What is the function of the sarcoplasmic reticulum in muscle fibers?

.Skeletal muscles are known as voluntary muscles because their activities are under the voluntary control of the nervous system. Each organised skeletal muscle in the body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fasciA.Each muscle fiber is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm.The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibers is the storehouse of calcium ions.