How do muscles facilitate movement?

Muscles facilitate movement primarily through contraction and relaxation. When a muscle contracts, it shortens and pulls on the bones to which it is connected, producing movement. This contraction is initiated by signals from the nervous system. However, for continuous movement, the ability of muscles to relax is equally important; as one muscle contracts, its opposing muscle must relax to allow smooth and coordinated motion.

This interplay between contraction and relaxation enables a vast range of movements, from simple actions like flexing an arm to complex sequences such as walking or running. Muscles don't just change shape or use energy directly in isolation; rather, it is the alternating actions of contraction (to create motion) and relaxation (to restore the muscle to its original state) that are fundamental to how muscles operate within the musculoskeletal system.