’s elbow X-rays cannot represent all adolescent males.   Birthday elbow X-rays from large adolescent male samples would establish norms for elbow epiphyses appearance and union.

     Four adolescent pitching arm epiphyses are subject to irreparable injuries.   During forearm accelerations, the medial epicondyle's epiphysis receives considerable traction stresses from the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris and flexor digitorum superficialis muscles.   During recoveries, the capitulum's epiphysis receives a rebound collision stresses from the radial head's epiphysis.   During forearm accelerations, the olecranon process's epiphysis receives considerable traction stresses from the triceps brachii I and triceps brachii II muscles.