Biomechanics of Washing My Face

Every morning I wake up and I wash my face. I start with my shoulder and arm flexed and my digits/thumb are extended to wash, and end with my shoulders extended to rinse my hands. I first reach my arm over using my transverse plane about the longitudinal axis to turn the sink on. Then I use my sagittal plane about the frontal axis to flex my shoulders and arms to wash the soap on my face and to rinse my face. Lastly, I use the sagittal plane about the frontal axis to extend my shoulders and arms to rinse my hands under the sink. Regarding the osteokinematics of the shoulder, I am using flexion to extension of the shoulder in an open kinematic chain. Regarding arthrokinematics of the shoulder, the glenoid fossa of the scapula (concave surface) is stabilized and the humerus (the convex surface) is rolling posteriorly and gliding anteriorly. The primary mover, or agonist, in shoulder extension in this scenario is the anterior deltoid. This is working eccentrically because it is working negatively on the load and decelerating the arms as I rinse my hands under the water.