Skeletal muscle displays characteristic cross-striations under light microscopy resulting from the interdigitation of highly organized myosin and actin molecules. Individual myofilaments and fibrils inside muscle are associated with a complex tubular network called the sarcoplasmic reticulum . This structure plays an important role in controlling the contraction-relaxation state of muscle by regulating the concentration of calcium ions within muscle. Muscle fibers are arranged in bundles bound by dense connective tissue sheaths which helps to coordinate the force of contraction of individual fibers. A small population of satellite cells in adult skeletal muscle can divide and form new muscle after tissue damage.
Skeletal muscle is responsible for voluntary movements of limbs, digits, and other structures.
Skeletal muscle associated with the axial skeleton plays a role in maintaining posture. They exhibit a great deal of resistance to fatigue, and are suitable for maintaining sustained contraction. Red fibers predominate in the muscles of the limbs. They are also found in the intrinsic muscles of the back responsible for maintaining erect posture. While white fibers fatigue faster than red fibers, they are capable of generating large amounts of tension over a short period of time.