Introduction to the Musculo-Skeletal System

Movement in humans, as in other vertebrates, depends on two systems working together: the muscular system, which generates contractile force at the cellular level, and the skeletal system, which provides the rigid bones and the joints between them that this force is applied to as a set of levers. This unit looks at both halves of that partnership — first the fine structure and mechanism of skeletal muscle contraction (the motor unit, the contractile proteins actin and myosin, the sarcomere, and the sliding filament theory), and then selected, representative features of the human skeleton, including the skull, several named joints illustrating different joint types, and the bones of the limbs and their girdles.