Final answer:
Hip flexion/extension involves the movement of the femur and tibia at the hip and knee joints. Hip flexion brings the knee closer to the chest, while hip extension pushes the knee away from the chest.
Step-by-step explanation:
The normal osteokinematics for hip flexion/extension involve the movement of the femur and tibia at the hip and knee joints.
During hip flexion, the angle between the thigh and trunk decreases as the femur moves forward, bringing the knee closer to the chest. This movement is initiated by the hip flexor muscles, such as the iliopsoas, rectus femoris, and sartorius.
On the other hand, during hip extension, the angle between the thigh and trunk increases as the femur moves backward, pushing the knee away from the chest. This movement is primarily achieved by the gluteus maximus muscle.