8 The Skeletal and Muscular Systems

THE SKELETAL AND MUSCULAR SYSTEMS

DID YOU JUST MOVE? Hello! I'm a bone... And I'm a muscle! Did you know we just helped you open this book? Like all parts of your body, your bones and muscles are made up of tiny cells. These cells group together to make tissues. And these tissues form organs. BONE CELLS MUSCLE CELLS

Along with other organs and tissues, all of your bones and muscles form two very important organ systems. SKELETAL MUSCULAR The skeletal system forms a structure that supports and protects the body. The muscular system covers your bones and pulls them around. Without these systems, you wouldn't be able to sit, stand, walk, or even talk. Your body would be no more than a shapeless blob...

THE SKELETON Even though you rarely see them, your bones are the stars of your skeletal system. They are light, but also hard and strong. An adult human has about 206 bones! Your skeleton is also made up of a smooth, rubbery tissue called cartilage. Cartilage keeps bones from rubbing against one another. SKULL CLAVICLE RADILIS LILNA VERTEBRAL COLUMN STERNUM SCAPULA HUMERUS RIBS

Bones are joined to neighboring bones by... ...joints! Most joints are movable, like the joints in your arms and legs, or in your fingers. Ligaments, on the other hand- or foot, for that matter- hold your bones in place. Ligaments are bands of strong and stretchy tissue. Together, bones, ligaments, and cartilage make up your skeleton! PELVIC GIRDLE FEMUR PATELLA TIBIA FIBULA CARPALS METACARPALS PHALANGES

The skeleton protects some of the most important inner parts of the body— —like your brain! plop Your brain is surrounded by the bones of your skull. The bones of the skull are joined together to make a strong protective case around the brain. The joints of the skull bones don't move!