The musculoskeletal system provides form, stability, and movement to the human body. It consists of the body's bones (which make up the skeleton), muscles, tendons, ligaments, joints, cartilage, and other connective tissue. The term "connective tissue" is used to describe the tissue that binds other tissues and organs together. Its chief components are elastic fibers and collagen, a protein substance. Connective tissue provides support to the various structures of the body—it holds organs in place and provides the underlying structure for all tissues
Bone is a constantly changing tissue that has several functions. Bones serve as rigid structures to the body and as shields to protect delicate internal organs. They provide housing for the bone marrow, where the blood cells are formed. Bones also maintain the body's reservoir of calcium. In children, some bones have areas called growth plates. Bones lengthen in these areas until the person reaches full height, at which time the growth plates close. Thereafter, bones grow very slowly—in thickness far more than in length.
Bones come together to form joints. The configuration of a joint determines the degree and direction of possible motion. Some joints do not move, except in very young children (during and for a short time after birth). Examples of such joints are those located between the plates of the skull. Other joints allow a large and complex range of motion. For example, the shoulder joints, which have a ball-and-socket design, allow inward and outward rotation as well as forward, backward, and sideways motion of the arms. Hinge joints in the elbows, fingers, and toes allow only bending (flexion) and straightening (extension).
Ligaments are tough fibrous cords, composed of connective tissue that contains both collagen and some elastic fibers. The elastic fibers allow the ligaments to stretch to some extent. Ligaments surround joints and bind them together; they help strengthen and stabilize joints, permitting movement only in certain directions. Ligaments also connect one bone to another.
Tendons are tough bands of connective tissue made up mostly of a tough protein called collagen. They do not stretch. Tendons firmly attach each end of a muscle to a bone.
Common Musculoskeletal Disorders
|
