The lower limb
The lower limb is divided into three sections. This consists of the thigh (hip to knee), the leg (knee to ankle) and the foot.
The thigh consists of a single long bone called the femur, which is the longest, heaviest and strongest bone in the body. It bears the weight of the body and shocks caused by movement.
The femur fits into a socket, known as the acetabelum in the pelvis, and at the other end joins the tibia to form the knee joint. The knee joint is a synovial hinge joint and only allows movements in a single plane (the sagittal plane). It allows flexion and extension only. However, when the knee is flexed, it also allows limited rotational movement.
The patella is a small triangular (sesamoid) bone in the tendon of the quadriceps femoris muscle, which lies on the front of the thigh. It helps to protect this joint.
The leg consists of two long bones (the tibia and fibula) which are arranged parallel to each other, but are unequal in size. The tibia is thick and heavy and is weight-bearing, whereas the fibula is slender and light and is non-weight-bearing. The fibula acts as a support to the ankle and to the muscles of the lower leg and lies laterally (to the outside) to the tibia.
The tibia and fibula are joined together with a tough, fibrous sheath, known as the interosseus membrane that allows limited rotational movement.