The structure of the skeletal system consists of all the bones of the body and the cartilage, tendons and ligaments that join them together. It is involved in many vital functions of the body, including holding it up and protecting the organs. Without the skeleton, the body would just be a sack of organs held together by skin.
When referring to the structure of the skeletal system, it can be divided into the bones, or the actual skeleton; cartilage, a flexible and tough connective tissue around the joints which makes movement easier; and tendons and ligaments, which are soft tissues that connect bones to bones and bones to muscles. Together they allow movement of the joints and limbs.
The skeletal system can also be divided into the head, torso and limbs. The bones of the head include the skull and jaw and excludes the teeth, which are not considered bones due to their different make-up. The torso consists of the ribcage, shoulder blades and spine and ends at the pelvic bones and shoulders. The limb bones are the arm and leg bones, attached to the shoulders and pelvic bones and ending in the fingers and toes.
The number of bones in the human differs between babies and adults. At birth, humans have over 300 bones, many of which fuse together as the baby grows through childhood to adulthood and the structure of the skeletal system changes. The average adult has 206 bones making up their skeleton.
The bones which make up the structure of the skeletal system are constantly growing throughout life. Even in adulthood, the cells of the bones are constantly reabsorbed and regenerated. It is for this reason that, should a fracture or break of the bone occur, it is possible for them to heal completely. Bone health can be promoted by including calcium in the diet and doing weight-bearing exercise.
Not only does the skeletal system hold the body together, but it also protects parts of the body. The brain is protected by the skull, the heart and lungs are protected by the rib cage, and the nerves of the spinal cord are protected by the spine. Without the hard protection of the bones, these fragile organs would be far more likely to be damaged during any traumatic exposure.
The longest bone in the body is the femur, or thigh bone, and the smallest bone is the stirrup bone, located in the ear. The jawbone is the only bone in the head that can be moved, allowing speech and chewing.