Biomechanics Blog 1 - Activity Analysis

Most days I put my hair up in a bun. When I raise my arms, my shoulder and elbow are both in a flexed position (start: arms down, end: arms up) and my shoulders also abduct. My wrists perform both radial and ulnar deviation when smoothing my hair and forming the bun. My phalanges flex to hold my hair in place and put the hair band in. The flexion on my elbow and shoulder is happening in the sagittal plane about a coronal axis, and the abduction of my shoulder is in the frontal plane about a sagittal axis. The osteokinematics of the shoulder is extension to flexion in an open kinematic chain. For the arthrokinematics, the moving humerus is the convex segment that rolls posteriorly and glides anteriorly in the stable concave glenoid fossa. The prime mover for shoulder flexion will be the deltoid, which performs a concentric muscle activation.