סקירה כללית של שרירי השלד

Skeletal muscles coordinate with other structures, such as nerves, bones, and blood vessels, to allow vertebrates to perform voluntary movements.

Skeletal muscles are a highly structured arrangement of cells and connective tissue layers. Tendons are collagenous fibers that connect the muscle to the bone.

A sheath of connective tissue called the epimysium encloses the skeletal muscle and separates and protects the muscle from friction against other structures during movement.

Within the epimysium are numerous fascicles, or cell bundles, surrounded by another connective tissue layer — the perimysium.

Each fascicle contains multiple muscle cells individually enclosed in a specialized plasma membrane called the sarcolemma. The sarcolemma surrounds the sarcoplasm, the cytoplasm of skeletal muscle cells.

A single muscle cell contains many myofibrils composed of actin and myosin. A myofibril has repeating units called sarcomeres formed by an alternating arrangement of thin actin and thick myosin filaments. A sarcomere forms the functional contractile unit of the skeletal muscle.