What bones are involved in knee flexion?

Knee flexion involves the articulation of two bones:

1. Femur: The femur, or thigh bone, is the long bone of the upper leg. It forms the superior portion of the knee joint.

2. Tibia: The tibia, or shin bone, is the larger and stronger bone of the two bones in the lower leg. It articulates with the femur and forms the inferior portion of the knee joint.

When knee flexion occurs, the tibia moves posteriorly relative to the femur. The movement is made possible by the contraction of various muscles, including the hamstring muscles on the posterior side of the thigh, and is controlled by ligaments and other surrounding soft tissue structures.