Activity Analysis: Putting earrings in my ears

 Each morning when I wake up, I put earrings in my ears. When I raise my hand to my ear, my elbow is starting in an extended position and is moving toward flexion. Flexion and extension at the elbow occurs in the sagittal plane. Since the motion is occurring in the sagittal plane, the motion occurs about a frontal axis. The osteokinematics of the elbow are extension to flexion in an open kinematic chain. When regarding the arthrokinematics, the moving ulna is the concave surface which rolls in an anterior direction on the convex surface. The concave surface is gliding in the same direction, anteriorly, on the stable convex surface of the humerous. The primary mover for elbow flexion is the biceps brachii muscle which is performing a concentric contraction.