Biomechanics Post 1

Each day when I arrive at school I sit in my chair. When I start to lower my self into my chair,  I have to flex my knee. At the end of this movement, my knees are flexed and feet flat against the ground. Knee flexion decreases the angle between the lower leg and my femur. When flexing my knees to sit, the movement occurs occurs in the saggital plane about the frontal axis. Knee flexion occurs when my hamstrings are concentrically contracting to pull my tibia closer to the femur.The osteokinematics of sitting, is knee extension to knee flexion through a hinge joint. Sitting is a closed kinematic chain. This is because the feet are pressing against the floor to lower or raise my body. The distal part of my body is not moving free but is fixed to the floor.The arthokinematics of the tibiofemoral joint involve the convex distal femur which rolls posteriorly and glides anteriorly on the tibial plateau. The prime mover knee flexion is the hamstrings.Synergists muscles involved in knee flexion include the gastrocnemius, gracilis and sartorius.