AA- Picking Up a Toddler

During this pandemic, we have been caring for my toddler niece, Evie. When I pick her up, I begin with my knees flexed, my hips flexed, and I extend my elbows to reach down to her. Once I have her in my arms, I extend my knees and hips and flex my elbows to bring her close to me. For my knees, from flexion to extension, the movements are being performed in the sagittal plane and act about the medial-lateral axis. The same is for my hips and elbows, in the sagittal plane and these actions act about the medial-lateral axis. I chose to focus on my elbows in this action. Through the course of this action, the osteokinematics dictate an open kinematic chain, because the joint is moving from extension to flexion. For arthrokinematics, the convex distal end of the humerus has the concave proximal ends of both the radius and ulna gliding along it anteriorly. The primary mover of elbow flexion, when picking up a toddler, is the biceps brachii, brachialis, and brachioradialis. It is a concentric contraction because the toddler (the load) is being brought up against gravity.