The Skeletal System 1 206 Bones in the Human Skeleton 2 Bones are Organs Each bone is a complex living organ made up of many cells, protein fibers, and minerals. They come in many sizes and shapes. The largest bone is the femur and the smallest is the stapes. The humerus is pictured here. 3 The femur is the thigh bone. The stapes is one of three small bones in the middle ear. The humerus is the upper arm bone. 3 The Skeletal System Also Includes Joints Cartilages Ligaments 4 Articular cartilage covers the ends of bones at articulations or joints Ligaments attach bones to other bones Tendons attach muscles to bones 4 5 Anatomy of the Skeletal System 5 Two Divisions of the Skeleton Axial Skeleton & Appendicular Skeleton 6