The femur, or thigh bone, consists of a head, neck, body, trochanters, condyles and intercondylar fossa, notes InnerBody. The femur is the longest and heaviest bone in the body, capable of supporting nearly all of the body's weight.
The head of the femur forms the ball of the ball-and-socket joint at the hip and allows the femur to move freely in nearly all directions, says InnerBody. The neck of the femur is thin and is the bone's weakest point; it is the most likely spot for fractures. It extends away from the femur to provide a range of leg movements. The greater and lesser trochanters sit at the top of the femur's body. These projections serve both to widen and support the bone in a high-stress area and to provide connection point for several important groin and hip muscles.
The opposite end of the femur joins with the tibia to form the knee joint, states InnerBody. This end of the femur is very wide and comprises the medial and lateral condyles. The condyles articulate with medial and lateral condyles on the tibia. The intercondylar fossa, a depression between the condyles, provides space for the ligaments that support the knee joint.