Taking a Drink of Water

An action that I participate in every day that is part of my daily routine is taking a drink of water. I do this to try and stay hydrated throughout the day. When I hold my water bottle and bring it towards my mouth, my fingers are flexed to grip the water bottle, my shoulder flexes to bring the water bottle to my mouth and my elbow flexes to bring the bottle closer to my face. Flexing my fingers, elbow and shoulder all occur in the sagittal plane about a frontal axis. 

            The osteokinematics of these motions are open-chain. During shoulder flexion, the convex humeral head spins and rolls inferiorly and anteriorly glides within the concave glenoid fossa of the scapula. During elbow flexion, the convex end of the humerus articulates with the concave proximal end of the ulna. The proximal end of the ulna glides anteriorly with the humerus. Additionally, the radial head glides anteriorly with the humerus. 

            The prime mover of shoulder flexion is the anterior deltoid. This is a concentric contraction because it is causing the muscle to shorten.