Yes, each muscle fiber, also known as a muscle cell, is surrounded by a modified cell membrane called the sarcolemma. The sarcolemma not only protects the inner components of the muscle fiber but also conducts electrical impulses along the muscle. These impulses lead to muscle contraction by interacting with the intracellular structure of the muscle fiber.

Underneath the sarcolemma is the sarcoplasm, which is similar to the cytoplasm in other cells but contains large amounts of glycogen (fuel for the cell) and myoglobin, an oxygen-binding protein.

The sarcolemma also invaginates into the interior of the muscle fiber, forming transverse (T) tubules that allow electrical impulses to penetrate deep into the cell, which is necessary for the coordinated contraction of the muscle fibers.

Importantly, each muscle fiber is filled with myofibrils, contractile units made up of sarcomeres, which are the smallest functional unit of the muscle and are responsible for muscle contraction. They are composed of actin and myosin protein filaments that slide against each other to contract the muscle when stimulated.