Biomechanics Blog #1

Every morning I drink a cup of coffee. I start by grabbing a coffee mug from the top shelf of my cabinet. When I first reach for the cup, I flex my shoulder with a flexed arm at the elbow. Once I have reached the top shelf for a mug, my arm is extended at the elbow and my shoulder is flexed. My wrist is slightly flexed in order to grab the mug. My arm is extended at the elbow and my shoulder is flexed in the sagittal plane about a frontal axis. The osteokinematics of the arm at the elbow are flexion to extension in an open kinematic chain. In terms of artherokinematics, the ulnar concave surface rolls and glides in same direction on the convex surface of the humerus. The prime extensor of the elbow is the triceps brachii with help from the anconeus, which performs a concentric contraction.