Femur

The "femur" is the thigh bone, the longest bone in the body. The lower end joins the tibia (shin) to form the knee joint. The upper end is rounded into a ball (or "head" of the femur) that fits into a socket in the pelvis to form the hip joint. Just below the head is a constriction, or neck, and two large processes - an upper, lateral "greater trochanter" and a lower, medial "lesser trochanter." These processes provide attachments for muscles of the legs and buttocks. The neck of the femur gives the hip joint a wide range of movement, but it is a point of weakness and a common site of fracture.