Sarcolemma is the specialized form of cell membrane that lies on the outside of every muscle cell. Just beneath this cell membrane, the muscle fiber contains many threadlike myofibrils that lie alongside each other and play a fundamental role in the process of muscle contraction. This fiber responds to stimulation and when it responds, it contracts and relaxes. Each skeletal muscle fiber is a thin, longish cylinder with rounded ends that are attached to fascia relative to the muscle.