Biceps

The triarticulate biceps brachii muscles, particularly the short head enters passive insufficiency through the completion of elbow extension when the shoulders are more extended or through the completion of shoulder extension when the elbows are more extended. The triarticulate biceps brachii muscles, particularly the short head enters active insufficiency through the completion of elbow flexion when the shoulders are more flexed (brachialis becomes more active) or through the completion of shoulder flexion when the elbows are more flexed.