Biomechanics- Reflection 1

Each day I put my car key in my ignition in order to drive to school. When I reach to insert my key into the ignition, my shoulder and elbow are flexed. After I turn the key my right hand is slightly supinated with my shoulder and elbow still in the flexed position. The motion of flexion at the shoulder and elbow occur in the sagittal plane about a frontal axis. The motion of supination of the hand occurs in the transverse plane about a vertical axis. The osteokinematics of the shoulder are flexion in an open kinematic chain. As for the arthrokinematics, the moving humerus is the convex segment, which rolls superiorly and glides inferiorly on the stationary concave segment, the glenoid fossa of the scapula. The deltoid is the prime mover for shoulder flexion, which performs a concentric contraction.