Leg & surrounding bones:
The skeleton of the leg is composed of the femur (thigh bone), tibia
and fibula (calf bones), and the patella (kneecap). These bones have
three primary sites of articulation: the hip joint, formed by the head
of the femur and the acetabulum of the pelvis, the knee joint, formed by
the joining of the lower end of the femur, the patella, and the superior
end of the tibia and fibula, and the ankle, formed by the articulation
between the tibia and the tarsus. The legs are responsible for bearing
a great deal of weight and are subjected to intense vertical and lateral
stresses - especially at the knee joint. Consequently, the bones
of the leg are often cracked or broken, and the knee, hip, and ankle joint
are particularly susceptible to fracture, strain, sprain, and dislocation.
The femur is the longest bone in the body, and composes the upper leg, or thigh. Articulating with the acetabulum of the pelvis at its head, and the tibia, fibula, and patella to form the knee joint at its lower end, each femur directly bears the weight of the upper body.
The knee is the hinge-like joint formed by the lower end of the femur, the upper ends of the tibia and fibula, and the patella (kneecap). The patella is connected to the joint by the medial and patellar retinaculum ligaments and to the tuberosity of the tibia by the patellar ligament. It is not visible in the posterior (rear) view and is removed in the anterior (front) view to show the articulation and connective tissues of the bones beneath.
The knee is a joint which is subjected to tremendous lateral stress during normal activity and is guarded by a number of transverse and cruciate ligaments to help lend it support. Even so, however, the increased stresses placed upon this joint during extreme athletic activity (for example, in football, basketball, or tennis) which require the competitor to alter direction rapidly, the knee often bears the brunt of intolerable shearing force. Such incidences often result in torn ligaments within the knee which require corrective surgery.
The patella (kneecap) is a small bone of the knee joint which resembles an inverted teardrop. The patella is connected to the joint by the medial and patellar retinaculum ligaments and to the tuberosity of the tibia by the patellar ligament. It is not visible in the posterior (rear) view and is removed in the anterior (front) view to show the articulation and connective tissues of the bones beneath.
The tibia is the robust, primary bone of the two in the lower leg. Also called the shin-bone, the tibia bears most of the weight. Its head (upper, or proximal, end) articulates with the parallel fibula and the femur at the knee joint. At its distal, or lower, end it articulates with the fibula and the talus of the ankle. Protruding portions of the lower end of the tibia, called the medial malleolus (inside) and lateral malleolus (outside) form the large bumps which characterize the ankle joint.
The fibula is the smaller of the two bones of the lower leg. It articulates at each end with the parallel tibia, at its head (upper end) with the femur in the knee joint, and at its lower end with the bones of the ankle, or tarsus. The fibula is so named because it serves as a brace for the lower leg (fibula means "brace").
The head of the fibula is the somewhat broader upper, or proximal, end of the fibula. It articulates with the side of the tibia and is connected to the lateral condyle of the femur by the fibular collateral ligament.
The superior tibiofibular joint is the site of articulation between the head, or upper end, of the fibula and the head of the tibia.